| 摘要 |
PROBLEM TO BE SOLVED: To obtain a precision molding resin scarcely having sink and having surface shape accuracy and dimensional accuracy by injecting gas from the flow end or middle of the molding resin. SOLUTION: Injection passages 5 for injecting gas introduced from a gas injection unit from the flow end of a molding resin are formed in molds 2a, 2b. The thermoplastic molding resin 3 supplied in advance into the hopper of an injection molding machine 1 is charged into the machine 1 and added into the molds 2a, 2b at an injection pressure of about 100 MPa for a prescribed time to implement the injection molding process of the resin. When the process is finished, approximately simultaneously, nitrogen gas is injected at a pressure of about 12 MPa for a prescribed time from the gas injection unit 5 by way of the passage 5. When a gas injection port is set in the flow of the resin, similar improvement effects are obtained.
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