| 摘要 |
PURPOSE:To easily and quickly block off a vent hole and consequently shorten the time necessary for changing material by a method wherein a divisible press pin is inserted in a vacuum box for exhaust, which is provided at the vent opening of a heating cylinder so as to block off the vent hole. CONSTITUTION:First, the driving of a plasticizing screw 2 is stopped. Secondly, a blocking pin 15 is removed from an insertion hole 8. Thirdly, a door 10 is opened. Fourthly, a press pin 14 is fitted to a communicating hole 6. Fifthly, a holding down part 14B is disengaged by rotating it from a fitting part 14A and, after that, inserted in the pin insertion hole 8 and at the same time its tip part is screwed to a blind hole 8A. Thus, because the communicating hole 6 is blocked off with the fitting part 14, the material is changed by supplying raw material under high back pressure.
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