Golf club head and golf club

Abstract

The inner surface of the hollow portion of the golf club head according to the present invention includes either or both of a concave surface and a flat surface. On the other hand, the projecting portion provided on the inner surface of the hollow portion, if any, is so formed that it has a convex surface with a radius of curvature equal to or greater than 3 mm, or chamfered at a level of C3 or more (JIS B0701-1987 standard). Owing to such structure, the golf club head can be manufactured with good efficiency even if the molding is performed using a bladder because the rate of molding failure upon such molding is reduced while the characteristics of the golf club head are ensured. The golf club of the present invention has such a golf club head as above.

1 . A method for manufacturing a golf club head which comprises outer shell members and a hollow portion surrounded by the outer shell members, comprising the steps of: 
 integrating first outer shell members to form a face portion, a side portion and a sole portion, in which a projecting portion is provided on an inner surface of the hollow portion; and    setting a second outer shell member on the integrated first outer shell members to form the hollow portion and bonding the second outer shell member to the integrated first outer shell members by applying pressure from inside to outside of the the hollow portion on inner surfaces of the first integrated outer shell members and the second outer shell member, thereby forming a crown portion of the golf club head,    wherein the projecting portion is formed so as to have a convex surface with a radius of curvature equal to or greater than 3 mm, or the projecting portion is chamfered by chipping off a corner edge of an angular portion, where two surfaces of the projecting portion intersect at an angle, by 3 mm or more along the two surfaces, before the second outer shell member is bonded to the first integrated outer shell members.    
   
   
       2 . The method according to  claim 1 , wherein the convex surface is formed by using a sheet member comprising a resin on a surface of the projecting portion.  
   
   
       3 . The method according to  claim 2 , wherein the sheet member comprises a fiber reinforced resin material.  
   
   
       4 . (canceled)  
   
   
       5 . The method according to  claim 1 , wherein a columnar neck member having a shaft insertion hole into which a golf club shaft is inserted, is provided to the first outer shell members, the hole being closed at one end, wherein the neck member projects into the hollow portion and its end on a projection side is so formed that the end has a convex surface with a radius of curvature equal to or greater than 3 mm, or chamfered by chipping off a corner edge of an angular portion, where two surfaces of the end on the projection side intersect at an angle, by 3 mm or more along the two surfaces.  
   
   
       6 . The method according to  claim 5 , wherein a lateral surface of the columnar neck member on a heel side is joined to the first outer shell members and the lateral surface on the heel side is covered with a joining surface of the first outer shell members so that a concave space may not be formed between the lateral surface on the heel side and the first outer shell members within the hollow portion.  
   
   
       7 . A golf club head comprising an outer shell member and a hollow portion surrounded by the outer shell member, wherein: 
 an inner surface of the hollow portion includes either or both of a concave surface and a flat surface and the inner surface has no projecting portion formed thereon.    
   
   
       8 . A golf club which has a grip, a golf club shaft, and a golf club head, wherein: 
 the golf club head comprises an outer shell member and a hollow portion surrounded by the outer shell member; an inner surface of the hollow portion includes either or both of a concave surface and a flat surface and a projecting portion is formed on the inner surface; and the projecting portion is so formed that it has a convex surface with a radius of curvature equal to or greater than 3 mm, or chamfered by chipping off a corner edge of an angular portion, where two surfaces of the projecting portion intersect at an angle, by 3 mm or more along the two surfaces.    
   
   
       9 . A golf club which has a grip, a golf club shaft, and a golf club head, wherein: 
 the golf club head comprises an outer shell member and a hollow portion surrounded by the outer shell member; and an inner surface of the hollow portion includes either or both of a concave surface and a flat surface and the inner surface has no projecting portion formed thereon.