| 摘要 |
PURPOSE:To prevent a resin from flowing back at the time of injection compression molding by using a back flow preventing device having the second shaft which is capable of being freely advanced and retracted to adjust the volume of a runner part, and the first shaft which closed sprue part by a link mechanism. CONSTITUTION:The back flow preventing device 24 used for the injection compression molding of a resin lens or the like is comprised of the first shaft 1 connected to a cylinder 3 by the link mechanism, and the second shaft 2 also connected to the cylinder 3. In the condition where the first shaft 1 is retracted while the second shaft 2 is advanced to reduce the volume of the runner part 27, a molten resin is injected into a cavity 29 through the sprue part 26. Then, by advancing the cylinder 3, the second shaft 2 is retracted and the first shaft 1 is advanced to close the sprue part 26 by its end part, thereby contriving to prevent the back flow of resin. Thereafter, a cylinder 33 is operated to compress the resin in the cavity 29. |
