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 at address and during a swing.
The sole configuration of iron-type golf clubs is particularly important due to the wide variety of surfaces that the sole contacts and because if configured properly, the behavior the sole 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.