VALVE GATE TYPE INJECTION MOLDING METHOD AND APPARATUS THEREFOR

摘要

A valve pin (4) for controlling an injection amount of molten resin is inserted into a cavity (13), and then the molten resin is injected through a gate (10) along a peripheral surface of the valve pin (4) into the cavity (13) to be dropped therein, and tip ends of the dropping molten resin are joined together at a bottom portion (13a) of the cavity (13) to form a hollow portion (S) between the valve pin (4) and the dropped molten resin. Then air is blown from the tip end of the valve pin (4) into the hollow portion (S) to inflate the hollow portion (S) to bring it into close contact with an inner peripheral surface of the cavity (13), and further the molten resin is cooled and solidified to provide a hollow molding (40). <IMAGE>