| 摘要 |
PROBLEM TO BE SOLVED: To certainly obtain a hollow product by injection molding even in a case larger than a specific pipe diameter by providing a tab or secondary runner gradually increased in its cross-sectional area from a resin gate to a cavity. SOLUTION: A molten resin impinges against the wall of a tab 2 from a resin gate 1 at a right angle to be prevented from the jetting of the resin and flows into a cavity 3 while wets the entire surface of the tab 2 by the gradual increase in the cross-sectional area of the tab 2 to fill the cavity 3 and a gas injection port 4 almost at the same time. The resin material is stretched while pressed to the surface of a cavity mold by the compressed gas injected from the gas injection port 4 to finally obtain a hollow molded product having a hollow part 5 and a thin-walled part 6 almost uniform in thickness. Therefore, when a pipe diameter is large, that is, 25mm, a mold for the injection molding of a hollow product capable of certainly obtaining a hollow product free from stripe patterns by injection molding can be provided. |
