Effect of friction force anisotropy on earing behavior during circular deep-drawing of hardened sheet of 3104 aluminum alloy

A hardened sheet of 3104 aluminum alloy is used for the beverage can body stock. In this material, controlling the ear of the circular deep-drawn cup is important to prevent can forming defects. Previous studies have shown that the friction force between the sheet material and the forming die affects the earing behavior during circular deep-drawing, in addition to the plastic anisotropy of the material. However, the effect of the anisotropy of the friction coefficient remains unclear. In this study, I investigated the effect of friction force anisotropy on earing behavior of the hardened sheet of 3104 alloy by circular deep-drawing test. This results that the ear profile changes by friction coefficient anisotropy. Moreover, I calculated the ear profile using the elementary method of analysis (or slab method). This analysis leads to the following conclusions: (1) The angle to rolling direction of ear is determined by plastic anisotropy, i.e., in-plane anisotropy of Lankford value, work hardening exponent and plastic strength coefficient. However, the relative height relation of ears and valleys in a cup cannot be explained by only the parameters. (2) Regarding the balance of cup ear and valley, the friction coefficient anisotropy affects. These determine the final ear profile.