Extrusion method, extruder and extruded product
AssigneeNextrom Holdings S.A.
InventorsKari Kirjavainen, Jyri Järvenkylä
Life of this patent
Estimating the term…
Abstract
An extruder according to the invention comprises at least two annular conical feed gaps (9) one within the other, formed between a rotatable rotor (1) and a stator (4, 5). At least some of the material to be extruded is subjected in the different feed gaps (9) of the extruder alternately to a higher pressure and then to a lower pressure. The rotor (1) or stator (4, 5) between the feed gaps (9) can then be balanced such that the pressure effect provides a hydrodynamic bearing, whereby, when the extruder is used, even at worst a very small force is exerted on die other bearings of the rotor (1) or stator (4, 5). By the method of the invention, a product can also be produced which contains cross-linked and at least partly oriented polyethylene.
Claims19
An extruder comprising rotor means and stator means for defining at least two annular conical feed gaps for receiving extrudable material and for extrusion of the material from the extruder, said rotor means comprising at least one rotatable rotor, said stator means comprising at least one stator, said at least one rotor or said at least one stator being disposed between the at least two annular feed gaps, at least one of the rotor or stator means comprising means for conveying at least part of the extrudable material received in the at least two feed gaps from a first part of the extruder to a second part of the extruder with the at least one rotor rotating at a circumferential speed and for subjecting the conveyed material alternately to an increase and decrease in pressure so as to promote a balancing of the at least one rotor or the at least one stator between the feed gaps, said means for conveying and subjecting comprising a plurality of grooves through which at least part of the conveyed material passes from a first of said plurality of grooves to a second of said plurality of grooves.
A method for extruding extrudable material comprising
- (a) providing an extruder comprising rotor means and stator means for defining at least two annular conical feed gaps for receiving the extrudable material and for extrusion of the material from the extruder, said rotor means comprising at least one rotor, said stator means comprising at least one stator, at least one of said rotor or stator means comprising means for conveying the extrudable material received in the at least two feed gaps from a first part of the extruder to a second part of the extruder with the rotor means rotating at a circumferential speed and for subjecting the conveyed material alternately to an increase and decrease in pressure so as to promote a balancing of the at least one rotor or the at least one stator between the at least two feed gaps, said means for conveying and subjecting comprising a plurality of grooves through which at least part of the conveyed material passes from a first of said plurality of grooves to a second of said plurality of grooves;
- and
- (b) supplying the extrudable material to the extruder with the rotor means rotating at the circumferential speed so as to cause the extrudable material to be conveyed from the first groove to the second groove, to be subjected to the increase and decrease in pressure and to be extruded from the extruder.
Dependencies are inferred from the claim text.