| 摘要 |
PURPOSE:To provide a flaw detection for a plurality of tubular bodies different in the diameter, by arranging cores wound with detection coils perpendicular to the direction of scanning in such a manner as to be the same in the curvature radius as a pipe body with the intermediate diameter at the center and to be linear or larger in the curvature radius on both sides. CONSTITUTION:Cores 1 are wound with respective driving coils horizontally and respective detection coils 3 vertically. Ten cores 1 are distributed sideways from the center in such a manner as to be perpendicular to the direction of scanning, while they are so arranged in two rows at a proper interval longitudinally in the direction of scanning to position each core 1 longitudinally on the same scanning. Hence, detection coils 3-1-3-10 of the cores 1 are so arrayed to have the bottom of individual coils 3-1-3-10 along the surface of cast iron pipes. The detection coils 3-4-3-7 at the center are arrayed at the curvature radius of phi=400, for instance, in the range of diameter of the cast iron pipe phi=300-600 and those 3-1-3-3 and 3-8-3-10 at both ends linear or at the curvature radium of phi=600.
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