| 摘要 |
<p>A version of the instrument for testing materials, e.g. steel sheets, which have a flat surface has two cobalt samarium permanent magnets (1,2) separated by a steel pole piece (3). The outer ends of the magnets are in contact with pole shoes (4,5) which conduct the flux to their lower flat faces. Between the steel pole piece and a coupling piece (10) is a detector (9) which may be a Hall effect device or a coil. The flux is conducted between the pole pieces (4,5) through the nylon tray (11) which holds the assembly toqether, and through the surface of the material under test (7). Another version designed for testing steel rods has several such assemblies arranged radially around a cylindrical sleeve.</p> |
