Hydroformed metallic golf club shafts and method therefore

Abstract

Method for preparing a golf club shaft, set of shafts, or golf clubs having shafts which have been produced by a process that includes a hydroforming step. By utilizing a hydroforming process step, a metal or metal matrix composite golf club shaft can be formed into a variety of configurations or shapes heretofore not possible and can include hydroformed ornamental design features.

1 . A method for forming a hydroformed golf club shaft comprising the steps of: 
 drawing a tube over at least one mandrel to reduce an outer diameter of said tube;    optionally, varying the wall thickness in at least one portion of said tube during the drawing step;    step forming said tube into a shaft blank by introducing at least one step into said shaft, said shaft blank comprising a grip section, a tip section and an intermediate section,    placing said shaft blank in a hydroforming apparatus having a mold cavity;    expanding one or more said sections of said shaft blank through hydroforming so that an outer diameter of said shaft substantially conforms to inner diameter dimensions of the hydroform mold cavity; and    cutting said hydroformed shaft to a desired length.    
   
   
       2 - 17 . (canceled)  
   
   
       18 . A method for forming a hydroformed golf club shaft, comprising the steps of: 
 forming a golf club shaft having a tip section, a grip section, and an intermediate section interconnecting said grip and tip sections,    placing the shaft into a mold of a hydroforming apparatus,    fluid expanding at least a portion of one section of said shaft in said mold to substantially conform said shaft to interior dimensions of the mold; and    removing said shaft from said hydroforming apparatus.    
   
   
       19 . A method according to  claim 18 , wherein said tip section has a smaller outer diameter than said grip section, and wherein said forming step includes (a) a drawing process, or (b) a step forming process, or a combination of (a) and (b).  
   
   
       20 . A method according to  claim 19 , wherein said fluid expansion step is performed at a pressure of about 10,000 to about 50,000 psi.  
   
   
       21 . A method according to  claim 18 , wherein a design element is formed on said shaft during said fluid expanding step.  
   
   
       22 . A method according to  claim 21 , wherein said design element comprises a protrusion, an indentation, a groove, a ridge, a ring, a line, a geometric pattern, an arbitrary pattern, a logo, or a symbol.  
   
   
       23 . A method according to  claim 18 , wherein at least one of said shaft sections has an outer diameter which is at least 50% of a corresponding inner diameter of said hydroform mold.  
   
   
       24 . A method according to  claim 18 , wherein at least one of said shaft sections has an outer diameter which is at least 90% of a corresponding inner diameter of said hydroform mold.  
   
   
       25 . A method according to  claim 18 , wherein said tapered section has a substantially constant taper, or wherein said tapered section has at least two steps.  
   
   
       26 . A method according to  claim 25 , wherein a design element is formed on said shaft during said fluid expanding step.  
   
   
       27 . A method according to  claim 26 , wherein said design element comprises a protrusion, an indentation, a groove, a ridge, a ring, a line, a geometric pattern, an arbitrary pattern, a logo or a symbol.  
   
   
       28 . A method according to  claim 18 , wherein said shaft includes metallurgically formed rifling on an interior surface of the shaft.  
   
   
       29 . A method according to  claim 26 , wherein said shaft includes metallurgically formed rifling on an interior surface of the shaft.  
   
   
       30 . A method according to  claim 28 , wherein said rifling comprises a plurality of longitudinally extending lands and grooves.  
   
   
       31 . A method according to  claim 29 , wherein said rifling comprises a plurality of longitudinally extending lands and grooves.  
   
   
       32 . A method according to  claim 18 , wherein after said shaft is fluid expanded, at least one of the following steps is performed: heat treating said shaft, polishing said shaft, or plating said shaft, and wherein said forming step includes (a) a drawing process, or (b) a step forming process, or a combination of (a) and (b).  
   
   
       33 . A method according to  claim 23 , wherein after said shaft is fluid expanded, at least one of the following steps is performed: heat treating said shaft, polishing said shaft, or plating said shaft, and wherein said forming step includes (a) a drawing process, or (b) a step forming process, or a combination of (a) and (b).  
   
   
       34 . A method according to  claim 32 , wherein said fluid expansion step is performed at a pressure of about 10,000 to about 50,000 psi.  
   
   
       35 . A method according to  claim 32 , wherein said shaft prior to fluid expanding has an outer diameter section which is at least 80% of a corresponding inner diameter dimension of said hydroform mold cavity, and wherein said shaft intermediate section after fluid expanding has one or more step sections or a substantially constant taper.  
   
   
       36 . A method according to  claim 33 , wherein said shaft prior to fluid expanding has an outer diameter section which is at least 80% of a corresponding inner diameter dimension of said hydroform mold cavity and wherein said shaft intermediate section after fluid expanding has one or more step sections or a substantially constant taper.