| 摘要 |
PURPOSE:To make it possible to inspect the wall thickness of an object to be inspected with high sensitivity, by constituting the titled flaw detecting probe from a permanent magnet for imparting magnetizing force to the part of the object to be inspected pervious to line of magnetic force generated by a detection coil and a probe coil having a magnetizing coil and the detection coil. CONSTITUTION:A detection coil 3, a magnet 4 and a magnetizing coil 7 consitute a probe 1 received in a casing 5. Because the magnetic flux density in a pipe 2 to be inspected can be changed by changing a DC current flowing the magnetizing coil 7 through a lead wire 8, said pipe 2 to be inspected can be held to a magnetized state for always imparting max. sensitivity even if the material quality or the wall thickness of the pipe 2 to be inspected is changed. When an AC current is flowed through the detection coil 3 through a lead wire 6 and a part of line of magnetic force generated from the detection coil 3 permeates through the flaw part of the pipe 2 to be inspected, change is generated in the impedance of the detection coil 3 and, therefore, a flaw can be detected by measuring and comparng the impedances of both coils. |
