Sheet bulging experiment with a viscous pressure-carrying medium

Usually, flexible die forming technology and conventional stamping technology have their own separate and limited application range, as well as their own particular shortcomings. So a more advanced forming method is needed to meet the requirements of increasing component complexity. Viscous pressure forming (VPF), which uses a semi-solid viscous material as the pressure-carrying medium, is suitable for forming parts requiring large sheet deformation using a sequential forming method. In this paper, a sheet metal bulging experiment with three kinds of pressure-carrying media, viscous medium, polyurethane and steel, was studied. The results show that the specimens formed with VPF, compared with those formed with polyurethane and steel, have less wall-thinning and consequently a more uniform wall thickness distribution, and the shape of part is closer to the desired hemisphere. When bulged with back-pressure, the formability of sheet metal can be improved significantly. Thus VPF is a promising sheet metal forming method.