Composite golf club head

[0002] This application is a continuation-in-part application of U.S. patent application No. 09/877,652, filed on Jun. 8, 2001, now U.S. Pat. No. 6,440,008, which is a continuation of U.S. patent application Ser. No. 09/474,670, filed on Dec. 29, 1999, now U.S. Pat. No. 6,248,025, which is continuation-in-part application of U.S. patent application Ser. No. 08/958,723, filed on Oct. 23, 1997, now U.S. Pat. No. 6,010,411.

[0003] Not Applicable

[0004] 1. Field of the Invention

[0005] The present invention relates to a golf club head with a striking plate composed of a composite material. More specifically, the present invention relates to a golf club head composed of composite material with specifically oriented sheets for more efficient transfer energy to a golf ball at impact.

[0006] 2. Description of the Related Art

[0007] One of the first (if not the first) disclosures of a golf club head composed of a plurality of plies of a pre-preg material is Great Britain Patent Application Number 1201648 which was filed in 1967 on behalf of William Charles Carlton.

[0008] In 1984, U.S. Pat. No. 4,449,707 issued to Hayashi et al., for a Golf Club Head Of Carbon Fiber Reinforced Plastic, based on a Japanese Patent Application originally filed in 1982. The Hayashi Patent discloses surrounding a core with a fiber-reinforced fabric to create a golf club head with a proper center of gravity.

[0009] Another disclosure is U.S. Patent Number 4,545,580 to Tomita et al., for a Wood-Type Golf Club Head, based on a Japanese Patent Application originally filed in 1983. The Tomita Patent discloses a durable golf club head having an outer shell composed of a fiber reinforced plastic material, a foam center core, and an intermediate shell formed of a thermoplastic resin material.

[0010] Yet another disclosure is U.S. Pat. No. 4,630,826 to Nishigaki et al., for Golf Club Head. The Nishigaki Patent discloses body composed of a carbon resin layer and a cast resin layer with a face insert block composed of a ceramic material.

[0011] Still another disclosure is U.S. Pat. No. 4,778,185 to Kurokawa, for Wood-Type Core-Shell Golf Club Heads, based on a Japanese Patent Application originally filed in 1984. The Kurokawa Patent discloses a golf club head composed of a foam core and a shell composed of a material fiber reinforced plastic having long and short fibers.

[0012] Yet another disclosure is U.S. Pat. No. 4,793,616 to Fernandez, for Golf Club. The Fernandez Patent discloses a club head shell composed resin impregnated fibers and ceramic particles within the resin to provide a high strength shell.

[0013] Yet another disclosure is U.S. Pat. No. 5,154,425 to Niskanen et al., for a Composite Golf Club Head. The Niskanen Patent discloses a club head composed of a metal matrix composite of a ceramic matrix composite.

[0014] When a golf club head strikes a golf ball, large impacts are produced that load the club head face and the golf ball. Most of the energy is transferred from the head to the golf ball, however, some energy is lost as a result of the collision. The golf ball is typically composed of polymer cover materials (such as ionomers) surrounding a rubber-like core. These softer polymer materials having damping (loss) properties that are strain and strain rate dependent which are on the order of 10-100 times larger than the damping properties of a metallic club striking plate. Thus, during impact most of the energy is lost as a result of the high stresses and deformations of the golf ball (0.001 to 0.20 inches), as opposed to the small deformations of the metallic club face (0.025 to 0.050 inches). A more efficient energy transfer from the club head to the golf ball could lead to greater flight distances of the golf ball.

[0015] The generally accepted approach has been to increase the stiffness of the club head face to reduce metal or club head deformations. However, this leads to greater deformations in the golf ball, and thus increases in the energy transfer problem.

[0016] Some have recognized the problem and disclosed possible solutions. An example is Campau, U.S. Pat. No. 4,398,965, for a Method Of Making Iron Golf Clubs With Flexible Impact Surface, which discloses a club having a flexible and resilient face plate with a slot to allow for the flexing of the face plate. The faceplate of Campau is composed of a ferrous material, such as stainless steel, and has a thickness in the range of 0.1 inches to 0.125 inches.

[0017] Another example is Eggiman, U.S. Pat. No. 5,863,261, for a Golf Club Head With Elastically Deforming Face And Back Plates, which discloses the use of a plurality of plates that act in concert to create a spring-like effect on a golf ball during impact. A fluid is disposed between at least two of the plates to act as a viscous coupler.

[0018] Yet another example is Jepson et al, U.S. Pat. No. 3,937,474, for a golf Club With A Polyurethane Insert. Jepson discloses that the polyurethane insert has hardness between 40 and 75 shore D.

[0019] Still another example is Inamori, U.S. Pat. No. 3,975,023, for a Golf Club Head With Ceramic Face Plate, which discloses using a face plate composed of a ceramic material having a high energy transfer coefficient, although ceramics are usually harder materials. Chen et al., U.S. Pat. No. 5,743,813 for a Golf Club Head, discloses using multiple layers in the face to absorb the shock of the golf ball. One of the materials is a non-metal material.

[0020] Lu, U.S. Pat. No. 5,499,814, for a Hollow Club Head With Deflecting Insert Face Plate, discloses a reinforcing element composed of a plastic or aluminum alloy that allows for minor deflecting of the face plate which has a thickness ranging from 0.01 to 0.30 inches for a variety of materials including stainless steel, titanium, KEVLAR®, and the like. Yet another Campau invention, U.S. Pat. No. 3,989,248, for a Golf Club Having Insert Capable Of Elastic Flexing, discloses a wood club composed of wood with a metal insert.

[0021] The Rules of Golf established and interpreted by the United States Golf Association (“USGA”) and The Royal and Ancient Golf Club of Saint Andrews, set forth certain requirements for a golf club head. The requirements for a golf club head are found in Rule 4 and Appendix II. A complete description of the Rules of Golf is available on the USGA web page at www.usga.org. Although the Rules of Golf do not expressly state specific parameters for a golf club face, Rule 4-1e prohibits the face from having the effect at impact of a spring with a golf ball. In 1998, the USGA adopted a test procedure pursuant to Rule 4-1e, which measures clubface COR. This USGA test procedure, as well as procedures like it, may be used to measure clubface COR.

[0022] Although the prior art has disclosed many club head composed of composite materials, the prior art has failed to provide a golf club head composed of a composite material that is lightweight, forgiving and has a high coefficient of restitution.

[0023] The present invention provides a golf club head that is composed of a composite material and is forgiving while providing better performance that other composite golf club heads.

[0024] One aspect of the present invention is a composite golf club head that includes a face component, a crown, a sole, weight member and a sole plate. The face component is composed of a plurality of pre-preg plies having fibers. The plurality of pre-preg plies range from 20 to 70 plies. The face component has a striking plate portion and a return portion. The striking plate portion has a thickness in the range of 0.050 inch to 0.250 inch, and the return portion tapers in thickness rearward from a perimeter of the striking plate portion. The crown is composed of a plurality of pre-preg plies ranging from 3 to 20 plies, and the crown is attached to the face component. The sole is also composed of a plurality of pre-preg plies ranging from 3 to 20 plies. The sole has a ribbon portion and a bottom portion. The bottom portion of the sole is attached to the return portion of the face component and the ribbon portion of the sole is attached to the crown. The weighting member is disposed within the plies of pre-preg of the ribbon portion of the sole. The sole plate is attached to an external surface of the bottom portion of the sole, and the sole plate is composed of a metal material.

[0025] Another aspect of the present invention is a golf club head having a body, a weight member, a sole plate and an internal tube. The body is composed of a plurality of plies of pre-preg. The body has a hollow interior defined by a striking plate, a crown, a sole, and a ribbon. The body has a volume of 275 cubic centimeters to 600 cubic centimeters and has a mass under 150 grams. A weight member may be disposed within the plies of pre-preg of the ribbon. The weight member has a mass of from 15 grams to 100 grams. In a golf club head having a volume of 600 cc, additional weighting is not required. The sole plate is attached to an external surface of the sole of the body. The sole plate is composed of a metal material and has a mass of from 5 grams to 20 grams. The internal tube is disposed within the hollow interior of the body. The internal tube is composed of a metal material and has a mass of from 5 to 15 grams.

[0026] Yet another aspect of the present invention is a golf club head including a face component, a crown component and a sole component. The face component is composed of a plurality of pre-preg plies. The face component has a striking plate portion and a return portion. The return portion extends laterally rearward from a perimeter of the striking plate. The striking plate portion has a thickness in the range of 0.050 inch to 0.250 inch. The plurality of plies of the face component include a plurality of face doubler plies in a ninety degree orientation, a plurality of face doubler plies in a zero degree orientation, a plurality of full face plies in a positive forty-five degree orientation, a plurality of full face plies in a negative forty-five degree orientation, and a plurality of full face plies in a zero degree orientation. The crown component is attached to an upper section of the return portion of the face component. The sole component has a ribbon portion and a bottom portion. The bottom portion of the sole component is attached to a lower section of the return portion of the face component and the ribbon portion of the sole component is attached to the crown component.

[0027] Yet another aspect of the present invention is a golf club including a golf club head, a shaft and a grip. The golf club head has a volume of 275 cubic centimeters to 600 cubic centimeters. The shaft has a tip end and a butt end, and is composed of a graphite material. The tip end of the shaft is attached to the golf club head. The grip is placed over a butt end of the shaft. The golf club has a mass less than 290 grams, and the golf club head has a coefficient of restitution ranging from 0.80 to 0.93 under standard USGA conditions.

[0028] Yet another aspect of the present invention is a golf club head including a face component, a crown and a sole. The face component is composed of a plurality of pre-preg plies ranging from 20 to 70 plies. The face component has a striking plate portion and a return portion. The return portion extends laterally rearward from a perimeter of the striking plate. The striking plate portion has a thickness in the range of 0.050 inch to 0.250 inch. The crown is composed of a plurality of pre-preg plies ranging from 3 to 20 plies. The crown is attached to the face component and overlaps an upper section of the return portion. The upper section of the return portion extends rearward from the perimeter of the striking plate portion a distance of at least 0.5 inch. The sole component is composed of a plurality of pre-preg plies ranging from 3 to 20 plies. The sole component has a ribbon portion and a bottom portion. The bottom portion of the sole component is attached to a lower section of the return portion of the face component and the ribbon portion of the sole component is attached to the crown component. The lower section of the return portion extends rearward from the perimeter of the striking plate portion a distance of at least 0.5 inch. The golf club head has a coefficient of restitution ranging from 0.80 to 0.93 under standard USGA conditions.

[0029] Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

[0030] FIG. 1 is an exploded view of a golf club head of the present invention.

[0031] FIG. 2 is a front view of a golf club head of the present invention.

[0032] FIG. 2A is a front view of a golf club head of the present invention illustrating the aspect ratio of the golf club head.

[0033] FIG. 2B is a view of a golf club with attached shaft and grip of the present invention.

[0034] FIG. 3 is a top plan view of a golf club head of the present invention.

[0035] FIG. 4 is a heel end view of a golf club head of the present invention.

[0036] FIG. 5 is a toe end view of a golf club head of the present invention.

[0037] FIG. 6 is a bottom plan view of a golf club head of the present invention.

[0038] FIG. 7 is a cross-sectional view of the golf club head of FIG. 3 along line 7—7.

[0039] FIG. 8 is a cross-sectional view of the golf club head of FIG. 2 along line 8—8.

[0040] FIG. 9 is an isolated cross-section view of a face preform of a golf club head of the present invention.

[0041] FIG. 9A is an enlarged view of area A of FIG. 9.

[0042] FIG. 9B is an enlarged view of area B of FIG. 9;

[0043] FIG. 10 is an isolated cross-section view of a crown/face preform of a golf club head of the present invention.

[0044] FIG. 11 is an isolated cross-section view of a sole preform of a golf club head of the present invention.

[0045] FIG. 12 is a top plan view of a golf club head of the present invention illustrating the variation in thickness of the walls of the golf club head.

[0046] FIG. 13 is a front plan view of a golf club head of the present invention illustrating the variation in thickness of the walls of the golf club head.

[0047] FIG. 14 is a bottom plan view of a golf club head of the present invention illustrating the variation in thickness of the walls of the golf club head.

[0048] FIG. 15 is a heel end view of a golf club head of the present invention illustrating the variation in thickness of the walls of the golf club head.

[0049] FIG. 16 is a plan view of a face/crown ply having a ninety degree orientation.

[0050] FIG. 17 is a plan view of a full face ply having a ninety degree orientation.

[0051] FIG. 18 is a plan view of a face doubler ply having a ninety degree orientation.

[0052] FIG. 19 is a plan view of a sole ply having a negative forty-five degree orientation.

[0053] The present invention is directed at a golf club that has a large volume and a minimum mass. The golf club has a golf club head that is composed of a plurality of plies of pre-preg material, a lightweight graphite shaft and a lightweight grip. The golf club head is forgiving and has a high coefficient of restitution thereby enabling for less dispersion and greater distance of a golf ball hit with the golf club of the present invention.

[0054] As shown in FIGS. 1-6, a golf club head of the present invention is generally designated 20. The club head 20 is either a fairway wood or a driver. The drivers range in loft angle of from six degrees to fifteen degrees. The club head 20 has a body 22 that is generally composed of a composite material such as plies of carbon pre-preg sheets. The body 22 has a crown 24, a striking plate 26, a sole 28 with a bottom portion 28aand a ribbon 30.The ribbon preferably has an upper ribbon wall 30aand a lower ribbon wall 30b. The ribbon 30 generally extends from a toe end 32 to a heel end 34.The ribbon 30 generally begins at one end of the striking plate 26 and ends at an opposite end of the striking plate 26. A rear 36 of the body 22 is opposite the striking plate 26 and is defined by portions of the ribbon 30, the crown 24 and the sole 28. Also, at the heel end 34 of the club head 20 is an internal tube 38 with an opening 39 for placement of a shaft therein. The internal tube 38 is placed within the hollow interior 44 of the body 22. Within the ribbon is a weight member 40.

[0055] A sole plate 42 is disposed within a recess 29 of the bottom portion 28a of the sole 28. The sole plate 42 is preferably composed of a metal material such as aluminum or titanium, and preferably has a mass of 5 grams to 20 grams. A preferred mass for an aluminum sole plate 42 is approximately 11 grams, and a preferred mass for a titanium sole plate 42 is approximately 18 grams. The sole plate 42 is preferably bonded within the recess 29 through use of adhesives. The sole plate 42 preferably has embossed graphics thereon. The sole plate 42 increases the durability of the club head 20 since the sole 28 often impacts the ground during the striking of a golf ball.

[0056] The club head 20 of the present invention also has a greater volume than a composite club head of the prior art while maintaining a weight that is substantially lower or equivalent to that of the prior art. The volume of the club head 20 of the present invention ranges from 175 cubic centimeters to 600 cubic centimeters, more preferably ranges from 300 cubic centimeters to 450 cubic centimeters, and is most preferably 360 cubic centimeters for a driver. The mass of the club head 20 of the present invention ranges from 165 grams to 300 grams, preferably ranges from 175 grams to 225 grams, and most preferably from 188 grams to 195 grams. The body 22 of plies of pre-preg material has a mass ranging from 80 grams to 150 grams, and most preferably 98 grams.

[0057] The volume of the present invention is increased by increasing the vertical distance of the club head 20 from the sole 28 to the crown 24, as opposed to the horizontal distance of the heel end 34 to the toe end 32. This increase in volume is brought about by the dual wall structure of the ribbon 30. The upper ribbon wall 30ais approximately perpendicular relative to the crown 24, while the lower ribbon wall 30bpreferably has angle between 25 degrees to 75 degrees relative to the crown 24. The greater volume of the club head 20 allows the club head 20 to be more forgiving than prior art golf club heads while providing better performance. The mass of club head 20 is much less than metal club heads of similar volumes, and allows the use of more discretionary mass to optimize mass properties.

[0058] The striking plate 26 has a smaller aspect ratio than striking plate plates of the prior art. The aspect ratio as used herein is defined as the width, “w”, of the striking plate divided by the height, “h”, of the striking plate 26, as shown in FIG. 2A. In one embodiment, the width w is 90 millimeters and the height h is 54 millimeters giving an aspect ratio of 1.666. In conventional golf club heads, the aspect ratio is usually much greater than 1. For example, the original GREAT BIG BERTHA® driver had an aspect ratio of 1.9. The aspect ratio of the present invention preferably ranges from 1.0 to 1.7.

[0059] As shown in FIG. 7, the internal tube 38 lies within the hollow interior 44 of the club head 20. The internal tube is preferably composed of a metal material and has a mass ranging from 8 grams to 20 grams. The internal tube 38 is most preferably composed of stainless steel and has a mass of approximately 14 grams. The internal tubing 38 has a bore 130 to receive an insert and a shaft, not shown, therein. Such an insert is discussed in U.S. Pat. No. 6,352,482 for a golf Club With Hosel Liner, which is hereby incorporated by reference in its entirety, Preferably, the club head 20 has a hollow interior 44 defined by the body 22, however, the light weight of the composite body 22 allows for numerous manipulations in placement of weight, foam, sound enhancing devices and the like within the hollow interior 44.

[0060] Referring specifically to FIG. 1, the club head 20 has a weight member 40 disposed within the plies of pre-preg that compose the ribbon 30 of the club head 20. Preferably, the weight member 40 is composed of three weight members 40a, 40band 40c. One such weight member 40 is described in U.S. Pat. No. 6,386,990, entitled A Composite Golf Club Head With An Integral Weight Strip, which is hereby incorporated by reference in its entirety. Another such method is described in co-pending U.S. patent application Ser. No. 09/947,292, for Internal Weighting For A Composite Golf Club Head, filed on Sep. 5, 2001, and hereby incorporated by reference in its entirety. The weight member 40 has a mass ranging from 30 grams to 80 grams, more preferably 45 grams to 70 grams, and most preferably 54 grams. The weight member 40 is preferably composed of a metal material integrated into a polymer medium. The metal material is preferably selected from copper, tungsten, steel, aluminum, tin, silver, gold, platinum, or the like. A preferred metal is tungsten . The weight member 40 has a density greater than the composite material of the body 22. Preferably, the weight member 40 extends from approximately the heel end 34 of the striking plate 26 through the rear 36 to the toe end 32 of the striking plate 26. However, the weight member 40 may only extend along the rear 36 of the ribbon 30, the heel end 34 of the ribbon 30, the toe end 32 of the ribbon 30, or any combination thereof Those skilled in the pertinent art will recognize that other weighting materials may be utilized without departing from the scope and spirit of the present invention.

[0061] The placement of the weighting members 40a-callows for the moment of inertia of the golf club head 20 to be optimized. A more thorough description of the optimization of the moments of inertia is disclosed in co-pending U.S. patent application Ser. No. 09/796,951, filed on Feb. 27, 2001, entitled High Moment of Inertia Composite Golf Club, and hereby incorporated by reference in its entirety. In one preferred example of the golf club head 20 of the present invention, the moment of inertia about the Ixx axis through the center of gravity is approximately 2566 grams-centimeters squared (“g-cm²”), the moment of inertia about the Iyy axis through the center of gravity is approximately 1895 g-cm², and the moment of inertia about the Izz axis through the center of gravity is approximately 3368 g-cm².

[0062] As shown in FIGS. 8, 9, 9A and 9B, a return portion 100 is a transition area from a perimeter 29 of the striking plate 26 rearward towards the crown 24. The return portion 100 has a thickness ranging from 0.070 inch to 0.200 inch to control the compliance of the striking plate 26. The return portion 100 has an upper section 100a, a lower section 100b, a heel section 100c, not shown, and a toe section 100d, not shown. The return portion 100 also has a taper region 101, which includes an upper tapering region 101a, a lower tapering region 101b, a heel tapering region 101c, not shown, and a toe tapering region 101d, not shown. The tapering region 101 tapers in thickness from a greater thickness nearer the striking plate portion 26 to a lesser thickness rearward toward the crown 24.

[0063] The return portion 100 has a predetermined length, which extends rearward from the perimeter 29 of the striking plate portion 26 into the crown 24. Preferably, the distance of the return portion 100, Dr, ranges from 0.25 inch to 2.0 inches, more preferably from 0.5 inch to 1.75 inches, and most preferably 1.5 inches. Preferably, the distance from the perimeter 29 to the beginning of the tapering region 101 of the return portion 100 ranges from 0.25 inch to 1.5 inches, and most preferably 1.0 inch.

[0064] The body 22 manufactured from a face component 125, which includes the striking plate portion 26 and the return portion 100, a crown component 124 and a sole component 128. The crown component 124 overlaps the face component 125, as shown in FIG. 10. The sole component 128 includes the ribbon portion 30 and the bottom portion 28a. The sole component 128 is attached to the crown component 124 and the face component 125.

[0065] FIGS. 16-19 illustrates preferred pre-preg sheets for forming the composite body of the golf club head 20. FIG. 16 illustrates a face/crown ply pre-preg sheet that is generally designated 55. The face/crown ply 55 has a plurality of fibers 51 dispersed within a resin body 53. The fibers 51 are preferably composed of a carbon material. Alternatively, the fibers 51 may be aramid fibers, glass fibers or the like. The resin is typically an epoxy material. The relation of the fibers 51 to the striking plate 26, when the striking plate 26 is in a position to strike a golf ball, determines the orientation of the fibers 51. If the fibers 51 are parallel with the ground, or in other words extending across from the toe end to the heel end, then the face/crown ply 55 has a zero degree orientation. If the fibers 51 are approximately perpendicular to the ground, as shown in FIG. 16, or in other words extending from the crown to the sole, then the face/crown ply 55 has a ninety degrees orientation.

[0066] FIG. 17 illustrates a full face ply pre-preg sheet that is generally designated 57. As with the face/crown ply 55, the full face ply 57 has a plurality of fibers 51 dispersed within a resin body 53. The fibers 51 extend from the sole 28 to the crown 24, and thus the full face ply 57 has fibers 51 that are perpendicular to the ground when it is in a position for striking a golf ball. Therefore, the full face ply 57 of FIG. 17 has a ninety degrees orientation.

[0067] FIG. 18 illustrates a face doubler ply pre-preg sheet that is generally designated 58. As with the face/crown ply 55, the face doubler ply 58 has a plurality of fibers 51 dispersed within a resin body 53. The fibers 51 extend from the sole 28 to the crown 24, and thus the face doubler ply 58 has fibers 51 that are perpendicular to the ground when it is in a position for striking a golf ball. Therefore, the face doubler ply 58 of FIG. 18 has a ninety degrees orientation.

[0068] FIG. 19 illustrates a sole ply pre-preg sheet that is generally designated 59. As with the face/crown ply 55, the sole ply 59 has a plurality of fibers 51 dispersed within a resin body 53. The fibers 51 extend at a forty-five degree angle relative to the ground when it is in a position for striking a golf ball. Therefore, the sole ply 59 of FIG. 19 has a forty-five degree orientation.

[0069] As previously stated, the preferred composite material is plies of carbon pre-peg sheets. Plies of pre-preg composite sheets are manufactured by pulling strands of fiber in a parallel motion, preferably carbon, aramid or glass fiber, through a resin film and allowing the resin to partially cure or “stage”. When the resin is partially staged, the resin holds the fibers together such that the fibers form a malleable sheet with all of the fibers in a specific orientation relative to an edge of the sheet. Preferred orientations are zero degrees, plus forty-five degrees, minus forty-five degrees and ninety degrees. Exemplary carbon pre-preg fiber sheets may be obtained from Newport Composites of Santa Ana, California, Fiberite Inc. of Greenville, Texas, or Hexcel Inc. of Pleasonton, California.

[0070] The manipulation of the thickness of the various regions of the body 22 allows the golf club head 22 to have superior durability, forgiveness and performance as compared to prior art composite golf club heads. As shown in FIGS. 12-15, the thickness of the body 22 is focused on the striking plate portion 26. In a most preferred example: the region designated A of the striking plate portion 26 has a thickness of approximately 0.169 inch; the region designated B, at the junction of the crown 24 and striking plate 26 has a thickness of approximately 0.188 inch; the region designated C of the bottom portion 28aof the sole 28 has a thickness of approximately 0.221 inch; the region designated D of the ribbon 30 and of the bottom portion 28ahas a thickness of approximately 0.202 inch; the region designated E of the crown 24, the bottom portion 28aand the ribbon 30 has a thickness of approximately 0.033 inch; and the region designated F of the crown 24 has a thickness of approximately 0.191 inch. The regions designated Z1, Z2, Z3, Z4, Z5 and Z6 are tapering zones where the thickness tapers rearward.

[0071] The golf club head 20 is preferably manufactured using a bladder molding process. One such process is described in U.S. Pat. No. 6,248,025, which is hereby incorporated by reference. However, those skilled in the pertinent art will recognize that other manufacturing methods may be utilized without departing from the scope and spirit of the present invention.

[0072] The coefficient of restitution of the club head 20 of the present invention under standard USGA test conditions with a given ball ranges from 0.8 to 0.9, preferably ranges from 0.81 to 0.87 and is most preferably 0.82.The coefficient of restitution (also referred to herein as “COR”) is determined by the following equation: $e=\frac{v_2-v_1}{\stackrel{\_}{U_1}-\stackrel{\_}{U_2}}$

[0073] wherein U₁is the club head velocity prior to impact; U₂is the golf ball velocity prior to impact which is zero; v₁is the club head velocity just after separation of the golf ball from the striking plate of the club head; v₂is the golf ball velocity just after separation of the golf ball from the striking plate of the club head; and e is the coefficient of restitution between the golf ball and the club striking plate.

[0074] The values of e are limited between zero and 1.0 for systems with no energy addition. The coefficient of restitution, e, for a material such as a soft clay or putty would be near zero, while for a perfectly elastic material, where no energy is lost as a result of deformation, the value of e would be 1.0.The thickness of the striking plate 26 and the orientation of the plies of pre- preg determine the coefficient of restitution of the golf club head 20. Additionally, the thickness of the return 100 of the golf club head 20 allows for a greater deflection in the striking plate 26 which increases the coefficient of restitution of the golf club head 20. The return 100 couples the striking plate 26 to the crown 24 which reduces the loss of energy to the striking plate 26 during impact with a golf ball. If the return 100 is too thick, the striking plate 26 is isolated and rigid, thereby reducing the coefficient of restitution. If the return 100 is too thin, failure of the striking plate 26 may occur upon impact with a golf ball.

[0075] From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims: