| 摘要 |
PURPOSE:To enhance the molding efficiency by preventing the delay of a molding cycle due to the delay of cooling in the vicinity of the terminal of a hollow part in hollow injection molding introducing compressed gas into the molten resin injected into a mold cavity under pressure. CONSTITUTION:After compressed gas introduced under pressure is discharged from a hollow part 2, a small amt. of a molten resin is again injected into the hollow part 2 to make the pressure in the hollow part 2 slightly higher than atmospheric pressure and, after the hollow part 2 is hermetically closed, a hollow molded product is taken out of a mold 4. Since dwelling effect remains in the hollow molded product taken out of the mold 4, even when the hollow molded product is taken out in such a state that the cooling in the vicinity of the terminal 7 of the hollow part is insufficient, no sink is produced and the time required before the vicinity of the terminal 7 of the hollow part is perfectly cooled can be shortened. |
