Abstract
A method of using ultrasonic waves for measuring the contact condition between a workpiece and die during stamping has been developed. Ultrasonic waves are reflected by air, so the condition of contact between a workpiece and a die can be examined by measuring the height of ultrasonic waves. We measured time traces of the conditions of contact between the workpiece and the die during actual stamping using a servo press. The experimental results show that we can measure the time traces of the gap between the workpiece and the die using ultrasonic waves. Next, we examined how workpiece thickness and material affect the reflection and transmission characteristics of ultrasonic waves. The height ratio of ultrasonic waves is affected by the sound pressure reflectance, which is defined by the sound impedances of the die and workpiece. Furthermore, the height ratio of ultrasonic waves is also affected by workpiece thickness. Accordingly, the condition of contact between the workpiece and the die during stamping can be measured using ultrasonic waves.
