Analysis of the asymmetric upsetting test with extremely high strain rate as tool for friction measurement

摘要

The upsetting of flat plates offers a way to analyse friction conditions in the interface areabetween tool and workpiece with regard to surface microstructure, lubrication, and materialproperties. If a plate is compressed between two punches and the friction conditions at bothinterfaces are different, the billet bends over at both sides of the punches. The final angle is a measurefor the friction difference. In traditional friction tests the forming speed is too low or the specimen isdeformed only at the surface. In most metal forming processes, e.g. rolling, friction conditions cannotbe described precisely because of the unknown behaviour of the lubricant at high pressure or highdeformation speed. The advantages of the test proposed here are simplicity, full deformation, andfeasibility with high speed. The process is cost effective and does not require large scale equipment.