Method for manufacturing golf ball

A method for manufacturing a two-piece core for a golf ball comprising:

• providing a mold for preliminary forming which defines a mold cavity, the mold having an upper mold and a lower mold, each of which is provided with a plurality of retractable or fixed holding pins protruding into the mold cavity;
• positioning a vulcanized inner core in the mold cavity by the protruded holding pins so as to define a shell space between the inner core and an inner surface of the mold cavity, each of the holding pins of the upper mold being arranged to protrude longer into the cavity than each of the holding pins of the lower mold;
• introducing an unvulcanized rubber material into the shell space so that a layer of unvulcanized rubber covers the inner core, forming an intermediate product;
• removing the intermediate product from the mold;
• placing the intermediate product into a vulcanization mold;
• and
• vulcanizing the layer of unvulcanized rubber.

A method for manufacturing a two-piece core for a golf ball comprising:

• providing a mold for preliminary forming which defines a mold cavity, said mold cavity communicating with a chamber containing a predetermined amount of unvulcanized rubber material, the mold having an upper mold and a lower mold, each of which is provided with a plurality of retractable or fixed holding pins protruding into the mold cavity;
• positioning a vulcanized inner core in the mold cavity by the protruded holding pins so as to define a shell space between the inner core and an inner surface of the mold cavity, each of the holding pins of the upper mold protruding into the cavity and each of the holding pins of the lower mold protruding into the cavity having a difference in protruding length ranging from 0.03 to 0.2 mm;
• applying pressure to the unvulcanized rubber material in the chamber to introduce the unvulcanized rubber material into the shell space so that a layer of unvulcanized rubber covers the inner core, forming an intermediate product;
• removing the intermediate product from the mold;
• placing the intermediate product into a vulcanization mold;
• and
• vulcanizing the layer of unvulcanized rubber material.

A method for manufacturing a two-piece core for a golf ball comprising:

• providing a mold for preliminary forming which defines a mold cavity, said mold cavity communicating with a chamber containing a predetermined amount of unvulcanized rubber material, the mold having an upper mold and a lower mold, each of which is provided with a plurality of retractable or fixed holding pins protruding into the mold cavity;
• positioning a vulcanized inner core in the mold cavity by the protruded holding pins so as to define a shell space between the inner core and an inner surface of the mold cavity, each of the holding pins of the upper mold being arranged to protrude longer into the cavity than each of the holding pins of the lower mold;
• applying pressure to the unvulcanized rubber material in the chamber to introduce the unvulcanized rubber material into the shell space so that a layer of unvulcanized rubber covers the inner core, forming an intermediate product;
• removing the intermediate product from the mold;
• placing the intermediate product into a vulcanization mold;
• and
• vulcanizing the layer of the unvulcanized rubber material.