Berstorff Gmbh

Kraussmaffei Berstorff Gmbh

Berstoff Gmbh

Michael Behling

Volker Wesling

Gerhard Scheel

Uwe Motzkau

Ralf J Dahl

A wearing body or bushing having an axial twin borehole for receiving a twin screw for extruding meltable material, in particular plastic. In order to avoid cracking and to save material, the wearing body has a radial cross section with an outer contour, which is convexly curved over the entire circumference and is in the form of an oval, and with first and second axes of symmetry, which run perpendicularly to one another and define a point of intersection which lies on the extrusion axis. The width of the oval on the first axis of symmetry is greater than the height of the oval on the second axis of symmetry.

Wearing body for receiving a twin screw for extruding meltable material

An extruder screw includes an extruder shaft and at least one extruder segment. The extruder shaft has a prismatic mandrel having external teeth and a longitudinal mandrel axis. The extruder segment has internal teeth and a longitudinal internal-teeth axis and can be slid onto the mandrel, such that the extruder segment can be connected to the mandrel for rotation therewith. The internal teeth have a profile having a meshing profile and, in an inner area between the first and second end faces of the extruder segment, include a prismatic main profile that has a main cross-section. Furthermore, the internal teeth of the extruder segment have an edge profile adjacent to at least one end face of the extruder segment, which edge profile has a smaller edge cross-section than the main profile at least in the area of the meshing profile.

Extruder screw, extruder, and method for producing an extruder screw

A process for producing a barrel for a twin-screw extruder with intermeshing screws from a steel block, wherein the barrel has a wear resistant inner surface, includes producing two partially intersecting bores passing completely through the steel block, the two intersecting bores forming a spectacle-shaped bore having narrowed regions where the two intersecting bores intersect, and hardening an inner surface of the spectacle-shaped bore with essentially constant depth of penetration by passing an inductor through the spectacle-shaped bore from one end to the other, the inductor is smaller than but having approximately the same shape as the inner contour of the spectacle-shaped bore and is configured such that less energy for heating the inner surface of the spectacle-shaped bore is delivered in the vicinity of the two narrowed regions of the spectacle-shaped bore by the longitudinal sections on the periphery of the inductor than in regions on the inner contour remote from the narrowed regions.

Production of a cylindrical housing for a double screw extruder

A cylinder assembly for a twin-screw extruder includes a cylinder forming an extrusion space and a hollow-cylinder mantle surrounding the cylinder and having a smooth inner surface. At least one channel is made in the shape of a helix in the longitudinal direction on the outside of the cylinder. The at least one channel is connected to an intake and outlet for conducting a tempering medium. The at least one channel is made by a winding-vortex process and the at least one channel is closed by the hollow-cylinder mantle. The cycle depth of the at least one channel in the radial direction changes over the circumference of the cylinder such that it is greatest in regions where the original wall thickness of the cylinder is greatest, and that it is smallest in the regions where the original wall thickness of the cylinder is also smallest.

Cylinder for a twin-screw extruder with a helical channel of varying depth

An extruder for polymer melts, with an extrusion space arranged in an extruder barrel and through which at least one extruder screw shank extends so that it can be rotated by a motor. The screw shank has at least one section in the form of a cylinder casing, the extrusion space having at least one barrel section which surrounds the cylinder casing in an essentially equidistant manner to form an encircling gap as a restricted flow zone (blister), in particular to set the pressure of the melt. The clearance of the encircling gap at the restricted flow zone can be changed in a specifically selective manner by externally adjustable force, with elastic deformation of the inside surface of the extrusion space and/or of the surface of the screw shank, by a hydraulic pressure chamber provided in the region of the restricted flow zone in the wall of the barrel section and/or in the least one screw shank. The pressure chamber has on the side facing the extrusion space a considerably smaller wall thickness (membrane wall) in comparison with the wall thickness of the extrusion space. A hydraulic pressure unit supplies the force for the surface deformation.

Extruder comprising blister mechanism

Apparatus for withdrawing at least one screw from the barrel of a screw extruder in conveying direction of the screw extruder, with the screw defining a longitudinal axis and terminating in a screw cap, includes at least one gripper having a free end for attachment of a pull mechanism and a grabbing end for interaction with an undercut of the screw cap. The grabbing end is formed with a plurality of radially resilient clamping segments for formation of a hollow cylinder having an inner diameter, which substantially corresponds to an outer diameter of the screw cap, and an outer diameter which is smaller than a diameter of a bore of the barrel. Each resilient clamping segment terminates in a beaded end which extends radially into the hollow cylinder for formation of a claw, wherein the beaded end has a wall thickness which is smaller than a difference between a radius of the barrel bore and an outer radius of the screw cap, and, in longitudinal direction of the gripper, a length which is smaller than a width of the undercut of the screw cap in longitudinal direction of the screw.

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Hameln, Germany

Michael Behling