| 摘要 |
PROBLEM TO BE SOLVED: To enable an iron loss value of a steel plate to be calculated and evaluated by receiving a plate wave ultrasonic wave by plural receivers with their different distances with transmitters and obtaining a sound speed with high precision from a distance between delay time between the receivers obtained from the receive signal and a distance between the receivers. SOLUTION: An ultrasonic pulser 11 pulse-drives a transmitter T according to a transmission trigger signal of a system controller 10 and sends a plate wave ultrasonic wave. An A/D converter 13 samples receive signals of the receivers R1 and R2 with a send trigger signal being a reference thereof and performs mutual correlative calculation using these. A system controller 10 calculates a sound speed of the plate wave ultrasonic wave with high precision when the maximum value of the mutual correlative calculation value is a transmission delay time. The system controller 10 obtains an iron loss value of an electromagnetic steel plate from the sound speed based on the relationship between the sound speed obtained in advance and the iron loss value of the electromagnetic steel plate. Thus, wave change having measurement dynamic range and including noise hardly affects it, and online continuous measurement is made possible. |
