Recent advances in industrially applied numerically aided springback compensation

Springback is a common and intrinsic phenomenon of every deep drawing operation. For various reasons the application of high strength steels and aluminum in automotive industry is still increasing. Unfortunately, these materials tend to larger springback than mild steels. Therefore it is more difficult to guarantee the accuracy of the part shape without a proper springback compensation. Several countermeasures can be applied to minimize springback, but it is not always possible to reduce springback sufficiently. Additionally, the overbending technique has been developed to counter springback by modification of the tool shape. This method gives satisfactory results for a whole class of parts which are very susceptible to springback. In this paper an improvement, the smooth displacement adjustment (SDA) method, is presented. Basically the shape deviation of the part is calculated and subsequently approximated by an L2-projection of sufficiently smooth global analytical functions. Due to the restriction to analytical functions the computed shape deviations can be easily transferred to the tool surface in order to compensate them. The use of the new method is demonstrated on an industrial part. The paper ends with conclusions and recommendations.