Advancing Elevated Temperature Hydro/Pneumatic Sheet Metal Forming Operations Through Reverse Bulging

摘要

In spite of the numerous advantages of hydro/pneumatic (H/P) forming operations over the conventional mechanical ones, there are many drawbacks that hamper their progress on a large scale. Non-uniform thickness distribution of the formed part, and the potentially severe thinning associated with large plastic strains, represent major setbacks. Imposing a pre-thinning reverse bulging step has been shown to ease the problem with specific part geometries and materials. In this effort we explore the great merits of this approach on enhancing the formability of an emerging lightweight material: the AZ31B-H24 magnesium alloy. Moreover, the approach is taken to another level, where a simple monitoring technique for providing a direct feedback on the sheet's advancement during the process, is utilised to further control and optimise the process. The results demonstrate enormous time-savings that can be achieved with the proper use of reverse bulging, for both simple and complex part geometries.