Springback Compensation by Superposition of Stress in Air Bending

Abstract

In the sheet metal processing industry bending is one of the common metal forming processes. Depending on the process state, a differentiation has to be made between free bending (air bending) in the die and coining (die bending). Because of its flexibility the air bending process is nowadays one of the widely applied processes for sheet metal bending, but the springback phenomenon is still a great challenge for the industrial application. At the Institute of Forming Technology and Lightweight Construction (IUL) of the Technische Universität Dortmund, Germany, a new method has been developed allowing the compensation of springback effects in air bending of sheet metals. This method is based on the incremental and local superposition of stresses in the forming zone. The superposition occurs after the bending operation but before unloading along the sheet metal width. The advantage of this new method is that a minimal force is required to compensate the springback. This paper describes the springback compensation method in detail and presents first experimental results.