Deep drawing of cylindrical cups with friction-actuated blank holding

Abstract The draw force and the blank-holder variations that are obtained when drawing with friction-actuated blank holding are determined theoretically for a urethane pad of particular dimensions. A prototype tooling for blanking and drawing of sheet metal of thickness 1 mm and less to cups of diameter 100 mm at draw ratio of 1.85 with such a blank holder has been designed, fabricated and tested. Experimental results from the above tooling are presented, these including the punch and blank-holder force variations with stroke and the thickness strains in the cup wall. The experimentally-measured punch force variations are compared with the theoretical predictions. The theoretical and the experimentally-measured blank-holding force variations are presented, together with the variation of critical blank-holding force that is needed to suppress wrinkling. The differences between the theoretical and the experimental force variations are discussed.