Screw for a single screw extruder has an overflow flight with reduced height at an angle to a higher main flight

摘要

The screw has a helical main flight(10) and an overflow flight(20) of reduced height. The overflow flight runs at an angle to the main flight over at least one section of the latter. One flank of the main flight(10) is connected to the other flank of the same main flight by the overflow flight(20). Several overflow flights may connect the connect the same main flight and may have different heights. One section of the overflow flight runs parallel to the main flight and a further section is non-parallel. Sections between the main and overflow flights may have varying depth along the length of the flights. A screw may have several parallel main flights connected to each other by overflow flights. Overflow flights can include transverse grooves or openings or radial pins. Independent claims are included for: a) a single screw extruder with a barrel having feed and homogenizing zones and a screw which, in the homogenizing zone, has the claimed construction; b) a single screw extruder having a polygonal or mixing screw and a barrel with feed and homogenizing zones, in the latter of which at least one longitudinal groove runs along the inner wall.