MOLD FOR MOLDING OPTICAL DISC AND MOLDING OF OPTICAL DISC USING MOLD

摘要

PURPOSE:To enable stable continuous molding not generating the taking-out deficiency of a sprue especially coming into question. CONSTITUTION:A sprue bush 3 being an integrated product and having a straight cross section in a conventional mold is constituted of four parts connected through compression springs 3a in this mold and has a taper surface gradually becoming a small diameter toward a cavity. The sprue bush 3 before molding is held in an expanding direction by the action of the compression springs 3a and a resin guide passage is not formed. That is, the outer diameter of the sprue bush 3 has a taper shape gradually becoming a small diameter from a nozzle touch side to a cavity side and is divided into some parts in the longitudinal direction thereof.