Golf club shaft
View Patent ↗A shaft 6 is formed by a plurality of prepreg sheets s 1 , s 2 , s 3 , s 4 , s 5 , s 6 , s 7 , s 8 and s 9 . These prepreg sheets include full length sheets and partial sheets partially provided in the axial direction of the shaft. The full length sheets include a full length hoop sheet s 7 . The partial sheets include glass fiber reinforced sheets s 1 , s 4 . In the shaft 6 , a volume ratio Vf of the hoop layer in a specific tip part Tx is equal to or greater than 2.5% and less than 10%. The shaft 6 is lightweight and has a high degree of design freedom of a position of a center of gravity. The shaft 6 is excellent in strength of a tip part.
1. A golf club shaft comprising a plurality of prepreg sheets, wherein the prepreg sheets include a full length sheet, and a partial sheet partially provided in an axial direction of the shaft;
the full length prepreg sheet comprising a full length hoop sheet and a full length straight sheet, wherein the full length hoop sheet is a carbon fiber reinforced sheet and the full length straight sheet is a carbon fiber reinforced sheet; and
the partial prepreg sheet comprising a glass fiber reinforced sheet that is a uni-direction prepreg in which the glass fiber is oriented substantially in one direction, wherein the glass fiber reinforced sheet includes a tip glass fiber part positioned in the specific tip portion;
wherein a point separated by 90 mm from a tip end of the shaft is defined as T, with a region between the point T and the tip end of the shaft being defined as a specific tip portion, and
wherein a volume ratio Vf of a hoop layer in the specific tip portion is 2.5% or greater and less than 10%.
2. The golf club shaft according to claim 1 , wherein if a total thickness of the shaft is defined as Ts, and a portion having a thickness of Ts/3 from an inner surface of the shaft is defined as a specific inner part, the at least one glass fiber reinforced sheet is disposed in the specific inner part.
3. The golf club shaft according to claim 1 , wherein the glass fiber reinforced sheet includes an innermost layer forming part constituting an inner surface of the shaft.
4. The golf club shaft according to claim 1 , wherein a weight of the shaft is less than 50 g.
5. The golf club shaft according to claim 1 , wherein
the partial sheet includes a butt partial sheet;
the butt partial sheet forms a butt partial layer; and
a total weight of the butt partial layer is 5% by weight or greater and 50% by weight or less based on a weight of the shaft.
6. The golf club shaft according to claim 5 , wherein an axial direction length of the butt partial layer is 50 mm or greater and 500 mm or less.
7. The club shaft according to claim 1 , wherein the glass fiber reinforced sheet is straight sheet.
8. The golf club shaft according to claim 1 , wherein
the glass fiber reinforced sheet includes a tip partial sheet; and
an axial direction length of the glass fiber reinforced sheet as the tip partial sheet is 100 mm or greater and 350 mm or less.
9. The golf club shaft according to claim 1 , wherein the glass fiber reinforced sheet includes a butt partial sheet.
10. The golf club shaft according to claim 9 , wherein an axial direction length of the glass fiber reinforced sheet as the butt partial sheet has is 200 mm or greater and 450 mm or less.
11. The golf club shaft according to claim 1 , wherein an outer diameter of the specific tip portion is equal to or less than 10 mm.
12. The golf club shaft according to claim 1 , wherein an average thickness of the tip portion is 1.0 mm or greater and 1.8 mm or less.
13. The golf club shaft according to claim 1 , wherein a full length of the shaft is 41 inch or greater and 47 inch or less.
14. The golf club shaft according to claim 1 , wherein
if a distance between the tip of the shaft and a center of gravity of the shaft is defined as Lg, and a full length of the shaft is defined as Ls,
Lg/Ls is 0.54 or greater and 0.65 or less.