Spiral fed multi-layer tubular die

Abstract From the Canadian patent

An extrusion die apparatus for extruding a multiple layer tubular product comprising an elongated cylindrical mandrel and a plurality of annular die elements mounted co-axially one behind the other on the mandrel forming contiguous annular thickness control passages between the die elements and the mandrel. The die elements have inner and outer conical surfaces inclined rearwardly at a predetermined angle with respect to he longitudinal axis of the mandrel. The die elements are nested together with the outer conical surfaces of one die element facing the inner conical surfaces of an adjacent die element. The inner and outer conical surfaces form conical passages therebetween which …