Defects' characteristics of Al-alloy thin-walled tube NC bending under small bending radii

By using FE simulation and experiments, the characteristics of various defects of thin-walled Al-alloy tube in NC bending under small bending radii (relative bending radii 1.5D and 1.25D, relative bending radius is bending radius/outer diameter) are investigated, in which two bending specifications of 5052O Al-alloy tube including φ50 × 1 mm(outer diameter × wall thickness) and φ75 × 1.5 mm are focused. The results show that: The wrinkling is the most frequent defect in NC bending under small bending radii; Besides the cracking on bending regions, the over thinning induced fracture easily occur on front bending fields and rear bending fields during NC bending of Al-alloy tubes; With reasonable processing parameters, the cross section distortion of Al-alloy tube in NC bending under small bending radii is far less than 5%.