UPPER-BOUND ANALYSIS OF SQUARE-DIE FORWARD EXTRUSION

The present study is the preliminary research for the derivation of th e generalized velocity field in three-dimensional square-die forward e xtrusion. As a fundamental model, the square-die forward extrusion of circular-shaped bars from regular polygonal billets is chosen and a si mple kinematically-admissible velocity field is proposed. From the pro posed velocity field, the upper-bound extrusion load, the velocity dis tribution and the average length of the extruded billets are determine d by minimizing the total power consumption with respect to chosen par ameters. Experiments have been carried out with hard-solder billets at room temperature. The theoretical predictions of the extrusion load a re in good agreement with the experimental results and there is also a reasonable agreement in the average extruded length between theory an d experiment.