| 摘要 |
The invention relates to a method and means for measuring the depth of cracks, using a potential probe connected to a measuring instrument and having two current terminals and additional voltage-measuring terminals (potential probe method). The object of the invention is to eliminate the separate calibration devices needed for the checks and collective measurements necessary when using known potential probes, and to make the check measurements in conjunction with the actual depth-measuring process. This problem is solvable by using a potential probe (S) as per the drawing, where at least two pairs of terminals (1+2, 3+4) having known but different spacings serve as adjustment measuring portions and are connected to an adjustment circuit (JM, UM) in a measuring-instrument microcomputer (M) and an additional pair of terminals (2, 3) having a known spacing serve as a crack-depth measuring portion and are connected to a crack-depth measuring circuit (TM) in the microcomputer. The probe is attached to the workpiece so that the adjustment portions lie on opposite sides of the crack, whereas the crack-depth measuring portion contains the crack.
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