| 摘要 |
PURPOSE:To make the whole body more compact and prevent various noises from entering through the film covering a long cord from outside, by uniting a coil bobbin and an amplifier. CONSTITUTION:The coil bobbin 1 is composed of a single body or a plurality of components such as a bobbin cap 8 and the like. Concave line grooves 11 are formed on the periphery of the coil bobbin 1. Thereinside, a detecting coil 7 is wound, and the end thereof is inserted into the bobbin 1. A hollow chamber 2 is formed inside the bobbin 1, at a given position, for housing an amplifier 3. Moreover, insertion grooves 6 are formed to be fitted with the board 4 of the amplifier 3. The crack- detecting coil bobbin 1 to be inserted through a nonmagnetic metal narrow tube is moved with a long cord connected to the rear part. The output from the detecting coil 7 is amplified by means of the amplifier 3 and sent to a crack- detecting apparatus and a recorder through the cord connected to the bobbin 1 in order to detect the degree of corrosion damage in the tube. |
