| 摘要 |
PROBLEM TO BE SOLVED: To mold a cast polyamide resin molding of a box shape like a comparatively thin thickness bucket free from inner defects by a method wherein a lock of a top force is opened within a specific time from a point of tithe when a load loaded on the top force is equalized to a dead weight of the top force itself, and dropped to progress polymerization under pressure. SOLUTION: A bottom force 15 in which polymerizable lactam liquid is casted, is raised to fit a top force 1, and the polymerizable lactam liquid is polymerized. At that time the top force 1 is firstly fixed to an upper support base under a state of being immersed in the polymerizable lactam liquid, and a load loaded on the top force 1 becomes less than a dead weight of the top force 1 by buoyancy. As polymerization proceeds, force attracting the top force is generated by polymerization shrinkage and crystallization shrinkage of the polymerizable lactam liquid, the load loaded on the top force 1 rises, and suddenly risen by exceeding the dead weight of the top force 1. In the case where its load satisfies a specific range, a solenoid valve of a lock control means is functioned to make the top force drop downward by the dead weight, and a pressurized state is formed to progress polymerization further. |
