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FEM Investigations for Practical Extrusion Issues

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FEM Investigations for Practical Extrusion Issues --- Extrusion Process for Complex 3-D Geometries; Pocket Designs of Die; Transverse Weld Phenomenon

Qiang Li, Chris Harris, Mark R. Jolly University of Birmingham, UK

Track: DIE DESIGN AND TECHNOLOGY - Finite Element Method

ABSTRACT --- Finite element method (FEM) has been widely accepted as an effective
tool for investigation of many extrusion issues. In this study, several important and
practical extrusion issues (extrusion process for a complex 3D geometry, pocket
designs of die and transverse weld phenomenon) were investigated by using FEM and
experimental method. It is clearly shown, for extrusions with complex geometry, that
with designed extrusion, the metal flow is inhomogeneous, and even slight
inhomogeneity of metal flow can significantly affect the final geometry shapes of
extrudates. Both FEM and experiment demonstrated that extrudate is bent and twisted.
The complex distortion patterns were analyzed in details and related to its cause:
inhomogeneous flow behavior. The influence of the pocket design parameters,
including pocket angle, size, geometry and offset on the metal flow, was systematically
investigated using FEM. It is shown that pocket angle plays an important role
influencing metal flow velocity while pocket volume has less effect on velocity. Different
geometry configurations have different effects on metal flow velocity and conical
pockets have the largest effect on increasing the flow velocity. Although step(s) reduce
the volume of dead metal zone and the pocket size of conventional square pockets,
this does not change metal flow velocity significantly. Offsets in the pocket have an
effect on velocity, causing bending of the extrudates. The investigation mainly focused
on developing a qualitative understanding of pocket designs. The metal flow patterns
and velocity profile around pockets have also been illustrated. For transverse welding
phenomenon, simulation results show that inhomogeneous metal flow occurred and
the welding pattern was revealed. The design parameters influencing the transverse
weld length were also investigated and discussed.

© Extrusion Technology for Aluminum Profiles Foundation (ET Foundation). All rights reserved. No part of The Proceedings may be reproduced in any form without the express written permission of the ET Foundation.