Golf club shaft

Abstract

A golf club shaft ( 10 ) having a plurality of flexural-rigidity-reduced regions (R 1 through R 3 ) each disposed adjacently to a side rearward from a corresponding local maximum-value point (P 1 through P 3 ) in flexural rigidity in a full length of the golf club shaft ( 10 ) from a tip ( 11 ) thereof where a head is mounted to a butt ( 12 ) thereof where a grip is mounted. Each of the flexural-rigidity-reduced regions (R 1 through R 3 ) has a flexural rigidity value lower than a flexural rigidity value (maximum value) (Yp 1 through Yp 3 ) of the corresponding local maximum-value point (P 1 through P 3 ) in flexural rigidity. Thereby the golf club shaft ( 10 ) is entirely flexible.

1 . A golf club shaft having: 
 a plurality of flexural-rigidity-reduced regions in an axial direction from a tip side of said golf shaft toward a butt side thereof,    a local maximum-value point of the flexural-rigidity value is formed in each region interposed between two of said adjacent flexural-rigidity-reduced regions, so that a plurality of said local maximum-value points are disposed in the axial direction from a tip side of said golf shaft toward a butt side thereof.    
     
     
         2 . The golf club shaft according to  claim 1 , wherein said flexural rigidity values of said local maximum-value points are equal to each other or increase in a direction from said tip side toward said butt side; and flexural rigidity values of local minimum-points of said flexural-rigidity-reduced regions are equal to each other or increase in said direction from said tip side toward said butt side.  
     
     
         3 . The golf club shaft according to  claim 1 , wherein a length of each of said flexural-rigidity-reduced regions in said axial direction of said golf club shaft is set to a range not less than 50 mm nor more than 400 mm.  
     
     
         4 . The golf club shaft according to  claim 2 , wherein a length of each of said flexural-rigidity-reduced regions in said axial direction of said golf club shaft is set to a range not less than 50 mm nor more than 400 mm.  
     
     
         5 . The golf club shaft according to  claim 1 , wherein at least one of said flexural-rigidity-reduced regions is formed in a region from said tip to a position spaced by 500 mm from said tip.  
     
     
         6 . The golf club shaft according to  claim 2 , wherein at least one of said flexural-rigidity-reduced regions is formed in a region from said tip to a position spaced by 500 mm from said tip.  
     
     
         7 . The golf club shaft according to  claim 3 , wherein at least one of said flexural-rigidity-reduced regions is formed in a region from said tip to a position spaced by 500 mm from said tip.  
     
     
         8 . The golf club shaft according to  claim 1 , wherein a flexural rigidity value of said local maximum-value point at a tip side is set to a range of not less than 1.2 times nor more than 2 times as large as a flexural rigidity value of a local minimum-value point of said flexural-rigidity-reduced region adjacent to said local maximum-value point.  
     
     
         9 . The golf club shaft according to  claim 2 , wherein a flexural rigidity value of said local maximum-value point at a tip side is set to a range of not less than 1.2 times nor more than 2 times as large as a flexural rigidity value of a local minimum-value point of said flexural-rigidity-reduced region adjacent to said local maximum-value point.  
     
     
         10 . The golf club shaft according to  claim 3 , wherein a flexural rigidity value of said local maximum-value point at a tip side is set to a range of not less than 1.2 times nor more than 2 times as large as a flexural rigidity value of a local minimum-value point of said flexural-rigidity-reduced region adjacent to said local maximum-value point.  
     
     
         11 . The golf club shaft according to  claim 5 , wherein a flexural rigidity value of said local maximum-value point at a tip side is set to a range of not less than 1.2 times nor more than 2 times as large as a flexural rigidity value of a local minimum-value point of said flexural-rigidity-reduced region adjacent to said local maximum-value point.  
     
     
         12 . The golf club shaft according to  claim 1 , comprising a laminate of a plurality of prepregs each constructing a bias layer and a plurality of prepregs each constructing a straight layer, 
 wherein at least one layer of said straight layers serves as a flexural rigidity-adjusting layer having a plurality of separate prepregs, having an equal thickness and different elastic moduli, which are arranged in an axial direction of said golf club shaft to form said flexural rigidity distribution.    
     
     
         13 . The golf club shaft according to  claim 2 , comprising a laminate of a plurality of prepregs each constructing a bias layer and a plurality of prepregs each constructing a straight layer, 
 wherein at least one layer of said straight layers serves as a flexural rigidity-adjusting layer having a plurality of separate prepregs, having an equal thickness and different elastic moduli, which are arranged in an axial direction of said golf club shaft to form said flexural rigidity distribution.    
     
     
         14 . The golf club shaft according to  claim 3 , comprising a laminate of a plurality of prepregs each constructing a bias layer and a plurality of prepregs each constructing a straight layer, 
 wherein at least one layer of said straight layers serves as a flexural rigidity-adjusting layer having a plurality of separate prepregs, having an equal thickness and different elastic moduli, which are arranged in an axial direction of said golf club shaft to form said flexural rigidity distribution.    
     
     
         15 . The golf club shaft according to  claim 5 , comprising a laminate of a plurality of prepregs each constructing a bias layer and a plurality of prepregs each constructing a straight layer, 
 wherein at least one layer of said straight layers serves as a flexural rigidity-adjusting layer having a plurality of separate prepregs, having an equal thickness and different elastic moduli, which are arranged in an axial direction of said golf club shaft to form said flexural rigidity distribution.