The Effect of Cut-out Hole Size on the Formability of Hole Flanging by Multistage Incremental Forming

ABSTRACT:Single point incremental forming is advancing to replace the conventional sheet forming processes. Multi stage incremental forming is introduced to cover some shortcomings of this process and extend the complexity of the shapes that cannot be produced in single stage incremental forming. This method does not require any special equipment and is very economic. In this study the effect of varying cut-out hole size on the formability of hole flanging in multi-stage incremental forming and on the thickness distribution of flange is investigated. The AA1060 aluminum is taken as the experimental material, and the formability is measured as the flange depth without sheet fracture. The flanges are made in 4 stages of 45°, 60°, 75° and 90° at room temperature. Furthermore, the stress and strain patterns are studied utilizing ABAQUS software in order to understand the process mechanics. The results have shown that the hole size has great effect on the flange depth and wall thickness of the part made by multistage incremental forming. The achieved depth decreases with increasing the hole size due to lack of material and thinning is less as the hole diameter gets larger. The FEA results shows that increasing hole diameter will lead to lower stress and hoop strain levels due to decreasing the amount of material under load of the tool. Also it showed that a small amount of work hardening is useful for increasing the formability of the process. Keyword: Multi stage incremental forming, formability, FEA ABAQUS, failure, hole flanging, hole diameter, stress level, strain level. …………………………………………………………………………………………………………………………