Thin-wall tubing - of soft thermoplastics with concave rollers in three planes for calibration

摘要

After extrusion, the tubing of soft PVC or polyethylene with a wall thickness 1 mm passes through compression rollers which cool the material to a shear modulus 108 dyn/cm2. The material then passes through an array of freely-rotating rollers to give a round profile through their concave profiles on three sides, the rollers being sand blasted or clad with PTFE to prevent surface markings. The purpose is to provide a calibration stage for soft thermoplastic tubing within thin walls.