| 摘要 |
PURPOSE:To detect a minute defect in the pipe axial direction of a inner surface of a metallic pipe by placing zigzag plural flat detecting coils extending over the whole area in the peripheral direction, on the surface of excitation winding which has been wound to the surface of a cylindrical high permeability magnetic core material. CONSTITUTION:An excitation winding 4 is wound uniformly to a high permeability magnetic core material 1 such as a cylindrical amorphous core, etc., and many flat detecting coils 5 are placed zigzag on its surface so as to cover the whole. Subsequently, it is formed as one body with a holding body 2 of nylon, etc. and a molding material 6, and an eddy current examination insertion type probe for inspecting a pipe surface defect of a metallic pipe is formed. In this state, it is inserted into the pipe, a high frequency current is made to flow to the excitation winding 4, and a defect signal is obtained by detecting and processing a generated eddy current by the detecting coil 5. Accordingly, by selecting correctly a diameter of the detecting coil 5 and its number, a defect in every direction of the pipe surface can be detected with a high accuracy. |
