Abstract: An extruder comprising several zones, including at least a plasticizing and mixing zone, a residence, mixing and cooling zone, and a mixing and cooling zone being constructed as planetary-roller extruders, the zones being substantially shut off from one another by blisters, and being connected to one another via melt pipes and intermediate pumps.

Abstract: A method and apparatus are provided for producing a mixture of plastics materials which are capable of being foamed with propellants. The method permits plastics materials, which require considerably different processing conditions, to be fused, homogenized and mixed with a propellant in an extruder. By feeding a high-molecular weight high-temperature resistant plastics material into the extruder through a first feed opening and subsequently feeding a low-molecular weight, low-temperature-resistant plastics material into the extruder through a second feed opening disposed downstream of the first feed opening but where the first plastics material is in a fused and homogeneous state and by introducing the propellant through a third feed opening downstream of the second feed opening, the desired homogenisation of the two plastics materials and propellant is ensured.

Abstract: An extrusion apparatus for the production of mixtures of molten synthetic material includes a gear pump which is provided in the flow of molten material. The gear pump comprises a housing and two meshing gear pump wheels. The line joining the centers of the two wheels extends at right angles to the central longitudinal axis of the hollow cylinder. Outlet and inlet openings are formed in the cylinder of the extrusion apparatus which lead directly into the gear pump housing into regions which are, respectively, upstream and downstream of the gear wheels. The major surfaces of the gear wheels are disposed horizontally relative to the central longitudinal axis of the hollow cylinder.

Abstract: An apparatus is disclosed for optimizing a method of producing a foam or expanded thermoplastic material, the material usually being mixed with a propellant. The apparatus comprises a filter unit which is disposed between and connects, a fusing and homogenizing extrusion device and a dynamic cooling device. The material is fed into the apparatus at one end of the extrusion device and passes sequentially through the extrusion device, the filter unit and the cooling device. Separate drive means are provided for the fusing and homogenizing extrusion device and the cooling device respectively. Both the extrusion device and the cooling device are disposed on a common longitudinal axis. The connections of the two devices to the filter unit is effected by means of flange mountings. The filter units also includes interchangeable filters which are traversed by the material. In the filter unit, the material flows through a conduit which flares conically outwardly from the filter to the inlet of the cooling device.

Abstract: In the production of foamed thermoplastic synthetic material, synthetic material is melted in a screw extruder and fluid propellant is injected into the molten sythetic material. The residence time of the molten mixture has a determining effect in regard to uniform distribution of the propellant and thus also in regard to the uniformity of the cell structure. In order to provide for homogeneous mixing of the propellant and uniform cooling of the molten mixture, without using an excessively long screw extruder, the screw extruder is provided, downstream of a melting region thereof and of an injection opening thereof through which propellant is introduced, with flow obstruction structure which is by-passed by static mixing structure disposed outside the screw extruder. The molten synthetic material is simultaneously mixed with the propellant and cooled in the static mixing structure.

Abstract: A temperable screw extruder for the continuous extrusion of thermoplastics materials wherein to increase the working and cooling of the material in the extruder without excessively increasing the length of the extruder means are provided to convey the material in a direction transverse to the axis of a main screw away from said axis and then to convey it back theretowards. Preferably said means comprises, located between the main screw and an extrusion outlet orifice, a transverse screw disposed in a transverse cylinder chamber to direct the plastics melt outwardly transversely to the axis of the main screw, a connection passage at the end of the transverse chamber to a downstream further transverse chamber having a further transverse screw therein to convey the material back towards the axis of the main screw.

Abstract: Apparatus for forming sheets of foamed synthetic plastics material, comprising a screw extruder, a nozzle head having an extrusion passage therein and a nozzle core positioned in the extrusion passage so as to form an annular nozzle, a cooled calibrating mandrel of a diameter larger than that of the annular nozzle, disposed downstream of the screw extruder having regard to the direction of extrusion and mounted on a stand, blowing means for applying internal pressure to an extruded tube between the annular nozzle and the calibrating mandrel to expand the extruded tube to the diameter of the calibrating mandrel, cutting apparatus for cutting open the increased-diameter cooled foamed plastics tube and apparatus for laying out flat the cut-open tube, wherein the nozzle core is rigidly connected to the stand of the calibrating mandrel and is connected to the inner wall of the extrusion passage by a single web aligned with the cutting apparatus whereby weakened and marked regions of the laid-flat cut-open tube are