| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device for detecting surely a micro surface defect in a nonmagnetic metal tube such as a copper tube for cold and hot water supply and a copper tube with an inner face groove for a heat exchanger, a copper alloy tube, and an aluminum alloy tube, under the condition where the metal tube runs along a production line such as extraction drawing and winding. SOLUTION: In this method for detecting continuously the surface defect in the running nonmagnetic metal tube, an eddy current is generated in the metal tube, and a magnetic field generated by impeding a flow of the eddy current with the surface defect of the metal tube is measured by a SQUID sensor to detect the surface defect. COPYRIGHT: (C)2006,JPO&NCIPI
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