Determination of the limiting drawing coefficient in the deep drawing of conical cups

The limit deformation of conical cup drawing can be expressed by the limiting drawing coefficient [m] (=[Dd/D0]), where m is the drawing coefficient of conical cups, Dd the die diameter, and D0 the initial blank diameter, [m] the reciprocal of the limiting drawing ratio. Based on the internal relation between conical cups and cylindrical cups, the practical calculation equation of [m] is derived by mechanical analysis, and the forming limit curves expressed by [m] and the limiting drawing coefficient in the first drawing are given. The limiting drawing coefficient given in this paper is proven experimentally to be accurate and convenient.