| 摘要 |
PURPOSE:To take out a lens free from flashes, by a method wherein at the time of molding of the lens, the molded between an upper and lower punches and the flashes streamed into a groove are turned forcibly through the upper and lower punch. CONSTITUTION:A sheet material 1 of thermoplastic resin for optics is fed between an upper and lower dies 2, 3 and held between both of them. An upper and lower molding actuators 13, 14 are actuated by a hydraulic controller 15, an upper and lower punches 4, 5 hold the sheet material 1 between them and an up-and-down oscillation through high frequency is applied to a sheet material through the upper and lower actuators 13, 14 and upper and lower punches 4, 5 by actuating oscillatable actuator 12. The upper and lower punches 4, 5 are pressed against the softened sheet material 1 while continuing an oscillation, the resin of the softened sheet material 1 flows concentrically into a groove 18 of the upper die 2 and upper punch 4, hardly accumulates in a clearance part and flashes 9 are formed in the groove 18. Then the upper and lower punches 4, 5 and lens 6 are turned at a time. With this turning, the lens 6 and flashes 9 are cut off from each other. |
