| 摘要 |
A plasticizing and melting apparatus for granular synthetic plastic material has a heatable cylinder one end of which has an inlet opening for reception of granular material from an adjustable feeding unit which includes a shaker. The cylinder surrounds a rotary feed screw having a material advancing section in the region of the inlet opening, a first material densifying section immediately downstream of the advancing section, a collar which defines with the cylinder a narrow annular shearing gap immediately downstream of the first densifying section, a pressure relaxing section immediately downstream of the collar, and a second densifying section immediately downstream of the pressure relaxing section. The cylinder has one or more gas evacuating apertures which connect the interior of the cylinder with the atmosphere in the region surrounding the pressure relaxing section. The feed screw is movable axially between front and rear end positions, and the aperture or apertures are disposed in the region of the rear third of the pressure relaxing section when the feed screw assumes its front end position. This, combined with the feature that the length of the pressure relaxing section exceeds the distance between the two end positions of the feed screw, insures that the aperture or apertures can remove, from the area surrounding the pressure relaxing section, water vapors and/or other volatile constituents which are liberated in the interior of the cylinder as a result of plasticizing and melting of the plastic material.
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