New Approach for Closed Loop Control of Deep Drawing Process for a Control Intervention during Deep Drawing Stroke

Abstract

The production of irregularly shaped deep drawing parts with high quality requirements, which are common in today’s automotive body shell production, consistently challenge production processes. This challenge results from the high design requirements and automotive lightweight design, and hence the necessary use of high strength steels. Metal forming technology deals with these challenges using highly sophisticated methods to control the material flow. Several control loop methods have existed already in order to control the material flow in deep drawing processes, but only methods with a control intervention between two strokes. However, this kind of control method merely allows control intervention on measurements on the previous part or on measurements of material properties before the actual process. The method developed at the Institute for Metal Forming Technology in Stuttgart makes a control intervention possible during the deep drawing stroke. The used reference variable is the part wall stress and the control variable is the blankholder force, which is manipulated by using the segment elastic blankholder as an actuator. In this paper the experimental setup, the control methods, and the control loop itself will be presented. Furthermore, the developments of the new method will be described.