Lehrstuhl für Fertigungstechnologie, Universität Erlangen-Nürnberg

Adaptive Stretch Bending of Aluminum Extrusions

Datum: 22.12.1998



  • Prof. Dr.-Ing. Dr.h.c. M. Geiger
  • Prof. Dr.-Ing. H. Hoffmann, München

The application of the space-frame concept in big series car body manufacturing is hindered by big variations of the extrusions’ geometrical and mechanical properties, which result in a low reproducibility at conventional bending processes. The objective of the work presented has been the development of an adaptive stretch bending process allowing a single-step bending process without any subsequent straightening processes. With the adaptive stretch bending process the tool reaction force is recorded versus the traveled distance of the extrusions’ clampings during the initial bending phase. From this information an optimal value for the axial tension as controlled variable can be derived. The relationship between the measured data and the springback behavior of the extrusion is represented by an artificial neural network. This network additionally allows a continuous improvement of the performance of the process control in big series applications. Examinations as for different cross sections and bending radii showed that the control strategy can be transferred to nearly any bending task.