| 摘要 |
PURPOSE:To increase molding effect by means of vacuum suction operation by opening a vacuum suction line end in a position close to a cavity of a fixed mold in a manner to be closed on the outer periphery of a sprue bush in the state of an injection nozzle advanced. CONSTITUTION:A sprue bush 3 incorporated in a fixed side mold 1' is inserted into a sprue bush inserting hole 4 opened in the center of the mold 1' slidably freely in the axial direction, and a winding spring 6 for return is brought into contact with a flange section 3' so that the sprue bush 3 cannot be sprung out in an ordinary state by means of a locating ring 7. An opening section 11 of the vacuum suction line 10 is disposed in a proper place close to a cavity 2 on the inner peripheral surface of the inserting hole 4 so that the opening section 11 is closed when the bush 3 is advanced by said opening section 11 and the end section outer periphery of the sprue bush 3, and an on-off valve in the vacuum suction line is constituted of said sprue bush 3 and the opening section 11 to the inserting hole 4. |
