A device and method for detecting a direct current through a piston rod

Abstract

This invention discloses a piston rod DC-powered detection device and method, relating to the field of non-destructive testing technology. The device includes a detection component for detecting axial and circumferential damage to the piston rod, and a driving component for driving the detection component and the piston rod to perform axial relative motion. The driving component is connected to the detection component. This device solves the problem that existing optical and electromagnetic detection methods cannot meet the flaw detection requirements of piston rods in gate hoists when they are covered with oil and have a metal coating, and require online detection. It features a simple and easy-to-use structure, requires no large equipment, and can perform comprehensive and accurate online detection of piston rod damage.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and more specifically, to a device and method for detecting the conduction of direct current through a piston rod. Background Technology

[0002] Hydraulic gate hoists are crucial mechanical devices in water conservancy projects, used to open and close gates. The piston rod is one of the main components affecting the service life of the hydraulic gate hoist and directly impacts its operational status. Under long-term pressure, corrosion or cracks can easily develop on the piston rod surface, causing oil leaks during operation and potential jamming, preventing the gate from opening or closing properly and threatening the safety of the hydropower station. Therefore, regular surface defect inspection of the hydraulic gate hoist piston rod is necessary.

[0003] Currently, the non-destructive testing methods available for detecting surface defects in piston rods fall into two main categories: optical testing and electromagnetic testing. Electromagnetic testing commonly employs eddy current testing and magnetic flux leakage testing. Each of these three testing methods has its advantages, but for the technical field of piston rods in gate opening and closing mechanisms described in this application, the following technical problems remain insurmountable:

[0004] 1. Optical inspection has high requirements for the surface condition of the piston rod; however, in the service of gate hoists, the piston rod works in a harsh environment with silt, oil and water for a long time, which makes its surface often covered with mud and oil. The surface defects of the piston rod are covered by mud or oil, and optical inspection cannot penetrate them, which will lead to missed detection.

[0005] 2. Eddy current testing method uses a coil placed above the piston rod surface to excite an alternating electromagnetic field, thereby generating eddy currents in the piston rod, and achieves flaw detection by disturbing the eddy currents through defects; however, the piston rod surface is usually coated with a metal coating, which causes the excited eddy currents to concentrate in the coating and cannot penetrate into the piston rod, greatly reducing the detection accuracy.

[0006] 3. In magnetic flux leakage detection, the piston rod is magnetized to near saturation using a magnetizer, and the magnetic flux leakage field generated by the defect is picked up by a magnetic sensor. For example, patent application number "CN95212309.6" discloses a magnetic flux leakage flaw detector for steel pipes, which achieves flaw detection by saturating the pipe under test and then detecting the magnetic flux leakage state. However, a large magnetizer is often required to magnetize the pipe under test to near saturation, making it more suitable for independent testing after disassembly. In this application, the piston rod is located inside the equipment and cannot be easily removed from the gate hoist for independent testing. If disassembly is required, the entire hydropower unit must be disassembled and repaired. Therefore, the piston rod in this application needs to be tested online, and a large magnetizer cannot be used for saturation magnetization.

[0007] In summary, existing optical inspection methods and electromagnetic non-destructive testing methods cannot fully meet the requirements for online, efficient, and high-precision inspection of piston rod surface defects. Therefore, it is necessary to design a piston rod DC current inspection device and method to meet the flaw detection requirements of the piston rod in this application under the conditions of oil stains on the surface, metal coating on the surface, and the need for online inspection. Summary of the Invention

[0008] To overcome or at least partially solve the above problems, embodiments of the present invention provide a piston rod DC current detection device and method. This solution solves the problem that existing optical and electromagnetic detection methods cannot meet the flaw detection requirements of piston rods of gate hoists when they are covered with oil stains, have a metal coating on their surface, and require online detection. It has the characteristics of simple structure and easy use, no need for large equipment, and can perform comprehensive and accurate online detection of piston rod damage.

[0009] To achieve the above-mentioned technical effects, the technical solution provided by the present invention is as follows:

[0010] A piston rod DC current detection device includes a detection component and a drive component; the detection component includes a DC excitation source and a detection probe, the detection probe is electrically connected to an A / D acquisition card and a processor, and the DC excitation source is electrically connected to the piston rod to be detected, thereby energizing the piston rod along the axial direction.

[0011] Preferably, the signal output terminal of the detection probe is electrically connected to the signal input terminal of the amplifier, the signal output terminal of the amplifier is electrically connected to the signal input terminal of the filter, and the filter is electrically connected to the A / D acquisition card and the processor.

[0012] Furthermore, an amplifier, a filter, and an A / D acquisition card are electrically connected in sequence between the detection probe and the processor to further process the detection signal before sending it to the processor for analysis.

[0013] Preferably, the detection probe is connected to the drive assembly, which includes a rotating mechanism and a traveling mechanism. The rotating mechanism drives the detection probe and the piston rod to move circumferentially relative to each other to detect axial damage to the piston rod; the traveling mechanism drives the detection probe and the piston rod to move axially relative to each other to detect circumferential damage to the piston rod.

[0014] Furthermore, the rotating mechanism is used to generate circumferential relative motion between the detection probe and the piston rod; the traveling mechanism is used to generate axial relative motion between the detection probe and the piston rod; this motion process can be applied to either the detection probe or the piston rod.

[0015] Preferably, the detection probe includes a Hall element, an AMR sensor, a GMR sensor, or a TMR sensor.

[0016] Preferably, the DC excitation source is an adjustable DC power supply.

[0017] Preferably, the detection probe is positioned directly opposite the piston rod surface.

[0018] Preferably, the magnetic sensing direction of the detection probe is parallel to the radial direction of the piston rod.

[0019] Preferably, the method for detecting DC current flowing through a piston rod as described above includes the following steps:

[0020] S1, apply DC excitation to the piston rod to be tested along the axial direction through a DC excitation source, and position the detection probe in the detection assembly facing the surface of the piston rod;

[0021] S2, the detection probe and piston rod are driven to move relative to each other in the circumferential direction by the rotation mechanism in the drive assembly, and the axial damage of the piston rod is detected by the detection probe;

[0022] S3, the detection probe and the piston rod are driven to move relative to each other along the axial direction by the traveling mechanism in the drive assembly, and the circumferential damage of the piston rod is detected by the detection probe;

[0023] S4 processes and transmits the data detected by the detection probe through the amplifier, filter, and A / D acquisition card in the detection component. The detection signal is then sent to the processor in the detection component for analysis and processing to obtain the piston rod flaw detection information.

[0024] Preferably, in step S1, after the piston rod under test is subjected to DC excitation along the axial direction, a current is applied along the axial direction inside the piston rod, generating a circumferential magnetic field inside and outside the piston rod.

[0025] Preferably, in steps S2-S3, the method for detecting axial and circumferential damage to the piston rod using a detection probe is as follows:

[0026] S201, the circumferential magnetic field inside the piston rod leaks into the air through the axial damage, forming a leakage magnetic field. By detecting the circumferential movement of the detection probe, the leakage magnetic field signal generated by the axial damage after the piston rod is magnetized is picked up, thus realizing the detection of axial damage to the piston rod.

[0027] S301, circumferential damage disturbs the current inside the piston rod, causing a non-axial current density component to be generated. The non-axial current density component causes changes in the direction and magnitude of the magnetic field outside the piston rod. By detecting the axial movement of the probe, the magnetic field variation signal caused by the disturbance of the current inside the piston rod due to the circumferential damage is picked up.

[0028] The present invention has the following beneficial effects:

[0029] This invention provides a piston rod DC current detection device and method. When it is necessary to detect damage to a target piston rod, the piston rod is first excited axially by a detection component. Then, the detection component moves circumferentially relative to the piston rod through a drive component to detect axial damage. Similarly, the detection component moves circumferentially relative to the piston rod through the drive component to detect circumferential damage. During detection, the detection component analyzes and processes the detected signals to obtain piston rod flaw detection information, achieving comprehensive, accurate, and effective damage detection of the piston rod. This device has a simple structure, requires no magnetizer, and is suitable for high-speed, automated piston rod detection. It uses an axial DC current method, which can simultaneously detect axial and circumferential damage. Furthermore, this invention uses an axial DC current method, eliminating the skin effect and allowing simultaneous detection of internal and external damage. The method is simple to operate, the overall equipment occupies little space, and can be used for online detection of piston rods in gate hoists without disassembling the piston rod. It can adapt to conditions where the piston rod surface is covered with oil and is not affected by the metal coating on the piston rod surface. Overall, the detection efficiency is high, and the detection effect is accurate. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the detection method of the present invention;

[0031] Figure 2 This is a schematic diagram of a piston rod DC current detection device according to an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram illustrating the DC current detection principle of the piston rod in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of axial damage detection in an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of the axial damage magnetic field distribution in an embodiment of the present invention;

[0035] Figure 6 This is a schematic diagram of circumferential damage detection in an embodiment of the present invention;

[0036] Figure 7 This is a schematic diagram of the circumferential magnetic field distribution in an embodiment of the present invention;

[0037] Figure 8 This is a schematic diagram of the drive mechanism in Embodiment 3 of the present invention;

[0038] Figure 9 This is a front view schematic diagram of the driving mechanism in Embodiment 3 of the present invention;

[0039] Figure 10 This is a cross-sectional schematic diagram of the drive mechanism in Embodiment 3 of the present invention;

[0040] In the attached diagram: 1. Piston rod; 2. DC excitation source; 3. Detection probe; 4. Amplifier; 5. Filter; 6. A / D acquisition card; 7. Processor; 8. Rotating mechanism; 9. Traveling mechanism; 10. Base; 11. Electric slide rail; 12. Slider; 13. Clamp; 14. Support ring; 15. Gear ring; 16. Transmission component; 17. Axial damage; 18. Circumferential damage.

[0041] Figure 2 The direction of the middle arrow indicates the direction of the current in the DC excitation source;

[0042] Figure 3 The direction of the middle arrow indicates the direction of direct current;

[0043] Figure 4 The direction of the middle arrow indicates the direction of magnetic sensitivity. Detailed Implementation

[0044] Example 1:

[0045] like Figures 1-3 As shown, a DC current detection device for a piston rod 1 includes a detection component and a drive component. The detection component includes a DC excitation source 2 and a detection probe 3. The detection probe 3 is electrically connected to an A / D acquisition card 6 and a processor 7. The DC excitation source 2 is electrically connected to the piston rod 1 to be tested, and excites the piston rod 1 along the axial direction.

[0046] Preferably, the signal output terminal of the detection probe 3 is electrically connected to the signal input terminal of the amplifier 4, and the signal output terminal of the amplifier 4 is electrically connected to the signal input terminal of the filter 5; the filter 5 is electrically connected to the A / D acquisition card 6 and the processor 7.

[0047] Furthermore, an amplifier 4, a filter 5, and an A / D acquisition card 6 are electrically connected in sequence between the detection probe 3 and the processor 7 to further process the detection signal before sending it to the processor 7 for analysis.

[0048] Preferably, the detection probe 3 is connected to the drive assembly, which includes a rotating mechanism 8 and a traveling mechanism 9. The rotating mechanism 8 drives the detection probe 3 to move circumferentially relative to the piston rod 1, detecting axial damage 17 on the piston rod 1; the traveling mechanism 9 drives the detection probe 3 to move axially relative to the piston rod 1, detecting circumferential damage 18 on the piston rod 1.

[0049] Furthermore, the rotating mechanism 8 is used to generate circumferential relative motion between the detection probe 3 and the piston rod 1; the traveling mechanism 9 is used to generate axial relative motion between the detection probe 3 and the piston rod 1; this motion process can be applied to either the detection probe 3 or the piston rod 1.

[0050] Preferably, the detection probe 3 includes a Hall element, an AMR sensor, a GMR sensor, or a TMR sensor, and the appropriate sensing element can be selected for data detection and acquisition based on actual needs.

[0051] Preferably, the DC excitation source 2 is an adjustable DC power supply, which can provide excitation power of different sizes to meet different needs.

[0052] Preferably, the detection probe 3 is positioned directly opposite the surface of the piston rod 1.

[0053] Preferably, the magnetic sensing direction of the detection probe 3 is parallel to the radial direction of the piston rod 1.

[0054] Preferably, the method for detecting DC current applied to the piston rod 1 as described above includes the following steps:

[0055] S1, DC excitation is applied to the piston rod 1 to be tested along the axial direction through DC excitation source 2, and the detection probe 3 in the detection assembly is positioned facing the surface of the piston rod 1;

[0056] S2, the detection probe 3 and the piston rod 1 are driven to move relative to each other in the circumferential direction by the rotation mechanism 8 in the drive assembly, and the axial damage 17 of the piston rod 1 is detected by the detection probe 3;

[0057] S3, the travel mechanism 9 in the drive assembly drives the detection probe 3 and the piston rod 1 to move relative to each other along the axial direction, and the detection probe 3 detects the circumferential damage 18 of the piston rod 1;

[0058] S4, the data detected by the detection probe 3 is processed and transmitted through the amplifier 4, filter 5 and A / D acquisition card 6 in the detection component, and the detection signal is sent to the processor 7 in the detection component for analysis and processing to obtain the flaw detection information of the piston rod 1.

[0059] Preferably, in step S1, after the piston rod 1 under test is subjected to DC excitation along the axial direction, a current flows along the axial direction inside the piston rod 1, generating a circumferential magnetic field inside and outside the piston rod 1.

[0060] Preferably, in steps S2-S3, the method for detecting axial damage 17 and circumferential damage 18 of the piston rod 1 using the detection probe 3 is as follows:

[0061] S201, the circumferential magnetic field inside the piston rod 1 leaks into the air through the axial wound 17 to form a leakage magnetic field. By moving the detection probe 3 in the circumferential direction, the leakage magnetic field signal generated by the axial wound 17 after the piston rod 1 is magnetized is picked up, so as to realize the detection of the axial wound 17 of the piston rod 1.

[0062] S301, the circumferential injury 18 disturbs the current inside the piston rod 1, causing a non-axial current density component to be generated in the current inside the piston rod 1. The non-axial current density component causes the direction and magnitude of the external magnetic field of the piston rod 1 to change. By detecting the axial movement of the detection probe 3, the magnetic field variation signal generated by the disturbance of the current inside the piston rod 1 due to the circumferential injury 18 is picked up.

[0063] Example 2:

[0064] The working principle of the DC current detection device for piston rod 1 described above is as follows:

[0065] When flaw detection is required on the target piston rod 1, the piston rod 1 is first excited axially by the DC excitation source 2 in the detection assembly. Then, the detection probe 3 in the detection assembly moves circumferentially relative to the piston rod 1 through the rotation mechanism 8 in the drive assembly to detect axial flaws 17 on the piston rod 1. The detection probe 3 in the detection assembly also moves axially relative to the piston rod 1 through the travel mechanism 9 in the drive assembly to detect circumferential flaws 18 on the piston rod 1. During detection, the detection probe 3 in the detection assembly transmits the detected signal to the amplifier 4 for amplification, then filters it through the filter 5, and finally sends the signal to the processor 7 in the detection assembly through the A / D acquisition card 6 for analysis and processing, thereby obtaining the flaw detection information of the piston rod 1, achieving comprehensive, accurate, and effective flaw detection of the piston rod 1. The aforementioned flaw detection information of the piston rod 1 includes axial flaw 17 and axial flaw 18 information; the specific detection principle is as follows:

[0066] like Figures 4-5 As shown, the magnetic sensing direction of the detection probe 3 is parallel to the radial direction of the piston rod 1, and it senses the change in the normal magnetic field component. The axial damage 17 is detected by the detection probe 3 picking up the leakage magnetic field signal generated by the axial damage 17 after the piston rod 1 is magnetized. The circumferential magnetic field inside the piston rod 1 leaks into the air through the axial damage 17 to form a leakage magnetic field. By moving the detection probe 3 circumferentially, the leakage magnetic field signal generated by the axial damage 17 after the piston rod 1 is magnetized is picked up, thus realizing the detection of the axial damage 17 of the piston rod 1.

[0067] like Figures 6-7 As shown, the circumferential defect 18 is detected by the detection probe 3 picking up the magnetic field variation signal caused by the internal current disturbance of the piston rod 1. The circumferential defect 18 disturbs the internal current of the piston rod 1, causing a non-axial current density component. This non-axial current density component causes changes in the direction and magnitude of the external magnetic field of the piston rod 1. When there is no defect, the current j0 flows uniformly inside the piston rod 1, generating an external magnetic field. B When a circumferential defect (18) exists, the current distribution becomes uneven, causing distortion of the external magnetic field. BBy detecting the axial movement of the probe 3, the magnetic field variation signal generated by the disturbance of the circumferential damage 18 in the current inside the piston rod 1 is picked up, thereby realizing the detection of the circumferential damage 18 in the piston rod 1.

[0068] When piston rod 1 is energized, the current inside piston rod 1 flows axially, generating a circumferential magnetic field inside and outside piston rod 1. For axial damage 17, its direction is the same as the current direction, causing almost no disturbance to the current. However, the magnetic field inside piston rod 1 is circumferential, and this internal magnetic field will leak into the air through axial damage 17, essentially similar to magnetic leakage detection, which is detected by the circumferential movement of a magnetic sensor. For circumferential damage 18, it has almost no effect on the internal magnetic field and there is almost no magnetic leakage. However, circumferential damage 18 causes a large disturbance to the current inside piston rod 1. The current near circumferential damage 18 will generate a non-axial current density component. Therefore, the non-axial current density component generated by these disturbances will cause changes in the direction and magnitude of the external magnetic field of piston rod 1, which is detected by the axial movement of a magnetic sensor. This invention uses the axial direct current method, which can simultaneously detect axial damage 17 and circumferential damage 18. Moreover, this invention uses the axial direct current method, which does not have the skin effect and can simultaneously detect internal and external damage.

[0069] Example 3:

[0070] Preferably, such as Figures 8-10 As shown, the structure of the drive mechanism is as follows:

[0071] The drive mechanism includes a rotating mechanism 8 and a traveling mechanism 9; the traveling mechanism 9 includes a base 10, and clamps 13 are connected to both ends of the upper surface of the base 10. The clamps 13 are ring structures composed of two separate semi-circular rings. The two separate semi-circular rings are connected by bolts and tightly held at both ends of the outer surface of the piston rod 1; an electric slide rail 11 is connected to the upper surface of the base 10, and the rotating mechanism 8 is connected to the upper surface of the slider 12 of the electric slide rail 11.

[0072] Furthermore, the rotating mechanism 8 includes a support ring 14, which is connected to the upper surface of the slider 12; the center of the support ring 14 coincides with the axis of the piston rod 1; an annular groove is provided on one side surface of the support ring 14, and a toothed ring 15 is slidably connected in the annular groove, and the detection probe 3 is connected to the inner wall of the toothed ring 15, facing the piston rod 1.

[0073] Furthermore, the rotating mechanism 8 includes a transmission component 16 connected to the upper surface of the slider 12. The transmission component 16 includes a motor and a gear connected to the end of the motor. The gear meshes with the gear ring 15, driving the gear ring 15 to rotate along the annular groove, thereby causing the detection probe 3 to rotate around the piston rod 1.

[0074] In use, the circumferential and axial movements of the detection probe 3 can be achieved through the cooperation of the electric slide rail 11 and the transmission component 16. The clamps 13 at both ends of the device are detachable and can be separated. The detection probe 3 can move circumferentially and axially on its own, which can meet the requirements of online operation where the piston rod 1 cannot be disassembled or rotated.

[0075] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The embodiments and features described in these embodiments can be arbitrarily combined without conflict. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method of detecting a piston rod passage-through direct current detection device, characterized by: The device comprises a detection assembly and a driving assembly; the detection assembly comprises a direct current excitation source (2) and a detection probe (3), the detection probe (3) is electrically connected with an A / D acquisition card (6) and a processor (7), the direct current excitation source (2) is electrically connected with a piston rod (1) to be detected to excite the piston rod in an axial direction; a signal output end of the detection probe (3) is electrically connected with a signal input end of an amplifier (4), a signal output end of the amplifier (4) is electrically connected with a signal input end of a filter (5); the filter (5) is electrically connected with the A / D acquisition card (6) and the processor (7); the detection probe (3) is connected with the driving assembly, the driving assembly comprises a rotating mechanism (8) and a traveling mechanism (9), the rotating mechanism (8) drives the detection probe (3) to make a circumferential relative motion with the piston rod (1) to detect an axial damage of the piston rod (1); the traveling mechanism (9) drives the detection probe (3) to make an axial relative motion with the piston rod (1) to detect a circumferential damage of the piston rod (1); the detection method comprises the following steps: S1, loading a direct current excitation on the piston rod (1) to be detected in an axial direction through the direct current excitation source (2), and making the detection probe (3) in the detection assembly face the surface of the piston rod (1); S2, driving the detection probe (3) to make a relative motion with the piston rod (1) in a circumferential direction through the rotating mechanism (8) in the driving assembly, and detecting the axial damage of the piston rod (1) through the detection probe (3); S3, driving the detection probe (3) to make a relative motion with the piston rod (1) in an axial direction through the traveling mechanism (9) in the driving assembly, and detecting the circumferential damage of the piston rod (1) through the detection probe (3); S4, processing and transmitting the data detected by the detection probe (3) through the amplifier (4), the filter (5) and the A / D acquisition card (6) in the detection assembly, sending the detection signal to the processor (7) in the detection assembly for analysis and processing to obtain the damage information of the piston rod (1); The method for detecting the axial damage and the circumferential damage of the piston rod (1) through the detection probe (3) is as follows: S201, the circumferential magnetic field in the piston rod (1) leaks to the air to form a magnetic leakage field through the axial damage, the detection probe (3) moves in a circumferential direction to pick up the magnetic leakage field signal generated by the axial damage of the piston rod (1) after being magnetized, and the axial damage detection of the piston rod is realized; S301, the circumferential damage disturbs the current in the piston rod (1) to generate a non-axial current density component, the non-axial current density component changes the direction and the size of the external magnetic field of the piston rod (1), the detection probe (3) moves in an axial direction to pick up the magnetic field variation signal generated by the disturbance of the current in the piston rod (1) due to the circumferential damage.

2. The method of claim 1, wherein: The detection probe (3) comprises a Hall element, an AMR sensor, a GMR sensor or a TMR sensor.

3. The method of claim 1, wherein: The direct current excitation source (2) is an adjustable direct current power supply.

4. The method of claim 1, wherein: The detection probe (3) is arranged to face the surface of the piston rod (1).

5. The method of claim 1, wherein: The magnetic sensitive direction of the detection probe (3) is parallel to the radial direction of the piston rod (1).

6. The method of claim 1, wherein: In step S1, the piston rod (1) to be inspected is loaded with a direct current excitation in the axial direction, which generates a circumferential magnetic field inside and outside the piston rod (1) in the axial direction.

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