An Investigation of the Direct Extrusion Process with the Application of Oscillatory Energy

Abstract

The plastic working of metals with a superposition of oscillatory energy has be on studied extensively by a large number of investigators. A reduction in the yield stress, and a lowering of the frictional forces between the deforming metal and tools are the main claims of the effects of oscillatory stresses, The objectives of this thesis were: (1) To summarise the historical and technical developments of metal deformation with the application of oscillatory energy, with particular reference to the extrusion and forging processes (2) To undertake research on the use of oscillatory stresses in the extrusion process. The cold extrusion of commercially pure aluminium and pure lead was undertaken through square and curved profile dies, with and without oscillatory energy on a 100 tonf Avery testing machine. Longitudinal force variations having a maximum amplitude of 2 tonf within a frequency range of 20 to 200 c/s, were developed from an electrohydraulic power unit. The extrusion load, punch displacement, force and amplitude of die oscillation were measured with and without oscillatory energy....