SHAFT FOR GOLF CLUB HAVING RIGIDITY IMPROVED AT INTERMEDIATE PART

• US 20140045605A1
• Filed: 03/14/2013
• Published: 02/13/2014
• Est. Priority Date: 08/09/2012
• Status: Active Grant

• Current Assignee: NHK Spring Company Limited
• Original Assignee: Kosuke Fujiwara, Naruki Yatsuda
• Inventors: FUJIWARA, Kosuke, YATSUDA, Naruki
• Granted Patent: US 9,295,888 B2
• Time in Patent Office: Days
• US Class Current: 473/318
• CPC Class Codes: A63B 2209/02 with reinforcing fibres, e.g. carbon, polyamide fibres
• CPC Class Codes: A63B 53/10 Non-metallic shafts
• CPC Class Codes: A63B 53/12 Metallic shafts
• CPC Class Codes: A63B 60/00 Details or accessories of golf clubs, bats, rackets or the like

Abstract

A shaft for a golf club is capable of hitting a higher ball and reducing a spin on the ball. The shaft has a distal part that is provided with a clubhead, a proximal part that is provided with a grip, an intermediate part arranged between the distal and proximal parts, and a thick part set to thicken a wall thickness of the intermediate part relative to the distal part, a reinforcing part set at the intermediate part, or a combination of the thick part and the reinforcing part. With this, the shaft improves a rigidity at the intermediate part so that a change in rigidity between the distal part and the intermediate part has an inflection point.

Claims

1. A shaft for a golf club, comprising:

a distal part that is provided with a clubhead;

a proximal part that is provided with a grip;

an intermediate part arranged between the distal and proximal parts; and

a thick part set to thicken a wall thickness of the intermediate part relative to the distal part, a reinforcing part set at the intermediate part, or a combination of the thick part and the reinforcing part, thereby improving a rigidity at the intermediate part so that a change in rigidity between the distal part and the intermediate part has an inflection point.

2. The shaft of claim 1, wherein the thick part or the reinforcing member is set within only the intermediate part.

3. The shaft of claim 2, wherein the thick part is formed to bulge outward from an outer periphery of the shaft, inward from an inner periphery of the shaft, or outward and inward from the outer periphery and the inner periphery.

4. The shaft of claim 2, wherein the thick part has end portions in a longitudinal direction of the shaft, each end portion gradually reducing a wall thickness of the thick part.

5. The shaft of claim 1, wherein the reinforcing part has a reinforcing member fit to an outer periphery or an inner periphery of the shaft.

6. The shaft of claim 5, wherein the reinforcing part has reinforcing members arranged in a longitudinal direction of the shaft and made of different materials.

7. The shaft of claim 5, wherein the combination of the thick part and the reinforcing part is set so that the thick part is formed to bulge outward from an outer periphery of the shaft or inward from an inner periphery of the shaft and the reinforcing part has a reinforcing member fit to the bulged thick part or to the outer or inner periphery of the shaft longitudinally corresponding to the bulged thick part.

8. The shaft of claim 1, wherein a material of the shaft is steel or fiber-reinforced plastic.

9. The shaft of claim 8, wherein:

the material of the shaft is steel,

the shaft has a stepped longitudinal sectional shape formed by processing a tapered material tube with a thickened part to be shaped into the thick part; and

the tapered material tube satisfies conditions of “

t1b times 1.05<

t1a<

t1b times 1.40,”

“

11<

L times 0.30,” and

“

12<

L times 0.75−

11”

in a case where “

L”

is an entire length between distal and proximal ends of the tapered material tube, “

11”

is a length between the distal end and one end of the thickened part, “

12”

is a length of the thickened part, “

t1a”

is a wall thickness of the thickened part, “

t1b”

is a wall thickness of a distal part of the tapered material tube.

10. The shaft of claim 9, wherein the tapered material tube further satisfies a condition of “

t1c times 1.05<

t1a<

t1c times 1.40”

in a case where “

t1c”

is a wall thickness of a proximal part of the tapered material tube.