Intermediate layer for joining two portions of a golf club head

Abstract

A golf club head includes a first portion forming a part of the head body of the golf club head, a second portion forming another part of the head body of the golf club head, and an intermediate layer. The first portion, the second portion, and the intermediate layer are made of different materials. Each of the first portion and the second portion has an abutting portion, with the intermediate layer being positioned between the abutting portion of the first portion and the abutting portion of the second portion. The intermediate layer and the abutting portion of the first portion are joined together by friction welding, and the intermediate layer and the abutting portion of the second portion are joined together by friction welding, thereby forming a golf club head product.

1 . A golf club head comprising: 
 a first portion forming a part of a head body of the golf club head, the first portion being made of a first metal material and including an abutting portion;    a second portion forming another part of the head body of the golf club head, the second portion being made of a second metal material and including an abutting portion, one of said first portion and said second portion including an annular wall for receiving and positioning the intermediate thin layer before friction welding; and    an intermediate thin layer made of a third metal material, the intermediate thin layer being positioned between the abutting portion of the first portion and the abutting portion of the second portion, the intermediate thin layer and the abutting portion of the first portion being joined together by friction welding, the intermediate thin layer and the abutting portion of the second portion being joined together by friction welding.    
   
   
       2 . The golf club head as claimed in  claim 1 , wherein the abutting portion of the first portion is formed on an extension extending from a heel of the head body, and wherein the abutting portion of the second portion is formed on a hosel.  
   
   
       3 . The golf club head as claimed in  claim 1 , wherein the first metal material, the second metal material, and the third metal material are different from one another, a metallurgical compatibility between the first metal material and the third metal material being better than that between the first metal material and the second metal material, a metallurgical compatibility between the second metal material and the third metal material being better than that between the first metal material and the second metal material.  
   
   
       4 . The golf club head as claimed in  claim 3 , wherein the first metal material is selected from the group consisting of stainless steel, titanium alloy, carbon steel, low-alloy steel, cast iron, nickel-base alloy, structural steel, Fe—Mn—Al alloy, and super alloy.  
   
   
       5 . The golf club head as claimed in  claim 3 , wherein the second metal material is selected from the group consisting of stainless steel, titanium alloy, carbon steel, low-alloy steel, cast iron, nickel-base alloy, structural steel, Fe—Mn—Al alloy, and super alloy.  
   
   
       6 . The golf club head as claimed in  claim 3 , wherein the third metal material is selected from the group consisting of niobium, chromium, aluminum, iron, zirconium, titanium, vanadium, tantalum, silver, nickel, tungsten, and alloys thereof.  
   
   
       7 . The golf club head as claimed in  claim 2 , wherein the abutting portion of the extension includes the annular wall for receiving the intermediate thin layer before friction welding.  
   
   
       8 . The golf club head as claimed in  claim 2 , wherein the abutting portion of the hosel includes the annular wall for receiving the intermediate thin layer before friction welding.  
   
   
       9 . The golf club head as claimed in  claim 1 , wherein the intermediate thin layer is tablet-like, powdery, or pasty.  
   
   
       10 . The golf club head as claimed in  claim 1 , wherein the intermediate thin layer is provided on at least one of the abutting portion of the first portion and the abutting portion of the second portion by one of electroplating and spraying before friction welding.  
   
   
       11 . The golf club head as claimed in  claim 1 , wherein each of the abutting portions includes a surface roughness smaller than Ra 25 μm.  
   
   
       12 . The golf club head as claimed in  claim 2 , wherein the intermediate thin layer has a generally circular disc shape.  
   
   
       13 . The golf club head as claimed in  claim 1 , wherein the intermediate thin layer has a generally circular disc shape.  
   
   
       14 . The golf club head as claimed in  claim 13 , wherein the golf club has a shaft with a longitudinal axis and wherein the intermediate layer is intersected by the longitudinal axis of the shaft.  
   
   
       15 . The golf club head as claimed in  claim 1 , wherein the golf club has a shaft with a longitudinal axis and wherein the intermediate layer is intersected by the longitudinal axis of the shaft.  
   
   
       16 . The golf club head as claimed in  claim 1 , wherein said annular portion of the first portion or the second portion is removed after friction welding.