A METHOD OF OPERATING AN INSTALLATION FOR THE PRODUCTION OF BIAXIALLY STRETCHED PLASTIC TUBES

摘要

Method of manufacturing biaxially stretched thermoplastic tubes using an installation which has a plastics extruder with open-loop or closed-loop control of its output and with a die head for extruding a high-viscosity initial tubing, a stretching mandrel and a speed-controllable take-off unit. In the region of the take-up part there is arranged a surrounding temperature-control bath for adjusting the temperature of the tube to stretching temperature, in the region of the take-off part there is arranged a cooling bath. In the region behind the cooling bath there is arranged a Raman spectrometer, which operates with laser waves. The frequency of the laser waves is adjusted appropriately for the plastic used and the energy of the laser waves is adjusted appropriately for the wall thickness of the tube produced, in such a way that the tube radiates not only the wave radiated in and scattered or reflected by the plastic but also at least one wave corresponding to a Raman spectral line. The degree of axial orientation of the molecules of the plastic is determined from characteristics of the wave scattered or reflected and/or radiated from the tube.