| 摘要 |
PURPOSE:To detect defects in any direction with single scanning, by arranging a plurality of magnetic poles each having a coil zigzag on a base block to run 3-phase alternating currents between three adjacent magnetic pole coils so that a uniform rotary magnetic field id generated. CONSTITUTION:A magnetizer 11 on material 10 to be detected has a plurality of magnetic poles 13A-13F provided zigzag alternatly along the length and coild 14A-14F wound on the respective magnetic poles 13A-13F on a base block 12 and both width- wise sides thereof. As 3-phase alternating current flows through the coils 14A-14F, a rotary magnetic field 15 is generated in a range surrounded by the three adjacent magnetic poles 13A-13F. Therefore, a flaw detecting surface of the material 10 being inspected can be magnetized by the rotary magnetic field 15 by scanning the magnetizer 11 in the direction orthogonal to the length of base block 12 sequentially, keeping the gap between the magnetic poles 13A-13F and the material 10 being measured. Thus, defects can be detected in any direction over the range of magnetization. In addition, scanning roughly orthogonal to the array direction eliminates undesired overlapping of rotary magnetid fields or others to enable efficinet flaw detection. This also permits a highly reliable flaw detection with a uniform sensitivity. |
