Metal defect eddy current detection device and probe thereof

Abstract

The invention discloses a frequency mixing technology-based metal defect eddy current detection device and a probe structure thereof. According to the device, the conventional eddy current technology and low-frequency far field eddy current technology are combined, so that one-time complete detection on metal material defects in a wider range can be realized. According to the device, a high-frequency excitation signal and a low-frequency excitation signal are applied to the probe; the conventional eddy current detection mode is adopted by the high-frequency signal; and the far field eddy current detection mode is adopted by the low-frequency signal. The probe is of a differential structure and consists of two groups of coils; and the two groups of coils are symmetrically arranged in a mirror image manner. Each group of coils consists of a large coil and a small coil of which the axes are away from each other for a certain distance; and the two coils are placed according to a far field principle. A low-frequency sinusoidal signal is conducted through the large coil in the probe; a high-frequency sinusoidal signal is conducted through the small coil; and the small coil is used as a detection coil to receive the high-frequency signal and the low-frequency signal. According to the device, defect information of an upper surface and a lower surface of a plate-shaped metal material or an inner wall and an outer wall of a tubular metal material can be simultaneously and accurately acquired in a large range.

Description

technical field [0001] The invention relates to frequency mixing technology, a metal material defect non-destructive testing device and a related probe structure. Background technique [0002] The defect detection of metal materials is of great significance in the field of military industry? According to the principle of electromagnetic induction, the coil carrying alternating current will induce eddy current in the metal material close to it, and the induced eddy current will in turn affect the original magnetic field distribution around the detection coil. As a result, the measured impedance of the detection coil changes. The eddy current carries information such as the thickness, defect, and conductivity of the metal material. By measuring the change in coil impedance caused by the eddy current, the relevant physical parameters of the metal material, such as whether there is a defect, can be inferred. [0003] The traditional eddy current detection device has great adva...

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Problems solved by technology

[0003] The traditional eddy current inspection device has great advantages in the detection of metal material defects due to its simple equipment, convenient use and no pollution, but is limited by the skin effect of eddy current , generally only suitable for the measurement of the surface and near surface of metal materials; the far-field eddy current used for the detection of metal pipes has no skin effect limitation, and can detect defects on the inner and outer walls of the pipe with the same sensitivity, but it is difficult to accurately determine the location of the defects

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