| 摘要 |
PURPOSE:To obtain the captioned produce which is free of deformation due to aging by a method wherein a plurality of gates are provided on a plate-like plane surface of a cavity in a plastic material injection-molding die so that thermal stress generated in the product is scattered. CONSTITUTION:The gates 22, 23 and 24 are arranged on the plate-like plane surface of the cavity 21 in the plastic material injection-molding die in such a manner that the flow resistances of a fused plastic material become substantially equal to one another at blocks 211, 212 and 213 of the cavity shown by the oblique lines during a process in which the fused plastic material flowing into the cavity in the directions of the arrows 25, 26 and 27 is filled in the cavity completely. In this case, it is preferable that the gates be arranged at some four to five places so that the lowering of the weld strength of the material is prevented and the warping of the product per unit length is minimized although the number of such gates is limited according to the size of the product. |
