Enhancement of process capabilities in electrically-assisted double sided incremental forming

摘要

Electrically-assisted incremental sheet forming (E-ISF) is an effective method to improve formability by introducing the electric current in ISF process. This method is particularly useful for production of lightweight 'hard-to-form' materials such as magnesium and titanium alloys. However, the use of electricity and heat may also lead to side effects to formed components, such as unacceptable surface finish. In this work, an improved E-DSIF process has been developed by combining the electrically-assisted forming technology, the double sided incremental forming (DSIF) and a newly designed slave tool force control device to ensure stable tool-sheet contact. Different types of forming tools and toolpath strategies are explored to improve surface finish and geometrical accuracy by using a customized DSIF machine. AZ31B magnesium alloy sheets are formed into a truncated cone shape to verify the proposed E-DSIF process. In the investigation, the causes of rough surface finish are investigated in detail, and the surface finish is refined by improving the contact condition at tool-sheet interface. In addition, a hybrid toolpath strategy is proposed to further enhance the geometrical accuracy. The results demonstrate that the two challenging issues, surface finish and geometrical accuracy, could be improved by using the enhanced technologies of E-DSIF.