Single-screw extruder
AssigneeBattenfeld-Cincinnati Germany GmbH
InventorsMarkus Bornemann, Juergen Huegelmeyer
Life of this patent
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Abstract
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.
Claims11
A single-screw extruder for conveying and plasticizing a meltable material, comprising:
- 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, wherein the helical main flight is at a first distance from an internal wall of the cylinder and forms a screw duct together with the cylinder and the core of the screw,
- the screw comprises a solids conveying zone, a transition zone, a melting zone, and a melt conveying zone in accordance with changing states of matter of the meltable material,
- the first distance from the main flight to the internal wall of the cylinder in a region of the transition zone and the melting zone is configured such that melt is prevented from running over the main flight,
- the region of the transition zone and the melting zone has at least two successive, non-overlapping barrier portions,
- an overflow flight is arranged in each barrier portion, the overflow flights beginning from an active flank of the main flight, the active flank being defined by rotation of the screw, and ending at a passive flank of the main flight, the overflow flights thereby configured to provide at least three separate ducts, the at least three separate ducts being interconnected merely by a gap formed as a result of a second distance from the overflow flight to the internal wall of the cylinder,
- the second distance from the overflow flights to the internal wall of the cylinder in each barrier portion is greater than the first distance from the main flight to the internal wall in order to allow solids and/or melt to cross over,
- at least in a region of the first barrier portion, the internal wall of the cylinder is provided at least in part with either at least one cylinder groove extending in parallel with a longitudinal axis of the screw or a helically extending cylinder groove, 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 method for conveying and plasticizing a meltable material using a single-screw extruder in which a screw is rotatably held in a heated cylinder, the method comprising:
- providing the screw with a core and a helical main flight, wherein the helical main flight is at a first distance from an internal wall of the cylinder and forms a screw duct together with the cylinder and the core of the screw;
- providing the screw with a solids conveying zone, a transition zone, a melting zone, and a melt conveying zone in accordance with changing states of matter of the meltable material;
- configuring the first distance from the main flight to the internal wall of the cylinder in a region of the transition zone and the melting zone configured such that melt is prevented from running over the main flight;
- and
- transporting the meltable material along the screw duct from the solids conveying zone to the melt conveying zone and changing the meltable material from a solid into a paste-like melt in the process, wherein:
- in the transition zone and the melting zone, in which the cylinder region is fully or partly grooved, the meltable material passes over at least two separate, non-overlapping overflow flights, and
- a high solids fraction uniformly crosses over the first overflow flight over the entire length of a first barrier portion such that a solids-melt mixture is present in a subsequent duct formed downstream of the first overflow flight.
Dependencies are inferred from the claim text.