| 摘要 |
PURPOSE:To completely prevent the occurrence of sink and warping by a method in which an ejector pin is matched with the face of molds again at the completion of injection, and resin trapped at the tip of the ejector pin is pushed into the cavity. CONSTITUTION:When injection molding is made and a gata 9 is sealed up by resin cooled, the pressure of the resin becomes a fixed one. At the stage, the inside of the cavity is gradually cooled and the molten resin is also cooled, whereupon the volume of the resin begins to shrink but an ejector pin 11 is pushed back again by the force of a spring 14 to become matched with the mold face 3a. Accordingly, the resin trapped inbetween the ejector pin 11 and a through hole 3b formed in a movable side mold plate is again pushed back to the cavity 3. Thus, compensation is made for the shrinkage of molten resin. |
