A method and device for demagnetizing a ferromagnetic elongated member

Abstract

The invention discloses a method and a device for demagnetizing a ferromagnetic elongated member. According to the method, a permanent magnet is utilized to carry out a reciprocating motion in a quasi demagnetization region of the member along the member; the magnetic pole direction of the permanent magnet is reversely arranged during each reciprocating motion; lift-off from the permanent magnet and the surface of the member is increased; and the permanent magnet is in repeated reciprocating motions until the lift-off to the member is large enough, so that the remanence attenuation in the member is zero to finish demagnetization of the member. The demagnetizing device comprises a magnet assembly, a motion assembly and a lift-off assembly, wherein the magnet assembly is used for generating a magnetic field for demagnetization; the motion assembly is used for achieving the reciprocating motion of the magnet assembly; and the lift-off assembly is used for adjusting the lift-off of the magnet assembly relative to the elongated member. According to the method and the device, a complicated feeding device is not needed; and the device is convenient to operate, simple in structure and good in demagnetization effect, can be applied to demagnetization of remanent fields of ferromagnetic structures of steel bars, wire ropes, cables and the like.

Description

technical field [0001] The invention belongs to the field of electromagnetic non-destructive testing of ferromagnetic components, and more specifically relates to a demagnetization method and device for ferromagnetic slender components. Background technique [0002] Magnetic nondestructive testing is widely used in the detection of cracks, corrosion and stress of ferromagnetic components. During magnetic testing, the component needs to be magnetized, and residual magnetism will inevitably exist in the component after the test is completed; residual magnetism may affect the next test result, affect the working accuracy of the instrument, and may also cause magnetic deflection during electric welding. Therefore, it is very necessary to demagnetize the ferromagnetic member after magnetic detection, especially the ferromagnetic elongated member. [0003] At present, the commonly used demagnetization methods of ferromagnetic components mainly include heating demagnetization, AC ...

AI Technical Summary

Problems solved by technology

Among them, heating demagnetization is to heat the magnet member above the Curie temperature of the member, and then place it in an environment without an external magnetic field to cool slowly, so that the magnetic domains in the member can re-orientate and distribute freely to demagnetize the member. In practice, for steel It is difficult to heat slender ferromagnetic components such as rods and wire ropes, and there are problems such as inconvenient operation for demagnetization by this method; while AC demagnetization, DC demagnetization, and AC-DC composite demagnetization mostly use energized coils to generate demagnetization magnetic fields, which require specific AC and DC power supplies and Commutation circuit, and generally demagnetize the ferromagnetic slender member by passing the ferromagnetic slender member through the coil along the coil axis direction, which requires a corresponding feeding mechanism and supporting devices. The overall structure of the device is complex and inconvenient to operate, and higher cost

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