IP Library Granted Patent US 8,900,068
Granted Patent B2
US 8,900,068 · App. 13/644,851 · Granted Dec 2, 2014

Golf club shaft

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Quick Facts
Patent No.
US 8,900,068
App. No.
13/644,851
Granted
Dec 2, 2014
Kind
B2
Abstract

A golf club shaft, wherein when a distance from a shaft front end to a shaft gravity center point is L G and full length of the shaft is L S , 0.54≦L G /L S ≦0.65 is satisfied, a shaft weight is 55 g or less, and a bending rigidity value EI at a point of 630 mm from the shaft front end to the shaft rear end side is 2.3 kgf·m 2 or less.

Claims (3)

1. A golf club shaft, wherein said shaft has a weight of 55 grams or less, and when a distance from a tip end of the shaft to a shaft gravity center point is LG and full length of the shaft is Ls, the relationship 0.54≦Lg/Ls≦0.65 is satisfied, and wherein a bending rigidity value EI at a point of 630 mm from the shaft tip end to the shaft butt end side is 2.3 kgf*m2 or less, and wherein a weight ratio of a butt partial layer includes a butt partial layer with respect to the shaft weight is not smaller than 5 weight-% and not larger than 50 weight-%, wherein the butt partial layer includes a butt straight layer, butt hoop layer, and butt bias layer.

2. The golf club shaft according to claim 1 , wherein a low elasticity material including fibers with a fiber elastic modulus of 20 t/mm 2 or less is used for a butt side part.

3. The golf club shaft according to claim 2 , wherein a fiber orientation angle of the fibers in the low elasticity material is 0±10 degrees.

Assignments (2)
MERGER Recorded Apr 17, 2018
From: DUNLOP SPORTS CO. LTD.
To: SUMITOMO RUBBER INDUSTRIES, LTD.
Reel/Frame 045959/0204 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Oct 11, 2012
From: HASEGAWA, HIROSHI; NAKANO, TAKASHI
To: DUNLOP SPORTS CO. LTD.
Reel/Frame 029111/0427 →