Tribological Peculiarity of Galling Position in Square Cup Drawing

Abstract

The high tensile steel sheet attracts attention in recent years. Galling occurs easily in the press forming processes of the high tensile steel sheet because of the high contact pressure. However, the galling behavior can’t be predicted in the forming process yet. The object of this study is to clarify the galling mechanism and develop a prediction method of galling behavior in press forming. Experiments were carried out to investigate the galling behavior in the square cup drawing of a high tensile strength steel sheet. On the die surface, galling occurs at the bottom of the boundary between the straight and corner. On the drawn cup galling starts at the top of the same boundary. The variations of contact pressure, sliding distance and temperature were investigated by using FEM. It was found that galling occurs on the sheet surface position having the history of maximum temperature and at the moment just before sliding out from the die.