Shaft for use in golf clubs and other shaft-based instruments and method of making the same
A shaft for use in a golf-club or other shaft-based instrument, including a base member and a metal layer, and a method of making the same.
1. Field of the Inventions
The present inventions relate generally to shaft-based instruments and, more particularly, to shafts for use in golf clubs and other shaft-based instruments.
2. Description of the Related Art
Over the years, there have been a variety of attempts to improve shaft-based instruments such as golf clubs, ski poles and hockey sticks. With respect to golf clubs, many substitutes have been introduced for the hard wood shafts originally used in golf club drivers and irons. Early substitute materials included stainless steel and aluminum. More recently, carbon fiber reinforced resin shafts have become popular. Such shafts are typically hollow and consist of a shaft wall formed around a tapered mandrel. The use of fiber reinforced resin has allowed golf club manufacturers to produce shafts having varying degrees of strength, flexibility and torsional stiffness. Carbon fiber reinforced resin shafts have also become popular in other shaft-based instruments. As such, manufacturers are able to produce shafts which suit the needs of a wide variety of applications.
Nevertheless, manufactures of shaft-based instruments are faced with a variety of design issues that have proven difficult to overcome using conventional fiber reinforced resin technologies. One issue associated with shaft design is related to the torsional and longitudinal stiffness of the shafts and, in the golf club shaft context, the attempts of designers to increase torsional stiffness (especially near the club head) in order to improve shot accuracy and increase longitudinal stiffness in order to cope with the ever increasing swing velocities of golfers. Another issue associated with shaft design is the location of the shaft flex point. More specifically, the inability of shaft designers to precisely predict the location of the flex point when designing a shaft without using excessive amounts of composite material, which can lead to weight and thickness issues, can be problematic. Breakage prevention is another important design issue. With respect to golf club shafts, for example, breakage often occurs within the region of the main body section that is adjacent to the club head.
SUMMARY OF THE INVENTIONSThe general object of the present inventions is to provide shafts that eliminate, for practical purposes, the aforementioned problems. In particular, one object of the present inventions is to provide golf club shafts and other shafts that have greater torsional and longitudinal stiffness than conventional fiber reinforced resin shafts. Another object of the present inventions is to provide golf club shafts and other shafts which facilitate precise location of the flex point. Still another object of the present inventions is to provide golf club shafts and other shaft that resist breakage.
In order to accomplish these and other objectives, a shaft in accordance with the present invention includes a plurality of fiber reinforced resin layers and a metal layer. The metal layer may, for example, be formed from a lightweight, high modulus of elasticity and tensile strength material such as titanium. Such a shaft provides a number of advantages over conventional shafts. For example, the metal layer augments the shafts torsional and longitudinal stiffness. Shaft designers can also adjust the location of the flex point by simply adjusting the length of the metal layer. The metal layer will also prevent breakage. In golf club shafts, for example, the metal layer may extend along the tip section from a point within the club head hosel to a point outside the hosel. This arrangement strengthens the area of the tip section adjacent to the club head that is a frequent area of breakage in conventional golf club shafts and also provides torsional rigidity.
The above described and many other features and attendant advantages of the present inventions will become apparent as the inventions become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGSDetailed description of preferred embodiments of the inventions will be made with reference to the accompanying drawings.
The following is a detailed description of the best presently known modes of carrying out the inventions. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the inventions. The scope of the inventions is defined by the appended claims. Additionally, although the present inventions are described herein in the golf club shaft context because the inventions are particularly well suited to golf club shafts, the inventions are not so limited. The inventor herein has determined that present inventions have application in other shaft-based devices such as, for example, ski poles and hockey sticks.
As illustrated for example in
It should be noted that the dimensions of the shafts illustrated in the drawings are exaggerated and often not to scale. Commercial embodiments of golf club shafts in accordance with the present inventions may range from about 33 inches to about 46 inches in overall length. With respect to the tip section 20, the length may range from about 3 inches to about 8 inches and the outer diameter (OD) may range from about 0.370 inch to about 0.500 inch for irons and from about 0.335 inch to about 0.500 inch for woods. The typical club head hosel, i.e. the portion of the club head that receives the shaft, is about 1 inch. Thus, the tip section 20 will extend proximally beyond the hosel in the manner illustrated in
The exemplary shaft 12 consists of two primary components—a polymer base member 28 and a metal layer 30. Referring to
The exemplary base member 28 may be manufactured using any of the materials typically used to produce composite resin/fiber golf club shafts. Suitable resins include, for example, thermosetting resins or polymers such as polyesters, epoxies, phenolics, melamines, silicones, polimides, polyurethanes and thermoplastics. Suitable fibers include, for example, carbon-based fibers such as graphite, glass fibers, aramid fibers, and extended chain polyethylene fibers. After the successive layers of fiber reinforced resin are wrapped around the mandrel, the shaft is cured in an oven. Curing times and temperatures depend on the polymer used in the composite and are well known to those of skill in the art.
The metal layer 30 in the exemplary embodiments is preferably formed from a metal having relatively high tensile strength (about 200-350 Mpa) and a relatively high modulus of elasticity (about 70-200 GPa). Commercially pure titanium, 7000 series aluminum, and low alloy steel are suitable metals. Aluminum alloys, such as scandium-aluminum alloys, that have the desired tensile strength and modulus of elasticity characteristics may also be used. The thickness of the metal layer 30 will range from about 0.001 inch to about 0.006 inch when formed from these materials. Although not so limited, the metal layer will preferably be positioned such that it extends along the shaft from a point on the shaft within the club head hosel to a point on the shaft outside the club head hosel. This is because the area adjacent to the club head 16 is the area which is most effected by torsional forces and is also the area where conventional shafts are most likely to break. As illustrated in
The length of the metal layer 30 will depend upon the dimensions of the overall shaft 12 and the intended shaft characteristics, such as stiffness and flex point location. Suitable lengths for golf club shafts range from about 5 inches to about 30 inches. However, there may be some instances where the metal layer 30 would extend over the entire length of the shaft. There may also be some instances where the metal layer 30 would extend over only a portion of the tip section 20 that will not be within the club head hosel when the golf club is assembled (
The metal layer 30 is wrapped around the fiber reinforced resin composite base member 28 through the use of a rolling process during manufacturing. The rolling process may be performed by hand or with a rolling table. The metal sheet (or sheets) that make up the metal layer 30 should preferably be sized such that the metal wraps exactly a whole number multiple of times around the base member 28, e.g. exactly one time or exactly two times, but not 2½ times, in order to prevent the formation of spines.
Preferably, there will be a bonding layer 38 that secures the base member 28 and metal layer 30 to one another in the manner illustrated for example in
The metal layer 30 may have enough metal memory to cause it to unwind a bit after the rolling process. Thus, although not required, the exemplary shaft 12 also includes an outer layer 40 that is used to hold down the metal layer 30. Suitable outer layers include high resin content scrim cloth (about 40% resin content by weight or higher) and fiber reinforced resin that is pre-impregnated with epoxy (about 40% resin content or higher). The scrim cloth is advantageous in that the metal layer 30 will be visible through the scrim cloth. As shown in
Another suitable manufacturing technique is the bladder mold process. Here, the fiber reinforced resin, metal, adhesive, outer layers are prearranged and then wrapped together around a bladder with a small mandrel inside the bladder. A heated mold is placed over the wrapped bladder, the bladder is expanded to force the material against the mold, and the shaft is then cured in the mold. Curing times and temperatures depend on the polymer used in the composite and are well known to those of skill in the art. Filament winding techniques, where the process is stopped to change materials, may also be used. No adhesive is required here because the graphite tow is wet with epoxy or other adhesive.
As noted above, the tip section 20 is substantially cylindrical, while the main body section 22 has a frusto-conical shape with a substantially constant taper. In some embodiments, such as that illustrated in
The rolling issue may also be obviated by forming a metal layer 30″ from a metal sheet (or “blank”) 48 having a plurality of longitudinally extending slits 50 formed therein in the manner illustrated for example in
Although the present inventions have been described in terms of the preferred embodiment above, numerous modifications and/or additions to the above-described preferred embodiments would be readily apparent to one skilled in the art. By way of example, but not limitation, the present inventions include golf clubs including any of the shafts described above. It is intended that the scope of the present inventions extends to all such modifications and/or additions and that the scope of the present inventions is limited solely by the claims set forth below.
Claims
1-43. (canceled)
44. A golf club shaft for use with a golf club head including a hosel having a predetermined length, the golf club shaft comprising:
- a polymer base member defining a tip end, a tip section adapted to be inserted into the hosel, a main body section, a grip section, and a butt end; and
- a metal layer extending around and secured to at least a portion of the base member and defining distal and proximal ends and first and second longitudinally extending side edges that abut one another.
45. A golf club shaft as claimed in claim 44, wherein the base member comprises a plurality of resin layers.
46. A golf club shaft as claimed in claim 45, wherein the plurality of resin layers comprises a plurality of fiber reinforced resin layers.
47. A golf club shaft as claimed in claim 46, wherein the base member defines a longitudinal axis and the plurality of fiber reinforced resin layers include a group of layers with fibers angled with respect to the longitudinal axis of the shaft and a group of layers with fibers substantially parallel to the longitudinal axis.
48. A golf club shaft as claimed in claim 44, wherein the metal layer is located such that the distal end of the metal layer is less than the predetermined length from the tip end and the proximal end of the metal layer is greater than the predetermined length from the tip end.
49. A golf club shaft as claimed in claim 48, wherein the distal end of the metal layer is substantially aligned with the tip end of the base member.
50. A golf club shaft as claimed in claim 48, wherein the metal layer covers at least a portion of the tip section and at least a portion of the main body section.
51. A golf club shaft as claimed in claim 48, wherein the metal layer covers the entire tip section and at least a portion of the main body section.
52. A golf club shaft as claimed in claim 44, wherein the metal layer is secured to at least a portion of the tip section.
53. A golf club shaft as claimed in claim 52, wherein the metal layer covers the entire tip section.
54. A golf club shaft as claimed in claim 44, wherein the tip section defines a first shape and the main body section defines a second shape different than the first shape.
55. A golf club shaft as claimed in claim 54, wherein the tip section defines a cylindrical shape and the main body section defines a frusto-conical shape.
56. A golf club shaft as claimed in claim 44, further comprising:
- a bonding layer between the base member and the metal layer.
57. A golf club shaft as claimed in claim 56, further comprising:
- an outer layer, including a resin and a cloth within the resin, over the metal layer.
58. A golf club shaft as claimed in claim 44, further comprising:
- an outer layer, including a resin and a cloth within the resin, over the metal layer.
59. A golf club shaft as claimed in claim 44, wherein the longitudinally extending side edges are linear from the proximal end of the metal layer to the distal end of the metal layer.
60. A golf club shaft, comprising:
- a polymer base member defining a circumference, a tip section, a main body section, and a grip section;
- a bent metal sheet on at least a portion of the base member that extends at least once around the circumference of the portion of the base member; and
- an outer layer, formed from a fiber reinforced resin or a resin with a cloth within the resin, covering the bent metal sheet and extending beyond the bent metal sheet.
61. A golf club shaft as claimed in claim 60, wherein the tip section defines a first shape and the main body section defines a second shape different than the first shape.
62. A shaft as claimed in claim 60, further comprising:
- a bonding layer between the base member and the bent metal sheet.
63. A golf club shaft as claimed in claim 60, wherein the polymer base member comprises a plurality of fiber reinforced resin layers.
64. A golf club shaft for use with a golf club head including a hosel having a predetermined length, the golf club shaft comprising:
- a polymer base member defining a tip end, a tip section adapted to be inserted into the hosel, a main body section, a grip section, and a butt end; and
- a metal layer secured to at least a portion of the base member, defining distal and proximal ends and first and second longitudinally extending side edges, and extending around the portion of the base member such that a first portion of the metal layer overlaps a second portion of the metal layer; and
- a bonding layer between the polymer base member and metal and between first and second portions of the metal layer.
65. A golf club shaft as claimed in claim 64, wherein the base member comprises a plurality of resin layers.
66. A golf club shaft as claimed in claim 65, wherein the plurality of resin layers comprises a plurality of fiber reinforced resin layers.
67. A golf club shaft as claimed in claim 64, wherein the metal layer is located such that the distal end of the metal layer is less than the predetermined length from the tip end and the proximal end of the metal layer is greater than the predetermined length from the tip end.
68. A golf club shaft as claimed in claim 67, wherein the distal end of the metal layer is substantially aligned with the tip end of the base member.
69. A golf club shaft as claimed in claim 67, wherein the metal layer covers at least a portion of the tip section and at least a portion of the main body section.
70. A golf club shaft as claimed in claim 67, wherein the metal layer covers the entire tip section and at least a portion of the main body section.
71. A golf club shaft as claimed in claim 64, wherein the metal layer is secured to at least a portion of the tip section.
72. A golf club shaft as claimed in claim 71, wherein the metal layer covers the entire tip section.
73. A golf club shaft as claimed in claim 64, wherein the metal layer extends exactly a whole number multiple of times around the base member.
74. A golf club shaft as claimed in claim 73, wherein the metal layer extends exactly two times around the base member.
75. A golf club shaft as claimed in claim 64, further comprising:
- an outer layer, including a resin and a cloth within the resin, over the metal layer.
76. A golf club shaft as claimed in claim 64, wherein the tip section defines a first shape and the main body section defines a second shape different than the first shape.
77. A golf club shaft as claimed in claim 76, wherein the tip section defines a cylindrical shape and the main body section defines a frusto-conical shape.
78. A golf club shaft as claimed in claim 64, wherein the first portion of the metal layer continuously overlaps the second portion of the metal layer from the distal end to the proximal end.
Type: Application
Filed: Nov 22, 2005
Publication Date: Sep 21, 2006
Inventor: Michael Cheng (Simi Valley, CA)
Application Number: 11/284,769
International Classification: A63B 53/12 (20060101); A63B 53/10 (20060101);