| 摘要 |
PURPOSE:To prevent flashes from generating at an end part of filling and a round hole part of a molded product by acting surplus dwell pressure upon molten resin before its solidification, by a method wherein peak pressure of the molten resin on the inside of a mold is eliminated by reducing an opening area of a nozzle before starting of dwell and a gradient is controlled through stepwise changeover by controlling a flow. CONSTITUTION:A measured screw position S1 detected by a screw position detector 21 and a set up screw position S2 of dwell starting set up by a screw position setting instrument 31 are compared with each other by a first comparator 32. A measured opening V1 detected by a nozzle valve opening detector 25 and a set up opening V0 before dwell are compared with each other by a second comparator 34. When both are coincident with each other, a command is given to a dwell nozzle valve opening setting instrument 35 and dwell time setting instrument 36. The opening is made to be a dwell opening Vp by applying a control current to a proportional solenoid 17 from the setting instrument 35. On the one hand, the command is given to a dwell pressure setting instrument 37 from the dwell time setting instrument 36 and set up pressure is made to be preset pressure by applying the control current to a control part 13a of a pressure control valve 13, through which pressure in the inside of an extension chamber 11 of an injection cylinder 7 is changed.
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