PROBE FOR DETECTING FLAW OF HOT WORKED MATERIAL BY USING EDDY CURRENT

摘要

PURPOSE:To make the S/N ratio of a detect signal higher, by sealing between a space in a case and shielding plate so that the pressure of a cooling water passed through the space is not applied to the shielding plate. CONSTITUTION:When flaw detection is made, cooling water is passed from an inlet port 3 to an outlet port 4 through a space 2 as shown by arrows and, at the same time, a probe A is opposed to a material 11 to be examined with an interval D in-between. Moreover, an exciting signal is supplied to the coil 9 of the main body 7 of the probe A and a magnetic flux produced by the coil 9 gives its effect to the material 11 to be examined through a shielding plate 6. Under this condition, the probe A and the material 11 to be examined are relatively moved in the horizontal direction. When a flaw exists on the surface of the material 11 to be examined in the course of the horizontal movement, an eddy electric current produced by the magnetic flux changes at the place of the flaw and the change is caught by the detecting coil 9, and then, a flaw signal is outputted from the coil 9.