Viscous pressure forming (VPF) of corrugated thin-walled sheet part with small radius

Viscous pressure forming (VPF) is a new technology of manufacturing complicated shaped parts of difficult-to-form sheet metal alloy. In this paper, the effects of matched forming pressure and blank holder force (BHF) on VPF the corrugated thin-walled sheet parts with small radius (r=2.3mm) for superalloy and stainless steel are investigated. The experimental results show that the load relationship between viscous medium pressure and BHF is the key influence factor on dimensional accuracy, thickness strain distribution, and sealing during forming process. The optimal load relationship curves between viscous medium pressure and BHF were obtained for superalloy and stainless steel under that load condition parts can be formed with smaller thickness reduction and good accuracy surface, any deviation from optimal load relationship would lead to fatal problems to parts and forming process such as flange wrinkling, fracture, inaccuracy of dimensions and larger wall-thickness reduction and viscous medium leaking etc. The rate of sheet blank drawn into die affects the dimensional accuracy and wall-thickness reduction of the position of small radius, and curves between the radius limit r of the formable corrugated surface and the rate of sheet blank drawn in die cavity for superalloy and stainless steel were also obtained by experiments.