Golf club head

Abstract

A golf club head has a hollow structure comprising a face member and a main member. The face member is made of a first titanium alloy having a specific gravity G 1 of less than 4.42. The main member is made of a second titanium alloy having a specific gravity G 2 of less than 4.42, the first titanium alloy and second titanium alloy have different compositions.

1 . A golf club head having a hollow structure comprising
 a face member made of a first titanium alloy having a specific gravity G 1  of less than 4.42, and   a main member made of a second titanium alloy having a specific gravity G 2  of less than 4.42 and being different in the composition from the first titanium alloy.   
   
   
       2 . The golf club head according to  claim 1 , wherein
 the elastic modulus E 1  of the first titanium alloy is more than   the elastic modulus E 2  of the second titanium alloy.   
   
   
       3 . The golf club head according to  claim 1 , wherein
 the face member is formed by forging or alternatively press molding, and   the main member is formed by casting.   
   
   
       4 . The golf club head according to  claim 1 , wherein
 the specific gravity of the first titanium alloy is less than 4.40, and   the specific gravity of the second titanium alloy is less than 4.40.   
   
   
       5 . The golf club head according to  claim 1 , wherein
 the quotient (E 1 /G 1 ) of the elastic modulus E 1  of the first titanium alloy divided by the specific gravity G 1  thereof is in a range of from 27.0 to 32.0, and   the quotient (E 2 /G 2 ) of the elastic modulus E 2  of the second titanium alloy divided by the specific gravity G 2  thereof is not less than 23.0 and less than 27.0.   
   
   
       6 . The golf club head according to  claim 1 , wherein
 the ratio (G 1 /G 2 ) of the specific gravity G 1  of the first titanium alloy to the specific gravity G 2  of the second titanium alloy is in a range of from 0.98 to 1.02.   
   
   
       7 . The golf club head according to  claim 1 , wherein
 the elastic modulus E 1  of the first titanium alloy is not less than 110 GPa and not more than 140 GPa.   
   
   
       8 . The golf club head according to  claim 1 , wherein
 the elastic modulus E 2  of the second titanium alloy not less than 95 GPa and not more than 120 GPa.   
   
   
       9 . The golf club head according to  claim 1 , wherein
 the quotient (E 2 /G 2 ) of the elastic modulus E 2  of the second titanium alloy divided by the specific gravity G 2  thereof is not less than 23.0 and not more than 27.5.   
   
   
       10 . The golf club head according to  claim 1 , wherein
 the face member comprises a face plate whose front surface defines the club face, and a turnback extending backwards from the edge of the face plate, and   the weight W 1  of the face member is not more than 75 grams and not less than 40 grams.   
   
   
       11 . The golf club head according to  claim 10 , wherein
 the face member comprises a face plate whose front surface defines the club face, and a turnback extending backwards from the edge of the face plate,   the weight W 1  of the face member is not more than 75 grams and not less than 40 grams, and   the weight W 2  of the main member is not less than 110 grams and not more than 155 grams.   
   
   
       12 . The golf club head according to  claim 1 , which further includes
 a separate weight member fixed to the main member and having a weight W 3  of not less than 3 grams and not more than 20 grams.   
   
   
       13 . The golf club head according to  claim 1 , wherein
 the face member is composed of a face plate whose front surface defines the club face and not provided with a turnback, and   the weight W 1  of the face member is in a range of from 35 to 60 grams.