| 摘要 |
PURPOSE:To prevent a sink on the surface of a lens from generating by shortening a molding cycle with a leap, by performing temperature control of a mold symmetrically in relation to an axis and accurately. CONSTITUTION:Molten plastic is injected by bringing a nozzle of a molding machine into contact with a hot runner bushing 12a. A hot runner nozzle 12 which has received an electric signal synchronized with the injection is heated by a built-in heater, the molten plastic is injected to a hot runner 18 through the tip 12b of the nozzle and arrives at a cavity 1. The molten plastic in the inside of the cavity 1 is pressed under predetermined pressure. A stationary mold 2 and movable mold 3 are separated from a parting 19 after cooling and curing, an extruding plate 20 is made to advance by an ejecting equipment and the plastic in the inside the cavity is released from the cavity 1 as a lens ball. As the stationary mold 2 and movable mold 3 are made into cylindrical forms which become concentric circles to the central axis of the cavity 1 respectively so that they become symmetrical in relation to the axis, a temperature distribution is hard to become nonsymmetric.
|
