Magnetic flux leakage testing method and device based on defect magnetic flux leakage region reversed field

Abstract

The invention discloses a magnetic flux leakage testing method and device based on a defect magnetic flux leakage region reversed field. The method comprises the following steps: (1) magnetizing a magnetic conduction member to be detected; (2) rejecting an existing background magnetic field at the periphery of the magnetized magnetic conduction member to form a magnetic vacuum region; and (3) distributing a magnetic sensitive element on the magnetic vacuum region and picking up a defect leakage magnetic field without a magnetic compression effect and converting into a voltage signal, wherein if the voltage signal has a sudden change, the magnetic conduction member to be detected has a fault; otherwise, no defects exist. According to the device, the magnetic conduction member to be detected is partially magnetized by adopting a penetrating type coil so as to stimulate the leakage magnetic field with the defect on the magnetic conduction member in the magnetized region; permanent magnet pairs are distributed in an inner cavity to generate a reversed magnetic field which is overlapped with a previous background magnetic field to be cancelled out to form the magnetic vacuum region, so that the leakage magnetic field with the defect is leaked and dispersed; meanwhile, magnetic noises caused by the background magnetic field and a magnetic saturation out-of-work phenomenon of an internally-arranged Hall element are eliminated.

Description

technical field [0001] The invention relates to a magnetic flux leakage non-destructive detection technology, in particular to a magnetic flux leakage detection method based on the reverse field of a defect magnetic leakage domain. Background technique [0002] Magnetic flux leakage nondestructive testing technology is widely used in the detection of internal and external defects of ferromagnetic materials. The working principle of magnetic flux leakage detection is: the huge difference in permeability between the magnetized ferromagnet and the air medium at the defect makes the magnetic induction field in the ferromagnet refracted into the air to form a leakage magnetic field, which is picked up by the magnetic sensor and converted into a voltage The signal is used as the record judgment basis for the existence of the defect. The magnitude of the defect leakage field directly affects the voltage signal amplitude characterization and detection observability of the magnetic ...

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