Hydraulic steel gate defect detection method and detection system

Abstract

The invention discloses a hydraulic steel gate defect detection method and system. The method comprises the steps that 1, an ACFM probe used for detecting defects is arranged along the surface of a hydraulic steel gate; 2, exciting an alternating electromagnetic field on the surface of the hydraulic steel gate through a magnet exciting coil in the probe, enabling the metal surface of the gate to generate skin current, moving the detection probe on the surface of the hydraulic steel gate at a certain scanning speed, detecting a magnetic field distortion signal generated by the induction current on the surface of the steel gate due to defects in real time, and picking up the magnetic field distortion signal through a sensing coil; 3, performing amplification and filtering processing on the magnetic field distortion signal picked up by the detection probe to obtain recognizable signal data; 4, feature extraction is conducted on the processed signal data, specifically, three-dimensional magnetic field component feature signals at the crack are detected, and the three-dimensional magnetic field component feature signals comprise magnetic field feature signals in the length direction and the depth direction of the crack; 5, performing crack feature reconstruction based on the obtained magnetic field distortion signal, constructing a reconstruction equation of crack length and depth by adopting an adaptive fitting algorithm, and calculating to obtain length and depth feature parameters of the crack; and 6, according to the obtained crack length and depth characteristic parameters, the severity of the crack is judged, and the safety condition of the hydraulic steel gate is evaluated. According to the detection method, the structural defects can be efficiently and accurately detected in the service process of the hydraulic steel gate.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic gate detection, and in particular relates to a hydraulic steel gate defect detection method and detection system. Background Art

[0002] Hydraulic steel gates are an important part of water conservancy projects. They serve in complex water environments and climatic conditions for a long time and are easily affected by factors such as corrosion, fatigue, and stress concentration, which lead to defects such as cracks and corrosion pits. Especially under working conditions such as high water pressure and large flow, tiny cracks may expand under the action of cyclic stress, eventually causing structural failure, seriously threatening the safe operation of hydraulic facilities.

[0003] In recent years, many hydraulic steel gate damage accidents caused by material defects, welding quality problems and fatigue damage have shown that existing detection methods have limitations when facing complex service environments and hidden defects, and are unable to meet the high reliability and safety requirements of modern water conservancy projects.

[0004] Currently, non-destructive testing technology has been widely used in the safety assessment of hydraulic steel gates. Among them, AC electromagnetic field detection technology has attracted attention in the field of defect detection of hydraulic steel gates due to its advantages such as high sensitivity to cracks, no need for direct contact, and ability to penetrate coatings and corrosion layers.

[0005] However, traditional manual inspection methods are limited by the complex structure of the gate and the underwater operating environment. Not only is the inspection cost high, but periodic inspections are difficult to fully cover key stress-bearing parts. The reliability of the inspection results can easily be affected by human misjudgment or incomplete inspections, resulting in potential defects not being discovered in a timely manner and increasing the risk of structural failure. Summary of the Invention

[0006] The present invention provides a hydraulic steel gate defect detection method and detection system to solve the problem of low efficiency and accuracy in hydraulic gate structure detection.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: In one aspect, the present application provides a method for detecting defects in hydraulic steel gates, comprising the following steps: S1, ACFM probes are arranged along the surface of hydraulic steel gates for detecting defects; S2. The excitation coil in the probe excites an alternating electromagnetic field on the surface of the hydraulic steel gate, causing skin current to be generated on the metal surface of the gate. The detection probe moves at a certain scanning speed on the surface of the hydraulic steel gate, and detects the magnetic field distortion signal generated by the induced current on the steel gate surface due to defects in real time, and picks it up through the sensor coil; S3, amplifying and filtering the magnetic field distortion signal picked up by the detection probe to obtain identifiable signal data; S4. Extract features from the processed signal data, specifically including detecting the three-dimensional magnetic field component characteristic signals at the crack, including the magnetic field characteristic signals in the crack length direction and depth direction. and ; S5. Reconstruct the crack characteristics based on the acquired magnetic field distortion signal, use an adaptive fitting algorithm to construct a reconstruction equation for the crack length and depth, and calculate the length and depth characteristic parameters of the crack; S6. Determine the severity of the crack based on the obtained crack length and depth characteristic parameters, and evaluate the safety status of the hydraulic steel gate.

[0008] Furthermore, during the detection process, there is a lifting gap between the ACFM probe and the hydraulic steel gate, and the lifting gap H ranges from 2 to 3 mm.

[0009] Furthermore, in step S1, the ACFM probe is a longitudinal array probe, and an array imaging feature method is used to distinguish crack signals from lift-off interference signals, and cracks are effectively identified through the temporal and spatial differences of the response signals.

[0010] Furthermore, in step S1, multiple ACFM probe arrays are arranged in different areas of the surface of the hydraulic steel gate to perform multi-point defect detection simultaneously, and realize synchronous collection and real-time analysis of multi-point detection data.

[0011] Furthermore, in step S3, the weak magnetic field signal collected by the sensor coil is differentially amplified by the front-end differential amplifier circuit, then passes through a bandpass filter circuit to remove noise interference, and then passes through an A / D converter to convert it into a digital signal at a sampling frequency of 10kHz and is saved by a computer data acquisition module.

[0012] Further, in step S5, according to The distance between the peak and the trough determines the crack length. The specific calculation formula is:

[0013] Where x peak 、x trough They are The X-direction coordinate values ​​corresponding to the peaks and troughs of the magnetic field signal.

[0014] Further, in step S5, according to and The empirical model is established based on the amplitude ratio of , and the crack depth D can be expressed as:

[0015] Where, for The maximum amplitude of the magnetic field change, for is the maximum amplitude of the magnetic field change, k and b are empirical coefficients obtained by fitting the experimental data.

[0016] Furthermore, step S5-1 is provided between step S5 and step S6. Step S5-1 compensates for the lift-off effect, specifically comprising: Define the attenuation coefficient α:

[0017] Among them, V H is the detection signal amplitude at the actual lift-off height H, V H0 is the detection signal amplitude at the standard lift-off height; Furthermore, the expression of crack length after lift-off compensation correction is: , the expression of crack depth after lift-off compensation correction is: .

[0018] Furthermore, in step S1, the excitation frequency of the ACFM probe is set in the range of 1 kHz to 5 kHz; and the shell material of the probe is a non-metallic material.

[0019] On the other hand, the present application provides a hydraulic steel gate defect detection system for implementing the above-mentioned hydraulic steel gate defect detection method, comprising: Excitation module, used to generate AC magnetic field to induce electromagnetic induced current on the surface of hydraulic steel gate; Magnetic field sensing module, used to collect magnetic field distortion signals on the surface of hydraulic steel gates in real time; A signal processing module is used to amplify, filter and convert the collected magnetic field distortion signal; Feature analysis module, used to reconstruct crack size features from processed signals; Display module, used to visually present crack detection results in graphical or numerical form; The control module is used to coordinate the work of the excitation module, magnetic field sensing module, and signal processing module to ensure the synchronization and accuracy of the working timing and data communication of each module.

[0020] The present invention can achieve the following beneficial effects: The present invention provides a defect detection method for hydraulic steel gates, enabling nondestructive testing of these gates. This method addresses the issues of existing crack defect detection, which suffer from insufficient accuracy and significant environmental interference. The method includes: exciting an alternating electromagnetic field on the gate surface using an ACFM probe and acquiring magnetic field distortion signals; filtering and feature extraction of the acquired signals; calculating crack length and depth using magnetic field characteristic parameters, and compensating for lift-off effects based on attenuation coefficients to accurately reconstruct defect dimensions. This detection method offers high accuracy and real-time performance, making it suitable for safety assessments of hydraulic steel gates. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 A schematic flow chart of a method for detecting defects in hydraulic steel gates according to the present invention; Figure 2 The magnetic field characteristic diagram of the crack region along the crack length direction formed in step S4 of the present invention; Figure 3 The magnetic field characteristic diagram of the crack region along the depth direction formed in step S4 of the present invention; Figure 4 The final crack region magnetic field characteristic map formed by integration in step S4 of the present invention; Figure 5 The present invention provides a test report generated by the method for detecting defects in hydraulic steel gates. DETAILED DESCRIPTION

[0022] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0023] like Figures 1 to 5 As shown, the present invention provides a method for detecting defects in hydraulic steel gates, which is suitable for detecting surface defects of steel gates made of Q235 low-carbon steel, and specifically includes the following steps: S1. Probe Selection and Arrangement. This method utilizes a dedicated array ACFM probe and employs array imaging features to distinguish crack signals from lift-off interference signals. Cracks are effectively identified through temporal and spatial differences in the response signals. This includes an excitation coil and a sensor coil array. The excitation coil is made of copper wire with a diameter of 0.2 mm and 200 turns. The probe housing is constructed of non-metallic materials, such as acrylic or ceramic, to reduce signal interference. The probe excitation current is set to 800 mA, and the excitation frequency is set between 1 kHz and 5 kHz to ensure moderate excitation electromagnetic field strength and high signal sensitivity. A constant lift-off gap H is maintained between the probe detection surface and the steel gate, ranging from 2 to 3 mm.

[0024] In a preferred embodiment, multiple ACFM probe arrays are arranged in different areas on the surface of the hydraulic steel gate to perform multi-point defect detection simultaneously, and synchronized collection and real-time analysis of multi-point detection data are achieved to improve detection efficiency and accuracy.

[0025] S2. Probe scanning and signal acquisition: A coordinate system (x, y, z) is established on the surface of the hydraulic steel gate, where the x direction is defined as the crack length direction, the z direction is the crack depth direction, and the y direction is perpendicular to the xz plane and the y direction is the scanning direction.

[0026] The ACFM probe moves steadily along the y-axis at a constant speed v, where v is 20 mm / s. Simultaneously, the excitation coil inside the probe generates an alternating magnetic field, which causes skin currents on the surface of the steel gate. When the skin currents pass through crack defects on the gate surface, they generate distorted magnetic field signals around the defects, which are picked up in real time by the sensing coils.

[0027] S3. Signal preprocessing: The weak magnetic field signal collected by the sensor coil is differentially amplified by the front-end differential amplifier circuit, and then passes through a bandpass filter circuit to remove noise interference. The filter frequency is set in the range of 1.5~2.5 kHz; then it passes through an A / D converter and is converted into a digital signal at a sampling frequency of 10kHz, and is stored by the computer data acquisition module.

[0028] S4. Extraction of crack magnetic field characteristics. According to the ACFM detection principle, the magnetic field characteristics at the crack are mainly manifested as the magnetic field in the x direction. and the magnetic field in the z direction The changes are defined as:

[0029] in, and is the magnetic field reference signal when there is no crack, 、 is the change in magnetic field caused by the crack.

[0030] The collected data is processed and the magnetic field characteristic map of the crack area is drawn in the form of a two-dimensional image, which clearly shows the characteristic area and specific location of the crack.

[0031] S5. Extraction of crack size characteristic parameters.

[0032] Determination of crack length L: From The waveform of the magnetic field component shows obvious peak-valley features at both ends of the crack. The distance between the peak and the trough determines the crack length. The specific calculation formula is:

[0033] Where x peak 、x trough They are The X-direction coordinate values ​​corresponding to the peaks and troughs of the magnetic field signal.

[0034] Determination of crack depth D: According to and The empirical model is established based on the amplitude ratio of , and the crack depth can be expressed as:

[0035] Where, is the maximum amplitude of the Bx magnetic field change, for is the maximum amplitude of the magnetic field change, k and b are empirical coefficients obtained by fitting the experimental data.

[0036] S6. Lift-off effect compensation In order to reduce the error caused by the change in the lift-off gap between the probe and the detection surface, the attenuation coefficient α is defined as:

[0037] Among them, V H is the detection signal amplitude when the actual lifting gap H is reached, V H0 is the detection signal amplitude at a standard lift-off gap, typically 2 mm. The attenuation coefficient has no significant correlation with crack length or depth, enabling accurate crack size assessment even when the lift-off gap varies.

[0038] The expressions of crack length and depth after lift-off compensation correction are:

[0039] By using the above lift-off compensation algorithm to correct the magnetic field distortion signal, the influence of the lift-off gap change on the detection result can be effectively eliminated, and the final measurement error can be significantly reduced.

[0040] S7. Safety evaluation and result output.

[0041] The obtained crack length and depth characteristic parameters are compared and analyzed with the safety operation standards for hydraulic steel gates to determine the safety level of the steel gate cracks. The test results are intuitively output in numerical and graphical form, and a test report is automatically generated. The safety operation standards for hydraulic steel gates are based on preset safety thresholds, such as lengths ≥5 mm or depths ≥2 mm, which are considered dangerous.

[0042] If the crack size exceeds a safe threshold, the system issues an alarm and recommends repair or replacement.

[0043] Field verification of this implementation plan in actual engineering projects has shown that the crack length detection accuracy reaches above 95%, and the error is controlled within 5%; the crack depth detection accuracy reaches above 90%, and the error is controlled within 8%.

[0044] This application addresses the characteristics of hydraulic steel gates made of Q235 low-carbon steel and optimizes the probe's magnetic core, coil parameters, and detection frequency to improve the accuracy and stability of defect detection. Therefore, this proposed method for hydraulic steel gate defect detection meets the practical needs of surface crack defect detection and safety assessment for hydraulic steel gates, demonstrating promising engineering application prospects and reliability.

[0045] The present application also provides a hydraulic steel gate defect detection system for implementing the above hydraulic steel gate defect detection method, comprising: Excitation module, used to generate AC magnetic field to induce electromagnetic induced current on the surface of hydraulic steel gate; Magnetic field sensing module, used to collect magnetic field distortion signals on the surface of hydraulic steel gates in real time; A signal processing module is used to amplify, filter and convert the collected magnetic field distortion signal; Feature analysis module, used to reconstruct crack size features from processed signals; Display module, used to visually present crack detection results in graphical or numerical form; The control module is used to coordinate the work of the excitation module, magnetic field sensing module, and signal processing module to ensure the synchronization and accuracy of the working timing and data communication of each module.

[0046] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for detecting defects in hydraulic steel gates, characterized by: The following steps are involved: S1, ACFM probes are arranged along the surface of hydraulic steel gates for detecting defects; S2. The excitation coil in the probe excites an alternating electromagnetic field on the surface of the hydraulic steel gate, causing skin current to be generated on the metal surface of the gate. The detection probe moves at a certain scanning speed on the surface of the hydraulic steel gate, and detects the magnetic field distortion signal generated by the induced current on the steel gate surface due to defects in real time, and picks it up through the sensor coil; S3, amplifying and filtering the magnetic field distortion signal picked up by the detection probe to obtain identifiable signal data; S4. Extract features from the processed signal data, specifically including detecting the three-dimensional magnetic field component characteristic signals at the crack, including the magnetic field characteristic signals in the crack length direction and depth direction. and ; S5. Reconstruct the crack characteristics based on the acquired magnetic field distortion signal, use an adaptive fitting algorithm to construct a reconstruction equation for the crack length and depth, and calculate the length and depth characteristic parameters of the crack; S6. Determine the severity of the crack based on the obtained crack length and depth characteristic parameters, and evaluate the safety status of the hydraulic steel gate.

2. A method for detecting defects in hydraulic steel gates according to claim 1, characterized in that: During the detection process, there is a lifting gap between the ACFM probe and the hydraulic steel gate, and the lifting gap H ranges from 2 to 3 mm.

3. A method for detecting defects in hydraulic steel gates according to claim 1, characterized in that: In step S1, the ACFM probe is a longitudinal array probe, which uses an array imaging feature method to distinguish crack signals from lift-off interference signals, and effectively identifies cracks through the temporal and spatial differences of the response signals.

4. A method for detecting defects in hydraulic steel gates according to claim 1, characterized in that: In step S1, multiple ACFM probe arrays are arranged in different areas on the surface of the hydraulic steel gate to perform multi-point defect detection simultaneously, and realize synchronous collection and real-time analysis of multi-point detection data.

5. A method for detecting defects in hydraulic steel gates according to claim 1, characterized in that: In step S3, the weak magnetic field signal collected by the sensor coil is differentially amplified by the front-end differential amplifier circuit, then passes through a bandpass filter circuit to remove noise interference, and then passes through an A / D converter to convert it into a digital signal at a sampling frequency of 10kHz and is saved by the computer data acquisition module.

6. A method for detecting defects in hydraulic steel gates according to claim 1, characterized in that: In step S5, according to The distance between the peak and the trough determines the crack length. The specific calculation formula is: Where x peak 、x trough are the X-direction coordinate values ​​corresponding to the peak and trough of the Bz magnetic field signal respectively.

7. A method for detecting defects in hydraulic steel gates according to claim 1, characterized in that: In step S5, according to and The empirical model is established based on the amplitude ratio of , and the crack depth D can be expressed as: Where, for The maximum amplitude of the magnetic field change, for is the maximum amplitude of the magnetic field change, k and b are empirical coefficients obtained by fitting the experimental data.

8. A method for detecting defects in hydraulic steel gates according to claim 1, characterized in that: A step S5-1 is provided between step S5 and step S6. Step S5-1 compensates for the lift-off effect, specifically comprising: Define the attenuation coefficient α: Among them, V H is the detection signal amplitude at the actual lift-off height H, V H0 is the detection signal amplitude at the standard lift-off height; Furthermore, the expression of crack length after lift-off compensation correction is: , the expression of crack depth after lift-off compensation correction is: .

9. A method for detecting defects in hydraulic steel gates according to claim 1, characterized in that: In step S1, the excitation frequency of the ACFM probe is set in the range of 1 kHz to 5 kHz; the shell material of the probe is a non-metallic material.

10. A hydraulic steel gate defect detection system, used to implement the hydraulic steel gate defect detection method according to any one of claims 1 to 9, characterized in that: include: Excitation module, used to generate AC magnetic field to induce electromagnetic induction current on the surface of hydraulic steel gate; Magnetic field sensing module, used to collect magnetic field distortion signals on the surface of hydraulic steel gates in real time; A signal processing module is used to amplify, filter and convert the collected magnetic field distortion signal; Feature analysis module, used to reconstruct crack size features from processed signals; Display module, used to visually present crack detection results in graphical or numerical form; The control module is used to coordinate the work of the excitation module, magnetic field sensing module, and signal processing module to ensure the synchronization and accuracy of the working timing and data communication of each module.

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