An investigation of multi-pass incremental sheet forming

Abstract

This study investigates toolpath strategies of multi-pass incremental sheet forming (MSPIF) including a combination of an IN (I) pass where the tool moves inwards and downwards and an OUT (O) pass where the tool moves outward and upward. MSPIF processes (III, IIO, IOI and IOO) were investigated to form cone and dome shapes using experimental testing and finite element (FE) simulation. It was found that any IN pass after the initial IN pass, produced stepped features due to Rigid Body Translation (RBT) of the formed part, with the magnitude of the step being dependent on the both the quantity and position of the IN passes. The IOO strategy was more effective in producing a flat bottom cup (no stepped features), but due to the succession of OUT passes used, sheet thinning occurred near the centre of the formed part. A 4-stage IOOO strategy successfully increased the final maximum draw angle by 23% relative to the maximum wall angle of a single pass. The results have shown that the MSPIF approach can be used as an effective means to improve the formability in incremental sheet forming.