| 摘要 |
PURPOSE:To compensate the sensitivity fluctuation of the flaw detection signal by the roughness of a flaw detecting surface by receiving the reflected echo from a wedge bottom surface, and controlling an AGC circuit by the signal obtained by prescribed operations. CONSTITUTION:The ultrasonic beam 9 from an oscillator 1 for transmission and reception is reflected by the bottom surface of a metallic wedge 2 as an echo 10 which is made incident into a material 5 to bemeasured via a contact medium 7. Part of the echo 10 is converted to voltage by an oscillator 3 for correction affixed on the front surface of the wedge, and this voltage is supplied to an arithmetic circuit 14 by way of a receiving part 13. The arithmetic expression is beforehand set in the circuit 14 by determining the coeffts. of the segments showing sensitivity changes by using a number of test pieces having the same reflection source as that for a sensitivity standard test piece and differing only in the roughness of the flaw detecting surface. The circuit 14 makes operation based on the echo signal from the circuit 13 and controls an AGC circuit 15 by the output thereof, thereby compensating sensitivity automatically. Hence, the signal from a transmission and reception part 12 having the surface roughness of the material 5 is compensated and is fed to a monitor 16. |
