| 摘要 |
PURPOSE:To prevent the generation of a burr on the gate mark of a molded product and to reduce the damage of the molding surface of a gate part and that of a punch by excluding the molten resin between the leading end part of the punch and the surface of the cavity to a sprue or the cavity at the initial stage of the advance of the punch and shearing a disc gate by the punch when the advance stroke of the punch exceeds the thickness of the gate. CONSTITUTION:A molten resin passes through a sprue 1 and a disc gate 2 to fill a cavity 3 and a punch 4 is allowed to advance before the cooling and solidification of the molten resin are advanced. The molten resin in the gate 2 flows backward to the sprue 1 when the advance of the punch 4 is started and a part thereof further flows in the cavity 3 but, when the punch 4 advances over a distance equal to or more than the thickness of the gate 2, the gate 2 is closed from the cavity 3 to stop the inflow of the molten resin to the cavity 3, and the gate 2 and the cavity 3 are perfectly separated in a mold. When the part 8 of the mold is opened and a molded product and the gates protrude, the molded product and the gate are respectively released and the disc gate mark of the molded product becomes a smoothly finished state. |
