Hollow golf club with composite core

Abstract

A golf club having a hollow club head construction with a lightweight composite core inserted into the club head cavity and juxtaposed against a front face by compressed gas to provide support to the front face therein. The core material is less dense and having greater flexibility than the front face. The front face has a variable stiffness so as to create a variable Coefficient of Restitution (COR) across the face, therein normalizing the hitting area over a greater portion of the face. The composite core in cooperation with the front face to provide a COR from about 0.8 in the middle of the face to about 0.9 in the outer section. The body of the club head having at least one opening wherein the composite core is visible and provides the shell for that portion of the club head.

What is claimed is:  
     
         1 . A golf club head comprising: 
 a body made of a first material having a front face of variable stiffness, and a rear cavity extending rearward from the front face;    a composite core comprised of a second material less dense and more flexible than the first inserted into the rear cavity; and    the composite core inflated and expanded by a pressurized gas wherein at least a portion of the composite core biasly juxtaposes against the front face to form a hollow body having an internal volume between 35 cc to 50 cc.    
     
     
         2 . The club head of  claim 1 , wherein the composite core is made from a lightweight material such as plastic or carbon graphite.  
     
     
         3 . The club head of  claim 2 , wherein the composite core material has a density equal or less than 4.5 gm/cc.  
     
     
         4 . The club head of  claim 1 , wherein the stiffness of the front face is greatest at the face center, and becomes progressively more flexible away from the face center.  
     
     
         5 . The club head of  claim 1 , wherein the Coefficient of Restitution varies across the front face to normalize ball speed and provide for an enlarged sweet zone.  
     
     
         6 . The club head of  claim 5 , wherein the maximum Coefficient of Restitution, ranges between about 0.8 to about 0.9.  
     
     
         7 . The club head of  claim 1 , wherein the pressurized gas is air.  
     
     
         8 . The club head of  claim 1 , wherein the rear cavity comprises an opening that is sealed by a visible portion of the composite core.  
     
     
         9 . The club head of  claim 1 , wherein the elasticity of the material of the composite core may cooperate with the front face to create a varying COR across the front face for normalizing ball speed and creating an enlarged sweet zone.  
     
     
         10 - 22 . (Cancelled)