Non-destructive electromagnetic tester for ferromagnetic object - provides magnetisation pulses to test object and measures logarithm of normal components of residual magnetic field gradient

摘要

A current pulse generator (1) is coupled to two magnetising coils (2) connected to produce magnetising pulses in opposition. The material (3) under test is displaced inside the coils and magnetically sensitive Hall detectors (4) sense the induced magnetisation. The detector outputs are connected to peak detectors (5) and convertors (6) with a logarithmic law. The converter outputs are connected to a totaliser (7) with an antilogarithmic converter (8) at its output. This output is then recorded (9) for inspection. During magnetisation, the magnitude of the pulses is chosen to bring saturation to the object to be controlled in the magnetisation zone.