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A new tool design concept for deep drawing is presented. The design features a hydraulic shimming system providing a variable blank holder force (BHF). An objective function describing the geometric quality of the drawn part and the process stability is formulated. The objective function is used in a gradient based optimization scheme to find a set of optimal loads for the drawing of a square bar sink. It is shown that a variable BHF can increase the process robustness to changes in process parameters compared to a constant BHF.

This paper presents results from application of discrete state spacebased feedback control of the blank holder force (BHF) magnitude and distribution in the drawing ofa rectangular workpiece. By means of monitoring the flange draw-in during the punch stroke, the controller makes continuousadjustments to the BHF magnitude and distribution by individuallycontrolling the pressure of a hydraulic fluid in a number of cavitiesembedded in the blank holder plate. The adjustments are conducted onlineduring the punch stroke to minimize the deviation of the achieved flange draw-in from a predetermined reference.

This paper demonstrates the use of an intelligent shimming system to compensate for changes in process output due to tool wear. A new tool concept with integrated hydraulic cavities used as actuators in feedback control system is presented. By prescribing a hydraulic pressure in the individual cavities the blank-holder force distribution can be controlled during the punch stroke.By means of a sequence of numerical simulations abrasive wear is imposed to the deep drawing of a rectangular cup. The abrasive wear is modelled by changing the tool surface geometry using an algorithm based on the sliding energy density.As the tool surfaces are changed the material draw-in is significantly altered when using conventional open-loop control of the blank-holder force. A feed-back controller is presented which is capable of reducing the draw-in difference to a certain degree. Further a learning algorithm is introduced to the system, which is able to improve the response of the feed-back system significantly.