GOLF CLUB HEADS WITH INTERNAL UNDERCUTS

Described herein is a hollow body iron-type golf club head having a sole and ballast configured to relieve stress within a forward region of the sole. In a first configuration, the golf club head comprises a ballast undercut for relieving stress. In other configurations, the ballast undercut is combined with additional stress relief features, such as a cascading sole near the face sole juncture, for further reductions to face thickness. In further configurations, the ballast defines a recess for receiving a ballast weight having a density greater than the body, thereby improving mass properties of the golf club head.

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Description
RELATED APPLICATIONS

This is a continuation in part of U.S. patent application Ser. No. 17/656,371, filed on Mar. 24, 2022, which claims the benefit to U.S. Provisional Patent Application No. 63/200,726, filed on Mar. 24, 2021, and is a continuation in part of U.S. patent application Ser. No. 17/237,010, filed on Apr. 21, 2021, now U.S. Pat. No. 11,458,373, issued on Oct. 4, 2022, which claims the benefit to U.S. Provisional Patent Application No. 63/013,341, filed on Apr. 21, 2020. This also claims the benefit to U.S. Provisional Application No. 63/601,652, filed on Nov. 21, 2023, U.S. Provisional Application No. 63/619,672, filed on Jan. 10, 2024, U.S. Provisional Application No. 63/555,353, filed on Feb. 19, 2024, and U.S. Provisional Application No. 63/663,644, filed on Jun. 24, 2024, all of which are incorporated herein by reference.

FIELD

The present disclosure relates generally to golf equipment, and more particularly, to flexure structures for improved performance characteristics of hollow body irons and methods to manufacture hollow body irons with flexure structures.

BACKGROUND

Hollow body irons, ideally, operate as a diving board, initially deflecting rearward during impact and subsequently returning forward. In club design, the degree to which a hollow body iron behaves as a diving board, or spring is constrained by peak stress values. To ensure that traditional golf clubs do not exceed maximum stress limits, the face and sole are thickened such that the club is made more rigid. The rigidity of the traditional golf clubs results in a degradation to the diving board, or spring behavior of the club head. Therefore, there is a need in the art to produce a golf club head having a construction which expands the limit of modifications to the face to improve energy transfer from the club to the ball at impact.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a toe end perspective view of a hollow body club head according to one embodiment.

FIG. 2A depicts a toe side cross-sectional view of the hollow body club head of FIG. 1.

FIG. 2B depicts an enlarged view of a portion of the hollow body club head of FIG. 2A.

FIG. 3 depicts a front view of an internal cavity of FIG. 1.

FIG. 4A depicts a cross-sectional view of a hollow body club, similar to the hollow body club of FIG. 1, according to another embodiment comprising a ballast with an angled forward surface.

FIG. 4B depicts an enlarged view of the ballast and undercut of the hollow body club of FIG. 4A.

FIG. 5 depicts a toe end perspective view of the hollow body club of FIG. 4A with the strikeface removed, showing the internal cavity.

FIG. 6A depicts a cross-sectional view of a hollow body club, similar to the hollow body club of FIG. 1, according to another embodiment.

FIG. 6B depicts an enlarged view of a portion of the hollow body club of FIG. 6A.

FIG. 7 depicts a top cross-sectional view of the hollow body club of FIG. 6A, highlighting the cascading region within the internal cavity.

FIG. 8 depicts a cross-sectional view of a prior art hollow body club, according to another embodiment.

FIG. 9 is a graphical representation of ball velocity, measured in mph, of both a control club head a club according to the present invention.

FIG. 10 is a graphical representation of vertical launch angle, in degrees, of both a control club head a club according to the present invention.

FIG. 11 is a graphical representation of spin rate, in rpm, of both a control club head a club according to the present invention.

FIG. 12 is a graphical representation of vertical launch angle, in degrees, of both a control club head a club according to the present invention.

FIG. 13 is a graphical representation of spin rate, in both wet and dry conditions, of both a control club head a club according to the present invention.

FIG. 14 is a graphical representation of ball speed in both wet and dry conditions, measured in mph, of both a control club head a club according to the present invention.

FIG. 15 depicts a cross-sectional view of a golf club head according to an embodiment.

FIG. 16 depicts a rear view of the golf club head of FIG. 15 without an insert.

FIG. 17 depicts a rear view of the golf club head of FIG. 15 with an insert.

FIG. 18 depicts a front cross-sectional view of the golf club head of FIG. 15.

FIG. 19 depicts a cross-sectional view of the golf club head of FIG. 15.

FIG. 20 illustrates a rear view of a golf club head according to an embodiment.

FIG. 21 illustrates a front cross-sectional view of the golf club head of FIG. 20.

FIG. 22 illustrates a rear view of a golf club head according to an embodiment.

FIG. 23 illustrates a rear view of the golf club head of FIG. 22 without an insert.

FIG. 24 illustrates an internal view of the golf club head of FIG. 22 without a strike face insert.

FIG. 25 illustrates a front cross-sectional view of the club head of FIG. 22.

FIG. 26 illustrates a cross-sectional view of the golf club head of FIG. 22, taken nearer a heel.

FIG. 27 illustrates a cross-sectional view of the golf club head of FIG. 22, taken nearer a center.

FIG. 28 illustrates a cross-sectional view of the golf club head of FIG. 22, taken nearer a toe.

FIG. 29 illustrates a rear view of a golf club head according to an embodiment.

FIG. 30 illustrates an internal view of the golf club head of FIG. 29 without a strike face insert.

FIG. 31 illustrates a front cross-sectional view of the golf club head of FIG. 29 without a ballast weight.

FIG. 32 illustrates a cross-sectional view of the golf club head of FIG. 29.

FIG. 33 illustrates a detailed cross-sectional view of the golf club head of FIG. 29.

FIG. 34A illustrates a rear cross-sectional view of a golf club head according to an embodiment.

FIG. 34B illustrates a rear cross-sectional view of a golf club head according to an embodiment.

FIG. 34C illustrates a front cross-sectional view of a golf club head according to an embodiment.

FIG. 34D illustrates a front cross-sectional view of a golf club head according to an embodiment.

FIG. 34E illustrates a front cross-sectional view of a golf club head according to an embodiment.

FIG. 34F illustrates a front cross-sectional view of a golf club head according to an embodiment.

FIG. 35 illustrates a cross-sectional view of a golf club head according to an embodiment.

FIG. 36 illustrates a front view of the insert of the golf club head of FIG. 35.

FIG. 37 illustrates a rear view of the golf club head of FIG. 35.

FIG. 38 illustrates a rear view of the golf club head of FIG. 35 without an insert.

FIG. 39 illustrates a cross-sectional view of a golf club head according to an embodiment.

FIG. 40 illustrates a detailed front cross-sectional view of the golf club head of FIG. 39 without an insert.

FIG. 41 illustrates a rear view of the golf club head of FIG. 39.

FIG. 42 illustrates a cross-sectional view of a golf club head according to an embodiment.

FIG. 43 illustrates a front cross-sectional view of the golf club head of FIG. 42.

FIG. 44 illustrates a perspective view of the insert of the golf club head of FIG. 42.

FIG. 45 illustrates a cross-sectional view of a golf club head according to an embodiment.

FIG. 46 illustrates a front view of a golf club head according to an embodiment without a strike face insert.

FIG. 47 illustrates cross-sectional view of the golf club head of FIG. 46.

FIG. 48 illustrates a perspective view of the damping member of the golf club head of FIG. 46.

FIG. 49 illustrates a stat area plot comparing an exemplary club head according to aspects of the present invention to a control club head.

For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.

The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “include,” and “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus.

The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

The terms “couple,” “coupled,” “couples,” “coupling,” and the like should be broadly understood and refer to connecting two or more elements or signals, electrically, mechanically and/or otherwise.

The term “ground plane,” as used herein, can refer to a reference plane associated with the surface on which a golf ball is placed. The ground plane can be a horizontal plane tangent to the sole at an address position.

The terms “loft” or “loft angle” of a hollow body golf club (hererafter “hollow body” or “hollow body iron” or “iron-type golf club head” or “golf club head”), as described herein, refers to the angle formed between the club face and the shaft, as measured by any suitable loft and lie machine. A loft plane lies tangent to the strikeface at the geometric center. A loft angle is measured between the ground plane and the loft plane. In many embodiments, the loft angle of the club head is less than approximately 50 degrees, less than approximately 49 degrees, less than approximately 48 degrees, less than approximately 47 degrees, less than approximately 46 degrees, less than approximately 45 degrees, less than approximately 44 degrees, less than approximately 43 degrees, less than approximately 42 degrees, less than approximately 41 degrees, less than approximately 40 degrees, less than approximately 39 degrees, less than approximately 38 degrees, less than approximately 37 degrees, less than approximately 36 degrees, less than approximately 35 degrees, less than approximately 34 degrees, less than approximately 33 degrees, less than approximately 32 degrees, less than approximately 31 degrees, less than approximately 30 degrees, less than approximately 29 degrees, less than approximately 28 degrees, less than approximately 27 degrees, less than approximately 26 degrees, less than approximately 25 degrees, less than approximately 24 degrees, less than approximately 23 degrees, less than approximately 22 degrees, less than approximately 21 degrees, less than approximately 20 degrees, less than approximately 19 degrees, less than approximately 18 degrees, 17, or less than approximately 16 degrees. Further, in many embodiments, the loft angle of the club head is greater than approximately 16 degrees, greater than approximately 17 degrees, greater than approximately 18 degrees, greater than approximately 19 degrees, greater than approximately 20 degrees, greater than approximately 21 degrees, greater than approximately 22 degrees, greater than approximately 23 degrees, greater than approximately 24 degrees, greater than approximately 25 degrees, greater than approximately 26 degrees greater than approximately 27 degrees, greater than approximately 28 degrees, greater than approximately 29 degrees, greater than approximately 30 degrees, greater than approximately 31 degrees, greater than approximately 32 degrees, greater than approximately 33 degrees, greater than approximately 34 degrees, greater than approximately 35 degrees, greater than approximately 36 degrees, greater than approximately 37 degrees, or greater than approximately 38 degrees.

DESCRIPTION

The present disclosure describes technologies for an improved hollow body iron-type golf club head (hererafter “hollow body” or “hollow body iron” or “iron-type golf club head” or “golf club head” or “cap back iron” or “cap back golf club head”) having a sole and ballast configured to relieve stress within a forward region of the sole. In some embodiments, the golf club head comprises a ballast undercut for relieving stress. The ballast undercut may be combined with additional stress relief features, such as a cascading sole near the face sole juncture, for further reductions to face thickness. Still further, the ballast may be a weighted ballast, which improves physical characteristics of the club, such as CG and MOI, in addition to reliving stress and permitting reduced face thickness.

The hollow body can comprise a strikeface, a rearward region, opposite the strikeface, a heel portion, a toe portion, opposite the heel, a sole, and a top rail to define an interior cavity. The rearward region can further include a ballast extending forward from the rearward region and into the interior cavity. In many embodiments, the ballast is an internal component such that it is not visible from the exterior of the golf club. The ballast can further comprise a geometry configured to increase the interior surface area of the sole. For example, in some embodiments, the ballast can comprise a top surface, a forward surface, and a bottom surface defined as an undercut region. In such embodiments, when viewed from a toe side cross section, an undercut is formed by a concave geometry, relative to the face, in the bottom surface. In other embodiments, a forward surface of the ballast may be angled towards the face such that the ballast includes an overhang suspended over the sole. In such embodiments, an undercut is formed between the ballast forward surface and the interior surface of the sole. The undercut allows the thinner, forward region of the sole to extend beneath the ballast. A ballast comprising a bottom undercut surface and/or an angled forward surface, as opposed to a forward surface that meets the interior surface of the sole at a right angle, prevents stress from concentrating along the sole between the face and the ballast and increases the portion of the sole capable of storing strain energy. Hollow body irons comprising an undercut, therefore, allows thicknesses of the sole and face to be reduced more than hollow body irons without an undercut.

The sole of the hollow body iron can be divided into two regions, the forward region and the rearward region. The forward region is adjacent the strikeface and has less thickness relative to the reward region, which can store strain energy. The rearward region is adjacent to the to the rearward region of the of the body and has greater thickness relative to the forward region, and therefore does not store strain energy. In other words, the forward region of the sole 132 is the portion of the sole 110 that behaves as a spring. Hollow body irons having a thinner face and extended forward sole region, as a result of the ballast undercut, store more strain energy (i.e., potential energy) than the face and forward sole region of a club without an undercut. Consequently, the undercut improves the spring-like energy transfer between the club body and the golf ball (as compared to a golf club without an undercut). This energy transfer further can be improved in hollow body irons when the forward sole region also comprises a cascade, in addition to the undercut. The cascading sole improves the flow of stress within the forward region of the sole near the face sole juncture, while the undercut improves the flow of stress near the ballast. Accordingly, the undercut and/or the combination of the undercut and cascading sole allows face thickness to be reduced by 3-8%. Thus, the thinner face, which had been previously unattainable, results in an improved flight trajectory and distance.

The hollow body iron can further comprise a weighted ballast utilizing high density materials to improve physical characteristics of the club head such as lower CG and increase MOI. The weighted ballast comprises at least one ballast weight that is seated within at least one recess within the weighted ballast. The at least one ballast weight can be sized and positioned within the weighted ballast as desired to achieve a desired CG and/or MOI. The at least one ballast weight is exposed to the interior cavity and forms at least a portion of the interior surface of the cavity. The at least one ballast weight has surfaces that adjoin the surrounding surfaces of the weighted ballast and interior cavity. The recess and ballast weight have complementary geometry to sufficiently secure and form a solid weighted ballast.

A. Undercut

i. Undercut Formed by Bottom Surface of Ballast

An iron-type golf club head 100 exterior having an internal stress relieving sole 110 and ballast 114 having an undercut 102 is illustrated at FIGS. 1-3. The golf club head 100 comprises a hollow body structure with an internal cavity 104. The hollow body structure of golf club head 100 is further defined by a strikeface 106, a rearward region 108 opposite the strikeface 106, a heel portion 103, a toe portion 105 opposite the heel portion 103, a sole 110, and a top rail 112 opposite the sole 110.

FIG. 2A illustrates a heel cut away view of the FIG. 1 golf club head 100. FIG. 2A shows the internal cavity 104 and stress relieving features of golf club head 100. The rearward region 108 further comprises a ballast 114 located within the internal cavity 104. As shown in FIG. 2A, the ballast 114 is an integral weighting element necessary for optimal CG (center of gravity) positioning in golf club head 100. The ballast 114 is a solid structure protruding vertically from the sole 110, forward from the rearward region 108, and extending along the sole 110 in a heel to toe direction. A forward region 132 of the sole 110 is defined between the strikeface 106 and the ballast 114.

Continuing to refer to FIG. 2B, the ballast 114 comprises a top surface 116, a forward surface 118, and a bottom surface 120. As illustrated, the bottom surface 120 is contoured to create a relief defining an undercut region 128 with undercut 102. The undercut region 128 of the ballast 114 is a concave void located adjacent an interior surface 122 of the sole 110. The undercut region 128 comprises undercut 102 and an undercut transition 141. The undercut region 128 extends laterally in a heel to toe direction over a heel to toe length 124 of the ballast 114. In the illustrated embodiment, the undercut 102 is generally centered within the golf club head 100 between the heel portion 103 and toe portion of the golf club head 100. As shown in FIG. 2B, the undercut 102 extends beneath the ballast 114, such that forward region 132 of the sole 110 is bounded between the face and the undercut 102/bottom surface 120 of the ballast 114. The forward region 132 of the sole 110 is effectively lengthened, as compared to golf club head without an undercut (i.e., a forward region defined between the strikeface and the forward surface of the ballast). Therefore, the undercut 102 not only reduces stress in the forward region 132 of the sole, but creates a larger spring (i.e., the forward region of the sole) for transferring energy back to the ball at impact.

FIG. 2B depicts an enlarged view of the ballast 114 and undercut 102. As shown in FIG. 2B, the ballast 114 comprises top surface 116, forward surface 118, and bottom surface 120. The ballast 114 protrudes vertically from an interior surface of the sole 110 along an interior surface of the rearward region 108. The bottom surface 120 comprises a contoured geometry that extends inward, from the forward surface 118 toward the rearward region 108 to define the undercut 102, which extends in a heel to toe direction. Continuing to refer to the FIG. 2B cross section, the ballast bottom surface 120 further comprises an undercut juncture 130 defined as the juncture between the ballast bottom surface 120 and the interior surface 122 of the sole 110. The undercut juncture 130 is a rearmost point of the ballast bottom surface 120 that defines the undercut 102. As shown, the forward region 132 of the sole is defined between the strikeface 106 and the undercut juncture 130, rather than the strikeface 106 and the forward surface 118 in a hollow body iron without undercut 102.

The undercut 102 can be described with reference to four parameters, namely an undercut depth 134, an undercut height 136, an undercut length 138, and an undercut sole thickness 123, as best shown in FIG. 2B. Further, the ballast bottom surface 120 can be curved such that the undercut 102 is defined between an undercut bottom edge 139 and an undercut top edge 137. The undercut depth is measured as a perpendicular distance between a ballast forward plane 20 and the undercut juncture 130 (i.e., the rear most point of the undercut). The undercut height 136 is defined as the vertical distance between an undercut top edge 137 and an undercut bottom edge 139. The undercut length is measured parallel to a ground plane between the undercut toe end 133 and the undercut heel end 135. Finally, the undercut sole thickness 123 is measured as the perpendicular distance from the exterior surface of the sole 121 and an interior surface of the sole 121. In a first embodiment, the undercut 102 has a depth 134 of 0.065 inch, a height 136 of 0.083 inch, a length of 1.16 inches.

The undercut depth 134, between the ballast forward plane 20 and the undercut juncture 130, has a range of 0.010 inch to 0.100 inch. For example, the undercut depth 134 can be 0.010 inch, 0.015 inch, 0.020 inch, 0.025 inch, 0.030 inch, 0.035 inch, 0.040 inch, 0.045 inch, 0.050 inch, 0.055 inch, 0.060 inch, 0.065 inch, 0.070 inch, 0.075 inch, 0.080 inch, 0.085 inch, 0.090 inch, 0.095 inch, or 0.100 inch. Alternatively, an undercut face depth 131 can be measured as the perpendicular distance between an interior surface of the strikeface 106 and the undercut juncture 130. In some embodiments, the undercut depth from the face ranges from 0.200 inch to 0.500 inch. For example, the undercut depth from the face can be 0.200 inch, 0.220 inch, 0.240 inch, 0.260 inch, 0.280 inch, 0.300 inch, 0.320 inch, 0.340 inch, 0.360 inch, 0.380 inch, 0.400 inch, 0.420 inch, 0.440 inch, 0.460 inch, 0.480 inch, or 0.500 inch.

The undercut height 136, measured between the undercut bottom edge 139 and undercut top edge 137, can range from 0.030 inch to 0.200 inch. For example, the undercut height 136 range from 0.030 inch to 0.040 inch, 0.040 inch to 0.050 inch, 0.050 inch to 0.060 inch, 0.060 inch to 0.070 inch, 0.070 inch to 0.080 inch, 0.080 inch to 0.090 inch, 0.090 inch to 0.100 inch, 0.100 inch to 0.110 inch, 0.110 to 0.120 inch, 0.120 inch to 0.130 inch, 0.130 inch to 0.140 inch, 0.140 inch to 0.150 inch, 0.150 inch to 0.160 inch, 0.160 inch to 0.170 inch, 0.170 inch to 0.180 inch, 0.180 inch to 0.190 inch, or 0.190 inch to 0.200 inch.

FIG. 3 depicts a front view of golf club head 100 wherein the strikeface 106 is removed to expose the undercut length 138 extending from the undercut heel end 135 to the undercut toe end 132. In some embodiments, the undercut length 138 ranges from 0.5 inch to 3.0 inches. In other embodiments, the undercut length ranges from 0.50 inch to 0.75 inch, 0.75 inch to 1.00 inch, 1.00 inch to 1.25 inches, 1.25 inches to 1.50 inches, 1.50 inches to 1.75 inches, 1.75 inches to 2.00 inches, 2.00 inches to 2.25 inches, 2.25 inches to 2.50 inches, 2.50 inches to 2.75 inches, or 2.75 inches to 3.00 inches. FIG. 3 further shows the ballast length 124, which can be measured from a ballast heel end 125 to a ballast toe end 127. In some embodiments the ballast length 124 ranges from 1.0 inch to 3.0 inches. In other embodiments the ballast length 124 is 1.2 inches, 1.4 inches, 1.6 inches, 1.8 inches, 2.0 inches, 2.2 inches, 2.4 inches, 2.6 inches, 2.8 inches, or 3.0 inches.

The undercut length 138, measured as the distance between the undercut heel and toe ends, may further define a percent of the ballast length 124, to describe the portion of the ballast 114 comprising the undercut 102. In embodiments of iron type golf club heads comprising an undercut 102, the undercut 102 can increase the surface area experiencing impact loading. The percent ballast length can be calculated as the undercut length 138 divided by the ballast length 124. In some embodiments, the undercut percent ballast length ranges from 20% to 100%. The length of the undercut can range from 10% the length of the ballast length up to the same length as the ballast length (i.e., 100%). For example, the percent ballast length is 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

In addition, an undercut transition height 142, as shown in FIG. 2B, is defined as the perpendicular distance between an interior surface 122 of the sole 110 and forward surface lower edge 140. In some embodiments, the transition height 142 can range from 0.150 inch to 0.300 inch. The transition height can range from 0.150 inch to 0.160 inch, 0.160 inch to 0.170 inch, 0.170 inch to 0.180 inch, 0.180 inch to 0.190 inch, or 0.190 inch to 0.200 inch, 0.200 inch to 0.210 inch, 0.210 to 0.220 inch, 0.220 inch to 0.230 inch, 0.230 inch to 0.240 inch, 0.240 inch to 0.250 inch, 0.250 inch to 0.260 inch, 0.260 inch to 0.270 inch, 0.270 inch to 0.280 inch, 0.280 inch to 0.290 inch, or 0.290 inch to 0.300 inch In the first embodiment discussed above, the transition height is 0.185 inch. The undercut transition 141 having transition height 142 and a contoured profile allows the undercut 102 to smoothly transition to the ballast forward surface 118. This smooth transition promotes an even flow of stress through the undercut 102 and the ballast 114.

As discussed above, the undercut 102 and undercut region 128 can be considered as a region of ballast material that has been removed, when compared to iron-type golf club heads lacking an undercut. An undercut volume is defined by a surface 146 of the undercut region 128 and the ballast forward plane 20. For example, in one embodiment, the surface 146 of the undercut region and the ballast forward plane 20 define an undercut volume of 0.018 cubic inches. In other embodiments, the undercut volume ranges from 0.018 cubic inches to 0.050 cubic inches. For example, the undercut volume can be 0.018 cubic inches, 0.020 cubic inches, 0.022 cubic inches, 0.024 cubic inches, 0.026 cubic inches, 0.028 cubic inches, 0.030 cubic inches, 0.032 cubic inches, 0.034 cubic inches, 0.036 cubic inches, 0.038 cubic inches, 0.040 cubic inches, 0.042 cubic inches, 0.044 cubic inches, 0.046 cubic inches, 0.048 cubic inches, or 0.050 cubic inches. The undercut volume can be used to calculate mass removed from the ballast 114 by the undercut region 128. Mass is calculated by multiplying the undercut volume by the material density of the ballast 114. For example, an undercut volume ranging from 0.018 cubic inches to 0.030 cubic inches. The undercut volume can be 0.018 cubic inches, 0.020 cubic inches, 0.022 cubic inches, 0.024 cubic inches, 0.026 cubic inches, 0.028 cubic inches, or 0.030 cubic inches. The amount of material removed from the ballast to form the undercut with a material density ranging from 6.0 g/cm3 to 7.75 g/cm3 or a range of mass from 1.75 grams to 2.40 grams. The amount of material removed from the ballast to form the undercut with a material density of 6.0 g/cm3, 6.5 g/cm3, 7.0 g/cm3, or 7.75 g/cm3 or a mass of 1.75 grams, 2.0 grams, 2.20 grams, 2.32 grams or 2.40 grams from the ballast 114.

The forward region 132 of the sole 110 extending from the strikeface 106 to the ballast 114 affects the impact response of golf club head 100 with a golf ball. As shown in FIG. 2B, the undercut juncture 130 is spaced further rearward from the strikeface 106 than the ballast forward surface 118. The undercut juncture's additional distance from the strikeface 106, means that the thinner, forward region 132 of the sole 110 has been effectively lengthened (relative to an overall front-to-rear sole width) such that part of the forward sole region extends beneath the ballast 114 (as compared to traditional golf club heads, which lack the undercut 102). A forward sole length can be measured as the perpendicular distance between the undercut juncture 130 and the strikeface 106. In some embodiments, the effective increase in length ranges from 6% to 12%. For example, the undercut 102 can increase length of the forward sole region 132 by 6% to 7%, 7% to 8%, 8% to 9%, 9% to 10%, and 11% to 12%. Increasing the length of the thinned out forward region 132 of the sole 110 reduces peak stress values in golf club head 100. Rather than behaving as a rigid connection, the undercut 102 generates stress relief at the face-sole transition by allowing the forward region 132 of the sole 110, between the strikeface 106 and the ballast 114, to deflect to a greater extent under impact loads. The effective increase in forward sole 132 length increases the total surface area over which impact load is distributed for a stress reduction of 1000 psi to 2000 psi within the forward region 132 of the sole. Undercut 102 both reduces stress concentrations within forward sole region 132 and increases the bending/spring effect of the forward sole region 132. Additionally, undercut 102 reduces peak stress values within the strikeface 106 by 2000 psi to 3500 psi. For example, the undercut can reduce peak stress values in the strikeface between 2000 psi to 2100 psi, 2100 psi to 2200 psi, 2200 psi to 2300 psi, 2300 psi to 2400 psi, 2400 psi to 2500 psi, 2500 psi to 2600 psi, 2600 psi to 2700 psi, 2700 psi to 2800 psi, 2800 psi to 2900 psi, 2900 psi to 3000 psi, 3100 psi to 3200 psi, 3200 psi to 3300 psi, 3300 psi to 3400 psi, or 3400 psi to 3500 psi.

Alone, the above decrease in stress, within the sole 110 and strikeface 106, can translate to an improved wear life of golf club head 100. In other words, golf club head 100 comprising ballast 114 with undercut 102 can be hit more times and played longer than a traditional golf club head without an undercut. For example, a hollow body golf club comprising an undercut 102 can have a failure count increase of 50 hits, 100 hits, 150 hits, 200 hits, 250 hits, or 300 hits. Fatigue failure in a cyclically loaded golf club occurs over time in locations of peak stress where small cracks form in the material. Cracks, in turn, amplify stress. Therefore, golf club head 100, with reduced peak stresses, experiences the crack growth and eventual fatigue failure at a slower rate.

Alternatively, the stress reduction achieved by the above ballast 114 and undercut 102 can be leveraged to improve club performance and ball speed. In some embodiments, the ballast 114 with undercut 102 can be provided in conjunction with a thinned strikeface 106. The extent to which the strikeface of a golf club head without the undercut 102 has been constrained by peak stress levels at the face-to-sole transition. Said another way, it is not possible to improve the performance of traditional golf clubs with a thinner face because the added stress from the thinner face results in peak stresses that exceed the critical K value. Golf club head 100, as discussed above, comprises ballast 114 with undercut 102 for stress reduction. Therefore, in some embodiments, strikeface 106 can be thinned without raising peak stress values beyond the critical K value at the sole-to-face transition.

The thickness can be reduced throughout the face. For example, at the geometric center of the face of the undercut club, the thickness at this region of the face can range between 0.080 to 0.150 inches. The thickness of the face at the geometric center of said face can be 0.150 inches, 0.140 inches, 0.130 inches, 0.120 inches, 0.110 inches, 0.100 inches, 0.090 inches, or 0.080 inches. In the perimeter toe region of the face of the undercut iron club, the thickness of the face can range from 0.050 to 0.090 inches. The thickness of the face at the perimeter toe region can be 0.050 inches, 0.060 inches, 0.065 inches, 0.070 inches, 0.071 inches, 0.074 inches, 0.076 inches, 0.077 inches, 0.079 inches, 0.080 inches, 0.082 inches, 0.084 inches, 0.086 inches, 0,088 inches, or 0.090 inches. The thickness of the face at the heel perimeter end of the undercut iron club can range from 0.045 inches to 0.090 inches. The thickness of the face at the heel perimeter end can be 0.045 inches, 0.050 inches, 0.055 inches, 0.060 inches, 0.065 inches, 0.070 inches, 0.075 inches, 0.080 inches, 0.085 inches, or 0.090 inches.

In some examples, the ballast 114 with undercut 102 reduces face thickness by 0.003 inches. In other examples the undercut 102 can allow the strikeface 106 to be thinned by 0.004 inches, 0.005 inches, 0.006 inches, 0.007 inches, 0.007 inches, 0.008 inches, 0.009 inches, or 0.010 inches. In an already thin strikeface 106, this reduction equates to a thinning of roughly 6%, or an increase in ball speed of 0.5 mph to 0.7 mph. In some examples, the undercut 102 allows the strikeface to be 3 to 8% thinner than the strikeface of a golf club head without an undercut. For example, the strikeface 106 can be 3% thinner, 4% thinner, 5% thinner, 6% thinner, 7% thinner, or 8% thinner.

As discussed above, the undercut region 128 has a volume representative of mass removed from ballast 114. Ballast 114 functions as a mass pad for controlling the center of gravity (CG) for golf club head 100, such that the undercut 102 can alter club head CG. The CG can be defined relative to a geometric center 126 of the strikeface 106. The geometric center 126 of the strikeface 106 can be determined in accordance with Section 6.1 of the USGA's Procedure for Measuring the Flexibility of a Golf Clubhead (USGA-TPX3004, Rev. 1.0.0, May 1, 2008) (available at http://www.usga.org/equipment/testing/protocols/Procedure-For-Measuring-The-Flexibility-Of-A-Golf-Club-Head/) (the “Flexibility Procedure”). A CG height can be defined as a vertical distance between the CG and the ground plane. A front-rear CG depth 144 can be defined as a horizontal distance between the geometric center 126 the CG. For example, the front-rear CG depth 144 can range from 0.080 to 0.110 inches. The front-rear CG depth can be 0.080 inches, 0.082 inches, 0.084 inches, 0.086 inches, 0.088 inches, 0.090 inches, 0.092 inches, 0.094 inches, 0.096 inches, 0.098 inches, 0.100 inches, 0.105 inches, or 0.110 inches.

A ratio of undercut face depth 131 to the front-rear CG position is constrained between 3.0 and 5.5. For example, the face depth ratio 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0. In this range, the undercut 102 improves peak stress within the forward sole region 132 without removing material from the ballast to the extent that CG position is compromised.

Furthermore, because of the CG position, the undercut does not affect the overall MOI of the club. For the purpose of determining club head moments of inertia, a coordinate system may be defined at the CG via mutually orthogonal axes (i.e., an x-axis, a y-axis, and a z-axis) (Figure not shown). The y-axis extends through the head CG from the top rail 112 to the sole 110, perpendicular to a ground plane when the golf club head 100 is at an address position. The x-axis extends through the head CG from the heel portion 103 to the toe portion 105 and perpendicular to the y-axis. The z-axis extends through the head CG from the strikeface 106 to the rearward region 108, and perpendicular to the x-axis and the y-axis.

Moments of inertia then exist about the x-axis Ixx (i.e. top rail-to-sole moment of inertia), about the y-axis Iyy (i.e. heel-to-toe moment of inertia) and about the z-axis (i.e. strikeface to rear). In many embodiments, the golf club head with undercut comprises a top rail-to-sole moment of inertia, Ixx, from 95 g·in2 to 130 g·in2. In many embodiments, the golf club head with undercut comprises a top rail-to-sole moment of inertia Ixx greater than approximately 95 g·in2, greater than approximately 98 g·in2, greater than approximately 100 g·in, greater than approximately 102 g·in2, greater than approximately 103 g·in2, greater than approximately 104 g·in2, greater than approximately 105 g·in2, greater than approximately 106 g·in2, greater than approximately 110 g·in2, greater than approximately 115 g·in2, greater than approximately 120 g·in2, greater than approximately 125 g·in2, greater than approximately 130 g·in2, greater than approximately 135 g·in2, greater than approximately 140 g·in2, greater than approximately 6750 g·in2, or greater than approximately 145 g·in2. Further, in many embodiments, the golf club head with undercut comprises a heel-to-toe moment of inertia Iyy, which may be greater than approximately 350 g·in2, greater than approximately 360 g·in2, greater than approximately 370 g·in2, greater than approximately 380 g·in2, greater than approximately 390 g·in2, greater than approximately 400 g·in2, greater than approximately 410 g·in2, greater than approximately 420 g·in2, or greater than approximately 430 g·in2. In many embodiments, the golf club head with undercut comprises a heel-to-toe moment of inertia Iyy from 350 g·in2 to 420 g·in2. Further, the golf club head with undercut comprises a strikeface to rear moment of inertia Izz, which may be greater than approximately 400 g·in2, greater than approximately 4100 g·in2, greater than approximately 420 g·in2, greater than approximately 430 g·in2, greater than approximately 440 g·in2, greater than approximately 450 g·in2, greater than approximately 460 g·in2, greater than approximately 470 g·in2, or greater than approximately 480 g·in2. In many embodiments, the golf club head with undercut comprises a strikeface to rear moment of inertia Izz from 400 g·in2 to 450 g·in2. The undercut of the golf club head does not significantly alter the moment of inertia of the Ixx, Iyy, and Izz axes over a golf club head without the undercut.

ii. Undercut Formed by Angled Forward Surface of Ballast

FIG. 4A illustrates a heel cut away view of an iron-type golf club head 300 comprising an alternative ballast 314 design forming an undercut 302. The golf club head 300 is substantially similar to golf club head 100, but for the difference in the geometry of the ballast 314 and the undercut 302. The ballast 314 is a solid structure located within the internal cavity 304 protruding vertically from the sole 310, forward from the rearward region 308, and extending along the sole 310 in a heel to toe direction. A forward region 332 of the sole 310 is defined between the strikeface 306 and the ballast 314. The ballast 314 extends forward from the rearward region 308 towards the strikeface 306 and positions mass low and forward in the internal cavity 304.

As illustrated in FIG. 4A, the ballast 314 comprises a top surface 316, a forward surface 318, and a ballast juncture 317 forming a transition between the top surface 316 and the forward surface 318. The ballast 314 does not form a bottom surface. The ballast forward surface 318 transitions directly into the sole 310. As illustrated in FIG. 4B, an undercut juncture 330 is formed at the transition between the forward surface 318 and the sole 310.

Referring to FIGS. 4A and 4B, the ballast forward surface 318 is angled with respect to the forward region 332 of the sole 310. The ballast 314 forms an acute angle 399 between the ballast forward surface 318 and the interior surface 322 of the sole 310. The ballast angle 399 creates a configuration in which the ballast juncture 317 is located forward of the undercut juncture 330 and at least a portion of the ballast 314 extends forward relative to the undercut juncture 330 to overhang the forward sole region 332. Specifically, the ballast forward surface 318 overhangs at least a portion of the forward sole region 332. The angled configuration of the ballast 314 distributes mass low in the golf club head 300 without compromising the length of the forward sole region 332. In this way, the club head CG height can be lowered without a reduction in spring energy stored within the forward sole region 332.

In many embodiments, the ballast angle 399 between the ballast forward surface 318 and interior surface 322 of the sole 310 can be between approximately 30 degrees and approximately 80 degrees. In some embodiments, the ballast angle 399 can be between 30 and 50 degrees, 35 and 55 degrees, 40 and 60 degrees, 45 and 65 degrees, 50 and 70 degrees, 55 and 75 degrees, or 60 and 80 degrees. In some embodiments, the ballast angle 399 can be less than 80 degrees, less than 75 degrees, less than 70 degrees, less than 65 degrees, less than 60 degrees, less than 55 degrees, less than 50 degrees, less than 45 degrees, less than 40 degrees, less than 35 degrees, or less than 30 degrees.

The ballast angle 399 can be selected to allow ballast 314 to project substantially forward toward the strikeface 306. The smaller the ballast angle 314, the greater the ability of the ballast 314 to position mass low and forward, which provides a more desirable CG location.

Referring to FIG. 4B, the angled ballast 314 defines an undercut 302 extending beneath the ballast 314. The undercut 302 is formed between the ballast forward surface 318 and the interior surface 322 of the sole 310. The undercut 302 can be defined as the volume of the internal cavity 304 that is both beneath the ballast forward surface 318 and above the forward region 332 of the sole 310. In the illustrated embodiment, the ballast forward surface 318 forms a top edge 337 of the undercut 302, and the sole interior surface 322 forms a bottom edge 339 of the undercut 302. The undercut 302 can further be defined as the volume bounded between the undercut top edge 337 and the undercut bottom edge 339 over a heel to toe length 324 of the ballast 314. In the illustrated embodiment, referring to FIG. 4B, an opening between the undercut 302 and the remainder of the internal cavity 304 is formed along a ballast forward plane 350, wherein the ballast forward plane 350 is tangent to the ballast juncture 317 and extends parallel to the strikeface 306. The ballast forward plane 350 defines a forwardmost boundary of the undercut 302, and the undercut juncture 330 forms a rearmost point of the undercut 302.

Similar to undercut 102, the undercut 302 formed by the angled ballast 314 effectively lengthens the forward region 332 of the sole 310. The undercut 302 not only reduces stress in the forward sole region 332, but also creates a larger spring by lengthening the amount of thin sole 310 material that is configured to flex. This larger spring increases the amount of energy transferred back to the ball at impact.

Referring to FIG. 4B, the undercut 302 comprises an undercut depth 334, an undercut height 336, and an undercut length (not shown). The undercut depth is measured as a perpendicular distance between a ballast forward plane 350 and the undercut juncture 330 (i.e., the rear most point of the undercut). The undercut height 336 is defined as the vertical distance between an undercut top edge 337 and an undercut bottom edge 339. The undercut length (not shown) is measured parallel to a ground plane between the undercut toe end 133 and the undercut heel end 135. Finally, the undercut sole thickness is measured as the perpendicular distance from the exterior surface of the sole 321 and the sole interior surface 332.

In many embodiments, the undercut depth 334 between the ballast forward plane 350 and the undercut juncture 330, can range between 0.010 inch and 0.300 inch. In some embodiments, the undercut depth 134 can range from 0.010 inch to 0.030 inch, 0.030 inch to 0.050 inch, 0.050 inch to 0.070 inch, 0.070 inch to 0.090 inch, 0.090 inch to 0.110 inch, 0.110 inch to 0.130 inch, 0.130 inch to 0.150 inch, 0.150 inch to 0.170 inch, 0.170 inch to 0.190 inch, 0.190 inch to 0.210 inch, 0.210 inch to 0.230 inch, 0.230 inch to 0.250 inch, 0.250 inch to 0.270 inch, 0.270 inch to 0.290 inch, or 0.290 inch to 0.300 inch. In some embodiments, the undercut depth 134 can be greater than approximately 0.010 inch, greater than approximately 0.015 inch, greater than approximately 0.020 inch, greater than approximately 0.025 inch greater than approximately 0.05 inch, greater than approximately 0.075 inch, greater than approximately 0.100 inch, greater than approximately 0.125 inch, greater than approximately 0.150 inch, greater than approximately 0.175 inch, greater than approximately 0.200 inch, greater than approximately 0.225 inch, greater than approximately 0.250 inch, greater than approximately 0.275 inch, or greater than approximately 0.300 inch.

In many embodiments, the undercut height 336, measured between the undercut bottom edge 339 and undercut top edge 337, can range from approximately 0.030 inch to approximately 0.500 inch. In some embodiments, the undercut height 336 can range from 0.030 inch to 0.050 inch, 0.050 inch to 0.070 inch, 0.070 inch to 0.090 inch, 0.090 inch to 0.110 inch, 0.110 to 0.130 inch, 0.130 inch to 0.150 inch, 0.150 inch to 0.170 inch, 0.170 inch to 0.190 inch, 0.190 inch to 0.210 inch, 0.210 to 0.230 inch, 0.230 inch to 0.250 inch, 0.250 inch to 0.270 inch, 0.270 inch to 0.290 inch, 0.290 inch to 0.310 inch, 0.310 to 0.330 inch, 0.330 inch to 0.350 inch, 0.350 inch to 0.370 inch, 0.370 inch to 0.390 inch, 0.390 inch to 0.410 inch, 0.410 inch to 0.430 inch, 0.430 inch to 0.450 inch, 0.450 inch to 0.470 inch, or between 0.470 inch and 0.500 inch. In some embodiments, the undercut height 336 can be greater than approximately 0.010 inch, greater than approximately 0.015 inch, greater than approximately 0.020 inch, greater than approximately 0.025 inch, greater than approximately 0.05 inch, greater than approximately 0.075 inch, greater than approximately 0.100 inch, greater than approximately 0.125 inch, greater than approximately 0.150 inch, greater than approximately 0.175 inch, greater than approximately 0.200 inch, greater than approximately 0.225 inch, greater than approximately 0.250 inch, greater than approximately 0.275 inch, greater than approximately 0.300 inch, greater than approximately 0.325 inch, greater than approximately 0.350 inch, greater than approximately 0.375 inch, greater than approximately 0.400 inch, greater than approximately 0.425 inch, greater than approximately 0.450 inch, greater than approximately 0.475 inch, or greater than approximately 0.500 inch.

Due to the angled nature of the ballast 314, the undercut height 336 can vary in a front to rear direction. The ballast juncture 317, which forms the forwardmost extent of the undercut top edge 337, is also the highest point of the undercut top edge 337. Accordingly, in many embodiments, the undercut height 336 decreases in a front to rear direction, with the undercut height 336 being greatest at the ballast forward plane 350 and smallest at the undercut juncture 330.

In many embodiments, the undercut 302 comprises an undercut length (not shown) similar to the length 138 of undercut 102. The undercut length is measured between the undercut heel end 335 and the undercut toe end 337. In many embodiments, the length of undercut 302 can range from 0.5 inch to 3.0 inches. In some embodiments, the length of undercut 302 can range from 0.50 inch to 0.75 inch, 0.75 inch to 1.00 inch, 1.00 inch to 1.25 inches, 1.25 inches to 1.50 inches, 1.50 inches to 1.75 inches, 1.75 inches to 2.00 inches, 2.00 inches to 2.25 inches, 2.25 inches to 2.50 inches, 2.50 inches to 2.75 inches, or 2.75 inches to 3.00 inches. In some embodiments, the length of undercut 302 can be greater than 0.5 inch, greater than 0.75 inch, greater than 1.0 inch, greater than 1.25 inches, greater than 1.50 inches, greater than 1.75 inches, greater than 2.0 inches, greater than 2.25 inches, greater than 2.50 inches, greater than 2.75 inches, or greater than 3.0 inches.

In some embodiments, referring to FIG. 5, the ballast forward surface 318 can define a curvature in a heel to toe direction. In many embodiments, such as the embodiment illustrated in FIG. 5, the ballast forward surface 318 comprises a concave curvature relative to the strikeface 306. In such embodiments, the ballast forward surface 318 is closer to the strikeface 306 near the heel portion 303 and the toe portion 305 than near the center of the golf club head 300. The concave configuration of the ballast forward surface 318 effectively lengthens the forward sole region 332 near the center of the golf club head in comparison to forward sole region 332 near the heel portion 303 and the toe portion 305. Because iron-type golf club heads typically experience peak stresses in the center of the club head and lower stresses near the heel and toe, the forward sole region 332 can be shortened near the heel portion 303 and the toe portion 305 without sacrificing durability.

The concave configuration of the ballast forward surface 318 allows portions of the ballast 314 near the heel portion 303 and the toe portion 305 to extend further towards the strikeface 306. This configuration allows the overall mass of the ballast 314 to be placed lower and further forward in the internal cavity 304. Providing the ballast forward surface 318 with a concave curvature in a heel to toe direction allows the CG of the golf club head 300 to be controlled without sacrificing the durability of the forward sole region 332. In many embodiments, the curvature of the ballast forward surface 318 can be configured to complement the geometry of a cascading sole region (discussed in further detail below) or any other stress relieving feature included in the forward sole region 332.

B. Undercut and Cascading Sole

FIG. 6A illustrates another embodiment of a golf club head 200 comprising a ballast 214, undercut 202, and a cascading forward region 232 of the sole 210. FIG. 6A depicts a cross-sectional view of golf club head 200. Golf club head 200 is substantially similar to golf club head 100 and comprises a thin forward region 232 of sole 210 that has been effectively lengthened via the undercut 202. Golf club head 200 is further defined by a strikeface 206, a rearward region 208 opposite the strikeface 206, a heel portion 203, a toe portion 205 opposite the heel portion 203, a sole 210, and a top rail 212 opposite the sole 210. Together, these components define a hollow body club with an interior cavity 204. The rearward region 208 further comprises a ballast 214 located within the internal cavity 204. As shown in FIG. 6A, the ballast 214 comprises the top surface 216, the forward surface 218, and the bottom surface 220. Ballast bottom surface 220 is similar to ballast bottom surface 120. The contoured bottom surface 220 is indented toward the rearward region 208 to create undercut 202.

FIG. 6B is an enlarged view of the ballast 214 and sole 210 illustrated in FIG. 6A. As shown, the forward region 232 of the sole 210 extends from the undercut 202 in ballast 214 to the strikeface 206. The forward region 232 of the sole further comprises an inner region 260 and a cascading region 262. The cascading region 262 can comprise an internal radius transition 264 between an internal surface of the strikeface 206 and an internal surface of the sole 210. The cascading region 262 can comprise at least two thickness tiers, or levels. The tiered structure creates successive thinning of the forward sole region 132. In some embodiments, the cascading region 262 can comprise an internal radius transition 264 having 2, 3, 4, 5, 6, or 7 tiers.

Continuing to refer to FIG. 6B, the cascading region 262 comprises a first tier 266, second tier 268, and a tier transition 270 between the first tier 266 and second tier 268. The cascading region 262 of the forward sole region 232 can have a thickness measured as the perpendicular distance between the exterior surface 221 of the sole and interior surface 222 of the sole. This thickness can decrease in a front to rear direction over the cascading region 262. The first tier 266 can have a first thickness 272 defined as the perpendicular distance between the exterior surface 221 and interior surface 222 of the sole within the first tier 266. The second tier 268 can have a second thickness 274 defined within the second tier 268 as the perpendicular distance between the exterior surface 221 and interior surface 222 of the sole. In some embodiments, the first thickness 272 is greater than the second thickness 274, such that the overall thickness of the cascading region 262 decreases in the front to rear direction. The first thickness 272 and/or the second thickness 274 can have a constant thickness over a tier length in the front to rear direction. In other embodiments, the first thickness 272 and/or the second thickness 274 can be sloped to decrease in thickness over the tier length in the front to rear direction.

The cascading region can comprise a first tier 266, second tier 268, a third tier (not shown), and a first tier transition 270 between the first tier 266 and second tier 268, and a second tier transition between the second tier and the third tier. As described above, the cascading region of the forward sole region with three tiers can have a thickness measured as the perpendicular distance between the exterior surface of the sole and interior surface of the sole. Again, the thickness decreases in a front to rear direction over the cascading region. As described above, the first tier can have a first thickness. The second tier can have a second thickness. The third tier can have a third thickness, wherein the third tier thickness (like the first and second tier thicknesses) is measured as the perpendicular distance between the exterior surface and interior surface of the sole. In some embodiments, the first thickness is greater than the second thickness, and in turn, the second thickness is greater than the third thickness, such that the overall thickness of the cascading region 262 decreases in the front to rear direction. The first thickness and/or the second thickness and/or third thickness can have a constant thickness over a tier length in the front to rear direction. In other embodiments, the first thickness and/or the second thickness and/or third thickness can be sloped to decrease in thickness over the tier length in the front to rear direction.

The tier transition 270, between a rear edge of the first tier and a forward edge of the second tier, can be declined in a front to rear direction to steadily decrease the cascading region thickness between the first thickness 272 and second thickness 274. Alternatively, in a cascading region with two tier transitions (i.e., a first transition between the first tier and second tier, and a second transition between the second tier and third tier), the transitions can be declined in a front to rear direct to steadily decrease the cascading region thickness between the first thickness, second thickness and third thickness (or first tier, second tier and third tier). In some embodiments, such as FIG. 6B, the tier transition 270 is linearly declined at an angle less than 45 degrees between adjacent first 266 and second tiers 268. In some embodiments, the tier transition 270 is linearly declined at an angle ranging between 10 degrees and less than 45 degrees. The linear decline can be gradual between 5 degrees and 10 degrees, 10 degrees and 15 degrees, 15 degrees and 20 degrees, 20 degrees and 25 degrees, 25 degrees and 30 degrees, 30 degrees and 40 degrees, or 40 degrees and 45 degrees. In other embodiments, not shown, the tier transition 270 can be a steeper, and more like a step. For example, tier transition 270 can be between 45 and 50 degrees, 50 degrees and 55 degrees, 55 degrees and 60 degrees, 60 degrees and 65 degrees, or 65 degrees and 70 degrees.

As mentioned above, the forward sole region 232 further comprises inner region 260 between the cascading region 262 and ballast undercut 202. The uniform inner region 260 also comprises an inner thickness 276 defined as the perpendicular distance between the exterior surface 221 of the sole 210 and the inner surface 222 of the sole 210. The inner thickness 276 is less than the thickness of an adjacent tier, or final tier within the cascading region 262. As shown in FIG. 6B, the inner thickness 276 is less than the second thickness 274.

In many embodiments, the cascading region 262 comprising at least a first tier 266 and second tier 268, and alternatively a third tier (not numbered) can comprise a specific profile configured to efficiently relieve stress within the forward sole region 232. FIG. 7 illustrates one embodiment of a profile of the cascading region 262. The cascading region 262 can comprise a perimeter separating the cascading region 262 from the inner region 260 (which forms the remainder of the forward sole region 232).

In the illustrated embodiment of FIG. 7, the perimeter of the cascading region 262 comprises a cascade front edge 279, a cascade rear edge 281, a cascade toe edge 280, and a cascade heel edge 282. The cascade front edge 279 extends in a heel to toe direction and is located proximate a leading edge 215 of the strikeface 206. The cascade rear edge 281 extends in a heel to toe direction and is spaced rearwardly from the cascade front edge 279. The cascade toe edge 280 extends between the cascade front edge 279 and the cascade rear edge 281 near the toe portion 205. The cascade heel edge 282 extends between the cascade front edge 279 and the cascade rear edge 281 near the heel portion 203.

In many embodiments, as illustrated in FIG. 7, the cascade rear edge 281 can be arcuate, such that the cascade rear edge 281 comprises a curvature as it extends in the heel to toe direction. In the illustrated embodiment of FIG. 7, the cascade rear edge 281 bows rearward relative to the strikeface 206. As such, the cascade rear edge 281 is spaced further from the strikeface 206 near the center of the golf club head 200 than near the heel portion 203 and the toe portion 205. In many embodiments, the cascade front edge 279 is generally parallel to the strikeface 206. In such embodiments, the arcuate cascade rear edge 281 is therefore also bowed rearward relative to the cascade front edge 279.

In some embodiments, as illustrated in FIG. 7, one or more of the plurality of tiers 266, 268, 269 can substantially match the curvature of the arcuate rear edge 281. One or more of the plurality of tiers can be bowed rearward relative to the cascade front edge 279 and/or the strikeface 206. In some embodiments wherein the ballast forward surface 218 comprises a curvature in a heel to toe direction, the curvature of the arcuate cascade rear edge 281 may substantially match the curvature of the ballast forward surface 218. The cascading region 262 can comprise a cascading region depth 290 and a cascading region width 292. Referring to FIG. 7, the cascading region depth 290 is the distance between the cascade front edge 279 and the cascade rear edge 281, measured perpendicular to the strikeface 206. In many embodiments, the cascading region depth 290 can range between 0.050 inch and 0.250 inch. In some embodiments, the cascading region depth 290 can be between 0.050 inch and 0.075 inch, between 0.075 inch and 0.100 inch, between 0.100 inch and 0.125 inch, between 0.125 inch and 0.150 inch, between 0.150 inch and 0.175 inch, between 0.200 inch and 0.225 inch, or between 0.225 inch and 0.250 inch. In some embodiments, the cascading region depth 290 can be greater than 0.050 inch, greater than 0.075 inch, greater than 0.100 inch, greater than 0.125 inch, greater than 0.150 inch, greater than 0.175 inch, greater than 0.200 inch, greater than 0.225 inch, or greater than 0.250 inch. In some embodiments, the cascading region depth can be approximately 0.125 inch, 0.130 inch, 0.135 inch, 0.140 inch, 0.145 inch, 0.150 inch, 0.155 inch, 0.160 inch, 0.165 inch, 0.170 inch, or 0.175 inch. In some embodiments, the cascading region depth 290 can be substantially constant in a heel to toe direction. In many other embodiments, such as described below, the cascading region depth 290 can vary in a heel to toe direction.

In the illustrated embodiment of FIG. 7, wherein the cascading region 262 comprises a rearward bowing cascade rear edge 281, the cascading region depth 290 is greatest proximate the center of the forward sole region 232 and lesser near the cascade heel edge 282 and cascade toe edge 280. In many embodiments, cascading region depth 290 at the cascade heel edge 282 and/or the toe edge 280 can be between 50% and 95% than the maximum cascading region depth 290. In some embodiments, the cascading region depth 290 at the cascade heel edge 282 and/or the cascade toe edge 280 can be between 50% and 60%, between 60% and 70%, between 70% and 80%, between 80% and 90%, or between 90% and 95% the maximum cascading region depth 290. In some embodiments, the cascading region depth 290 can be less than 95%, less than 90%, less than 85%, less than 80%, less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, or less than 50% of the maximum cascading region depth 290. In many embodiments, such as the illustrated embodiment of FIG. 7, the maximum cascading region depth 290 is located at or near the center of the forward sole region 232.

The increased cascading region depth 290 near the center of the forward sole region 232 allows the cascading region 262 to relieve peak stresses that commonly occur near the center of golf club head 200. Similarly, in embodiments with arcuate tiers (such as the illustrated embodiment of FIG. 7), each tier bows rearward near the center of the golf club head 200, contributing to the relief of peak stresses occurring near center. Because the stress experienced in the forward sole region 232 is not as severe near the heel portion 203 and the toe portion 205, the cascading region 262 can comprise a lesser depth 290 near the cascade heel edge 282 and the cascade toe edge 280 and still be able to relieve such stresses. Shortening the cascading region depth 290 near the cascade heel edge 282 and the cascade toe edge 280 allows the uniform inner region 260 to be effectively lengthened near the heel portion 203 and the toe portion 205. Effectively lengthening the uniform inner region 260, which has a lesser thickness than any tier within the cascading region 262, increases the bending/spring effect of the forward sole region 232.

Referring to FIG. 7, the cascading region width 292 is the distance between the cascade heel edge 282 and the cascade toe edge 280, measured in a heel to toe direction (i.e. parallel to the strikeface 206). In many embodiments, the cascading region width 292 can range between 0.50 inch and 2.5 inches. In some embodiments, the cascading region width 292 can be between 0.50 inch and 0.75 inch, between 0.75 inch and 1.00 inch, between 1.00 inch and 1.25 inch, between 1.25 inch and 1.50 inch, between 1.50 inch and 1.75 inch, between 2.00 inch and 2.25 inch, or between 2.25 inch and 2.50 inch. In some embodiments, the cascading region width 292 can be greater than 0.50 inch, greater than 0.75 inch, greater than 1.00 inch, greater than 1.25 inch, greater than 1.50 inch, greater than 1.75 inch, greater than 2.00 inch, greater than 2.25 inch, or greater than 2.50 inch. In some embodiments, the cascading region width 292 can be less than 2.50 inches, less than 2.25 inches, less than 2.00 inches, less than 1.75 inches, less than 1.50 inches, less than 1.25 inches, or less than 1.00 inches. In some embodiments, the cascading region width 292 can be approximately 1.25 inches, 1.30 inches, 1.35 inches, 1.40 inches, 1.45 inches, 1.50 inches, 1.55 inches, 1.60 inches, 1.65 inches, 1.70 inches, or 1.75 inches. In some embodiments, the cascading region width 292 can be substantially constant in a front to rear direction. In many other embodiments, such as described below, the cascading region width 292 can vary in a front to rear direction.

In some embodiments, the cascade heel edge 282 and the cascade toe edge 280 can extend substantially perpendicular to the strikeface 206, such that the cascading region width 292 is constant. In many embodiments, such as the embodiment illustrated in FIG. 7, cascade heel edge 282 and the cascade toe edge 280 are shaped to converge inwards such that the width 292 of the cascading region 262 is tapered in a front to rear direction. In such embodiments, the cascading region width 292 is greatest proximate the cascade front edge 279 and lesser near the cascade rear edge 291.

Similar to the variable cascading region depth 290, the tapering of the cascading region width 292 allows the uniform inner region 260 to be effectively lengthened near the heel portion 203 and the toe portion 205. The increased cascading region width 292 near the cascade front edge 279 allows the cascading region 262 to relieve peak stresses that commonly occur at the forwardmost portions of the forward sole region 232. Because the stress experienced in the forward sole region 232 is not as severe rearward of the strikeface 206, the cascading region 262 can comprise a lesser width 292 near the cascade rear edge 281 without sacrificing durability. The tapering of the cascading region width 292 in a front to rear direction effectively lengthens the uniform inner region 260 and increases the bending/spring effect of the forward sole region 232.

Continuing to refer to FIG. 6B, the inner region 260 of forward sole region 232 can be effectively lengthened by ballast 214 comprising undercut 202. Ballast 214 is substantially similar to the geometry of ballast 114. Ballast bottom surface defines an undercut region 228 comprising the undercut 202, undercut transition 241, and undercut juncture 230. As shown in FIG. 6B, the inner region 260 is positioned adjacent undercut 202. The undercut region 228 functions in a substantially similar manner as undercut 202 and undercut region 228. Specifically, undercut region 228 also reduces stress concentrations within forward sole region 232 and increases the bending/spring effect of the forward sole region 232. The cascading region 262 can be combined with any undercut or ballast geometry described above, including an undercut 102 formed by the bottom surface 120 of a ballast 114 or an undercut 302 formed by an angled forward surface 318 of a ballast 314.

In many embodiments, performance improvements from the cascading region 262 and the undercut 202 are compounding. In other words, golf club heads having both a cascading region and undercut 202, such as hollow body club head 200, have a greater reduction in peak stress than golf club heads comprising one of a cascading region or an undercut. Reduction of peak stress within forward sole region 232 increases the region's tolerance to modifications for improving ball speeds. Specifically, hollow body club 200 comprising forward sole region 232, which is defined by undercut 202 and comprising cascading region, can comprise a thinner face (as compared to a hollow body club lacking either or both of the undercut and cascading sole). This results in better ball speeds and flight distance. In some embodiments, the undercut 202 and cascading sole 242 allow the forward region of the sole 232 to be made more reactive. Rather than remaining rigid, the forward region 232 can be thinned, such that the forward region 232 behaves as a spring under impact loads. This means that the golf club head 200 is more efficient at transferring swing energy to the golf ball. The ultimate increase in ball speed via reduction in average thickness of the forward region 232 of the sole is the result of stress reduction at the face-to-sole transition 226. The undercut and the cascading sole work together to improve the flow of stress within the forward region 232, thereby reducing stress concentration levels at impact.

C. Additional Features

i. Support Member

Golf club heads comprising a support member spanning across a rear opening to enhance the structural rigidity and improves vibrational response and face flexure are shown in FIGS. 15-33, 34C-34F, 43, and 46. In these embodiments, the golf club heads can comprise many of the features described above, such as an overhanging mass pad (ballast), undercut, and cascading sole. As described above, the undercut and cascading sole increase face flexure and improve stress flow around the strike face. The undercut and cascading sole face thickness to be reduced by approximately 3-8% thinner than a club head without these features. However, undesirable vibrational responses may arise from the thin-wall construction throughout the club head body. To mitigate these vibrations, the golf club heads may additionally include a support member that spans across a rear opening to enhance structural rigidity along the perimeter of the club head, effectively damping vibrations without negatively impacting the improved face flexure and mass properties derived from the ballast, undercut, and cascading sole. Furthermore, the support member provides consistent launch characteristics by preventing undesired dynamic flexing. The support member improves distance control and shot dispersion compared to hollow body club heads without a support member. Thus, the support member operates in conjunction with the aforementioned features to enhance the frequency, sound response, and launch characteristics of the club head upon impact with a golf ball.

The back of the golf club has a top rail, a bottom rail, a heel rail, and a toe rail that together form a rear opening of the golf club head. The support member connects at least two of these structures forming the golf club head rear opening to provide stability, stiffness, and sound control to the golf club head. For example, in the illustrated embodiments, the support member connects the top rail to the bottom rail of the rear opening in a vertical direction, or connects the top rail of the rear opening to the toe rail of the rear opening in an angled direction. In other embodiments, the support member may extend from the top rail to the heel rail, heel rail to the toe rail, bottom rail to the heel rail, or bottom rail to toe rail of the rear opening. The support member can connect to any desired portion of the rear opening to selectively damp specific portions of the rear opening that experience high vibrational or frequency response.

In some embodiments, the club head can comprise one support member extending across a rear opening, dividing the rear opening into two openings. In other embodiments, the club head can comprise two or more support members extending across the rear openings. The two or more support members may be separated or intersect at one or more points, creating more than two openings.

The enclosed cavity, as defined by the inner walls of the club head body and the inner surface of the insert, comprises a cavity volume ranging from about 10 cc to 50 cc. The illustrated embodiment has a cavity volume of about 20 cc. In other embodiments, the volume of the interior cavity ranges from 10 cc to 12 cc, from 12 cc to 14 cc, 14 cc to 16 cc, from 16 cc to 18 cc, from 18 cc to 20 cc, from 20 cc to 24 cc, from 24 cc to 28 cc, from 28 cc to 32 cc, from 32 cc to 40 cc, or from 40 cc to 50 cc.

A golf club head body 300 having a single support member extending between the toe and top rail to improve vibrational response and launch characteristics is illustrated in FIGS. 15-19. The golf club head body 300 comprises a strike face 306, an insert 307, and a support member 350. The golf club head 300 further comprises a toe end 305, a heel end 303, a top rail 312, a sole 310, and a rear 308. The rear 308 further comprises a lap joint 311 extending around a perimeter of the rear 308 and defining a rear opening 309. The strike face 306, toe end 305, heel end 303, top rail 312, sole 310, and rear 308 together define an internal cavity 304 or rear cavity (also called an exposed cavity). The internal cavity 304 can be exposed through the rear opening 309. In some embodiments, there can be two or more rear openings.

The one or more rear openings 309 can cross or cover greater than 20% of a total surface area of the rear 308 of the club head 300. In some embodiments, the one or more openings 309 cover between 20% and 100%. For example, in some embodiments, the rear opening 309 can form between 20% to 30%, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, or 90% to 100% of a surface area of the rear 308 of the club head 300. In the illustrated embodiment of FIGS. 15-19, the rear opening 309 covers at least 75% of the surface area of the rear 308 of the club head 300.

The support member 350 spans the rear opening 309 and connects at least two portions of the lap joint 311. The support member 350 can cooperate with the innermost perimeter portion of the rear to partially define at least two rear openings. In some embodiments, the support member 350 can be integral with the club head 300, such that the support member 350 is the same material as, and cast with, forged with, or otherwise integrally formed with, the club head 300. The support member 350 can provide structural support to the rear wall and top rail 312 of the club head 300. Specifically, the support member 350 can target regions along club head body which experience greater movement and flex upon impact, such as the top rail. The support member can connect the top rail to at least one portion of the rear wall. In other embodiments, the support member 350 can connect to an area on the rear wall near the top rail 312, to at least one other portion of the rear opening 309 or lap joint 311. In the illustrated embodiment, the support member 350 comprises a first end 352 that connects to a top rail portion of the lap joint 311 and a second end 354 that connects to a lower toe portion of the lap joint 311. The support member 350 can be angled such that the first end 352 is located more heelward than the second end 354 of the support member 350. In other words, the support member 350 extends in a toeward direction from the top rail 311, or an area on the rear wall near the top rail 311, to an area on the rear wall near the sole portion. Areas of the club head 300 without structural support, such as the top line and areas surrounding the rear cavity, can create suboptimal frequencies in these areas leading to poor feel, sound, and launch characteristics. The support member 350 provides support to these areas, thereby leading to preferable club head characteristics at impact, such as sound and feel. In other embodiments, the support member 350 can connect to the top rail and other portions of the rear wall or lap joint. For example, the support member 350 can connect to the top rail and the toe portion and/or the top rail and the heel portion. Furthermore, the support member can also connect to three or more portions of the rear wall and top rail.

The support member 350 further comprises a thickness measured as the distance between an exterior surface (rear surface) to an interior surface (front surface) of the support member 350, in a front to back direction. The thickness of the support member 350 can range from approximately 0.030 inch to 0.250 inch. For example, in some embodiments, the thickness can range from 0.030 inch to 0.043 inch, 0.043 inch to 0.056 inch, 0.056 inch to 0.069 inch, 0.069 inch to 0.082 inch, 0.082 inch to 0.095 inch, 0.095 inch to 0.108 inch, 0.108 inch to 0.121 inch, 0.121 inch to 0.134 inch, 0.134 inch to 0.147 inch, 0.147 inch to 0.160 inch, 0.160 inch to 0.173 inch, 0.173 inch to 0.186 inch, 0.186 inch to 0.199 inch, 0.199 inch to 0.212 inch, or from 0.212 inch to 0.250 inch.

The thickness can be approximately constant throughout the length of the support member 350, or the thickness can vary along the length. For example, in some embodiments, the thickness of the support member 350 can be thinner at the top portion of the support member 350 nearest the top rail and thicker on the bottom portion of the support member nearest the sole. Alternatively, the thickness of the support member 350 or the support member can be thicker at the top portion of the support member 350 nearest the top rail and thinner on the bottom portion of the support member 350 nearest the sole.

The golf club head 300 further comprises an insert 307 configured to cover the rear opening 309, and enclose the internal cavity 304. The insert 307 can cooperate with or abut the rear surface of the support member 350. The lap joint 311 and the support member 350 can receive the insert 307, thereby closing off the rear cavity. In many embodiments, the insert does not extend beyond the lap joint 311. In most embodiments, the insert 307 is secured to the club head 300 with epoxy or other adhesive material. In other embodiments, the insert can be secured to the club head body using mechanical fastening means such as screws, snap hooks, press fitting, etc. In further embodiments, the insert can be secured using a combination of both an adhesive and mechanical fastening means. Furthermore, recessed region(s) of the insert 307 can be disposed within the rear openings between the innermost perimeter portion of the rear wall and the support member 350.

The insert 307 comprises a channel 313 defining a recess configured to receive the support member 350. The channel 313 has complementary geometry to the support member 350 and completely covers the support member 350 such that the support member 350 cannot be viewed from an exterior viewpoint of the club head 300. The channel 313 can be adhered to the support member 350, in addition to the lap joint 311, to increase bonding between the insert 307 to the club head 300.

The insert 307 can be formed from a polymer or flexible material with a low shore durometer (i.e., soft material) to improve feel and sound of the club through impact, and to seal the interior cavity to prevent water or debris from intruding into the interior cavity. The insert can be formed from a polymer matrix. The polymeric matrix can comprise glass-filled elastomer, a stainless steel-filled elastomer, a tungsten-filled elastomer, a thermoplastic polyurethane (TPU) composite, a thermoplastic elastomer (TPE) composite, or any other elastomer matrix composite, a Kevlar® (aramid) fiber-reinforced polymer, a carbon-fiber reinforced polymer, rubber, ethylene-vinyl acetate foam, polymer-based foam, any combination of a suitable resin and a suitable reinforcing fiber, or any combination of the above materials. Soft or flexible materials improve the feel and sound of the golf club head through impact.

A golf club head 400 having two support members is shown at FIGS. 20 and 21. The club head 400 has a similar construction to the club head 300 illustrated in FIGS. 15-19 and comprises similar features such as a ballast 414, an undercut 402, a cascading sole, a strike face, and an insert 404. The golf club head 400 differs from the golf club head 300 above in that the golf club head 400 comprises a heel support member 450 and a toe support member 455. The golf club head 400 further comprises an inflection seam 411 extending across the rear of the club head in a heel-toe direction. The inflection seam 411 divides the rear of the club head 400 into an upper rearward region 418 and a lower rearward region 416. The upper rearward region 418 entirely contains the insert 404 and the heel support member 450 and the toe support member 455. The lower rearward region 416 comprises a smooth continuous surface to form a muscle back appearance for the lower half of the club head 400.

In some embodiments, the inflection seam 411 can be located closer to the top rail 409 than the sole. The location of the inflection seam 411 adjusts mass properties by providing a distinct transition between an area of greater mass (the lower rearward region) and an area of relatively lesser mass (upper rearward region). Furthermore, the inflection seam 411 can improve face flexure and club head body bending dynamics by facilitating bending of the rear wall. In other embodiments, the inflection seam 411 can be located closer to the sole than the top rail 409. In further embodiments, the inflection seam 411 can match the contour of the top rail 409 and/or sole. In other embodiments, the inflection seam 411 can be substantially linear or curvilinear. Furthermore, the lap joint that defines the rear opening can span along any combination of the lower rearward region 416, inflection seam 411, and upper rearward region 418. In some embodiments, the lap joint can be isolated within the upper rearward region 418, inflection seam 411, or lower rearward region 416. In other embodiments, the lap joint can only span along the upper rearward region 418 and inflection seam 411, or the lower rearward region 416 and the inflection seam 411. In further embodiments, the lap joint can span along the upper rearward region 418, inflection seam 411, and the lower rearward region 416.

The toe support member 455 and heel support member 450 are positioned to reduce vibration response at impact. In the example shown in FIGS. 20 and 21, the toe support member 455 and the heel support member 450 extend from the bottom of the rear opening to the top rail 409. The toe support member 455 extends upwardly from the bottom toe portion of the rear opening to the top central portion of the rear opening. Similarly, the heel support member extends upwardly from the bottom heel portion of the rear opening to the top central portion of the rear opening. In the illustrated embodiment, the toe support member 455 and heel support member 450 converge and intersect at a top central location in the top rail 409. In other embodiments, the toe and heel support members do not have to converge or meet and may connect to different portions of the top rail 409. In other embodiments, the heel support member and toe support member can have other various configurations to connect different portions of the rear opening. In the illustrated embodiment, the support members 455, 450 are integrally formed and cast with the club head 400 such that the support members 455, 450 are the same material as the club head body.

The heel support member 450 and toe support member 455 extend at an angle across the rear opening. The angle is measured from a vertical midplane to an axis of each support members 450, 455. The support members 450, 455 can have an angle ranging from about 10 degrees to about 80 degrees. In some embodiments, the angle can range from 10 to 20 degrees, 20 to 30 degrees, 30 to 40 degrees, 40 to 50 degrees, 50 to 60 degrees, 60 to 70 degrees, or 70 to 80 degrees. In some embodiments, the angle of the heel support member 450 can be approximately the same as the toe support member 455. In other embodiments, the heel support member 450 can have an angle that is different than the toe support member 455.

The insert 404 is configured to cover the rear opening and cover the toe and heel support members via a heel channel 413 and a toe channel 412. The toe support member 455 and heel support member 450 sit within the channels 413, 412 when the insert 404 is secured to the lap joint. The support members 450, 455 increases the surface area for the insert 404 to adhere to increase bonding and durability.

The toe support member 455 and heel support member 450 divide the rear opening into three sub-openings. The rear opening is divided to have an upper heel opening 410, upper toe opening 408, and a lower central opening 406. In other embodiments, there can be 3 or more support members dividing the rear opening into 4 or more sub-openings. Further, in other embodiments, the support members may extend across the rear opening connecting to either the top rail, heel, inflection seam, or toe portion of the rear opening.

The rear opening comprises a surface area ranging from approximately 750 mm2 to about 1250 mm2. In the illustrated embodiment, the rear opening has a surface area of about 975 mm2. The rear opening surface area can be measured as the combined surface area of all the sub-openings.

In some embodiments the lower rearward region 416 extends further rearwardly (relative to the strike face) than the upper rearward region 418. In general, adding more mass at a lower area of a golf club head 400 body can improve launch characteristics, such as ball speed, forgiveness, and launch angle. By moving the mass lower and away from the center of gravity of the golf club head, the moment of inertia of the club head is improved, which generates more forgiveness on off-center strikes.

Another embodiment of a golf club head 500 having a single support member 550 is illustrated at FIGS. 22-28. The golf club head 500 is similar to golf club heads 300, 400 described above in that the golf club head 500 comprises a support member 550, under cut 502, ballast 514, cascading sole 560, and insert 507. The golf club head 500 is different than the golf club heads 300, 400 in that the ballast 514, undercut 502, support member 550, and insert 507 are sized and positioned in a different manner. The club head 500 of the illustrated embodiment has an insert 507 that covers a majority of the rear while the support member 550 and respective openings 552, 554 are contained in the top half of the club head, above the inflection seam 511. This arrangement of insert 507 and openings 554, 552 increases the lap joint 516 surface area to improve bonding and durability of the insert 507 while providing a more uniform rear surface appearance to achieve a desired aesthetic.

FIG. 22 illustrates a rear perspective view of the golf club head 500 comprising an insert 507, support member 550, and a toe weight 501. The insert 507 extends from the top rail 512 to the sole 510, and from the heel portion to the toe portion to cover a majority of the rear surface. The insert perimeter approximately follows the rear surface perimeter 508. The insert 507 can form at least 80% of the rear surface. For example, in some embodiments, the insert 507 forms at least 85%, at least 90%, or at least 95% of the rear surface area. The insert perimeter can form an area of at least 3.00 in2. For example, the insert perimeter can form an area of at least 3.10 in2, 3.20 in2, 3.30 in2, 3.40 in2, 3.50 in2, 3.60 in2, 3.70 in2, 3.80 in2, 3.90 in2, or at least 4.00 in2.

As illustrated in FIG. 22, the insert 507 further comprises a channel 513 configured to receive, or house, the support member 550. The channel 513 exterior portion is a raised portion relative to the surrounding surfaces on the insert 507 while the interior portion forms a channel which receives the support member 550. The channel 513 comprises complementary geometry to the support member 550.

FIG. 23 illustrates a rear perspective view of the golf club head 500 without the insert 507. As illustrated, the club head comprises a lap joint surface 516 that is recessed relative to the rear exterior surface. The lap joint surface 516 has a bottom portion, an upper perimeter portion, an inflection seam 511, and a support member 550. Together, these portions form an area of at least 1.80 in2. The lap joint surface area can be at least 35% of the insert perimeter surface area. The lap joint surface area increases the bonding area and provides an increased durability and insert retention while simultaneously improving the aesthetics of the club head.

FIG. 23 further illustrates the support member 550 which extends from the top rail 512 downward and towards the toe to the inflection seam 511. The support member 550 selectively reinforces a portion of the perimeter of the club head 500 to improve the vibrational response during impact with a golf ball. The support member 550 divides a rear opening into a heel opening 554 and toe opening 552. The support member 550 can include any of the above features and dimensions as described in the various embodiments above to achieve a desired frequency response.

FIG. 24 illustrates an interior view of the golf club head 500 with the insert 540 attached and the strike face removed. The insert 540 comprises a heel indentation 541 and toe indentation 542 corresponding to the heel opening 554 and toe opening 552, respectively. The heel indentation 541 and toe indentation 542 form the channel 513 for the support member 550 to be received. The channel 513 increases the bonding surface area to improve durability and insert 507 retention.

The golf club head 500 includes internal weighting features to improve performance characteristics. As best shown in FIG. 25, the club head comprises a toe mass pad 530 and a toe undercut 532. The toe mass pad 532 is a buildup of material in the toe portion below the inflection seam 511, thereby to improve MOI and CG properties by placing mass in a low and perimeter portion of the club head 500. The toe undercut 532 is formed in the toe mass pad 530 to create a toe mass overhang 533 suspended over the sole 560. The toe undercut 532 improves mass properties while retaining the spring effect of the strike face.

Contours of the support member 550, undercut 502, cascading sole 560, and ballast 514 are best understood with reference to FIGS. 26-28. FIG. 26 illustrates a cross sectional view at approximately a midplane (in line with the geometric center of the strike face). FIG. 27 illustrates a cross sectional view that is toeward of the midplane and intersecting the support member 550. FIG. 28 illustrates an even more toeward cross section which intersects the toe mass pad 530. Together, FIGS. 26-28 illustrate the progression of the position and sizing of the ballast 514 relative to the strike face and cascading sole 560 in a toeward direction. The ballast 514 increases in height front the midplane to the toe. The increase in height improves the MOI of the club head 500 by placing more mass in the toe. Similarly, the ballast 514 extends more forwardly in the toe than the heel which further increases MOI.

The shapes and contours of the support member 550, undercut 501, cascading sole 560, and ballast 514 improve mass properties, face energy transfer, and vibrational response of the golf club head 500. The ballast 514 and overhang 502 described above improve MOI and CG location. The cascading sole 560 improves face energy transfer and internal stresses. The support member 550 improves vibrational response to provide a desirable sound upon impact. The insert 507 and lap joint surface 516 create an aesthetically pleasing club head which has improved insert retention and durability from the lap joint 516.

ii. Weighted Ballast

A golf club head 600 having a weighted ballast 640 is illustrated in FIGS. 29-33. The weighted ballast 640 includes a ballast weight 628 formed of a material that is denser than the rest of the golf club head 600 to concentrate mass in a low center region to further improve CG position. The golf club head 600 is otherwise similar to the golf club heads 300, 400, 500 in that the club heads comprises a support member 650, undercut 602, cascading sole 660, and ballast. The weighted ballast 640 further improves center of gravity position and moment of inertia by utilizing high density materials in a low and back position of the ballast.

The ballast weight 628 can form a portion of the ballast 640 or can form the entire ballast 640. The ballast weight 628 is separately formed and seated into a recess within the interior cavity such that the ballast weight 628 is exposed into the interior cavity. The ballast weight has corresponding surfaces that abut the surfaces of the recess, outlined in more detail below. The ballast weight 628 has at least one exposed surface. In some embodiments, the ballast weight can have one exposed surface, such as the top surface or the front surface. In other embodiments, the ballast weight can have two or more exposed surfaces. The ballast weight 628 is shaped to follow the contours and transition into surrounding portions of the ballast 640. Similar to the ballasts 314, 414, 514 described above, the ballast 640 can form an undercut via an overhang. In some embodiments, the club head comprises one ballast weight and one corresponding recess. In other embodiments, the club head can comprise two or more ballast weights and two or more corresponding recesses.

The ballast weight 628 and surrounding ballast walls can have an elongated rectangular shape or a rectangular block shape. In other embodiments, the front surface of the ballast weight 628 can be curved such that heel ends and toe ends of the ballast weight 628 are closer to the rear surface of the strike face than the middle. In further embodiments, the top surface of the ballast weight 628 can have a curved surface such that the heel ends and toe ends of the ballast weight 628 extend further from the sole than the middle.

The ballast weight 628 can comprise a mass ranging from 10 grams to 60 grams. For example, in some embodiments, the ballast weight 628 can comprise a mass ranging from 10 to 15 grams, 15 to 25 grams, 25 to 35 grams, 35 to 45 grams, 45 to 55 grams, or 50 to 60 grams. In the embodiments that comprise two or more ballast weights, each ballast weight can have a mass ranging from about 5-30 grams. In some embodiments, the two or more ballast weights can have the same mass. In other embodiments, the two or more ballast weights can have a different mass, where one ballast weight has more mass than at least a second ballast weight.

In a set of irons with varying loft, the mass of the ballast weight can be adjusted according to loft. In some embodiments, as the loft decreases throughout the set, the mass of the ballast weight also decreases. For example, a 4-iron has a ballast weight with a mass that is less than the weighted ballast of a 5-iron. Similarly, the 5-iron has a ballast weight with a mass that is less than the ballast weight of a 6-iron, and so-on on so forth. In other words, in a set of irons, the loft is directly proportional to the mass of the ballast weight. That is, when the loft of the club head increases, the mass of the ballast weight also increases.

As mentioned above, the ballast weight can be separately formed and attached to the ballast via a recess. The ballast weight can be integrally coupled so that it can only be destructively removed, such as attached via welding or adhesives. In other embodiments, the ballast weight can be removably coupled to the recess such as mechanically attached via threaded fasteners. In many embodiments, the ballast weight is exposed to the interior cavity such that the ballast weight cannot be seen from an exterior view of the club head.

In many embodiments, the golf club head comprises a front opening configured to receive a face plate. The front opening allows interior access so that the ballast weight can be positioned in the receiving recess within the interior cavity. Similarly, the rear opening may be sized to also allow access into the interior cavity so that the ballast weight may be positioned within the recess.

The ballast weight can be formed from a first material having a first density while the body of the club head can be formed of a second material having a second density. In many embodiments, the first density is greater than the second density. For example, the ballast weight can be formed from any high-density metallic material such as tungsten, lead, platinum, iridium, rhodium, molybdenum, gold, copper, beryllium, or various steel alloys or combinations thereof. The body material can be formed from various steel alloys, aluminum alloys, or titanium alloys, or any combination thereof.

A club head 600 comprising a ballast weight 620 for improved CG positioning is illustrated in FIGS. 29-33. The golf club head 600 is similar to the golf club heads 300, 400, 500 in that the club head 600 comprises a support member 650, undercut 602, cascading sole 660, and ballast 640. The golf club head 600 is different than golf club heads 300, 400, 500 in that the ballast 640 includes a weighted ballast 628, and the support member 650 and lap joint have altered geometries to decrease stress and improve launch characteristics. The ballast weight 628 comprises a higher density material that forms at least a portion of the ballast 640. The ballast weight 628 lowers CG and increases MOI to increase carry distance, improve spin, and increase forgiveness on off center hits. The ballast weight 628 and support member 650 provide improved mass properties, improved stress, and improved sound response. Together, these features (ballast weight 628, support member 650) create a better launching and sounding iron than a traditional hollow body club head lacking these features.

The club head 600 having a weighted ballast 640 can further comprise a rear opening split by a support member to create a cap-back style iron club head that improves CG and MOI, as illustrated in FIG. 29. The club head comprises similar features to the embodiments described above such as a rear insert 607 having a support member channel 613, a lap joint, and a rear opening which is covered by the insert. The rear opening is defined by the lap joint. The rear opening is split by the support member 650 into a heel opening 654 and a toe opening 650. Together, the support member 650, rear opening, and insert form the cap-back style iron club head that has a lower CG and higher MOI compared to traditional hollow body club heads.

The ballast weight 628 can be shaped and from with different metals to further enhance the mass properties of the club head 600. As illustrated in FIGS. 30 and 32 the ballast weight 628 is formed from a different and heavier material than the rest of the club head body. The higher density and greater weight of the ballast weight 628, compared to steel ballast, enhance spin and launch characteristics by positioning more mass lower in the club and adjusting the center of gravity. The center of gravity location can be adjusted by approximately 0.005 to 0.045 inch lower compared a club head with a ballast that is the same material as the rest of the club head body. In the illustrated embodiment, the club head CG is lower by approximately 0.026 inch. In this embodiment, the ballast weight 628 is a separately formed piece. A recess 630 in the interior cavity receives the ballast weight 628. The ballast weight 628 is then coupled to the body, at the ballast recess, through any well-known joining method such as spot welding, mechanically coupling, or adhesives. In this embodiment, the club head body is cast with a front opening, which is configured to receive a face plate. The ballast weight 628 is placed into the recess 630 before the face plate is welded onto the body so that the front opening provides access to the weighted ballast recess 630. Once the weighted ballast 640 is coupled to the recess in the body, the face plate is welded on to the body to cover the front opening.

The ballast weight can shift its weight by use of recesses to adjust the overall mass properties and center of gravity locations. As illustrated in FIG. 31, the ballast recess 630 comprises a bottom surface 632, a rear surface 634, a toe surface 636, and a heel surface 638. The bottom surface 632 may be flush with the interior surface of the sole or may be raised from the interior surface of the sole. The heel surface 638 and toe surface 636 extend approximately vertical and perpendicular to the strike face. The rear surface 634 extends vertically and approximately perpendicular to the toe and heel surfaces 636, 638. In other embodiments, the recess 630 can comprise other various shapes or sizes as desired to adjust the overall mass properties and center of gravity locations or to improve geometries for casting.

The ballast recess bottom surface 632 is configured to abut the ballast weight bottom surface. The ballast recess rear surface 634 is configured to abut the ballast weight rear surface. The ballast recess toe surface 634 is configured to abut the ballast weight toe surface. The ballast recess heel surface 638 is configured to abut the ballast weight heel surface. The ballast weight top surface forms a smooth continuous surface with the weighted ballast top surface.

In the illustrated embodiment, the ballast weight 628 is located approximately in the center of the cavity. In other embodiments, the ballast weight 628 can be located at the toe end of the cavity, or in the heel end of the cavity. The location of the ballast weight 628 affects the center of gravity and moment of inertia of the club head to achieve a desired shot shape or forgiveness. For example, in one embodiment, the ballast weight 628 can be placed more toeward to either increase the moment of inertia or provide a fade bias. In another embodiment, the ballast weight 628 can be placed more heelward to provide a draw bias.

Multiple ballast weights can be seated in the golf club head. In the illustrated embodiment, the club head has one ballast weight. In other embodiments, the club head can comprise two or more ballast weights. For example, the club head can comprise a toe ballast weight and a heel ballast weight that are separate and distinct. As such, the club head can comprise two or more ballasts recesses configured to receive each of the two or more ballast weights. The heel and toe ballast weights improve the moment of inertia of the club head by removing heavy mass from the center of the club head to the perimeter of the club head. FIGS. 34A-34F illustrates club heads 700a, 700b, 700c, 700d, 700e comprising two or more ballast weights. The club heads 700a, 700b, 700c, 700d, 700e comprise a heel ballast weight 750a, 750b and a toe ballast weight 740a, 740b located at the heel and toe ends of the interior cavity, respectively.

The ballast weight 628 has a top surface 642 and a forward surface 644 which protrudes towards the rear surface of the strike to partially define an undercut to improve mass properties and decrease high stress concentrations, as illustrated in FIGS. 29-33. The ballast weight 628 is proximate to the rear surface of the strike face but does not contact the rear surface of the strike face. The ballast weight 628 forms a portion of the interior surface of the internal cavity. The forward surface 644 partially defines an undercut 602.

As mentioned above, the ballast 640 forms an undercut 602, which overhangs a portion of the sole return. The ballast 640 can form the entire undercut 602 or can form a portion of the undercut 602. The undercut 602 is similar to the undercuts described above and can be adjusted to provide desired mass properties and face flexure characteristics.

The club head 600 further comprises a support member 650. The support member 650 extends across the rear opening and connects to the top rail and to the toe sole portion of the rear wall. In this embodiment, the support member 650 comprises a thickness profile which tapers as it connects to the top rail and sole, as illustrated in FIG. 33. The support member 650 connecting to the lap joint has greater thickness than the lap joint. Reducing the thickness of the lap joint and top rail improves discretionary mass. Furthermore, the support member 650 selectively reinforces the top rail 612 so that the walls of the top rail 612 and lap joint can be made thin while maintaining durability. A thinner top rail 612 improves ball speed by up to 2 mph by allowing for dynamic lofting upon impact with a golf ball.

The support member 650 further comprises an increased width in a heel-toe direction when compared to golf club head 500 with support member 550. The increased width of the support member reduces stresses found in the top rail by selectively reinforcing high stress regions.

The weighted ballast 640 can provide angled contours that correspond to the contours of the rear opening to improve mass properties. The rear opening and lap joint follows the contour of the weighted ballast 640 and ballast weight 628, as illustrated in FIG. 31. The contour of the bottom perimeter of the lap joint extends from the heel towards the toe in a substantially straight or linear manner, above the weighted ballast 640. The contour of the lap joint then angles upwards towards the toe and follow the contour of the weighted ballast 628 and toe mass pad. As such, the bottom perimeter portion is divided into a toe portion and a heel portion wherein the toe portion is angled and is located above the toe weight and the heel portion is less angled than the toe portion and approximately parallel to the weighted ballast top surface 642.

The lap joint bottom perimeter is approximately parallel to the top surface of the ballast 642. As such, the lap joint bottom perimeter is offset by a distance measure from the top surface of the ballast to the lap joint edge, in a top-bottom direction. The offset of the lap joint from the top surface of the ballast can range from 0.020 inch to 0.250 inch. In the illustrated embodiment, the offset is approximately constant along the length of the bottom perimeter lap joint in a heel-toe direction. The constant offset provides a consistent backwall geometry which improves back ball flexure and stress reduction.

The club head can comprise a reduced thickness zone 628 that is an area of decreased thickness on the rear wall that advantageously removes material from the high toe to improve discretionary mass, as best shown in FIG. 31. The reduced thickness zone 628 could also be considered a recess. The mass saved from the reduced thickness zone 628 can be allocated to other regions such as the weighted ballast 640 or to the toe weight 601 mass.

Golf club heads 700a, 700b, 700c, 700d, 700e, 700f comprising two or more ballast weights that further improve MOI are illustrated in FIGS. 34A-34F. In these embodiments, the two or more ballast weight improve MOI of the club head by locating high density material in the toe and heel portions of the weighted ballast. The illustrated club heads 700a, 700b, 700c, 700d, 700e, 700f have substantially similar construction to one another. The difference between the club heads 700a, 700b, 700c, 700d, 700e, 700f is the sizing, locations, and arrangement of the two or more ballast weights within internal cavity.

A club head 700a comprising a toe ballast weight 740a and a heel ballast weight 750a that each have three surfaces exposed to the interior cavity is illustrated in FIG. 34A. In this embodiment, the toe ballast weight 740a and heel ballast weight 750a have a front, rear, and top surface that are exposed to the interior cavity. The toe ballast weight 740a and the heel ballast weight 750a are located on a ledge, rather than a recess.

A club head 700b comprising a toe ballast weight 740b and a heel ballast weight 750b that each have three surfaces exposed to the interior cavity is illustrated in FIG. 34B. The club head 700b is similar to the club head 700a in that the toe and heel ballast weights 740b, 750b sit on a ledge and have a front, rear, and top surface that are exposed to the interior cavity. The club head 700b is different than club head 700a in that the toe ballast weight 740b is larger and has more mass than the toe ballast weight 740a to further increase MOI.

A club head 700c comprising a toe ballast weight 740c and a heel ballast weight 750c that each have only one surface exposed to the interior cavity is illustrated in FIG. 34C. In this embodiment, the toe and heel ballast weight 740c, 750c have only a front surface that is exposed to the interior cavity. As such, the toe ballast weight 740c and heel ballast weight 750c are received by recesses located on the front surface of the ballast, above the undercut. The toe ballast weight 740c and heel ballast weight 750c do not form any portion of the top surface of the weighted ballast. The toe ballast weight 740c and heel ballast weight 750c are entirely separated by a center portion of the weighted ballast.

In other embodiments, the toe weighted ballast 740d and heel weighted ballast 750d can be connected by a slim center bar, as illustrated in FIG. 34D. The club head 700d is similar to the club head 700c in that the toe ballast weight 740d and heel ballast weight 750d are only exposed on the front surface of the weighted ballast. The club head 700d is different than club head 700c in that the toe ballast weight 740d and heel ballast weight 750d are connected by a slim center bar. The slim center bar can be integrally formed with the toe ballast weight 740d and the heel ballast weight 750d to form a single piece ballast weight. In this embodiment, the weighted ballast has a dumbbell shaped appearance with a majority of the mass located in the toe ballast weight 740d and the heel ballast weight 750d to improve the MOI while reducing the amount the parts needed for the final assembled club head.

A club head 700e comprising a toe ballast weight 740e and a heel ballast weight 750e that each have two surfaces exposed to the interior cavity are illustrated in FIG. 34E. The club head 700e is similar to the club head 700c in that the toe ballast weight 740e and heel ballast weight 750e is exposed on a front surface of the ballast. The club head 700e is different than club head 700c in that the toe ballast weight 740e and heel ballast weight 750e are further exposed on a top surface of the ballast. As such, the toe and heel ballast weights 740e, 750e have two surfaces that are exposed to the interior cavity. The toe and heel ballast weights 740e, 750e have a front surface and a top surface that are exposed to the interior cavity to improve manufacturability and ease of placement of the toe and heel ballast weights 740e, 750e into corresponding recesses.

A club head 700f comprising a toe ballast weight 740f and a heel ballast weight 750f that are located more toeward than the toe ballast weight 740e of club head 700e to further improve MOI is illustrated in FIG. 34F. The club head 700f is similar to the club head 700e in that the toe ballast weight 740f and heel ballast weight 750f have two surfaces that are exposed to the interior cavity. The club head 700f is different than club head 700e in that the toe ballast weight 740f is located more toeward than the toe ballast weight 740e of club head 700e to adjust the mass properties and achieve a desired performance benefit such as promoting a draw ball flight.

iii. Insert Retainers

Various golf club heads having insert retainers for improved durability and security of the insert to the club head are illustrated in FIGS. 35-44. The insert retainers help secure and prevent the insert from separating from the body off over pro-longed use and in extreme conditions. In some exemplary embodiments, the club head and/or the insert comprise at least one tab to create an interference fit or press fit between the lap joint and the insert.

In some embodiments, the insert 807 can comprise an external insert retainer, as shown in FIGS. 35-38. The insert retainer is formed by a lap joint tab 814 on the club head body and a seated portion 809 formed on the insert 807. The lap joint tab 814 and insert seated portion 809 comprise complementary geometry such that the insert seated portion 809 receives the lap joint tab 814. The lap joint tab 814 abuts the insert seated portion 809, preventing the insert 807 from being removed and ensuring it remains connected to the lap joint 812.

FIG. 35 illustrates a cross-sectional view of the insert retainer. As shown in the figure, the insert seated portion 809 is in front, or located inwardly, from the lap joint tab 814 to prevent rearward translation of the insert 807. The rear surface of the insert 807 is continuous with the rear surface of the lap joint tab 809 to form a smooth surface. The rear surface of the insert forms a portion of the rear surface of the club head.

FIG. 36 illustrates a rear view of the insert 807 and the seated portion 809. As shown in the figure, the seated portion 809 is located on the top perimeter of the insert and is projects away from the interior surface 808 of the insert 807. When the insert 807 is assembled onto the club head body, the seated portion 809 extends inwardly into a cavity of the body, and the insert seated portion 809 is concealed by the lap joint tab 814.

FIG. 37 illustrates a rear view of the club head 800 and the insert 807. As shown in the figure, the lap joint tab 814 sits within the seated portion 809 of the insert 807. The lap joint tab 814 protrudes downwardly towards the sole from the top perimeter of the rear opening. The lap joint tab 814 creates a discontinuity in the lap joint 812 surface, as illustrated in FIG. 38.

A club head 900 with an insert 907 having an insert retainer that is not visible from an exterior rear view is illustrates in FIGS. 39-41. The insert 907 comprises a tab 909 that hooks around an inner surface of the rear wall of the club head to prevent rearward translation. The tab 909 is configured to be received by a lap joint notch 914, or seated portion. The lap joint notch 914 creates a discontinuity in the lap joint 912, as shown in FIG. 40. In this embodiment, the tab 914 is located in the interior of the club head so that it cannot be seen from the rear of the club head, as shown in FIG. 41, to create a smooth and continuous rear opening perimeter.

A club head 1000 with an insert 1007 having an insert retainer that is formed entirely on the insert is illustrates in FIGS. 42-44. In this embodiment, the insert retainer is formed entirely on the insert such that that lap joint 1012 comprises no complementary geometry or change in geometry. The interior surface of the insert comprises a tab 1009 that forms a groove. The groove is configured to the receive the lap joint 1012 wall to create a tongue-and-groove type mating geometry. One, two, three, or four or more tabs 1009 can be provided around a perimeter of the interior surface to provide a desired retention capability.

As shown in FIG. 43, the club head 1000 comprises a support member 1050 extending across the rear opening. The insert 1007 comprises a first tab located on the toe side of the support member 1050 and a second tab located on the heel side of the support member 1050. The insert tabs 1009 are configured to receive the top perimeter portion of the lap joint 1012. In other embodiments, the insert tabs 1009 can be positioned at other locations on the lap joint 1012, such as the heel portion, toe portion, or bottom portion. Or in other embodiments, the insert tabs 1009 can be sized to receive the support member 1050.

The insert retainers can be used in conjunction with support members, undercuts, and cascading soles as described above to create a club head with increased face flexure and improved stress flow around the strike face while also maintaining sufficient durability of the insert. The club head can be provided with any number of insert retainers at various locations of the insert to further improve insert durability.

iv. Dampers

In some embodiments, the club heads described above may comprise dampers to aid with vibrational and acoustic response, as illustrated in FIGS. 45-48. For example, the club head may comprise tape, adhesives, or other elastomeric filler material deposited on various locations of body. The dampers may be places on the back of the strike face, on the sole, on the top rail, on the support member, on the lap joint, or on the weighted ballast.

A club head 1100 comprising a damper 1110 located on the rear surface of the strike face is illustrated in FIG. 45. The damper 1110 can be used to attenuate club head vibrations at impact, as well as tune feel and sound characteristics. The damper 1110 is preferably made of a soft and lightweight material. In the illustrated embodiment, the damper 1110 comprises a very high bond (“VHB”) tape. In other embodiments, the damper can comprise other polymeric material such as TPE, TPU, or various combinations of different materials. In other embodiments, the damper can comprise a plurality of layers. For example, the damper can comprise an adhesive layer and a polymeric layer.

In many embodiments, the damper comprises a three-layer structure. In these embodiments, the damper comprises an adhesive layer, a stiffening layer opposite the adhesive layer, and a damping layer sandwiched between the adhesive layer and the stiffening layer. The adhesive layer can form a bottom surface of the adhesive strip and serves to adhere the adhesive strip to the strike face rear surface. In such three-layer embodiments, the damping layer can comprise a viscoelastic polymer configured to dissipate vibrations by converting kinetic energy into heat. The damping layer can comprise any viscoelastic polymer or material such as an elastomer, butyl rubber, silicone rubber, a thermoplastic elastomer (TPE), thermoplastic polyurethane (TPE), or other suitable materials with viscoelastic properties.

In many embodiments, the stiffening layer comprises a thin layer of material that comprises a high tensile strength to provide rigidity to the damper without contributing a significant amount of mass to the damper. In many embodiments, the stiffening layer can be formed of a polymeric material, a composite material, or glass cloth. In some embodiments, the stiffening layer can comprise a fiber-reinforced composite such as Glass Fiber Reinforced Polymer (GFRP), Carbon Fiber Reinforced Polymer (CFRP), Aramid Fiber Reinforced Polymer (AFRP), Natural Fiber Reinforced Composites, Basalt Fiber Reinforced Polymer, Wood Fiber Reinforced Composites, Metal Matrix Composites (MMC), and Ceramic Matrix Composites (CMC). In alternative embodiments, the stiffening layer can comprise a lightweight metallic material such as aluminum alloys, titanium alloys, magnesium alloys, beryllium, and lithium-aluminum alloys.

As discussed above, the stiffening layer comprises a high tensile strength that provides rigidity to the adhesive strip. In many embodiments, the tensile strength of the stiffening layer can be greater than about 60 MPa, greater than about 110 MPa, greater than about 180 MPa, greater than about 220 MPa, greater than about 260 MPa, greater than about 280 MPa, or greater than about 290 MPa. In some embodiments, suitable composite materials may have a tensile strength at yield of from about 60 MPa to about 350 MPa.

The damper comprises a thickness between 0.01 mm and 0.49 mm. For example, the adhesive strip comprises a thickness between 0.01 mm to 0.05 mm, 0.06 mm to 0.10 mm, 0.11 mm to 0.15 mm, 0.16 mm to 0.20 mm, 0.21 mm to 0.25 mm, 0.26 mm to 0.30 mm, 0.31 mm to 0.35 mm, 0.36 mm to 0.40 mm, 0.41 mm to 0.45 mm, or between 0.46 mm to 0.49 mm. In other embodiments, the thickness can be between 0.01 mm to 0.10 mm, 0.05 mm to 0.15 mm, 0.10 mm to 0.20 mm, 0.15 mm to 0.25 mm, 0.20 mm to 0.30 mm, 0.25 mm to 0.35 mm, 0.30 mm to 0.40 mm, 0.35 mm to 0.45 mm, 0.40 mm to 0.49 mm, or between 0.45 mm to 0.49 mm. In some embodiments, the thickness can be 0.01 mm, 0.03 mm, 0.05 mm, 0.08 mm, 0.10 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.20 mm, 0.23 mm, 0.25 mm, 0.30 mm, 0.35 mm, 0.40 mm, or 0.45 mm.

In other embodiments, the cavity can be filled by a filler material to further aid in damping vibrations. The filler material may be injected in liquid form into the cavity prior to the securing of the insert to the body. The filler material, once in the cavity, may then cure and solidify. The filler material may partially fill the cavity. The filler material may be placed on the rear surface of the strike face, in the bottom of the cavity, and/or in the top of the cavity. The filler material may connect to the rear surface of the strike face and the inner surface of the rear wall. In other embodiments, the filler material may only touch the rear surface of the strike face.

The filler material can fill between 1% and 99% of the cavity. For examples, filler material can fill a percent of the interior cavity ranging from 1% to 5%, from 5% to 9%, from 9% to 13%, from 13% to 17%, from 17% to 21%, from 21% to 25%, from 25% to 29%, from 29% to 33%, from 33% to 37%, from 37% to 41%, from 41% to 45%, from 45% to 49%, from 49% to 53%, from 53% to 57%, from 57% to 61%, from 61% to 65%, from 65% to 69%, from 69% to 73%, from 73% to 77%, or from 77% to 99%. The filler material can fill less than 99%, less than 89%, less than 79%, less than 69%, less than 59%, less than 49%, less than 39%, less than 29%, less than 19%, or less than 9% of the volume of the interior cavity.

In some embodiments, and as illustrated in FIGS. 46-48, the golf club head 1200 can further comprise a damper 1210 disposed within the hollow cavity. The damper 1210 reduces vibrations to improve the sound and feel of the club head, without contributing a significant amount of mass to the club head. Compared to existing club heads without an insert, the herein described insert and club head can achieve optimal sound and feel, while also improving performance characteristics, particularly forgiveness and launch. The damper 1210 can comprise an outer surface, an inner surface, and a slit 1213 disposed between the inner and outer surface. In some embodiments, the slit 1213 can continue through the entire length of the damper 1210 creating a hollow channel. The inner surface of the damper contacts the rear surface of the strike face. In some embodiments, the outer surface of the damper contacts at least a portion of the rear wall inner surface or the ballast 1214. In other embodiments, the outer surface of the damper does not contact any portion of the rear wall inner surface. Furthermore, the damper 1210 can comprise at least one locating feature 1212 disposed along the inner and/or outer surfaces. The locating feature 1212 ensures that the damper 1210 is properly positioned within the club head and remains stationary. In other embodiments, the CTP can be coupled to the body via epoxy adhesion, tape, or a snap-lock mechanical design. Furthermore, the locating feature 1212 can ensure that the damper rests at an optimized location within the club head relative to the sweet spot. In some embodiments, the locating feature 1212 is a protrusion. While in other embodiments, the locating feature is a recess. The inclusion of a damper 1210 allows the incorporation of more complex club head geometries/materials to control the sound, feel, and COR.

In some embodiments, the dampening elements 1110, 1210 can be used in combination with each other. In an exemplary embodiment, the dampening element 1110 can occupy an upper portion of the rear surface of the strike face, while the dampening element 1210 can occupy a lower or central portion of the rear surface of the strike face. The dampening element 1210 can abut an overhang portion of the ballast and a rear surface of the strike face to improve vibrational response.

Like the insert, the damper can be formed from a polymer or flexible material with a low shore durometer (i.e., soft material). The damper can be formed from a polymer matrix. The polymeric matrix can comprise glass-filled elastomer, a stainless steel-filled elastomer, a tungsten-filled elastomer, a thermoplastic polyurethane (TPU) composite, a thermoplastic elastomer (TPE) composite, or any other elastomer matrix composite, a Kevlar® (aramid) fiber-reinforced polymer, a carbon-fiber reinforced polymer, rubber, ethylene-vinyl acetate foam, polymer-based foam, any combination of a suitable resin and a suitable reinforcing fiber, or any combination of the above materials. Soft or flexible materials improve the feel and sound of the golf club head through impact.

EXAMPLES Example 1: Study of Undercut in Hollow Body Iron

As described in detail above, the ballast and undercut can be applied to a golf club head alone and in conjunction with other features, such as a cascading sole, to improve club performance. In the example below, performance improvements generated by the undercut 102 were studied by comparing a golf club head without an undercut (golf club A, hereafter “Club A”), a golf club head with an undercut (golf club B, hereafter “Club B”), a golf club head without an undercut and with a cascading sole (golf club C, hereafter “Club C”), and a golf club head with an undercut and with a cascading sole (golf club D, hereafter “Club D”). Performance improvements were measured and analyzed using finite element analysis (FEA). Specifically, FEA was used to measure peak stress values within the forward region. Average peak stress, along with a measured surface area experiencing peak stress, were used to determine the potential for each club to efficiently transfer impact energy back to the ball. Reductions in average peak stress serve as an indicator for improved durability and potential performance enhancement via face thinning and sole thinning.

Each of the example Clubs A, B, C, and D were substantially similar having the same overall mass, material construction, and loft angle. Impact loading in each club was simulated at 105 mph. The example clubs each comprise unique internal cavity configurations, described above. Average peak stress between the strikeface and ballast, within the forward region of the sole, was calculated for each example. Likewise, an area of average peak stress was calculated for each example. Finally, average peak stress within the strikeface was calculated for each example. Table 1 below, shows the peak face stress, peak stress of the forward sole region, and the peak stress area within the forward region of the sole, for each of the example clubs discussed below. Stress values were used to determine the undercut's effect on club performance through face and sole thinning. Example Club A was compared to Club B. Example Club C was compared to Club D. The control club head was similar to the example club heads, but devoid of any stress relieving features.

TABLE 1 Peak Face Stress Peak Forward Sole Stress Club A 218469 psi 158169 psi Example 1 217117 psi 156858 psi Example 2 213311 psi 155419 psi Example 3 209851 psi 154689 psi

Club A

Club A was representative of a prior art golf club head lacking all stress relieving features and was similar to FIG. 8. As the representative of a traditional hollow body golf club head, Club A comprised a ballast without an undercut and without a cascading sole. Without an undercut, the forward region of the sole and the ballast met at a substantially right angle. Likewise, without the cascading sole, the strikeface transitioned smoothly to the forward region of the sole.

As shown in Table 1, FEA analysis was used to calculate a value for peak stress within the strikeface of the Club A. Under a 105 mph impact load, the peak stress of the strikeface was 218469 psi. Under the same impact load, the forward region of the strikeface had a peak stress of 157440 psi.

Club B

Club B was representative of a hollow body golf club head with an undercut stress relieving feature. Hollow body Club B was similar to Club A, but Club B included an undercut as stress relieving feature. Rather than meeting at a right angle, the undercut allowed the forward region of the sole to extend beneath the ballast. The undercut of Example 1 comprised a depth of 0.065 inch, a height of 0.083 inch, an undercut transition height of 0.185 inches, and 1.16 inches.

The values for peak face stress, peak forward sole stress, and peak stress area were determined with FEA analysis and simulated impact with a golf ball at 105 mph. The peak face stress was 217117 psi and the peak forward sole stress 156257 psi. When compared to the Club A, the undercut reduced peak stress within the strikeface by 1352 psi and reduced peak stress within the forward region of the sole by 1183 psi. This club showed that the ballast and undercut allow the both the strikeface and forward region of the sole to store more strain energy. This means that Club B showed improved durability and improved spring response to impact loading.

Club C

The hollow body Club C was representative of a club head comprising a forward region of the sole with a cascade, only. Club C was similar to Club A and B, but comprised a cascading sole as a singular form of stress relief. The transition from face to sole comprised first tier, a second tier and a tier transition between the first tier and the second tier. The first tier had a first tier thickness and second tier thickness, less than the first tier thickness. The tier transition was sloped to gradually transition the first tier thickness to the second tier thickness. The example did not comprise an undercut and the forward region of the sole and ballast met at a substantially right angle.

Referring again to Table 1, the Example 2 hollow body golf club head had a peak face stress of 213311 psi, or a 5158 psi reduction of peak stress within the strikeface. The Example 2 club had a peak forward sole stress of 154742 psi (pounds per square inch), or a reduction in peak forward sole stress of 2698 psi This example showed that cascading sole reduced stress through increased storage of strain energy for improved durability and spring response under impact loading.

Club D

Club D was representative of a club head comprising an undercut and a cascading sole as two forms of stress relief for the strikeface and forward sole region. The ballast comprised an undercut, which effectively lengthened the forward sole region beneath the ballast. The cascading sole comprised a first tier, a second tier, and a tier transition between the first and second tiers. The first tier comprised a first tier thickness and the second tier comprised a second tier thickness, less than the first tier thickness. The tier transition was sloped to gradually transition the first tier thickness to the second tier thickness.

Club D was also subjected to FEA analysis under simulated ball impact at 105 mph. The peak face stress was 209851 psi, for a reduction of peak stress in the strikeface of 8618 psi. In other words, the Club D had a 4% reduction in peak stress within the strikeface. The peak stress of the forward sole region was 154689 psi. The forward sole region had a peak stress reduction of 3480 psi, or a 2.2% reduction from the Club A. This example showed that the undercut and cascading sole worked together to reduce peak stresses. Further, this example indicated that the forward region of the sole could tolerate additional loading without reaching fatigue failure. The example showed that ball speed could be improved by thinning the face and sole to match the loading capacity of the forward sole region.

The peak stresses of the forward sole region in each of the club heads, specifically, indicated the potential for adjusting sole and face thickness and the resulting changes to ball speed. The peak stress of the forward sole region was compared to the critical K yield stress value of the forward sole region. Stresses that indicated that the strikeface and sole must be thickened, signaled that the internal cavity configuration would have reduced ball speed. Stresses that indicated that the strikeface and sole could be thinned, signaled that the internal cavity configuration would have increased ball speed.

Club A and Club B were compared to each other relative to a critical K value of 156 ksi. The peak stress of Club A, without an undercut, was 158169 psi. This peak stress value suggested that the sole and face would have needed to be thickened by roughly 2.5% in order to achieve stress values that did not exceed 156 ksi. The thickened face and sole indicated that the internal cavity configuration that would degrade ball speed. Club B, which comprised an undercut, improved peak stress within the forward sole region. Club B had a peak stress of 156868 psi. The lower peak stress of Club B indicated Club B required the sole and face to be thickened less than the sole and face of Club A. These results showed that, after modifications, Club B and the undercut indicated better ball speed over Club A, without an undercut.

Similarly, Club C and Club D were compared to each other relative to the same critical K value of 156 ksi. The peak stress of Club C, with a cascading sole and without an undercut, was 155416 psi. Club C, with peak stress slightly less than the critical K stress, indicated that no modifications for improving or degrading ball speed would have been necessary. The slightly lower peak stress did indicate that the cascading sole in Club C would have increased durability. Club D comprised an undercut in addition to the cascading sole and had a peak stress of 154689 psi. Club D showed that the undercut provided further reduction to peak stress. This reduction in stress indicated that Club D had a face and sole that could tolerate thinning in order to improve ball speed.

The comparison of Club A and Club B and the comparison of Club C and Club D showed that the undercut reduced peak stress within the forward region of the sole. These results further showed that the undercut could be applied to hollow body golf club heads to improve ball speed by leveraging stress reduction to thin the face and sole.

Example 2: Club Performance with Undercut

In a second example, player testing of physical clubs was used to study the performance benefits of the undercut. In this example, a 7 iron comprising an undercut was compared to a structurally similar 7 iron, which lacked an undercut. The sole and face of the 7 iron having the undercut were optimized and reduced in thickness. Over 700 shots were taken on each golf club to analyze ball speed, launch angle, and spin rate.

FIG. 9 compared the average ball speed of the 7 iron having an undercut and the 7 iron without an undercut. The average ball speed of the iron with the undercut was 119.7 mph. The average ball speed of the iron without the undercut was 118.7 mph. FIG. 10 compared the average vertical launch angle of the 7 iron with an undercut and the 7 iron without the undercut. The data showed that the 7 iron with the undercut and the 7 iron without the undercut had substantially similar launch angles. FIG. 11 compared the average spin rate of the same 7 iron with an undercut and 7 iron without an undercut. The 7 iron without an undercut had an average spin rate of 6079.9 rpm. The 7 iron without an undercut had a reduction in average spin with 5990.6 rpm.

Finally, the stat area (data not shown) of the 7 iron with the undercut was compared to the 7 iron without the undercut. The stat area data was used to determine the consistency of each of the golf club heads by plotting shot distance according to the left-right deviation from a straight shot. The 7 iron without the undercut had a distance deviation of 20 m, while the 7 iron with the undercut had a distance deviation of 14 m. The data showed that the undercut 7 iron produced shots that with more consistent distance.

The player results of Example 2 highlighted the performance benefits of the undercut. Specifically, the data showed that the undercut reduced spin on low lofted golf club heads, such as a 7 iron, and improved ball speed for improved distance. Reduced spin on low lofted golf clubs was preferred due to the distance requirements and expectations of longer, low lofted golf clubs. The Example also highlighted a tighter stat area for irons with an undercut and showed that the undercut irons performed more consistently for distance.

Example 3: Club Performance with Undercut and Cascading Sole Region

In a third example, automated testing of physical clubs using a golf swing apparatus was used to study the increased performance of an exemplary club head comprising an undercut in conjunction with a cascading region within the forward sole region. The ball speed the exemplary club head was compared to the ball speed of a structurally similar control club head, which lacked an undercut. The exemplary club head was similar to club head 300 described above and comprised an undercut formed by the angled forward surface of a ballast. The exemplary club head further comprised a cascading region with a profile similar to cascading region 262, wherein the cascading region depth was greater near the center of the club head than near the heel and toe. The control club head was devoid of an undercut and comprised a ballast that met the sole at a substantially right angle. The control club head further comprised a cascading region with a rectangular profile, wherein the cascading region depth was constant in a heel to toe direction.

The inclusion of the angled ballast in the exemplary club head led to a reduction in CG height (measured vertically from the ground plane). The exemplary club head comprised a CG height of 0.580 inch and the control club head comprised a CG height of 0.654 inch. The control club head exhibited a reduction in CG height of 0.074 inch.

Table 2 below compares the average ball speed of exemplary club head in comparison to the average ball speed of the control club head. The ball speed of each club was measured both on center hits and low-center hits (i.e. strikes occurring 0.25 inches below center).

TABLE 2 Ball Speed (mph) Club Head Control Exemplary Increase Center Hit 139.1 140.1 1.0 Low Center 134.3 137.8 3.5

Referring to Table 2, the exemplary club head exhibited significant ball speed gains over the control club head for both center hits and low-center hits. In particular, the exemplary club head exhibited a 1.0 mph increase over the control club head on center hits and a 3.5 mph increase over the control club head on low-center hits. The angled ballast, undercut, and variable depth cascading region resulted in significant improvements in ball speed, particularly on low-center shots, which is a common mis-hit for an iron-type club head.

In general, lowering the CG in an iron-type club head results in an increase in ball speed. The lowering of the CG height in the exemplary club head achieved by the inclusion of the angled ballast provided a significant contribution to the increase in ball speed of the exemplary club over the control club.

The variable depth cascading region of the exemplary club head further contributed to the increase in ball speed over the control club head comprising a rectangular cascading region. The variable depth cascading region effectively lengthened the uniform inner region of the exemplary forward sole region near the heel and toe. Therefore, the proportion of the forward sole region made up by the uniform inner region was greater in the exemplary club head, and the proportion of the forward sole region made up by the cascading region was greater in the control club. Because the uniform inner region comprises a lesser thickness than the cascading region, the forward sole region of the exemplary club head was able to store more spring energy. The increase in spring energy of the exemplary forward sole region is especially significant in the drastic increase in ball speed measured on low-center hits.

The undercut of the exemplary club head allows for a further potential increase in ball speed by effectively lengthening the forward sole region. Effectively lengthening the forward sole region reduces peak stress within the forward sole region. Although the sole and strikeface thicknesses of the exemplary club head and the control club head were the same, the extra stress relief achieved by effectively lengthening the forward sole region would allow for the sole and/or strikeface to be thinned without sacrificing the durability of the forward sole region. Such thinning would allow the exemplary club head to store more spring energy and achieve even greater ball speeds.

Example 4: Wet and Dry Conditions Performance with Undercut

In a fourth example, player testing of physical clubs was used to study the performance benefits of the undercut in varying turf conditions. In this example, a pitching wedge comprising an undercut was compared to a structurally similar pitching wedge, which lacked an undercut. Each golf club was hit in wet conditions and dry conditions and values for average launch angle, spin rate, and ball speed were measured.

FIG. 12 compared the launch angle of a wedge with an undercut and a wedge without an undercut in both wet conditions and dry conditions. The wedge with an undercut had an average launch angle of 24.0 degrees in dry conditions and an average launch angle of 24.5 degrees in wet conditions. The wedge without an undercut had an average launch angle of 23.6 degrees in dry conditions and an average launch angle of 25.1 degrees in wet conditions. Therefore, launch angle in wedges with an undercut and without an undercut was comparable under wet conditions.

FIG. 13 compared the spin rate of the same wedge with an undercut and wedge without an undercut in both wet and dry conditions. The wedge with an undercut had an average spin rate of 8617 rpm (revolutions per minute) in dry conditions and an average spin rate of 8031 rpm in wet conditions. The wedge without an undercut had an average spin rate of 8310 rpm and a spin rate of 7144 rpm in wet conditions. Therefore, the wedge with the undercut had increased spin rates to indicate better turf interaction in both wet and dry conditions for the undercut wedge.

FIG. 14 compared the ball speed of the wedge with the undercut and the wedge without the undercut. The wedge with the undercut had an average ball speed of 97.3 mph (mile per hour) in dry conditions and an average ball speed of 96.9 mph in wet conditions. The wedge without the undercut had an average ball speed of 97.4 mph in dry conditions and an average ball speed of 96.9 mph in wet conditions. The ball speed for the wedge with the undercut and wedge without the undercut were comparable in both wet and dry conditions.

The data above showed that the pitching wedge with the undercut performed more consistently in variable turf conditions than the wedge without an undercut. The launch angle of the wedge with the undercut varied by 0.5 degrees between wet and dry conditions, while the wedge without the undercut had a launch angle that 1.5 degrees. The data showed that the launch angle of the wedge without the undercut varied three times as much as the wedge with the undercut. Similarly, the spin rate of the ball coming off the wedge with the undercut was more consistent than the spin rate of the wedge without the undercut. The spin rate varied by just 586 rpm between dry and wet conditions for the wedge with the undercut, while the spin rate varied by 1166 rpm between dry and wet conditions for the wedge without the undercut. Consistent spin rates for wet and dry conditions of the undercut wedge were preferred, as the purpose of wedge-type golf clubs is consistent ball delivery on the green regardless of weather conditions. The ball speed of the wedge with and without the undercut were substantially similar.

Example 5: Performance Comparison Between Club Heads with and without Support Members

This example demonstrates the value of a support member in view of golf club heads comprising a rea opening, as described above. The stat area of a plurality of club heads according to the present invention (here after “the first exemplary club head”) were compared to a first control club head. The first exemplary club head was similar to club head 300 described above and included a rear opening to an internal cavity, a support member spanning the rear opening, and an internal undercut feature. The first control club heads comprised a construction similar to the first exemplary club head, but without the support member. Similar to the first exemplary club head, the first control club head also included a rear opening to an internal cavity and an internal undercut.

A player performance test was conducted to capture club head performance data under regular conditions of the clubs described above. The blind test consisted of 20 golfers hitting a 10 shots with a 4-iron club head of the first exemplary and control club heads. The test specifically examined the precision and accuracy of each club head by measuring and recording the dispersion area of the finishing positions of each shot for each club head's sample set. A smaller dispersion area represents a more precise club head. The results of the first player performance test are presented in Table 3 below.

TABLE 3 Average Average Dispersion Dispersion Area Percentage Average Difference Decrease Dispersion Over Over Area (yd2) Control (yd2) Control 4-iron Exemplary 2149.1 1005.4 31.9% Control 3154.5 N/A N/A

The first exemplary club head exhibited a significant decrease in dispersion area relative to the first control club head. The dispersion area of the first exemplary club head was 31.9% less than the first control club head. The results of the player performance test illustrate the improved performance of the first exemplary club heads over the first control club heads. The first exemplary club head was significantly more precise than the first control club head. This increased precision can be attributed to the normalization of club head deformation upon impact due to the inclusion of the support member. Particularly, the support member stabilizes strike face deflection and eliminates the likelihood for “jumpers” or “fliers” where a golf ball travels anomalously further than intended.

Jumpers can generally be defined by a large carry distance dispersion interval. FIG. 49, illustrates a significant decrease in carry distance dispersion. As illustrated in FIG. 49, the isolated average dispersion in carry distance is roughly 52 yards for the first exemplary club head and roughly 66 yards for the first control club head. As such, there is a significant decrease (21% decrease) in average carry distance between the first exemplary club head and the first control club head.

Example 6: Mass Properties and Performance Comparison Between Club Heads with and without Interior Mass Features

This example provides a demonstration of the value of a ballast weight in view of golf club heads comprising an internal undercut, described above. As such, the mass distribution properties of a plurality of club heads according to a second exemplary club head and a second control club head. The second exemplary club head was similar to club head 600 described above and included an insert covering a rear opening to an interior cavity and a ballast weight forming an undercut via an overhang. The ballast weight further included a mass seated into a recess within the interior cavity. The second exemplary club head was similar to Example above, and also comprised a support member spanning the rear opening.

The second control club head comprised a similar internal cavity and undercut compared to the second exemplary club head. However, the second control club head did not include a ballast weight with a mass seated into a recess. Further, the second control club head did not include a support member spanning a rear opening.

As illustrated in Table 4 below, the ballast weight feature of the second exemplary club head exhibited a slight improvement in CG. The second exemplary club head comprised a slightly lower CG location (represented by a lower CGy metric) than the second control club head. As discussed above, the second exemplary club head utilizes a ballast weight comprising a mass located within a recess in the interior cavity. This ballast weight pushed the club head CG 25 hundredths of an inch closer to the ground plane relative to the second control club head. Furthermore, the ballast weight feature of the second exemplary club head exhibited a negligible decrease in MOIyy. This change could be attributed to inadvertent mass distributions in a toe-to-heel or front-to-back direction due to the inclusion of the ballast weight feature.

TABLE 4 CG Delta % Height MOIyy CGy Delta Model (in.) [g-in2] (in.) MOIyy I530 (Second Control Club 0.525 402 — — Head) Violet Tungsten (Second  .499 401 −0.026 0% Exemplary Club Head)

A second player test was conducted to capture club head performance data between the second exemplary club head and the second control club head under regular conditions. The test consisted of 15 golfers hitting 10 shots with each 7-iron iteration of the second control and exemplary club heads. The test specifically examined ball speed, launch angle, spin rate, and carry distance. The ball flight characteristics of each club are presented in Table 5 below.

TABLE 5 Launch Carry Ball Speed Angle Spin Rate Distance (mph) (degrees) (rpm) (yd) 7-iron Second 123.8 14.2 5184 180.1 Control Club Head Second 124.4 14.9 5286 181.4 Exemplary Club Head

The second exemplary club heads performed similarly to the secondary control club heads with respect to each ball flight characteristic (i.e., ball speed, launch angle, spin rate, and carry distance). With respect to the 7-iron, the second exemplary club head exhibited a 0.6 mph increase (0.48% increase in ball speed), a 0.7-degree increase (4.9% increase) in launch angle, a 102-rpm increase (1.9% increase) in spin rate, and a 1.3-yard increase (0.7% increase) in carry distance. In general, the ball flight characteristics of Table 5 show noticeable improvements from the secondary control club head to the second exemplary club head. Specifically, the increase in launch angle of the second exemplary club head over the secondary control club head resulted in an increase in carry distance, and the substantial increase in spin rate improves stopping power.

The second exemplary club heads comprised improved ball flight characteristics to the secondary control club heads. The improved ball flight characteristics can be attributed to the inclusion of the ballast weight, relative to the control club head. The ballast weight, and the associated mass element seated within a recess in the interior cavity, lowered overall clubhead CG, as illustrated in Table 4, resulting in better ball speed and a higher launch angle.

Clause 1: A golf club head, comprising: a hollow body defining an enclosed internal cavity, the hollow body comprising: a front, a heel, a toe opposite the heel, a sole, a top rail, a rear extending between the top rail and the sole, and separated from the strike face by the internal cavity; a front perimeter edge defining a front opening configured to receive a strike face insert; a lap joint edge extending around a perimeter of the rear defining a rear opening; a ballast located in the interior cavity at the junction of the sole and the rear and extending in a heel-toe direction, wherein the ballast comprises a bottom surface, rear surface, toe surface, and heel surface defining a ballast recess/receptacle configured to receive a ballast weight, wherein the ballast weight is seated within the recess/receptacle to form a continuous/smooth ballast wall and is exposed to the interior cavity.

Clause 2: A golf club head, comprising: a strike face; a body coupled to the strike face to define an internal cavity, the body comprising: a front having a front perimeter configured to receive the strike face; a heel, a toe opposite the heel, a sole, a top rail opposite the sole, a rear opposite the front and extending between the top rail and the sole, the rear defining a rear opening and a lap joint bordering the rear opening; a ballast located in the interior cavity at the junction of the sole and the rear extending in a heel-toe direction, wherein the ballast comprises a ballast bottom surface, a ballast rear surface, a ballast toe surface, and a ballast heel surface, wherein the ballast defines a ballast recess; and a ballast weight disposed in the ballast recess, wherein the ballast weight is formed of a ballast weight material that is more dense than a remainder of the body, wherein the ballast weight comprises a ballast weight bottom surface configured to abut the ballast bottom surface, a ballast weight rear surface configured to abut the ballast rear surface, a ballast weight toe surface configured to abut the ballast toe surface, and a ballast weight heel surface configured to abut the ballast heel surface.

Clause 3: A golf club head, comprising: a hollow body defining an enclosed internal cavity, the hollow body comprising: a front portion, a heel portion, a toe portion opposite the heel portion, a sole, a top rail, a rear extending between the top rail and the sole, and separated from the strike face by the internal cavity; a front perimeter edge defining a front opening configured to receive a strike face insert; a lap joint edge extending around a perimeter of the rear defining a rear opening; a weighted ballast located in the interior cavity at the junction of the sole and the rear and extending in a heel-toe direction, wherein the weighted ballast comprises a heel recess and a toe recess configured to receive a heel ballast weight and a toe ballast weight, respectively; wherein the toe ballast weight comprises a toe top surface and a toe front surface that are exposed to the interior cavity; wherein the heel ballast weight comprises a heel top surface and a heel front surface that are exposed to the interior cavity.

Clause 4: The golf club head of Clause 1, wherein the ballast weight comprises a front surface that is contoured towards the rearward region to define an undercut.

Clause 5: The golf club head of Clause 1, wherein the ballast weight is formed of a tungsten material.

Clause 6: The golf club head of Clause 1, wherein the ballast weight comprises a mass between 5 and 60 grams.

Clause 7: The golf club head of Clause 4, wherein the ballast weight comprises a mass between 13 and 35 grams.

Clause 8: The golf club head of Clause 1, wherein the ballast weight has a top surface that is curved such that a heel end and a toe end of the ballast weight extend further from the sole than a middle of the ballast weight.

Clause 9: The golf club head of Clause 1, wherein the ballast weight is welded to the weighted ballast.

Clause 10: The golf club head of Clause 1, wherein the hollow body comprises a first material with a first density and the ballast weight comprises a second material with a second density, wherein the second density is greater than the first density.

Clause 11: The golf club head of Clause 1, further comprising a support member extending across the rear opening, wherein the support member connects at least two portions of the lap joint edge.

Clause 12: The golf club head of Clause 2, wherein the golf club head comprises an insert comprising a channel, wherein the insert is configured to cover the rear opening such that the channel receives the support member.

Clause 13: The golf club head of Clause 2, wherein the support member extends from a top rail portion of the lap joint to a toe portion of the lap joint.

Clause 14: The golf club head of Clause 2, wherein the support member comprises a variable thickness along a length of the support member.

Clause 15: The golf club head of Clause 1, wherein the weighted ballast bottom surface is contoured towards the rear to define an undercut.

Clause 16: The golf club head of Clause 6, wherein the undercut comprises an undercut volume between 0.018 and 0.050 inch.

Clause 17: The golf club head of Clause 6, wherein the undercut comprises an undercut height between 0.070 and 0.090 inch.

Clause 18: The golf club head of Clause 6, wherein the undercut further comprises a ratio of undercut face depth to CG depth, wherein said ratio is 3.0 to 5.5.

Clause 19: The golf club head of Clause 6, wherein the undercut further comprises a cascading region defining an internal transition region from the strike face to the sole.

Clause 20: The golf club head of Clause 1, further comprising: a cascading region defining an internal transition region from the strike face to the sole, the cascading region comprising: a first tier comprising a first thickness; a second tier comprising a second thickness different than the first thickness; and a tier transition region between the first tier and the second tier.

Clause 21: The golf club head of Clause 11, further comprising a cascading region perimeter defining a boundary between the cascading region and the sole; and wherein the cascading region perimeter comprises a cascade front edge proximate a leading edge of the strike face and a cascade rear edge spaced rearwardly from the strike face.

Clause 22: The golf club head of Clause 11, wherein the cascade rear edge is arcuate and bows rearward relative to the cascade front edge; wherein the cascading region comprises a depth measured as a front-to-rear distance between the cascade front edge and the cascade rear edge; and wherein the depth of the cascading region is greater proximate a center of the club head than the depth of the cascading region near the toe portion and the heel portion.

Clause 23: The golf club head of Clause 11, wherein a width of the cascading region is greater proximate the cascade front edge than near the cascade rear edge.

Clause 24: The golf club head of Clause 1, wherein a front-rear CG depth is between 0.080 to 0.110 inch.

Clause 25: The golf club head of Clause 1, further comprising a top rail-to-sole moment of inertia ranging from 95 g·in2 to 130 g·in2 and a heel-to-toe moment of inertia ranging from 350 g·in2 to 420 g·in2.

Clause 26: The golf club head of Clause 1, wherein a geometric center region of the golf club head comprises a thickness of 0.080 inches to 0.150 inches.

Clause 27: The golf club head of Clause 1, further comprising an inflection seam extending across the rear of the club head in a heel-toe direction and dividing the rear into an upper rearward region and a lower rearward region.

Clause 28: The golf club head of Clause 1, further comprising a reduced thickness zone located in an upper toe portion of the interior cavity on a rear wall.

As the rules to golf may change from time to time (e.g., new regulations may be adopted or old rules may be eliminated or modified by golf standard organizations and/or governing bodies), golf equipment related to the methods, apparatus, and/or articles of manufacture described herein may be conforming or non-conforming to the rules of golf at any particular time. Accordingly, golf equipment related to the methods, apparatus, and/or articles of manufacture described herein may be advertised, offered for sale, and/or sold as conforming or non-conforming golf equipment. The methods, apparatus, and/or articles of manufacture described herein are not limited in this regard.

Although a particular order of actions is described above, these actions may be performed in other temporal sequences. For example, two or more actions described above may be performed sequentially, concurrently, or simultaneously. Alternatively, two or more actions may be performed in reversed order. Further, one or more actions described above may not be performed at all. The apparatus, methods, and articles of manufacture described herein are not limited in this regard.

While the invention has been described in connection with various aspects, it will be understood that the invention is capable of further modifications. This application is intended to cover any variations, uses or adaptation of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within the known and customary practice within the art to which the invention pertains.

Claims

1. A golf club head, comprising:

a hollow body defining an enclosed internal cavity, the hollow body comprising:
a front, a heel, a toe opposite the heel, a sole, a top rail, a rear extending between the top rail and the sole, and separated from the strike face by the internal cavity;
a front perimeter edge defining a front opening configured to receive a strike face insert;
a lap joint edge extending around a perimeter of the rear defining a rear opening;
a ballast located in the interior cavity at the junction of the sole and the rear and extending in a heel toe direction, wherein the ballast comprises a bottom surface, rear surface, toe surface, and heel surface defining a ballast recess configured to receive a ballast weight, wherein the ballast weight is seated within the recess to form a continuous and uninterrupted ballast wall and is exposed to the interior cavity.

2. The golf club head of claim 1, wherein the ballast weight comprises a front surface that is contoured towards the towards the rearward region to define an undercut.

3. The golf club head of claim 1, wherein the ballast weight is formed of a tungsten material.

4. The golf club head of claim 3, wherein the ballast weight comprises a mass between 5 and 60 grams.

5. The golf club head of claim 4, wherein the ballast weight comprises a mass between 13 and 35 grams.

6. The golf club head of claim 2, wherein the ballast weight has a top surface that is curved such that a heel end and a toe end of the ballast weight extend further from the sole than a middle of the ballast weight.

7. The golf club head of claim 1, wherein the ballast weight is welded to the weighted ballast.

8. The golf club head of claim 1, wherein the hollow body comprises a first material with a first density and the ballast weight comprises a second material with a second density, wherein the second density is greater than the first density.

9. The golf club head of claim 1, further comprising a support member extending across the rear opening, wherein the support member connects at least two portions of the lap joint edge.

10. The golf club head of claim 9, wherein the golf club head comprises an insert comprising a channel, wherein the insert is configured to cover the rear opening such that the channel receives the support member.

11. A golf club head comprising:

a hollow body defining an enclosed internal cavity, the hollow body comprising:
a front portion, a heel portion, a toe portion opposite the heel portion, a sole, a top rail, a rear extending between the top rail and the sole, and separated from the strike face by the internal cavity;
a front perimeter edge defining a front opening configured to receive a strike face insert;
a lap joint edge extending around a perimeter of the rear defining a rear opening;
a weighted ballast located in the interior cavity at the junction of the sole and the rear and extending in a heel toe direction, wherein the weighted ballast comprises a heel recess and a toe recess configured to receive a heel ballast weight and a toe ballast weight, respectively; wherein the toe ballast weight comprises a toe top surface and a toe front surface that are exposed to the interior cavity; wherein the heel ballast weight comprises a heel top surface and a heel front surface that are exposed to the interior cavity.

12. The golf club head of claim 11, wherein the weighted ballast comprises a front surface that is contoured towards the towards the rearward region to define an undercut.

13. The golf club head of claim 11, wherein the toe ballast weight and the heel ballast weight are formed of a tungsten material.

14. The golf club head of claim 13, wherein the toe ballast weight comprises a mass between 5 and 60 grams and the heel ballast weight comprises a mass between 5 and 60 grams.

15. The golf club head of claim 14, wherein the heel ballast weight comprises a mass between 13 and 35 grams and the toe ballast weight comprises a mass between 13 and 35 grams.

16. The golf club head of claim 12, wherein the weighted ballast has a top surface that is curved such that a heel end and a toe end of the weighted ballast extend further from the sole than a middle of the weighted ballast.

17. The golf club head of claim 11, wherein the toe ballast weight and heel ballast weight are welded to the weighted ballast.

18. The golf club head of claim 11, wherein the hollow body comprises a first material with a first density and the toe ballast weight and the heel ballast weight comprise a second material with a second density, wherein the second density is greater than the first density.

19. The golf club head of claim 11, further comprising a support member extending across the rear opening, wherein the support member connects at least two portions of the lap joint edge.

20. A golf club head comprising:

a strike face;
a body coupled to the strike face to define an internal cavity, the body comprising: a front have a front perimeter configured to receive the strike face; a heel, a toe opposite the heel, a sole, a top rail opposite the sole, a rear opposite the front and extending between the top rail and the sole, the rear defining a rear opening and a lap joint bordering the rear opening; and a ballast located in the interior cavity at a junction of the sole and the rear extending in a heel toe direction, wherein the ballast comprises a ballast bottom surface, a ballast rear surface, a ballast toe surface, and a ballast heel surface, wherein the ballast defines a ballast recess; and a ballast weight disposed in the ballast recess, wherein the ballast weight is formed of a ballast weight material that is more dense than a remainder of the body, wherein the ballast weight comprises a ballast weight bottom surface configured to abut the ballast bottom surface, a ballast weight rear surface configured to abut the ballast rear surface, a ballast weight toe surface configured to abut the ballast toe surface, and a ballast weight heel surface configured to abut the ballast heel surface.
Patent History
Publication number: 20250073546
Type: Application
Filed: Nov 21, 2024
Publication Date: Mar 6, 2025
Applicant: KARSTEN MANUFACTURING CORPORATION (Phoenix, AZ)
Inventors: Josh A. Degerness (Phoenix, AZ), Eric J. Morales (Laveen, AZ), Suraj Megharaja (Phoenix, AZ), Mark C. Bloxham (Phoenix, AZ), Calvin S. Wang (Chandler, AZ), Evan R. Greer (Peoria, AZ), Matthew T. Schier (Phoenix, AZ), Travis D. Milleman (Cave Creek, AZ)
Application Number: 18/955,666
Classifications
International Classification: A63B 53/04 (20060101); A63B 53/08 (20060101); A63B 60/02 (20060101);