| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw that prevents vent-up in an injection molding machine where an inert gas is injected into a molten resin and after excess inert gas is exhausted, the molten resin is injected.SOLUTION: The target is a screw (3) of an injection molding machine (1) where the inside of a heating cylinder (2) is partitioned by a seal structure (27) provided in the screw (3) into a high pressure area (9) into which an inert gas is injected on the upstream side and a low pressure area (30) from which the inert gas is exhausted on the downstream side. In the present invention, a pressure drop reducing zone (35) is provided on the downstream side of the seal structure (27) of the screw (3). The pressure drop reducing zone (35) comprises two or more multiple flights, and a screw groove is formed with shallow groove parts (38) at two or more places in an axial direction. The inert gas is exhausted on the downstream side of the pressure drop reducing zone (35). |
