Rail array eddy current automatic scanning device and detection method thereof

Abstract

The invention discloses a rail array eddy current automatic scanning device and a detection method thereof. The rail array eddy current automatic scanning device comprises a rail, a scanning device shell, a driving device, a driven wheel, a guide pulley and an upper computer based on LabVIEW. The rail is in sliding connection with the scanning device shell; the scanning device shell comprises a shell portal frame and a circuit board bin, the circuit board bin is fixedly arranged on the shell portal frame, the inner side surfaces of the shell portal frame are probe mounting surfaces, the probe mounting surfaces profile the rail head surface of a rail, and array eddy current probes are mounted on the probe mounting surfaces; the driving device and the driven wheel are installed on the front side and the rear side of the shell portal frame through supports respectively. The driving device comprises a driving wheel, a coupler, a direct current motor, a photoelectric coded disc, a control device and a wireless communication device. According to the invention, the array eddy current probe is adopted to replace a single probe, and the scanning device shell is adopted to replace manual detection, so that the detection efficiency can be obviously improved.

Description

Technical Field

[0001] The present invention relates to the field of detecting rail surface defects, and in particular to a rail array eddy current automatic scanning device and a detection method thereof. Background Art

[0002] Rails play a vital role in railway transportation. During use, they are affected by loads and erosion from the natural environment, which inevitably leads to defects such as cracks and erosion on the bearing surfaces of the rail head. Eddy current testing is an effective non-destructive testing method for such surface or near-surface defects.

[0003] For large-scale inspections such as railroad tracks, conventional eddy current inspections with manual scanning have the problem of low work efficiency. Replacing single probes with array eddy currents and manual inspections with automatic inspection devices can significantly improve inspection efficiency.

[0004] According to the principles of eddy current testing, the distance between the probe and the workpiece significantly impacts detection. Typically, detection sensitivity is highest when the probe is in close contact with the workpiece surface. However, this leads to significant wear and tear during movement. To address this issue, the present invention, while ensuring detection sensitivity, designs a scanning device probe mounting surface that aligns with the shape of the rail head, maintaining a 3mm gap and minimizing probe loss. To ensure a constant gap between the probe and each surface of the rail head during movement, guide wheels are designed for contact between the scanning device and the side of the rail head, and drive wheels are designed for contact between the scanning device and the top of the rail head. A motor drives the scanning device to move at a constant speed.

[0005] The wired connection method of traditional detection and scanning devices affects the user experience. The present invention adopts Bluetooth wireless remote control, photoelectric sensor speed measurement, and PID closed-loop control strategy to ensure that the scanning device runs at a constant speed and accurately and automatically locates defects. Summary of the Invention

[0006] The purpose of the present invention is to solve the technical problems existing in the prior art and to provide a device for automatically scanning eddy currents of a rail array and a detection method thereof.

[0007] To achieve the above-mentioned object, the present invention provides a technical solution: an automatic eddy current scanning device for a rail array, comprising a rail, a scanning device housing, a driving device, a driven wheel, a guide pulley, and a LabVIEW-based host computer; the rail is slidably connected to the scanning device housing;

[0008] The scanning device housing includes a housing gantry and a circuit board bin. The circuit board bin is fixedly mounted on the housing gantry. The inner surface of the housing gantry serves as a probe mounting surface. The probe mounting surface is contoured to the rail head surface, and a gap of 3 mm between the probe mounting surface and the rail head is formed. An array of eddy current probes is mounted on the probe mounting surface. The array of eddy current probes is positioned toward the surface of the rail to be measured and is used to scan the eddy current signals generated by the surface of the rail being measured.

[0009] The driving device and the driven wheel are respectively installed on the front and rear sides of the housing gantry through brackets. The driving device includes a driving wheel, a coupling, a DC motor, a photoelectric encoder, a control device and a wireless communication device. The driving wheel, the DC motor and the photoelectric encoder are coaxially installed. The driving wheel is connected to the DC motor through a coupling. The photoelectric encoder is installed on the output shaft end of the DC motor. The driven wheel is driven by the driving wheel.

[0010] Four supports are designed on the side of the shell gantry, and guide pulleys are installed on the supports. The gap between the probe installation surface on both sides of the shell gantry and the side of the rail head is consistent and within 3mm.

[0011] Preferably, the control device and the wireless communication device are installed in the circuit board compartment for controlling and sending speed instructions, and the photoelectric encoder is used to accurately measure the speed and position of the DC motor to achieve closed-loop control of the DC motor.

[0012] Preferably, the signal transmission process of the driving device is as follows: the host computer based on LabVIEW sends the start and speed instructions through the wireless communication device, the control device receives the instructions, and after outputting the PWM wave, the driving device controls the rotation of the DC motor. The photoelectric encoder outputs the pulse signal, which is counted and processed by the control device. When there is a deviation between the actual speed and the set speed, the PID algorithm is used to calculate the adjustment amount according to the size and change trend of the deviation, and then the pulse width of the PWM wave is adjusted.

[0013] Preferably, a probe wiring hole is provided under the circuit board compartment; a probe electronic device is provided in the circuit board compartment, and the array eddy current probe is connected to the probe electronic device through a wire passing through the probe wiring hole, and a sliding cover is provided on the circuit board compartment for sealing and disassembling the electronic device.

[0014] Preferably, the probe electronic device includes a drive and detection circuit of the array eddy current probe, a motor control circuit, a wireless transmission circuit, and a power supply battery.

[0015] The present invention also discloses a scanning method for a rail array eddy current automatic scanning device according to the above-mentioned method. The array eddy current probe is made of a flexible printed circuit board and is attached to the probe mounting surface. The array eddy current probe includes 16 flat coils directly processed on the flexible circuit board. Each group of 4 coils is a group, and each group of coils is printed in staggered layers to form 4 groups of interchangeable coil layouts, which are used to detect the top surface and two side surfaces of the rail head respectively. The 4 coils are connected as a bridge, and the output voltage is:

[0016]

[0017] Where: U O is the bridge output voltage, E is the excitation voltage, is the relative change in impedance of the first coil, is the relative change in impedance of the second coil, is the relative change in impedance of the third coil, is the relative impedance change of the fourth coil;

[0018] Since the eddy current formed under a single coil is circular, its response to defects in any direction is consistent, so that defects in any direction can always pass through any of the four coils, causing the impedance change ΔZ of the coil group. i Therefore, when there is a defect in any direction under the coil, the output voltage of the array eddy current probe is

[0019]

[0020] in: is the relative change in impedance across the defective coil;

[0021] If there are no defects under the coil, the output voltage is 0. For rough rail surfaces (such as minor pits), since these are evenly distributed on the rail surface, each coil responds consistently, so the output voltage is 0. The change in the distance between the coil and the rail surface caused by probe jitter (slight jitter) will also cause the coil impedance to change. However, since the same group of coils jitter in the same direction and the impedance change are also consistent, their output voltage remains approximately 0. Through this coil layout, the consistency of defect response in any direction is guaranteed, while suppressing the generation of interference signals such as surface roughness and slight jitter during the movement of the detection device.

[0022] Beneficial effects of the present invention:

[0023] 1. The array eddy current probe in this invention is made of a flexible printed circuit board to ensure the consistency of coil parameters; each group of four probes forms a full-bridge circuit, which not only ensures the detection sensitivity of hazardous defects such as cracks, but also effectively suppresses interference signals such as rough rail surface and jitter of the array eddy current probe, thereby improving the signal-to-noise ratio of detection.

[0024] 2. The present invention has a novel structure. The cooperation between the driving wheel and the driven wheel ensures that the present invention runs smoothly on the rail. In addition, the use of an array eddy current probe instead of a single probe and the scanning of the scanning device shell instead of manual inspection can significantly improve the inspection efficiency.

[0025] 3. While ensuring detection sensitivity, the present invention reduces the loss of the array eddy current probe by designing the probe mounting surface of the array eddy current probe to be consistent with the shape of the rail head, always maintaining a gap of 3mm for non-contact detection.

[0026] 4. The present invention adopts wireless communication device, photoelectric encoder speed measurement, and PID algorithm feedback control strategy to ensure that the automatic scanning device runs at a constant speed and realizes accurate automatic positioning of defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 It is a three-view drawing of the present invention;

[0030] Figure 3 Schematic diagram of the connection structure of the driving device in the present invention;

[0031] Figure 4 Schematic diagram of the installation surface of the flexible array eddy current probe in the present invention;

[0032] Figure 5 Schematic diagram of a group of coil layout of the flexible array eddy current probe in the present invention;

[0033] Figure 6 Schematic diagram of four coils connected as a bridge in the present invention;

[0034] Figure 7 The eddy current formed under a single coil is circular, and its response to defects in any direction is schematically shown.

[0035] Figure annotation:

[0036] 1. Driving wheel; 11. Coupling; 12. DC motor; 13. Photoelectric encoder; 2. Scanning device housing; 21. Housing gantry; 22. Circuit board compartment; 23. Probe mounting surface; 24. Cover; 3. Guide pulley; 4. Support; 5. Driven wheel; 6. Rail; 7. Array eddy current probe. DETAILED DESCRIPTION

[0037] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0038] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0039] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0040] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0041] Reference Figure 1-Figure 7 In a preferred embodiment of the present invention, a rail array eddy current automatic scanning device includes a rail 6, a scanning device housing 2, a driving device, a driven wheel 5, a guide pulley 3, and a host computer based on LabVIEW; the rail 6 is slidably connected to the scanning device housing 2;

[0042] The scanning device shell 2 includes a shell gantry 21 and a circuit board bin 22. The circuit board bin 22 is fixedly set on the shell gantry 21. The inner surface of the shell gantry 21 is a probe mounting surface 23. The probe mounting surface 23 is shaped like the rail head surface of the rail 6, and the gap between the probe mounting surface 23 and the rail head of the rail 6 is 3 mm (providing a stable detection position for the array eddy current probe 7, so that the array eddy current probe 7 can accurately detect a specific area). The probe mounting surface 23 is installed with an array eddy current probe 7. The array eddy current probe 7 is arranged along the direction of the track surface to be tested toward the rail 6, and is used to scan the eddy current signal generated on the surface of the rail 6 to be tested; the array eddy current probe 7 performs non-contact detection on the rail 6 by exciting and receiving eddy current signals, and can quickly and accurately detect defects in the rail 6.

[0043] The driving device and the driven wheel 5 are respectively installed on the front and rear sides of the housing gantry 21 through brackets. The driving device includes a DC motor 12, a driving wheel 1, a coupling 11, a photoelectric code disk 13, a control device, and a wireless communication device; the DC motor 12, the driving wheel 1, and the photoelectric code disk 13 are coaxially installed, and the driving wheel 1 is connected to the DC motor 12 through the coupling 11 (for driving the driving wheel 1 to run at a uniform speed on the rail 6). The photoelectric code disk 3 is installed at the output shaft end of the DC motor 12. The driven wheel 5 is driven by the driving wheel 1 to reduce the friction between the contact surface of the scanning device housing 2 and the rail 6 during operation; ensuring the smooth operation of the scanning device housing 2.

[0044] Four supports 4 are designed on the side of the shell gantry 21, and guide pulleys 3 are installed on the supports 4. The probe mounting surfaces 23 on both sides of the inside of the shell gantry 21 are consistent with the gap between the side of the rail head of the rail 6 and are within 3 mm. Specifically, the position of the guide pulley 3 can be adjusted during installation to ensure that the gap between the probe mounting surfaces 23 on both sides of the inside of the shell gantry 21 and the side of the rail head of the rail 6 is consistent and is 3 mm.

[0045] In this embodiment, the control device and wireless communication device are installed in the circuit board compartment 22 for controlling and sending speed instructions. The photoelectric encoder 13 is used to accurately measure the speed and position of the DC motor 12, realize closed-loop control of the DC motor 12, and improve the control accuracy and stability of the DC motor 12.

[0046] In this embodiment, the signal transmission process of the driving device is as follows: the host computer based on LabVIEW sends start and speed instructions through a wireless communication device, the control device receives the instructions, outputs a PWM wave, and then controls the rotation of the DC motor 12 through the driving device. The photoelectric encoder 13 outputs a pulse signal, which is counted and processed by the control device. When there is a deviation between the actual speed and the set speed, the PID algorithm is used to calculate the adjustment amount according to the size and change trend of the deviation, and then the pulse width of the PWM wave is adjusted to ensure speed stability.

[0047] In this embodiment, a probe wiring hole is provided under the circuit board compartment 22; a probe electronic device is provided in the circuit board compartment 22, and the array eddy current probe 7 is connected to the probe electronic device by a wire passing through the probe wiring hole, and a sliding cover 24 for sealing and disassembling the electronic device is provided on the circuit board compartment 22.

[0048] In this embodiment, the probe electronic device includes a drive and detection circuit of the array eddy current probe 7, a motor control circuit, a wireless transmission circuit, and a power supply battery.

[0049] Working principle of the present invention: The host computer of the present invention based on LabVIEW sends control signals such as start-up and speed instructions through a wireless communication device to control the operation of the present invention. The control device receives the instructions and outputs a PWM wave. The PWM wave controls the rotation of the DC motor 12 after passing through the drive device. The drive device amplifies and adjusts the PWM wave signal to meet the driving requirements of the DC motor 12. The control device counts and processes the pulse signal output by the photoelectric encoder 13 to obtain the current speed information. The PID algorithm is used to control the speed of the DC motor 12 by adjusting the pulse width of the PWM wave according to the set speed and the actual speed feedback. Through the feedback control of the photoelectric encoder 13 and the PID algorithm, it can be ensured that the present invention travels at a stable speed during the detection process, thereby improving the accuracy and reliability of the detection results.

[0050] The present invention also discloses a scanning method according to the above-mentioned rail array eddy current automatic scanning device. The array eddy current detection probe 7 is made of a flexible circuit board and is attached to the probe mounting surface 23. The array eddy current detection probe 7 includes 16 flat coils directly processed on the flexible circuit board. Each group of 4 coils is a group. Each group of coils is staggered and printed to form 4 groups of interchangeable coil layouts, such as Figure 5 As shown, the top surface and two side surfaces of the rail head of the rail 6 are detected respectively, and the four coils are connected as a bridge (as shown in FIG. Figure 6 ), its output voltage is:

[0051]

[0052] Where: U O is the bridge output voltage, E is the excitation voltage, is the relative change in impedance of the first coil, is the relative change in impedance of the second coil, is the relative change in impedance of the third coil, is the relative impedance change of the fourth coil;

[0053] Since the eddy current formed under a single coil is circular, its response to defects in any direction is consistent (e.g. Figure 7 As shown), it ensures that defects in any direction can always pass through any of the four coils, causing a change in the coil impedance ΔZ i Therefore, when there is a defect in any direction under the coil group, the output voltage of the array eddy current detection probe 7 is:

[0054]

[0055] in: is the relative change in impedance across the defective coil;

[0056] If there are no defects beneath the coils, the output voltage is 0. For rough rail surfaces (such as minor pits), since these are uniformly distributed across the rail surface, each coil responds identically, resulting in a zero output voltage. Probe vibration (slight jitter) can also cause changes in the distance between the coils and the rail surface, leading to changes in coil impedance. However, since coils within a group vibrate in the same direction, the impedance changes are also consistent, and the output voltage remains 0. This coil layout ensures consistent response to defects regardless of direction, while also suppressing interference signals such as surface roughness and slight jitter during the detection device's movement.

[0057] The present invention has a novel structure. Through the cooperation between the driving wheel 1 and the driven wheel 5, the present invention is guaranteed to run smoothly on the rail 6. The array eddy current probe 7 is used instead of a single probe, and the scanning device housing 2 replaces manual detection, which can significantly improve the detection efficiency. Secondly, on the basis of ensuring detection sensitivity, the present invention designs the probe mounting surface 23 of the array eddy current probe 7 to be consistent with the shape of the rail head of the rail 6, and always maintains a gap of 3 mm, which can reduce the loss of the array eddy current probe 7. Finally, the present invention adopts a wireless communication device, a photoelectric encoder speed measurement, and a PID algorithm feedback control strategy to ensure that the scanning device housing 2 runs at a constant speed and realizes accurate automatic positioning of defects.

[0058] In addition, the array eddy current probe 7 in the present invention is made of a flexible printed circuit board to ensure the consistency of coil parameters; each four probes form a group to form a full-bridge circuit, which not only ensures the detection sensitivity of hazardous defects such as cracks, but also can effectively suppress interference signals such as roughness and jitter on the surface of the rail 6, thereby improving the signal-to-noise ratio of detection.

[0059] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0060] The above descriptions are only preferred embodiments of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means shall fall within the scope of protection of the present invention.

Claims

1. A rail array eddy current automatic scanning device, characterized by: It comprises a rail (6), a scanning device housing (2), a driving device, a driven wheel (5), a guide pulley (3), and a host computer based on LabVIEW; the rail (6) is slidably connected to the scanning device housing (2); The scanning device housing (2) comprises a housing gantry (21) and a circuit board bin (22); the circuit board bin (22) is fixedly mounted on the housing gantry (21); the inner surface of the housing gantry (21) is a probe mounting surface (23); the probe mounting surface (23) is shaped like a rail head surface of a rail (6); and the gap between the probe mounting surface (23) and the rail head of the rail (6) is 3 mm; an array eddy current probe (7) is mounted on the probe mounting surface (23); the array eddy current probe (7) is arranged along a direction toward a rail surface to be measured of the rail (6) and is used to scan eddy current signals generated on the surface of the rail (6) to be measured; The driving device and the driven wheel (5) are respectively mounted on the front and rear sides of the housing gantry (21) through brackets, and the driving device comprises a driving wheel (1), a coupling (11), a DC motor (12), a photoelectric encoder (13), a control device and a wireless communication device; the driving wheel (1), the DC motor (12) and the photoelectric encoder (13) are coaxially mounted, the driving wheel (1) is connected to the DC motor (12) through the coupling (11), the photoelectric encoder (13) is mounted on the output shaft end of the DC motor (12), and the driven wheel (5) is driven by the driving wheel (1) to run; Four supports (4) are designed on the side of the housing gantry (21), and guide pulleys (3) are installed on the supports (4). The gap between the probe mounting surfaces (23) on both sides inside the housing gantry (21) and the side of the rail head of the rail (6) is consistent and within 3 mm.

2. The rail array eddy current automatic scanning device according to claim 1, characterized in that: The control device and the wireless communication device are installed in the circuit board compartment (22) and are used to control and send speed instructions. The photoelectric encoder (13) is used to accurately measure the speed and position of the DC motor (12) to achieve closed-loop control of the DC motor (12).

3. The rail array eddy current automatic scanning device according to claim 2, characterized in that: The signal transmission process of the driving device is as follows: a host computer based on LabVIEW sends a start and speed command through a wireless communication device, and a control device receives the command, outputs a PWM wave and controls the DC motor (12) to rotate through the driving device, and a photoelectric encoder (13) outputs a pulse signal which is counted and processed by the control device. When there is a deviation between the actual speed and the set speed, a PID algorithm is used to calculate the adjustment amount according to the size and change trend of the deviation, and then the pulse width of the PWM wave is adjusted.

4. The rail array eddy current automatic scanning device according to claim 1, characterized in that: A probe wiring hole is provided under the circuit board compartment (22); a probe electronic device is provided in the circuit board compartment (22); the array eddy current probe (7) is connected to the probe electronic device via a wire passing through the probe wiring hole; and a sliding cover plate (24) for sealing and disassembling the electronic device is provided on the circuit board compartment (22).

5. The rail array eddy current automatic scanning device according to claim 4, characterized in that: The probe electronic device comprises a drive and detection circuit of the array eddy current probe (7), a motor control circuit, a wireless transmission circuit, and a power supply battery.

6. A detection method for a rail array eddy current automatic scanning device according to any one of claims 1 to 5, characterized in that: The array eddy current probe (7) is made of a flexible printed circuit board and is attached to the probe mounting surface (23). The array eddy current probe (7) comprises 16 flat coils directly processed on the flexible circuit board. Each group of 4 coils is printed in staggered layers to form 4 groups of interchangeable coil layouts, which are respectively used to detect the top surface and two side surfaces of the rail head of the rail (6). The 4 coils are connected as a bridge, and the output voltage thereof is: Where: U O is the bridge output voltage, E is the excitation voltage, is the relative change in impedance of the first coil, is the relative change in impedance of the second coil, is the relative change in impedance of the third coil, is the relative change in impedance of the fourth coil; Since the eddy current formed under a single coil is circular, its response to defects in any direction is consistent, so that defects in any direction can always pass through any of the four coils in sequence, causing the impedance change of the coil group ΔZ i , so when there is a defect in any direction under the coil group, the output voltage of the array eddy current probe (7) is: in: is the relative change in impedance through the defective coil; If there is no defect under the coil, the output voltage is 0; for a rough rail surface, since they are evenly distributed on the surface of the rail (6), the response of each coil is consistent, so the output voltage is 0; the change in the distance between the coil and the rail (6) surface caused by the shaking of the array eddy current probe (7) will also cause the coil impedance to change, but since the shaking direction of the coils in the same group is consistent, the impedance change is also consistent, and its output voltage is still 0.

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