Abstract: In the preparation and production of plastic materials by a continuously operating double shaft screw-type extruder, the efficiency of production often depends on good delivery of material to the extruder. In accordance with the invention for processing various types of plastic materials, a primary stage is mounted in a pressure-tight sealed manner on the housing of the extruder, the primary stage being formed by a vertical double conical container in which a pair of screw-type helices are rotatably supported and driven from above. The helices are connected to two replaceable feed elements at their lower ends so that delivery of material to the extruder is achieved without any intermediate dead spaces.

Abstract: A screw kneader for a plastic material in which a pair of longitudinal screws are rotatably mounted in respective bores for conveying plastic material through the kneader. The screws have spaced portions for advancing the plastic material from an inlet region to an outlet region and between the spaced portions is a section with reversed threads opposing plastic flow to effect mixing of the plastic material. The threads of the intermediate section are provided with openings to permit passage of up to 20% of said plastic material in the direction of advance. Transfer elements with helical threads connect opposite ends of the threads in the intermediate section with the threads of the inlet and outlet regions. The transfer elements of the two screws mutually engage one another to strip plastic material from one another and from the walls of the bores.

Abstract: A process for separating low molecular weight compounds from a crude polycaproamide melt comprises heat treating the melt in vacuo with superheated steam, in an extruder having a plurality of degassing zones, under precise conditions of temperature, pressure and configuration, such that the occurrence of side reactions and dehydration of the melt are substantially eliminated, the molecular weight of the polymer during the heat treatment in vacuo, during transport and subsequent processing remains substantially unchanged, a residual content of low molecular weight compounds of .ltoreq.1.8% is achieved, and the operating flexibility of the process is increased.

Abstract: A method and apparatus for pulverizing polymers. The apparatus comprises a hollow barrel within which at least one screw rotates. The interior of the hollow barrel is divided into a plurality of zones. Heating members are associated with a first of these zones and cooling members are associated with at least a second of these zones. Pre-crushing and pulverizing members are also disposed in said second zone. In the method, polymeric material is fed into the first zone of the hollow barrel and is fused therein. The fused material is then conveyed into the second zone wherein it is cooled, pre-crushed and pulverized. The powdered polymeric material is then discharged from said second zone. The method can therefore be effected continuously in a single apparatus.

Abstract: A method and apparatus for regulating a dose-charged twin-screw extrusion device so as to achieve optimum quantitative discharge of a material being extruded in an automatic manner. By monitoring the screw torque and the mass temperature and modifying the dosed supply of material and/or the screw speed in accordance with the monitored values, the optimum mode of operation is ensured for the extrusion device which fully utilizes the discharge capacity of the device without risking damage either to the extrusion device itself or to the material being extruded.