Observations of barrelling in aluminium solid cylinders during cold upsetting using different lubricants

Abstract

This work deals with experimental derivation of friction factor values m for different lubricants and their combinations using ring compression tests and standard ring geometry 6:3:2. The values thus obtained were used to generate data on cold upsetting of annealed aluminium solid cylinders. Two aspect ratios and three strain levels were considered for the upsetting experiment. Calculations were made with the assumption that the curvature of the bulge followed a circular arc. The measured radius of curvature of the bulge was shown to agree with the value calculated using experimental data. Relationships were established between various bulge parameters such as new hoop strain, hydrostatic stress, geometrical shape factor, and stress ratio factor, and the friction factor m of different lubricants.