Verfahrenstechnische Auslegung der Ausstoßzone eines konischen gleichlaufenden Doppelschneckenextruders

Translated title of the contribution: Mathematical process description of a corotating conical twin-screw extruder

Gregor Himmler

Research output: ThesisMaster's Thesis

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Extrusion is one of the most common processes to melt down polymers and get them into a desired form. After the extrusion process different kinds of tools are used to produce different product shapes, like pipes or granulate. Each of the used shaping tools has different geometries and therefore different pressure drops. Mixing virgin with recycled material has various benefits. Not only does it reduce the resulting cost of the product, but it also contributes saving the environment. The company Maschinen und Anlagenbau Schulz (M-A-S) developed a new kind of extruder. This extruder is a conical, corotating self-wiping twin screw extruder (new conical technology or NCT). The big geometries at the beginning of the screw enable processing even difficult to handle shapes (for example: Flakes). The smaller geometries towards the end of the screws also benefit pressure buildup properties at a decreased lenght. A thorough mathematical description of the processing properties helps changing geometry parameters accordingly. This work represents the beginning of this description, analyzing the pressure-, power- and flowproperties at the metering zone of the extruder. To calculate the geometry, the screws were split in small differential elements. In each of these elements, a parallel geometry was assumed. The whole geometry was then derived by summing up all these elements. The flow properties were calculated using iterations. First, the pressure at the end of the screw was calculated. The result was then compared with measured pressures. The flow was then changed accordingly, until the final pressure only deviated inside a set margin from the measured pressure. One problem of this method was partly the incompatibility of geometry and measured pressure. The pressure behavior was calculated again by dividing the screws into differential elements. The degree of filling was not taken into account, only the end pressure was measured. Further experiments are planned to ascertain the degree of filling. The needed power was calculated using the channel and the flight influences. Measuring the needed power of just one zone is not possible. Therefore the measured power consumption was reduced with a factor and then compared to the calculated power consumption.
Translated title of the contributionMathematical process description of a corotating conical twin-screw extruder
Original languageGerman
  • Schuschnigg, Stephan, Co-Supervisor (internal)
  • Holzer, Clemens, Supervisor (internal)
Award date26 Mar 2010
Publication statusPublished - 2010

Bibliographical note

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  • Process description Pressure Flow Power Conical Twin screw extruder Corotating Self-wiping

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