| 摘要 |
PROBLEM TO BE SOLVED: To shorten a time for gas discharge and a time for cooling moldings in the method for injection molding by gas injection and the mold used in the method. SOLUTION: A main cavity 21 is filled with a specified amount of a molten resin 80 and a gas is injected into the wall thickness of the molten resin 80 to form a hollow part 13. At the same time, a part of the molten resin 80 packed in the main cavity 21 is extruded into an overflow cavity 26 and even in this extruded molten resin, a continuously hollow part 21 is formed. After that, the volume of the overflow cavity 26 is increased by receding a movable core 50 inside the overflow cavity 26 and a resin layer 14 is disrupted by a decompression action ensuring from the increase in the volume of the cavity 26. Thus the residual gas left in the hollow part 13 after purging the gas is discharged all at the once to the outside of the mold. Consequently, it is achieved to shorten the time for gas discharge and the time for cooling moldings by cooling the moldings from inside the hollow part 21 with the help of the residual gas. |
