An enhanced displacement adjustment method: Springback and thinning compensation

Abstract In the paper, we present an enhanced numerical method for the forming tool design optimisation in sheet metal forming. The applied procedures enable a determination of appropriate forming tool geometry so that manufacture of a formed product with specified geometry would be ensured. Apart from springback occurred by the formed part after removal of the forming tools also impact of thinning of the sheet metal during the forming process is considered in the method, and both effects are correspondingly compensated in an iterative procedure of the forming tool geometry determination. The enhanced displacement adjustment method (E-DA) is based on the well-known displacement adjustment (DA) method the application of which is indeed relatively simple, but has proved also, due to an increased number of iterations needed to achieve the required tolerance and possible loss of accuracy, to be less successful when forming of parts with more complex geometry is considered. Computational efficiency in the E-DA method is achieved by applying additional point topology mappings, which establish corresponding interrelations between the discretised point topologies used in the definition of the prescribed product geometry, current tool geometry and on this basis actually computed product geometry, contributing thus significantly in improving the accuracy of communicated data. The advantage of the improved method over the conventional DA method is demonstrated by considering the forming tool design optimisation in channel bending and forming of cylindrically symmetric products.