Fuzzy Adaptive Control of Blank Holder Force in Circular- Cup Deep-Drawing (Adaptability to Frictional Change and Simple Evaluation of Lubrication)

The flexibility in frictional change of the fuzzy adaptive BHF (blank holder force) control system for the circular-cup deep-drawing has been studied by using the blank with partially applied lubricant. The coefficient of friction between blank material and tool was evaluated from the experimental results of aluminum alloy sheet according to the formulation based on the plasticity deformation model. The lubrication types of the blank tested were fluorine coating, acetone degreasing and a combination of them. The friction coefficient formulation was derived through taking into account the die contact angle, the lifting-up behavior at the flange and the thinning of the wall thickness. The calculated results of the coefficient of friction agree well with the empirical results under the variable BHF condition as well as under the constant BHF condition. The results of the fuzzy adaptive BHF control show that the BHF is adaptively controlled corresponding to the variation in friction. It is proved that fuzzy adaptive BHF control system achieves high reliability and adaptivity of the process for any frictional conditions.