2 THE ROLE OF THE MEASURING SYSTEM


The wall thickness measuring system is integrated into the production line and off ers additional control options during the extrusion process. The system measures important parameters such as diameter, wall thickness, ovality, and eccentricity.


Thin point control: This is where the pipe or tube is fi rst measured. The thinnest point defi nes the control section. The control system then calculates the new target value for the weight per meter and adjusts the haul-off speed, which also changes the wall thickness.


As a result, the system records fl uctuations in mass throughput and wall thickness so adjustments can be made. This ensures a further reduction in weight per meter. Wall thicknesses are sig- nifi cantly reduced while the minimum wall thickness is maintained.


1 Thermal die head centering


(Off set) weight per meter setpoint/superimposed control loop 3 FURTHER CONTROL OPTIONS


Thermal die head centering: Thermal die head centering for PVC pipes helps save material. The measurement data from the measuring system can be used as a starting point for manual pipe centering. The wall thickness distribution and pipe geometry are recorded by the measuring system and temperature adjustments are then made according to the optimum wall thickness and pipe geometry. New target values are defi ned and set for the temperature zones. The resulting change in melting speed in the heating zone reduces eccentricity. This leads to a further reduction in the weight per meter and optimal end products.


182.5° C 181.1° C 180.1° C 179.1° C 178.9° C 181.9° C 181.3° C 180.1° C


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