| 摘要 |
PURPOSE:To obtain a plastic lens free of a weld line and inner strain and superior in optical pereformance by a method wherein a cavity surface for shaping a lens surface is heated to a melt resin flowable temperature just before a melt resin is charged. CONSTITUTION:A heat medium is continuously supplied to metal mold temperature control flow paths 16 drilled in a fixed mold 3 and a movable mold 4 which form a cavity 1. Thus, a melt resin charged in the cavity 1 is cooled by exchanging heat with the fixed mold 3 and the movable mold 4. Therefore, since a cavity molding surface is heated to a flowable temperature of a plastic lens molding material or higher just before the melt resin is charged by injection, the resin charged in the cavity, and kept in melt states reaches the top end of the cavity. In this manner, an inner strain, which has occurred in conventional practice, can be effectively prevented, and an occurrence of a weld line can be prevented. In addition, a plastic lens can be improved in optical performance. |
