| 摘要 |
PURPOSE:To provide a method of manufacturing a hollow cylindrical molding of synthetic resin with a uniform thickness of an outer peripheral surface, high roundness and an excellent rotary performance due to the almost perfectly matching of a center of gravity with a center of rotation. CONSTITUTION:A method of manufacturing a hollow cylindrical molding of synthetic resin is composed of a step of injecting a molten synthetic resin to a columar molding chamber 2 formed so that a central shaft extends vertically in a die 1 from the bottom of the molding chamber 2, and a step of injecting a high pressure gas into an uncured molten synthetic resin in the molding chamber 2 from the bottom of the molding chamber 2 to mold a columnar hollow part 10 and at the same time, pressing the uncured molten synthetic resin to the inner surface of the molding chamber 2 and then curing the molten synthetic resin. |
