Method of adjusting coefficient of restitution of face of golf club head

Abstract

The present invention provides a method of adjusting a coefficient of restitution (COR) of the face of a golf club head. A metallic assistant device is fixed on a center of a back of the face by friction welding or brazing. The metallic assistant may increases the central thickness of the face that may reduce the COR of the face.

1 . A method of adjusting a coefficient of restitution of the face of a golf club head comprising the step of fixing an assistant device, which is made of metal, on a back of the face to reduce the coefficient of restitution of the face. 
   
   
       2 . The method as defined in  claim 1 , wherein the assistant device is fixed on the face by friction welding. 
   
   
       3 . The method as defined in  claim 2 , further comprising the step of performing brazing to fix the assistant device and the face after the friction welding. 
   
   
       4 . The method as defined in  claim 1 , wherein the assistant device is fixed on the face by brazing. 
   
   
       5 . The method as defined in  claim 4 , further comprising the step of performing spot welding to pre-fix the assistant device and the face prior to the brazing. 
   
   
       6 . The method as defined in  claim 1 , wherein the assistant device and the face are made of the same material. 
   
   
       7 . The method as defined in  claim 1 , wherein the assistant device and the face are made of different materials. 
   
   
       8 . The method as defined in  claim 1 , wherein the assistant device is a substantially round member. 
   
   
       9 . The method as defined in  claim 1 , wherein the assistant device is a substantially annular member. 
   
   
       10 . The method as defined in  claim 1 , wherein the assistant device has a recess. 
   
   
       11 . A method of adjusting a coefficient of restitution of the face of a golf club head comprising the step of fixing an assistant device, which is made of metal, on a back of the face by friction welding, wherein the assistant device and the face are made of the same material. 
   
   
       12 . The method as defined in  claim 11 , wherein the assistant device is a substantially round member. 
   
   
       13 . The method as defined in  claim 11 , wherein the assistant device has a through hole. 
   
   
       14 . The method as defined in  claim 11 , wherein the assistant device has a recess. 
   
   
       15 . A method of adjusting a coefficient of restitution of the face of a golf club head comprising the step of fixing an assistant device, which is made of metal, on a back of the face by brazing, wherein the assistant device and the face are made of different materials.