Simulation of the process of transverse-forward extrusion with expansion

Abstract

Levchenko V. M., Aliiev I. S., Chepelenko O. Yu., Kartamyshev D. O., Malii O. G.
Simulation of the process of transverse-forward extrusion with expansion

Combined extrusion methods are a competitive solution for the production of complex-profiled and hollow parts in optimal power mode. By simulation of the combined transverse-forward extrusion process with using the energy method of kinematic modules, calculated correlations were obtained and an assessment of the influence of technological parameters on the deformation pressure was given. The possibility of considering the process of combined extrusion as sequentially composed one of two plane modules with the addition of normalized pressures of transverse and forward extrusion with expansion has been confirmed.

For the transverse extrusion module the correlations obtained by the upper bound method and showing results close to experimental data and similar solutions for problems of plane upsetting (final stage of die forming) and differing in two types of discontinuous velocity field were used. For a rectangular module of forward extrusion with expansion, a discontinuous velocity field was constructed and the correlation for calculating the pressure components on the velocity discontinuity lines was obtained. It has been found that there is an optimal value for the angle of the triangular module in the range of 42–45°, according to which it is recommended to tilt the semi-die wall. A graphical analysis of the dependence of the normalized combined extrusion pressure has allowed to identify that the relative parameters have the greatest influence on the pressure level: the height of the transverse extrusion deformation zone h/R₀ and the thickness of the ledge h/s, which characterize the degree of metal deformation.

The correlations that make it possible to evaluate the influence of the relative wall thickness of a hollow product h/s on the normalized deformation pressure were experimentally confirmed on workpieces made of aluminum alloy AA1135.