Theoretical and Experimental Analyses for the Forward Extrusion of Nonsymmetric Sections

Abstract

A new generalized formulation for the analyses of the forward extrusion of nonsymmetric sections is presented in this article. In the formulation presented by the authors it is assumed that all points on the cross-section of the initial billet map to similar points on the final section of the extruded profile. The division of deforming region into subsections is done in such a way so that the theoretical concept for the material flow follows the real situation more closely than was done in previous works. This procedure provides a simpler and better way to tackle the extrusion of nonsymmetric shapes and could be used for shapes that could not been analyzed before. Based on the new formulation upper bound solutions were obtained. Using the present analysis the positioning of the die cavity was also optimized. Dies were designed and manufactured for the nonsymmetric C section profile, and experiments were carried out. Theoretical results were obtained for the extrusion pressure, force, optimum die length, and the influence of friction and reduction of area were investigated. Theoretical and experimental data were compared, and close agreement was observed. Also comparing the previous works with the present method, improvements on upper bound values were observed.