| 摘要 |
PROBLEM TO BE SOLVED: To measure an iron loss evaluation value on-line and continuously with the use of ultrasonic plate-wave mode, by frequency-modulating a part of ultrasonic transmission signal from a transmission element and then detecting the modulation part corresponding to reception signal. SOLUTION: Ultrasonic transmission element T and reception element R scan an oriented electromagnetic steel plate S in the direction of its width at a specified speed by movement of the steel plate S. A part of transmission signal for making the transmission element T transmit ultrasonics is frequencymodulated. Meanwhile, the signal from the reception element R is amplified with a pre-amplifier 13 and an amplifier 14, and. the modulated part corresponding to what was frequencymodulated is detected by a modulation point identification circuit 15. A propagation time measurement circuit 16 obtains the reception time of modulated part detected by the modulation point identification circuit 15, and based on that, the propagation time of ultrasonics is obtained. An iron loss value calculation circuit 17 converts the propagation into an iron loss value according to a predetermined calculation expression and outputs it. Thus, accurate propagation time is detected while eliminating the affect from noise, for improved measurement. |
