Influences on the part quality in conventional deep drawing processes

Trends in the automotive industry tend towards safety, fuel saving and reduction of exhaust gas result in an increased application of high strength steels as well as stainless steels in the car body production. Deep drawing is a ension/compression forming process of a sheet metal blank to a hollow part without a volitional thickness changing. This permanent deformation occurs when the applied stress exceeds the elastic limit of the material. The elastic deformation within the overall amount of deformation is not desired and leads to the so called spring back, which is directly related to the materials strength, sheet thickness and Young's modulus. Besides strength and elastic modulus there are more factors affecting the part quality or the spring back behavior of deep drawn components. This paper will cover the effect of relevant forming parameters, as there are the die radius, the height of the beads and the drawing clearance. Furthermore, the residual stresses, which are correlated with spring back, were measured by means of the 3MA sensor (Micromagnetic Multiparameter Microstructure- and Stress-Analyses).