| 摘要 |
PURPOSE:To enable swift changeover of injection speed without a response lag in a changing part of a rising-up and falling-down of the injection speed, by a method wherein a nozzle opening area is controlled so that an injection speed becomes a preset speed when a screw position attains to a preset position, and at the same time pressing force of a screw is controlled so that differential pressure before and after the nozzle becomes a preset differential pressure. CONSTITUTION:A measured screw position detected by a screw position detecting instrument 21 and a screw position set up by a screw position setting instrument 31 are compared by a position comparator 33 with each other. When both of them coincide with each other, a control current is supplied to a comparative solenoid 17 by sending a signal so that an injection speed corresponds to the foregoing screw position set up in an injection speed setting instrument 32 beforehand. With this construction, varying control of an opening of a nozzle valve 14 is performed. A differential pressure before and after the nozzle valve 14 is operated through a detected value of a resin pressure detecting instrument 22 and an output signal from a pressure setting instrument 35 by a differential pressure operating circuit 34, and a signal is applied to a pressure setting instrument 35 so that the differential pressure becomes a set differential pressure. With this construction, the differential pressure before and after the nozzle valve 14 is controlled at a fixed level always.
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