Patent Document

This is a continuation of application Ser. No. 10/851,673 filed May 24, 2004 now U.S. Pat. No. 7,048,646. The entire disclosure of the prior application, application Ser. No. 10/851,673, is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a putter head, and particularly to a putter head which is superior in absorbability of shock produced when hitting a ball. 
   2. Description of the Related Art 
   For the purpose of absorbing shock occurring when a putter head hits a ball and improving feeling of hitting, JP-A-2001-190721 discloses that a putter head includes a resin material such as urethane resin on a face surface thereof. 
   SUMMARY OF THE INVENTION 
   Since the resin material is exposed to the face surface in the putter head disclosed in JP-A-2001-190721, the resin material is damaged easily and has less durability. 
   The invention provides a putter head, which is superior in absorbability of shock occurring when hitting a ball and has good durability. 
   According to one embodiment of the invention, a putter head includes a first half body, a second half body, and an insert. The first half body includes a first metal, and has a face surface on a front face. The second half body includes a second metal, which is higher in specific gravity than the first metal, and is attached to the forward half body. The insert is disposed inside the first half body to be along the face surface and includes one selected from a group consisting of a synthetic resin and a rubber. 
   In the putter head, the insert, which disposed inside the first half body and includes one selected from the group consisting of the resin and the rubber, absorbs the shock occurring when hitting the ball. 
   Since, the insert is disposed along the face surface, the insert can absorb the shock easily. 
   The following configuration is preferable. The first half body defines a recess on a rear face thereof. The insert is disposed in the recess. The second half body presses the insert. With this configuration, since the insert is pressed against the first half body and closely contacted therewith, the shock produced in the first half body is securely transmitted to the insert, and sufficiently absorbed. 
   The following configuration may be adopted. The first half body extends in a toe-heel direction of the putter head. The second half body includes a first member and a second member. The first member continues from a toe side of the first half body to a heel side of the first half body and bulges toward rearward of the first half body. The second member protrudes from a center of the first half body in the toe-heel direction. One end of the second member continues to the first member. The first member and the second member are integrated with each other. A lid member is disposed at the other end of the second member and has a dimension so that the lid member is fitted to the recess. The first half body and the second half body are connected with each other so that the lid member presses the insert. With this configuration, the putter head has a large moment of inertia around the center of gravity, so that the sweet area of the putter head is wide. Also, the insert is sufficiently pressed against the first half body by the lid member. 
   In this case, the following configuration is preferable. The recess includes an entrance portion, an innermost portion, and a step portion. The entrance portion retreats from the rear face of the first half body. The innermost portion is formed behind the entrance portion and has smaller space than the entrance portion. The step surface is formed between the entrance portion and the innermost portion and is in parallel to the face surface. The insert is disposed in the innermost portion. The lid member is in contact with the step surface. Since the lid body is disposed in the innermost portion and contact with the step surface to press the insert, the insert is pressed and contracted at a predetermined ratio. Thereby, the shock absorption characteristic is securely achieved as designed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a putter head according to an embodiment of the invention. 
       FIG. 2  is a perspective view of the putter head of  FIG. 1 . 
       FIG. 3  is a bottom view of the putter head of  FIG. 1 . 
       FIG. 4  is a cross-sectional view taken along line IV-IV in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIGS. 1 to 4 , embodiments of the invention will be described below in detail.  FIG. 1  is an exploded perspective view of a putter head according to an embodiment of the present invention.  FIG. 2  is a perspective view of the putter head.  FIG. 3  is a bottom view of the putter head.  FIG. 4  is a cross-sectional view taken along line IV-IV in  FIG. 3 . 
   The putter head includes a forward half body  10  made of a low specific gravity metal material, a backward half body  20  made of a high specific gravity metal material, and an insert  30  made of rubber or a synthetic resin. The insert have hardness in a range of 20 (JISC) to 90 (JISC), preferably in a range of 30 (JISC) to 80 (JISC). 
   The forward half body  10  has a shape of almost rectangular parallelepiped extending in a toe-heel direction connecting a toe (left end in  FIG. 2 ) and a heel (right end in  FIG. 2 ). A sole face  10   s  of the forward half body  10  has a circular arc shape in which a central part in the toe-heel direction slightly bulges toward the lower side. A front face of the front half body  10  is a face surface  10   a  for hitting a ball. 
   On the back face of the forward half body  10 , a recess  11  is formed in the neighbor of a middle part in the toe-heel direction. This recess  11  includes an entrance portion  11   a , an innermost portion  11   b , and a step surface  11   c . The innermost portion  11   b  is concave from the innermost side of the entrance portion  11   a  (the side of the face surface  10   a ) toward the face surface  10   a . The step surface  11   c  is formed in a boundary between the entrance portion  11   a  and the innermost portion  11   b . The entrance portion  11   a  is a notch extending in the toe-heel direction and opening to the back face and the bottom face of the forward half body  10 . The innermost portion  11   b  is a groove being concave from the face surface  10   a  side of the entrance portion  11   a . The inner most portion  11   b  extends in the toe-heel direction. The innermost portion  11   b  is slightly smaller than the entrance portion  11   a . The step surface  11   c  resides all around the innermost portion  11   b.    
   Notch portions  12  are formed on both ends of the forward half body  10  in the toe-heel direction on the back surface thereof. The notch portions open to the sole face  10   s . Insertion holes  13  for bolts  14  are formed to communicate the face surface  10   a  side of the notch portion  12  with the face surface  10   a . Each insertion hole  13  has a large diameter portion on the face surface  10   a  side and a small diameter portion on the back face side, as with an insertion hole  23   a  described later. A head portion of the bolt  14  is disposed in the large diameter portion of the insertion hole  13 . 
   A shaft insertion hole  15  is formed in an upper face of the forward half body  10  on the heel side. 
   The backward half body  20  includes an outer circumferential bar-like body  21  having a semi-circular arc shape, a central bar-like body  22  integrated with a central part of the outer circumferential bar-like body  21  in an extending direction, and a lid body  23  attached to a top end face of the central bar-like body  22  by a bolt  24 . A rear bottom face of the central bar-like body  22  constitutes a slant face  20   a  ( FIG. 4 ) with a gradient rising toward the aftermost end of the backward half body  20 . 
   Both end portions of the outer circumferential bar-like body  21  have a shape and dimension so that the both ends can be fitted into the notch portions  12 . Female screw holes (not shown) coaxial with the insertion hole  13  are formed on surfaces of the both ends of the outer circumferential bar-like body  21 , respectively. The both ends of the outer circumferential bar-like body  21  is fitted to the notch portions  12  and the bolts  14  are screwed into the screw holes, thereby the forward half body  10  and the backward half body  20  are connected. 
   The lid body  23  has dimension so that the lid body  23  can be fitted to the entrance portion  11   a  As shown in  FIG. 4 , the lid body  23  is fixed to the central bar-like body  22  by screwing a bolt  24  into the female screw hole  22   a  provided at the top end face of the central bar-like body  22  through the insertion hole  23   a  provided in the lid body  23 . 
   The insert  30  has longitudinal and transverse dimensions almost equivalent to the innermost portion  11   b , and has a thickness (dimension in forward and backward direction of the head) slightly larger than the depth of the innermost portion  11   b  (e.g., by about 0.5 mm to 2 mm). 
   In assembling the putter head, after the insert  30  is inserted into the innermost portion  11   b , the backward half body  20  with the lid body  23  is assembled with the forward half body  10 , and then the bolts  14  are screwed. Thereby, both end faces  21   a  of the outer circumferential bar-like body  21  are contacted with the innermost faces of the notch portions  12 , and the lid body  23  is contacted with the step surface  11   c  while pressing the insert  30 . The insert  30  is closely contacted with all the inner periphery of the innermost portion  11   b  and the entire face of the lid body  23 . 
   When a shaft is attached to the putter head  1 , a putter is finished. 
   Since the insert  30  absorbs shock occurring when the putter hits a ball, the feeling of hitting is softened. The insert  30  is closely contacted with the forward half body  10  and the lid body  23  without gap. Also, a distance between the insert  30  and the face surface  10  is short (preferably, in a range of from 1 mm to 5 mm, more preferably, from 2 mm to 4 mm). Therefore, the shock is sufficiently absorbed. 
   In this embodiment, since the backward half body  20  having high specific gravity is formed in a circular arc, the sweet area of the putter head is wide, and less shock occurs when a golfer hits a ball out of the sweet spot. 
   Preferably, the forward half body  10  is made of aluminum, magnesium, titanium, or their alloy, with the specific gravity of from 2 to 5. It should be noted that the invention is not limited thereto. 
   Preferably, the backward half body  20  is made of stainless, copper alloy, tungsten alloy (e.g., W—Cu alloy, W—Ni alloy), with the specific gravity of 7 to 14.

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