MOLD ASSEMBLY FOR INJECTION-MOLDING DISC BASE AND METHOD FOR INJECTION-MOLDING DISC BASE

摘要

PROBLEM TO BE SOLVED: To enable a sectional pattern which is a part of a movable half of a mold to be moved backward during injecting a synthetic resin, in a process to injection-mold an optical disc base using a toggle mechanism which moves the movable half to a cavity side half.;SOLUTION: A set cavity is formed of the sectional pattern 3B elastically supported with a specified space left to a mold base 3A fixed to a movable platen 2 mounted through the toggle mechanism 1 and the movable platen 2, a cavity-ring 15 elastically fitted to the sectional pattern 3B and the cavity side half 5. Further, a one shot worth of synthetic resin is injected into the set cavity and in this case, the set cavity is made an enlarged cavity by moving the movable half 3 backward until the movable half 3 comes into contact with the movable platen 2 by a synthetic resin injection force. After that, the movable half 3 in contact with the movable platen 2 is advanced as it is to compress the cavity down to the size of the set cavity. Thus the method for injection- molding the optical disc base is as described.;COPYRIGHT: (C)2003,JPO