| 摘要 |
PROBLEM TO BE SOLVED: To provide a mold assembly for injection molding capable of accurately molding a plate-shaped part equipped with a cavity, a through-hole or the like without generating a weld line. SOLUTION: A molten resin is injected in the cavity 12 formed between a fixed cavity mold 7 and a movable core mold 11 of the mold assembly for injection molding to be spread throughout the cavity. Next, the flow of the molten resin is stopped and punching pins 23 and 24 are subsequently pushed in the cavity by the hydraulic cylinder 25 attached to a fixed mold part 2. After the molten resin is cured, the punching pins 23 and 24 are retracted from the cavity to perform mold opening and demolding. Through-hole parts are formed to the plate-shaped part by the punching pins 23 and 24. Since the projections for forming the through-holes for branching the flow of the molten resin in the cavity are not present when the molten resin is injected, the weld line does not appear on the surface of a molded article. As a result, the plate- shaped part equipped with the through-holes can be accurately injection-molded.
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