| 摘要 |
A screw extruder for processing polymeric plastics is described, which consists of a screw (2) with several processing zones (10 to 15) and a cylinder (1) with several sections (3 and 7 to 9), the length of which cylinder is matched to the length of the screw (2). The combination of measures to increase especially the flow of solid materials in the feed zone (10) is essential, e.g. the use of a replaceable grooved bush (4), and a shearing and mixing zone (12), which is described in detail, at the end of the compression zone (11), in which annular elements (18; 19), which are mutually supporting at their face sides, on the screw and in the related cylinder section cooperate in a special manner. Varied shearing and dispersion of the material flow, which is under the pressure of solid transport and enters into the mixing and shearing zone in a semiplastic state, achieves complete plastication thereof and extremely fine distribution of the components contained in the material flow. Each annular element (18; 19) has a plurality of chambers (21; 27) distributed on its interior and/or exterior circumference, which chambers are enclosed by helically extending, radial shear webs and axial delimiting webs (23; 29), so that the material flow is deflected several times in an approximately sinusoidal manner with mutual overlapping of the annular elements (18; 19) in the shearing and mixing zone (12) of the extruder in the direction of flow. With opposite pitch of the groove system, i.e. directed against the transport direction, the annular elements (18; 19) act in the sense of baffle elements. Any desired combinations are possible. <IMAGE>
|
