| 摘要 |
PURPOSE:To obtain a molded article having a stable quality, by a method wherein a pressure holding force is controlled when an injection stroke detection value at the certain period during an injection process is deviated from a standard value so as to be increased or decreased only for a set time corresponding to the deviation quantity. CONSTITUTION:An injection stroke quantity of a screw 3 varies with the elapse of time corresponding to an injection operation during an injection process. Accordingly, a gate 15 is closed usually and, when the stroke quantity reaches a state wherein a deviation value, deviated from the standard value set to an injection-stroke standard-value setting device 12, of the actual stroke detection value by a stroke sensor 8 may exert an important effect on the quality of a molded article, the gate 15 is opened on the basis of a set signal from a timing setting device 19. The gate 15 is held open only for the time set to a control time setting device 20. Therefore, by setting the appropriate control start point of time, a cushion quantity and the position of a screw at the point of time when the gate is sealed can be kept constant for a set control time at each shot, and a molded product having constant quality can be obtained.
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