Patent Publication Number: US-9901793-B2

Title: Golf club head

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a golf club head. 
     Description of the Related Art 
     To improve the performance of a golf club head, various structures have been proposed. For example, U.S. Pat. No. 6,558,271 discloses a golf club head that has a hollow structure incorporating a skeleton so as to improve the degree of freedom for the position of center of gravity and the like. For example, each of U.S. Pat. Nos. 7,140,977 and 8,602,912 and Japanese Patent No. 5438124 discloses a golf club head having a structure that reinforces the central portion of the face portion. Each of Japanese Patent Nos. 4608437 and 4608426 discloses a golf club head that includes an interchangeable part so as to allow a user to select desired characteristics. Each of Japanese Patent Nos. 4608437 and 4608426 discloses an interchangeable part that promotes attenuation of vibration in the face portion at impact. Japanese Patent Laid-Open No. 2012-525214 discloses a golf club head having a structure that reinforces the central portion of the face portion, and particularly, a structure capable of adjusting the rigidity of the central portion. 
     The rigidity distribution of the face portion affects characteristics of a golf club head such as distance performance and a hitting feel. However, the degree of effects changes depending on the capability and need of a golfer. Hence, it is preferable to allow the golfer to select desired characteristics. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a golf club head that allows a golfer to change the rigidity distribution of a face portion. 
     According to an aspect of the present invention, there is provided a golf club head comprising: a face portion; a plurality of interchangeable members; and a plurality of attachment portions, wherein the plurality of interchangeable members include at least a first interchangeable member, and a second interchangeable member, the plurality of attachment portions include at least a first attachment portion from which the first interchangeable member is detachable, and a second attachment portion disposed at a portion different from the first attachment portion, from which the second interchangeable member is detachable, the first interchangeable member is detachable from the second attachment portion, the second interchangeable member is detachable from the first attachment portion, the first interchangeable member is a reinforcing member that abuts against a rear surface of the face portion and restricts deformation of an abutment portion when the first interchangeable member is attached to the first attachment portion, and the second interchangeable member is a member that does not abut against the rear surface of the face portion when the second interchangeable member is attached to the first attachment portion. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of a golf club head according to an embodiment of the present invention; 
         FIG. 1B  is a view of the golf club head shown in  FIG. 1A  which is viewed from the side of a sole portion; 
         FIGS. 2A and 2B  are sectional views taken along a line I-I in  FIG. 1A ; 
         FIGS. 3A and 3B  are explanatory views of an example of the position of an abutment portion; and 
         FIGS. 4A to 4C  are explanatory views of other examples. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     First Embodiment 
       FIG. 1A  is a perspective view of a golf club head  10  according to an embodiment of the present invention.  FIG. 1B  is a view of the golf club head  10  viewed from the side of a sole portion  13 . 
     The golf club head  10  is hollow and has peripheral walls formed from a face portion  11 , a crown portion  12 , the sole portion  13 , and a side portion  14 . The surface (front surface) of the face portion  11  forms a face (striking face). A bulge and a roll can be formed on the face. The crown portion  12  forms the upper portion of the golf club head  10 . The sole portion  13  forms the bottom portion of the golf club head  10 . The side portion  14  forms the portion between the sole portion  13  and the crown portion  12 . The golf club head  10  includes a hosel portion  15  to which a shaft is attached. 
     An arrow d 1  in  FIG. 1A  indicates the face-back direction, and an arrow d 2  indicates the toe-heel direction. The face-back direction normally corresponds to a target line direction (target direction of a shot). The toe-heel direction is the direction in which the toe-side end and the heel-side end of the sole portion  13  are connected. The vertical direction of the face portion  11  is defined based on the golf club head grounded in accordance with a predetermined lie angle. In this embodiment, the vertical direction is the direction of sole portion  13 -crown portion  12 . 
     The golf club head  10  is a golf club head for a driver. However, the present invention is applicable to golf club heads of other types such as wood type golf club heads including a fairway wood other than drivers. 
     The golf club head  10  can be made of a metal material. Examples of the metal material are a titanium-based metal (for example, titanium alloy 6Al—4V—Ti), stainless steel, and a copper alloy such as beryllium copper. 
     The golf club head  10  can be assembled by joining a plurality of parts. For example, the golf club head  10  can be formed from a main body member and a face member. The main body member forms the peripheral portions including the crown portion  12 , the sole portion  13 , the side portion  14 , and the face portion  11 . An opening is formed at part of the portion corresponding to the face portion  11 . The face member is joined to the opening of the main body member. 
     The golf club head  10  includes attachment portions  16  and  17 . In this embodiment, the attachment portion  16  is disposed in the sole portion  13 . More specifically, the sole portion  13  includes a concave portion  13   a  that is recessed with respect to the periphery, and the attachment portion  16  is formed in the wall portion of the concave portion  13   a  and located inside the golf club head  10 . In addition, the attachment portion  16  is located at the central portion of the sole portion  13  concerning the direction d 2 , and disposed at a position close to the side of the face portion  11  concerning the direction d 1 . 
     The attachment portion  17  is disposed at a position different from the attachment portion  16 . In this embodiment, the attachment portion  17  is disposed in the side portion  14  on the back side, and disposed at a position close to the back side concerning the direction d 1 . For this reason, the attachment portions  16  and  17  are disposed at portions spaced apart from each other in the direction d 1 . The attachment portion  17  is disposed at a position close to the heel side concerning the direction d 2 . For this reason, the attachment portions  16  and  17  are disposed at portions spaced apart from each other in the direction d 2  as well. 
     In the embodiment, the attachment portions  16  and  17  are threaded holes having the same diameter and same pitch. The attachment portion  16  is formed such that a center line d 3  crosses the face portion  11 . The attachment portion  17  is formed such that a center line d 4  is closer to the direction d 2  than the direction d 1 . 
     The golf club head  10  includes interchangeable members  18  and  19 . In this embodiment, the interchangeable member  18  is a screw member integrally including a screw shaft  18   a  and a head portion  18   b . In this embodiment, the interchangeable member  19  is a screw member integrally including a screw shaft  19   a  and a head portion  19   b.    
     Each of the head portions  18   b  and  19   b  has a hole that has a closed bottom and engages with a tool such as a hexagonal wrench. Each of the screw shafts  18   a  and  19   a  has a shaft diameter and a screw thread pitch to threadably engage with the attachment portions  16  and  17 . Hence, the interchangeable member  18  can freely selectively be detached from either of the attachment portions  16  and  17 . Similarly, the interchangeable member  19  can freely selectively be detached from either of the attachment portions  16  and  17 . As described above, although the attachment portion  16  is located inside the golf club head  10 , the concave portion  13   a  makes it relatively easy to detach the interchangeable member  18  or  19 . The attachment portion  17  opens to the side portion  14 . This also makes it relatively easy to detach the interchangeable member  18  or  19 . 
     In this embodiment, the interchangeable members  18  and  19  have the same structure except the total length. The total length of the interchangeable member  18  is L 1 , and the total length of the interchangeable member  19  is L 2 , which hold a relationship given by L 1 &gt;L 2 . In this embodiment, the difference between the total lengths L 1  and L 2  is mainly caused by the length difference between the screw shafts  18   a  and  19   a . The head portions  18   b  and  19   b  have the same shape. 
     In this embodiment, the interchangeable members  18  and  19  are solid metal members integrally made of metal materials having the same specific gravity. Examples of the metal material are titanium, titanium alloy, aluminum, aluminum alloy, tungsten, tungsten alloy, and stainless steel. As already described, the interchangeable members  18  and  19  have different total lengths and therefore have different weights. In this embodiment, the interchangeable member  18  is longer and therefore heavier than the interchangeable member  19 . 
     In the golf club head  10  according to this embodiment, the attachment positions of the interchangeable members  18  and  19  can be selected. In the first attachment mode, the interchangeable member  18  is attached to the attachment portion  16 , and the interchangeable member  19  is attached to the attachment portion  17 . In the second attachment mode, the interchangeable member  18  is attached to the attachment portion  17 , and the interchangeable member  19  is attached to the attachment portion  16 . 
     The difference between the attachment modes will be described below with reference to  FIGS. 2A and 2B .  FIGS. 2A and 2B  are sectional views taken along a line I-I in  FIG. 1A .  FIG. 2A  is a sectional view in the first attachment mode.  FIG. 2B  is a sectional view in the second attachment mode. 
     As shown in  FIG. 2A , in the first attachment mode, the distal end of the interchangeable member  18  (the distal end of the screw shaft  18   a ) abuts against the rear surface of the face portion  11 . In other words, the total length L 1  of the interchangeable member  18  (particularly the length of the screw shaft  18   a ) and the position of the attachment portion  16  are designed such that the distal end of the interchangeable member  18  abuts against the rear surface of the face portion  11 . 
     When the distal end of the screw shaft  18   a  abuts against the rear surface of the face portion  11 , deformation of the face portion  11  at an abutment portion P is restricted. That is, the interchangeable member  18  functions as a reinforcing member that locally restricts deformation of the face portion  11 . In this embodiment, the distal end of the screw shaft  18   a  is tapered and comes into point contact with the rear surface of the face portion  11 . This can suppress excessive restriction on deformation of the face portion  11 . The distal end of the screw shaft  18   a  may be in contact so as not to press the rear surface of the face portion  11  or so as to press the rear surface to the face side in the natural state. The degree of pressing may be adjustable by the degree of fastening of the screw shaft  18   a  in the attachment portion  16 . In the maximum fastening level, the distal end of the screw shaft  18   a  may slightly displace the rear surface of the face portion  11  to the face side. 
     In this embodiment, the abutment portion P is located at the central portion of the face portion  11  concerning the direction d 2  or on the lower side of the face portion  11  concerning the vertical direction. An example of the position of the abutment portion P will be described in detail with reference to  FIGS. 3A and 3B . 
     Referring to  FIG. 3A , a plane S 1  is a virtual vertical plane that passes through a geometric center Fc of the face portion  11  and is perpendicular to the ground surface and the toe-heel direction when the golf club head  10  is grounded at a predetermined lie angle and a predetermined loft angle. Note that the lie angle is made by the ground surface and an axis L 11  of a shaft mounted on the hosel portion  15 , as indicated by an angle θ 1  in  FIG. 3A . The loft angle is made by the face portion  11  and a plane perpendicular to the ground surface, as indicated by an angle θ 2  in  FIG. 3B . 
     Let FP 1  and FP 2  be the upper and lower end positions of the face portion  11  crossing the plane S 1 , respectively. A height difference H between the positions FP 1  and FP 2  is defined as the height of the face portion  11 . 
     The face portion  11  is virtually divided into three areas R 1  to R 3  in accordance with the height. The lower area R 3  is, for example, an area of H×0.3 from the lower end of the face portion  11 . The central area R 2  is, for example, an area of H×0.7 from the upper end of the lower area R 3 . The upper area R 1  is, for example, an area from the upper end of the central area R 2  to the upper end of the face portion  11 . They are expressed by numerical values as lower area R 3 ≦H×0.3, H×0.3&lt;central area R 2 ≦H×0.7, and upper area R 1 &gt;H×0.7. The abutment portion P can be set in the lower area R 3 . 
     Referring to  FIG. 2B , in the second attachment mode, the distal end of the interchangeable member  19  (the distal end of the screw shaft  19   a ) does not abut against the rear surface of the face portion  11 . In other words, the total length L 2  of the interchangeable member  19  (particularly the length of the screw shaft  19   a ) and the position of the attachment portion  16  are designed such that the distal end of the interchangeable member  19  is spaced apart from the rear surface of the face portion  11  so as not to abut against the rear surface. In this embodiment, the presence/absence of abutment against the rear surface of the face portion  11  is controlled by the total lengths of the interchangeable members  18  and  19 , and the presence/absence of abutment against the rear surface of the face portion  11  can be switched by a relatively simple structure. 
     A change in the characteristics of the golf club head  10  between the first attachment mode and the second attachment mode will be explained. In this embodiment, two types of characteristics simultaneously change between the two attachment modes. One of the characteristics is the rigidity distribution of the face portion  11 , and the remaining one is the position of center of gravity. 
     In the first attachment mode, deformation of the abutment portion P is restricted. As for the rigidity distribution of the face portion  11 , the rigidity is relatively low from the central portion to the upper portion and relatively high at the lower portion. That is, at impact, since the upper portion of the face portion  11  readily flexes to the back side, the launch angle of the shot tends to be high. Focusing on the center of gravity, the attachment portions  16  and  17  are spaced part from each other in the direction d 1 , and the interchangeable member  18  is heavier than the interchangeable member  19 . Hence, the position of center of gravity of the golf club head  10  is located relatively on the side of the face portion  11 . Hence, the back spin rate of the shot tends to be suppressed. For the above-described reasons, the maximum distance performance of a shot becomes relatively high in the first attachment mode. 
     In the second attachment mode, deformation of the face portion  11  is not restricted by the interchangeable members  18  and  19 . Hence, as for the rigidity distribution of the face portion  11 , the rigidity is not relatively high at the lower portion, unlike the first attachment mode. That is, the area having a high repulsion is wider than in the first attachment mode. Focusing on the center of gravity, the attachment portions  16  and  17  are spaced part from each other in the direction d 1 , and the interchangeable member  18  that is relatively heavy is located on the back side. Hence, the gravity depth is deeper, and the moment of inertia of the golf club head  10  is larger than in the first attachment mode. For the above-described reasons, in the second attachment mode, the variation in the distance of a shot with respect to the variation in the impact point becomes relatively small. 
     As described above, in this embodiment, a golfer can change the rigidity distribution or the position of center of gravity of the face portion  11  by changing the combinations of the interchangeable members  18  and  19  and the attachment portions  16  and  17 . The rigidity distribution and the position of center of gravity are not changed irrelevantly. That is, in the first attachment mode, a rigidity distribution and a position of center of gravity which are suitable for improving the maximum distance performance are obtained. In the second attachment mode, a rigidity distribution and a position of center of gravity which are suitable for suppressing a variation in the distance performance are obtained. Hence, the golfer can easily understand the difference in the characteristics of the golf club head  10  caused by the difference in the attachment position. 
     Second Embodiment 
     The present invention is also applicable to an iron type golf club head.  FIG. 4A  is a perspective view of a golf club head  100  according to another embodiment of the present invention. Arrows d 1  and d 2  indicate the face-back direction and the toe-heel direction, respectively, as in the first embodiment. 
     The golf club head  100  includes a face portion  101 , a back portion  102 , a sole portion  103 , a side portion  104 , and a hosel portion  105 . 
     The surface (front surface) of the face portion  101  forms a face (striking face). Score lines can be formed in the face. The back portion  102  is spaced apart from the face portion  101  in the direction d 1  (face-back direction) and forms the rear portion of the golf club head  100 . The sole portion  103  forms the bottom portion of the golf club head  100  and connects the face portion  101  and the back portion  102 . The side portion  104  forms the side portion of the golf club head  100 . 
     The golf club head  100  can be formed from a single part or assembled by joining a plurality of parts. When joining a plurality of parts, for example, the golf club head  100  can be formed from a main body member and a face member. The main body member forms portions other than the face portion  101 , and the face member is joined to the main body member to form the face portion  101 . 
     The golf club head  100  includes attachment portions  106  and  107 . In this embodiment, the attachment portion  106  is disposed in the back portion  102 . More specifically, the attachment portion  106  is located at the central portion of the back portion  102  concerning the direction d 2 , and located at the central portion of the back portion  102  concerning the vertical direction. 
     The attachment portion  107  is disposed at a position different from the attachment portion  106 . In this embodiment, the attachment portion  107  is disposed in the side portion  104  on the toe side. For this reason, the attachment portions  106  and  107  are disposed at portions spaced apart from each other in the direction d 2 . The attachment portion  107  is located between the face portion  101  and the back portion  102  concerning the direction d 1 . For this reason, the attachment portions  106  and  107  are disposed at portions spaced apart from each other in the direction d 1  as well. 
     In the embodiment, the attachment portions  106  and  107  are threaded holes having the same diameter and same pitch. The attachment portion  106  is formed such that a center line d 13  crosses the face portion  101 . The attachment portion  107  is formed such that a center line d 14  is closer to the direction d 2  than the direction d 1 . In this embodiment, the center line d 14  is parallel to the direction d 2 . 
     The golf club head  100  includes interchangeable members  108  and  109 . In this embodiment, the interchangeable member  108  is a screw member integrally including a screw shaft  108   a  and a head portion  108   b . In this embodiment, the interchangeable member  109  is a screw member integrally including a screw shaft  109   a  and a head portion  109   b.    
     Each of the head portions  108   b  and  109   b  has a hole that has a closed bottom and engages with a tool such as a hexagonal wrench. Each of the screw shafts  108   a  and  109   a  has a shaft diameter and a screw thread pitch to threadably engage with the attachment portions  106  and  107 . Hence, the interchangeable member  108  can freely selectively be detached from either of the attachment portions  106  and  107 . Similarly, the interchangeable member  109  can freely selectively be detached from either of the attachment portions  106  and  107 . The attachment portions  106  and  107  open to the back portion  102  and the side portion  104 , respectively. This also makes it relatively easy to detach the interchangeable member  108  or  109 . 
     In this embodiment, the interchangeable members  108  and  109  have the same structure except the total length, and the total length of the interchangeable member  108  is longer, like the interchangeable members  18  and  19  according to the first embodiment. The interchangeable members  108  and  109  are solid metal members integrally made of metal materials having the same specific gravity. 
     In the golf club head  100  according to this embodiment, the attachment positions of the interchangeable members  108  and  109  can be selected. In the first attachment mode, the interchangeable member  108  is attached to the attachment portion  106 , and the interchangeable member  109  is attached to the attachment portion  107 . In the second attachment mode, the interchangeable member  108  is attached to the attachment portion  107 , and the interchangeable member  109  is attached to the attachment portion  106 . 
     The difference between the attachment modes will be described below with reference to  FIGS. 4B and 4C .  FIGS. 4B and 4C  are sectional views taken along a line II-II in  FIG. 4A .  FIG. 4B  is a sectional view in the first attachment mode.  FIG. 4C  is a sectional view in the second attachment mode. 
     As shown in  FIG. 4B , in the first attachment mode, the distal end of the interchangeable member  108  (the distal end of the screw shaft  108   a ) abuts against the rear surface of the face portion  101 . When the distal end of the screw shaft  108   a  abuts against the rear surface of the face portion  101 , deformation of the face portion  101  at an abutment portion P is restricted. That is, the interchangeable member  108  functions as a reinforcing member that locally restricts deformation of the face portion  101 . In this embodiment, the distal end of the screw shaft  108   a  is tapered and comes into point contact with the rear surface of the face portion  101 . This can suppress excessive restriction on deformation of the face portion  101 . The distal end of the screw shaft  108   a  may be in contact so as not to press the rear surface of the face portion  101  or so as to press the rear surface to the face side in the natural state. The degree of pressing may be adjustable by the degree of fastening of the screw shaft  108   a  in the attachment portion  106 . In the maximum fastening level, the distal end of the screw shaft  108   a  may slightly displace the rear surface of the face portion  101  to the face side. 
     In this embodiment, the abutment portion P is located at the central portion of the face portion  101  concerning the direction d 2  or on the lower side of the face portion  101  concerning the vertical direction. As for an example of the position of the abutment portion P, the abutment portion P may be located in a lower area R 3  described above with reference to  FIGS. 3A and 3B . 
     Referring to  FIG. 4C , in the second attachment mode, the distal end of the interchangeable member  109  does not abut against the rear surface of the face portion  101 . 
     A change in the characteristics of the golf club head  100  between the first attachment mode and the second attachment mode will be explained. In this embodiment, two types of characteristics simultaneously change between the two attachment modes. One of the characteristics is the rigidity distribution of the face portion  101 , and the remaining one is the position of center of gravity. 
     In the first attachment mode, deformation of the abutment portion P is restricted. As for the rigidity distribution of the face portion  101 , the rigidity is relatively low from the central portion to the upper portion and relatively high at the lower portion. In the iron type golf club head, generally, the impact point exists from the central portion to the lower portion of the face. That is, since the lower portion of the face portion  101  hardly flexes at impact, the hitting feel is good. Focusing on the center of gravity, the attachment portions  106  and  107  are spaced part from each other in the direction d 2 , and the interchangeable member  108  is heavier than the interchangeable member  109 . Hence, the position of center of gravity of the golf club head  100  is located relatively on the side of the hosel portion  105 . Hence, the golf club head  100  readily rotates about the shaft axis, and the operability improves. 
     In the second attachment mode, deformation of the face portion  101  is not restricted by the interchangeable members  108  and  109 . Hence, as for the rigidity distribution of the face portion  101 , the rigidity is not relatively high at the lower portion, unlike the first attachment mode. That is, the area having a high repulsion is wider than in the first attachment mode. Focusing on the center of gravity, the attachment portions  106  and  107  are spaced part from each other in the direction d 2 , and the interchangeable member  108  that is relatively heavy is located on the toe side. Hence, the moment of inertia of the golf club head  100  is larger than in the first attachment mode. For the above-described reasons, in the second attachment mode, the variation in the distance of a shot with respect to the variation in the impact point becomes relatively small. 
     As described above, in this embodiment, a golfer can change the rigidity distribution or the position of center of gravity of the face portion  101  by changing the combinations of the interchangeable members  108  and  109  and the attachment portions  106  and  107 . The rigidity distribution and the position of center of gravity are not changed irrelevantly. That is, in the first attachment mode, a rigidity distribution and a position of center of gravity which are suitable for the need of an advanced player, for example, a hitting feel and operability are obtained. In the second attachment mode, a rigidity distribution and a position of center of gravity which are suitable for a beginner, for example, suppressing a variation in the distance are obtained. Hence, the golfer can easily understand the difference in the characteristics of the golf club head  100  caused by the difference in the attachment position. 
     Other Embodiments 
     In the first embodiment, a screw structure is employed as a structure to freely detach the interchangeable members  18  and  19  from the attachment portions  16  and  17 . However, the present invention is not limited to this, and any other detachment structure may be employed. The structure and shape of the interchangeable members  18  and  19  are not limited to those described above. This also applies to the second embodiment. 
     In the first embodiment, the interchangeable members  18  and  19  have different weights. However, they may have the same weight. In this arrangement, however, the change in the center of gravity between the first attachment mode and the second attachment mode may be absent or very small, and only the rigidity distribution of the face portion  11  changes substantially. This also applies to the second embodiment. 
     In the first embodiment, the interchangeable members  18  and  19  are solid metal members. However, they may be hollow metal members. When hollow metal members are used, for example, the screw shafts  18   a  and  19   a  may have a cylindrical shape. This also applies to the second embodiment. 
     In the first embodiment, the interchangeable members  18  and  19  are metal members having the same specific gravity. However, they may be metal members having different specific gravities. In addition, the interchangeable members  18  and  19  may be made of materials other than metal materials. However, the interchangeable member  18  is preferably made of a material having a high rigidity because it restricts deformation of the face portion  11 . This also applies to the second embodiment. 
     In the first embodiment, the abutment portion P is located on the lower portion at the central portion of the face portion  11 . However, the present invention is not limited to this, and the position of the abutment portion P can be set in accordance with the range of a target sweet area. This also applies to the second embodiment. 
     In the first embodiment, the number of interchangeable members is two. However, the number of interchangeable members may be three or more. The number of attachment portions may also be three or more. In this case, each interchangeable member can freely be detached from any attachment portion. The positions of the attachment portions are not limited to those described above. This also applies to the second embodiment. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2014-122722, filed Jun. 13, 2014, which is hereby incorporated by reference herein in its entirety.