| 摘要 |
PURPOSE:To improve durability by simplifying the structure, by a method wherein a needle valve is provided movably longitudinally within a needle main body and communication and covering of molten resin and a pressurizing fluid are performed alternatively at the tip part and middle pat of the needle part. CONSTITUTION:When a screw 2 is moved forward, a needle valve 6 is moved backward in the opposite direction P with resin pressure, a resin inflow path 112 and an injection port 21 are communicated with each other and molten resin is injected into a mold. In this instance, communication of a feed passage 62 of the needle valve 6 with a communication path 13 is disconnected. Then when the screw 2 is moved backward, the needle valve 6 is moved in the direction P with energizing force of a spring 61, the tip part 6a abuts against and fits in a fringe part of a rear end of the injection port 21 and covers communication with a resin inflow path 12. In this instance, a feed passage 62 of the needle valve 6 is communicated with a feed passage 71 of a pressurizing fluid feed pipe 7 through a communicating path 113 and the pressurizing fluid is cast into the mold from an opening part of the tip of the needle valve 6 through the injection port 21. In this instance, the tip part 6a covers the communication of the resin inflow path 12 with the injection port 21. |
