| 摘要 |
PURPOSE:To prevent the back flow of molten resin by using a system in which the starting position of injection is controlled to mutually couple a nozzle with a screw head during the stamping molding period in an injection molding machine for stamping molding. CONSTITUTION:During the stamping molding period, a nozzle 4 is contacted with the sprue 7b of molds 2, the screw 6 is advanced, molten resin is injected, and at the same time as the packing of the resin is finished, the starting point of injection, or the position of the screw 6 for weighing completion, is regulated to fit the convexed portion 9a of the screw head 9 into the concaved portion 4b of the nozzle 4 by a much as l1. Subsequently, stamping molding is made. In this case, the resin in the molds 2 is compressed by a great force resulting from the variations in the volume of the molds 2 and is ready to flow back into an injection cylinder 5 from the gate 7d, but the back flow is prevented by the close fitting of the concaved portion 4b with the convexed portion 9a. Good appearance molding with high accuracy and without sink caused by cooling can be attained. |
