Abstract:
A golf club head having a face with a plurality of scorelines that have a contour with a continuous curvature is disclosed herein. The face has a thickness that is less than 0.110 inches, and each of the scorelines have a depth that is greater than 0.012 inches. The width of each of the scorelines may be between 0.028 inches and 0.032 inches. Each of the scorelines may have a contour with a first convex section, a concave section and a second convex section. Preferably, the face is composed of a forged titanium material. However, the face and/or club head body may be composed of steel, other metals and composite materials.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
         [0001]    Not Applicable  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0003]    1. Field of the Invention  
           [0004]    The present invention relates to scorelines for a face of a golf club. More specifically, the present invention relates to stress reducing scorelines for a golf club.  
           [0005]    2. Description of the Related Art  
           [0006]    Scorelines have appeared on the faces of golf club heads since at least the 1880s if not earlier. Scorelines usually have a cross-section that is square or slightly curved on the walls perpendicular to the face.  
           [0007]    However, scorelines act as a stress concentrator during impact of the club face with the golf ball. For the most part, this has been of little concern since the thickness of the face has been great enough to absorb the stress concentration caused by the scorelines. However, with the advent of hollow metal woods, stress has become of concern in the face of the club head. As the thickness of club heads become thinner, the need to relieve some of the stress concentration caused by scorelines will present a problem for the golf club industry.  
           [0008]    The Rules of Golf, established and interpreted by the United States Golf Association (“USGA”) and The Royal and Ancient Golf Club of Saint Andrews, set forth certain requirements for scorelines. The requirements for scorelines (grooves) are found in Rule 4 and Appendix II. A complete description of the Rules of Golf are available on the USGA web page at www.usga.org. Rule 4-1e of the Rules of Golf state specific guidelines for scorelines. The impact area of a club face may have a series of grooves with diverging sides and may have a symmetrical cross-section. The width and cross-section must be consistent across the face and along the length of the grooves. Any rounding of the groove edges shall be in the form of a radius which does not exceed 0.020 inches, and the width of the grooves shall not exceed 0.035 inches using the 30 degree method of measurement on file with the USGA. The distance between edges of adjacent grooves must not be less than three times the width of a groove, and not less than 0.0075 inches. The depth of a groove must not exceed 0.020 inches. Punch marks may be used if the area of such punch mark does not exceed 0.0044 square inches. A punch mark must not be closer to an adjacent punch mark than 0.168 inches measured from center to center. The depth of a punch mark must not exceed 0.040 inches. If punch marks are used in combination with grooves, a punch mark must not be closer to a groove than 0.168 inches measured from center to center.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    One aspect of the present invention is a golf club head including a face having a plurality of line scorelines. Each of the plurality of line scorelines has a contour with a continuous curvature. The face has a thickness that is less than 0.110 inches.  
           [0010]    The contour of each of the plurality of line scorelines may have a first convex section, a concave section, and a second convex section. The greatest depth of each of the plurality of line scorelines may be less than 0.008 inches. The face may include a heel portion, a toe portion and a center portion juxtaposed by the heel portion and the toe portion, wherein the center portion is divided into a crown half and a sole half, and the crown half has an absence of line scorelines. The heel portion and the toe portion of the face may have an equal number of line scorelines. The vertical distance between each of the plurality of line scorelines may be equal. The width of each of the plurality of scorelines may be between 0.028 and 0.032 inches. The face may have a thickness in the range of 0.064 to 0.110 inches. The golf club head may be a metal wood and may be composed of a material selected from the group consisting of a forged titanium alloy material, steel, composite materials, and mixtures thereof. Alternatively, the golf club head may be an iron or a putter with a relatively thin face having the plurality of line scorelines thereon.  
           [0011]    Another aspect of the present invention is a golf club head including a face having a plurality of line scorelines. Each of the plurality of line scorelines has a depth less than 0.012 inches and a contour including a first convex section, a concave section and a second convex section, with the face having a thickness that is less than 0.110 inches.  
           [0012]    Yet another aspect of the present invention is a golf club head including a face having a plurality of line scorelines. Each of the plurality of line scorelines has a contour including a first convex section, a concave section and a second convex section, with each of the plurality of line scorelines having a depth that is greater than twenty percent of the thickness of the face. Thus, the depth of each of the line scorelines is substantial compared to the thickness of the face.  
           [0013]    Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a front plan view of the golf club head of the present invention.  
         [0015]    [0015]FIG. 1A is a front plan view of an alternative embodiment of the golf club head of the present invention.  
         [0016]    [0016]FIG. 1B is a perspective view of an further alternative embodiment of the golf club head of the present invention.  
         [0017]    [0017]FIG. 2 is a cross-section view of FIG. 1 along lie  2 - 2 .  
         [0018]    [0018]FIG. 3 is an enlarged view of circle  3  of FIG. 2 to illustrate the cross-section of a line scoreline of the golf club head of the present invention.  
         [0019]    [0019]FIG. 4 is an enlarged view of circle  4  of FIG. 2 to illustrate the cross-section of a dot scoreline of the golf club head of the present invention.  
         [0020]    [0020]FIG. 5 is a front plan view of the preferred embodiment of the present invention, as illustrated in FIG. 1, illustrating the partitioning of the face plate of the golf club head of the present invention.  
         [0021]    [0021]FIG. 6 is an isolated view of the face plate the golf club head of the present invention illustrating the regions of thickness of the face plate.  
         [0022]    [0022]FIG. 7 is a cross-sectional view of a scoreline of the prior art.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    As shown in FIGS. 1, 1A and  1 B, a golf club is generally designated  40 . The golf club  40  has a golf club head  42  with a body  44  and a hollow interior, not shown. Engaging the club head  42  is a shaft  48  that has a grip  50 , not shown, at a butt end and is inserted into a hosel  54  at a tip end. An O-ring  58  may encircle the shaft  48  at an aperture  59  to the hosel  54 .  
         [0024]    The body  44  of the club head  42  is generally composed of three sections, a face member  60 , a crown  62  and a sole  64 . The club head  42  may also be partitioned into a heel section  66  nearest the shaft  48 , a toe section  68  opposite the heel section  66 , and a rear section  70  opposite the face member  60 .  
         [0025]    The face member  60  is generally composed of a single piece of metal, and is preferably composed of a forged metal material. More preferably, the forged metal material is a forged titanium material. However, those skilled in the relevant art will recognize that other materials such as composite materials, alloys, steels and the like may be utilized without departing from the scope and spirit of the present invention. The face member  60  generally includes a face plate  72  and a face extension  74  extending laterally inward from the perimeter of the face plate  72 . The face plate  72  has a plurality of line scorelines  75  thereon, and a plurality of dot scorelines  77 . An alternative embodiment of the face plate  72  is illustrated in FIG. 1A which has a different scoreline pattern. The face extension  74  generally includes an upper lateral extension  76  and a lower lateral extension  78 . A more detailed explanation of the face member  60  is set forth in copending U.S. patent application No. 09______, filed on an even date herewith, entitled A Golf Club Head With A Face Composed Of A Forged Material, and incorporated by reference in its entirety.  
         [0026]    [0026]FIG. 2 is a cross-sectional view of the face plate  72  of the present invention. Circles  3  and  4  correspond to one of the line scorelines  75  and one of the dot scorelines  77 , respectively. As shown in FIG. 3, each of the line scorelines  75  has a contour  80  with a first convex portion  82 , a concave portion  84  and a second convex portion  86 . In a preferred embodiment, the radius of the concave portion  84  is 0.0156 inches. In a preferred embodiment, the radius of each of the first and second convex portions  82  and  86  is 0.002 inches. The depth “D” of each of the plurality of line scorelines  75  preferably ranges from 0.008 inches to 0.012 inches, and is most preferably 0.010 inches. The width “W” of each of the plurality of line scorelines  75  is preferably 0.030 inches.  
         [0027]    As shown in FIG. 4, each of the dot scorelines  77  has a contour  90  with a first convex portion  92 , a straight portion  94  and a second convex portion  96 . In a preferred embodiment, the radius of each of the first and second convex portions  92  and  96  is 0.004 inches. The depth “D” of each of the plurality of dot scorelines  77  preferably ranges from 0.006 inches to 0.008 inches, and is most preferably 0.007 inches. The width “W” of each of the plurality of dot scorelines  77  is preferably 0.029 inches.  
         [0028]    The contoured scorelines  75  assist in relieving stress on the face plate  72  since scorelines in general have the effect of concentrating stress during impact with a golf ball. As shown in FIG. 7, the prior art scorelines  202  on a face  200  have relied on the thickness of the face to use a squarer cross-section for the scorelines  200 . In face plates  72  that are relatively thin, the concentration of stress could lead to failure of the face plate  72 . In one embodiment of the present invention, the face plate thickness ranges from 0.06 inches to 0.103 inches. In this thickness range, the contour  80  of each of the plurality of line scorelines  75  assist in reducing the concentration of stress in the face plate  72  during impact with a golf ball.  
         [0029]    Additionally, mapping of the face plate  72  for the probable impact locations to determine the highest stress areas resulted in the absence of scorelines in the preferred embodiment of the present invention, as shown in FIG. 5. The face plate  72  is divided into a crown half  126  and a sole half  128  by a horizontal line  120 . The face plate  72  is further partitioned into a toe portion  130 , a center portion  132  and a heel portion  134  by two vertically angled lines  122  and  124  which lie on the two angled columns of dot scorelines  77 . Thus, center portion  132  of the crown half  126  has an absence of scorelines since this area has the highest probability of impacts with a golf ball.  
         [0030]    [0030]FIG. 6 illustrates the variation in the thickness of the face plate  72  for one embodiment of the present invention. The face plate  72  is partitioned into elliptical regions, each having a different thickness. A central elliptical region  102  preferably has the greatest thickness that ranges from 0.110 inches to 0.091 inches, preferably from 0.099 inches to 0.093 inches, and is most preferably 0.095 inches. A first concentric region  104  preferably has the next greatest thickness that ranges from 0.097 inches to 0.082 inches, preferably from 0.090 inches to 0.082 inches, and is most preferably 0.086 inches. A second concentric region  106  preferably has the next greatest thickness that ranges from 0.094 inches to 0.070 inches, preferably from 0.078 inches to 0.070 inches, and is most preferably 0.074 inches. A third concentric region  108  preferably has the next greatest thickness that ranges from 0.090 inches to 0.07 inches. A periphery region  110  preferably has the next greatest thickness that ranges from 0.069 inches to 0.061 inches. The variation in the thickness of the face plate  72  allows for the greatest thickness to be distributed in the center  111  of the face plate  72  thereby enhancing the compliance of the face plate  72  during impact with a golf ball.  
         [0031]    Additionally, the face plate  72  of the present invention has a smaller aspect ratio than face plates of the prior art. The aspect ratio as used herein is defined as the width, “w”, of the face divided by the height, “h”, of the face, as shown in FIG. 1A. In conventional golf club heads, the aspect ratio is usually much greater than 1. For example, the original GREAT BIG BERTHA® driver from Callaway Golf Company had an aspect ratio of 1.9. The face of the present invention has an aspect ratio that is no greater than 1.7. The aspect ratio of the present invention preferably ranges from 1.0 to 1.7, and is most preferably 1.3. The face of the present invention is more circular than faces of the prior art. The face area of the face plate  72  of the present invention ranges from 4.95 square inches to 5.1 square inches.  
         [0032]    The aspect ratio, area and thickness of the face plate  72  of the preferred embodiment of the present invention all increase the concentration of stress in the line scorelines  75 . The contour  80  of each of the plurality of line scorelines  75  relieves some of this stress providing the face plate  72  with greater durability. A more detailed explanation of the aspect ratio, area and thickness of the face plate  72  of the preferred embodiment of present invention is set forth in the previously mentioned co-pending U.S. patent application No. 09/______ , filed on an even date herewith, entitled A Golf Club Head With A Face Composed Of A Forged Material.  
         [0033]    Although the present invention has been described in reference to a wood golf club head, those skilled in the relevant art will readily recognize that the scorelines of the present invention may be utilized with an iron or putter golf club head without departing from the scope or spirit of the present invention.  
         [0034]    From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.