Forming Behavior in Cylindrical Deep Drawing Considering Material Anisotropy and Die Shoulder Radius

In this paper, we present the forming behavior in cylindrical deep drawing, focusing on the die shoulder R shape. In the deep drawing process, material anisotropy causes irregularities, known as “ears,” on the cup rim, which can reduce the yield rate. Conventionally, ear formation suppression requires material development. In this study, a “multiple-R die” was developed, in which the die shoulder R shape was varied in the circumferential direction in cylindrical deep drawing, and forming behavior was investigated through experiments. Experimental results show that the multiple-R die can reduce the ear height if the material anisotropy, die shoulder R shape, and material and die position are properly set. In the multiple-R die, ear height was reduced, and the thickness deviation was almost the same as that of the conventional die, although the cylindricity was high. The reason for the suppressed ear height is that the peak material flows to the side of the circumferentially larger die shoulder.