| 摘要 |
Apparatus for the injection molding of plastic materials comprising an elongated cylindrical housing and a screw-ram supported within a bore in the housing. Heating means are provided near the discharge end of the housing to heat and melt plastic material therein. Flights project radially from the screw-ram and extend for only part of its length, the screw-ram being mounted for rotary and reciprocatory movement within the bore. The screw-ram includes supporting bearing means for centering itself within the bore. Passage means which extend through the bearing means provides communication from behind the bearing to its front. Drive means serve to impart a rotary movement of the screw-ram and also to intermittently transmit axial movement to it in the direction of the discharge opening. The flights support the screw-ram within the bore in a feed zone remote from the discharge opening. A melting zone is provided in an annular space between the screw-ram and the bore wall extending from near the discharge opening toward the feed zone, the flights being disposed in said feed zone and terminating short of the melting zone. Dry, unplasticized granular pellets of plastic material are fed to the feed zone through an opening in the bore wall and are urged forward along a tortuous path through the flights and toward the bearing means into a heated zone where heat is applied to melt the plastic for injection into a mold.
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