Method of evaluating restitution characteristic of golf club, system for evaluating restitution characteristic, and golf club

• US 20040005938A1
• Filed: 07/03/2002
• Published: 01/08/2004
• Est. Priority Date: 05/10/2001
• Status: Active Grant

• Current Assignee: Yokohama Rubber Company Limited
• Original Assignee: Yokohama Rubber Company Limited
• Inventors: Saegusa, Hiroshi, Ono, Kazunori
• Granted Patent: US 7,162,913 B2
• Time in Patent Office: Days
• US Class Current: 473/409
• CPC Class Codes: A63B 53/04 Heads
• CPC Class Codes: A63B 53/0466 wood-type
• CPC Class Codes: A63B 60/002 Resonance frequency related characteristics
• CPC Class Codes: A63B 60/42 Devices for measuring, verifying, correcting or customising the inherent characteristics of golf clubs, bats, rackets or the like, e.g. measuring the maximum torque a batting shaft can withstand
• CPC Class Codes: G01N 29/045 by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks measuring resonant frequency G01H13/00; measuring strength properties by application of mechanical stress G01N3/00
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14

Abstract

A method of evaluating restitution characteristics of a golf club head, a system for evaluating the restitution characteristics and a golf club, are provided in which a coefficient of restitution of a golf club head is inferred and obtained without disassembling the golf club by removing the golf club head away from a shaft and the coefficient of restitution may extremely easily be obtained for a short period of time. At first, an external force to a striking face of the golf club head is imparted to perform impact vibration. A response signal of the striking face under the impact vibration is acquired to obtain a resonant frequency of the striking face. A coefficient of restitution is calculated from the resonant frequency when the golf ball is struck by the striking face, whereby restitution characteristics of the golf club head are inferred and evaluated.

Claims

1. A method of evaluating restitution characteristics of a golf club head, comprising:

imparting an external impact force to a striking face of the golf club head at which a golf ball is hit to cause the striking face vibrating;

acquiring a response signal of the striking face which vibrates by the imparted impact force thereto to obtain a resonant frequency of the striking face from the acquired response signal; and

calculating a coefficient of restitution of the golf club head from the resonant frequency, the restitution being performed when a golf ball is struck by the striking face.

2. The method of evaluating restitution characteristics of a golf club head according to claim 1, wherein the resonant frequency is a first resonant frequency of the striking face.

3. The method of evaluation restitution characteristics of a golf club head according to claim 1, wherein the resonant frequency is a frequency from 3000 Hz to 7000 Hz.

4. The method of evaluating restitution characteristics of a golf club head according to claim 1, wherein the response signal is an acceleration signal of vibration of the striking face.

5. The method of evaluating restitution characteristics of a golf club head according to claim 4, wherein the impact force is imparted at multiple points on the striking face, a transfer function of the acceleration signal to a signal of the impact force is obtained at each of the points, and a peak frequency at which a peak generates at the same phase in any of the obtained transfer functions at the points is obtained as the first resonant frequency.

6. The method of evaluating restitution characteristics of a golf club head according to claim 4, wherein the impact force is imparted at multiple points on the striking face, and a vibration mode at the resonant frequency is obtained by using an amplitude of a transfer function of the acceleration signal to a signal of the impact force, to evaluate a distribution of the coefficient of restitution of the striking face.

7. The method of evaluating restitution characteristics of a golf club head according to claim 1, wherein the response signal is a sound pressure signal of the striking face.

8. A system for evaluating restitution characteristics of a golf club head, comprising:

an input device which acquires a response signal of a striking face of the golf club head, the striking face vibrating by an imparted impact force thereto;

an analysis unit which obtains a resonant frequency of the striking face from the acquired response signal; and

a calculating unit which calculates a coefficient of restitution of the golf club head, the restitution being performed when a golf ball is struck by the striking face.

9. The system according to claim 8, wherein the response signal is an acceleration signal of vibration of the striking face.

10. The system according to claim 8, wherein the response signal is a sound pressure signal of the striking face.

11. The system according to claim 8, the input device, the analysis unit and the calculating unit were integrated into a mobile computer.

12. A golf club, in which a restitution characteristics of a golf club head has been evaluated by using a method, comprising:

imparting an external impact force to a striking face of the golf club head at which a golf ball is hit to cause the striking face vibrating;

acquiring a response signal of the striking face which vibrates by the imparted impact force thereto to obtain a resonant frequency of the striking face from the acquired response signal; and

calculating a coefficient of restitution of the golf club head from the resonant frequency, the restitution being performed when a golf ball is struck by the striking face.