Friction-actuated blank holding in deep drawing

Abstract

A new method of blank holding in deep drawing has been introduced by the first author. In this method, a urethane pad between two parts of a drawing punch, when compressed by the drawing force applies lateral pressure on the tubular part of a blank holder. As the punch moves to draw the blank, friction between the urethane pad and the blank holder automatically applies the blank holding force. An experimental rig with this type of blank holding was constructed and aluminium, copper and brass cups were drawn. Tests were also conducted with constant-force blank holding for comparison. Results indicate lower punch force, modest increases in limiting draw ratios and less thickness variations when compared with cups formed under constant-force blank holding.