New Spiral Shapes for Mandrel Dies

• Applicant: Professor Dr.-Ing. Reinhard Schiffers
• Subject Area: Plastics Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 490623099

For the extrusion of plastic products with annular cross sections, spiral mandrel dies are used when high quality demands are required for optical and mechanical properties. The design process of these dies is still dominated by heuristic methods, especially in the beginning. To get control over the vast quantity of variants, the geometric degrees of freedom have to be restricted first. This is achieved by defining basic parameters, such as the number of spirals, the spiral pitch angle, etc. To hedge these initial assumptions, a large range of die geometries must be calculated within a short time. In this phase, the use of three-dimensional numerical flow simulations is - if at all - only possible to a limited extent. Instead, numerical design programs are used, which calculate flow processes with some considerable simplifications. These programs are usually written specifically with one particular design case in mind, and therefore fairly inflexible to calculate different geometries. For axial spiral mandrel dies, this has led, among other things, to the fact that today's die geometry hardly differs from the concepts that were already developed at the end of the 1960s.Therefore, this research project aims to use the insights and conclusions gained through three-dimensional CFD simulations to improve the accuracy of pre-design programs on the one hand, and to systematically refine the basic shape of dies on the other.For this purpose, evaluation criteria for the results of numerical flow simulations of extrusion dies and the program-controlled optimization chain for extrusion tools, which were developed within the scope of DFG-funded projects at the Institute for Product Engineering (ipe) of the University of Duisburg-Essen, will be used.

• DFG Programme: Research Grants (Transfer Project)
• Application Partner: ETA Kunststofftechnologie GmbH