| 摘要 |
<p>A closed space of an injection chamber is cleaned by a flow of new molten resin from an opening of a communicating path to prevent stagnation, resin leaking through a space formed between the peripheral wall of a cylinder and a head portion of an injection plunger is quickly discharged, and further, resistance to wear of the injection plunger is improved, so that the above-described actions are combined to make it possible to achieve injection molding of super high precision and super high quality. When the molten resin passes through the communicating path (30) and is injected into the injection chamber (17) through the opening (30a) in a state where a screw is retracted, a forward end face of the plunger (16f) forms a convex shape such as a cone (a), so that the resin from the opening (30a) generates a flow (C) and agitates and washes off residual resin being present in a closed space (A) disposed at a position opposite to a nozzle hole (27). On the other hand, there is a stepped portion (16c) consisting of a slight difference in stage between the head portion of the plunger (16a) and a handle portion (16b), the resin leaking and adhering to the peripheral wall (15a) of the cylinder is scratched off by the stepped portion (16c) when the plunger is retracted, and the resin is quickly discharged through a narrow space (S) formed between the peripheral wall and the handle portion. Furthermore, ceramic coating is applied to the head portion (16a) of the injection plunger.</p> |
