Golf club and manufacturing method thereof

Abstract

A gold club in which the repulsion area of the face portion is shifted downward, and a manufacturing method of such a golf club are provided. The structure of the golf club is such that, in order to shift the sweet area of a face portion having a striking face downward, a crown portion is subjected to an age hardening process to intentionally enhance any one or more of the mechanical qualities of material of the rigidity, strength and hardness of the crown portion. By shifting the sweet area downward, eventually a repulsion effect in the shifted position can be improved, and a ball can be struck without causing a decrease in a traveling distance as in the case when striking the ball on the upper position, even if the striking position is the position shifted to the lower part of the face portion.

1 . A golf club, comprising: 
 a face portion which is disposed at a front face of a metallic hollow golf clubhead and has a striking surface for striking a golf ball; and    a body portion which constitutes a remaining part of the clubhead other than the face portion,    wherein the body portion has a sole portion which forms a lower portion of the metallic hollow golf clubhead, and a crown portion which forms an upper portion of the metallic hollow golf clubhead, the crown portion having a structure in which any one or more mechanical qualities of material of rigidity, strength and hardness is intentionally enhanced with respect to the sole portion.    
   
   
       2 . The golf club according to  claim 1 , wherein the metals are plates, and the rigidity, strength and hardness of the crown portion are made different by subjecting the plates to a heat treatment.  
   
   
       3 . The golf club according to  claim 1 , wherein the metals are plates, and the rigidity, strength and hardness are made different by making the materials of the plates different.  
   
   
       4 . The golf club according to any of  claims 1  to  3 , wherein the body portion is obtained by weldbonding the sole portion, the crown portion, and the hosel portion to which the shaft is connected.  
   
   
       5 . A method for manufacturing a golf club which comprises a face portion which is disposed at a front face of a metallic hollow golf clubhead and has a striking surface for striking a golf ball, and a body portion which constitutes a remaining part of the clubhead other than the face portion, the method comprising the steps of: 
 intentionally changing, so as to enhance, any one or more mechanical qualities of material of rigidity, strength and hardness of a metal constituting a crown portion, which forms an upper portion of the metallic hollow golf club and is a part of the body portion, with respect to a sole portion which forms a lower portion of the metallic hollow golf club and is a part of the body portion; and    adjusting the position of a sweet area on the striking surface.    
   
   
       6 . The method for manufacturing a golf club according to  claim 5 , wherein the metals are plates, and the rigidity, strength and hardness of the crown portion are made different by subjecting the plates to a heat treatment.  
   
   
       7 . The method for manufacturing a golf club according to  claim 5 , wherein the metals are plates, and by differing the materials of the metals constituting the sole portion and the crown portion, the rigidity, strength and hardness of the metals are made different.  
   
   
       8 . The method for manufacturing a golf club according to any of  claims 5  to  7 , wherein the body portion is obtained by weldbonding the sole portion, the crown portion, and the hosel portion to which the shaft is connected.  
   
   
       9 . The method for manufacturing a golf club according to  claim 8 , wherein the weldbonding is performed by hardening only the crown portion by means of a heat treatment, followed by welding the face portion and each portion of the body portion.  
   
   
       10 . The method for manufacturing a golf club according to  claim 9 , wherein the metal for the crown portion is a metal plate obtained by age hardening a β titanium alloy, and the metal for the sole portion is another metal plate obtained without age hardening the same.