A single-screw extruder for conveying and plasticizing a meltable material, including a screw and a heated cylinder, wherein the screw is rotatably held in the heated cylinder, the screw has a core and a helical main flight, which is at a first distance from the internal wall of the cylinder, a region of a transition zone and a melting zone has at least two successive, non-overlapping barrier portions, and a cylinder-side outside flight surface of one or more overflow flights is chamfered in full or in part over a flight width such that a conical gap that gets narrower in an overflow direction is formed between the internal wall of the cylinder and the cylinder-side outside flight surface.

A planetary roller extruder section forms a feed part of an extruder. The planetary roller extruder has an internally toothed housing and an externally toothed central spindle disposed centrally within and at a distance from the housing. Planetary spindles are arranged to rotate in a void between the central spindle and the housing. Each planetary spindle has an external toothing meshing with both the housing and the central spindle. At least one planetary spindle has two axially spaced areas with less than a full set of teeth. Those axially spaced areas include a first area having a first number of teeth and a second area having a second number of teeth. The second number of teeth is less than a full set of teeth and more than the first number of teeth.

A planetary roller extruder section forms a feed part of an extruder. The planetary roller extruder has an internally toothed housing and an externally toothed central spindle disposed centrally within and at a distance from the housing. Planetary spindles are arranged to rotate in a void between the central spindle and the housing. Each planetary spindle has an external toothing meshing with both the housing and the central spindle. At least one planetary spindle has two axially spaced areas with less than a full set of teeth. Those axially spaced areas include a first area having a first number of teeth and a second area having a second number of teeth. The second number of teeth is less than a full set of teeth and more than the first number of teeth.

A resin extruder capable of efficiently improving performance of kneading a resin material is provided. A resin extruder (1) according to one embodiment includes a cylinder (20), and a rotor-type screw (33) that is disposed in the cylinder (20) and kneads a resin material (51). In the rotor-type screw (33), a top part (33b) of a flight (33a) is formed in such a way that a gap between the top part (33b) and an inner surface of the cylinder (20) is changed from a front point to a rear point of the rotor-type screw in a rotation direction in a cross section that is vertical to an axial direction.

A resin extruder capable of efficiently improving performance of kneading a resin material is provided. A resin extruder (1) according to one embodiment includes a cylinder (20), and a rotor-type screw (33) that is disposed in the cylinder (20) and kneads a resin material (51). In the rotor-type screw (33), a top part (33b) of a flight (33a) is formed in such a way that a gap between the top part (33b) and an inner surface of the cylinder (20) is changed from a front point to a rear point of the rotor-type screw in a rotation direction in a cross section that is vertical to an axial direction.

A double-screw extruder for thermoplastic materials, with a first and a second extruder screw, whereby the extruder screws have an inlet and an outlet and a core, helically extending screw flights being arranged through the core from the inlet to the outlet, so that the screw peaks and valleys are circumferential, and the peaks of the first screw penetrate into the valleys of the second screw, and vice versa. The screw flights may have a geometry which is step-shaped in cross section, whereby the steps may be provided such that the stepped course of the peaks is congruent with the stepped course of the valleys.

High Specific Mechanical Energy extruder screw assemblies (14, 88, 98) and complete extruders (10, 86, 96) are provided, which include wide-flight intermediate screw sections (104) having axial flight widths greater than the flight widths of the inlet and outlet screw sections (102, 106) on opposite sides of the intermediate sections (104). The intermediate sections (104) provide increased friction and shear serving to enhance the SMEs imparted to comestible food materials during processing thereof.

High Specific Mechanical Energy extruder screw assemblies (14, 88, 98) and complete extruders (10, 86, 96) are provided, which include wide-flight intermediate screw sections (104) having axial flight widths greater than the flight widths of the inlet and outlet screw sections (102, 106) on opposite sides of the intermediate sections (104). The intermediate sections (104) provide increased friction and shear serving to enhance the SMEs imparted to comestible food materials during processing thereof.

A screw for a plasticating apparatus has one or more helical flights. A portion of the screw has a plurality of advancing grooves arranged in a noncontinuous helix cut in the screw. The advancing grooves are dimensioned to receive material therein as the material is conveyed through the barrel. The screw has a plurality of noncontinuous cross-cut grooves traversing one or more of the advancing grooves. The cross-cut grooves have a second helix angle greater than the first helix angle and less than ninety degrees; and/or one or more of the cross-cut grooves have a third helix angle of about ninety degrees.

A mixing section for an extrusion screw has an inlet end and an outlet end as well as alternating wiping lands and barrier lands. The wiping lands have a greater helix angle than the barrier lands. The wiping lands and the barrier lands define inlet channels which narrow toward the outlet end and outlet channels which widen toward the outlet end. A helical pattern of mixing channels is cut into the wiping lands and the barrier lands. The mixing channels may be oriented generally at approximately right angles to the wiping lands and the barrier lands. A portion of the extrudate encounters the inside wall surfaces of the mixing channels and changes direction which improves the mixing of the extrudate.