| 摘要 |
PURPOSE:To obtain an article of injection molding with small shrinkage ratio and high dimensional accuracy by a method wherein the capacity of a cavity is enlarged just before the resin located in the gate part of a die is congealed and the melted new resin is introduced again into the gate part, thereby the forming pressure is transferred into the cavity. CONSTITUTION:A slide pin 12 which can be advanced, backed and engaged by an oil-hydraulic device 15 is projected initially by 1.0-2.5mm. inside a cavity 17 and the plasticized resin is filled therein through a gate 51, a small pass-hole. The slide pin 12 is backed just before the resin located in the part of the gate 51 is congealed and the gate 51 is closed, the plane surface of the cavity being made flat and the capacity of the cavity 17 being enlarged. The pressure of resin in the cavity 17 lowers and the resin congealing, located in the part of the gate 51, is pressed into the cavity 17, while the melted new resin is replaced in the part of the gate 51, which transmits the forming pressure into the cavity 17 through the gate 51, thereby the pressure inside the cavity 17 is raised. |
