# Patent

## Title
Set of iron-type golf clubs having a progressive sole configuration

## Abstract

The present invention is directed to a set of iron-type golf clubs having a progressive sole configuration through the set. In particular, the inventive golf clubs include a consistent relationship between the ground contact and center of gravity throughout the set and a progressive sole configuration that provides desired bounce for each club within the set. The progressive sole configuration includes a progressive sole camber throughout the set of iron-type golf clubs.

## Background
FIELD OF THE INVENTION
This invention generally relates to golf clubs, and more specifically to the sole configuration of iron-type golf clubs.
BACKGROUND OF THE INVENTION
Iron-type golf clubs generally include a face that includes a ball striking surface and a body that supports the face, provides desired mass properties and includes a sole that is configured to contact the ground during a swing. The face includes a ball striking surface that generally includes a plurality of score lines or grooves that are positioned to impart spin on the ball during impact. The body is generally designed to provide mass that is distributed to tailor the behavior of the club, especially during impact with the ball. The sole configuration also dictates the behavior of the club caused by its interaction with the ground during a swing.
The sole configuration of iron-type golf clubs is particularly important due to the wide variety of surfaces that it contacts and because if configured properly, the behavior it creates can protect a user from injury. The sole is usually slightly curved between a leading edge and a trailing edge so that when the club is placed on the ground the leading edge and the trailing edge are located above the ground. The angular relationship between a line extending from the leading edge to the trailing edge and the ground is traditional bounce and curvature included on the sole between the leading edge and the trailing edge affects the effective bounce of a golf club. A positive bounce corresponds to a generally forwardly inclined (i.e., the leading edge is elevated relative to the trailing edge) profile that assists in preventing the club head from digging into the ground and substantially reducing the club head speed during a swing.
Prior golf clubs have included a variety of sole configurations. For example, U.S. Pat. No. 5,549,296 to Gilbert describes a golf club that has a sole including a positive bounce surface, a trailing sole surface and a crescent surface. The crescent surface is between the positive bounce surface and the trailing sole surface and has a bounce angle that is selected so that the contact point of the golf club head at address is located in the center of a rear boundary of the crescent surface.
In another example, U.S. Pat. No. 6,471,601 to McCabe et al. describes a golf club that includes a bottom crescent surface, a positive bounce surface, a heel surface and a toe surface. The bottom crescent surface has a generally straight aft boundary that is proximate a trailing edge of the club head and a curved front boundary. The bottom crescent is also configured so that it is substantially flat with the ground at address.
There is a need for an improved golf club sole configuration for a set of iron-type golf clubs that increases balance and playability for the clubs throughout the set.
SUMMARY OF THE INVENTION
The present invention is directed to a set of iron-type golf clubs. The inventive set of iron-type golf clubs provides a sole configuration that varies through the set to provide consistent balance and playability.
In an embodiment, a set of iron-type golf clubs includes at least first, second and third golf clubs. The first golf club has a first golf club head with a first loft angle, a ground contact that is co-planar with a first center of gravity of the golf club in a vertical plane extending in a heel-toe direction, and a first sole camber with a first radius of curvature. The second golf club has a second golf club head with a second loft angle that is greater than the first loft angle, a ground contact that is co-planar with a second center of gravity of the second golf club head in a vertical plane extending in a heel-toe direction, and a second sole camber with a second radius of curvature that is greater than the first radius of curvature. The third golf club has a third golf club head with a third loft angle that is greater than the second loft angle, a ground contact that is co-planar with a third center of gravity of the third golf club head in a vertical plane extending in a heel-toe direction, and a third sole camber with a third radius of curvature that is greater than the second radius of curvature. The first golf club, the second golf club and the third golf club each have an effective bounce of 1.0°-15.0°.
In another embodiment, a set of iron-type golf clubs includes at least first, second and third golf clubs. The first golf club has a first golf club head with a first loft angle, a first ground contact, and a first sole camber with a first radius of curvature. The second golf club has a second golf club head having a second loft angle that is greater than the first loft angle, a second ground contact, and a second sole camber with a second radius of curvature that is greater than the first radius of curvature. The third golf club has a third golf club head with a third loft angle that is greater than the second loft angle, a third ground contact, and a third sole camber with a third radius of curvature that is greater than the second radius of curvature. The first golf club, the second golf club and the third golf club have constant horizontal spacing between the ground contact and the center of gravity through the set and each golf club has an effective bounce of 1.0°-15.0°.



BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:
FIG. 1 is a front perspective view of an iron-type golf club in accordance with the present invention;
FIG. 2 is a rear perspective view of the golf club of FIG. 1;
FIG. 3 is a cross-sectional view of a plurality of iron-type golf clubs included in a set in accordance with the present invention;
FIG. 4 is a cross-sectional view of a golf club of the set shown in FIG. 3;
FIG. 5 is a cross-sectional view of a golf club of the set shown in FIG. 3;
FIG. 6 is a cross-sectional view of a golf club of the set shown in FIG. 3;
FIG. 7 is a bottom view of a golf club head in accordance with the present invention;
FIG. 8 is a cross-sectional view of a portion of the golf club head of FIG. 7; and
FIG. 9 is an exploded view of a back plate of a golf club in accordance with the present invention.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is directed to iron-type golf clubs having a progressive sole configuration through a set. In particular, the inventive golf clubs generally include a consistent relationship between the ground contact and center of gravity throughout the set and a progressive sole configuration that provides desired bounce for each club within the set. The progressive sole configuration includes a progressive sole camber throughout the set of iron-type golf clubs.
Referring to FIGS. 1 and 2, an iron-type golf club head 10 generally includes a face 12 and a body 16 that supports face 12. Face 12 includes a generally planar ball striking surface 14 and a plurality of score lines 18, or grooves, that extend into face 12 from ball striking surface 14. Score lines 18 assist in imparting spin to a golf ball during impact and may have various configurations to produce desired spin characteristics.
In addition to providing support for face 12, body 16 provides the majority of the mass of club head 10. Body 16 is configured to distribute the mass so that club head has a desired behavior during impact with a golf ball and/or the ground during a swing. For example, body 16 may have a muscle-back or a cavity-back configuration. As shown, body 16 has a cavity-back configuration that provides perimeter weighting to increase the moment of inertia of club head 10 to add forgiveness during misaligned ball impacts. In particular, the mass of body 16 is concentrated in locations spaced from the geometric center of club head 10, such as in a heel portion 20 and a toe portion 22. Additionally, the mass of body 16 is concentrated below the geometric center in a sole portion 24 and above the geometric center in a top line portion 26, with a greater percentage of the mass located in sole portion 24 so that the height of the center of gravity of club head 10 is reduced. Body 16 also includes a hosel 28 for attaching a golf club shaft.
Face 12 and body 16 may be constructed from any metal or non-metal material and face 12 may be integrated with body into a single component or face 12 may be constructed separately and attached to body 16. Preferably, the material of face 12 has a density in the range of about 2 g/cm3 to about 8 g/cm3 and the material of body 16 has a density in the range of about 6 g/cm3 to about 19 g/cm3. Suitable materials for face 12 include metallic materials such as aluminum, stainless steel, carbon steel, titanium, magnesium, and alloys thereof; and non-metallic materials such as carbon fiber composites, plastics and fiber reinforced plastics. Suitable materials for body 16 include, but are not limited to, stainless steel, carbon steel, titanium, aluminum and alloys thereof and portions may be constructed from materials having greater density such as lead, tungsten, gold, or silver to provide a desired mass distribution.
A back plate 30 may also be attached to body 16. Back plate 30 may be coupled to any portion of body 16, such as within a cavity 32 defined by the perimeter weighting of body 16. Back plate 30 may be constructed to provide weight adjustment, vibration damping and/or desired aesthetics as will be described in greater detail below.
Referring to FIG. 3, the relationship between the location of the center of gravity and the ground contact is consistent throughout a set of iron-type golf clubs. The set of golf clubs is assembled with a plurality of golf clubs 40, 46, 52 that have progressively increasing loft angles (α). Because of the change in loft angle, the associated mass distribution and the location of the center of gravity (CG) are unique for each club in the set. For example, golf club 40 corresponds to a long-iron and has the lowest loft angle of the clubs in the set and, in the illustrated example, sole 42 has the smallest length from the leading edge to the trailing edge (also referred to herein as sole width). Golf club 52 corresponds to a short-iron and has the greatest loft angle in the set and, in the illustrated example, sole 54 has the greatest length. Golf club 46 corresponds to a mid-iron and has an intermediate loft angle and sole 48 has an intermediate length.
The clubs of the set shown in FIG. 3 include ground contact locations that are vertically aligned with the respective center of gravity locations. Since each of the clubs has unique dimensions and a unique mass distribution the location of the ground contact varies along the length of the sole. In particular, the ground contact A of golf club 40 is located closer to leading edge 43 than trailing edge 44. The ground contact C of golf club 52 is located further from leading edge 55 than trailing edge 56. The ground contact B of golf club 46 is located approximately equidistant between leading edge 49 and trailing edge 50.
The set of golf clubs of the present invention includes progressive sole camber (i.e., front to rear sole curvature) that, in concert with the traditional bounce angle provides desired effective bounce and leading edge height for each club while maintaining the unique position of the ground contact for each of the clubs of the set. Referring to FIG. 4, golf club 40 will be described in greater detail. Golf club 40 includes a face 60 and a body 62 that supports face 60. Face 60 includes a generally planar ball striking surface 61 and a plurality of score lines 63 that extend into face 60 from ball striking surface 61. Body 62 is configured as a cavity-back golf club with perimeter weighting that includes sole 42 and a top line portion 64 and that defines a cavity 65.
Sole 42 is configured to provide desired effective bounce (ε) and leading edge height (L) while maintaining contact point A. For the purposes of this discussion, traditional bounce (β), is the angular relationship between a line extending from the leading edge to the trailing edge and the ground surface. The value of traditional bounce is positive (+) in instances wherein the leading edge is higher than the trailing edge and negative (−) in those where the leading edge is lower than the trailing edge. Effective bounce is the angular relationship between a line extending from the leading edge to the contact point and the ground surface. The leading edge height is the height from the ground to the position on the club head sole that is furthest forward. Each of these measurements is based on a non-compressible, planar ground surface with the golf club oriented with its designed loft and lie angles relative to the ground plane, although the actual ground surface during play may vary based on the conditions of the particular course.
Golf club 40 corresponds to a low-lofted, long iron, such as a 3-iron having a 20.0° loft angle. Golf club 40 has a traditional bounce of −3.0°. Sole 42 is cambered to provide an effective bounce angle of 1.0°-15.0°, preferably 7.5°-8.5°, and more preferably approximately 8.0°. In particular, the camber of sole 42 has a radius of curvature of approximately 1.2-1.8 inches, and more preferably approximately 1.5 inches. Additionally, the leading edge height is set at 0.130-0.140 inches, and more preferably at 0.136 inches. This combination of traditional bounce and sole camber results in the desired ground contact point, effective bounce, and leading edge height.
Referring to FIG. 5, golf club 46 will be described in greater detail. Golf club 46 includes a face 70 and a body 72 that supports face 70. Face 70 includes a generally planar ball striking surface 71 and a plurality of score lines 73 that extend into face 70 from ball striking surface 71. Body 72 is configured as a cavity-back golf club with perimeter weighting that includes sole 48 and a top line portion 74 and that defines a cavity 75.
Golf club 46 corresponds to a mid-lofted, mid-length iron, such as a 6-iron having a 29.0° loft angle. Sole 48 is configured to provide desired effective bounce (ε) and leading edge height (L) while maintaining contact point B. Golf club 46 has a traditional bounce of 0.0°. Next, sole 48 is cambered to provide an effective bounce angle of 1.0°-15.0°, preferably 7.5°-8.5°, and more preferably approximately 8.2°. In particular, the camber of sole 48 has a radius of curvature of approximately 1.5-2.1 inches, and more preferably approximately 1.8 inches. The leading edge height is set at 0.145-0.155 inches, and more preferably at 0.149 inches.
Referring to FIG. 6, golf club 52 will be described in greater detail. Golf club 52 includes a face 80 and a body 82 that supports face 80. Face 80 includes a generally planar ball striking surface 81 and a plurality of score lines 83 that extend into face 80 from ball striking surface 81. Body 82 is configured as a cavity-back golf club with perimeter weighting that includes sole 54 and a top line portion 84 and that defines a cavity 85.
Golf club 52 corresponds to a high-lofted, short iron, such as a 9-iron having a 40.0° loft angle. Sole 54 is configured to provide desired effective bounce (ε) and leading edge height (L) while maintaining contact point B. Golf club 52 has a traditional bounce of 3.0°. The leading edge height is set at 0.165-0.175 inches, and more preferably at 0.171 inches. Next, sole 54 is cambered to provide an effective bounce angle of 1.0°-15.0°, preferably 8.0°-9.0°, and more preferably approximately 8.7°. In particular, the camber of sole 54 has a radius of curvature of approximately 1.8-2.4 inches, and more preferably approximately 2.1 inches.
Based on the exemplary set it should be appreciated that traditional bounce is used as a variable that is manipulated along with sole camber and sole width to arrive at the desired effective bounce and leading edge height. It should also be appreciated that the long-irons need not have the shortest sole width throughout the set.
Although a set of golf clubs including three clubs has been described above, it should be appreciated that a set of iron-type golf clubs may include any number of clubs. It should further be appreciated that the set of clubs may include long-irons, mid-irons, short-irons and wedges, and the clubs may have loft angles ranging from 13°-66°. The features of an exemplary set of iron-type golf clubs are included in the following table:







TABLE 1







Exemplary set of iron-type golf clubs of the present invention











Loft
Traditional
Effective
Leading Edge



Angle (α)
Bounce (β)
Bounce (ε)
Height (L)
Sole Camber


[degrees]
[degrees]
[degrees]
[inch]
[inch]














20.0
−3.0
8.0
0.136
1.5


23.0
−2.0
8.0
0.140
1.6


26.0
−1.0
8.1
0.144
1.7


29.0
0.0
8.2
0.149
1.8


32.5
1.0
8.3
0.155
1.9


36.0
2.0
8.5
0.162
2.0


40.0
3.0
8.7
0.171
2.1


44.0
4.0
8.9
0.180
2.2


49.0
5.0
9.2
0.191
2.3


54.0
6.0
11.2
0.214
1.9


59.0
6.5
9.4
0.206
2.5









The set of iron-type golf clubs of the present invention described in TABLE 1 corresponds to a set of iron-type golf clubs including 3-9 irons, a pitching wedge, a gap wedge, a sand wedge and a lob wedge, all of which have a ground contact that is vertically aligned with the location of the center of gravity of the respective club head. As shown in TABLE 1, the sole camber progressively increases throughout the set of clubs, with the exception of the sand wedge with a 54.0° loft. In that club, although the traditional bounce remains true to the progression of that feature through the set, the effective bounce is increased above the values in the progression of effective bounce through the set. That deviation is incorporated due to the nature of the use of that particular club. In particular, the bounce of a sand wedge is generally increased so that digging into soft sand is prevented. Because of that increased effective bounce and the location of the ground contact, the sole camber is decreased to 1.9 inch to provide those characteristics along with the desired leading edge height. It should be appreciated that the progressive sole camber may also be employed to increase effective bounce in a set that has traditional bounce that is constant, or has an even progression, throughout the set.
Now referring to FIGS. 7 and 8, the ground contact D may include multiple contact locations. For example, club head 10 includes a sole relief 34 that forms a depression on the sole. Sole relief may extend to a location that is vertically aligned with the center of gravity of the club head so that a vertical plane extending in a heel-toe direction and extending through the center of gravity intersects relief 34. Because of the curvature of sole 24 between heel portion 20 and toe portion 22, in such an instance the edges of relief 34 form the lowest portions of sole 24 and as a result ground contact D includes locations on each of a heel edge 35 and toe edge 36 of relief 34. Providing a ground contact having multiple contact locations provides an added benefit of increased stability at address in a heel to toe direction.
Traditionally, a set of iron-type golf clubs are not configured so that the contact point is co-planar with the center of gravity in a vertical plane extending in a heel-toe direction throughout the set. As a result, the golf clubs have a tendency to rotate so that the face angle is either opened or closed at address. In the above described embodiments, the ground contact and the center of gravity are co-planar in a vertical plane extending in a heel-toe direction so that the club heads included throughout the set do not have a tendency to rotate at address. However, it should be appreciated that the ground contact may be located in a spaced relationship relative to a vertical plane extending in a heel-toe direction and extending through the center of gravity. For example, the ground contact may be spaced horizontally either forward or rearward of a vertical plane passing through the center of gravity. For example, the ground contact may be spaced up to 0.500 inches forward or rearward horizontally relative to the center of gravity which would allow the face angle to be designed closed or open.
Back plate 30 includes a multi-piece and multi-material construction, as shown in FIG. 9, that allows for adjustment in the weight of club head 10 and offers improved vibration damping. Back plate 30 includes a weight member 90, a membrane 92 and a cover plate 94. Weight member 90 allows for the addition of weight to the club head. A plurality of weight members 90 are provided having different densities and/or volumes and during assembly a weight member 90 having a desired weight is included to bring the total club head weight to a desired value. Weight member 90 may be constructed from metal, non-metal materials or combinations of metal and non-metal materials. In one example, weight member 90 is constructed of a high density tungsten loaded polyurethane.
Membrane 92 is utilized to couple weight member 90 to cover plate 94 and to provide vibration damping. Membrane 92 includes a hole 96 that has a perimeter shape selected to complement the perimeter shape of weight member 90 and to receive it therein. Membrane 94 may have any contour and may be constructed from metal, non-metal materials or combinations, but preferably is constructed from a material having vibration damping characteristics. In the present embodiment, membrane 92 is constructed from urethane and includes thickened pad portions 98. Membrane 92 may be any shape including curved and/or linear surfaces and membrane 92 may be configured to receive a plurality of weight members 90.
Cover plate 94 covers membrane 92 and weight member 90. Cover plate 94 is coupled to at least a portion of membrane 92 and sandwiches at least a portion of membrane 92 and weight member 90 with the club head body in an assembled golf club head. Cover plate 94 may have any contour. In the present embodiment, cover plate 94 includes holes 99 that receive pads 98 of membrane 96 in the assembled back plate 30 so that pads 98 are exposed. Cover plate 94 may be constructed from metal, non-metal materials or combinations thereof. In the present embodiment, cover plate 94 is constructed from stamped aluminum and provides additional vibration damping.
While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the objectives stated above, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Elements from one embodiment can be incorporated into other embodiments. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments, which would come within the spirit and scope of the present invention.

## Claims

1. A set of iron-type golf clubs, comprising:
a first golf club including a first golf club head having a first loft angle, a first ground contact, and a first sole camber having a first radius of curvature;
a second golf club including a second golf club head having a second loft angle that is greater than the first loft angle, a second ground contact, and a second sole camber having a second radius of curvature that is greater than the first radius of curvature; and
a third golf club including a third golf club head having a third loft angle that is greater than the second loft angle, a third ground contact, and a third sole camber having a third radius of curvature that is greater than the second radius of curvature,
wherein the first golf club, the second golf club and the third golf club have constant horizontal spacing in the face to back direction between the ground contact and the center of gravity through the set and each golf club has an effective bounce of 1.0°-15°, wherein the measurements are based on a non-compressible planar ground surface with said golf clubs oriented with its designed loft and lie angles relative to the ground plane, and wherein said curvature is a face to back curvature.

2. The set of golf clubs of claim 1, wherein the first golf club, the second golf club and the third golf club have an effective bounce of 5°-13°.

3. The set of golf clubs of claim 2, wherein the first golf club, the second golf club and the third golf club have an effective bounce of 7.8°-9.6°.

4. The set of golf clubs of claim 1, wherein a ratio of the second sole camber to the first sole camber is 1.05-1.30.

5. The set of golf clubs of claim 1, wherein a ratio of the third sole camber to the first sole camber is 1.15-1.70.

6. The set of golf clubs of claim 5, wherein the ratio of the third sole camber to the first sole camber is 1.25-1.70.

7. The set of golf clubs of claim 1, wherein a ratio of the first sole camber to the first loft angle is 0.050-0.123 inch/degree.

8. The set of golf clubs of claim 1, wherein a ratio of the second sole camber to the second loft angle is 0.052-0.076 inch/degree.

9. The set of golf clubs of claim 1, wherein a ratio of the third sole camber to the third loft angle is greater than or equal to 0.030 inch/degree.