Method of manufacturing a golf ball

• US 6,200,512 B1
• Filed: 04/20/1999
• Issued: 03/13/2001
• Est. Priority Date: 04/20/1999
• Status: Expired due to Term

• Current Assignee: Callaway Golf Company
• Original Assignee: Callaway Golf Company
• Inventors: Marshall, Gary G., Felker, David L., Dewanjee, Pijush K.
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): Lee, Edmund H.
• Application Number:
  US09/296,197
• Time in Patent Office: 693 Days
• Field of Search: 264/250, 264/279.1, 264/248, 264/263, 264/46.4, 264/255, 264/DIG. 65, 473/373, 473/376
• US Class Current: 264/250
• CPC Class Codes: A63B 37/0003 Golf balls
• CPC Class Codes: A63B 37/0052 Liquid cores
• CPC Class Codes: A63B 37/0056 Hollow; Gas-filled
• CPC Class Codes: A63B 37/0064 Diameter
• CPC Class Codes: A63B 37/0065 Deflection or compression
• CPC Class Codes: A63B 37/0067 Weight; Mass
• CPC Class Codes: A63B 37/0075 Three piece balls, i.e. cover, intermediate layer and core
• CPC Class Codes: A63B 37/0076 Multi-piece balls, i.e. having two or more intermediate layers
• CPC Class Codes: A63B 45/00 Apparatus or methods for manufacturing balls working of plastics or substances in a plastic state B29
• CPC Class Codes: B29C 2045/14877 preheating or precooling the insert for non-deforming purposes
• CPC Class Codes: B29C 70/70 Completely encapsulating inserts B29C70/86 takes precedence
• CPC Class Codes: B29L 2031/54 Balls
• CPC Class Codes: B29L 2031/545 Football balls
• CPC Class Codes: Y10S 264/65 Processes of preheating prior to molding

Abstract

A method of manufacturing golf balls is disclosed that prevents the cover from cracking due to thermal expansion of the core during the cover formation process. The method includes the forming a core. One or more optional boundary layers can be applied to the surface of the core. The core and any boundary layers are pre-heated such that the core and any boundary layer undergo volumetric thermal expansion. After the pre-heating, the cover of the ball is formed over the core and any boundary layer. The method of the present invention also decreases cover molding cycle times for golf balls.

Claims

1. A method of manufacturing a golf ball comprising:

forming a golf ball precursor product, the golf ball precursor product having a first volume;

heating a golf ball precursor product such that the golf ball precursor product undergoes a predetermined volumetric thermal expansion of the first volume to create a thermally expanded golf ball precursor product,wherin the thermally expanded golf ball precursor product substantially prevents cracking of a cover upon application of the coverover the thermally expanded golf ball precursor product through an exothermic reaction or heated process; and

applying the cover over the thermally expanded golf ball precursor product through the exothermic reaction or the heated process.

2. The method according to claim 1 wherein the cover is applied through an exothermic reaction.

3. The method according to claim 1 wherein forming the golf ball precursor product comprises forming a core and applying at least one boundary layer over the core.

4. The method according to claim 1 wherein forming the golf ball precursor product comprises forming a core.

5. The method according to claim 1 wherein heating the golf ball precursor product comprises convection heating the golf ball precusor product at a temperature within the range of about 120°

F. to about 180°

F.

6. The method according to claim 1 wherein heating the golf ball precursor product comprises convection heating the golf ball precursor product at a temperature within the range of about 140°

F. to about 160°

F.

7. The method according to claim 1 wherein heating the golf ball precursor product comprises microwave heating the golf ball precursor product for a predetermined time period.

8. The method according to claim 3 wherein the at least one boundary layer comprises a thermoplastic elastomer.

9. The method according to claim 3 wherein the at least one boundary layer comprises an ionomer.

10. The method according to claim 1 wherein the cover comprises a thermoset material.

11. The method according to claim 5 wherein heating the golf ball precursor product comprises convection heating the golf ball precursor product for about one hour.

12. The method according to claim 1 wherein heating the golf ball precursor product comprises convection heating the golf ball precursor product at a temperature and for a time period sufficient to achieve at least a 1.2% volumetric thermal expansion of the golf ball precursor product.

13. The method according to claim 1 wherein heating the golf ball precursor product comprises heating the golf ball precursor product during and after forming the golf ball precursor product.

14. A method of manufacturing a golf ball comprising:

forming a core;

forming at least one boundary layer surrounding the core;

heating the core and the at least one boundary layer such that the core and the at least one boundary layer undergo a predetermined volumetric thermal expansion to create a thermally expanded core and a thermally expanded at least one boundary layer, wherein the thermally expanded core and the thermally expanded at least one boundary layer substantially prevent cracking of a cover upon application of the cover over the thermally expanded core and the thermally expanded at least one boundary layer through an exothermic reaction or heated process; and

applying the cover over the thermally expanded core and the thermally expanded at least one boundary layer through the exothermic reaction or the heated process.

15. The method according to claim 14 wherein heating the core and the at least one boundary layer comprises convection heating the core and the at least one boundary layer to a temperature within the range of about 120°

F. to about 180°

F.

16. The method according to claim 15 wherein heating the core and the at least one boundary layer comprises convection heating the core and the at least one boundary layer at temperature within the range of about 140°

F. to about 160°

F.

17. The method according to claim 15 wherein heating the core and the at least one boundary layer comprises convection heating the core and the at least one boundary layer for about one hour.

18. The method according to claim 14 wherein heating the core and the at least one boundary layer comprises heating the core and the at least one boundary layer at a temperature and for a time period sufficient to achieve at least a 1.2% volumetric thermal expansion of the core and the at least one boundary layer.

19. The method according to claim 14 wherein applying the cover comprises placing the thermally expanded core and the thermally expanded at least one boundary layer within a mold containing a polyurethane prepolymer material and a curing agent, and molding a thermosetting polyurethane cover over the core and at least one boundary layer.

20. The method according to claim 14 further comprising storing the thermally expanded core and at least one boundary layer in a hopper prior to transfer to a cover molding apparatus.

21. A method of manufacturing a golf ball comprising:

compression molding a core composed of a polybutadiene material;

injection molding a boundary layer composed of an ionomer blend material around the core to form a golf ball precursor product, the golf ball precursor product having a diameter ranging from 1.630 inch to 1.644 inch;

heating the golf ball precursor product to cause a predetermined volumetric thermal expansion of the golf ball precursor product to create a thermally expanded golf ball precursor product having at least a 1.29% volume increase of the golf ball precursor product, wherein the thermally expanded golf ball precursor product substantially prevents cracking of a thermosetting polyurethane cover upon application of the thermosetting polyurethane cover over the thermally expanded golf ball precursor product through an exothermic reaction; and

applying the thermosetting polyurethane cover to the thermally expanded golf ball precursor product through the exothermic reaction involving a polyurethane prepolymer and a curing agent.

22. The method according to claim 21 wherein the volume increase of the golf ball precursor product is between 1.3% and 2.41%.