DEFORMATION OF HIGH PURITY COPPER SPECIMENS IN COMPRESSION BETWEEN FLAT AND GROOVED DIES

摘要

Experiments were carried out to generate data on cold compression of high purity copper specimens having different height-to-diameter (Ho/Do) ratios (0.5 to 1.5) between two flat dies having various degrees of surface condition (knurled, dry and lubricated) and between grooved dies having different groove numbers (1 to 3). Different Ho/Do ratios , die surface conditions and number of grooved resulted in different loading characteristics and also different modes of deformation. The latter case resulted forward and backward extrusion modes plus the radial flow resulting from ordinary compression. Three shapes of deformed specimen were obtained according to the number of grooves. Load values decreased as Ho/Do increased and friction condition improved. For a fixed load, displacement increased for higher Ho/Do ratio. For a fixed displacement, however, load level decreased as Ho/Do increased. Surface strains were apparently affected by the above variables. In case of compression between grooved dies, in spite of the different mode of deformation, the same trends were obtained.