Development of Apparatus for Evaluation of Wrinkles in Sheet Metal Forming Using Angle Beam Technique

Abstract

Ultrasonic measurement is used to evaluate wrinkles during sheet metal forming. The authors developed a new apparatus for investigating the relationship between the wrinkles in press forming and the ultrasonic reflection characteristic of an angle beam. The new evaluation apparatus was composed of probe-fixing parts, an upper die, a middle die, and a lower die. A specimen was sandwiched by a pair of dies in the evaluation apparatus. Angle beam probes for transmission and reception were set on the upper die. Specimens in the form of plates having periodic trapezoidal wrinkles were fabricated by electro-discharge machining. In the new evaluation apparatus, the specimen is placed in contact with the die. Wrinkling was found to change the ultrasonic reflection characteristic of an angle beam. The new apparatus can thus be used to evaluate wrinkles using the angle beam technique.