| 摘要 |
PURPOSE:To obtain a molded form, having hard, smooth and beautiful surface as well as hollow and light body and strong against external pressure, by molding from a parison consisting of synthetic resin containing foaming agent. CONSTITUTION:Polystyrene resin, containing foaming agent, is extruded by a blow molding extruder 1 and a parison (p), extruded out of a dice 2 at the tip end of the extruder, is inserted into blow molding tools 3 and the molding tolls are clamped. Next, air is blown through a solenoid valve 4 and a nozzle 40, projected into the parison (p) in the tools, to form the parison (p) so as to be hollow along the blow molding tools 3. When about 2.5sec has elapsed after forming the parison (p) so as to be formed hollow, the inside of the blow molded form is evacuated through a pipe 60, connected to a vacuum pump by the solenoid valve 6, whereby the inside surface of the molded form is foamed. A foamed blow molded form 5, provided with a smooth skin 50 on the surface, can be obtained in such a manner. |
