| 摘要 |
PURPOSE:To prevent an internal stress from generating in a molded item during molding through a simple structure and mold the highly accurate molded item by a constitution wherein the vicinity of the molding surface, which corresponds to the thickness part of a molded item, of a movable mold, is made thin by removing excessive material to attain elastic deformation. CONSTITUTION:Respective parts near the molding surface 11a of a fixed bush 11 and near the molding surface 13a of a movable bush 13 are applied to so-called lightening work. The lightening work is applied to the peripheral edge parts of the molding surface 11a of the bush 11 and of the molding surface 13a of the bush 13 excluding the central parts of the respective molding surfaces 11a and 13a so as to make uniform the thickness between the molding surface 11a, 13a and a worked surface 19a, 20a. The thicknesses of the respective molding surfaces 11a and 13a are set to the thickness to thick as to be elastically deformed by the filling pressure of resin filled in a cavity 16. Since the molding surface parts, which form the thick thickness part, deform elastically pressure of the increase the volume within the cavity 16 by the filling pressure of the resin, and the molding surfaces restore their initial forms during cooling, the shrink characteristics at the surfaces in the thick thickness part and in a thin thickness part become uniform, resulting in developing no internal stress in a molded item.
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