Patent ID: 7128464
Filing Date: 2006-10-31
Classification: B29B,B29C

Abstract:
1. A method for controlling a minimum level of pressure in a first half of a metering section, as seen in a transport direction, in a vented single-screw extruder or a cascade extruder during transport of a molten thermoplastic, the vented single-screw extruder or the cascade extruder in each case having a first screw section, a venting zone, a metering section and a measurement control circuit, which includes a first pressure-measuring sensor in the first half of the metering section, a first controller and a first actuator for influencing the pressure in the metering section, wherein the pressure is measured by the first pressure-measuring sensor and is set by the first controller and the first actuator such that a minimum level at a location of the measurement is between 0.1 and 10 bar, wherein the measurement control circuit includes a measurement amplifier that filters out the minimum level of the pressure and provides a value of the minimum level for control purposes.