| 摘要 |
PURPOSE:To provide a mold apparatus capable of molding a plastic concave lens of high quality by perfectly preventing the generation of weld at the time of the injection of a molten resin into a cavity. CONSTITUTION:An induction input 50 is allowed to advance and retreat from the position opposed to the gate 35 of the peripheral side part of the cavity 30 between a fixed input 6 and a movable input 13 with respect to the cavity 30 by a drive device 55 and a molten resin is injected into the cavity 30 in such a state that the induction input 50 is allowed to protrude. After the resin strikes against the leading end of the induction input 50, the induction input 50 is allowed to retreat to the peripheral side part of the cavity and, thereafter, the movable input 13 is allowed to advance. By this constitution, the resin penetrating in two directions of the central and peripheral parts of the cavity can fill the induction input retreat region in the cavity at the almost same time. Therefore, the generation of weld can be perfectly prevented. |
