Screw elements with reduced sweep angle

摘要

The present invention relates to screw elements for multiscrew extruders with pairs of co-rotating and fully wiping screws, to the use of these screw elements in multiscrew extruders and to a method of generating screw elements according to the invention.

主权项

1. Screw elements for multiscrew extruders having a pair of barrels, the screw elements comprising
an intermeshing pair of screw elements, with paired co-rotating and fully wiping screw shafts, configured to be positioned within the pair of barrels, comprising a first screw element and a second screw element and having a number (Z) of screw flights indicative of a number of arcs of each screw element that are adapted to wipe an outer wall of each barrel when the intermeshing pair of screw elements are positioned within the pair of barrels, a centre distance (A) between the first screw element and the second screw element and an outer diameter (DE) of each screw element, wherein the number (Z) of screw flights for each screw element is at least two, wherein the sum of tip angles of the intermeshing pair of screw elements is greater than 0 and smaller than2⁢π-4⁢⁢Z⁢⁢arccos⁡(ADE), wherein a clearance is provided between screw profiles of the intermeshing pair of screw elements, wherein a generating screw profile of the first screw element and a generated screw profile of the second screw element each have a number of arcs, equal to 6*Z or more, with a radius larger than or equal to zero and smaller than or equal to the centre distance (A), and further wherein the arcs merge tangentially into each other at their end points.