The upper-bound analysis of cold extrusion process for box-shaped products

The kinematically admissible velocity fields were determined by the two kinds of metal flow models, and then the general formulae for calculating the punch pressures in back extrusion of various kinds of box-shaped products (such as rectangle, square, regular, polygon, ellipse or circle) were derived through the computation of total power compute and the optimization of height of deformed zone. The value results for the technological design of extrusion process were obtained by the analysis of upper-bound solution. The research shows that the upper-bound solutions calculated by presented in this paper velocity fields are very close to the experimental values.