| 摘要 |
PURPOSE: To prevent the silver streak in the vicinity of a center opening caused by the air reservoir of a sprue part at the time of injection filling while preventing a sprue from remaining in a fixed mold at the time of the release of the sprue in the molding of a disc molded product. CONSTITUTION: An air gap 13, the annular groove 14 communicating therewith and an air duct 17 are provided to a part where the fitting part of a male cutter 12 and a sprue bush 15 comes into contact with the sprue bush and an air changeover valve alternatively connecting a vacuum source or a compressed air source is provided to the air duct 17. The air gap 13 is connected to the vacuum source at the time of injection filling and connected to the compressed air source at the time of the release of a sprue. |
