| 摘要 |
PURPOSE:To obtain a method of injection molding plastics that is suitable for the mass production and suitable for producing a thick and large lens, a highly accurate plastic lens, etc., by providing a plurality of presses in addition to an injection molding machine, and using a plurality of molds that can be moved between the presses and the injection molding machine. CONSTITUTION:Each mold, that is, a rotary piece 1 is heated to a temperature in a temperature raising step suitable for molding. The rotary piece 1 is associated in a die set 2 attached to a molding machine, then with a clamping force applied, a resin is injected into its cavity by an injection cylinder 7, thereafter with the pressure released, it is moved on conveying rollers 5, and is associated in a re-pressing cooling die set 3, a compression pressure is again applied thereto by a press 27 while it is being cooled with the temperature controlled, and when the resin is cooled to solidify, a molded item 4 is formed in the rotary piece 1. By controlling the temperature gradient and the pressure when the cooling is carried out, the constriction and the internally stressed strain can be minimized. |
