Patent ID: 7284897

Claim:
An extruder for continuously working and/or processing flowable materials having at least three co-rotating shafts parallel to the extruder axis and disposed in a cavity of an extruder housing along a circle with the same central-angle distance, said shafts being equipped with elements including closely intermeshing screw elements whose end face is limited by circular arcs corresponding to an outside screw diameter, a screw core diameter and maximally a center distance of the screw elements, the extruder housing being provided on radially inner and outer sides of the cavity with concave circular segments parallel to the extruder axis, on which the screw elements are tightly guided, and the extruder having at one end at least one supply port leading to the cavity, wherein at least one said screw element comprises a conveying screw element, a passage screw element on a first one of said shafts formed by stock removal on a screw crest, screw core and/or screw flank, and a product flow inhibiting element on the first one of said shafts and spaced axially from the passage screw element is provided for inhibiting product flow in the flight of the passage screw element.