| 摘要 |
PURPOSE:To connect a second feed zone with a deaeration opening even if a screw is moved backward by a stroke at the time of plasticizing process by providing a plurality of deaeration openings in the axial direction of a heating cylinder within the range of movement of a feed zone in a second stage of a screw and making a plurality of deaeration openings respectively opening and closing. CONSTITUTION:Deaeration openings 12 and 13 are provided on a cylinder 11 in the axial direction in the range of movement of a second feed zone (f) of a screw 1. Said deaeration openings 12 and 13 are constituted of a small diameter dphi and a large diameter Dphi and plugs 16 and 17 coming in and out the small diameter (d) by means of actuators 14 and 15 to close the deaeration openings 12 and 13. One opening of either deaeration openings 12 and 13 is opened while the second feed zone (f) moves in the stroke S during the plasticizing process. When a screw 1 moves from the state A, that is a limit of moving forward, to the state B during the plasticizing process, the deaeration opening 12 is opened and the deaeration opening 13 is closed in the first stage, and the deaeration opening 12 is closed and the deaeration opening 13 is opened when the screw 1 passes the switchover position with the positioning devices 20 and 21 during the transfer of strokes S.
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