Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A screw element for use as a kneading element in a plasticizing unit includes at least two kneading units which can be arranged on a common axis, for example a screw shaft. The kneading units have a geometry which is designed for attaining particularly good plasticization and reduced mechanical stress in such a way that the geometry of at least two successively arranged kneading units differs.

Abstract: 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.

Abstract: 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.

Abstract: The invention relates to a method and a device for inductive hardening of the interior surface of a spectacle shaped bore (2) in a cylinder housing (1) made of steel for a double screw extruder. According to the invention, the outer form of the electric inductor (3) corresponds approximately to the reduced interior contour of the spectacle shaped bore (2). Said inductor (3) is configured in such a manner that in the vicinity of the narrowing elements of the spectacle shaped bore (2) less energy is required for heating the inner surface in relation to the longitudinal section on the periphery of the inductor (3) than that is required for the areas of the inner surface which are remote from the narrowing elements (4a, 4b).

Abstract: 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.

Abstract: The invention relates to an extruder in particular for processing polymer melts, with an extrusion space (4) which is arranged in an extruder barrel and through which at least one extruder screw shank (2) extends in such a way that it can be rotated by a motor, said screw shank having on it at least one section (5) which is in the form of a cylinder casing, the extrusion space (4) having at least one barrel section (1) which surrounds in an essentially equidistant manner the at least one extruder screw shank (2) in the area of the at least one region (5) in the form of a cylinder casing to form an encircling gap (17) as a restricted flow zone (blister 15), in particular to set the pressure of the melt.

Abstract: 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.