Low-frequency leakage flux based internal flaw detection circuit for ferro magnetic material

Abstract

The invention discloses a low-frequency leakage flux based internal flaw detection circuit for a ferro magnetic material, and belongs to the field of electromagnetic application and nondestructive testing. The low-frequency leakage flux based internal flaw detection circuit is characterized by consisting of a front amplifying circuit, a servo circuit, a power amplifying circuit, a magnetizing circuit, a signal acquiring circuit, a signal processing circuit and a power supply circuit, wherein the front amplifying circuit adopts a JRC5534 chip as a signal amplifier; the servo circuit adopts an OP07 servo chip; the power amplifying circuit adopts an LM3886 power amplifying chip; the magnetizing circuit adopts zinc ferrite manganese oxide and an enameled wire; the signal acquiring circuit adopts SS94A1 as a hall effect sensor and adopts a TLC2252 as a signal amplifier; the signal processing circuit adopts an STM32F103RCT6 single chip microcomputer; and the power supply circuit adopts LM317and LM337 chips as an AC / DC voltage-reducing module. A collected magnetic field signal on the surface of the ferro magnetic material is compared with an exciting signal, and a defect position of a tested part can be preliminarily detected through a phase difference of two signals.

Description

technical field [0001] The invention relates to an internal flaw detection circuit of a ferromagnetic material based on low-frequency magnetic flux leakage, which belongs to the technical fields of electromagnetic application and nondestructive testing. Background technique [0002] As an important technology for nondestructive testing of ferromagnetic materials, magnetic flux leakage testing has been widely used because of its high detection sensitivity to internal damage of ferromagnetic materials, preliminary quantification, fast detection speed, simple operation, and easy automation. Applications. After the ferromagnetic material is magnetized, defects on the surface or near the surface of the test piece will cause the leakage field of the test piece, so the defect can be found by detecting the change of the leakage field. This technology is widely used in special equipment detection, natural gas pipeline detection and other fields. [0003] However, due to the relativ...

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Problems solved by technology

[0003] However, due to the relatively high excitation frequency used in the existing magnetic flux leakage detection, the penetration depth is greatly limited due to the influence of the skin effect.

Moreover, the existing detection circuits that match the low-frequency magnetic flux leakage technology are relatively complex and costly, resulting in an increase in on-site detection costs

[0004] The invention is an internal flaw detection circuit of ferromagnetic material based on low-frequency magnetic flux leakage, which can effectively improve the shortcomings of low penetration depth, complicated circuit and high cost

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