| 摘要 |
PURPOSE:To obtain the titled sphere having excellent appearance in good workability, by a method wherein two semi-spherical cores each having a concaved groove provided to the contact surface thereof are contacted to fill a mold and a molten resin is injected into the mold to form a skin layer while said groove is filled with the resin. CONSTITUTION:Two semi-spherical cores 1, 2, each of which has a sphape formed by splitting a sphere at the equator surface thereof and has concaved grooves 15, 25 provided to the split surface thereof so as to open the end parts of said grooves on the spherical surface of the semi-spherical core, are prepared by an injection molding method and, before perfectly cooled, the recessed part 16 and the protruded part 17 of the semi-spherical core 1 and the protruded part 27 and the recessed part 26 of the semi-spherical core 2 are inlaid to fabricate an integral core sphere. Subsequently, this core sphere is mounted in an injection mold and a molten resin is injected into the space formed between the surface of the core sphere and the surface of the mold to form a resin skin layer on the core sphere while the concaved grooves 15, 25 are filled with the resin to obtain a synthetic resin sphere for a gate ball. |
