| 摘要 |
PURPOSE:To enable injection molding of high-precision molded product by a simple and low-cost mold, by a method wherein molten resin filled in the inside of a cavity through injection is compressed by a preset compression quantity through a shape memory effect of a member for compression operation. CONSTITUTION:When molten resin is injected into a cavity 2 through a sprue, runner 8 gate 9, then inserts 3, 5 each are moved in the direction enlarging capacity of the cavity 2 in the injection pressure of the molten resin, in injection molding of a high-precession optical parts such as plastic lens. As springs 14, 15 for compression operation has been kept deformed beforehand in a contracting direction, they don't block a movement of each of inserts 3, 5. Also temperatures of springs 14, 15 each for compression operation composed of a shape memory alloy are raised by that of the molten resin filled in the inside of the cavity 2. At the time of arrival fo the springs at the transformation point, the springs 14, 15 each for compression operation are restored in an extending direction by their shape memory effect. The resin of the inside of the cavity 2 is compressed through extension of the springs 14, 15 and molded into a molded product of a desired form. |
