IncreasIng the deep drawabIlIty of al-1050 alumInum sheet usIng multI-poInt blank holder

The deep drawing is a process for shaping flat sheets into cup-shaped articles without failure or excessive localized thinning. The design and control of a deep drawing process depends not only on the material, but also on the condition of the tool material interface, the mechanics of plastic deformation, the equipment used, and the control of metal flow. The equipment and tooling parameters that affect the success or failure of a deep drawing operation are the punch, die radii, die clearance, the press speed, the lubrication, the type of restraint to metal flow such as blank holding force (bhf) [1], blank holder gap (bhG), and draw bead. All of these three types of restraints create restraining force by friction between the strip and the tooling. In this work, the effect of multi-point blank holder on the LdR of Al-1050 sheets was investigated using (bhG) defined as the fixed distance between the blank holder and the die surface in the stamping process by weili et al. [2] to promote the deep drawability of aluminum sheets. Aluminum alloys have been widely used in the fields of automobile and aerospace industries. Due to their bad cold-formability in deep drawing, a lot of forming methods have been implemented to increase the drawing height and the limiting drawing rate (LDR). The conventional deep drawing process is limited to a certain limit drawing ratio beyond which failure will ensue. The purpose of this experimental study is to examine the possibilities of increasing this limitation using the multi-point blank holder. The results from the experiments showed that the multi-point blank holder is effective way to promote deep drawability of Al-1050 sheet.