| 摘要 |
PURPOSE:To enable accurate measurement of thickness of a liner unaffected by ambient temperature, by installing deviation calculating means of deviation between a measured value of thickness of a liner of the standard pipe and a measured value of a specimen and calculating means of a measured value of the liner of the specimen pipe. CONSTITUTION:The liner thickness of the standard pipe 31 is measured prior to the measuring operations. Next, in calculation controlling apparatus 100, the specified number of pulses are fed out to a pulse motor driving source 19, a coil holder 9 is pushed forward to the pipe 31 and a measured value Msi theta(i=1-4) changed and corrected based upon signals Ai, alpha1 detected by coils 22... and introduced as outputs is allowed to be stored in a memorizing apparatus 102. Further, in the apparatus 100, when an absolute value DELTAMSi is obtained by subtracting the preliminarily mea sured value Msi from the measured value Msi and the value exceeds an upper limit of the predetermined allowable deviation K, an alarm is issued from an alarm appara tus for renewed correction of sensitivity. And, when the deviation value is less than the absolute value K, the apparatus 100 feeds out the predetermined number of pulses to the electric source 19 for change and correction, based upon the signals Ai, alphai introduced by detection by coils 22......, and thus the measured value Mli(i=1-4) is obtained.
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