| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for injection molding without impairing commodity value by effectively preventing a sink mark of a design surface side of a resin molding provided with a rib or a boss. SOLUTION: The method for injection molding comprises a mold clamping step of closing a mold 3 under a predetermined pressure, an injection step of injecting a molten thermoplastic resin in a cavity of the mold 3, a dwelling cooling step of cooling the resin injected in the mold 3 while dwelling it, and a mold opening step of opening the mold 3 to take out the solidified resin. In a process of the cooling step, a slide 61 of a sink mark preventing sliding mechanism 6 is protruded from a core surface 52 into the cavity and press injected into the cavity near a thick part of the resin. Thus, a reduced part of its volume due to the cooling of the thick part is covered to effectively prevent the sink mark.
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