METHOD AND DEVICE FOR MEASURING TUBE THICKNESS DEVIATION AND METHOD AND DEVICE FOR SPECIFYING CAUSE OF OCCURRENCE OF TUBE THICKNESS DEVIATION

摘要

PROBLEM TO BE SOLVED: To provide a method and a device capable of measuring deviations in the thickness of tubes immediately after rolling as they remain hot by an inexpensive and simple system. SOLUTION: A body to be inspected 4 is irradiated with pulse light from a pulse laser to cause abrasion in the surfaces of the body to be inspected 4 to generate ultrasonic waves. The generated ultrasonic waves reciprocally propagate in the inner surfaces and outer surfaces of the body to be inspected 4. An ultrasonic signal detected by a cooling-type electromagnetic ultrasonic sensor 2 is transmitted to a wide-band amplifier 5 and a band-pass filter 6 and converted from analogue into digital form at an A/C converter part 7. The time interval Δt between two adjacent peaks is computed from an A-scope by a well-known technology, and the wall thickness is computed from a sound velocity V in the body to be inspected 4 and the time interval Δt at a thickness computing part 9.