Virtual tryout and optimization of the extrusion die for an aluminum profile with complex cross-sections

In this paper, the “trial-and-repair” process of the extrusion die is transferred from the workshop to the computer for a complex hollow aluminum profile used in high-speed trains. Firstly, a finite element (FE) model of the extrusion process is established with the arbitrary Lagrangian–Eulerian code HyperXtrude. To balance the material flow velocity in the die cavity, more than ten baffle plates are used and distributed in the welding chamber. Then, taking the exit velocity uniformity as the evaluating criterion, the initial extrusion die is modified by adjusting the shapes, the layout, and the heights of the baffle plates. Through a series of modifications, the velocity difference in the cross-section of the extrudate decreases significantly from 102.3 mm/s with the initial die to 26.6 mm/s with the final one. The local twisted or bent deformation of the extrudate is well controlled with the optimal die. Finally, a real extrusion die is manufactured and a practical profile is extruded. The difference in the rib thickness of the profile between the experimental measurements and desired dimensions is 0.12 mm, which satisfies the practical requirements. Moreover, the microstructures in the profile and its ribs are examined, and no heat defects are observed in the profile. Therefore, the virtual tryout of the extrusion die in this work are well verified, and the design rules of extrusion dies could provide theoretical guidance for practical repairs of complex extrusion dies in workshop.