| 摘要 |
In a device for measuring the wall thickness of pipes by means of an ultrasonic probe, the ultrasonic waves generated by the probe are temporally compared with the reflected waves. For this purpose, the probe has a magnet which premagnetises the pipe wall in the axial direction, as well as a transmitting and receiving coil which generates a magnetic field which is superimposed on the premagnetising field. In order to be able to measure the wall thickness of an annular section of the pipe, the magnet consists of a ring magnet which surrounds the tube and generates a magnetic flux in the axial direction beyond the entire circumference of the pipe. The coil consists of a ring coil surrounding the pipe, and the reflected waves are evaluated in terms of width and/or amplitude.
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