| 摘要 |
PURPOSE:To enable a rapid and reliable detection of a defective part generated in a ferromagnetic material, by a method wherein a defect detecting probe, in which a magnetic sensor is adhered to one magnetic pole of a magnet, is brought into contact with an object to be inspected. CONSTITUTION:A detecting part is moved in a state that a space between poles, appearing at the end surfaces of ferromagnetic substances 5, 5', which is magnetically closely adhered to a magnet 3, and poles, positioned facing confrontedly to said poles and appearing at a surface of an object 1 to be inspected, is spaced at a given interval by means of a spacer 6, and as a result, a density of magnetic flux at a defective part 2 decreases as compared with that of a nondefective part. The change in density is detected by means of a bridge circuit, in which a magnetic sensor 4 adhered to the interposing substance 5 and a compensating magnetic sensor 4' positioned in a nonmagnetic field state are connected together, to detect the presence of a defective part in the object to be inspected. This permits the reliable and easy detection of the position and size of the defective part in a ferromagnetic material, and besides, permits detection of the defective part in accordance with the shape of the ferromagnetic material. |
