Eddy current sensor for detecting metal gap and defect under high-temperature and narrow-slit condition

Abstract

The invention relates to an eddy current sensor used under a high-temperature and narrow-slit condition, which belongs to the field of detection technology. The method comprises the following steps of: (1) manufacturing a micro scale planar coil 1 by using ultraviolet-lithography and galvanoplasty (UV-LIGA) technology; (2) manufacturing a nickel-iron alloy iron core 3 by a galvanoplasty manufacturing process; and (3) providing a two-layer eddy current sensor structure formed by laminating the micro planar coil and a magnetic core. The sensor has the advantages of simple structure, flexible application and capability of detecting a gap and a defect of a metal material under the narrow-slit and high-temperature condition.

Description

technical field [0001] The eddy current sensor of the invention belongs to the technical field of detection. Background technique [0002] The eddy current sensor is a detection device that uses the principle of eddy current and uses metal materials as the detection object to detect parameters such as metal gaps, defects, and vibration frequencies. The device has the characteristics of high detection accuracy, simple and easy-to-use components, and does not damage the function and surface quality of the detection object. It has important application value in aviation, instrumentation, machinery manufacturing and other industries. [0003] The traditional eddy current sensor generally uses the excitation signal to pass through the single-layer coil to generate an alternating magnetic field to change the impedance of the coil. When the impedance is a single-valued function of the distance between the coil and the metal measurement target, the displacement can be Convert it in...

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Problems solved by technology

When a single-layer coil is used, due to the high reluctance, in order to achieve a certain self-inductance, the required number of coil turns is large, the thickness is large, and the coil distributed capacitance is large, requiring a high input signal frequency, which is susceptible to interference

[0004] For commonly used eddy current sensors, the coil is generally wound into a spiral shape with enameled wire. Due to the large diameter and many turns of the copper wire, the diameter and thickness of the sensor probe exceed 6-10 mm. For some special cases, such as narrow Under the condition of seam (less than 5 mm) and high temperature (above 300°C), it is difficult to reach the detection position due to the large size of the probe; in addition, the failure of the copper wire insulation layer at high temperature causes electrical conduction and coil oxidation, which distorts the measurement results and even Can't measure

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