Accurate localization technique for stamping sheet metal parts with complex surfaces

Sheet metal stamping processes involving three-dimensional parts have been appealing various engineering research efforts, especially when it comes to high strength steels. Particularly, for those with complex, sculptured surfaces, the springback phenomena causes non-trivial geometry problems in both evaluation and compensation of geometric distortions. Computer simulations based on Finite Element (FE) improve and enhance stamping methods in order to achieve required dimensional tolerances and reduce time-consuming design and production stages. FE results are compared with the desired product geometry for validation of the simulation accuracy, as well as indicating design status with respect to part geometry. In these assessments, part geometric localization at design space is a very critical step that design engineers must pay great attention in positioning both tool and part surfaces. In this study, a new surface localization methodology is presented for comparison of FE analysis results with non-contacted scanned part surfaces. In this methodology, the gap projection and centroid superposing technique are used for localizing the complex surfaces in a design space and applied to the process design steps of a roof stiffener automotive part. An assessment of shape distortion indicators shows that the proposed methodology can localize the surfaces accurately and much efficiently than conventional methods.