| 摘要 |
PURPOSE:To obtain a disk molded piece having excellent optical characteristics that double refraction index at each part is equal, by cooling a periphery of a sprue and a tip of a male cutter during a period from about a time when an injection of a melted resin to a cavity is completed until a time when a forward movement of an ejector is completed. CONSTITUTION:At the time of molding, a fixed mold 10 and a movable mold 20 are closed together and a melted resin is injected into a cavity C of them from a nozzle N. A cooling medium is made to flow to cooling grooves 13 and 23 of mirror plates 12 and 22 of the fixed mold and the movable mold so as to cool the mirror faces to specific temperatures respectively. After a molded piece P in the cavity C is cooled, a male cutter 24 is made to proceed so as to cut a gate G. Thereafter, an ejector 25 is made to proceed so as to protrude the molded piece P from the cavity C. At that time, during a period from about a time when the injection of the melted resin into the cavity C is completed until a time when the forward movement of the ejector 25 is completed, the cooling medium is made to flow to a periphery of a sprue S and passages 17 and 27 at the tip of the male cutter 24. |
