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US 8,998,745 B2Granted
Golf club shaft
AssigneeDunlop Sports Co. Ltd.
InventorsHiroshi Hasegawa, Takashi Nakano
Life of this patent
Estimating the term…
Abstract
When a distance from a shaft front end to a shaft gravity center point is LG and a full length of the shaft is LS, 0.54≦LG/LS≦0.65 is satisfied. A golf club shaft, wherein a shaft weight is 56 g or more, and a bending rigidity value EI at a point of 630 mm from the shaft front end to the shaft rear end side is 3.6 kgf·m2 or less.
Claims19
A golf club shaft having:
- a front tip end and a rear butt end, wherein the rear butt end is formed from a low elasticity material including fibers with a fiber elastic modulus of 20 t/mm2 or less,
- a shaft weight in the range 56 grams to 80 grams, and
- a bending rigidity value EI at a point 630 mm from the shaft front end to the shaft rear end of 3.6 kgf·m2 or less and a bending rigidity value EI at a point 730 mm from the shaft front end to the shaft rear end side is in the range 2.7 kgf·m2 to 4.6 kgf·m2,
- wherein if the distance from the shaft front end to the shaft gravity center point is LG and the full length of the shaft is LS, then 0.54≦LG/LS≦0.65 is satisfied and
- wherein
- the shaft comprises a tubular body formed from multiple fiber reinforced resin layers of full axial length and at least one butt partial layer of partial axial length extending from the rear butt end, P2 is a point separated from the butt end by 250 millimeters, a range from point P2 to the butt end is defined as a specific butt range, Wa is the weight of the butt partial layer in the specific butt range, and Wb is the weight of the shaft in the specific butt range, and
- the relationship 0.4≦Wa/Wb≦0.7 is satisfied.
4 more elements
A golf club shaft having:
- a front tip end and a rear butt end, wherein the rear butt end is formed from a low elasticity prepreg material containing fibers with a fiber elastic modulus in the range 2 t/mm2 to 20 t/mm2,
- a shaft weight of 56 g or more, and
- a bending rigidity value EI at a point 630 mm from the shaft front end to the shaft rear end of 3.6 kgf m2 or less,
- wherein if the distance from the shaft front end to the shaft gravity center point is LG and the full length of the shaft is LS, then 0.54≦LG/LS≦0.65 is satisfied and
- wherein
- the shaft comprises a tubular body formed from multiple fiber reinforced resin layers of full axial length and at least one butt partial layer of partial axial length extending from the rear butt end, P2 is a point separated from the butt end by 250 millimeters, a range from point P2 to the butt end is defined as a specific butt range, Wa is the weight of the butt partial layer in the specific butt range, and Wb is the weight of the shaft in the specific butt range, and
- the relationship 0.4≦Wa/Wb≦0.7 is satisfied.
4 more elements
A golf club shaft having:
- a front tip end and a rear butt end,
- a shaft weight of 56 g or more, and
- a bending rigidity value EI at a point 630 mm from the shaft front end to the shaft rear end of 3.6 kgf·m2 or less,
- wherein if the distance from the shaft front end to the shaft gravity center point is LG and the full length of the shaft is LS, then 0.54≦LG/LS≦0.65 is satisfied, and
- wherein the shaft comprises a tubular body formed from multiple fiber reinforced resin layers of full axial length and at least one butt partial layer of partial axial length extending from the rear butt end, P2 is a point separated from the butt end by 250 millimeters, a range from point P2 to the butt end is defined as a specific butt range, Wa is the weight of the butt partial layer in the specific butt range, and Wb is the weight of the shaft in the specific butt range, and the relationship 0.4≦Wa/Wb≦0.7 is satisfied.
2 more elements
Dependencies are inferred from the claim text.