Golf Club Head With Complex Curvature For The Sole And/or The Striking Face

Abstract

A golf club is provided with a uniquely curved sole for assisting the golfer in keeping the face of the club pointed in a line to the target when, as the ball is addressed, the lie of the club differs from the normal lie. The sole is curved upwardly from the central portion to the heel portion and further curved upwardly and away, at progressively greater rates, from the front face to the rear face. The sole may also be curved from the central portion to the toe portion and further curved downwardly and away at progressively greater rates, from the front face to the rear face. The face of a wood golf club is also provided with a bulge or convex curvature about an axis in a first plane parallel to a plane tangent to the center of the club face and lying in a second plane parallel to the club shaft and passing through a line between the center of the club face and the target at the time of addressing the ball, and a roll or convex curvature about an axis perpendicular to the bulge axis curvature. The radius of curvature for roll is less than for bulge. The rear of the wooden head is extended and tapered, and concentrated weights are placed as much in the toe and the extended rear portion of head as possible.

Description

BACKGROUND OF THE INVENTION

This invention relates to golf clubs, and more particularly to novel and improved head configurations.

It has become standard practice to design golf clubs with features intended to compensate for a tendency to hook or slice the ball due to an improper swing. This is particularly true of the longer clubs, commonly referred to as woods, such as a driver, because they produce more pronounced effects when the ball is hit off center (i.e., when the ball is hit at a point displaced from the "center" or "sweet spot" of the club face or off line (i.e., when the ball is hit with the club face not square with its initial intended line of travel).

An offcenter impact produces a hook or a slice because the impact is either on the toe side or heel side of the center of gravity of the club head, causing the face to open or close, Upon opening, there is a tendency for both slicing and hooking spin to be imparted to the ball, but the hooking spin predominates due to the club head rotating about its "vertical" axis in one or the other direction to cause the ball to spin about a parallel axis in the opposite direction. For example, even though an open face will initially change the direction of the ball toward the toe, the hooking spin will bring the ball around violently across the intended line of flight. Impact on the heel side of the club face produces just the reverse result.

To compensate for the hooking and slicing effects of offcenter impact with woods, manufacturers provide a bulge (a convex curve on the face of the club about an axis in a plane passing through a line to the target from the center of the club face and perpendicular to the sole plate). The result is to produce a spin on the ball due to the club face being effectively opened or closed by the bulge enough to compensate for an opposite spin imparted to the ball due to rotation of the club head when impact with the ball is off center. Thus a convex bulge produces compensating forces on the ball in flight to bring it back to within at least 10 to 20 yards of the intended line to the target, but not without some loss in distance due to drag resulting from the spin imparted to the ball.

The bulge also results in deeper penetration of the golf club head into the center of the golf ball during impact. The result is that the ball will leave the club head with greater velocity due to reaction as the ball resumes its original shape. That is so because golf balls are designed to have resilience, i.e., to have the ability to deform against the club face upon impact and to spring forcefully back into shape. This action and reaction is usually further enhanced by providing a roll on the face of the club in the form of a convex curve on the face of the club about an axis parallel to the sole of the club. Since the axes of the two convex curvatures (bulge and roll) are orthogonal, the roll has little effect on the compensation introduced by the bulge in the form of side spin. Roll will, however, tend to decrease spin of the ball around a horizontal axis (back and top spin), and therefore increase the distance the ball will carry in flight.

It has been discovered that the prior art bulge and roll on a club face will not produce the exact desired results because they are oriented about vertical and horizontal axes, respectively, which presumes the ball is being struck with the club head oriented to the normal lie with the sole of the club parallel to a horizontal plane passing through the center of the ball. It also presumes that the club head will rotate about an axis vertical to the sole plate when offcenter impact with the ball is on the toe or heel. However, in actuality the swing of the golf club at the moment of impact is in a plane passing through a line to the target and substantially parallel to the club shaft.

It sometimes happens that a golfer will consciously, or subconsciously address the ball with a lie that is greater, or smaller, than a normal lie. The lie of a club is the angle which the shaft makes with a horizontal line tangent to the sole, and a "normal" lie is that angle with the sole of the club also horizontal. For a golfer to swing consistently with the normal lie designed into the club by the manufacturer requires not only that the length of the shaft be matched to the physical dimensions of the golfer, but also that the golfer address the ball with the proper stance (distance of his feet from the ball). A closer stance will result in an increased lie and a further stance in a decreased lie, where lie is the angle between the axis of the club shaft and a horizontal line.

Variation in stance will require some changes in the mechanics of the swing required to meet the ball squarely, and a golfer quickly adjusts to that. However, a golfer may not realize that a variation in stance (lie) will result in a decrease in loft and, what may be more important, a more open face for a smaller lie further stance and a more closed face for a greater lie closer stance. If the golfer does realize this, he can compensate for it by rotating the club slightly in his hands upon addressing the ball, but except for extreme cases, such as for an uphill lie, the average golfer will not think about it. It would be desirable to provide a golf club which will effectively provide a "normal" lie for all stances (within a reasonable range) by allowing the club face to be square with the direction to the target as the golfer rests the club on the ground just behind the ball in the usual manner of addressing the ball, which is while adjusting his grip. The face may then be deliberately opened or closed if such is desired.

SUMMARY OF THE INVENTION

In accordance with the present invention, wood or iron clubs are provided with heads having a central portion tangent to a horizontal sole or ground plane from below a point at the approximate center of the striking face of the club to a rear edge of the club head remote from the striking face. That part of the sole between the central portion and the shaft, which is connected to the head at the heel, i.e., off one end of the striking face, is curved upwardly and away from the sole or ground plane with a rate of curvature progressively greater in successive planes parallel to the striking face, or a plane tangent to the striking face at the point approximately at the center of the striking face, the successive planes being taken in sequence from the striking face to the rear of the club head. The successive planes are infinite in number to provide a smoothly curved sole with the curvature more pronounced toward the rear of the club head than at the striking face. That part of the sole between the central portion and the toe, i.e. the end of the club head remote from the shaft, can also be curved upwardly to advantage, particularly in wood-type golf clubs, but with the rate of curvature progressively greater in successive planes parallel to the face, or a plane tangent to the striking face at the point approximately at the center of the striking face, taken in sequence from the rear to the striking face, with the number of successive planes again being infinite to provide a smoothly curved sole with the curvature more pronounced toward the striking face than toward the rear of the club head.

As another feature for wood-type golf clubs, the striking face is provided with a complex curvature so oriented that a face plane tangent to the approximate center of the striking face is at an obtuse angle relative to a horizontal sole or ground plane tangent to the sole measured in front of the striking face to provide the golf club with loft. The complex curvature is comprised of a first curvature of a predetermined constant radius about a first axis. That first axis is formed by the intersection of two planes; one of the two planes being parallel to the face plane and the other plane being perpendicular to the face plane and parallel to the shaft axis. The complex curvature is further comprised of a second curvature across the striking face and of a predetermined radius significantly less than the radius of the first curvature. The second curvature is formed about a second axis lying in a plane perpendicular to the face plane and perpendicular to the shaft axis. The second curvature is oriented in every segment of the striking face with its axis of curvature normal to the first axis.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention will best be understood from the following description when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear view of an iron golf club (with the shaft broken away) illustrating one feature of the present invention.

FIG. 2 is a heel view of a wood golf club illustrating various features of the invention.

FIG. 3 is a toe view of the club of FIG. 2.

FIG. 4 is a rear view of the club of FIG. 2.

FIG. 5 is a bottom (sole) view of the club of FIG. 2.

FIG. 6 is a front face view of the club of FIG. 2.

FIGS. 7 and 8 are sectional views of part of the club of FIG. 6 taken on the respective lines 7--7 and 8--8 to illustrate the bulge and roll contours thereof, respectively.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, a rear view of an iron club head 10 is shown with the hosel 11 (to which the shaft not shown is attached) cut away. The center, or "sweet spot," of the club face is on the other side directly above a central portion 12 of the sole tangent to the ground represented by a horizontal line 13. When held in that position to address a ball, the lie (defined by the angle .alpha. between the axis of the hosel and the horizontal line 13) is normal and a line perpendicular to the center of the club face lies in a plane passing through a line in the direction of the target.

If the lie .alpha. is decreased, the line perpendicular to the face of the club would point in a direction to the left of the target if the heel portion 14 were not curved up progressively more in longitudinal sections parallel to the club face taken successively from the face to the rear to allow the club head to seemingly open. Thus, as the club head is rocked back on its heel to decrease the lie .alpha., the upper edge of the club head 10 is permitted to swing back away from the ball, thereby seemingly opening the face. The actual opening of the club face is only with reference to the upper edge of the club head 10, and not with reference to the club face which, in accordance with this feature of the invention, remains in substantially the same plane, thereby maintaining a line normal thereto pointing in the same direction instead of to the left. Similarly, if the lie .alpha. is increased, the line normal to the face of the club would point to the right were it not for a toe portion 15 being curved up progressively more in longitudinal sections parallel to the club face taken successively from the rear to the face, as indicated by the dotted line which represents the leading edge of the club face from the central portion 12 out to the toe of the club head 10.

This feature of maintaining the face of the club pointing in substantially the same direction as the lie is increased or decreased from normal may be better understood from a description of the same feature for a wood club 16 in FIGS. 2 through 4 where the curved portions of the sole may be more easily illustrated. A horizontal line 17 on the sole of the club head corresponds to the central portion 12 of the iron club illustrated in FIG. 1. It is essentially a line comprising all points of the club sole tangent to the ground for a normal lie .beta. shown in FIG. 4.

The heel portion 18 of the sole is curved upwardly progressively more toward the rear 19 of the club 16 in such a manner as to bring successive parallel lines (shown in perspective for purposes of explanation only) in contact with the ground, thereby seemingly opening the face 20 of the wood club 16 to maintain a line perpendicular thereto at a point of tangency with a ball 21 (shown in dotted line) pointing in substantially the same direction.

The rate at which the upper edge of the face 20 moves away from the ball as the lie .beta. is decreased is less for a driver than, for example, a No. 5 iron since the loft of a driver is about 10.degree. while for a No. 5 iron the loft is about 30.degree., and the greater the loft of the club, the greater the face must be seemingly opened. Although a mathematical relationship could be developed for all clubs, none has been since it is sufficient to design patterns for all clubs to maintain the direction in which they point constant for a reasonable range of lies by simply shaping the heel portion 17 to accomplish that for various degrees of lie and then smoothing out the curvature, thereby interpolating for intermediate lies.

A toe portion 22 shown in FIG. 3 is similarly provided but oppositely curved as shown in FIG. 3 to achieve the same objective described for the toe portion 15 of the iron club illustrated in FIG. 1, as may be readily appreciated by comparing FIG. 1 and 4. However, although this feature is illustrated for the toe as well as the heel for both wood and iron clubs, it should be appreciated that it may be omitted in the toe of irons or woods. In that case, the direction in which a line perpendicular to the club face points is maintained constant for only lies less than normal, and not for lies greater than normal.

Another feature illustrated in FIGS. 2 and 3 is an extension and taper of the rear portion 19 of the club head. In the past, wood club heads have been provided with a greater bulge on the top and a blunt rear portion, i.e., a trailing portion which terminates about at a distance of less than three times the distance between a leading edge 26 and the center of a hosel 29, or more precisely about three times the distance between parallel planes tangent to the leading edge and a plane passing through the center line 30 of the hosel 29. This extended and tapered rear portion 19 extends a minimum of three times that distance to provide a better aerodynamic configuration, i.e., to reduce the wake of the head if the wood club 16 which reaches velocities in the vicinity of 130 miles per hour during the swing. A further advantage of such an extension is that it provides space more to the rear to place a weight 25 at a significantly greater distance from the leading edge 26 of the face 20 as shown in FIGS. 5 and 6 than would be possible in prior art clubs. The weight 25 is placed in line with (behind) a sweet spot illustrated as a small dotted circle 27 in FIG. 6.

A second weight 28 is placed near the face 20 of the club 16 and as far out on the toe as possible, as may be more clearly seen in FIG. 6. The two weights 28 and 25, and the weight already concentrated in the heel due to the mass of the hosel 29 and shaft 31, cooperate to increase the moment of inertia for any offcenter impact with the ball. The result is less of a tendency for the club head to rotate about an axis parallel to the axis 30 passing through the hosel 29 due to an offcenter stroke, and of course few strokes are made at the center (on the sweet spot 27). In other words, in this unique distribution, weights 25 and 28 are dynamically balanced by the hosel 29 and shaft 31 connected thereto to increase the resistance of the club 16 to torsion when the ball is hit offcenter.

It has been discovered that the vast majority of strokes are made with impact on a larger area of the face 20 than the sweet spot 27. That larger area is indicated generally by dotted ellipse 32 having its minor axis substantially parallel to the shaft axis 30. Accordingly, to provide improved compensation for offcenter impact, every segment of the face 20 is bulged (convexly curved) with a first radius of approximately 10 inches, for example, about an axis parallel to that minor axis, and rolled (convexly curved) with a second radius of approximately 8 inches, for example, about an axis parallel to the major axis of the ellipse 32, but always with a greater radius of curvature for the bulge. In other words every segment of the face is convexly curved with a constant radius about an axis in a first plane parallel to a plane tangent to the center 27 of the club face. That axis lies in a second plane parallel to the axis 30 of the club shaft. Every segment is also convexly curved with a constant, and smaller radius about an axis perpendicular to the axis of the bulge curvature. FIGS. 7 and 8 are sectional views taken on the lines 7--7 and 8--8 of FIG. 6 to show the bulge and roll contours (the curvatures about axes parallel to the minor and major axes of the ellipse 32). In that manner, hook and slice compensation is provided for lateral deviation of the impact from the sweet spot along a line (major axis of the ellipse 32) perpendicular to the shaft axis 30 rather than parallel to a tangent 33 to the sole of the club head 16. This is because any tendency to swing out is accompanied by a tendency to raise the club, and vice versa, as though the upwardly extended axis of the club were fixed on a point, for that is what a golfer seeks to achieve, namely a swing about a fixed point between his shoulders.

Although reference has been made throughout to iron and wood clubs, it should be understood that the reference is to types of clubs as they are commonly called, and not to the type of material from which the club heads are made. Accordingly, it is not intended that the scope of the invention be determined by the disclosed exemplary embodiments, but rather should be determined by the breadth of the appended claims.

Claims

What is claimed is:

1. In a wood-type golf club, a shaft having a longitudinal axis and a head having a sole extending laterally from one end of said shaft at an acute angle measured in a vertical plane between said axis and a horizontal sole plane tangent to said sole, said head having a striking face with a complex convex curvature so oriented that a face plane tangent to a point at the approximate center thereof is at a desired obtuse angle relative to said horizontal sole plane measured in front of said face, said complex curvature consisting of: a bulge formed as a first curvature of a predetermined constant radius about a first axis defined by the intersection of two planes, one of said two planes being parallel to said face plane and the other of said two planes being both perpendicular to said face plane and parallel to said shaft axis; and a roll formed as a second curvature across said face and of a predetermined radius significantly less than the radius of said first curvature, said second curvature being formed about a second axis, said second axis lying in a plane perpendicular to said face plane and perpendicular to said shaft axis, said second curvature being oriented in every segment of said face with its axis of curvature normal to said first axis.

2. In a wood-type golf club as defined in claim 1 the further improvement comprising said sole having a central portion tangent to said sole plane along a central portion passing from directly below said point to a rear edge of said head remote from said face, said sole being curved upwardly and away from said sole plane between said central portion and said shaft with a rate of curvature progressively greater in successive planes parallel to said face plane taken in sequence from said face plane to said rear edge, where said successive planes are infinite in number to provide a smoothly curved sole with the curvature more pronounced toward said rear edge than toward said face plane.

3. In a wood-type golf club as defined in claim 1 wherein said sole is curved upwardly between said central portion and an end of said head remote from said shaft with a rate of curvature progressively greater in successive planes parallel to said face plane taken in sequence from said rear edge to said face plane, where said successive planes are infinite in number to provide a smoothly curved sole with the curvature more pronounced toward said face plane than said rear edge.

4. In a golf club, a shaft having a longitudinal axis and an elongated head extending laterally from one end of said shaft at an acute angle measured in a vertical plane between said axis and a horizontal sole plane tangent to the sole of said head, said head having a striking face terminating in a front leading edge, a rear face terminating in a rear edge remote from said front edge, toe and heel portions, said sole having a complex curvature comprising, a central portion tangent to said sole plane, said heel portion being curved upwardly from said central portion towards the end of the heel portion of the club head, said heel portion of the sole being further curved upwardly and away from said front edge with a rate of curvature progressively greater in successive planes parallel to a striking face plane taken in sequence from said plane of said striking face to said rear face wherein successive planes are infinite in number to provide a smoothly curved sole with the curvature more pronounced toward said rear edge than said front edge, such complex curvature of the sole resulting in the upper edge of the striking face of the club head opening up in a rotating clockwise direction away from said vertical plane while maintaining a line normal to said striking face in substantially the same direction instead of to the left of the intended target when said club is rocked backwards on said heel to decrease said acute angle.

5. In a golf club, the combination as defined in claim 4 wherein said toe portion also being curved upwardly from said central portion towards the end of the toe portion of the club head, said toe portion of said sole being further curved downwardly and away from said front edge with a rate of curvature progressively greater in successive planes parallel to said plane of said striking face taken in sequence from the plane of said striking face to said rear face wherein said successive planes are infinite in number to provide a smoothly curved sole with the curvature more pronounced toward said front edge than said rear edge, such complex curvature of the sole resulting in the upper edge of the striking face of the club head closing in a rotating counterclockwise direction toward said vertical plane while maintaining a line normal to said striking face in substantially the same direction instead of to the right of the intended target when said club is rocked forwards on said toe to increase said acute angle.

6. In a golf club, the combination as defined in claim 5 wherein said head is for an iron-type club and is made of metal.

7. In a golf club, the combination as defined in claim 5 wherein said head is for a wood-type club.