Formability analysis of incrementally hole-flanged parts using different tool sizes

Abstract

This contribution analyses the formability of incrementally hole flanged parts using different tool radii (10, 20 and 47.9 mm). The smallest radius (10 mm) can induce full incremental benefits in the hole-flanged specimen, whereas the biggest one generates a formability behaviour closer to a conventional press forming. In the first case, the necking process is clearly delayed, being the development of a fracture in the middle of the wall flange the mechanism that controls the failure of the specimen. In contrast, in the second case, failure is governed by the appearance and development of a neck at the edge of the flange, which ends in material fracture. The intermediate tool radius (20 mm) shows midway features between a conventional and a fully incrementally formed specimen. The location and fracture mode of the flanged parts with different tool sizes are experimentally analysed and discussed within the Forming Limit Diagram (FLD) using the optical strain measurement system ARGUS®.