| 摘要 |
PURPOSE:To prevent a molten material from being mixed with another one in an adjacent passage and prevent a strength fall due to mixing of different constituents, by adjusting pressure distribution in the axial direction of a screw and adjust passag- to-passage pressure. CONSTITUTION:Small pellets are supplied from a chamber 1 of a hopper 3 and large pellets are supplied from another chamber 2. Both the chambers are partitioned from each other. Since the first passage 14 has a larger depth than the second passage 15, the large pellets do not enter into the first passage 14. At a melting section port, the first passage 14 is divided into the first and the second grooves 16, 17 to gradually increase the area, eliminate a pressure change in the passage and prevent molten resin from entering into the second passage. Since the pellets molten in the first groove 15a of the second passage 15 move into its second groove 15b beyond an accessory flight 20, the fluid pressure in the second passage 15 falls and the molten substance does not enter into the first passage. The resin having moved out of the first passage 18 passes through 7, 8, 10 and makes an inner layer A. An outer layer B is made by the second passage 21. |
