| 摘要 |
PURPOSE:To prevent the generation of an impact due to discharge of a pressure oil by gradually discharging the pressure oil in a die clamping cylinder after the passage of the cooling time following the injection. CONSTITUTION:A step 8a is provided at the projection 8 on the front of a prefill valve 6 and a clearance S is formed between the outer diameter thereof 8a and the inner diameter of a rib 1a of a die clamping cylinder 1. Following the completion of the injection, upon the termination of a timer for setting cooling time, a pressure oil is fed to an oil hole 12 for opening the prefill and the prefill valve 6 is moved backward pressing a spring 7 for closing the prefill thereon. Consequently, the pressure oil in the die clamping cylinder tends to flow out through the clearance S as shown by figure 6. But with the clearance S, a pressure loss is caused to make the oil pressure discharge gradually. This prevents the working of such a large impact as posing a problem thereby enabling the lowering of pressure without generating noise and vibration in the opening of the die. |
