| 摘要 |
PROBLEM TO BE SOLVED: To certainly and rapidly discharge the compressed gas within a hollow part. SOLUTION: Venting passages 3a, 3b are provided to a mold 1 separately from a gas supply passage supplying compressed gas into a cavity 2. A molten resin is injected into the cavity 2 and the compressed gas is supplied into the molten resin from the gas supply passage to form a hollow part 8 within a resin wall part 7 composed of the molten resin. When the temp. of the inner surface of the resin wall part 7 is equal to or higher than at least the m.p. of the molten resin, a pin 5 is allowed to advance into a cavity while a part of the side surface of the pin is allowed to interfere with a part of the resin wall part 7 extending in the advance and retreat direction of the pin 5 to provide a vent port to the resin wall part 7. After the resin wall part composed of the molten resin is cooled and solidified, the pin and a sleeve 4 are allowed to retreat and the compressed gas within the hollow part 8 is discharged from the venting passages 3a, 3b through the vent port. |
