PREPLASTICIZING TYPE INJECTION MOLDING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a preplasticizing type injection molding apparatus capable of preventing a defective molding from occurring without lowering a productive efficiency even if a continuous injection molding is carried out. SOLUTION: The preplasticizing type injection molding apparatus comprises a plasticizing section 20 for melting a resin material 13 supplied to a plasticizing cylinder 1 by rotating a screw 2 and an injection section 30 for injecting a metered molten resin material 13a into a mold 5 from a nozzle 6 at the top of an injection cylinder 3 owing to the advance of an injection plunger 4, and carries out a non-return action for preventing the molten resin material 13a from back flow on injection by closing a communicating pathway 14 from a plasticizing section 20 to an injection cylinder 3 by running a motion of the screw 2 forwarding or regression. An amount corresponding to the molten resin material 13a to be extruded to an injection cylinder 3 by advancing the screw 2 is sent backward by a reverse rotation of the screw 2. An amount corresponding to the molten resin material 13a pulled back from the injection cylinder 3 by a retreat of the screw 2 is sent forth by a regular rotation of the screw 2. COPYRIGHT: (C)2007,JPO&INPIT