| 摘要 |
In detecting a flaw by generating an eddy current in a conductor, it is enabled to easily detect a flaw in the vicinity of a back surface of the conductor. An exciting device and a receiving device are held in the vicinity of a conductor, and an eddy current is generated in the conductor by a primary magnetic field generated by excitation, thereby generating a secondary magnetic field, the state of the magnetic field is detected by the receiving device. The exciting device includes a coil and an iron core. The coil (1) has a first current line and a second current line in which an electric current flows in opposite directions. The iron core (6) is gate-shaped in cross section and includes a first leg portion, a second leg portion, and a beam portion. The iron core (6) is oriented such that an opening thereof on a side opposite to the beam portion faces the conductor (2). The first current line of the coil is disposed on an inner side of the two leg portions of the iron core. The second current line is disposed on an outer side of the first leg portion. Around the first current line is formed a magnetic circuit that passes through the first leg portion, the beam portion, the second leg portion, and the conductor. Around the second current line is formed a magnetic circuit that passes through the first leg portion and the beam portion. The receiving device (7) is disposed in a corner between the second leg portion and the conductor, on a side opposite to the second current line on the outer side of the iron core. |
