High Speed Impact Extrusion of Metals

Abstract

The paper describes an investigation of high speed or ‘high energy-rate’ extrusion of cold metal billets. Preliminary trials were carried out with a small pilot machine which, with low explosive drive, could supply up to 430 ft lb per blow at a striking velocity of 132 ft/s. Main trials were subsequently completed using two ‘full-scale’ machines, one explosively driven and the other driven by compressed air, designed to be complementary to each other in such a way that a wide range of energies and striking velocities could be achieved, up to 10 000 ft lb and over 300 ft/s. The metals used were aluminium, copper and mild steel, all in the annealed state. In the main the experience gained was satisfactory and encouraging, and while it was concluded that impact velocities of the order of 50–100 ft/s are feasible, it appeared that the disadvantages of much higher velocities would outweigh the advantages.