| 摘要 |
PURPOSE: To obtain a resin brake piston of high quality while keeping good injection molding productivity by closing a mold in such a state that a movable core retreats from a predetermined position by a definite distance to inject and charge a resin into a cavity and subsequently advancing the movable core to the predetermined position. CONSTITUTION: A mold is closed in such a state that a movable core 15 retreats from a predetermined position by a definite distance to inject and charge a resin into a cavity. Subsequently, a gate seal pin 14 is allowed to advance to seal a gate and the movable core 15 is advanced to the predetermined position for constituting the final molded product shape of a brake piston. Next, the mold is opened and the movable core 15 is allowed to retreat and the product is taken out by an ejection pin. Herein, by allowing the piston of a hydraulic cylinder to advance and retreat, the movable core 15 is allowed to advance and retreat in arbitrary timing through the ejection plates 9, 10 for the hydraulic cylinder. |
