Contact-induced vibration tool in incremental sheet forming for formability improvement of aluminum sheets

Formability improvement is extremely crucial in incremental sheet forming (ISF) of low-ductility material and high wall angle 3-dimensional parts. The contact-induced vibration from the tool rotation provides an alternative route for optimizing formability; however, the underlying mechanism induced by the contact-induced vibration effect has not yet been fully elucidated. This study designed a contact-induced vibration tool (V-Tool) with a flat elliptical shape tip and applied it into the ISF of a 0.5 mm Al5052 sheet. Hyperbola shapes were manufactured by the ISF with V-Tool and conventional tool (C-Tool) with different rotation speeds to experimentally investigate the forming limit, temperature, hardness, fracture morphology, and material deformation. The main results show that the vibration effect and the resultant shear deformation by V-Tool result in the lower friction heat verified by the peak temperature from 180 degrees C to 80 degrees C and higher formability from the thinning rate of 54%-84% as compared to those of the conventional tool (C-Tool). Further, the deformation observation with the drilled holes on initial sheets indicates that the contact-induced vibration effect in the ISF with V-Tool may produce more shear deformation on the inner surface to delay the continuous enlargement of the drilled hole along the meridional direction. (C) 2022 The Authors. Published by Elsevier B.V.