Calibrating plastics hollow profile with inner and outer calibrators - the former extending into the latter and being surrounded by a pressure chamber

摘要

Device for calibrating a thermoplastic hollow profile comprises an inner calibrating mandrel connected to the working mandrel of an extruder, and an outer calibrating tool downstream of the inner calibrating mandrel; both calibrators being coolable. The inner calibrator extends, with an end section of its lengths into the outer calibrator and is surrounded, between the outer calibrator and the extruder die, by a pressure chamber which is subjected to hydraulic or pneumatic super-pressure. Thermoplastics profiles are produced in one single calibrating step, with very narrow dimensional tolerances.