| 摘要 |
PURPOSE:To prevent generation of defective gas accumulation by reducing dispersion of molded products and enabling uniform casting of a covering material into a cavity, by providing a covering material casting sprue at a specific angle to a mold split surface. CONSTITUTION:Spherical cores 7 are inserted as cores respectively into the central part of a plurality of spherical cavities 6 formed in a mold device to be divided into the top and bottom under a state where they are supported with a plurality of holding pins 4. Then along with injection of a covering material within the cavity 6 the holding pin 4 is pulled out through the cavity 6 prior to completion of the injection or upon the completion of the injection, the surface of the core 7 is coated with the covering material and a plurality of spheres are molded at a time. Hereupon, a covering material casting sprue 14 is provided on a split surface of a mold at an angle of at least 80 deg.. An angle of the sprue 14 to the split surface of the mold is most suitably almost perpendicular, that is, 90 deg.. Then it is preferable that resin is held under a fluid state by keeping a part or the whole of the sprue 14 warm at a temperature of at least the softening point of the resin (covering material) or heating. |
