Experimental Study and Efficient Prediction on Forming Forces in Incremental Sheet Forming

Incremental sheet forming (ISF) is a promising forming process in which complex 3D shapes are formed from a sheet of metal using a simple moving tool. The efficient prediction of contact forces in ISF is desirable to monitor the forming process, prevent failure, and implement on-line control and process optimization. However, traditional Finite Element (FE) simulation used for force prediction is significantly time-consuming for complex products. The purpose of this study is to investigate the ISF force prediction and characteristics under different forming conditions and build a potential efficient model. In the present work, forces during the cone forming process with different wall angles and step down sizes were recorded and compared. Different force trends were identified and discussed with reference to bending and strain hardening mechanics. Influences of different parameters on designated formability were also qualified which should benefit the product design process. An efficient predictive model based on upper-bound approach was applied for force prediction in this case. Predicted tangential forces were then compared with the experimental results showing relatively good agreement. The limits of the proposed model were also identified and the potential of future improvements were suggested.