Method of producing hollow extruded profiles with limited shrinkage

摘要

1. Process for the extrusion of shrink-resistant hollow sections consisting of a thermoplastically deformable, impact-resistant plastics substance, preferably an elastomer-modified polyvinyl chloride substance, and having a profile calibrated externally within given tolerances, using a screw-type extrusion machine with an extrusion die, a calibrating device for calibrating the external profile of the section and a removal device, wherein, first, a hollow billet is produced at an adjustable extrusion die output speed, this billet then being calibrated by the calibrating tool, cooled and removed by the removal device at an adjustable removal speed, wherein the external dimensions of the profile of the section are, at the exit of the extrusion die, from about 2 to 5 % smaller than the dimensions of the calibrating input, and wherein the gap widths of the extrusion die exit producing the wall and cross-piece of the section are, in each case, uniformly between 20 and 40 % smaller than the desired wal thicknesses of the section, characterized in that extrusion die output speeds of between 50 and 180, preferably from 100 to 160, cm/minute are used and the removal speed after calibration is from 20 to 40 % less than the extrusion die output speed.