Ear height control by die radius shape in cylindrical deep drawing

This study presents the relationship between die radius shape and anisotropy that suppresses ear height in cylindrical deep drawing. In deep drawing, the cup is formed with irregularities on the edge, called “earing”, due to the anisotropy of sheet material. In previous studies, suppression of ear height has mainly been conducted by suppression of anisotropy through material development. The authors have previously confirmed that ear height can be suppressed in cylindrical deep drawing using “Multiple R die” in which the die shoulder R shape varies in the circumferential direction. However, the detailed relationship between the die radius shape in Multiple R die and material anisotropy has not been clarified. Therefore, in this study, the effect of the die radius shape in Multiple R die on the formed shape was investigated by experiment and finite element analysis. The larger the difference in the R dimension of the die shoulder, the larger the change in the earing shape. In addition, it was confirmed that the ear height can be suppressed by changing the die shoulder R shape according to the anisotropy distribution.