| 摘要 |
PURPOSE:To detect a flaw with high accuracy and at a high speed by once irrespective of the quality of a defect by constituting so as to be rotatable in one body a magnetic field generator and a magnetic field detector which are placed opposingly and symmertrically to the center of a cylindrical body to be inspected, which is carried in the longitudinal direction. CONSTITUTION:A rotary drum 34 in a fixed drum 31 is rotated through a pulley 37 and a timing belt 38 by driving a motor 36. When a steel pipe 1' is carried in, its tip abuts on a tapered part of the tip of the rear part of each sensor holder 47, 40 and is pushed up, and the tip of each sensor holder 47, 40 abuts on the outside circumferential surface of the steel pipe 1' through a push spring 48. A magnetic pole 21a provided to be symmetrical to the center on the rotary drum 34, and a magnetic detector contained in the sensor holders 47, 40 move on the outside circumferential surface of the steel pipe 1' by the rotation of the rotary drum and a parallel advance of the steel pipe 1', and execute a flaw detection of a flaw on the surface. Accordingly, a flaw is detected with a high accuracy and at a high speed by once irrespective of a quality of a defect.
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