| 摘要 |
PURPOSE:To measure the shape and thickness of a body to be detected with high precision regardless of the temperature of the object of measurement by generating an alternating magnetic field near the body to be detected by an exciting coil, and utilizing the intensity of the magnetic field near the exciting coil or the height or phase of the density of leak magnetic flux from the body to be detected. CONSTITUTION:Voltages detected by detection coils 2 and 3 are amplified by amplifiers 5 and 6, whose outputs V1 and V2 are inputted to a gain phase gauge 7, which outputs the gain G1 and phase difference psi1 of the V1 and V2 to a computing element 9. Signals G2 and psi2 relating to the thickness are linearized and processed to output a voltage V01 proportional to the thickness. Further, the G2 and psi2 are processed similarly to output a voltage V02 proportional to the gap between the detection coil 2 and a pipe. Plural detection coils 2 and 3 are arranged circumferentially to measure the position and thickness of the pipe at an installation point, thereby knowing the outward appearance and the shape of the thickness.
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