Non-contact detection device and method for steel pipe body damage based on magnetic flux

Abstract

The present invention discloses a non-contact detection device and method for steel pipe body damage based on magnetic flux. In the device, a power excitation and acquisition module provides power excitation for the detection probe to generate an excitation magnetic field, and collects the magnetic field signal generated by the excitation magnetic field in the steel pipe to be detected; a winding platform is used to wind the excitation coil for the detection probe, the steel pipe is fixed on the test platform, and the detection probe is set on the outside of the steel pipe and can move along the direction of the steel pipe; the detection probe is connected to a signal processing host computer, and the signal processing host computer performs data processing based on the magnetic field signal collected by the detection probe, and analyzes and obtains defect information on the steel pipe. Through the technical solution of the present invention, the problem of detecting steel pipes with thick coating layers is solved while ensuring the accuracy of the detection results, and defects and damage can be discovered and repaired in a timely manner, and rapid winding and rapid detection are achieved. It is easy to assemble and has high detection efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of non-contact detection, and in particular to a non-contact detection device for steel pipe body damage based on magnetic flux and a non-contact detection method for steel pipe body damage based on magnetic flux. Background Art

[0002] Many open-air steel pipelines are covered with a thick coating that provides corrosion protection and thermal insulation. However, as the pipeline ages, it inevitably corrodes, causing surface damage of varying degrees. Due to the presence of the coating, surface damage cannot be directly detected, so non-destructive testing (NDT) is the only way to detect damage. Numerous methods exist for inspecting steel pipes, including magnetic flux leakage testing (MFL), ultrasonic testing, machine vision, and 3D optical testing. MFL offers unique advantages over other methods, while ultrasonic testing requires a coupling agent. Machine vision and 3D optical testing require direct imaging and contact with the pipe surface, making them ineffective for inspecting pipes with MFL.

[0003] Magnetic flux leakage detection technology is based on the high magnetic permeability of steel. Through a certain excitation magnetic field, the magnetic field in the steel pipe can be saturated. When there are no defects in the steel pipe, the magnetic lines of force are strictly confined to the rail pipe wall. However, when there is a missing area on the pipe wall surface, the magnetic lines of force are emitted from the high-permeability steel pipe into the low-permeability air, causing compression and escape of the magnetic lines of force, thereby generating a leakage magnetic field above the defect. Sensors collect and analyze this leakage magnetic field, and the presence of defects can be determined by the characteristics of the waveform. By calculating the amplitude and width of the characteristic signal in the host computer, the size of the defect and the severity of the damage can be graded. However, current magnetic flux leakage detection technology can only be used when the excitation source is close to the steel pipe surface. It cannot detect damage to steel pipes with large lift-off, that is, those with thick coatings. Moreover, most pipe joints are flanged, which makes current magnetic flux leakage detection technology inconvenient to assemble and cannot be quickly disassembled and spliced. Summary of the Invention

[0004] In response to the above problems, the present invention provides a non-contact detection device and method for steel pipeline body damage based on magnetic flux. Through the power excitation and acquisition module and the signal processing host computer, the leakage magnetic signal of the steel pipeline in the excitation magnetic field is collected and processed. Under the premise of ensuring the accuracy of the detection results, the lifting height can reach 30-50mm, which perfectly solves the problem of detecting steel pipes with thicker coating layers. In addition, the defect position and defect size of the steel pipeline can be obtained through signal processing, so that the defect damage can be discovered in time and repaired. Through the combination of the test platform and the winding platform, rapid winding and rapid detection can be achieved, and the assembly is convenient and the detection efficiency is high.

[0005] To achieve the above objectives, the present invention provides a non-contact detection device for steel pipe body damage based on magnetic flux, comprising: a power supply management module, a power excitation and acquisition module, a winding platform, a test platform and a signal processing host computer;

[0006] The power supply management module supplies power to the required modules in the device. The power supply excitation and acquisition module includes a detection probe. The power supply excitation and acquisition module provides DC or AC excitation to the detection probe to generate an excitation magnetic field, and collects the magnetic field signal generated by the excitation magnetic field in the steel pipeline to be detected;

[0007] The winding platform is used to wind the excitation coil for the detection probe. The steel pipeline to be detected is fixed on the test platform. The detection probe wound with the excitation coil is arranged on the outside of the steel pipeline and can move along the direction of the steel pipeline to perform overall magnetic flux detection on the steel pipeline.

[0008] The detection probe is connected to the signal processing host computer, and the signal processing host computer performs data processing based on the magnetic field signal collected by the detection probe, and analyzes and obtains the defect information on the steel pipeline.

[0009] In the above technical solution, preferably, the power excitation and acquisition module also includes a DC power supply, an AC power supply, a power amplifier module, an A / D conversion module and a voltage signal acquisition module. The DC power supply and the AC power supply provide DC and AC excitation modes for the detection probe. The AC power supply is connected to the detection probe through the power amplifier module for power amplification. The detection probe performs analog-to-digital conversion through the A / D conversion module. The voltage signal acquisition module is used to collect the voltage signal of the detection probe.

[0010] In the above technical solution, preferably, the test platform includes a support frame, a ball screw, a slide rail, a slide table, a hand-cranked steering wheel, a steel pipe bracket, a probe fixing bracket and a displacement sensor, the ball screw and the slide rail are fixed in parallel to the support frame, the slide table is respectively sleeved on the ball screw and the slide rail, the hand-cranked steering wheel is fixed to the ball screw and realizes linear translation motion of the slide table under the rotation of the hand-cranked steering wheel;

[0011] The steel pipe to be inspected is fixed on the steel pipe support, and the inspection probe is fixed on the slide via the probe fixing bracket. The inspection area of the inspection probe corresponds to the steel pipe and moves along the steel pipe with the slide, thereby realizing overall monitoring of the steel pipe.

[0012] The displacement sensor is fixed on the slide and is used to monitor the displacement of the detection probe relative to the steel pipeline.

[0013] In the above technical solution, preferably, the signal processing host computer includes a signal reading module, a signal display module, a frequency detection module, an orthogonal demodulation module, a mean filter module, a median filter module, a displacement encoding module, a data alignment module, a defect location module and a defect grading module;

[0014] The signal reading module is used to receive and read the signal collected by the power supply excitation and acquisition module, and the signal display module is used to convert and display the signal received by the signal reading module;

[0015] The frequency detection module is used to calculate the frequency of the signal, and the orthogonal demodulation module performs orthogonal demodulation on the signal according to the frequency of the signal to determine the amplitude and phase change of the signal;

[0016] The mean filter module and the median filter module are used to filter and denoise the signal, and the displacement coding module and the data alignment algorithm are used to encode and position align the filtered and denoised signal to determine the amplitude and width of the signal;

[0017] The defect location module is used to determine the defect location according to the position alignment signal, and the defect classification module is used to classify the defect size according to the amplitude and width of the defect location.

[0018] In the above technical solution, preferably, the wire winding platform includes a stepper motor, a wire winding bracket, a probe skeleton fixed rotor, a DC motor and an enameled wire skeleton, the stepper motor is fixed on the wire winding bracket, the probe skeleton fixed rotor is fixed on the rotor of the stepper motor, and the detection probe is installed on the probe skeleton fixed rotor;

[0019] The DC motor is fixed on the wire winding bracket, and the enameled wire skeleton is fixed on the rotor of the DC motor;

[0020] Driven by the stepping motor and the DC motor, the enameled wire wound on the enameled wire skeleton is wound on the detection probe according to preset excitation coil parameters.

[0021] In the above technical solution, preferably, the coil skeleton of the detection probe is a circular ring structure, and the coil skeleton is a detachable combined structure. During the winding process, the coil skeleton is assembled and sleeved on the probe skeleton fixed rotor. During the magnetic flux detection process, the coil skeleton is assembled and sleeved outside the steel pipe and fixed on the probe fixed bracket, so that the detection probe can move translationally along the steel pipe with the slide.

[0022] In the above technical solution, preferably, the displacement sensor adopts a pull-rope displacement sensor, which includes a sensor base, a grating sensor and a turntable. The turntable is fixed on the sensor base, and the sensor base is fixed relative to the support frame. The pull rope of the turntable moves along the steel pipeline with the detection probe, and the grating sensor detects the expansion and contraction of the pull rope to determine the displacement of the detection probe relative to the steel pipeline.

[0023] The present invention further proposes a non-contact detection method for steel pipe body damage based on magnetic flux, which is applied to the non-contact detection device for steel pipe body damage based on magnetic flux disclosed in any of the above technical solutions, comprising:

[0024] According to the required lift-off distance, excitation coil thickness and excitation coil distance, the detection probe is wound with the excitation coil using the winding platform;

[0025] Fixing the detection probe wound with the excitation coil at a preset position on the test platform, and using a displacement sensor to detect the displacement of the detection probe relative to the steel pipe to be detected;

[0026] driving the detection probe to translate along the steel pipeline while performing magnetic flux detection on the steel pipeline, and synchronously detecting the displacement of the detection probe relative to the steel pipeline;

[0027] The detection signal of the detection probe and the displacement signal of the displacement sensor are collected, and the defect information and the defect position of the steel pipeline are determined according to the detection signal and the displacement signal.

[0028] In the above technical solution, preferably, in the process of using the winding platform to wind the excitation coil on the detection probe, the stepper motor is controlled to drive the probe frame fixed rotor to rotate according to a preset method, and the DC motor is controlled to drive the enameled wire frame to rotate according to a preset method, so that the enameled wire is smoothly wound on the detection probe according to the required lifting distance, excitation coil thickness and the distance between the two excitation coils.

[0029] In the above technical solution, preferably, the specific process of driving the detection probe to translate along the steel pipeline while performing magnetic flux detection on the steel pipeline includes:

[0030] The detection probe is energized by DC excitation or AC excitation to generate an excitation magnetic field, and the leakage magnetic field signal generated by the defect in the steel pipeline is collected by using the power excitation and acquisition module;

[0031] Receive and read the leakage magnetic field signal collected by the power supply excitation and acquisition module, convert and display the leakage magnetic field signal;

[0032] Calculating the frequency of the leakage magnetic field signal, and performing orthogonal demodulation on the leakage magnetic field signal according to the signal frequency to determine the amplitude and phase change of the leakage magnetic field signal;

[0033] Performing filtering and denoising processing on the leakage magnetic field signal, encoding and position alignment on the leakage magnetic field signal after filtering and denoising, and determining the amplitude and width of the leakage magnetic field signal;

[0034] The defect position of the steel pipeline is determined according to the leakage magnetic field signal, and the defect size is graded according to the signal amplitude and width of the defect position.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) This method has high accuracy and can detect even tiny surface defects that account for only one-sixth of the thickness of the steel pipe surface. Under the premise of ensuring the accuracy of the test results, the lifting height can reach 30-50mm, which perfectly solves the problem of detecting steel pipes with thick coatings;

[0037] (2) The probe is small and easy to assemble. The winding device can be used to quickly wind the wire. The coil skeleton can be split into two and directly put on the steel pipe. The linear magnetic field sensor is directly assembled on the coil skeleton.

[0038] (3) The host computer can clearly identify the amplitude and width of the defect signal through filtering and denoising and decoding and alignment of the displacement sensor, making it easier to calculate the defect depth and surface size of the damaged area, realize graded damage treatment, and promptly detect and repair serious damage;

[0039] (4) When DC excitation is not applicable, AC excitation can be used. Through the orthogonal demodulation algorithm in the host computer, the amplitude and phase changes of the alternating voltage signal can be clearly seen, thereby deducing the size and location of the defect. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the framework structure of a non-contact detection device for steel pipe body damage based on magnetic flux disclosed in an embodiment of the present invention;

[0041] Figure 2 A schematic structural diagram of a wire winding platform disclosed in one embodiment of the present invention;

[0042] Figure 3 A schematic structural diagram of a test platform disclosed in one embodiment of the present invention;

[0043] Figure 4 A schematic structural diagram of an experimental principle disclosed in one embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram of an implementation of the orthogonal demodulation portion of the signal processing host computer interface diagram disclosed in one embodiment of the present invention;

[0045] Figure 6 This is a schematic diagram of the implementation of the filtering, displacement coding and defect classification parts in the signal processing host computer interface diagram disclosed in an embodiment of the present invention.

[0046] In the figure, the corresponding relationship between each component and the reference numeral is as follows:

[0047] 1. Hardware platform; 2. Power supply management module; 3. Magnetic linear sensor power supply; 4. Stepper motor drive power supply; 5. DC motor power supply; 6. Power amplifier power supply; 7. 51 chip power supply; 8. Power excitation and acquisition module; 9. DC power supply; 10. AC power supply; 11. Power amplifier; 12. Preamplifier; 13. Final power amplifier; 14. Drive amplifier; 15. Detection probe; 16. Coil skeleton; 17. Excitation coil; 18. Magnetic linear sensor; 19. A / D conversion module; 20. Voltage signal acquisition module; 21. Test platform; 22. Rising edge reading; 23. Pulse generation; 24. Displacement sensor; 25. DC motor; 26. PWM generation; 27. Motor driver module; 28. Winding platform; 29. Stepper motor; 30. PWM speed control module Block; 31. Steel pipe; 32. Wire winding bracket; 33. Probe fixing bracket; 34. Signal processing host computer; 35. Signal reading module; 36. Signal display module; 37. Frequency detection module; 38. Orthogonal demodulation module; 39. Mean filter module; 40. Median filter module; 41. Displacement encoding module; 42. Data alignment module; 43. Defect location module; 44. Defect classification module; 45. Wire winding fixing bracket; 46. Probe skeleton fixing rotor; 47. Enameled wire fixing bracket; 48. Coupling; 49. Enameled wire skeleton; 50. Support shaft; 51. Special table; 52. Support bracket; 53. Slide rail; 54. Slide table; 55. Bearing seat; 56. Ball screw support; 57. Hand-crank steering wheel; 58. Ball screw; 59. Steel pipe bracket; 60. Sensor base. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0049] The present invention will be described in further detail below with reference to the accompanying drawings:

[0050] like Figures 1 to 3 As shown, a non-contact detection device for steel pipe body damage based on magnetic flux according to the present invention includes: a power supply management module 2, a power supply excitation and acquisition module 8, a winding platform 28, a test platform 21 and a signal processing host computer 34;

[0051] The power supply management module 2 supplies power to the required modules in the device. The power excitation and acquisition module 8 includes a detection probe 15. The power excitation and acquisition module 8 provides DC or AC excitation to the detection probe 15 to generate an excitation magnetic field, and collects the magnetic field signal generated by the excitation magnetic field in the steel pipeline 31 to be detected.

[0052] The winding platform 28 is used to wind the excitation coil 17 for the detection probe 15. The steel pipe 31 to be tested is fixed on the test platform 21. The detection probe 15 with the excitation coil 17 wound around it is set outside the steel pipe 31 and can move along the steel pipe 31 to perform overall magnetic flux detection on the steel pipe 31.

[0053] The detection probe 15 is connected to the signal processing host computer 34 . The signal processing host computer 34 performs data processing based on the magnetic field signal collected by the detection probe 15 , and analyzes and obtains defect information on the steel pipeline 31 .

[0054] In this embodiment, the power excitation and acquisition module 8 and the signal processing host computer 34 collect and process the leakage magnetic signal of the steel pipe 31 in the excitation magnetic field. Under the premise of ensuring the accuracy of the detection results, the lifting height can reach 30-50 mm, which perfectly solves the problem of detecting steel pipes with thicker coating layers. In addition, the defect position and defect size of the steel pipe 31 can be obtained through signal processing, so that the defect damage can be discovered in time and repaired. Through the combination of the test platform 21 and the winding platform 28, rapid winding and rapid detection can be achieved, and the assembly is convenient and the detection efficiency is high.

[0055] The device is divided into a hardware platform 1 and a signal processing host computer 34, which serves as a software platform. The hardware platform 1 and the signal processing host computer 34 are connected via a lockable Type A-USB cable. The hardware platform 1 comprises a power management module 2, a power excitation and acquisition module 8, and a test platform 21. The power management module 2 is connected to the power excitation and acquisition module 8 and the test platform 21 via power buses. The power management module 2 includes a magnetic linear sensor power supply 3, a stepper motor drive power supply 4, a DC motor power supply 5, a power amplifier power supply 6, and a 51 chip power supply 7. These power buses are used to supply power to the power amplifier 11, the voltage signal acquisition module 20, the DC motor 25 (optional model JGB37), the stepper motor 29 (optional model 57HS22), and the control pulse generator 23 and the 51 chip 7 that controls and adjusts the speed of the stepper motor 29 in the bobbin winder.

[0056] Specifically, in the above embodiment, preferably, the power excitation and acquisition module 8 also includes a DC power supply 9, an AC power supply 10, a power amplification module, an A / D conversion module 19 and a voltage signal acquisition module 20. The DC power supply 9 and the AC power supply 10 provide DC and AC excitation modes for the detection probe 15. The AC power supply 10 is connected to the detection probe 15 through the power amplification module for power amplification. The detection probe 15 performs analog-to-digital conversion through the A / D conversion module 19. The voltage signal acquisition module 20 is used to collect the voltage signal of the detection probe 15.

[0057] The power excitation and acquisition module 8 is used to power all devices that require power. It can use two excitation methods for the detection probe 15: one is to use the DC power supply 9 to directly power the excitation coil 17, and the other is to use the AC power supply 10. Because the power of the AC power supply 10 is relatively low, the AC voltage needs to be amplified by the power amplifier 11 to generate a larger current and excitation magnetic field. The power amplifier 11 contains three parts, including: preamplifier 12, driver amplifier 14, and final power amplifier 13.

[0058] like Figure 4 Specifically, when current flows through the excitation coil 17, an excitation magnetic field is generated. Direct current generates a fixed magnetic field, while alternating current generates an alternating magnetic field. Regardless of the magnetic field, the purpose of magnetizing the defective steel pipe 31 can be achieved. When the magnetic field in the steel pipe is free of defects, it is confined to the pipe wall. However, when the magnetic field lines encounter a defect, the magnetic lines of force are projected from the high-permeability steel pipe into the low-permeability air, causing compression and dissipation of the magnetic lines of force, thereby generating a leakage magnetic field above the defect. This leakage magnetic field is collected and analyzed by the magnetic linear sensor 18, and the presence of defects in the steel pipe 31, as well as the location and size of the defects, can be determined based on the waveform characteristics.

[0059] In the above embodiment, preferably, the test platform 21 includes a support frame 52, a ball screw 58, a slide rail 53, a slide 54, a hand-cranked steering wheel 57, a steel pipe bracket 59, a probe fixing bracket 33 and a displacement sensor 24. The ball screw 58 and the slide rail 53 are fixed in parallel to the support frame 52. Specifically, a load-bearing seat 55 is provided on both sides of the support frame 52. The ball screw 58 is fixed to the load-bearing seat 55 through a ball screw support 56. The slide 54 is respectively sleeved on the ball screw 58 and the slide rail 53. The hand-cranked steering wheel 57 is fixed to the ball screw 58 and realizes the linear translation movement of the slide 54 under the rotation of the hand-cranked steering wheel 57.

[0060] The steel pipe 31 to be inspected is fixed on the steel pipe bracket 59, and the detection probe 15 is fixed to the slide 54 via the probe fixing bracket 33. The detection area of the detection probe 15 corresponds to the steel pipe 31 and moves along the steel pipe 31 with the slide 54, realizing the overall monitoring of the steel pipe 31;

[0061] The displacement sensor 24 is fixed on the slide 54 and is used to monitor the displacement of the detection probe 15 relative to the steel pipe 31 .

[0062] Specifically, the entire support frame 52 of the test platform 21 is composed of an aluminum alloy frame, equipped with both straight and right-angle adapters for connecting to the slide rails 53. The slide 54 is divided into two parts: an upper slide that supports the displacement sensor 24 and detection probe 15, and a lower slide that supports the defective steel pipe 31. These two slides allow the test platform 21 to fix steel pipes of any size and length and ensure smooth movement of the detection probe 15 on the steel pipe 31. Rotating the hand-cranked steering wheel 57 controls the rotation of the ball screw 58, driving the slide 54 to translate along the slide rails 53.

[0063] In the above embodiment, preferably, the wire winding platform 28 includes a stepper motor 29, a wire winding bracket 32, a probe skeleton fixed rotor 46, a DC motor 25 and an enameled wire skeleton 49, the stepper motor 29 is fixed to the wire winding bracket 32, the probe skeleton fixed rotor 46 is fixed to the rotor of the stepper motor 29, and the detection probe 15 is mounted on the probe skeleton fixed rotor 46;

[0064] The DC motor 25 is fixed on the winding bracket 32, and the enameled wire skeleton 49 is fixed on the rotor of the DC motor 25;

[0065] Driven by the stepping motor 29 and the DC motor 25 , the enameled wire wound on the enameled wire skeleton 49 is wound on the detection probe 15 according to the preset parameters of the excitation coil 17 .

[0066] Specifically, the winding platform 28 utilizes the rotational motion of the rotating body to wind the excitation coil 17 around the coil bobbin 16 of the detection probe 15. The power supply 4 of the stepper motor 29 in the power management module 2 is connected to the motor drive module 27. The motor drive module 27 is connected to the DC motor 25 and the stepper motor 29, respectively. The torque of the stepper motor 29 can be controlled by adjusting the voltage of the motor drive module 27. Since the motor drive module 27 requires a voltage of 12-40V, a DC power supply 9 is used to power the stepper motor 29. Controlling the stepper motor 29 requires the use of a PWM wave. The speed of the stepper motor 29 can be adjusted by changing the PWM wave frequency and the subdivision number of the motor drive module 27. The subdivision number and rated current in the motor drive module 27 are modified. A larger subdivision number results in less noise and smoother rotation. The PWM wave frequency in the PWM generator 26 (89C51) is adjusted through the PWM speed control module 30 to select an appropriate motor speed for a smooth winding process. Therefore, a PWM generator 26 (89C51) is used to generate a PWM pulse signal with adjustable frequency to achieve the purpose of controlling the speed of the stepping motor 29.

[0067] Specifically, during the implementation process, the above-mentioned components carried by the DC power supply 9 and the wire winding bracket 32 are fixed on a special table 51, and the probe skeleton fixed rotor 46 is supported by the wire winder fixed bracket 45 at the other end relative to the stepper motor 29. The enameled wire skeleton 49 is integrally mounted on the support shaft 50 and is connected to the rotor of the DC motor 25 through the coupling 48. The enameled wire wound on the enameled wire skeleton 49 is fixed by the enameled wire fixing bracket 47 to ensure that the enameled wire will not be tangled during the winding process.

[0068] In the above embodiment, preferably, the coil skeleton 16 of the detection probe 15 is a circular ring structure, and the coil skeleton 16 is a detachable combined structure. During the winding process, the coil skeleton 16 is assembled and sleeved on the probe skeleton fixed rotor 46. During the magnetic flux detection process, the coil skeleton 16 is assembled and sleeved outside the steel pipe 31 and fixed on the probe fixed bracket 33, so that the detection probe 15 can move translationally along the steel pipe 31 with the slide 54.

[0069] In the above embodiment, preferably, the displacement sensor 24 adopts a pull-rope displacement sensor, which includes a sensor base 60, a grating sensor and a turntable (not shown in the figure). The turntable is fixed on the sensor base 60, and the sensor base 60 is fixed relative to the support frame 52. The pull rope of the turntable moves along the steel pipe 31 with the detection probe 15, and the grating sensor detects the extension and contraction of the pull rope to determine the displacement of the detection probe 15 relative to the steel pipe 31.

[0070] Specifically, the displacement sensor 24 is secured to the lower slide rail 53 via a sensor base 60 and a slide 54. The sensor base 60 is replaceable to accommodate steel pipes 31 of varying lengths. This ensures that the pull cord of the displacement sensor 24 remains parallel to the steel pipe 31, minimizing errors. Because the pulse signal output by the grating sensor is relatively weak and difficult to calculate using algorithms, this embodiment incorporates a rising edge reading module 22 and a pulse generation module 23 for pulse reconstruction to generate regular pulse waves that are easily calculated using algorithms.

[0071] In the above embodiment, preferably, a lot of functions are integrated into the signal processing host computer 34, and the data is transmitted from the power excitation and acquisition module 8 through a lockable Type A-USB cable. Using the signal reading algorithm, the baud rate of the serial port is first set, and then the signal demodulation method is set. Through these two, the voltage output from the voltage acquisition module can be successfully read. The voltage includes two parts, one is the magnetic field signal in the magnetic linear sensor 18 along the axial direction of the steel pipe 31 and the normal direction of the steel pipe 31, and the other is the displacement signal output from the displacement sensor 24.

[0072] Specifically, the signal processing host computer 34 includes a signal reading module 35, a signal display module 36, a frequency detection module 37, an orthogonal demodulation module 38, a mean filter module 39, a median filter module 40, a displacement encoding module 41, a data alignment module 42, a defect location module 43 and a defect classification module 44;

[0073] The signal reading module 35 is used to receive and read the signal collected by the power supply excitation and acquisition module 8. The signal display module 36 is used to convert and display the signal received by the signal reading module 35. Preferably, the PlotWidget module in Qt Designer is used. This module can display a two-dimensional coordinate system and draw various signal graphs on it.

[0074] like Figure 5 As shown, the frequency detection module 37 is used to calculate the frequency of the signal. Specifically, FFT transformation can be used. The frequency of the alternating signal can be quickly obtained through fast Fourier transform. The orthogonal demodulation module 38 is used to perform orthogonal demodulation on the signal according to the frequency of the signal to determine the amplitude and phase change of the signal, that is, the signal of the defect position;

[0075] like Figure 6As shown, the mean filter module 39 and the median filter module 40 are used to filter and de-noise the signal. Since the collected voltage signal is noisy when using DC power supply 9 for excitation, the mean and median filters are used to filter and de-noise the signal to obtain a smooth voltage curve. The displacement encoding module 41 and the data alignment algorithm are used to encode and align the filtered and de-noised signal to determine the signal amplitude and width.

[0076] The defect location module 43 determines the defect location based on the position-aligned signal, while the defect grading module 44 grades the defect size based on the amplitude and width of the defect location. Specifically, after utilizing a displacement encoding algorithm and a data alignment algorithm, the collected displacement pulse signals are counted. This number represents the rotation angle of the displacement sensor 24's turntable. Multiplying this number by the turntable's diameter reveals the position of the detection probe 15 on the steel pipe 31. The position signal is then aligned with the magnetic linear sensor 18 to calculate the amplitude and width of the defect signal.

[0077] The present invention further provides a non-contact detection method for steel pipe body damage based on magnetic flux, which is applied to the non-contact detection device for steel pipe body damage based on magnetic flux disclosed in any of the above embodiments, comprising:

[0078] After determining the number of turns of the excitation coil 17 and the diameter of the enameled wire used according to the required lift-off distance, the thickness of the excitation coil and the distance between the excitation coils, the excitation coil 17 is wound around the detection probe 15 using the winding platform 28;

[0079] The detection probe 15 wrapped with the excitation coil 17 is fixed to a preset position on the test platform 21, the steel pipe 31 to be tested is fixed to the steel pipe bracket 59, and the end of the pull rope of the displacement sensor 24 is fixed to the detection probe 15. The displacement sensor 24 is used to detect the displacement of the detection probe 15 relative to the steel pipe 31 to be tested. Specifically, the five signal lines of the grating sensor are connected to the rising edge reading module 22, and then the pulse generator Arduino 23 is used to generate pulses. The main function is to detect the tiny pulse emitted by the grating sensor and amplify the pulse to 5V for a maintenance time of 0.3ms, so that the displacement encoding module 41 in the signal processing host computer 34 can perform displacement calculation;

[0080] The magnetic linear displacement sensor 24 is fixed to the coil skeleton 16 of the detection probe 15 and powered by the magnetic linear displacement sensor 24 power supply module of the power supply management module 2 at a voltage of 5V. The signal lines in the axial and perpendicular directions are connected to the voltage signal acquisition module 20. When using the DC power supply 9 for excitation, the two ends of the excitation coil 17 can be directly connected to the DC power supply 9. When using the AC power supply 10 for excitation, the AC power needs to be connected to the power amplifier module first to amplify the voltage and current, and then connected to the excitation coil 17.

[0081] The detection probe 15 is driven to translate along the steel pipe 31 while performing magnetic flux detection on the steel pipe 31 , and the displacement of the detection probe 15 relative to the steel pipe 31 is synchronously detected;

[0082] The detection signal of the detection probe 15 and the displacement signal of the displacement sensor 24 are collected, and the defect information and the defect position of the steel pipeline 31 are determined according to the detection signal and the displacement signal.

[0083] In the above embodiment, preferably, in the process of using the winding platform 28 to wind the excitation coil 17 on the detection probe 15, the stepper motor 29 is controlled to drive the probe skeleton fixed rotor 46 to rotate according to a preset method, and the DC motor 25 is controlled to drive the enameled wire skeleton 49 to rotate according to a preset method, so that the enameled wire is smoothly wound on the detection probe 15 according to the required lifting distance, excitation coil thickness and the distance between the two excitation coils.

[0084] In the above embodiment, preferably, the specific process of driving the detection probe 15 to translate along the steel pipe 31 while performing magnetic flux detection on the steel pipe 31 and determining the defect information and defect location of the steel pipe 31 based on the detection signal and the displacement signal includes:

[0085] The detection probe 15 is powered by DC excitation or AC excitation to generate an excitation magnetic field, and the power excitation and acquisition module 8 is used to collect the leakage magnetic field signal generated by the defect in the steel pipe 31;

[0086] Receive and read the leakage magnetic field signal collected by the power supply excitation and acquisition module 8, convert and display the leakage magnetic field signal;

[0087] Calculate the frequency of the leakage magnetic field signal, and perform orthogonal demodulation on the leakage magnetic field signal according to the signal frequency to determine the amplitude and phase change of the leakage magnetic field signal;

[0088] Performing filtering and denoising on the leakage magnetic field signal, encoding and position alignment on the filtered and denoised leakage magnetic field signal, and determining the amplitude and width of the leakage magnetic field signal;

[0089] The defect position of the steel pipeline 31 is determined based on the leakage magnetic field signal, and the defect size is classified based on the signal amplitude and width at the defect position.

[0090] Among them, in the specific signal processing and calculation process:

[0091] Use the orthogonal demodulation algorithm to decompose the alternating signal. Assume that the output voltage signal is U0, which is the original AC signal U i and the change signal U caused by the defect d So the expression of U0 is:

[0092]

[0093] After demodulation, U0 is divided into an in-phase signal I and a quadrature signal Q. The in-phase signal is obtained by multiplying the detection signal by the carrier signal and low-pass filtering. The quadrature signal is obtained by multiplying the detection signal by the carrier signal after 90° phase shift and then low-pass filtering. The carrier signal is cos(wt), and the specific calculation process is as follows:

[0094]

[0095]

[0096] After low-pass filtering:

[0097]

[0098]

[0099] The amplitude and phase of the defect signal can be obtained by the following calculation.

[0100]

[0101]

[0102] Furthermore, the voltage signal is smoothed using the median filter algorithm. Before using the median filter algorithm, the filter window size must be set. The filter window should not be too large or too small. If it is too small, the curve will not be smooth enough, and if it is too large, the defect information will be lost. Assuming that the input is x and the output is y, the calculation formula of the mean filter is as follows:

[0103]

[0104] Furthermore, the method used to count the number of pulses during displacement encoding is to subtract the previous voltage signal from the next voltage signal. If the difference is greater than the set threshold, it is considered a pulse. Assuming that the number of pulses is n, the distance between the end of the rope of the displacement sensor 24 and the end of the steel pipe is a, the diameter of the turntable is d, the position of the probe on the steel pipe is z, and the grating sensor used has 600 pulses per rotation, the expression of z is:

[0105]

[0106] Finally, after aligning the displacement and voltage signals, the defect size level is determined by judging the amplitude and width of the defect signal.

[0107] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A non-contact detection device for steel pipe body damage based on magnetic flux, characterized in that: include: Power supply management module, power supply excitation and acquisition module, winding platform, test platform and signal processing host computer; The power supply management module supplies power to the required modules in the device. The power supply excitation and acquisition module includes a detection probe. The power supply excitation and acquisition module provides DC or AC excitation to the detection probe to generate an excitation magnetic field, and collects the magnetic field signal generated by the excitation magnetic field in the steel pipeline to be detected; The winding platform is used to wind the excitation coil for the detection probe. The steel pipeline to be detected is fixed on the test platform. The detection probe wound with the excitation coil is arranged on the outside of the steel pipeline and can move along the direction of the steel pipeline to perform overall magnetic flux detection on the steel pipeline. The detection probe is connected to the signal processing host computer, and the signal processing host computer performs data processing according to the magnetic field signal collected by the detection probe, and analyzes and obtains the defect information on the steel pipeline; The test platform includes a support frame, a ball screw, a slide rail, a slide table, a hand-cranked steering wheel, a steel pipe bracket, a probe fixing bracket and a displacement sensor. The ball screw and the slide rail are fixed in parallel to the support frame, and the slide table is respectively sleeved on the ball screw and the slide rail. The hand-cranked steering wheel is fixed to the ball screw and realizes linear translation movement of the slide table when the hand-cranked steering wheel is rotated. The steel pipe to be inspected is fixed on the steel pipe support, and the inspection probe is fixed on the slide via the probe fixing bracket. The inspection area of the inspection probe corresponds to the steel pipe and moves along the steel pipe with the slide, thereby realizing overall monitoring of the steel pipe. The displacement sensor is fixed on the slide and is used to monitor the displacement of the detection probe relative to the steel pipe; The winding platform includes a stepping motor, a winding bracket, a probe skeleton fixed rotor, a DC motor and an enameled wire skeleton, the stepping motor is fixed on the winding bracket, the probe skeleton fixed rotor is fixed on the rotor of the stepping motor, and the detection probe is installed on the probe skeleton fixed rotor; The DC motor is fixed on the wire winding bracket, and the enameled wire skeleton is fixed on the rotor of the DC motor; Driven by the stepping motor and the DC motor, the enameled wire wound on the enameled wire skeleton is wound on the detection probe according to preset excitation coil parameters.

2. The non-contact detection device for steel pipe body damage based on magnetic flux according to claim 1 is characterized in that: The power excitation and acquisition module also includes a DC power supply, an AC power supply, a power amplifier module, an A / D conversion module and a voltage signal acquisition module. The DC power supply and the AC power supply provide DC and AC excitation modes for the detection probe. The AC power supply is connected to the detection probe through the power amplifier module for power amplification. The detection probe performs analog-to-digital conversion through the A / D conversion module. The voltage signal acquisition module is used to collect the voltage signal of the detection probe.

3. The non-contact detection device for steel pipe body damage based on magnetic flux according to claim 1 is characterized in that: The signal processing host computer includes a signal reading module, a signal display module, a frequency detection module, an orthogonal demodulation module, a mean filter module, a median filter module, a displacement coding module, a data alignment module, a defect location module and a defect classification module; The signal reading module is used to receive and read the signal collected by the power supply excitation and acquisition module, and the signal display module is used to convert and display the signal received by the signal reading module; The frequency detection module is used to calculate the frequency of the signal, and the orthogonal demodulation module performs orthogonal demodulation on the signal according to the frequency of the signal to determine the amplitude and phase change of the signal; The mean filter module and the median filter module are used to filter and denoise the signal, and the displacement coding module and the data alignment algorithm are used to encode and position align the filtered and denoised signal to determine the amplitude and width of the signal; The defect location module is used to determine the defect location according to the position alignment signal, and the defect classification module is used to classify the defect size according to the amplitude and width of the defect location.

4. The non-contact detection device for steel pipe body damage based on magnetic flux according to claim 1 is characterized in that: The coil frame of the detection probe is a circular ring structure, and the coil frame is a detachable combined structure. During the winding process, the coil frame is assembled and sleeved on the probe frame fixed rotor. During the magnetic flux detection process, the coil frame is assembled and sleeved outside the steel pipe and fixed on the probe fixed bracket, so that the detection probe can move translationally along the steel pipe with the slide.

5. The non-contact detection device for steel pipe body damage based on magnetic flux according to claim 1, characterized in that: The displacement sensor adopts a pull-rope displacement sensor, which includes a sensor base, a grating sensor and a turntable. The turntable is fixed on the sensor base, and the sensor base is fixed relative to the support frame. The pull rope of the turntable moves along the steel pipeline with the detection probe. The grating sensor detects the expansion and contraction of the pull rope to determine the displacement of the detection probe relative to the steel pipeline.

6. A non-contact detection method for steel pipe body damage based on magnetic flux, characterized in that: A non-contact detection device for steel pipe body damage based on magnetic flux, as used in any one of claims 1 to 5, comprising: According to the required lift-off distance, excitation coil thickness and excitation coil distance, the detection probe is wound with the excitation coil using the winding platform; Fixing the detection probe wound with the excitation coil at a preset position on the test platform, and using a displacement sensor to detect the displacement of the detection probe relative to the steel pipe to be detected; driving the detection probe to translate along the steel pipeline while performing magnetic flux detection on the steel pipeline, and synchronously detecting the displacement of the detection probe relative to the steel pipeline; The detection signal of the detection probe and the displacement signal of the displacement sensor are collected, and the defect information and the defect position of the steel pipeline are determined according to the detection signal and the displacement signal.

7. The non-contact detection method for steel pipe body damage based on magnetic flux according to claim 6, characterized in that: In the process of using the winding platform to wind the excitation coil on the detection probe, the stepper motor is controlled to drive the probe frame fixed rotor to rotate according to a preset method, and the DC motor is controlled to drive the enameled wire frame to rotate according to a preset method, so that the enameled wire is smoothly wound on the detection probe according to the required lifting distance, excitation coil thickness and distance between the two excitation coils.

8. The non-contact detection method for steel pipe body damage based on magnetic flux according to claim 6, characterized in that: The specific process of driving the detection probe to translate along the steel pipeline while performing magnetic flux detection on the steel pipeline includes: The detection probe is powered by DC excitation or AC excitation to generate an excitation magnetic field, and the leakage magnetic field signal generated by the defect in the steel pipeline is collected by using the power excitation and acquisition module; Receive and read the leakage magnetic field signal collected by the power supply excitation and acquisition module, convert and display the leakage magnetic field signal; Calculating the frequency of the leakage magnetic field signal, and performing orthogonal demodulation on the leakage magnetic field signal according to the signal frequency to determine the amplitude and phase change of the leakage magnetic field signal; Performing filtering and denoising processing on the leakage magnetic field signal, encoding and position alignment on the leakage magnetic field signal after filtering and denoising, and determining the amplitude and width of the leakage magnetic field signal; The defect position of the steel pipeline is determined according to the leakage magnetic field signal, and the defect size is graded according to the signal amplitude and width of the defect position.

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