Evaluation of Wrinkling States Using In-Process Ultrasonic Examination during Sheet Metal Forming

In press forming, sampling inspection has been performed during production. However, in sampling inspection, there is the possibility that defective products will proceed to the next process despite inspection. In this paper, we investigated a method for detecting wrinkle defects occurring during deep drawing in order to prevent the outflow of defective products. Deep-drawing tests were performed using a drawing die incorporating an ultrasonic transducer. During deep drawing, ultrasonic waves were irradiated to the interface between the die and the workpiece, and the occurrence of wrinkles was examined on the basis of ultrasonic reflection characteristics. The ultrasonic reflection intensity was changed by the occurrence of the wrinkles. The influence of wrinkle height and wrinkle wavelength on relative reflection intensity was shown. It was demonstrated that ultrasonic measurement is an effective method of detecting wrinkles during press forming.