| 摘要 |
PURPOSE:To improve a quality by preventing generation of voids of an injection molded product, by performing injection molding by depressurizing the inside of a cavity of a molding tool through suction of air of the same and the same is filled with gas of high solubility prior to injection of raw materials. CONSTITUTION:A vacuum pump 5 for depressurization in a cavity 3 formed by a molding bottom force 1 and molding top force 2 through suction of air of the same is connected with the cavity 3 through a valve 6 and a gas cylinder 7 is connected with the cavity 3 through a valve 8. To perform molding, valves 8, 9, 10 are closed, to begin with, and the inside of the cavity is depressurized by sucking the air of the same into a vacuum tank 4 through a vacuum pump 5 by opening the valve 6. Then the valve 6 is closed by opening the valve 8. With this construction, the cavity 3 is filled with gas of high solubility to raw materials in the gas cylinder 7 or that liquefied by pressure at the time of the molding. Then the raw materials are injected by opening the valves 9, 10 connecting with vent holes 9a, 10a.
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