METHOD FOR MEASURING MATERIAL OF COLD ROLLED STEEL SHEET AND MEASURING INSTRUMENT OF SPEED OF ULTRASONIC WAVE PROPAGATED IN COLD ROLLED STEEL PLATE

摘要

PURPOSE:To utilize an electromagnetic ultrasonic wave method with eliminates the need for an acoustic coupling medium by making two acoustic speed measuring instruments for SHO plate ultrasonic waves cross each other in the middle of an electromagnetic ultrasonic probe for detection and arranging an electromagnetic ultrasonic probe for a standing wave there. CONSTITUTION:The required press moldability of the cold rolled steel sheet used for the body of an automobile or the outer package of a home electric product is measured. For the purpose, the ratios K1 and K2 of the speeds of a transversal ultrasonic wave which is propagated inside in the thickness direction while vibrating in parallel and at right angles to a rolling direction and the speed of a longitudinal ultrasonic wave which is propagated in the thickness direction and the ratio K3 of the speed of an SHO plate wave ultrasonic wave which is propagated at 45 deg. to the rolling direction and the speed of an SHO plate wave ultrasonic wave which is propagated in parallel or at right angles to the rolling direction are measured. Then the two acoustic speed measuring instrument consisting of electromagnetic ultrasonic probes T1 and T2 for SHO plate wave generation and 1st and 2nd electromagnetic ultrasonic probes R1 and R'1, and R2 and R'2 for SHO plate wave detection are held and crossed at 45 deg. and the electromagnetic ultrasonic probe 50 for the standing wave is arranged at the intersection to measure the ratios K1 - K3 at the same time.