METAL WOOD GOLF CLUBHEAD

Abstract: A metal wood golf clubhead has a length "L" representing the distance, measured perpendicular to the centerline, between the heel and toe; a rearmost point that lies at a distance "A", measured perpendicular to said centerline, from the heel; and a rear edge having a radius of curvature R2, in the region of the rearmost point. In accordance with one aspect of the invention, the distance "A" from the heel to the rearmost point on the clubhead rear edge is at least 60 mm and/or at least 56 % of the overall clubhead length "L". In accordance with another aspect of the invention, the clubhead has a volume of at least 180 cm<3>, the center of curvature of the rear edge, in the region of the rearmost point, is offset from the club's centerline CL toward the toe, and the radius of curvature R2 in the region of the rearmost point is less than 41 mm.

Description: METAL WOOD GOLF CLUBHEAD BACKGROUND OF THE INVENTION The present invention relates to metal wood golf clubs, and particularly to drivers, 3 woods, and 4 woods. In the game of golf, the driver produces the greatest distance of ball travel, and therefore is normally the club of choice when teeing off on par 4 and par 5 holes. It is usually difficult to hit the ball with a driver off the fairway or rough, and for those situations the greatest distance, when conditions allow, can be attained by hitting a 3 wood or 4 wood (herein referred to as "fairway woods") . In recent years, the traditional wooden heads of the driver and fairway woods have been replaced by heads having a shell made of metal, such clubs being referred to as "metal woods" . The use of metal in place of a solid wood head allows greater variability in the design of clubhead' s shape, weight, and balance . While drivers and fairway woods have the potential to hit the ball farther, the longer shaft of the driver makes it the most difficult golf club for most players to control, resulting in frequent hooks, slices, and other misdirected hits. Similarly, due to their longer shafts, fairway woods tend to be more difficult to control than irons . It would therefore be desirable to provide a metal wood driver and fairway woods that are more stable and easier to swing. SUMMARY OF THE INVENTION Studies have shown that a typical golfer tends to strike the ball not in the geometric center of the club face, but rather, towards the toe. The present invention relocates the center of gravity to a position approximating the average location of ball impact. The present invention also provides a clubface in which the vertical apex is offset towards the toe, also lying closer to the location of average ball impact, thereby providing a bigger target to hit the ball . The present invention thereby makes it easier for the average golfer to hit a good shot . A metal wood golf clubhead has a length "L" representing the distance, measured perpendicular to the centerline of the face projected perpendicularly rearward, between the heel and toe; a rearmost point that lies at a distance "A", measured perpendicular to the centerline, from the heel; and a rear edge having a radius of curvature R2 in the region of the rearmost point . In accordance with one aspect of the invention, the distance "A" from the heel to the rearmost point on the clubhead rear edge is at least 60 mm and/or at least 56% of the overall clubhead length "L" . In accordance with another aspect of the invention, the clubhead has a volume of at least 180 cm 3 , the rear edge center of curvature, in the region of the rearmost point, is offset from the club's centerline CL toward the toe, and the radius of curvature R2 in the region of the rearmost point is less than 40.0 mm. The foregoing geometry has the effect of locating more mass near the toe of the club, advancing the center of gravity. Thus, for the average player, the center of gravity is closer to the actual point of ball impact. Preferably, the clubhead has an inset hosel, and is utilized with a lightweight shaft. For a better understanding of the invention, reference is made to the following detailed description of a preferred embodiment, taken in conjunction with the drawings accompanying the application. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view of a driver clubhead according to the invention; Fig. 2 is front view of the clubhead; Fig. 3 is a rear view of the clubhead; Fig. 4 is a cross-sectional view of the clubhead, taken through lines 4-4 of Fig. 1; Fig. 5 is side view of the clubhead looking in a direction toward the toe; Fig. 6 is a bottom view of the clubhead; and Fig. 7 is a plan view of the clubhead, without the hosel, showing the outline of the head shape projected onto a plane. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Figs. 1-7 show an example of a driver clubhead having a metal shell 10 defining a top surface 12, a heel 14, a toe 16, a front face 18, and an inset hosel 20 extending from the top surface 12. The shell 10 defines a hollow interior, but which may include reinforcement members in a known manner. In the exemplary embodiment, the front face 18 has a loft angle α (see Fig. 5) of 10 degrees, and a height "H" (see Fig. 5) of 45.45 mm. Drivers, however, can vary in loft angles, and other conventional loft angles can be employed. The example clubhead has A plurality of grooves 19 are formed in the front face so as to be parallel to the ground when the club is resting on its touchpoint in its normal address position (shown in Fig. 2) . As shown, the upper edge of the front face is curved, and has a vertical apex 21 (the highest vertical point) which is offset from the touchpoint in the direction of the toe. As shown in Figs. 4 and 6, a sole plate 22 is affixed to the main shell 10, for example by welding in a known manner. A plurality of support tabs 23, extending from the bottom portion of the shell 10, may be used to position the sole plate 22 prior to welding. The sole plate 22 can have any desirable shape, for example be provided with a sole keel 25 (see Figs. 4 and 5) or cutouts. Referring to Fig. 7, the clubhead, when projected onto a plane, is shaped so as to have a continuous curvature of varying radii. The front face 18 is a region of constant, relatively large radius of curvature RI (known as "bulge"), about a center of curvature 24, that extends between points "A" and "B" . The rear edge 30 of the clubhead, in the region to either side of the rearmost point 26, has a smaller radius of curvature R2. The edges of the intermediate portions 32, 34 of the clubhead, connecting rear edge 30 with the heel 14 and toe 16, respectively, have a substantially larger radius of curvature than the rear edge 30. The centerline "CL" of the club extends perpendicular to the club face 18, at its forward-most point 19 when the club is at the normal address position, so as to intersect the center of rotation 24. In the exemplary embodiment, the centerline CL is disposed approximately midway between "A" and "B" . The clubhead has a length "L", which is the distance, measured perpendicular to the centerline CL, between the heel 14 and toe 16. The width "W" of the clubhead is the distance, measured parallel to the centerline, between the front face 18 and the rearmost point 26 on the rear edge 30. Finally, the rearmost point 26 lies at a distance "A", measured perpendicular to the centerline CL, from the heel 14. The rearmost point 26, and the center of curvature 28 of R2 , are offset from the clubhead centerline CL toward the toe by a distance "0" . In the exemplary embodiment, the clubhead has a length "L" of 109.3 mm, a width "W" of 88.0 mm, a club face radius of curvature RI of 278.3 mm, a club face length (distance between "A" and "B") of approximately 90 mm, and a radius of curvature R2, in the region of the rearmost point 26, of 40.3 mm. The rearmost point 26 lies at a distance "A" of 64.3 mm from the heel 14, and the rearmost point 26 and center of curvature 28 of R2 are offset from the clubhead centerline CL by a distance "0" of 9.9 mm. The clubhead, viewed in plan view, covers an area of 7126 mm 2 , and the clubhead occupies a total volume of 240 cm 3 . In accordance with one aspect of the invention, the distance "A" from the heel to the rearmost point 26 on the rear surface 30 is at least 60 mm and/or at least 56% of the overall clubhead length "L" . In accordance with another aspect of the invention, the clubhead has a volume of at least 180 cm 3 , the center of curvature 28 of the rear edge, in the region of the rearmost point 26, is offset from the club's centerline CL toward the toe, and the radius of curvature R2 in the region of the rearmost point 26 is less than 41 mm. And, in accordance with another aspect of the invention, the vertical apex 21 of the front face is offset toward the toe of the club, preferably by a distance of approximately 14 mm. As can be seen from Fig. 1, the geometry of the present clubhead has tendency to locate more mass towards the toe 16 due to the shape of the head, and therefore move the center of gravity toward the toe. This produces a more solid impact for balls hit near the toe. In addition, the vertical apex 21 of the clubface is offset towards the toe, also approximately in the location where the ball tends most to be hit, to provide a bigger target to hit the ball. At the same time, despite the higher center of gravity, the clubhead is easier to square during the forward swing, due to the inset location of the hosel. The clubhead is preferably utilized with a lightweight shaft, which combination of features make the club easier to swing. The head shape of the present invention was compared with other woods on the market, with the differences represented in the table below. Table 1 σ> The foregoing represents preferred embodiments of the invention. Variations and modifications will be apparent to persons skilled in the art, without departing from the inventive concepts disclosed herein. All such modifications and variations are intended to be within the skill of the art, as defined in the following claims.

Claims: CLAIMS We claim: 1. A metal wood golf clubhead having a front face with a forward-most point and a centerline extending perpendicular thereto, a heel, a toe, and a rear edge having a rearmost point; wherein said clubhead has a length "L" representing the distance, measured perpendicular to said centerline, between said heel and toe, and wherein said rearmost point lies at a distance "A", measured perpendicular to said centerline, from said heel; and wherein said distance "A" is greater than 60 mm. 2. A metal wood golf clubhead according to claim 1, wherein said distance "A" is approximately 64 mm. 3. A metal wood golf clubhead according to claim 2, wherein said length "L" is greater than 100 mm. 4. A metal wood golf clubhead according to claim 3, wherein said length "L" is approximately 109 mm. 5. A metal wood golf clubhead according to claim 1, wherein said length "L" is greater than 100 mm. 6. A metal wood golf clubhead according to claim 5, wherein said length "L" is approximately 109 mm. 7. A metal wood golf clubhead according to claim 1, wherein the ratio of said distance "A" to said length "L" is at least 0.56. 8. A metal wood golf clubhead according to claim 7, wherein the ratio of said distance "A" to said length "L" is approximately 0.6. 9. A metal wood golf clubhead according to claim 7, wherein the length "L" is at least 100 mm. 10. A metal wood golf clubhead according to claim 9, wherein the length "L" is approximately 109 mm. 11. A metal wood golf clubhead according to claim 1, wherein said rear edge, in the region of said rearmost point, has a radius of curvature R2 having a center of rotation offset from said centerline in the direction of said toe, wherein said clubhead occupies an overall volume of at least 180 cubic centimeters, and wherein said radius of curvature R2 is less than 41 mm. 12. A metal wood golf clubhead according to claim 11, wherein said radius of curvature R2 is approximately 40 mm. 13. A metal wood golf clubhead according to claim 11, wherein said length "L" is greater than 100 mm. 14. A metal wood golf clubhead according to claim 14, wherein the ratio of said distance "A" to said length "L" is at least 0.56. 15. A metal wood golf clubhead according to claim 11, wherein said radius of curvature R2 is approximately 40 mm, wherein said length "L" is approximately 109 mm, and wherein the ratio of said distance "A" to said length "L" is approximately 0.6. 16. A metal wood golf clubhead having a front face with a forward-most point and a centerline extending perpendicular thereto, a heel, a toe, and a rear edge having a rearmost point; wherein said clubhead has a length "L" representing the distance, measured perpendicular to said centerline, between said heel and toe, and wherein said rearmost point lies at a distance "A" , measured perpendicular to said centerline, from said heel; and wherein the ratio of said distance "A" to said length "L" is at least 0.56. 17. A metal wood golf clubhead according to claim 16, wherein the ratio of said distance "A" to said length "L" is approximately 0.6. 18. A metal wood golf clubhead having a front face with a forward-most point and a centerline extending perpendicular thereto, a heel, a toe, and a rear edge having a rearmost point; wherein said rear edge, in the region of said rearmost point, has a radius of curvature R2 having a center of rotation offset from said centerline in the direction of said toe, wherein said clubhead occupies an overall volume of at least 180 cubic centimeters, and wherein said radius of curvature R2 is less than 41 mm. 19. A metal wood golf clubhead according to claim 18, wherein said radius of curvature R2 is approximately 40 mm. 20. A metal wood golf clubhead having a touchpoint and a centerline extending vertically therethrough, and further comprising a front face having a vertical apex, a heel, and a toe, wherein said vertical apex is offset from said centerline, in a direction perpendicular to said centerline toward said toe, a distance of at least 10 mm. 21. A metal wood golf clubhead according to claim 20, wherein said vertical apex is offset by a distance of approximately 14 mm.

Inventors: DAVIS STEPHEN J, HULOCK RICHARD P, MEYER DEAN E, DAVIS, STEPHEN, J., HULOCK, RICHARD, P., MEYER, DEAN, E.
Applicants: PRINCE SPORTS GROUP INC, PRINCE SPORTS GROUP, INC.
Application year: 1997
Main classification: A63B53
IPC codes: A63B53