A magnetic field detection and imaging system for steel plate deformation

Abstract

The present invention relates to a magnetic field detection and imaging system for steel plate deformation, which consists of a host computer composed of a power conversion module, a signal generation module, a power amplification module, and a data acquisition module; a sensing device composed of a drive module, a Hall element, a magnetic yoke, an excitation coil, and an extended connection device; and these two parts together with a digital signal processing and imaging module constitute the overall architecture of the system. After determining the arrangement mode and number of the sensing devices through the extended connection device according to the flaw detection object, each module is powered on. The host computer provides a power-amplified excitation source for the sensing device, the drive module drives the sensing device to move forward, the Hall element moves for scanning, and the signals at the normal and defective positions on the steel plate surface are transmitted back to the host computer in real time for data acquisition, converting the analog signals into digital signals, and then transmitting them to the digital signal processing and imaging module to feedback the damage through the phase and amplitude comparison algorithm, greatly improving the detection efficiency, reducing the missed detection rate, and making the feedback information more intuitive and accurate.

Description

Technical Field

[0001] The present invention belongs to the field of low-frequency magnetic flux leakage detection, and particularly relates to a magnetic field detection and imaging system for steel plate deformation. Background Art

[0002] Ferromagnetic materials are widely used in pressure-bearing equipment in fields such as petroleum, chemical industry, and electric power due to their high strength, good plasticity, impact resistance, and reliable performance. However, during the long-term service of these pressure-bearing equipment, under the combined action of the external environment and internal load-bearing media, various damages such as cracks and corrosion are likely to occur on the inner and outer walls of the pressure-bearing equipment, endangering the safe operation of the structure. Therefore, it is of great significance to quickly detect and diagnose them early. To ensure the normal operation of pressure-bearing equipment and prevent the occurrence of serious accidents, it is very necessary to develop effective non-destructive testing methods for ferromagnetic pressure-bearing equipment. For the detection of defects such as corrosion, existing non-destructive testing methods such as radiography, ultrasonic, magnetic particle, and penetrant have their own deficiencies in adapting to the high and low temperature environments on-site, the surface conditions of equipment, etc. For example: ① It is necessary to have good coupling with the metal body to enable ultrasonic waves to be transmitted and received between the sensor and the metal body; ② Generally, it is for the measurement of the wall thickness at a certain point and is not suitable for large-area scanning detection, so the detection speed is very slow. Therefore, it is very necessary to develop a non-destructive testing method that has low requirements for the surface, preferably has a certain lift-off, is fast, portable, and has relatively high sensitivity. The low-frequency electromagnetic detection method is based on the eddy current or magnetic flux leakage principle and uses a non-contact method to detect surface and buried defects of the equipment to be inspected. Especially for volumetric defects such as corrosion, it has relatively high detection sensitivity, so it is very suitable for on-line detection of pressure-bearing equipment such as pipelines.

[0003] Currently, the low-frequency magnetic flux leakage detection devices widely existing and used on the market generally have disadvantages such as low detection efficiency, high missed detection rate, poor environmental adaptability, and unclear imaging feedback information. Summary of the Invention

[0004] To solve the above technical problems, the object of the present invention is to provide a magnetic field detection and imaging system with high efficiency, high coverage rate, strong adaptability to complex environments, and rich and comprehensive imaging feedback information.

[0005] The technical solution of the present invention is as follows: A magnetic field detection and imaging system, characterized in that it consists of a host (1), a digital signal processing and imaging module (2), and a sensing device (3). The host (1) includes a power conversion module (101), a signal generation module (102), a power amplification module (103), and a data acquisition module (104); the sensing device (3) includes a drive module (301), a Hall element (302), a yoke (303), an excitation coil (304), and an extended connection device (305). The power conversion module (101) converts 220V alternating current into 5V direct current and transmits it to the sensing device (3) and the signal generation module (102), and converts it into 15V alternating current and transmits it to the power amplification module (103); the drive module (301) drives the sensing device (3) to move; the signal generation module (102) is a two-channel sine signal generator controlled by an STM32F103RCT6 single-chip microcomputer, and generates an analog sine wave with adjustable amplitude and frequency by controlling PWM as the input end and is connected to the power amplification module (103). The power amplification module (103) amplifies the sine signal and inputs it into the excitation coil (304) fixed on the yoke (303) as the excitation source; the data acquisition module (104) consists of a data acquisition card, which converts the analog signal sensed by the Hall element (302) into a digital signal and transmits it to the digital signal processing and imaging module (2). The Hall element (302) is an SS94A1 Hall effect sensor very suitable for detecting weak magnetic field signals. The digital signal processing and imaging module (2) is supported by a program developed by LabVIEW, and accurately calculates the specific position, shape, and damage degree of the defect by integrating the phase comparison algorithm and the amplitude comparison algorithm. At the same time, it performs calculation and simulation to draw a three-dimensional map of the damage, intuitively displaying the specific damage information. In this system, the core chip of the power amplification module (103) is an LM3886 power amplifier chip; the yoke (303) is a U-shaped yoke, and its two arms are respectively fixed with the excitation coil (304); in particular, each sensing device (3) only has a row of drive wheels and is equipped with an extended connection device (305), and several sensing devices (3) can be connected in parallel according to the size of the steel plate for high-efficiency carpet detection or several sensing devices (3) can be connected end to end according to the size of the steel pipe for 360-degree one-time comprehensive detection, greatly improving the detection efficiency and reducing the missed detection rate.

[0006] The beneficial effects of the present invention are as follows:

[0007] The extended connection device of this system can expand the detection efficiency at low cost and reduce the missed detection rate.

[0008] This system combines the phase comparison algorithm and the amplitude comparison algorithm, improving the detection accuracy and the detectable depth.

[0009] The imaging concept of this system can restore the actual situation of damage, enabling users to intuitively obtain damage information

[0010] The signal frequency adjustability of this system can adapt to various steel plates and steel pipes with different thicknesses, being more flexible. Brief Description of the Drawings

[0011] Figure 1 It is a schematic diagram of the overall architecture of the magnetic field detection and imaging system for the deformation of this steel plate;

[0012] Figure 2 It is a schematic diagram of the extended connection device of the magnetic field detection and imaging system for the deformation of this steel plate;

[0013] Figure 3 It is a schematic diagram of the imaging principle of the magnetic field detection and imaging system for the deformation of this steel plate; Detailed Embodiments

[0014] The following specifically describes the embodiments of the present invention in conjunction with the drawings.

[0015] Figure 1A magnetic field detection and imaging system for steel plate deformation shown in the figure consists of a host computer (1), a digital signal processing and imaging module (2), and a sensing device (3); among them, the host computer (1) includes a power conversion module (101), a signal generation module (102), a power amplification module (103), and a data acquisition module (104); the sensing device (3) includes a drive module (301), a Hall element (302), a magnetic yoke (303), an excitation coil (304), and an extended connection device (305). The power conversion module (101) converts 220V alternating current into 5V direct current and transmits it to the sensing device (3) and the signal generation module (102), and converts it into 15V alternating current and transmits it to the power amplification module (103); the drive module (301) drives the sensing device (3) to move; the signal generation module (102) is a two-channel sine signal generator controlled by an STM32F103RCT6 single-chip microcomputer, and generates an analog sine wave with adjustable amplitude and frequency by controlling PWM as the input end and is connected to the power amplification module (103). The power amplification module (103) amplifies the sine signal and inputs it into the excitation coil (304) fixed on the magnetic yoke (303) as the excitation source; the data acquisition module (104) consists of a data acquisition card, which converts the analog signal sensed by the Hall element (302) into a digital signal and transmits it to the digital signal processing and imaging module (2). The Hall element (302) is an SS94A1 Hall effect sensor very suitable for detecting weak magnetic field signals. The digital signal processing and imaging module (2) is supported by a program developed by LabVIEW, and accurately calculates the specific position, shape, and damage degree of the defect by integrating the phase comparison algorithm and the amplitude comparison algorithm. At the same time, it performs calculation simulation and draws a three-dimensional map of the damage to intuitively display the specific damage information. In this system, the core chip of the power amplification module (103) is an LM3886 power amplifier chip; the magnetic yoke (303) is a U-shaped magnetic yoke, and its two arms are respectively fixed with the excitation coil (304); in particular, each sensing device (3) only has a row of drive wheels and is equipped with an extended connection device (305). A number of sensing devices (3) can be connected side by side according to the size of the steel plate for high-efficiency carpet detection, and the sensing devices (3) can be connected end to end according to the size of the steel pipe for a one-time 360-degree comprehensive detection, greatly improving the detection efficiency and reducing the missed detection rate.

Claims

1. A magnetic field detection and imaging system for steel plate deformation, which consists of a host computer (1), a digital signal processing and imaging module (2), and a sensing device (3); wherein the host computer (1) includes a power conversion module (101), a signal generation module (102), a power amplification module (103), and a data acquisition module (104); the sensing device (3) includes a drive module (301), a Hall element (302), a magnetic yoke (303), an excitation coil (304), and an extended connection device (305); the power conversion module (101) converts 220V alternating current into 5V direct current and transmits it to the sensing device (3) and the signal generation module (102), and converts it into 15V alternating current and transmits it to the power amplification module (103); the drive module (301) drives the sensing device (3) to move. Each drive module (301) of the sensing device (3) has only one row of drive wheels and is equipped with an extended connection device (305), wherein, The driving module (301) is located at the bottom of the yoke (303), and the expansion connection device is located at the top of the yoke (303). Several sensing devices (3) can be connected side by side according to the size of the steel plate for carpet detection, and the sensing devices (3) can be connected end to end according to the diameter of the steel pipe for a one-time 360-degree comprehensive detection; the signal generation module (102) is a two-channel sine signal generator controlled by the single-chip microcomputer STM32F103RCT6. By controlling the PWM method, an analog sine wave with adjustable amplitude and frequency is generated for steel plates or steel pipes with different flaw detection depth requirements as the input end and is connected to the power amplification module (103). The adjustable signal frequency can adapt to various steel plates and steel pipes with different thicknesses; the power amplification module (103) amplifies the sine signal and inputs it into the excitation coil (304) fixed on the yoke (303) as the excitation source to enable the test piece to reach magnetic saturation. Among them, the yoke (303) is a U-shaped yoke, and its two arms are respectively fixed with the excitation coil (304); the data acquisition module (104) is composed of an 8-channel single-ended DC input and a 12-bit data acquisition card. The maximum sampling rate of each channel can reach 5 kHz, and continuous asynchronous acquisition can be realized. The analog signal sensed by the Hall element (302) is converted into a digital signal and transmitted to the digital signal processing and imaging module (2). The Hall element (302) is fixed at the geometric center of the bottom surface of the yoke (303) and is composed of an SS94A1 Hall effect sensor very suitable for detecting weak magnetic field signals. The digital signal processing and imaging module (2) is supported by a program developed by LABVIEW. By combining the phase comparison algorithm and the amplitude comparison algorithm, the non-damaged signal waveform and the defect signal waveform are compared, and the specific position, shape, and damage degree of the defect are accurately calculated. At the same time, a 3D map of the damage is drawn through calculation and simulation to intuitively display the specific damage information. By combining the phase comparison algorithm and the amplitude comparison algorithm, the detection accuracy and the detectable depth are improved.

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