Computer Aided Engineering for a Warm Bulging Test Tooling Design

Warm bulging test is a particular kind of sheet hydroforming. The presence of a warm fluid requires a proper tooling design in order to achieve the benefits related to these particular forming conditions, minimizing blank ruptures and wrinkles presence. The fluid is injected in a properly designed chamber and it produces a sheet bulging deformation. Also the tooling and the sheet are warmed in order to maintain a constant process temperature. In this working conditions, it is necessary to accurately design the tooling layout taking into account: interaction forces, fluid volume, vision system in order to record the deformation conditions and safety systems in order to prevent damage to the workers caused by the warm fluid possible leakage (approximately 200° ÷ 300° C). CAE techniques have a relevant role in order to define proper process parameters such as: sheet thickness, bulging height, fluid pressure. An explicit solver has been used to calculate the forces distribution, developed during the warm sheet bulging, and the needed fluid volume. The obtained values have been used as input data in the structural tooling validation. The authors have designed a warm bulging test layout. The sheet deformation, etched with a grid, is detected through CCD cameras. Diffuse lights, a thermometer and a laser beam adopted to detect the dome height complete the tooling control system.