Golf club shaft
View Patent ↗A shaft of the present invention has a tip reinforcing layer. A prepreg s 9 for the tip reinforcing layer has a portion having a larger circumferential direction width Ws toward a tip side. The prepreg s 9 for the tip reinforcing layer has a thickness Pt of 0.06 mm or greater and 0.12 mm or less. An edge Ds of the tip reinforcing layer extends in an axial direction of the shaft while circulating in a circumferential direction of the shaft. An average value Ha of the five heights h 11 to h 15 is equal to or less than 0.03 mm.
1. A golf club shaft formed by curing a wound prepreg, the golf club shaft comprising:
a main body layer having a full length layer provided over a full length of the shaft, wherein when a layer positioned on the outermost side in the full length layer is defined as a full length outermost layer, the full length outermost layer has an exposure layer exposed to an outer surface of the shaft; and
a tip reinforcing layer provided on an outermost layer, wherein a prepreg for the tip reinforcing layer has a portion having a larger circumferential direction width toward a tip side and the prepreg for the tip reinforcing layer has a thickness Pt of 0.06 mm or greater and 0.12 mm or less and an edge of the tip reinforcing layer extends spirally,
wherein the golf club shaft is subjected to surface polishing so that a height h 1 of a level difference formed by the edge of the tip reinforcing layer satisfies the following item (a):
(a) when the height h 1 at a position placed apart from a tip by 60 mm is defined as h 11 ; the height h 1 at a position placed apart from the tip by 120 mm is defined as h 12 ; the height h 1 at a position placed apart from the tip by 180 mm is defined as h 13 ; the height h 1 at a position placed apart from the tip by 240 mm is defined as h 14 ; and the height h 1 at a position placed apart from the tip by 300 mm is defined as h 15 , an average value Ha of the heights h 11 to h 15 at the five positions is equal to or less than 0.03 mm, and
wherein, when a thickness of said exposure layer on the shaft before the surface polishing is defined as Qt 1 (mm) and an average thickness of the exposure layer after the surface polishing is defined as Qt 2 (mm), a ratio (Qt 2 /Qt 1 ) is equal to or greater than 0.6.
2. The golf club shaft according to claim 1 , wherein the golf club shaft is subjected to the surface polishing so that the height h 1 satisfies the following item (b):
(b) a ratio (Ha/Pt) is equal to or less than 0.5.
3. A method for making a golf club shaft according to claim 1 , comprising surface polishing a golf club shaft with a polishing agent having a particle size which is equal to or greater than F220 and equal to or less than F800.
4. The method for making a golf club shaft according to claim 3 , wherein the polishing is carried out with a polishing device using a polishing belt,
the polishing includes a first polishing step, and a second polishing step having a particle size of a polishing agent of the belt and/or a feed speed of the belt which are different from those of the first polishing step.
5. The method for making a golf club shaft according to claim 4 , wherein the particle size of the polishing agent at the first polishing step is coarser than the particle size of the polishing agent at the second polishing step.
6. The method for making a golf club shaft according to claim 5 , wherein the particle size of the polishing agent at the second polishing step is equal to or greater than F320 and equal to or less than F800.
7. The method for making a golf club shaft according to claim 4 , wherein the feed speed is changed while a full length of the shaft is polished, at the first polishing step or the second polishing step.
8. The method for making a golf club shaft according to claim 7 , wherein Vy is greater than Vx when a polishing speed in polishing the tip to a position Px is defined as Vx and a polishing speed in polishing the position Px to a butt is defined as Vy.
9. The method for making a golf club shaft according to claim 8 , wherein a distance between the tip and the position Px is defined as Lc (mm) and a length in the axial direction of the tip reinforcing layer is defined as Ls (mm), a difference (Lc−Ls) is equal to or greater than −200 and equal to or less than 200.
10. The method for making a golf club shaft according to claim 8 , wherein Vy is greater than Vx at the first polishing step.
11. The method for making a golf club shaft according to claim 10 , wherein a distance between the tip and the position Px is defined as Lc (mm) and a length in the axial direction of the tip reinforcing layer is defined as Ls (mm), a difference (Lc−Ls) is equal to or greater than −200 and equal to or less than 200.
12. The golf club shaft according to claim 1 , wherein a length Ls in the axial direction of the tip reinforcing layer is equal to or greater than 150 mm and equal to or less than 400 mm.
13. The golf club shaft according to claim 1 , wherein a full length of the shaft is equal to or greater than 1143 mm and equal to or less than 1499 mm.
14. The golf club shaft according to claim 1 , wherein a polishing amount of the full length layer is equal to or greater than 1 g and equal to or less than 3 g.
15. A golf club shaft formed by curing a wound prepreg, the golf club shaft comprising:
a main body layer having a full length layer provided over a full length of the shaft, wherein when a layer positioned on the outermost side in the full length layer is defined as a full length outermost layer, the full length outermost layer has an exposure layer exposed to an outer surface of the shaft; and
a tip reinforcing layer provided on an outermost layer, wherein a prepreg for the tip reinforcing layer has a portion having a larger circumferential direction width toward a tip side and the prepreg for the tip reinforcing layer has a thickness Pt of 0.06 mm or greater and 0.12 mm or less and an edge of the tip reinforcing layer extends spirally,
wherein the golf club shaft is subjected to surface polishing so that a height h 1 of a level difference formed by the edge of the tip reinforcing layer satisfies the following item (b):
(b) when the height h 1 at a position placed apart from a tip by 60 mm is defined as h 11 ; the height h 1 at a position placed apart from the tip by 120 mm is defined as h 12 ; the height h 1 at a position placed apart from the tip by 180 mm is defined as h 13 ; the height h 1 at a position placed apart from the tip by 240 mm is defined as h 14 ; the height h 1 at a position placed apart from the tip by 300 mm is defined as h 15 ; and an average value of the heights h 11 to h 15 at the five positions is defined as Ha, a ratio (Ha/Pt) is equal to or lower than 0.5, and
wherein, when a thickness of said exposure layer on the shaft before the surface polishing is defined as Qt 1 (mm) and an average thickness of the exposure layer after the surface polishing is defined as Qt 2 (mm), a ratio (Qt 2 /Qt 1 ) is equal to or greater than 0.6.
16. The golf club shaft according to claim 15 , wherein a polishing amount of the full length layer is equal to or greater than 1 g and equal to or less than 3 g.
17. A method for making a club shaft according to claim 15 , comprising surface polishing a golf club shaft with a polishing agent having a particle size which is equal to or greater than F220 and equal to or less than F800.