| 摘要 |
PROBLEM TO BE SOLVED: To avoid the occurrence of sinks due to ribs, improve the appearance and coefficient of hollowness of an molded article, and thus manufacture stably articles with uniform mechanical strength by preventing formation of unspecified ribs in a hollow part prior to withdrawal of a movable core. SOLUTION: A projection 9a is provided in a movable core 9, which serves to limit the expansion of pressurized fluid press-fed in a cavity in its projected state. In a projected state of the movable core 9, a hollow part 7 is formed in a molten resin 4 in part that is not limited by the projection 9a, following this, the hollow part is expanded in the wall thickness direction by withdrawing of the movable core 9 in order to be expanded substantially entirely to the part limited by the projection 9a. Thus, a stable distribution of the hollow part can be obtained without formation of unspecified ribs prior to withdrawal of the movable core 9. |
