Dunlop Sports Company Limited

Sri Sports Limited

Tatsuya Yashiki

Hirotaka Nakamura

To provide a golf club shaft that can provide a moderate rigidity and enhance an impact strength. A shaftincludes full length layers s, s, s, sand sprovided wholly in a longitudinal direction of the shaft, and tip end partial layers s, s, s, sand sprovided on a tip end part of the shaft. The full length layers include bias layers sand sand straight layers sand s. The tip end partial layer includes an inner glass fiber reinforced layer s, and an outer low elastic carbon fiber reinforced layer sor an outer glass fiber reinforced layer swhich is disposed outside the inner glass fiber reinforced layer s. The low elastic carbon fiber has a tensile elastic modulus of 22 ton/mmor less. In the shaft, a shaft weight in terms of 46 inches is 55 g or less.

Golf club shaft

A golf clubincludes a head, a shaftand a grip. The shaftincludes a plurality of layers, a tip end Tp and a butt end Bt. If a distance between a center of gravity of the shaft and the butt end Bt is defined as Lg (mm), a shaft full length is defined as Ls (mm), and a ratio of the distance Lg to the shaft full length Ls is defined as a ratio of the center of gravity of the shaft, the ratio of the center of gravity of the shaft is 44.5% or less. If a torsional rigidity at a point of 90 mm distant from the tip end Tp is defined as GJt (kgf&#xb7;m), and a torsional rigidity at a point of 210 mm distant from the butt end Bt is defined as GJb (kgf&#xb7;m), GJb/GJt is 5.5 or less.

Golf club

A shaftincludes a first butt partial sheet sand a second butt partial sheet sThe first butt partial sheet sincludes a first tapered part TPThe second butt partial sheet includes a second tapered part TPThe first butt partial sheet sand the second butt partial sheet ssatisfy the following (1) to (4). LLLLtand Ltare shown in FIG.L11&#x3e;L21 &#x2003;&#x2003;(1)1&#x2267;1&#xd7;&#x2003;&#x2003;(2)2&#x2267;2&#xd7;&#x2003;&#x2003;(3)21&#x2212;12&#x3c;50 &#x2003;&#x2003;(4)

[Object] To provide a golf club shaft that can provide a moderate rigidity and enhance an impact strength. [Solution] A shaftincludes full length layers s, s, s, sand sprovided wholly in a longitudinal direction of the shaft, and tip end partial layers s, s, s, sand sprovided on a tip end part of the shaft. The full length layers include bias layers sand sand straight layers sand s. The tip end partial layer includes an inner glass fiber reinforced layer s, and an outer low elastic carbon fiber reinforced layer sor an outer glass fiber reinforced layer swhich is disposed outside the inner glass fiber reinforced layer s. The low elastic carbon fiber has a tensile elastic modulus of 22 ton/mmor less. In the shaft, a shaft weight in terms of 46 inches is 55 g or less.

A golf club shaft is manufactured using a plurality of prepreg sheets ato a. The plurality of prepreg sheets ato aincludes full length sheets ato adisposed all over in a shaft axis direction and partial sheets aand apartially disposed in the shaft axis direction. The number of plies is substantially an integer in all the full length sheets ato a. The full length sheets ato ainclude four or more bias sheets ato a. Circumferential winding start positions of the bias sheets ato aare dispersed in four or more positions. Preferably, the circumferential winding start positions of the full length sheets ato aare dispersed in five or more positions.

A section where the tip side partial bias layer exists in an axis direction of the shaft is defined as a section T; a section where the back end side partial bias layer exists in the axis direction of the shaft is defined as a section B; and a shaft section inserted into a hosel of a head in the axis direction of the shaft is defined as a section H. A part of the section T overlaps with the section H. An overlapping section TB in which the section T overlaps with the section B exists. The whole overlapping section TB is located on a back end Bt side of the shaft from the section H. A center position Px of the overlapping section TB is located on a tip side of the shaft from a center position Pc of the shaft.

A golf club shaft has a tip end to which a golf club head is attached and a butt end to which a grip is attached, wherein the shaft is composed of a fiber reinforced resin having a fiber layer, the fiber layer contains a bias layer having bias fibers oriented at an angle with respect to an axial direction of the shaft, the bias layer includes a tip-side bias layer extending from the tip end toward the butt end and having a butt-side end terminating without reaching the butt end and a butt-side bias layer extending from the butt end toward the tip end and having a tip-side end terminating without reaching the tip end, and bias fibers in the tip-side bias layer has a tensile elastic modulus smaller than that of bias fibers of the butt-side bias layer.

Golf club shaft and golf club

A golf clubis provided with a head, a shaft, a grip, a head cavity bodymounted to the head, a grip cavity bodymounted to the grip, a head weightattachable to/detachable from the head cavity body, and a grip weightattachable to/detachable from the grip cavity body. A material of the grip cavity body is a polymer. A material of the head cavity body is a polymer. Preferably, the head weightis attachable to/detachable from the grip cavity body. Preferably, the grip weightis attachable to/detachable from the head cavity body. Preferably, in the golf club, a club mass can be adjusted without substantially changing a club balance.

Growing community of inventors

Kobe, Japan

Tatsuya Yashiki