Extruder for scrap or impure material - passes melt through special aperture which only allows coarse particles to flow in core of melt so that surface of prod. has good finish

摘要

An extrusion tool is used for extruding principally plastic scrap with a flow pt. above 80 deg.C. which is contaminated with organic and/or inorganic impurities and which is flakes smaller than 6mm; at least part of the material has a flow pt. higher than the max. processing temp. of the prod.; the extruder outlet has an inlet (and can have a vertical bore) which is connected through a bore to a gap in a nozzle arrangement, and one area of the cross-section of the inlet bore is much greater than that of the nozzle. The ratio of cross-sectional areas of the inlet or manifold bore to a minimum for the flow bore and/or nozzle gap is at least 5:1 and is pref. 10:1. ADVANTAGE - The quality of surface finish in the extrusions produced is good enough to be universally applicable. The high densification factor applicable to the melt in the nozzle system is uninterrupted and no undesirable pressure drops occur. The non-fused scrap and impurities in the material are efficiently mixed in