An Experimental Technique to Determine the Behaviour of Sheet Metal in a Drawbead 2001-01-1136

The behaviour of sheet metal flowing through a drawbead is of significant interest to engineers in the stamping industry. Indeed, the drawbead configuration determines not only the forces that restrain the metal as it flows into the die but also affects how the material workhardens prior to the forming process. The purpose of this work was to experimentally determine in-situ bending radii in a strip while it is pulled through a drawbead. This was achieved by mounting a camera onto the binder of a single-action channel draw die near the end of a drawbead insert. Fiber optic cables were used to direct light in the closed die onto the edge of the sheet. Images of the sheet edge were recorded as it flowed through the drawbead, then post-processed in order to analyze the strip profile and determine the minimum bend radii. Maximum bending strains were also calculated from the measured radii. For each drawbead configuration investigated, experimental observations of bead wrap are presented and discussed.