| 摘要 |
PURPOSE:To stabilize molding conditions of each cavity by controlling an injection cylinder with filling pressure gradients and reserving pressure gradients in the cavities, in an injection molding utilizing a metallic die having a plurality of cavities of different configurations. CONSTITUTION:A molding metallic die 13 is consisting of a plurality of cavities 1a-1c having remarkably different configurations in thrickness, dimensions and the like. When molding condition is in a state wherein speed control is finished after biginning of injection, varying behaviors of resin pressures in respective cavities 1a-1c are detected by sensors 3a-3c for internal pressures of the cavities, and pressure and flow quantity of operation oil in an injection cylinder 13 is controlled through a controller 9 and a hydraulic pressure control valve 11 so as to trace a preset filling pressure ascending gradient. Further, after pressure reserving process is finished, the pressure and the flow quantity of the operation oil in the same cylinder is controlled in a same manner so that the varying behaviors of resin prssures in respective cavities will trace a preset reserved pressure descending gradient. According to this method, molding condition is controlled by tracing, thereby, a ratio of inferior molding may be reduced. |
