Application of pulsation in deep drawing and press hardening processes
Anwendung von Pulsation beim Tiefziehen und Presshärten
The main reason for using mechanical servo presses is to improve productivity. The angular velocity of the drive shaft is adjusted between two points out of workpiece contact, i.e. bottom dead center and tool touch point which is 330° of crank angle. For example, the impact shock can be reduced with soft touch. The following paper shows numerical and experimental results of new deep drawing technologies with low-frequency pulsation of ram and cushion. The pulsation is superimposed during workpiece contact between tool touch point and bottom dead center. For materials with less hardening e.g. mild steel or some aluminum alloys the Cushion-Ram-Pulsation (CRP) is used to increase the drawing depth. The CRP process leads to a lower drawing force while opening the flange during the pulsation. Other kinematics called Bi-Directional Deep Drawing (BDD) induces work hardening at the beginning of the deep drawing process. Thus the strengthened area can resist higher drawing forces. The BDD process is suitable for materials with large hardening e.g. high strength or austenitic steels.