Patent ID: 8289016
Filing Date: 2012-10-16
Classification: G01N

Abstract:
1. A method of eddy-current flaw detection in which an exciting device and a receiving device are disposed in the vicinity of a conductor, which is a subject of the flaw detection, and an eddy current is generated in the conductor by a primary magnetic field generated by the exciting device to generate a secondary magnetic field, the state of the magnetic field is detected by the receiving device to detect the flaw based on a detection signal of the receiving device, wherein the exciting device includes an excitation coil and an iron core, the excitation coil having a first current line and a second current line in which an electric current flows in opposite directions, the iron core being gate-shaped in cross section and having a first leg portion, a second leg portion, and a beam portion connecting the two leg portions, an opening of the iron core on a side opposite to the beam portion facing the conductor, the first current line being disposed on an inner side of the first leg portion and the second leg portion of the iron core, and the second current line being disposed on an outer side of the first leg portion of the iron core, a magnetic circuit is formed around the first current line on the inner side of the iron core and passes through the first leg portion, the beam portion, and the second leg portion of the iron core, and the conductor, and a magnetic circuit is formed around the second current line on the outer side of the iron core and passes through the first leg portion and the beam portion of the iron core, and the receiving device is disposed in a corner between the second leg portion of the iron core and the conductor, on a side opposite to the second current line on the outer side of the iron core.