Fuzzy adaptive control of circular-cup deep-drawing process using variable blank holder force technique

摘要

A new fuzzy BHF adaptive control method was developed to improve the reliability and flexibility of the circular-cup deep-drawing process. The new fuzzy method adds a new constraint function to the former fuzzy model which is constructed by two evaluation functions. The constraint function, which is given as a gradient of the drawing stress, dσ/d△DR, obtained from the punch load-flange reduction ratio curve, is introduced for determining the progress of deep-drawing. A multifunction computer-controlled deep-drawing simulator with above fuzzy controller was used for experiments. The materials tested were aluminum alloy, cold rolling steel and brass sheets. Using the new fuzzy method, all experimental results showed that the lifting-up and wrinkle behaviors at the flange part of the blank were suppressed. Furthermore, we evaluated the wall thickness distribution using the thickness difference between the end site and punch shoulder of a drawn cup. As a result, the maximum and minimum wall thicknesses in the case of new fuzzy model were got better than ones in the case of the former model. It was confirmed that the new fuzzy BHF adaptive control method improved the reliability and flexibility of the process for various materials and blank sizes.