Process Robustness in Sheet Metal Forming by an Integrated Engineering Strategy

In the modern automotive industry the development of car bodies depends considerably on the use of computer-aided tools. Herewith one can meet the challenges of rising product complexity and growing number of variants.

About fifteen years ago simulation of sheet metal forming was used for the first time in industrial application. However, the calculation times were long and the quality of the results was often unsatisfactory. Today, enabled by improved material models and new numerical methods, those simulations have become essential for the evaluation of press-tools before they are manufactured.

Due to the high number of varying influences on the production process of sheet metals, the resulting quality of the parts is not always stable. In most cases, these variances are lying in predefined limits of tolerance. Otherwise additional efforts and costs for testing the parts and for reworking them are required leading to higher reject costs in total.

By the means of existing highly qualitative methods for numerical simulation combined with standardized statistical methods one can identify these varying influences, their interconnection and effects on car body parts. On the basis of such an analysis appropriate optimization algorithms will lead to an improved overall part quality along with higher robustness.

In this paper, the realization of an integrated engineering strategy as mentioned above within the forming department of the BMW Group, the combination of corresponding engineering tools, and their reasonable cooperation in a planning process will be described. The essential steps of these processes and the methods and tools used are presented illustrated by industrial-sized examples.