| 摘要 |
PURPOSE:To obtain a disc base having excellent quality, by setting a mirror plate of a fixed mold being movable between a molding position regulating the thickness of a disc base and a retreating position to a mold main body under the condition where a mold for the disc base is registered and providing a cylinder means for moving the mirror plate of the fixed mold. CONSTITUTION:When an injection operation of a resin material 76 into a cavity is completed, a cylinder 68 is worked, its piston rod 70 is projected and a mirror plate 16 of the fixed side is forwarded with a distance (alpha) from a retreating position to a molding position where an open end face of a recessed part 60 of a rear face plate 58 is brought into contact with an apex face of an adjustable ring 44 on the side of a movable mold 12. The resin material 76 is filled into a cavity by this forwarding movement of the mirror plate 16 of the fixed side. After the resin material 76 is injected into the cavity like this, by forwarding thereafter the mirror plate 16 of the fixed side from the retreating position to the molding position, a disc plate having small internal stress, small birefringence and excellent quality can be obtained. |
