Direct Electric Current Spot Treatment’s Effect on Springback of 90 Degree Bent 2024-T3 Aluminum

Abstract

One of the largest issues for sheet metal forming techniques such as stamping and incremental forming is springback. Springback is the elastic recovery of a material after it has been formed resulting in distorted part geometries. Springback can be compensated for during the forming process, however, this often requires forming the metal further than the desired shape. Unfortunately, if a formed part is designed such that it is close to its forming limit, compensation could push the material too far and cause fracture. It has been shown that by pulsing electric current throughout an entire workpiece during forming, springback can be greatly reduced and sometimes eliminated. This paper examines the effect of pulsing direct electric current, through localized points of a workpiece after it has been deformed into a 90-degree bend, but prior to the reversal of the bending die (i.e., while the part is still constrained). It was found that, with a high current density for a short amount of time, springback could be greatly reduced without the need to run a larger current through the entire workpiece. The largest springback reduction was seen when the electric current was forced to flow across the bend in the specimen. This finding is advantageous for industry as it will allow springback reduction in large parts that would normally require much larger power sources to generate the correct current density, if current is run through the entire part. A potential barrier between industry and this technology is that machines would need to be either created or modified to apply electric current at known places at a specific current density and time. To modify an existing machine may be difficult because the machine would need to be insulated from the electric current.