VARIABLE THICKNESS GOLF CLUB HEAD AND METHOD OF MANUFACTURING THE SAME

Abstract

A method of forming a crown of a golf club head including casting the crown of the golf club head, the crown including an internal surface adjacent a hollow interior of the golf club head, and an external surface opposite the internal surface, the crown including a first region and a second region adjacent the first region, the first region including a recess formed in the internal surface, the first region including a sacrificial protrusion on the external surface extending outwards beyond the second region; applying a mask to the external surface of the second region; exposing the crown of the golf club head to an etching chemical, wherein the etching chemical removes the sacrificial protrusion from the external surface of the crown; removing the etching chemical from the crown of the golf club head; and removing the mask from the second region.

Description

RELATED APPLICATIONS

The current application is a continuation-in-part (CIP) of U.S. patent application Ser. No. 14/330,165, filed on Jul. 14, 2014, currently pending, which is a continuation-in-part (CIP) of U.S. patent application Ser. No. 13/467,102, filed on May 9, 2012, abandoned, the disclosure of which are incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a variable thickness golf club head and a method of manufacturing the same. More specifically, the present invention relates to systems, devices, and methods related to constructing portions of a golf club head incorporating variable thickness.

BACKGROUND OF THE INVENTION

Ever since the metalwood golf club burst onto the scene to replace the traditional persimmon wood, golf club designers have constantly sought to find ways to improve upon this groundbreaking design.

U.S. Pat. No. 5,474,296 to Schmidt et al. illustrate one of the earlier attempts to improve upon the design opportunity created by a hollow metalwood golf club by disclosing a golf club with a variable faceplate thickness. One way a variable faceplate thickness improves the performance of a metalwood club is by reducing the amount of weight at low stress areas of the striking faceplate to create more discretionary weight that can be placed at alternative locations in the golf club head to improve the performance of the golf club head. In addition to the above benefit, the incorporation of variable faceplate thickness can also improve upon the performance of the golf club head by adjusting the coefficient of restitution of the striking face.

U.S. Pat. No. 6,863,626 to Evans et al. illustrates this secondary benefit of adjusting the coefficient of restitution of a golf club by disclosing a golf club having a striking plate with regions of varying thickness. More specifically, U.S. Pat. No. 6,863,626 identifies this benefit by indicating that striking plate having regions of varying thickness allows for more compliance during impact with a golf ball, which in turn, could generate more ballspeed.

U.S. Pat. No. 7,137,907 to Gibbs et al. illustrates the ability to further improve upon the design of a striking face having a variable face thickness for a purpose that is different from saving weight and improving coefficient of restitution. More specifically, U.S. Pat. No. 7,137,907 illustrates a way to expand upon the “sweet spot” of a golf club head in order to conform to the rules of golf that puts a cap on the maximum coefficient of restitution allowed by a golf club. U.S. Pat. No. 7,137,907 does this by disclosing a golf club face or face insert wherein the face has an interior surface with a first thickness section and a second thickness region. The first thickness section preferably has a thickness that is at least 0.025 inch greater than the thickness of the second thickness region. The face or face insert with variable thickness allows for a face or face insert with less mass in a golf club head that conforms to the United States Golf Association regulations.

With the incorporation of variable face thickness into hollow metalwood type golf club heads, various methodologies of manufacturing have been developed to create this complicated geometry. U.S. Pat. No. 6,354,962 to Galloway et al. illustrates one methodology to create a striking wherein the face member is composed of a single piece of metal, and is preferably composed of a forged metal material, more preferably a forged titanium material. However, due to the need for precise geometry, the variable face geometry created by this conventional forging process may often exhibit waviness which will often need to be machined to the exact precise geometry. U.S. Pat. No. 7,338,388 to Schweigert et al. discusses this machining process by utilizing a ball end mill revolving about an axis generally normal to the inner surface of the face plate at an initial location on a circumferential intersection between the outer edge of the central thickened region and a transition region. The inner surface of the face plate is machined by moving the revolving ball end mill in a radial direction outwardly toward and through the transition region and the peripheral region to machine the inner surface of the face plate creating a tool channel having a width as the ball end mill traverses the transition region and thereby vary the thickness of the face plate in the tool path.

Although the machining process described above may be capable of creating a very precise geometry, the resulting striking face could still be flawed due to some inherent machining side effects. Undesirable side effects such as the existence of machine marks, circular cutting patterns, discontinuity of machine lines, starting and stopping marks, and/or machine chatters could all adversely affect the striking face.

U.S. Pat. No. 6,966,848 to Kusumoto attempts to address this issue of trying to create an improved striking face of a golf club head by disclosing a methodology wherein the stamped out face material is placed in a die assembly, wherein the face material is being thinned by causing the face material to plastically deform via pressing an upper die together with the lower die. Although this particular type of conventional forging methodology eliminates the adverse side effects of machining above described, it suffers from an entirely different set of adverse side effect. More specifically, the conventional forging of a face insert suffers from lack of material consistency and material transformation that results when a material is melted and plastically deformed resulting in grain growth and oxidation; both of which can lower the material strength of a material.

In addition to the above flaws in the current manufacturing techniques, these flaws of the current techniques become even more apparent when a designer seeks to further advance the performance of a striking face by implementing non-symmetrical geometries that would either require extensive machining, or extreme sacrifice in material property depending on the solution selected.

Hence, as it can be seen from above, despite all the attempts in addressing the consistency and accuracy issue in creating the variable thickness geometry in a golf club head, the current art falls short in providing a methodology that can address the issues above. Ultimately, it can be seen from above that there is a need in the art for a methodology of creating portions of a golf club head with variable thickness without relying on conventional property changing forging techniques or simple machining techniques to ensure more precision and consistency for basic symmetrical geometries and even extreme asymmetrical geometries.

BRIEF SUMMARY OF THE INVENTION

One non-limiting embodiment of the present technology includes a method of forming a crown of a golf club head, including: casting the crown of the golf club head, the crown of the golf club head including an internal surface adjacent a hollow interior of the golf club head, and an external surface opposite the internal surface, the crown of the golf club head including a first region and a second region adjacent the first region, the second region substantially surrounding the first region, the first region including a recess formed in the internal surface, the first region including a sacrificial protrusion on the external surface extending outwards beyond the second region, wherein the first region of has an as-cast thickness T₁, and thickness T₁ is greater than or equal to 0.48 mm; applying a mask to the external surface of the second region; exposing the crown of the golf club head to an etching chemical, wherein the etching chemical removes the sacrificial protrusion from the external surface of the crown; removing the etching chemical from the crown of the golf club head; and removing the mask from the second region.

One non-limiting embodiment of the present technology includes a method of forming a portion of a golf club head, including: casting the portion of the golf club head, the portion of the golf club head including an internal surface adjacent a hollow interior of the golf club head, and an external surface opposite the internal surface, the portion of the golf club head including a first region and a second region adjacent the first region, the first region including a recess formed in the internal surface, the first region including a sacrificial protrusion on the external surface extending outwards beyond the second region; applying a mask to the external surface of the second region; exposing the portion of the golf club head to an etching chemical; removing the etching chemical from the portion of the golf club head; and removing the mask from the second region.

An additional non-limiting embodiment of the present technology includes polishing the external surface of the portion of the golf club head.

In an additional non-limiting embodiment of the present technology the first region of has an as-cast thickness T₁, and thickness T₁ is greater than or equal to 0.48 mm.

In an additional non-limiting embodiment of the present technology the thickness T₁ of the first region, after exposing the portion of the golf club head to an etching chemical, is reduced to less than or equal to 0.45 mm.

In an additional non-limiting embodiment of the present technology the thickness T₁ of the first region, after exposing the portion of the golf club head to an etching chemical, is reduced to less than or equal to 0.35 mm.

In an additional non-limiting embodiment of the present technology the thickness T₁ of the first region, after exposing the portion of the golf club head to an etching chemical, is reduced to less than or equal to 0.25 mm.

In an additional non-limiting embodiment of the present technology exposing the portion of the golf club head to an etching chemical removes the sacrificial protrusion from the first region.

In an additional non-limiting embodiment of the present technology exposing the portion of the golf club head to an etching chemical is completed when the external surface is substantially flush at the intersection of the first region and the second region.

In an additional non-limiting embodiment of the present technology the second region substantially surrounds the first region.

In an additional non-limiting embodiment of the present technology the second region has a thickness T₂, and wherein the recess has a depth D_r, and wherein D_r is greater than or equal to T₂/2.

One non-limiting embodiment of the present technology includes a method of forming a crown of a golf club head, including: casting the crown of the golf club head, the crown of the golf club head including an internal surface adjacent a hollow interior of the golf club head, and an external surface opposite the internal surface, the crown of the golf club head including first region and a second region adjacent the first region, the first region including a recess formed in the internal surface, the first region including a sacrificial protrusion on the external surface extending outwards beyond the second region; applying a mask to the external surface of the second region; exposing the crown of the golf club head to an etching chemical, wherein the etching chemical removes the sacrificial protrusion from the external surface of the crown; removing the etching chemical from the crown of the golf club head; and removing the mask from the second region.

An additional non-limiting embodiment of the present technology includes including polishing the external surface of the crown of the golf club head.

In an additional non-limiting embodiment of the present technology the first region of has an as-cast thickness T₁, and thickness T₁ is greater than or equal to 0.48 mm.

In an additional non-limiting embodiment of the present technology the thickness T₁ of the first region, after exposing the crown of the golf club head to an etching chemical, is reduced to less than or equal to 0.45 mm.

In an additional non-limiting embodiment of the present technology the thickness T₁ of the first region after exposing the crown of the golf club head to an etching chemical is reduced to less than or equal to 0.35 mm.

In an additional non-limiting embodiment of the present technology the thickness T₁ of the first region after exposing the crown of the golf club head to an etching chemical is reduced to less than or equal to 0.25 mm.

In an additional non-limiting embodiment of the present technology exposing the crown of the golf club head to an etching chemical is completed when the external surface is substantially flush at the intersection of the first region and the second region.

In an additional non-limiting embodiment of the present technology the second region substantially surrounds the first region.

In an additional non-limiting embodiment of the present technology the second region has a thickness T₂, and wherein the recess has a depth D_r, and wherein D_r is greater than or equal to T₂/2.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.

FIG. 1 shows a perspective view of a golf club head that is disassembled.

FIG. 2 shows an internal rear view of a face insert.

FIG. 3 shows a cross-sectional view of a face insert.

FIG. 4a shows a side view of one of the steps used to create a face insert.

FIG. 4b shows a side view of one of the steps used to create a face insert.

FIG. 4c shows a side view of one of the steps used to create a face insert.

FIG. 5a shows a side view of one of the steps used to create a face insert.

FIG. 5b shows a side view of one of the steps used to create a face insert.

FIG. 5c shows a side view of one of the steps used to create a face insert.

FIG. 6a shows a cross-sectional view of a face insert.

FIG. 6b shows a cross-sectional view of a face insert.

FIG. 7 shows a perspective view of one embodiment a golf club head including a striking face, a crown, a sole, and a hosel.

FIG. 8 shows a front elevation view of the golf club head of FIG. 7.

FIG. 9 shows a top view of the external surface of one embodiment of a crown of a golf club head.

FIG. 10 shows a bottom view of the internal surface of the crown of FIG. 9.

FIG. 11 shows a cross-sectional view of the crown of FIG. 9 taken across cross-sectional line C-C′ as shown in FIGS. 9 and 10.

FIG. 12 shows one embodiment of a crown of a golf club head including heel toe ribs.

FIG. 13 shows one embodiment of a crown of a golf club head including a criss-cross rib pattern.

FIG. 14A shows a cross sectional view of the first step of the stamped forging process wherein the crown is placed between a top punch and a bottom cavity configured to deform the crown.

FIG. 14B shows a cross sectional view of the next step of the stamped forging process wherein the top punch compresses towards the bottom cavity to alter the shape and geometry of the crown.

FIG. 14C shows the next step of the stamped forging process wherein the top punch is retracted away from the bottom cavity and off of the crown.

FIG. 15A shows a cutter about to remove excess material from the crown and the cutting line.

FIG. 15B shows an intermediary stage of the cutting process wherein the cutter begins to remove excess material from the crown along the cutting line.

FIG. 15C shows the crown wherein the excess material has been removed by the cutter.

FIG. 16A shows the crown positioned between an external die and an internal die.

FIG. 16B shows the crown after being bent to the desired curvature by the internal die and external die.

FIG. 17A shows a cross sectional view of a deformed crown between a curved top punch and a curved bottom cavity.

FIG. 17B shows a cross sectional view of the crown being machined by the cutter.

FIG. 17C shows a cross sectional view of the crown after being machined by the cutter.

FIG. 18 illustrates a perspective view of a golf club head 1000 including a striking face 1100, a crown 1200, a sole 1300, and a hosel 1400.

FIG. 19 illustrates a perspective view of the golf club head 1000 of FIG. 18, including a thin region 1230 located in the crown 1200.

FIG. 20 illustrates a cross-sectional view of the crown 1200 of FIG. 19.

FIG. 21A illustrates a cross-sectional view of the crown after casting.

FIG. 21B illustrates a cross-sectional view of the crown after masking.

FIG. 21C illustrates a cross-sectional view of the crown during etching.

FIG. 21D illustrates a cross-sectional view of the crown after removing the masking.

FIG. 22 illustrates the method of creating variable thickness geometries in golf club heads.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description describes the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

Various inventive features are described below and each can be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below.

FIG. 1 of the accompanying drawings shows a perspective view of a golf club head 100 wherein a body portion 102 and a face insert 104 are disassembled to show the variable face thickness at a rear portion of the face insert 104. It should be noted in FIG. 1 the golf club head has the face insert 104 forming the striking face portion of the golf club head 100 as one of the exemplary embodiments. However, a face insert 104 type geometry is not the only way to form the striking face portion, in fact numerous other geometries can be used to form the striking face portion such as a C shaped face cup, a L shaped face cup, a T shaped face cup, or any other suitable geometry all without departing from the scope and content of the present invention.

FIG. 2 of the accompanying drawings shows a more detailed enlarged perspective view of a face insert 204 in accordance with an exemplary embodiment of the present invention. More specifically, the internal back view of the face insert 204 allows the face center 210, central region 212, transition region 214, and the perimeter region 216 to all be easily shown. In addition to showing the various regions, FIG. 2 of the accompanying drawings shows a cross-sectional line A-A′ horizontally dividing the face insert 204 to illustrate the relative thicknesses of the various regions in FIG. 3. This cross-sectional line A-A′ may also be known as the horizontal dividing line, spanning horizontally through the heel and toe portion of said face insert passing through a face center 210. FIG. 2 also shows a vertical dividing line B-B′, that spans vertically through the crown and sole portion of said face insert passing through a face center 210.

FIG. 3 of the accompanying drawings shows a cross-sectional view of the face insert 304 taken across cross-sectional line A-A′ as shown in FIG. 2. It should be noted that FIG. 3 of the present invention shows a central region 312 having a first thickness d1, a first transition region 314 having a second thickness d2, a first perimeter region 316 having a third thickness d3, a second transition region 313 having a fourth thickness d4, and a second perimeter region 315 having a fifth thickness d5. In one exemplary embodiment, wherein the geometry of the variable face thickness is symmetrical, the thickness of the first and second transition regions 313 and 314 are the same and the thickness of the first and second perimeter region 315 and 316 are the same. It should be noted that due to the fact that the transition regions 313 and 314 are constantly transitioning in thickness from the central region 312 to the perimeter regions 315 and 316, the thickness of the transition regions 313 and 314 are measured at the center of the transition regions 313 and 314. In some instances it is preferred to have symmetry in the variable face thickness geometry, as it makes for fairly simple and straight forward machining. However, the symmetrical geometry may not truly optimize the weight and performance characteristics of a striking face, and has generally stemmed from the machining problems that can come with asymmetrical geometries.

Hence, in accordance with an alternative and preferred embodiment of the present invention, the face insert 304 may have an asymmetrical geometry. More specifically, the first transition region 314 may have a second thickness d2 that is different from the fourth thickness d4 of the second transition region 313, and the first perimeter region 316 may have a third thickness d3 that is different from the fifth thickness d5 of the second perimeter region 315. Removing the restriction of symmetrical variable face thickness geometry removes unnecessary design restrictions to allow a golf club designer to truly optimize the face design. In fact, the preference for symmetrical face geometries in a face insert has always been driven by manufacturing preferences. In one exemplary embodiment, a golf club designer could further thin out different regions of the striking face that is not subjected to the highest level of stress, creating more discretionary mass to be moved to different regions of the golf club head itself.

In this exemplary embodiment, thickness d1 of the central region 312 may generally be greater than about 3.0 mm, more preferably greater than about 3.30 mm, and most preferably greater than about 3.60 mm. Thickness d2 and d4 of the transition regions 314 and 313 respectively may generally decrease from about 3.60 mm to about 2.7 mm, more preferably from about 3.60 mm to about 2.65 mm, and most preferably from about 3.60 mm to about 2.60 mm. Finally, thickness d3 and d5 of perimeter regions 316 and 315 respectively may generally also be decreasing from about 2.70 mm to about 2.55 mm, more preferably from about 2.65 mm to about 2.50 mm, and most preferably from about 2.60 mm to about 2.45 mm.

Based on the above, it can be seen that a new methodology needs to be created to effectively create this constantly changing face thickness without the need to machine complicated geometry that is asymmetrical. The current invention, in order to achieve this goal has created an innovative machining process detailed in FIGS. 4a, 4b, 4c, 5a, 5b, and 5c shown in the later figures.

FIG. 4a through FIG. 4c illustrates graphical depiction of the new innovative face insert forming technique associated with an exemplary embodiment of the present invention called “stamped forging”. Although this new innovative forming technique may have some similarities to the conventional forging process, it is completely different. In fact, the conventional forging process involves deformation of the face insert 404 pre-form material to create the material flow into a cavity. This melting of the material is undesirable when used to form the striking face portion of the golf club head, as the melting of the material, combined with the phase transformation of the material, could result in grain growth and oxidation of the titanium material, both of which diminishes the material strength of titanium.

The current process is completely different from the conventional forging process because it involves the elements of stamping as well as forging, and can be more accurately described as “stamped forging” or “embossed forging”. During this “stamped forging” or “embossed forging” process the face-insert 404 pre-form does not experience any phase transformation, but is merely warmed to a malleable temperature to allow deformation without the actual melting of the face insert 404 pre-form.

More specifically, in FIG. 4a, a side view of the first step in the current forming technique is shown. In FIG. 4a, the various components used for the formation of the face insert 404 such as the top punch 421 and bottom cavity 422 are shown in more detail. More specifically, as it can be seen from FIG. 4a, the top punch 421 has a protrusion 424 created in roughly the shape of the desired variable face thickness geometry; while the bottom cavity 422 has a corresponding depression 426 that also roughly corresponds to the shape of the desired variable face thickness geometry. Although not shown in extreme detail, FIG. 4a shows that the bottom cavity 422 could be non-linear along the perimeter edges 427 to create a constantly variable thickness across the entire perimeter surface of the face insert 404 pre-form.

FIG. 4b shows the next step of the current inventive stamped forging methodology wherein the top punch 421 compresses against the bottom cavity 422 to alter the shape and geometry of the face insert 404. Although the current inventive methodology does not involve the melting of the material used to create the face insert 404, the face insert 404 is generally heated up to about 830° C. for about 300 seconds on a conveyor belt to increase the malleability of the face insert 404 to allow for the deformation. In this current exemplary embodiment of the invention the top punch 421 generally applies about 100 MPa of pressure onto the face insert 404 for about 2 seconds to create the desired geometry.

FIG. 4c shows the next step of the current inventive stamped forging methodology wherein the shape of the variable face thickness geometry begins to take place when the top punch 421 is removed from the bottom cavity 422. It should be noted here that in this current exemplary embodiment of the present invention, the side of the face insert 404 that faces the top punch 421 will eventually form the external surface of the face insert 404 as it gets assembled in the golf club head, while the side of the face insert 404 that contacts the bottom cavity 422 will eventually form the internal surface of the face insert 404 as it gets assembled in the golf club head. This type of methodology ensures that a precise geometry could be achieved on the internal side of the face insert 404 without the need for excessive machining, even if a non-symmetrical organic shape is desired to maximize the performance of the face insert 404.

Although the steps described above in FIGS. 4a through 4c may be sufficient to create the desired geometry in some circumstances, additional steps similar to the ones described above may be repeated to achieve more precise and complicated geometries. In the alternative embodiments wherein multiple stamped forging steps are required, the process could be repeated for rough and fine stamped forging without departing from the scope and content of the present invention. In fact, the steps described could be repeated three time, four times, or any number of times necessary to achieve the desired geometry all without departing from the scope and content of the present invention. In cases wherein multiple stamped forging steps are needed, the shape and geometry of the top punch 421 and the bottom cavity 422 may even be slightly different from one another, with each finer mold having a closer resemblance to the final finished geometry.

Once the geometry of the internal surface of the face insert 404 is formed via the above prescribed methodology, the external surface of the face insert 404 can be machined off a flat geometry, which is a significant improvement than the conventional methodology of actually machining in the complicated geometry on the rear internal surface of the face insert 404. FIGS. 5a through 5c illustrate the final steps involved in machining off the excess material in this the current face insert 504 stamped forging methodology.

FIGS. 5a-5c show side views of a face insert 504 together with the bottom cavity 522 after the top punch (not shown) has created the desired geometry by deforming the shape of the face insert 504 in the previous steps. In these final steps, the excess material of the face insert 504 is removed via a cutter 530. The excess material, as shown in this current exemplary embodiment of the present invention, may generally be defined as any material that is above the cutting line 531 shown in FIG. 5a. This cutting line 531 is generally defined by the flat surface that significantly aligns with the bottom of the rear indentation 528 of the formed face insert 504. In fact, in most exemplary embodiments, the cutting line 531 may actually be placed slightly below the bottom of the rear indentation 528 of the formed face insert 504 to allow for a precise finish of the face insert 504.

The position of this cutting line 531 can be important, as it determines the relative thickness of the face insert 504. Hence, in order to more accurately define this cutting line 531, distance d6 and d7 are identified in FIG. 5a. Here, in this current exemplary embodiment distance d6 signifies the distance of the final thickness of the perimeter relative to the perimeter surface of the bottom cavity 522. This distance d6 may generally vary from about 2.2 mm to about 2.6 mm, more preferably from about 2.3 mm to about 2.6 mm, and most preferably from about 2.4 mm to about 2.6 mm. However, as it has already been discussed before the perimeter region of the face insert 504 could very well have a variable thickness, thus making it difficult to determine the thickness of d6; as the thickness d6 would be a function of the perimeter of the face insert 504. Thus, in order to properly index the cutter 530 to remove the correct amount of material from the frontal surface of the striking face 504, an additional thickness d7 is identified; measuring the distance from the bottom of the depression 526 of the bottom cavity 522 to the cutting line 531 from which the removal of material is indexed. Distance d7, as it is shown in this current exemplary embodiment of the present invention, may generally be between about 3.5 mm to about 3.8 mm, more preferably between about 3.6 mm to about 3.7 mm, and most preferably about 3.65 mm.

The cutter 530 shown in this current exemplary embodiment of the present invention may generally be a fly cutter type cutter to ensure a smooth surface that will eventually form the frontal surface of a golf club head, however, numerous other types of cutters may be used without departing from the scope and content of the present invention. More specifically, alternative cutters 530 may include an end mill clutter, a ball nose cutter, a side and face cutter, a woodruff cutter, a shell mill cutter, or any type of milling cutter all without departing from the scope and content of the present invention. In fact, the finished surface could even potentially be achieved by any alternative finishing techniques that could create a flat surface all without departing from the scope and content of the present invention.

FIG. 5b shows an intermediary stage of the cutting process wherein the cutter 530 begins to remove excess material from the formed face insert 504 along cutting line 531. Finally, FIG. 5c shows the finished product of a face insert 504 in accordance with an exemplary embodiment of the present invention wherein the excess material has been removed by the cutter 530. The finished face insert 504 can then be bent to the required curvature to match the bulge and roll of a golf club head and installed to complete the golf club head. As it can be seen from above, the innovative forming and finishing method is a major improvement in simplifying the machining process involved to a simple one pass finish, especially when compared to the conventional method of machining the actual variable thickness geometry. This advantage of not having to machine the actual geometry becomes even more apparent when the variable geometry implemented involves non-symmetrical shapes, as those types of geometries become extremely difficult to machine using conventional machining methods.

FIGS. 6a and 6b show alternative embodiments of the present invention wherein the frontal indentation 628 of the striking face insert 622 are preserved and not machined off. In these embodiments, the frontal indentation 628 could be filled with a secondary material that is different from the material used to create the face insert 622 to create a striking face insert 622 that incorporates multiple materials. The filler 630 in this current exemplary embodiment could be made out of steel, aluminum, tungsten, composites, or any other types of material that can be reasonably adhered to the rear indentation 628 of the face insert 622 without departing from the scope and content of the present invention. The filler 630 material may have a have a second density greater than a density of the material used to create the face insert 622 in one exemplary embodiment of the present invention; however, in an alternative embodiment of the present invention, the filler 630 material may also have a second density that is less than the density of the material used to create the face insert 622 without departing from the scope and content of the present invention. In an alternative embodiment, the frontal indentation 628 could be filled with a filler 630 that is made out of a similar type material as the remainder of the face insert 622 to ensure sufficient bonding and cohesion between the materials. More specifically, in this alternative embodiment, the filler 630 material could be Ti-64, Ti-811, SP-700, ATI-425, or any other type of titanium alloys all without departing from the scope and content of the present invention.

FIG. 6b shows a further alternative embodiment of the present invention wherein the external surface of the face insert 622 could be covered with a cover layer 632 to ensure that the entire external surface of the face insert 622 has the same material to conform with the requirements of the USGA. In one exemplary embodiment of the present invention the cover layer 632 may be made out of titanium type material similar to the remainder of the body; however, different types of titanium alloys could be used without departing from the scope and content of the present invention as long as it is capable of covering the external surface of the face insert 622.

In additional embodiments, the characteristics and methods illustrated and described herein can be applied to other portions of the golf club head which may include for example, the sole, the crown, etc. Each step of the “stamped forging” process described above in reference to the face insert or the striking face can be applied to another portion of the golf club head which may include, for example, the sole, the crown, etc.

FIG. 7 of the accompanying drawings shows a perspective view of a golf club head 1000 including a striking face 1100, a crown 1200, a sole 1300, and a hosel 1400. The golf club head 1000 includes a forward portion 1500 including the striking face 1100 and an aft portion 1600 opposite the striking face 1100. FIG. 8 of the accompanying drawings shows a front elevation view of the golf club head 1000 of FIG. 7. The golf club head 1000 includes a heel portion 1700 adjacent the hosel 1400 and a toe portion 1800 opposite the heel portion 1700. In some embodiments, the golf club head 1000 can comprise a face insert construction. In additional embodiments, the golf club head 1000 can comprise other constructions which may include for example, a C shaped face cup, an L shaped face cup, a T shaped face cup, or any other suitable geometry all without departing from the scope and content of the present invention.

In some embodiments, various portions of the golf club head 1000 such as the striking face 1100, crown 1200, and sole 1300 can be formed separately and adjoined to form the golf club head 1000. It can be advantageous to vary the thickness of the different portions to reduce weight, reduce stress, alter the performance of the golf club head 1000, and even to alter the acoustic characteristics of the golf club head 1000. FIGS. 9-16 illustrate various embodiments and methods of construction of the crown portion 1200 of a golf club head 1000. In additional embodiments, the characteristics and methods illustrated and described herein can be applied to other portions of the golf club head 1000 which may include for example, the sole 1300, the striking face 1100, etc.

FIG. 9 of the accompanying drawings shows a top view of the external surface 1210 of one embodiment of a crown 1200. In some embodiments, including the one illustrated in FIG. 9, the external surface 1210 of the crown 1200 can be smooth to create a clean appearance when viewing the golf club head from the address position. FIG. 9 of the accompanying drawings shows a cross-sectional line C-C′ dividing the crown 1200 to show the relative thicknesses of the various regions in FIG. 11. This cross-sectional line C-C′ may also be known as a crown dividing line, spanning horizontally through the heel 1700 and toe portion 1800 of the crown 1200 and providing a view from the forward portion 1500 looking toward the aft portion 1600 of the crown 1200. FIG. 10 of the accompanying drawings shows a bottom view of the internal surface 1220 of the crown 1200 of FIG. 9. FIG. 10 also shows a cross-sectional line C-C′ dividing the crown 1200 to show the relative thicknesses of the various regions in FIG. 11

FIG. 11 of the accompanying drawings shows a cross-sectional view of the crown 1200 taken across cross-sectional line C-C′ as shown in FIGS. 9 and 10. In some embodiments the crown 1200 can include variable thickness. The crown 1200 can include at least one thick region 1240 and at least one thin region 1230. In some embodiments, as illustrated in FIGS. 10 and 11, the crown 1200 can include a plurality of thin regions 1230 with a thickness D8 and a plurality of thick regions 1240 with a thickness D9. The thicknesses D8 of the thin regions 1230 is measured at the center of the thin regions 1230 and the thickness D9 of the thick regions 1240 is measured at the center of the thick regions 1240. The thickness in the transition regions between the thick regions 1240 and thin regions 1230 can vary between the thickness D9 of the thick region 1240 and the thickness D8 of the thin region 1230. In some embodiments, the transition regions between the thick regions 1240 and thin regions 13230 can comprise a taper or a curve. In additional embodiments, the crown 1200 can include additional regions with thicknesses different than the thin regions 1230 and thick regions 1240. In some embodiments, the thickness of the thin region 1230 can be thicker in the forward portion 1500 and thinner in the aft portion 1600.

In some embodiments, the thickness D8 of the thin regions 1230 can generally be between 0.1 mm and 1.0 mm. In some embodiments, the thickness D8 of the thin regions 1230 can generally be between 0.2 mm and 0.5 mm. In some embodiments, the thickness D8 of the thin regions 1230 can generally be between 0.3 mm and 0.4 mm. In some embodiments, the thickness D8 of the thin regions 1230 can generally be between 0.325 mm and 0.375 mm. In some embodiments, the thickness D8 of the thin regions 1230 can generally be between 0.340 mm and 0.360 mm. In some embodiments, the thickness D9 of the thick regions 1240 can generally be between 0.1 mm and 1.0 mm. In some embodiments, the thickness D9 of the thick regions 1240 can generally be between 0.2 mm and 0.8 mm. In some embodiments, the thickness D9 of the thick regions 1240 can generally be between 0.3 mm and 0.7 mm. In some embodiments, the thickness D9 of the thick regions 1240 can generally be between 0.4 mm and 0.6 mm. In some embodiments, the thickness D9 of the thick regions 1240 can generally be between 0.45 mm and 0.55 mm. In some embodiments, the thickness D9 of the thick regions 1240 can generally be between 0.48 mm and 0.52 mm. In some embodiments, the thickness D9 of the thick regions 1240 can generally be between 0.49 mm and 0.51 mm.

The geometry and orientation of the thick regions 1240 and thin regions 1230 can include ribs 1250 extending away from the thin region 1230. In some embodiments, the thick regions 1240 can comprise for example, forward aft ribs 1250 as illustrated in FIGS. 10 and 11. As illustrated in FIG. 11, the ribs 1250 can comprise a protrusion extending into the interior of the golf club head 1000 from the internal surface 1220 of the crown 1200. The ribs 1250 can add structural support to the crown 1200 and the thin regions 1230 can minimize the weight of the crown 1200, providing a golf club manufacturer with the ability to place weight elsewhere in the golf club head 1000 to maximize performance. The thickness D9 of the thick region 1240 comprises both the thickness D8 of the thin region 1230 in addition to the distance the thick region 1240 protrudes away from the inner surface 1220 of the thin region 1230. In some embodiments, the plurality of thick regions 1240 may share the same thickness D9. In some embodiments, the plurality of thin regions 1230 may share the same thickness D8.

In additional embodiments, the thickness of various thick regions 1240 or thin regions 1230 may vary in order to optimize the performance of the golf club head 1000. In some embodiments, at least one of the plurality of thick regions 1240 can comprise a different thickness than another thick region 1240. In some embodiments, at least one of the plurality of thin regions 1230 can comprise a different thickness than another thin region 1230. In some embodiments, the thickness of at least one thick region 1240 or thin region 1230 may vary along its length. In some embodiments, at least one thick region 1240 can be thicker near the forward portion 1500 of the golf club head 1000 and thinner near the aft portion 1600 of the golf club head. In some embodiments, at least one thick region 1240 can be thicker near the forward portion 1500 and the aft portion 1600 of the golf club head of the golf club head 1000 and thinner in portion between the forward portion 1500 and aft portion 1600. In some embodiments, at least one thin region 1230 can be thicker near the forward portion 1500 of the golf club head 1000 and thinner near the aft portion 1600 of the golf club head. In some embodiments, at least one thin region 1230 can be thicker near the forward portion 1500 and the aft portion 1600 of the golf club head of the golf club head 1000 and thinner in portion between the forward portion 1500 and aft portion 1600. In other embodiments, the thickness of the thick regions 1240 and thin regions 1230 can vary from the heel side of the golf club head 1000 to the toe side.

In additional embodiments, the thick regions 1240 and thin regions 1230 can include additional geometries and orientations, which may include for example, the heel toe ribs 1250 as illustrated in FIG. 12 or the criss-cross rib 1250 pattern as illustrated in FIG. 13. In additional embodiments (not illustrated), thick regions 1240 can extend outward from the external surface 1210 of the crown 1200. In additional embodiments (not illustrated), the thick regions 1240 can both extend inward into the interior of the golf club head 1000 from the internal surface 1220 of the crown 1200 and outwards from the external surface 1210 of the crown 1200.

Machining the geometries described herein can be difficult and cost prohibitive. In some embodiments, the geometries described herein can be constructed utilizing an innovative process called “stamped forging” detailed in FIGS. 14A-C, 15A-C, 16A-B and described herein. During the “stamped forging” process the crown 1200 does not experience any phase transformation, but is merely warmed to a malleable temperature to allow deformation without the actual melting of the crown 1200.

FIG. 14A shows a cross sectional view of the first step of the stamped forging process wherein the crown 1200 is placed between a top punch 2000 and a bottom cavity 3000 configured to deform the crown 1200. The top punch 2000 can comprise a plurality of protrusions 2100 arranged to reflect the pattern of thick regions 1240 in the crown 1200. The bottom cavity 3000 can comprise a corresponding plurality of depressions 3100 which also reflects the pattern of thick regions 1240 in the crown 1200. Although not illustrated, in some embodiments, the top punch engagement surface 2200 or the bottom cavity engagement surface 3200 can vary in depth to vary the thickness among the thin regions 1230 of the crown 1200. In addition, in some embodiments, the depth of the protrusions 2100 in the top punch 2000 and depressions 3100 in the bottom cavity 3000 can vary to create a variable thickness among the plurality of thick regions 1240 of the crown 1200.

FIG. 14B shows a cross sectional view of the next step of the stamped forging process wherein the top punch 2000 compresses towards the bottom cavity 3000 to alter the shape and geometry of the crown 1200. In some embodiments, the crown 1200 can be heated to about 830° C. for about 300 seconds to increase the malleability of the crown 1200 to allow for deformation. In some embodiments, the top punch 2000 generally applies about 100 MPa of pressure onto the crown 1200 for about 2 seconds to create the desired geometry. In other embodiments, the crown 1200 can be heated to about 1080° C. for about 300 seconds to increase the malleability of the crown 1200 to allow for deformation. In additional embodiments, the crown can be heated to a temperature between about 700° C. and 1300° C. In another embodiment, the crown can be heated to a temperature between about 750° C. and 900° C. In another embodiment, the crown can be heated to a temperature between about 800° C. and 850° C. In another embodiment, the crown can be heated to a temperature between about 1000° C. and 1200° C. In another embodiment, the crown can be heated to a temperature between about 1050° C. and 1100° C.

FIG. 14C shows the next step of the stamped forging process wherein the top punch 2000 is retracted away from the bottom cavity 3000 and off of the crown 1200. In some embodiments, the portion of the crown 1200 facing the top punch 2000 will eventually become the external surface 1210 of the crown 1200 while the portion of the crown 1200 facing the bottom cavity 3000 will eventually become be the internal surface 1220 of the crown 1200. This process ensures that a precise geometry can be achieved on the internal surface 1220 of the crown 1200 without the need for excessive machining. In other embodiments, not illustrated, the opposite may be true and the portion of the crown facing the top punch 2000 will eventually become the internal surface 1220 of the crown 1200 while the portion of the crown 1200 facing the bottom cavity 3000 will eventually become be the external surface 1210 of the crown 1200.

Although the steps described above in FIGS. 14A-14C may be sufficient to create the desired geometry in some circumstances, additional steps similar to the ones described above may be repeated to achieve more precise and complicated geometries. In the alternative embodiments wherein multiple stamped forging steps are required, the process could be repeated for rough and fine stamped forging without departing from the scope and content of the present invention. In fact, the steps described could be repeated three time, four times, or any number of times necessary to achieve the desired geometry all without departing from the scope and content of the present invention. In cases wherein multiple stamped forging steps are needed, the shape and geometry of the top punch 2000 and the bottom cavity 3000 may even be slightly different from one another, with each finer mold having a closer resemblance to the final finished geometry.

Once the geometry of the internal surface 1220 of the crown is formed via the above prescribed methodology, the external surface 1210 of the crown can be machined flat. Machining the external surface 1210 flat can be more cost effective then machining the geometry into the internal surface 1220 of the crown 1200. FIGS. 15A-15C illustrated the steps involved in machining off the excess material of the crown 1200. FIGS. 15A-15C show side views of a crown 1200 together with the bottom cavity 3000 after the top punch (not shown) has created the desired geometry by deforming the shape of the crown 1200 in the previous steps. As illustrated in FIGS. 15A-15C, the excess material of the crown 1200 is removed via a cutter 4000. The excess material, as shown in the embodiment illustrated in FIG. 15A, is generally defined as any material that is above the cutting line 4100. In some embodiments, the cutting line 4100 can be located along a flat surface that significantly aligns with the bottom of the indentations 1260 formed in the crown 1200. In most embodiments, the cutting line 4100 can be offset slightly below the bottom of the indentations 1260 of the crown 1200 to allow for a precise finish of the external surface 1210 of the crown 1200.

The position of the cutting line 4100 can be important, as it determines the thickness D8 of the thin region 1230. In order to more accurately define the cutting line 4100, the distance D10 is identified in FIG. 15A. The distance D10 signifies the distance between the bottom cavity engagement surface 3200 and the cutting line 4100. In some embodiments, the distance D10 mirrors the thickness D8 of the thin region 1230 of the crown 1200. However, in some embodiments, the thin region 1230 of the crown 1200 could have a variable thickness, making it difficult to determine the thickness D8 of the crown 1200 and the height of the cutting line 4100 from the bottom cavity engagement surface 3200. The distance D10 may not be consistent across the cross section of the crown 1200 if the bottom cavity engagement surface 3200 is not flat. In such embodiments, the corresponding thickness D8 of the thin region 1230 may vary across the crown 1200. Thus, a distance D11 is identified in FIG. 15A, which represents the distance from the bottom of the depressions 3100 of the bottom cavity to the cutting line 4100. In some embodiments, the distance D11 mirrors the thickness D9 of the thick region 1240 of the crown 1200.

The cutter 4000 may generally be a fly cutter type cutter to ensure a smooth surface that will eventually form the external surface 1210 of the crown 1200, however, numerous other types of cutters 4000 may be used without departing from the scope and content of the present invention. More specifically, alternative cutters 4000 may include an end mill clutter, a ball nose cutter, a side cutter, face cutter, a woodruff cutter, a shell mill cutter, or any type of milling cutter all without departing from the scope and content of the present invention. In fact, the finished surface could even potentially be achieved by any alternative finishing techniques, which may include, for example, polishing, that could create a flat surface all without departing from the scope and content of the present invention.

FIG. 15B shows an intermediary stage of the cutting process wherein the cutter 4000 begins to remove excess material from the crown 1200 along cutting line 4100. Finally, FIG. 15C shows the crown 1200 in accordance with an exemplary embodiment of the present invention wherein the excess material has been removed by the cutter 4000. The crown 1200 can then be bent as illustrated in FIGS. 16A and 16B to the required curvature. The crown 1200 can be removed from the bottom cavity 3000 and positioned between an external die 5000 and an internal die 6000 as illustrated in FIG. 16A. The external die 5000 can comprise a concave engagement surface 5100 configured to engage the external surface 1210 of the crown 1200. The internal die 6000 can comprise a convex engagement surface 6100 configured to engage the internal surface 1220 of the crown 1200. The external die 5000 can be forced towards the internal die 6000, curving the crown 1200 to the desired geometry as illustrated in FIG. 16B. In some embodiments, not illustrated, the internal die 6000 can comprise depressions similar to the bottom cavity 3000 described earlier to receive the ribs 1250 of the crown 1200. As it can be seen from above, the innovative forming and finishing method is a major improvement in simplifying the machining process involved to a simple one pass finish, especially when compared to the alternatives of machining the actual variable thickness geometry or masking off the geometry and utilizing chemical etching techniques.

In another embodiment, the steps of the stamped forging process described in reference to FIGS. 14A-14C and 16A-16C can be completed simultaneously. FIG. 17A shows a cross sectional view of a deformed crown 1200 between a curved top punch 7000 and a curved bottom cavity 8000. The top punch 7000 can be curved, much like the curved external die 5000 illustrated in FIGS. 16A-B, and the engagement surface 7200 comprise a plurality of protrusions 7100 arranged to reflect the pattern of thick regions 1240 in the crown 1200. The bottom cavity 8000 can be curved, much like the curved internal die 6000 illustrated in FIGS. 16A-B, and the engagement surface 8200 can comprise a corresponding plurality of depressions 8100 which also reflect the pattern of thick regions 1240 in the crown 1200. After the crown is deformed by the curved top punch 7000 and curved bottom cavity 8000, excess material can be machined off the crown. FIG. 17B shows a cross sectional view of the crown 1200 being machined by the cutter 4000. FIG. 17C shows a cross sectional view of the crown 1200 after being machined by the cutter 4000. In some embodiments, as illustrated in FIG. 17B, the crown 1200 can remain positioned on the curved bottom cavity 8000 during the machining. In some embodiments, rather than machining a flat surface as described in relation to FIGS. 15A-15C, the cutter 4000 will machine excess material off the crown 1200 to create a curved external surface 1210, as illustrated in FIGS. 17B and 17C, while leaving the ribs 1250 on the internal surface 1220 of the crown.

In additional embodiments, the characteristics and methods illustrated and described herein can be applied to other portions of the golf club head which may include for example, the sole, the striking face, etc. Each step of the “stamped forging” process described above in reference to the crown or the striking face can be applied to another portion of the golf club head which may include, for example, the sole, the striking face, the crown, etc. The “stamped forging” methods described herein are particularly useful for imparting a variable thickness geometry to a portion of a golf club head, particularly one in which the external surface is desired to have a smooth surface and the inside surface desirably includes thick regions of a particular geometry to alter the performance characteristics of the golf club head. Additional thickness variations and geometries of various portions of the golf club head are possible utilizing the methods described herein. For example, the process could be modified such that the variable thickness geometry is exposed on the exterior surface of the golf club head rather than the interior as illustrated and described herein. In addition, the methods described herein can be applied to irons and putters in addition the metal wood clubs illustrated in the Figures. The face of an iron type golf club, for example, could be formed utilizing the stamped forging methods described herein and then welded or bonded to the body of the golf club head.

FIG. 18 illustrates a perspective view of a golf club head 1000 including a striking face 1100, a crown 1200, a sole 1300, and a hosel 1400. The striking face and crowns described earlier were created using a stamped forging process. In some embodiments, it can be advantageous and more cost effective to create portions of the golf club head 1000 via casting. For illustrative purposes, we will assume the golf club head 1000 is a face-pull cast construction, which means the body portion 1610, the majority of the golf club head 1000, is cast and the casting tooling is pulled through a window in the striking face 1100 of the golf club head 1000. Once the body portion 1610 of the golf club head 1000 is cast then a face insert 1110 is welded to the golf club head 1000, filling the window. Other castable constructions are possible and compatible with the construction techniques described herein. Most golf club heads are cast via investment casting techniques, but other casting methods can be used such as sand casting, die casting, etc.

Casting does have its limitations, one of which being the minimum wall thicknesses required. During casting, the molten metal needs to flow through the various portions of the golf club head and that flow can be inhibited by very thin portions. Casting thinner than a minimum castable thickness can lead to voids and porosity in the casting which decrease the strength and increase stress risers in the golf club head. Therefore, it can be impossible to cast some of the geometries described herein if the thin regions are thinner than the minimum castable thickness. One desirable geometry that is difficult to achieve with existing casting methods, is a crown incorporating at least one thin region that is thinner than the minimum castable thickness, one example of which is illustrated in FIGS. 19 and 20. FIG. 19 illustrates a perspective view of the golf club head 1000 of FIG. 18, including a thin region 1230 located in the crown 1200. FIG. 20 illustrates a cross-sectional view of the crown 1200 of FIG. 19. The crown 1200 of the golf club head 1000 includes a variable thickness geometry. The crown 1200 includes an external surface 1210 and an internal surface 1220. The internal surface 1220 is adjacent the hollow interior of the golf club head 1000 and the external surface 1210 is opposite the internal surface 1220. The external surface is substantially smooth. The internal surface includes a recess 1270, causing the crown 1200 to have a thin region 1230 and a thick region 1240. The thin region has a thickness T_thin which is less than the minimum castable thickness. The thick region has a thickness T_thick which is thicker than the thickness T_thin. The recess has a depth D_r.

The minimum castable thickness to create repeatable quality castings is typically greater than or equal to 0.52 mm. Recent developments in casting techniques have had success casting as thin as 0.48 mm. The “minimum castable thickness” will be defined as 0.48 mm herein unless noted otherwise. Typically, the thick region will have a thickness greater than or equal to the minimum castable thickness. The thickness of the thin region T_thin is preferably less than or equal to 0.45 mm. In an additional embodiment, the thickness of the thin region T_thin is preferably less than or equal to 0.35 mm. In an additional embodiment, the thickness of the thin region T_thin is preferably less than or equal to 0.25 mm. The depth of the recess D_r can be greater than or equal to 0.05 mm and less than or equal to 0.35 mm. In an additional embodiment, the depth of the recess D_r can be greater than or equal to 0.15 mm and less than or equal to 0.25 mm. In an additional embodiment, the depth of the recess D_r can be approximately 0.20 mm.

One way to overcome the casting limitations described above, is a new and creative method of creating variable thickness geometries in golf club heads, which is illustrated in FIGS. 21 and 22. This method can be applied to a crown, as described herein, or it can be applied to other portions of a golf club head, which may include for example, the striking face, the sole, etc. The method is particularly applicable to a face-pull cast construction as described above wherein the body portion is cast. The method incorporates specific casting geometries and chemical etching, which can also be referred to as chemical milling or industrial etching. Chemical etching uses etching chemicals to remove material from a golf club head. The material to be removed is normally put in a bath of the etching chemical, a corrosive chemical, sometimes called an etchant, which reacts with the material and causes the material to be dissolved. The amount of material dissolved generally depends on how long the material is exposed to the etching chemical.

Masking can be utilized to prevent the etching chemical from removing material from particular portions of the golf club head. Masking layers are generally formed of inert substances and can be applied to the golf club head in a variety of ways, which may include, for example, dipping, painting, flow coating, electrostatic deposition, adhesive sheet, etc. After the chemical etching is complete, the masking layer can be removed.

The casting and etching method is illustrated in FIGS. 21A-21D and outlined in FIG. 22. First 10001, the body portion of the golf club head is cast. In this embodiment, the desired variable thickness geometry is located in the crown 1200 of the golf club head. FIG. 21A illustrates a cross-sectional view of a crown 1200 after casting. Like the finished crown in FIG. 20, the crown 1200 in FIG. 21A includes a recess on the internal surface 1220. Unlike the finished crown 1200 in FIG. 20, the crown 1200 in FIG. 21A includes a sacrificial protrusion 1280 on the external surface of the crown 1200. The crown 1200 includes a first region 1201 and a second region 1202. The first region 1201 is where the final product will include a thin region 1230. The first region 1201 includes the protrusion 1280 and the recess 1270. The second region is adjacent the protrusion 1280 and recess 1270. In some embodiments, the second region 1202 substantially surrounds the first region 1201. The protrusion 1280 extends outwards beyond the external surface of the second region 1202. The second region 1202 has a thickness T₂. The first region 1201 has a thickness T₁. Thickness T₂ is equal to or greater than the minimum castable thickness in order to facilitate quality and consistent casting results. In some embodiments, thickness T₁ is substantially similar to thickness T₂. The face insert 1110, or any other portion of the golf club head 1000, can be welded to the body portion 1610 at this time as well.

Next 10002, a mask 9000 is applied to the external surface 1210 of the second region 1202 of the crown 1200, as illustrated in FIG. 21B. A mask is not applied to the external surface 1210 of the first region 1201. Masking can be applied the entire casting minus the first region 1201. Additionally, any holes from the hollow golf club head interior to the exterior of the golf club head can be plugged, preventing the etching material from entering the hollow interior of the golf club head.

Next 10003, the crown 1200 is exposed to an etching chemical, as illustrated in FIG. 21C. The etching chemical removes material from the first region 1201, removing the sacrificial protrusion 1280, until the external surface 1210 of the first region 1201 is substantially flush with the external surface 1201 of the second portion. In another embodiment, the etching chemical removes material from the first region 1201, until the thickness T₁ is less than the minimum castable thickness, or until it reaches T_thin. After a specified amount of time 10004, the etching chemical is removed from the golf club head. In one embodiment, the entire club head is dipped into the etching chemical. In another embodiment, a specific portion of the club head can be lowered into an etching chemical, such as the crown, only partially submerging the golf club head.

Finally 10005, the mask 9000 is removed from the second region 1202 of the crown 1200. The end product is a crown 1200, as illustrated in FIG. 21D, where the external surface 1210 of the first region 1201 is substantially flush with the external surface 1210 of the second region 1202. The chemical etching has reduced the thickness of the first region 1201 by removing the sacrificial protrusion, creating a thin region 1230 adjacent the thick region 1240. Some embodiments include an additional step 10006 of polishing the external surface 1210 of the golf club head 100 to ensure the external surface 1210 is smooth and the external surface 1210 of the first region 1201 is substantially flush with the external surface 1210 of the second region 1202.

The casting and chemical etching method described herein can be used to create a variety of variable thickness geometries, including but not limited to those described herein relative to the chemical etching method as well as the stamped forging process.

Other than in the operating example, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moment of inertias, center of gravity locations, loft, draft angles, various performance ratios, and others in the aforementioned portions of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear in the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the above specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

1. A method of forming a crown of a golf club head, comprising:

casting said crown of said golf club head, said crown of said golf club head comprising an internal surface adjacent a hollow interior of said golf club head, and an external surface opposite said internal surface, said crown of said golf club head comprising a first region and a second region adjacent said first region, said second region substantially surrounding said first region, said first region comprising a recess formed in said internal surface, said first region comprising a sacrificial protrusion on said external surface extending outwards beyond said second region, wherein said first region of has an as-cast thickness T1, and thickness T1 is greater than or equal to 0.48 mm;

applying a mask to said external surface of said second region;

exposing said crown of said golf club head to an etching chemical, wherein said etching chemical removes said sacrificial protrusion from said external surface of said crown;

removing said etching chemical from said crown of said golf club head; and

removing said mask from said second region.

2. A method of forming a portion of a golf club head, comprising:

casting said portion of said golf club head, said portion of said golf club head comprising an internal surface adjacent a hollow interior of said golf club head, and an external surface opposite said internal surface, said portion of said golf club head comprising a first region and a second region adjacent said first region, said first region comprising a recess formed in said internal surface, said first region comprising a sacrificial protrusion on said external surface extending outwards beyond said second region;

applying a mask to said external surface of said second region;

exposing said portion of said golf club head to an etching chemical;

removing said etching chemical from said portion of said golf club head; and

removing said mask from said second region.

3. The method of claim 2, further comprising polishing said external surface of said portion of said golf club head.

4. The method of claim 2, wherein said first region of has an as-cast thickness T1, and thickness T1 is greater than or equal to 0.48 mm.

5. The method of claim 4, wherein said thickness T1 of said first region, after exposing said portion of said golf club head to an etching chemical, is reduced to less than or equal to 0.45 mm.

6. The method of claim 4, wherein said thickness T1 of said first region, after exposing said portion of said golf club head to an etching chemical, is reduced to less than or equal to 0.35 mm.

7. The method of claim 4, wherein said thickness T1 of said first region, after exposing said portion of said golf club head to an etching chemical, is reduced to less than or equal to 0.25 mm.

8. The method of claim 2, wherein exposing said portion of said golf club head to an etching chemical removes said sacrificial protrusion from said first region.

9. The method of claim 2, wherein exposing said portion of said golf club head to an etching chemical is completed when said external surface is substantially flush at the intersection of said first region and said second region.

10. The method of claim 2, wherein said second region substantially surrounds said first region.

11. The method of claim 2, wherein said second region has a thickness T2, and wherein said recess has a depth Dr, and wherein Dr is greater than or equal to T2/2.

12. A method of forming a crown of a golf club head, comprising:

casting said crown of said golf club head, said crown of said golf club head comprising an internal surface adjacent a hollow interior of said golf club head, and an external surface opposite said internal surface, said crown of said golf club head comprising a first region and a second region adjacent said first region, said first region comprising a recess formed in said internal surface, said first region comprising a sacrificial protrusion on said external surface extending outwards beyond said second region;

applying a mask to said external surface of said second region;

exposing said crown of said golf club head to an etching chemical, wherein said etching chemical removes said sacrificial protrusion from said external surface of said crown;

removing said etching chemical from said crown of said golf club head; and

removing said mask from said second region.

13. The method of claim 12, further comprising polishing said external surface of said crown of said golf club head.

14. The method of claim 12, wherein said first region of has an as-cast thickness T1, and thickness T1 is greater than or equal to 0.48 mm.

15. The method of claim 14, wherein said thickness T1 of said first region, after exposing said crown of said golf club head to an etching chemical, is reduced to less than or equal to 0.45 mm.

16. The method of claim 14, wherein said thickness T1 of said first region after exposing said crown of said golf club head to an etching chemical is reduced to less than or equal to 0.35 mm.

17. The method of claim 14, wherein said thickness T1 of said first region after exposing said crown of said golf club head to an etching chemical is reduced to less than or equal to 0.25 mm.

18. The method of claim 12, wherein exposing said crown of said golf club head to an etching chemical is completed when said external surface is substantially flush at the intersection of said first region and said second region.

19. The method of claim 12, wherein said second region substantially surrounds said first region.

20. The method of claim 12, wherein said second region has a thickness T2, and wherein said recess has a depth Dr, and wherein Dr is greater than or equal to T2/2.