Modelling the feeding and delay section of single screw extruders with non-isothermal models based on viscosity
Sprache des Vortragstitels:
Advances in Polymer Science and Technology (APST) 2
Sprache des Tagungstitel:
When designing single screw extruders to meet high quality requirements, the most important parameters are output and temperature. To be competitive, machine manufacturers must guarantee the production of high-quality products at high output rates with a broad processing window in terms of materials and processing parameters.
A single screw extruder must fulfil at least three basic functions: solid conveying, melting, and metering. In the solid conveying section, polymers are fed into the screw via a hopper, compacted into a tightly packed bed, and conveyed. When the melt film thickness exceeds the screw clearance, the melting section starts, and the melt is scraped off the barrel and collected in a melt pool. Calculating the solid conveying capacity of single screw extruders is a subject of international research. The solid conveying models can be divided into two basic classes: friction-based and viscosity-based models.
The presentation, will display the non-isothermal calculation of a solid conveying section based on viscosity, using viscous shear forces instead of frictional forces. The advantage of this model is that it does not require a frictional coefficient, which depends on temperature, pressure, velocity, and granular shape, and is difficult to determine in the extruder. Furthermore, a modified drag-induced melt removal model that builds upon that by Tadmor, and allows the delay section of a single screw extruder will be presented.