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United States Patent 4938605
Douris , ê et al. July 3, 1990

Apparatus and method for mixing and continuous extrusion of a plastic mass

Friedrich July 3, 1990

Abstract

An apparatus for the mixing and continuous extrusion of a plastic mass having a first stage in which an intermittently operating mixer receives the starting materials batchwise and a second stage having a screw extruder which is supplied at periodic intervals, with material from the intermittent mixer. In order to provide a simple, inexpensive apparatus for two-stage mixing and extruding in which the full output of the first stage can be used and, independently of the state of the intermediate product, a continuous feed of material into the screw extruder of the second stage is effected. The second stage has mixing and kneading blades continuously rotating within a trough and an extrusion screw which extends along the bottom of the trough into an extrusion cylinder. A continuous drive motor for the extrusion screw is controlled so that the trough is always filled at least to 25% of its volume.