Inward Flow of Surface Materials at Back-Ends of Billets During Al-Extrusion, Part 1: A Finite Element Model

Abstract

In hot extrusion of Al-profiles, the billet-container boundary is characterized by the sticking condition. The outer surface layer of the billet is stuck to the container wall. At the back-end of the billet, the metal flow is complicated. The surface material, which is initially stuck to the wall, will be scraped away by the pad and flow inward into the billet. This kind of inward flow of surface material is usually undesirable and it is important to control such flow so that no surface material should be found in extruded profiles. In order to study this phenomenon, a model is proposed for the metal flow at the back-end, in which the rigid-plastic FEM is used. A computer program FEMBA has been developed based on the model. The simulation results are in qualitatively good agreement with experiments.