Adaptive control of blank holder force in sheet metal forming: modelling and experimental validation

Sheet metal forming is a key process in manufacturing, but it often suffers from defects such as wrinkling, tearing, and springback. These issues not only reduce the quality of the final parts but also increase material waste and production costs. A critical parameter in avoiding such defects is the blank holder force (BHF), which controls the material flow during forming. Conventional systems, such as hydraulic cushions or mechanical springs, generally provide constant force and lack the flexibility needed to adapt to changing conditions during the process. This thesis explores a new approach to adaptive control of the BHF by employing a ferrofluidic actuator. Unlike traditional systems, the actuator allows for variable and precisely controlled forces to be applied in real time. To investigate its effectiveness, a U-shape deep drawing process was selected as a case study. Experimental trials were carried out under different force conditions and compared with numerical simulations performed in LS-DYNA. The results show that variable BHF significantly improves thickness distribution and reduces springback compared to constant-force setups. The study demonstrates the potential of ferrofluidic actuators for creating more flexible, efficient, and defect-resistant forming systems, paving the way for smarter and more sustainable manufacturing solutions.