| 摘要 |
PURPOSE:To enable the separation and identification of the flaw signal from the noise signal due to changes in the distance between a probe coil and the surface of material to be inspected while allowing the detection of flaws in the valley portion of an oscillation mark by energizing a probe coil with two currents different in the frequency. CONSTITUTION:Outputs with frequencies f1 and f2 of oscillators 2 and 3 are applied to a bridge 5 through a frequency mixer 4 for mixing them. The impedances of probe coils 5a and 5b varies with the surface condition of a cast piece 1 and any unbalanced current of the bridge 5 due to this is sent to filters 6 and 7 which separates it into the signal f1' of the component based on the frequency f1 and the signal f2' of the component based on the frequency f2. The signals f1' and f2' thus separated are sent to detectors 10 and 11 via amplifiers 8 and 9. These signals are inputted separately into phase rotators 12 and 13. Then, the signal of the frequency f1 appears on an x1, y1 vector plane while the signal of the frequency f2 does on an x2, y2 vector plane as necessary or unnecessary signal. |
