Golf club shaft
View Patent ↗Provided is a fiber-reinforced golf club shaft with small cantilever bending displacement despite its light weight, and provided to exhibit a longer carry distance while showing excellent ball flight patterns regardless of the skills of a golfer. The golf club shaft configured to have a plurality of fiber-reinforced plastic layers made of resin and a fiber material, comprising: wherein formula (1) below is satisfied when the length of the golf club shaft is set as “L” (mm), the weight as “W” (g), and the displacement as “D” (mm) that is observed when a cantilever bending test is conducted by exerting a predetermined load in the vicinity of the tip end while supporting the butt end to measure the displacement at the tip end. 455≤ D +7.5× W ×(1168/ L )≤515 (1)
1. A golf club shaft configured to have a plurality of fiber-reinforced plastic layers comprising resin and a fiber material, the golf club shaft comprising:
a straight layer comprising the fiber material disposed at an orientation angle of −5 to +5 degrees relative to the longitudinal direction of the shaft;
a bias layer formed with an angle layer comprising the fiber material disposed at an orientation angle of −20 to −75 degrees relative to the longitudinal direction of the shaft and another angle layer comprising the fiber material disposed at an orientation angle of +20 to +75 degrees relative to the longitudinal direction of the shaft;
a smaller-diameter tip end on one end; and
a larger-diameter butt end on the other end,
wherein formula (1) below is satisfied when the length of the golf club shaft is set as “L” (mm), the weight as “W” (g), and the displacement as “D” (mm) that is observed when a cantilever bending test is conducted by following: a point 920 mm from the tip end of the shaft is supported from beneath, a point 150 mm toward the butt end from that point is supported from above, a load of 3.0 kgf is exerted on a point 10 mm from the tip end, and the displacement of the tip end is observed as the displacement (D),
455≤ D+ 7.5× W ×(1168/ L )≤515 (1)
wherein the golf club shaft is further comprising at least one fiber-reinforced plastic layer containing the fiber material with an elastic modulus of 300 to 460 GPa and a tensile strength of 5500 to 8500 MPa.
2. The golf club shaft according to claim 1 , wherein formula (2) below is satisfied when the length of the golf club shaft is set as “L” (mm) and the weight as “W” (g):
25≤ W ×(1168/ L )≤57 (2).
3. The golf club shaft according to claim 1 , wherein formulas (3) and (4) below are satisfied when the bending stiffness at a portion 525 mm from the tip end of the shaft is set as “EIb” (N·m 2 ) and the bending stiffness at a portion 175 mm from the butt end of the shaft is set as “EIc” (N·m 2 ):
21≤ EIb≤ 50 (3)
31≤ EIc≤ 70 (4).
4. The golf club shaft according to claim 1 , comprising a plurality of fiber-reinforced plastic layer comprising the fiber material with an elastic modulus of 300 to 460 GPa and a tensile strength of 5500 to 8500 MPa.
5. The golf club shaft according to claim 1 , comprising at least one fiber-reinforced plastic layer comprising the fiber material with an elastic modulus of 300 to 460 GPa and a tensile strength of 5500 to 8500 MPa among the fiber-reinforced plastic layers arranged in a region located at 30% of the entire shaft length from the tip end in the longitudinal direction of the shaft.
6. The golf club shaft according to claim 1 , comprising at least one fiber-reinforced plastic layer comprising the fiber material with an elastic modulus of 300 to 460 GPa and a tensile strength of 5500 to 8500 MPa among the fiber-reinforced plastic layers comprising the fiber material disposed at an orientation angle of −5 to +5 degrees in the longitudinal direction of the shaft.
7. The golf club shaft according to claim 1 , wherein formula (5) below is satisfied when the distance from the tip end to the gravity center of the shaft is set as “Lg” (mm) and the entire length of the shaft is set as “Ls” (mm):
54≤( Lg/Ls )×100≤62 (5).
8. The golf club shaft according to claim 1 , comprising a weight-adjustment layer “Wp” located on the butt-end side from the center of the shaft, wherein the weight-adjustment layer “Wp” is set to be 5 to 30% of the entire weight of the shaft.
9. The golf club shaft according to claim 1 , wherein formula (7) below is satisfied when the torque of the shaft is set as “Tq” (degrees):
4≤ Tq≤ 12 (7).
10. The golf club shaft according to claim 1 , comprising all of the fiber-reinforced plastic layer containing the fiber material with an elastic modulus of 300 to 460 GPa and a tensile strength of 5500 to 8500 MPa among the fiber-reinforced plastic layers containing the fiber material disposed at an orientation angle of −5 to +5 degrees in the longitudinal direction of the shaft.