Golf club head with flexure frequency matched with distortion-relaxation frequency of ball

• US 4,498,672 A
• Filed: 10/17/1983
• Issued: 02/12/1985
• Est. Priority Date: 04/05/1982
• Status: Expired due to Fees

• Current Assignee: John G. Bulla
• Original Assignee: John G. Bulla
• Inventors: Bulla, John G.
• Primary Examiner(s): Marlo, George J.
• Application Number:
  US06/542,479
• Time in Patent Office: 484 Days
• Field of Search: 273/78, 273/169, 273/DIG. 12, 273/170, 273/171, 273/172, 273/173
• US Class Current: 473/332
• CPC Class Codes: A63B 2209/00 Characteristics of used materials
• CPC Class Codes: A63B 53/04 Heads
• CPC Class Codes: A63B 53/0466 wood-type
• CPC Class Codes: A63B 60/00 Details or accessories of golf clubs, bats, rackets or the like
• CPC Class Codes: Y10S 273/12 Propylene

Abstract

Moldable golf club heads formed from a polypropylene plastic material encasing an elongated solid steel insert with a modulus of elasticity of approximately 30 million cycles per second and arranged with one end thereof extending one-eighth of an inch from the center of and substantially perpendicular to the striking face of the golf club head. The insert forms a part of the path for the shock wave produced when a ball having a resonant frequency of approximately 19 million cycles per second is struck by the head with the shock wave moving through the one-eighth of an inch of the plastic material, longitudinally through the insert to the head of the club and back the same path to point of impact whereby the density of the polypropylene and the insert being such that the recovery rate of flexure frequency of the head substantially equals the distortion frequency of the golf ball propelled from the club head.

Claims

1. A golf club head formed of a moldable plastic material comprising:

a body member formed of polypropylene having a sole, toe, heel and a planar striking face extending upwardly from said sole between said toe and heel and having a predetermined acute loft angle measured with respect to a plane passing through the axis of a shaft fastenable to said body member,

said body member being formed into a portion of an arcuate configuration with a plane surface thereof forming said striking face, and

an elongated solid steel insert with a modulus of elasticity of approximately 30 million cycles per second embedded in said body member and arranged so as to be completely surrounded by said plastic material with one end thereof spaced one-eighth of an inch from the center of and substantially perpendicular to said striking face,

said insert forming at least a part of the path for the shock wave produced when a ball having a resonant frequency of approximately 19 million cycles per second is struck by the head at approximately the center of said striking face, which shock wave moves through said one-eighth of an inch of the polypropylene material forming said body member, then longitudinally through said steel insert and the remainder of the polypropylene body member to the arcuate configuration of said body member and back the same path to the point of impact of the ball with the striking surface,

the density of the plastic material of said body member and said insert being such that the recovery rate of the flexure frequency of the head substantially equals the distortion-frequency of the golf ball when propelled from the face of the golf club head.

2. The golf club head set forth in claim 1 wherein:

said insert comprises a cylindrical configuration.

3. The golf club head set forth in claim 1 wherein:

said insert comprises a cylindrical configuration which is necked down between its ends.

4. The golf club head set forth in claim 3 wherein:

each half of said insert on each side of said necked down configuration is substantially identical.

5. The golf club head set forth in claim 3 wherein:

said insert comprises two integral substantially identical aligned portions.