Abstract
Using three kinds of round bar work metals 5 mm in diameter, cylindrical cup-forming was examined in the tribo-extrusion proposed in the first report and the backward extrusion. The punch pressure pm in the tribo-extrusion of the aluminium and the copper was about 30% lower than that in the backward extrusion. The pm in the tribo-extrusion of low carbon steel was about 2.1∼2.35 GPa within the range of reduction of area of 70∼97%, while it was impossible to finish the cup owing to the danger of punch failure by the backward extrusion. The relative punch pressure pm/Y in the tribo-extrusion of copper and low carbon steel ranged from 2.5 to 4, and these values were approximately consistent with those predicted theoretically. The cup surface was finished without galling, and the surface roughness Rmax was about 0.5∼1.8 μm, regardless of the dry frictional condition. The cup wall thickness also was produced with a relatively high accuracy.
