| 摘要 |
PURPOSE:To improve adhering property between an enclosed ball and the ball of a product and eliminate the bias of the enclosed ball to improve the rolling property of the product, by a method wherein an annular belt, prepared to penetrate into the whole periphery from surfaces P, L in the shape of a wedge, is provided in the cavity of a mold while the enclosed ball is made of synthetic resin. CONSTITUTION:When the enclosed ball 3 of synthetic resin is fitted into a spherical recess 5 in the cavity I1 of a mold, which is provided with the same diameter as the diameter of the enclosed ball 3, then, the mold having a cavity II is clamped and material is filled into the cavity by a pressure, the soft synthetic resin advances into a cavity over lines P, L to the tip end of the shape of wedge by the pressure and is molded so as to enclose the enclosed ball by the provision of the wedge type annular belt 4 whereby the resin is adhered to the enclosed ball to make a semi-product 7. The semi-produced ball 7 is fitted into a spherical recess 11 having the same diameter as the diameter of a product in a cavity IV, a cavity III 8 is mated, and the clamping of the mold is finished and the material is poured by pressure, then, the resin is filled so as to push the enclosed ball by a part, formed by the wedge type annular belt and enclosing the enclosed ball, whereby an adhesive degree may be improved further. The position of the center of the ball will never be deviated. |
