Prediction of curvature of an extruded bar with noncircular cross-section by a 3-D rigid-plastic finite element method

Abstract A method for simulating 3-D steady-state deformation in extrusion of a bar with an arbitrary cross-sectional shape is presented on the basis of the rigid-plastic finite element method. The 3-D element mesh for a billet flowing out through an arbitrarily shaped die opening is automatically generated. The curvature of the extruded billet due to the asymmetric shape of the die opening is treated by taking into account a nonuniform distribution of velocity at the exit boundary. The position of the die orifice is optimized in the finite element simulation to produce a straight bar. The curvatures of the products in the extrusion processes of T-shaped, L-shaped and right-square sections are predicted by the developed FEM simulator. The calculated curvature is in reasonable agreement with that for the extrusion experiment on plasticine billets. The effectiveness of the optimization method of the die orifice position for producing a straight bar is demonstrated in the extrusion process of an L-shaped section.