Finite Element and Experimental Analysis of the preheating stage of High Speed Blow Forming (HSBF) process

Abstract

High-Speed Blow Forming (HSBF) is a new manufacturing technology based on superplastic forming for the production of complex shape thin sheet of aluminum alloys for electrical car body panels. A major challenge for the full scale industrialization of the process in automotive industry is to reduce the overall HSBF processing time while keeping temperature distribution as uniform as possible on the dies. In this study, the thermal mapping of the dies during the preheating cycle (also known as offline heating) of a HSBF process was investigated using a hybrid experimental-numerical method with a view to minimizing the preheating time and to obtain a uniform temperature distribution on the dies surfaces at the end of the preheating cycle. To this end, the upper and lower dies of an industrial size part were instrumented with 14 thermocouples at different locations of the dies. The process was simulated using the finite element software ABAQUS to predict the temperature evolution over the entire surfaces of the dies from room temperature to the target temperature. The predictions were validated by comparison with the experimental measurements. Based on the obtained results a new offline heating cycle insuring minimum discrepancy in temperature distribution and minimum processing time is proposed.