AN INVESTIGATION OF THE VARIATION IN PUNCH & DIE GEOMETRY, BLANK- HOLDING PRESSURE, & DRAWING SPEED IN THE DEEP-DRAWING OF CUPS

The production of a cylindrical cup is the simplest but most important deep-drawing operation on a flat blank of sheet metal. The mechanics of forming are quite complicated and there are many different factors affecting the successful drawing of a blank. In order to further investigate the process of deep-drawing an instrumented tool was designed for operation on a 20 tonne, double acting hydraulic press. This paper investigates the variation and effects of punch and die geometiy, blank-holding pressure, top-ram pressure, lubrication, and drawing speed in the deep-drawing of C.R.l steel cups of 0.9mm thickness. These effects were investigated by drawing a series of cups using D.O.E., where a screening experiment was conducted and the desired factors were varied at different levels. Relatively good results have already been achieved from preliminary work on 1mm mild steel blanks, varying parameters such as (i) punch and die profile radii, (ii) holding pressure and (iii) drawing speed. This paper deals with the experimental work being carried out in order to investigate these effects.