2. Brief Description of the Related Art As is well known in the game of golf, wood-type golf clubs are used when it is desired to strike a golf ball as far as possible. A 1 wood, commonly referred to as a driver, is generally used to strike the golf ball from a tee, while a 2,3,4, or 5 wood is used when the golf ball is struck from a fairway. Traditionally, wood-type golf club heads were formed of wood; however, the recent trend is to form these heads from metals, including titanium. One notably advantage of using metals to form the wood-type golf clubs is that the physical characteristics, such as weight, density, and hardness, may be more easily controlled when metals are used to form the golf club head.

There has been an increasing effort to produce a wood-type golf club head which transfers maximum energy into the golf ball at the instant of striking the golf ball. One way to accomplish this is to reduce the drag of the golf club head to thereby increasing golf club speed resulting in a more optimum energy transfer.

Other factors which have been investigated in attempting to maximize the energy transfer include the face hardness, center of gravity position, hosel length, shaft stiffness and length.

Many conventional wood-type golf clubs, particularly drivers, have smooth bottoms or sole surfaces. With conventional wood-type golf club heads, a portion of the club sole often engages the ground surface during the execution of a shot, causing the club head to decelerate considerably and to torque, or turn because of the ground resistance encountered. This is particularly true when a ball is lying in a less than ideal position, such as a divot depression, rough, heavy grass, hard or rocky ground, a sand trap or other naturally occurring areas other than a closely cut fairway.

When these wood-type golf clubs are used in the fairway and ground contact is made behind the ball, the club head can bounce upward causing the ball to be "skulled"or"bladed", producing disastrous results. It is generally known to reduce the contact area of the sole surface of the wood-type golf club head to thereby prevent the golf club head from bouncing up on the ground and at the same time the central portion of the sole surface is left as it is to thereby prevent the golf club head from striking too deeply into the ground.

When a golfer strikes the golf ball, the ball is flattened out against the face of the club. Thereafter, due to elasticity, the ball begins to resume its round shape, thus propelling itself in a direction very nearly normal to the club face (assuming no spin about a vertical axis of the ball). However, the swing of the golf club should not stop when the ball leaves the club face. It is well known that a golfer perfects his or her swing by following through smoothly after impact between the striking surface of the golf club and the golf ball. It would be desirable to provide a wood-type golf club head having a configuration which facilitates the"follow through"without detracting from the performance of the club in other respects, particularly the correlated bounce effect when it is provided. As previously noted, the elasticity of the ball propels it in a direction that is nearly normal to the striking face, but not

quite because at the moment of impact, the golf club head is cutting across a line in the direction of the intended line of flight, i. e., across a line on the ground in a direction normal to the club head at the moment of impact, assuming a stroke with the face of the club square and not"open"or"closed". The face of the club is referred to being"open"when it is turned clockwise by a right handed golfer at the moment of impact as the player swings the club. A"closed"face occurs when the face of the club is turned counterclockwise by a right handed golfer as the player strokes the ball. When the face of the club head is"open", the ball will hook when the player makes contact with the ball and a"closed"face will result in the ball being sliced when the club head makes contact with the ball. The club head cuts across the other side of that line relative to the golfer to the near side of the line. The fact that the club head is cutting across can be verified by observing the sole of any golf club that has been extensively used by a consistent golfer. It will be marked with scratch lines that are off from a direction normal to the club face by a small angle. It would be desirable to provide a configuration for the sole, toe and heel portions of the club head which will facilitate the follow through and allow a golfer to cleanly approach a golf ball during the golfer's stroke so that the striking face surface cleanly contacts the golf ball resulting in an accurate shot.

Summarv of the Invention In one aspect, the present invention relates to an wood-type golf club head having an improved sole configuration which reduces ground resistance between the sole and a playing surface. In a preferred embodiment, the sole configuration comprises a central planar surface and a plurality of side cambered surfaces beveled toward the central planar surface. The central planar surface is preferably centrally aligned in relation to a striking surface of the golf club head so that ground contact with the central planar surface during a swinging motion leads to a centered shot. In addition, a forward cambered surface extends from a bottom edge of the striking surface to the central planar surface and the plurality of side cambered surfaces

disposed on both sides of the central planar surface. The plurality of side cambered surfaces, central planar surface, and forward cambered surface are preferably formed of metal and are raised in relation to a bottom surface of the golf club head. In one exemplary and preferred embodiments, the central planar surface and the plurality of side cambered surfaces are generally tapered toward one end where the surfaces generally converge to a point. In other words, at the end opposite the convergence point, the central planar surface and the plurality of side cambered surfaces have a greater width than at the opposite end proximate the convergence point.

In one preferred and exemplary embodiment, the pair of side cambered surfaces immediately adjacent to the central planar surface on either side thereof have a first planar surface formed at one end proximate the forward cambered surface and a second planar surface formed at an opposite end, wherein the second planar surface is beveled with respect to the first planar surface. Moreover, in this embodiment, the central planar surface actually comprises a first central planar surface at one end proximate the forward cambered surface and a second planar surface at an opposite end, wherein the second central planar surface is beveled with respect to the first central planar surface.

In another aspect of the present invention, a rear perimeter weight band is disposed in the rear face of the golf club head. This rear perimeter weight band is preferably in the form of a tapered raised band extending in the heel-to-toe direction of the golf club head, wherein the width of the rear perimeter weight band is greater toward the toe than at the heel. Furthermore, the rear perimeter weight band also is slightly raised in relation to the rear face so that additional mass is provided toward the rear of the golf club head. This results in improved center of gravity and greater stability on off-center hits of the golf ball.

Using a golf club head having the improved sole configuration of the present invention on a normal grass surface, such as a fairway of a golf course, the sole configuration prevents the club head from penetrating too deeply into the grass turf when the golfer strikes the ground during a swing and thereby prevents undue

resistance between the golf club head and the ground surface. This undue resistance will reduce the golf club head speed and will cause the golf club head to torque during the execution of the swing. When the golf club head torques as the golfer swings and makes contact with the golf ball, an undesirable shot will likely result because the face of the golf club will be"open"or"closed". When the golf club head is"open"at the moment of impact, the ball will hook and in contrast, when the golf club head is"closed", the ball will slice. The sole configuration of the present invention is designed so that if ground contact is made during a swinging motion, the planar surface of the sole contacts the ground surface and permits the golf club head to ride along the ground surface without the sole portion digging into the ground surface during a shot in which ground contact is made. The forward cambered surface of the golf club head of the present invention also prevents the leading edge of the striking surface from either bouncing or digging too deeply into the ground thereby minimizing the lateral movement of the golf club head. Thus, the sole configuration of the present invention facilitates a smooth, centered shot by the golfer by reducing ground resistance.

The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.

Brief Description of the Drawings For the purpose of illustrating the invention, there are shown in the drawing forms which are presently preferred; it being understood, however that this invention is not limited to the precise arrangements and instrumentalities shown. Referring now to the drawings wherein like elements are numbered alike in the several FIGURES: FIGURE 1 is a perspective view of a golf club in accordance with the present invention;

FIGURE 2 is left side view of an exemplary golf club head in accordance with the present invention; FIGURE 3 is a front elevation view of the golf club head of FIGURE 2; FIGURE 4 is a bottom plan view of the golf club head of FIGURE 2; FIGURE 5 is a right side view of the golf club head of FIGURE 2; FIGURE 6 is a rear elevation view of the golf club head of FIGURE 2; FIGURE 7 is a front elevation view of a second embodiment of the golf club head of FIGURE 2 further including a plurality of hard particles disposed on a striking surface thereof ; FIGURE 8 is a front elevation view of a third embodiment of the golf club head of FIGURE 2 further including a polymeric insert formed in the striking surface thereof; and FIGURE 9 is a bottom plan view of a third embodiment of the present invention.

Detailed Description of the Invention The present invention represents an improvement over conventional wood- type golf clubs which have a relatively smooth sole or bottom surface, particularly in the heel-to-toe direction. When a golfer uses these conventional wood-type golf clubs and swings so as to strike the golf ball, the sole portion of the club head likely makes some contact with the ground behind the golf ball as the golfer follows through and drives the ball. Often when a wood-type golf club makes ground contact behind the ball, a so-called"fat"shot typically results. Furthermore, the golf club head can bounce upwardly causing the ball to be"skulled"or"bladed,"which consequently produces an undesired shot. The chances of an undesireable shot greatly increase when the golf club head makes contact with the ground because of the ground resistance on the golf club head. With the wood-type golf club heads of the present invention, the occurrence of these undesirable shots is alleviated or

eliminated by the improved sole configuration of the present invention which reduces ground resistance.

FIGURES 1-6 show an exemplary and preferred embodiment of a golf club head 10 in accordance with the present invention. Golf club head 10 includes a top surface 12, a sole (bottom surface) 14 disposed opposite to the top surface 12, a hosel 16 which is designed to interfit with a shaft main body 17 (shown in FIGURE 1), a heel 18 which is the portion of golf club head 10 where sole 14 meets hosel 16, a toe 20 opposite to heel 18, a ball striking face surface 22 serving as a striking surface and located between heel 18 and toe 20 and a rear surface 24 located opposite to the ball striking face surface 22 between heel 18 and toe 20 wherein rear surface 24 continues from sole 14. Hosel 16 forms a part of heel 18 so that hosel 16 may be connected to the club shaft 17 and ball striking face surface 22 includes a plurality of score lines 26 which improve play performance of a golf ball when a player strikes the golf ball with golf club head 10 of the present invention. Ball striking face surface 22 has a lowermost edge 28 and rear surface 24 includes a trailing edge 30 located between heel 18 and toe 20. Trailing edge 30 is formed by the intersection of sole 14 and rear surface 24 and leading edge 28 is formed by the intersection of a forward cambered surface 29 of sole 14 and ball striking face surface 22. In an exemplary embodiment, ball striking surface 22 has a thickness of about. 110 to about. 135 inches. In addition, in one aspect of the invention, top surface 12, also referred to as the crown portion of golf club head 10 has a thickness greater than many conventional club heads. In an exemplary embodiment, improved crown rigidity is achieved by having a crown wall thickness (thickness of top surface 12) of about. 050 inches or greater.

In accordance with the present invention, sole 14 comprises forward cambered surface 29, a bottom surface 31, a central planar surface 32 and a plurality of first side cambered surfaces 34 and a plurality of second side cambered surfaces 36. Forward cambered surface 29, central planar surface 32, and the plurality of first and second side cambered surfaces 34 and 36 are raised in relation to bottom surface

31. In an exemplary and preferred embodiment, first side cambered surfaces 34 are disposed adjacent central planar surface 32 and extend from forward cambered surface 29 toward trailing edge 30 of rear surface 24. Second side cambered surfaces 36 are disposed adjacent first side cambered surfaces 34 and extend from forward cambered surface 29 toward trailing edge 30 of rear surface 24. In the illustrated embodiment best shown in FIGURE 4, central planar surface 32 is intermediate a pair of first side cambered surfaces 34 and one of a pair of second side cambered surfaces 36 is disposed adjacent one of the pair of first side cambered surfaces 34.

The central planar surface 32, pair of first side cambered surfaces 34, and pair of second side cambered surfaces 36 are preferably tapered so that an end of each surface 32,34, and 36, which intersects forward cambered surface 34, has a width greater than a width of an opposite end of each of surfaces 32,34, and 36, which is proximate trailing edge 30 of rear surface 24. More specifically, central planar surface 32 has a first end 40 which intersects forward cambered surface 29 and the pair of first side cambered surfaces 34 and the pair of second side cambered surfaces 36 have first ends 42 and 44, respectively, which intersect forward cambered surface 29. An opposite second end 46 of central planar surface 32 and opposite second ends 48 and 50 of the pairs of first and second side cambered surfaces 34 and 36, respectively, converge to a point 52 proximate trailing edge 30 of rear surface 24.

In accordance with the present invention, the pair of first side cambered surfaces 34, the pair of second side cambered surfaces 36, and forward cambered surface 29 are all beveled in relation to central planar surface 32. In the exemplary and illustrated embodiment, central planar surface 32 actually comprises a first central planar surface 54 which includes first end 40 and a second central planar surface 56 which includes second end 46. Second central planar surface 56 is beveled in relation to first central planar surface 54 and second central planar surface 56 preferably is triangular shaped. Similarly, the pair of first side cambered surfaces

34 comprise first planar portions 60 which intersect forward cambered surface 29 and second planar portions 62 which converge to point 52. Second planar portions 62 preferably are triangular in shape. Second planar portions 62 are beveled with respect to first planar portions 60.

As shown best in FIGURE 3, a sole plane S is shown and generally is defined as the plane having first central planar surface 54 (not shown) disposed therein. First planar portions 60 of first side cambered surfaces 34 are inclined at an angle A with respect to sole plane S. The pair of second side cambered surfaces 36 are inclined at an angle B with respect to sole plane S, wherein angle B is greater than angle A. Angle A is preferably from about 45° to about 60° and more preferably about 53-55°. Angle B is preferably from about 8° to about 20° and more preferably is about 11-13°.

As shown in FIGURE 3, first planar portions 60 (not numbered) of first side cambered surfaces 34 are angled, as measured by angle A, above the ground surface (in this FIGURE, ground surface and sole plane S are coincident) so that when a golfer takes a stroke at a golf ball and properly positions golf club head 10 causing central planar surface 32 to make contact with the ground surface as the golfer follows through with the shot thereby causing ball striking face surface 22 to make clean contact with the golf ball, the ball is propelled toward a target. Because first side cambered surfaces 34 are angled in relation to central planar surface 32, a self- centering mechanism is provided. For example, when a golfer makes an off- centered swinging motion in which one of the first side cambered surfaces 34 makes contact with the ground, the beveled nature of first side cambered surface 34 increases the ability of sole 14 to ride along the ground and center upon central planar surface 32 so that a smooth centered shot results.

Second side cambered surfaces 36 also act to mitigate the effects of off- centered and more particularly, heel and toe shots. As shown in FIGURE 3, second side cambered surfaces 36 are angled, as measured by angle B, above the ground surface (in this FIGURE, ground surface and sole plane S are coincident) so that in

the instance that the golfer does not squarely address the golf ball, the beveled nature of second side cambered surfaces 36 act to increase the chances of making a recovery of the off-centered swing to produce a more centered shot. For example, if the golfer makes an off-centered shot, e. g, a heel or toe shot, in which one of second side cambered surfaces 36 makes contact with the ground, the beveled nature of second side cambered surface 36 will increase the ability to center golf club head 10 toward central planar surface 32 due to second side cambered surface 36 being angled toward central planar surface 32.

In addition, forward cambered surface 29 of sole 14 acts to mitigate the effects of a shot in which the golfer strikes the ground during a swinging motion.

The beveled nature of forward cambered surface 29 advantageously permits golf club head 10 to ride along the ground smoothly and thereby, the resistance between golf club head 10 and the ground during such a shot is reduced by the present invention. This also increases the likelihood that such contact with the ground will not adversely impact the shot of the golfer as conventionally happens when a leading edge of a golf club head digs into the ground during a shot approach. As best shown in FIGURE 4, the intersection of forward cambered surface 29 with central planar surface 29, the pair of first side cambered surfaces 34 and the pair of second side cambered surfaces 36 is not a straight edge but rather comprises a series of arcuate curves.

The angled transitions between all of the beveled surfaces of forward cambered surface 29, central planar surface 32, the pair of first side cambered surfaces 34, and the pair of second side cambered surfaces 36 results in a smooth raised member which extends below and from bottom surface 31 of sole 14. This results in the improved sole 14 of the present invention which increases the likelihood that a centered shot will result during the golfer's swing when contact is made between golf club head 10 and the ground due to a decrease in mass forming sole 14 which results in a decrease in ground resistance between golf club head 10 and the ground. As best shown in FIGURE 4, in total, these surfaces form the shape

of a diamond. It being understood that this diamond shape is merely exemplary in nature and not limiting of the present invention.

In other words, when striking a golf ball, the golf club head 10 of the present invention is designed so that central planar surface 32 of sole 14 contacts the ground surface and permits golf club head 10 to ride along the ground surface without sole 14 digging into the ground surface, ensuring that optimum contact is made with the ball, thereby ensuring maximum energy transfer. Importantly, the improved sole configuration 14 on the present invention substantially alleviates or eliminates the impact of off-centered shots because of the presence of forward cambered surface 29 and first and second side cambered surfaces 34 and 36.

By having first and second side cambered surfaces 34 and 36, forward cambered surface 29, and central planar surface 32 for contacting and riding along the ground surface, the configuration of sole 14 of golf club head 10 minimizes the negative effects that would occur with conventional golf clubs having a smooth sole wherein the club head digs or snags into the ground surface, especially when an off- centered stroke is made and the golf ball is not squarely hit. Accordingly, sole 14 incorporates a corrective action for the off-centered shot, whereby the design of sole 14 increases the likelihood that a centered shot will result during an off-centered shot approach.

As shown in FIGURE 1, a shaft 17 is rigidly attached to hosel 16 as an extension thereof in the usual manner. A preferred golf club shaft 17 is a wide-body (fat) shaft formed of graphite and polyamide fibers (KEVLAR by Dupont) disclosed in commonly owned U. S. Patent Application No. 60/117213 filed on January 25, 1999, which is hereby incorporated in its entirety. This graphite/kevlar composite shaft 17 offers an elastic shaft which stores and releases more energy than conventional shafts formed of steel or graphite. Shaft 17 preferably has a non- tapered configuration having a wider diameter than conventional shafts. For example, in the preferred embodiment, shaft 17 has a diameter of about. 55 inches to about. 70 inches and preferably about. 60 inches. A wider tip at the point of

connection between golf club head 10 and shaft 17 provides more stability at impact while retaining flexibility. In other words, the degree of torque of shaft 17 is better controlled. In accordance with the present invention and as best shown in FIGURE 3, hosel 16 has a wide hosel design with a short length. This results in better heel- to-toe weighting and enhanced forgiveness on golf balls hit near heel 18. In the exemplary embodiment shown in FIGURE 3, hosel has a length L of about 1.40 and a width (hosel bore) W of about. 530 inches. It being understood that these dimensions are recited for purpose of illustration and it is within the scope of the present invention that other dimensions are suitable for use in fabricating hosel 16.

In yet another aspect of the present invention, a rear perimeter weight band 90 is formed in rear surface 24 of golf club head 10. This particular feature of golf club head 10 is best illustrated in FIGURES 2,4, and 6 and results in golf club head 10 having a more ideal center of gravity and greater stability on off-center hits. Rear perimeter weight band 90 preferably comprises a metal band which extends outwardly from the surface of rear surface 24 and extends between heel 18 and toe 20. In an exemplary embodiment, rear perimeter weight band 90 is about 1.5 mm thicker than the rest of rear surface 24, resulting in approximately 10% more mass allocation where it is needed most, namely rear surface 24. Because a substantial portion of the mass of the improved sole 14 of the present invention is forwardly positioned toward ball striking face surface 22, the addition of mass to rear surface 24 results in better weight balance in golf club head 10. Rear perimeter weight band 90 is tapered so that a first end 92 proximate heel 18 has width greater than the width of an opposite second end 94 proximate toe 20. In other words, the width of rear perimeter weight band 90 progressively increases in the heel-to-toe direction.

This also results in improved weight distribution of golf club head 10 because rear perimeter weight band 90 distributes weight in a non-even manner due to the tapered design. Because the center of gravity of central planar surface 32, the pair of first side cambered surfaces 34 and the pair of second side cambered surfaces 36 is

located slightly more toward heel 18, the progressively increasing width of rear perimeter weight band 90 in the opposite direction toward toe 20 results in increased weight balance in golf club head 10. Accordingly, rear perimeter weight band 90 produces a deeper center of gravity for achieving a larger moment of inertia. In addition, rear perimeter weight band 90 reduces the torque of golf club head 10 during the swinging motion and impact with the golf ball. Rear perimeter weight band 90 may be formed of the same material as golf club head 10 or may be formed of different material. In a preferred embodiment, rear perimeter weight band 90 is formed of titanium or a titanium alloy.

In an exemplary embodiment and as best shown in FIGURE 3, the center of gravity (CG) of golf club head 10 has a height and a depth determined by its location in golf club head 10. The height of the center of gravity is approximately. 850 inches relative to and measured from sole plane (S). The depth of the center of gravity is approximately 1.380 inches relative to ball striking face surface 22. In the exemplary embodiment, the center of gravity does not fall directly on the center line (toe 20 to heel 18 direction) of golf club head 10 but rather is located slightly off from the center line in a direction away from hosel 16. More specifically, the center of gravity is located about. 08 inches from the center line of golf club head 10.

The loft angle C of golf club head 10 is measured as shown in FIGURE 5 from a vertical plane V to a plane F of ball striking face surface 22, wherein edge 28 is disposed in vertical plane V. Loft angle C varies according to the type of golf club head 10 that is being used, e. g., 1 wood or a 5 wood, and may differ among the golf club manufacturers by a few degrees. Typically, for wood-type golf club heads, the loft angle C is from about 7° to about 12°.

In a preferred and exemplary embodiment, golf club head 10 is formed of metal and more preferably is formed of titanium or a titanium alloy. However it is within the scope of the present invention that other materials may be used to form golf club head 10. Turning to FIGURE 7, illustrating a second embodiment of the present invention, ball striking face surface 22 includes a plurality of hard particles

100 disposed thereon. Preferably, the plurality of hard particles 100 comprises a plurality of diamond particles having a particle size from about 0.1 micron to about 40 micron, more preferably from about 0.1 to about 15 micron and most preferably about 10 micron. Other suitable hard particle materials 100 include but are not limited to boron compounds; alumina compounds; partially stabilized zirconia; carbides, including tungsten carbide, chrome carbide, vanadium carbide, boron carbide, complex carbides, silicon carbide, ceramics, beryllium compounds, and other naturally occurring minerals. An exemplary process for coating the preferably titanium golf club head 10 with diamond particles 100 is disclosed in commonly owned U. S. Patent Application No. 09/288,443 filed on April 8,1999, which is hereby incorporated by reference in its entirety. By disposing a hard material, such as diamond particles 100, on ball striking face surface 22, a hard driving surface is created which results in greater energy transfer at impact between the golf ball and ball striking face surface 22. Consequently, greater distance can be realized by disposing diamond particles 100 on ball striking face surface 22 due to creating more power by greater energy transfer. In addition, because of the hardness of diamond particles 100, a durable ball striking face surface 22 is also created and the life of ball striking face surface 22 consequently is lengthened.

In yet another aspect of the present invention and as shown in FIGURE 8, golf club head 10 includes a polymeric insert 110 formed in ball striking face surface 22. Formed in ball striking face surface 22 is an insert receiving recess 120 formed rearwardly into golf putter head 10 from face surface 22. It is within the scope of the present invention that insert receiving recess 120 may take a variety of sizes and shapes and the generally rectangular insert receiving recess 120 shown in FIGURE 8 is merely exemplary in nature and not limiting. Insert receiving recess 120 receives polymeric insert 110 which is similarly shaped as insert receiving recess 120.

Polymeric insert 110 is formed of a suitable thermoplastic material or a thermosetting material and preferably comprises polyurethane, nylon, and more preferably comprises a phenolic material. Polymeric insert 110 has a width, W,

(FIGURE 8) preferably between about 1/2 the width of face surface 22 to the about the full width of face surface 22. Polymeric insert 110 has a height, H, (FIGURE 8) between about 1/2 the width of face surface 22 to the about the full width of face surface 22, and preferably the height, H, is between about 60 % to about 90% of the height of face surface 22. Preferably, the width, W, and height, H, of polymeric insert 110 is such that polymeric insert 110 covers between about 30% to about 100% of the surface area of face surface 22 of golf putter head 10. Polymeric insert 110 has a forward surface 112 which comprises the striking surface which impacts the golf ball during a swinging motion by the golfer. Polymeric insert 110 also includes a thickness, T, which is about. 01 inches to about. 33 inches and preferably between about. 06 inches and about. 125 inches. The above-mentioned dimensions are recited for purpose of illustration of one preferred embodiment of the present invention and are not to be interpreted as being limiting of the scope of the present invention. In accordance with the present invention, polymeric insert 110 includes the plurality of hard particles 100 disposed and encaptured within polymeric insert 110 so that at least a portion of the plurality of hard particles 100 protrudes from forward surface 112 to form a hard, durable striking surface. Preferably, the plurality of hard particles 100 comprises a plurality of diamond particles having a particle size between about 0.1 micron and about 40 micron, more preferably about 0.1 micron to about 15 micron and most preferably about 10 micron.

Any suitable method of manufacturing golf club head 10 including polymeric insert 110 may be used in accordance with the present invention. For example, one exemplary method is a compound press process. When this process is used, golf club head 10 is manufactured by providing a conventional golf putter head having insert receiving recess 120 already formed in forward surface 112 thereof by using an appropriate die cast during a molding process. Alternatively, insert receiving recess 120 may be formed in golf club head 10 by a machining process, as is known in the art. It is also within the scope of the present invention that insert receiving recess 120 may be formed by other known processes.

After insert receiving recess 120 is formed, polymeric insert 110 is formed and is disposed securely within insert receiving recess 120. Polymeric insert 110 may be formed and disposed within insert receiving recess 120 by a compound press process in which either the thermoplastic or thermosetting material along with the plurality of hard particles 100 are pressed into insert receiving recess 120 under heat and pressure. When a compound press process is used, either the thermoplastic or thermosetting material is preferably provided in powder form and is mixed with a predetermined amount of hard particles 100. Preferably, polymeric insert 110 comprises between about 20% to about 45% by volume of hard particles 100 and more preferably comprises about 25% by volume of hard particles 33. Once the thermoplastic or thermosetting powder is mixed with the plurality of hard particles 100, both are disposed within insert receiving recess 120 and subjected to what is known in the art as a"hot press compression", whereby the thermoplastic or thermosetting powder and the plurality of hard particles 100 are compounded into insert receiving recess 120 so that polymeric insert 110 is formed and secured within insert receiving recess 120. The compounding or pressing process which forms polymeric insert 110 comprises compounding either the thermoplastic or thermosetting powder and the plurality of hard particles 100 under a predetermined heat and pressure to form a hardened, plasticized polymeric insert 120, wherein at least a portion of the plurality of hard particles 100 protrudes from forward surface 112 thereof after the compounding process is completed. The compounding process is preferably done under pressures between about 2000 lbs/sq. inch to about 5000 lbs/sq. inch and temperatures between about 250° F to about 350° F. It being understood that these values are given for example only and do not limit the scope of the present invention. When polymeric insert 110 is formed using the above-recited compounding process, one preferred thermoplastic material for use in powder form comprises a phenolic material. A preferred phenolic material is commercially available from Borden under the trade name Barchum 1984.

Alternatively, polymeric insert 110 is formed by an injection molding process. As is known in the art, injection molding is a processing technique for converting thermoplastic and thermosetting materials into final products, such as polymeric insert 110 for use in golf club head 10. Most conventional injection molding processes comprise either a reciprocating-screw system or a two-stage screw system. Both systems involve the plasticization of the thermoplastic or thermosetting material, wherein the hot, plasticized material is injected into a mold where it is maintained under pressure. When the plastic material has sufficiently solidified, the mold opens and the plastic piece (s) is ejected. and then may be disposed in insert receiving recess 120 by known methods.

Turning now to FIGURE 9 in which a third embodiment of the present invention is provided. In this embodiment, first central surface 54 is substantially replaced with a sole weight 150. This embodiment is particularly preferred when golf club head 10 is used on a 3 or 5 wood-type golf club. Sole weight 150 comprises known golf weighting material and preferably comprises a heavy metal and more preferably is formed of tungsten or bronze. In one exemplary embodiment, sole weight 150 has a complementary shape as first central surface 54 and covers approximately about 80% of first central surface 54. In an exemplary embodiment, an approximate 1/8 inch border is provided between peripheral edges of sole weight 150 and peripheral edges of first central surface 54.

Sole weight 150 may be disposed within first central surface 54 by known methods including forming a recess 160 in first central surface 54 and subsequently disposing sole weight 150 therein by known methods. It being understood that the top surface of sole weight 150 is planar with the surrounding portions of first central surface 54. By disposing sole weight 150 in sole 14, the center of gravity of golf club head 10 is lowered in the head. This results in a golf ball being driven upwardly in the air more rapidly upon impact with golf club head 10 than would be the case in a golf club head having a higher center of gravity. Because first central surface 54 is centrally located in the raised portion of sole 14, the lowered center of

gravity is also conveniently centered in sole 14 resulting in this increased performance.

The most arresting facts about the game of golf is that everything which happens to an ensuing shot is decided in a very short space of time. For almost all golf shots, the time between a point on the clubface first striking against the golf ball and the time when the golf ball springs completely clear of the clubface and away into flight is about half a millisecond (. 0005 second). The golf stroke is a collision between the clubface and the golf ball. How fast the clubhead and golf ball move depends upon the relative weights of each and speeds prior to impact. Assume that the golf ball is a constant and the clubhead is traveling at 100 miles per hour. In this example, at the moment of impact, the golf ball moves at about 80 mph, while the clubhead slows to 80 mph. Since, the golf ball is elastic it springs forward increasing its speed to 135 mph and slows the clubhead even further to about 70 mph. Creating a theoretical mathematical model of the collision should produce a ball speed of 165 mph. The difference of speed between 165 mph and the observed speed of 135 mph is due to a combination of factors including (1) the elasticity of the golf ball, (2) the compression of the club face, and (3) the flex of the shaft.

Since the golf ball is a constant due to the rules of the United States Golf Association (USGA), the hardness of the clubface and the rigidity of the shaft can be improved to minimize energy loss. From a practical sense, the shaft must have flexibility to allow the player to store sufficient energy in the shaft to achieve clubhead speeds of about 100 mph or greater. But scrutiny of the shockwave created at impact lasting l/2 a millisecond traveling at the speed of starting at the point of impact moving through the clubface and up the shaft will have reached 6-11 inches up the shaft by the time the golf ball has left the clubface.

One can conclude that in order to minimize energy lost, a design of a hard clubface and a very rigid shaft tip are preferred while allowing the body of the shaft to be as flexible as practical. In terms of the present invention, golf club head 10 provides such a design because of the hard clubface and the preferred composite

shaft formed of kevlar and graphite fibers commercially available from the assignee under the trade name XXL shaft and subject of the U. S. Patent Application mentioned hereinbefore. Golf club head 10 of the present invention minimizes the energy lost during the collision event with the golf ball by providing a hard ball striking face surface 22, by providing crown rigidy due to the thickness of top surface 12, and by providing a wide body hosel 16. All of these attributes of golf club head 10 serve to reduce the energy loss of the golf ball during the point of contact between the golf ball and the ball striking face surface 22 and the ensuing elastic action and flight of the golf ball.

While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is understood that the present invention has been described by way of illustrations and not limitation.

What is claimed is: