Abstract:
A golf club head has a cavity for receiving a face insert. A first face insert, which is disposed in the cavity, has a front surface that is contoured. A second face insert composed of multiple rod elements is disposed in the cavity on top of the first face insert so that the rod elements are supported by the contoured front surface of the first face insert. Because the first face insert supporting the rod elements is contoured, the individual rod elements are of different lengths and, therefore, exhibit different dynamic responses when striking a golf ball, even when the rod elements are made of the same material.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to golf equipment and, in particular, to golf club heads. 
   In order to improve the “feel” of golf clubs, especially putters, golf manufactures have frequently provided a face insert on the front face of the club head. Early golf clubs had face inserts made of cork, wood, rubber, or gutta-percha. More recent examples of golf clubs having face inserts include U.S. Pat. No. 5,575,472 to Magerman et al which discloses a putter head with a recess into which is poured a polymer resin that is cured and subsequently milled to produce the putter head. U.S. Pat. No. 5,524,331 to Pond discloses a metal club head with a cast graphite epoxy composite insert, and U.S. Pat. No. 5,458,332 to Fisher discloses a putter head having a polyurethane face insert with specific hardness and resiliency properties. 
   U.S. Pat. No. 5,807,190 to Krumme et al. discloses a club head in which a face insert is actually composed of many small rods arranged in a closely packed array. According to the Krumme patent, the use of individual rods to form the front face allows the properties of the front face to vary in any pattern over the impact area simply by varying the materials out of which the individual rods are made. Use of multiple materials within the array of rods would, however, render such a golf club head non-conforming since Rule  5 ( b ) of Appendix II of the U.S. Golf Association requires that the whole of the impact area of a golf club head must be of the same material. Accordingly, what is needed is a golf club head having a face insert composed of individual rod elements in which the impact response properties of the individual rod elements can be varied without varying the material forming the rod elements. 
   SUMMARY OF THE INVENTION 
   The present invention comprises a golf club head the front face of which has a cavity for receiving a face insert. According to an illustrative embodiment, a first face insert, which is disposed in the cavity, has a front surface that is contoured. A second face insert composed of multiple rod elements is disposed in the cavity on top of the first face insert so that the rod elements are supported by the contoured front surface of the first face insert. The second face insert is finished flat to form a striking surface on the front face. Because the first face insert supporting the rod elements is contoured, however, the individual rod elements are of different lengths and, therefore, exhibit different dynamic responses when striking a golf ball, even when the rod elements are made of the same material. In alternative embodiments, the first face insert may be formed into an inherently compliant structure and/or made of a compliant material such as an elastomer to further increase the variation of dynamic response across the front face. 

   
     DESCRIPTION OF THE DRAWINGS 
     The present invention will be better understood from a reading of the following detailed description, taken in conjunction with the accompanying drawing figures in which like references designate like elements, and in which: 
       FIG. 1  is a front perspective view of a golf club incorporating features of the present invention; 
       FIG. 2  is a cross-sectional view of the golf club of  FIG. 1  taken along line  2 - 2 ; 
       FIG. 3  is a cross-sectional view of an alternative embodiment of a golf club incorporating features of the present invention; 
       FIG. 4  is a cross-sectional view of another alternative embodiment of a golf club incorporating features of the present invention; 
       FIG. 5  is a cross-sectional view of another alternative embodiment of a golf club incorporating features of the present invention; 
       FIG. 6  is a cross-sectional view of yet another alternative embodiment of a golf club incorporating features of the present invention; and 
       FIG. 7  is a cross-sectional view of yet another alternative embodiment of a golf club incorporating features of the present invention. 
   

   DESCRIPTION OF THE INVENTION 
   With reference to  FIGS. 1 and 2 , a golf club  10 , preferably a golf putter, comprises a club head body  12  attached to a golf club shaft  14 . Typically the club head body is made of a suitable metal such as steel formed by an investment casting process, however other metal materials such as titanium, aluminum, tungsten, brass, bronze and beryllium copper may be used to form club head body  12 . Those skilled in the art will recognize also that the club head body  12  may be made of other metallic or non-metallic materials without departing from the scope of the present invention. Club head body  12  has a front face  16 , a rear surface  18 , a heel end  20  and a toe end  22 , as well as a top rail  24  and sole  26 . In the illustrative embodiment, club head body  12  is formed with a cavity  28  that extends from the front face  16  toward the rear surface  18  and is defined by side wall  30  and bottom wall  32 . As shown most clearly in  FIG. 2 , a first face insert  34  is disposed within cavity  28  such that its back surface  36  faces bottom wall  32  of cavity  28  and its lateral wall  38  abuts side wall  30  of cavity  28 . First face insert  34  may be made from a rigid metallic material such as steel, titanium, aluminum, tungsten, copper and the like, or a rigid non-metallic material such as ceramic, graphite-epoxy or other composite material. Those skilled in the art, however, will recognize that first face insert  34  may be made of other materials without departing from the scope and spirit of the present invention. 
   A second face insert  40  is also disposed within cavity  28  atop first face insert  34 . Second face insert  40  comprises a plurality of individual rod elements  42 . Each of rod elements  42  has substantially the same geometry, except for the individual lengths. Accordingly, the individual rod elements are not separately described. Rod elements  42  are packed together in an array such that each side surface  44  of a rod element  42  is in contact with the side surface  44  of the adjacent rod element  42 . Second face insert  40  is positioned in cavity  28  such that a bottom wall  46  of each of the rod elements  42  is supported by a front surface  48  of first face insert  34 . Exposed end walls  50  of the rod elements  42  are finished flat to form the striking surface of front face  16  of club head body  12 . 
   Because the front surface  48  of first face insert  34  is contoured so that the thickest portion of face insert  34  is proximal a center region  52  of first face insert  34 , the rod elements  42  of second face insert  40  are shorter over center region  52  of first face insert  34  and are longer over the perimeter region  54  of first face insert  34 . Accordingly, second face insert  40  will have a different dynamic response in the center region  52  than it will in the perimeter region  54 . As noted herein before, in the illustrative embodiment of  FIG. 2 , first face insert  34  is composed of a rigid material so that the variation in dynamic response across the face  56  of second face insert  40  is dominated by the difference in response of the individual rod elements  42 . Alternatively, however, first face insert  34  may be composed of an elastomeric material such as polyurethane to provide a compliant support for the individual rod elements  42  of second face insert  40 . In this case, the dynamic response across the face  56  of second face insert  40  would be a composite of the resiliency and damping properties of the elastomeric first face insert  34  and the response of the rod elements  42 . 
   First face insert  34  may be cast in place but is preferably cast or molded separately and pressed or bonded in place within cavity  28 . Second face insert  40  may be formed of individual rods of circular cross section (not shown) but preferably comprises the plurality of rod elements  42  having a hexagonal cross section arranged in a hexagonal close-packed array surrounded by an epoxy binder  60  that holds the rod elements  42  in place as shown in  FIG. 1 . 
   With reference to  FIG. 3 , an alternative embodiment of a golf club head incorporating features of the present invention, comprises a club head body  312  having a front face  316 , a rear surface  318 , a heel end  320  and a toe end  322 . A cavity  328  extends from the front face  316  toward the rear surface  318  and terminates in a bottom wall  332 . A first face insert  334  is disposed within cavity  328  such that the back surface  336  of first face insert  334  faces bottom wall  332  of cavity  328 . The front surface  348  is contoured such that first face insert  334  is thinner proximal center region  352  and is thicker in perimeter region  354 . Second face insert  340 , which is composed of a plurality of rod elements  342  is disposed in cavity  328  such that the bottom end walls  346  of rod elements  342  are supported by front surface  348  of first face insert  334 . As with the illustrative embodiment of  FIG. 2 , first face insert  334  can be made of any rigid material, in which case the dynamic response of the face is dominated by the difference between the lengths of the individual rod elements of second face insert  340 . Additionally, if first face insert  334  is made of a material that is denser than the material out of which club head body  312  is composed, the distribution of material in first face insert  334  can increase the heel toe weighting of the club head without the use of visible heel and toe weights. Alternatively, as with the illustrative embodiment of  FIG. 2 , first face insert  334  may be composed of an elastomeric material, in which case the variation in dynamic response across the face  356  of second face insert  340  will be a composite of the variation in dynamic response of the individual rod elements as well as the response of the compliant substrate of first face insert  334 . 
   With reference to  FIG. 4 , an alternative embodiment of a golf club head incorporating features of the present invention, comprises a club head body  412  having a front face  416 , a rear surface  418 , a heel end  420  and a toe end  422 . A cavity  428  extends from the front face  416  toward the rear surface  418  and terminates in a bottom wall  432 . A first face insert  434  is disposed within cavity  428  such that the back surface  436  of first face insert  434  faces bottom wall  432  of cavity  428 . The front surface  448  is smoothly contoured such that first face insert  434  is thinner proximal center region  452  and becomes gradually thicker in perimeter region  454 . Second face insert  440 , which is composed of a plurality of rod elements  442  is disposed in cavity  428  such that the bottom end walls  446  of rod elements  442  are supported by front surface  448  of first face insert  434 . As with the illustrative embodiment of  FIG. 2 , first face insert  434  can be made of any rigid material, in which case the dynamic response of the face is dominated by the difference between the lengths of the individual rod elements of second face insert  440 . Additionally, if first face insert  434  is made of a material that is denser than the material out of which club head body  412  is composed, the distribution of material in first face insert  434  can increase the heel toe weighting of the club head without the use of visible heel and toe weights. Alternatively, as with the illustrative embodiment of  FIG. 2 , first face insert  434  may be composed of an elastomeric material, in which case the variation in dynamic response across the face  456  of second face insert  440  will be a composite of the variation in dynamic response of the individual rod elements as well as the response of the compliant substrate of first face insert  434 . 
   With reference to  FIG. 5 , an alternative embodiment of a golf club head incorporating features of the present invention, comprises a club head body  512  having a front face  516 , a rear surface  518 , a heel end  520  and a toe end  522 . A first face insert  534  is disposed within cavity  528  such that the lower surface  536  of first face insert  534  faces bottom surface  532  of cavity  528 . As with the illustrative embodiment of  FIG. 2 , second face insert  540  is disposed in cavity  528  such that the bottom end walls  546  of rod elements  542  are supported by a front surface  548  of first face insert  534 . As with the illustrative embodiment of  FIG. 2 , first face insert  534  can be made of a rigid or elastomeric material depending upon the desired club head response. Back surface  536  of first face insert  534  is also contoured to provide a back cavity  550  in first face insert  534 . Rear surface  518  of club head body  512  includes an aperture  552  that opens into cavity  550  which permits cavity  550  to act as an air-dashpot to further tailor the response characteristics of the face  556  of second face insert  540  when striking a golf ball. Alternatively, a third material, such as a highly viscous silicone gel may be injected into back cavity  550  to provide a different response characteristic. 
   With reference to  FIG. 6 , another alternative embodiment of a golf club head incorporating features of the present invention comprises a club head body  612  having a cavity  628  formed therein. A first face insert  634  is disposed within the cavity  628 . In the embodiment of  FIG. 6 , both the front surface  648  and back surface  636  are smoothly contoured to form an arch-like structure capable of substantial deflection without permanent deformation. Accordingly, the rod elements  642  that comprise second face insert  640  are able to “float” a substantial amount during the impact event with a golf ball and return to their pre-impact positions. 
   With reference to  FIG. 7 , yet another alternative embodiment of a golf club head incorporating features of the present invention comprises a club head body  712  having a front face  716 , a rear surface  718 , a heel end  720  and a toe end  722 . A cavity  728  extends from the front face  716  toward the rear surface  718  and terminates in a bottom wall  732 . First face insert  734  is disposed such that back surface  736  faces bottom wall  732  of cavity  728 . Second face insert  740  which is composed of a plurality of rod elements is disposed in cavity  728  such that the rod elements are supported by front surface  748  of first face insert  734 . A third face insert  760  is disposed in cavity  728  between the back surface  736  of first face insert  734  and bottom wall  732  of cavity  728 . Third face insert  760  is preferably made of an elastomeric material the hardness of which has a lower durometer value than the hardness of first face insert  734 . The combination of first face insert  734  and third face insert  760  provides a relatively non-compliant support for the rod elements  742  of first face insert  740  while providing a highly compliant support structure for the entirety of first face insert  740 . In this case, the dynamic response across the face  756  of second face insert  740  is a composite of the resiliency and damping properties of the rod elements  742  the relatively non-complaint first face insert  734  and the highly complaint third face insert  760 . 
   Although certain illustrative embodiments and methods have been disclosed herein, it will be apparent from the foregoing disclosure to those skilled in the art that variations and modifications of such embodiments and methods may be made without departing from the spirit and scope of the invention. Accordingly, it is intended that the invention should be limited only to extent required by the appended claims and the rules and principals of applicable law.