A pipeline inner wall crack detection device and method

Abstract

The application discloses a pipeline inner wall crack detection device and method, and belongs to the technical field of nondestructive testing. The device comprises a robot carrier, a positioning modeling unit, a composite magnetization module, a spraying unit, an imaging unit and a control unit. The robot carrier carries each unit to travel on the inner wall of the pipeline, and the positioning modeling unit identifies the to-be-detected area. The composite magnetization module is integrated with a first magnetization unit for generating a circumferential magnetic field and a second magnetization unit for generating an axial magnetic field, and the control unit realizes omnidirectional magnetization of different orientation cracks by starting the two magnetization units. Liquid medium capable of displaying magnetic marks under light is sprayed during the magnetization process, the imaging unit collects the magnetic mark images and the control unit identifies the crack information. The application solves the problems of insufficient detection rate of horizontal or vertical cracks and large blind area of artificial detection by the single magnetization mode, and effectively improves the detection rate and detection efficiency of full-orientation cracks on the inner wall of the pipeline.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and in particular to a device and method for detecting cracks in the inner wall of a pipeline. Background Technology

[0002] In nuclear power plants, the weld areas and / or heat-affected zones on the inner walls of numerous ferritic steel pipes (such as main steam pipes and heat transfer pipes) may develop microcracks in different directions after long-term operation under high temperature, high pressure, and corrosive environments, seriously threatening nuclear safety. Magnetic particle testing is an effective means of detecting surface and near-surface cracks in such ferromagnetic materials, but its sensitivity depends on the relative relationship between the defect direction and the direction of the magnetizing magnetic field—the detection rate is highest when the two are perpendicular.

[0003] Existing technologies for detecting cracks in the inner walls of pipelines are limited by the pipeline structure and typically employ only one magnetization method. For example, the axial current method (electric current is applied to both ends of the pipeline to generate a circumferential magnetic field) is highly sensitive to transverse cracks perpendicular to the pipeline axis, but less effective for longitudinal cracks parallel to the pipeline axis. Conversely, the coil method (electrifying a coil to generate an axial magnetic field) is sensitive to longitudinal cracks, but has limited detection capability for transverse cracks. This inherent contradiction means that the detection rate of a single magnetization method may have blind spots, making it difficult to meet the high standards required for non-destructive testing of transverse and longitudinal cracks in fields such as nuclear safety. Furthermore, existing technologies also suffer from reliance on manual operation and low detection efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a device and method for detecting cracks in the inner wall of pipes, aiming to solve the problem of how to improve the detection rate and efficiency of cracks in different directions in the inner wall of pipes.

[0005] In a first aspect, embodiments of the present invention provide a pipe inner wall crack detection device, comprising: Robotic carriers used to travel along the inner wall of pipes; A positioning and modeling unit, mounted on the robot carrier, is used to acquire the area to be measured on the inner wall of the pipe, the area to be measured including the weld area and / or the heat-affected zone; A composite magnetization module, installed on the robot carrier, includes a first magnetization unit for applying a circumferential magnetic field and a second magnetization unit for applying an axial magnetic field; A spraying unit, mounted on the robot carrier, is used to spray a liquid medium that can display magnetic traces under light onto the area to be tested during the magnetization process. An imaging unit, mounted on the robot carrier, is used to acquire magnetic trace images of the area to be tested under light illumination; The control unit is connected to the robot carrier, the positioning and modeling unit, the composite magnetization module, the spraying unit, and the imaging unit, respectively. It is used to control the first magnetization unit, the second magnetization unit, and the spraying unit to work according to the area to be tested, and to identify cracks in the inner wall of the pipe according to the magnetic trace image.

[0006] Secondly, embodiments of the present invention provide a method for detecting cracks in the inner wall of a pipe, applied to the pipe inner wall crack detection device described above, the method comprising: The robot carrier is controlled to move along the inner wall of the pipe and is positioned to the area to be measured by the positioning and modeling unit. The first magnetizing unit is controlled to apply a circumferential magnetic field, and the second magnetizing unit is controlled to apply an axial magnetic field, thereby performing circumferential and axial magnetization treatment on the area to be tested; The spraying unit is controlled to spray a liquid medium that can display magnetic traces under light onto the area to be tested during the magnetization process; The imaging unit is controlled to acquire magnetic trace images of the area to be tested after the liquid medium is sprayed. The magnetic trace image is processed for image processing and crack identification, and the location, direction and size information of the crack are output.

[0007] The beneficial effects of this invention are as follows: First, the robot carrier is controlled to move along the inner wall of the pipe. The positioning and modeling unit acquires information about the inner wall of the pipe and identifies features of the area to be tested, guiding and positioning the device to the area to be tested. Next, the first magnetization unit in the composite magnetization module applies a circumferential magnetic field, and the second magnetization unit applies an axial magnetic field, thereby performing circumferential and axial magnetization treatments on the area to be tested sequentially. Magnetization in both directions ensures that both transverse and longitudinal cracks generate sufficiently strong leakage magnetic fields. During magnetization, the spraying unit sprays a liquid medium that can display magnetic traces under light onto the area to be tested. Magnetic powder in the liquid medium accumulates at the crack under the attraction of the leakage magnetic field, forming magnetic traces. After spraying, the imaging unit acquires images of the magnetic traces in the area to be tested under light illumination, recording the shape and location of the magnetic traces. Finally, the acquired magnetic trace images are processed for image processing and crack identification. By analyzing the shape, direction, length, and other features of the magnetic traces, the presence of cracks is determined, and the location, direction, and size information of the cracks are output. Based on this, the embodiments of the present invention achieve fully automated magnetic particle testing of the test area on the inner wall of the pipeline through the collaborative work of each unit, so that both circumferential and axial cracks can be reliably detected, improving the detection rate and efficiency, and reducing the blind spots and dependence on manual testing. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of the pipe inner wall crack detection device provided in an embodiment of the present invention.

[0010] Figure 2 This is a schematic flowchart of a pipe inner wall crack detection method provided in an embodiment of the present invention.

[0011] Explanation of the markings in the image: 1. Robot carrier; 11. Magnetic adsorption track; 2. First magnetization unit; 3. Second magnetization unit; 4. Spraying unit; 5. Imaging unit. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0014] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0015] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0016] Please see Figure 1 , Figure 1 This is a schematic diagram of the pipe inner wall crack detection device provided in an embodiment of the present invention.

[0017] like Figure 1 As shown, to improve the detection rate and efficiency of pipeline inner wall cracks, this invention constructs an integrated pipeline inner wall crack detection device. The device includes: a robot carrier 1, a positioning and modeling unit, a composite magnetization module, a spraying unit 4, an imaging unit 5, and a control unit.

[0018] The robot carrier 1 is designed to travel along the inner wall of the pipe. It has a drive mechanism and moving parts that are adapted to the pipe wall to move the entire device to the target position.

[0019] The positioning and modeling unit is mounted on the robot carrier 1 and is used to acquire the test area of ​​the inner wall of the pipe, including the weld area and / or heat-affected area. The positioning and modeling unit can identify the position of the test area by sensing the geometric shape or material properties of the inner wall of the pipe, and provide spatial coordinates for subsequent magnetization operations.

[0020] The composite magnetization module, mounted on the robot carrier 1, includes a first magnetization unit 2 for applying a circumferential magnetic field and a second magnetization unit 3 for applying an axial magnetic field. According to the principle of magnetic particle inspection, when the crack direction in a ferromagnetic material is approximately perpendicular to the direction of the magnetization magnetic field, the crack generates the strongest leakage magnetic field, resulting in the clearest magnetic trace display. The circumferential magnetic field, because its magnetic field lines surround the pipe axis, has high sensitivity for detecting longitudinal cracks parallel to the pipe axis, while the axial magnetic field, because its magnetic field lines are parallel to the pipe axis, has high sensitivity for detecting transverse cracks perpendicular to the pipe axis. By equipping these two magnetization units, the device can generate two orthogonal magnetization magnetic fields sequentially during a single inspection, thus forming an effective leakage magnetic field for cracks of any orientation, overcoming the limitations of a single magnetization direction.

[0021] The spraying unit 4 is also installed on the robot carrier 1 and is used to spray a liquid medium that can display magnetic traces under light onto the area to be tested during the magnetization process. The liquid medium is a fluorescent magnetic suspension containing magnetic powder, or it can be a magnetic suspension without fluorescent substances. After being sprayed onto the magnetized crack surface, the magnetic powder will accumulate at the leakage magnetic field and form an observable magnetic trace.

[0022] The imaging unit 5 is mounted on the robot carrier 1 and is used to acquire magnetic trace images of the area to be tested under light illumination. When the liquid medium is a fluorescent magnetic suspension containing fluorescent magnetic powder, ultraviolet light is selected for illumination to excite the fluorescent magnetic powder to emit visible fluorescence; when the liquid medium is a magnetic suspension without fluorescent substances, visible light is selected for illumination to directly display the magnetic traces formed by the aggregation of magnetic powder, thereby obtaining a high-contrast magnetic trace display.

[0023] The control unit is connected to the robot carrier 1, the positioning and modeling unit, the composite magnetization module, the spraying unit 4, and the imaging unit 5. After acquiring the location of the area to be measured, it coordinates and controls the first magnetization unit 2 and the second magnetization unit 3 to perform magnetization work, controls the spraying unit 4 to spray the liquid medium at an appropriate time, and controls the imaging unit 5 to collect magnetic trace images after spraying. The control unit also has an image recognition function to enhance and extract features from the magnetic trace images, and identify the existence, location, and morphology of cracks.

[0024] Based on this, this embodiment achieves fully automated magnetic particle inspection of cracks in the inner wall of pipes through the collaborative work of each unit, enabling both circumferential and axial cracks to be reliably detected, improving the detection rate and efficiency, and reducing the blind spots and dependence on manual inspection.

[0025] In one embodiment, the robot carrier 1 integrates a magnetic adsorption track 11 and a robotic arm assembly; the magnetic adsorption track 11 is configured to enable the robot carrier 1 to adhere to the inner wall of the pipe and move along the axial or circumferential direction of the pipe; the robotic arm assembly is connected to at least one of the positioning and modeling unit, the first magnetization unit 2, the second magnetization unit 3, the spraying unit 4, and the imaging unit 5 to drive the corresponding unit to move.

[0026] In this embodiment, the magnetic adsorption track 11 can be composed of multiple track plates embedded with permanent magnet blocks. The track wheel is pressed against the inner wall of the ferrite pipe by means of magnetic force, providing sufficient adsorption force to overcome gravity and motion disturbance. It can move stably even in vertical or inverted pipes, driving it to move forward, backward or rotate around the axis of the pipe.

[0027] In this embodiment, the positioning and modeling unit, the first magnetization unit 2, the second magnetization unit 3, the spraying unit 4, and the imaging unit 5 can be directly mounted on the robot carrier 1 or mounted on the robotic arm assembly. For example, if the first magnetization unit 2 needs to have a motion function to contact the inner wall of the pipe, it can be mounted on the robotic arm assembly; if the second magnetization unit 3 needs to be coil-shaped and does not need to contact the inner wall of the pipe, it can be mounted around the robot carrier 1; if the positioning and modeling unit needs to scan the inner wall of the pipe, it can be mounted on the robotic arm assembly for multi-directional motion scanning. Based on this, each unit can adaptively select its installation position according to its needs. The robotic arm assembly can include at least one multi-axis robotic arm, which drives the corresponding units mounted on it to adjust their position and angle.

[0028] In one embodiment, the positioning modeling unit is also used to obtain the inner diameter of the pipe wall; the control unit is used to control the first magnetization unit 2 and the second magnetization unit 3 to perform magnetization work in sequence when the inner diameter of the pipe is greater than or equal to a preset threshold; the control unit is used to control the second magnetization unit 3 and the first magnetization unit 2 to perform magnetization work in sequence when the inner diameter of the pipe is less than the preset threshold.

[0029] In this embodiment, to improve the adaptability of the detection device to different pipe inner diameters and the magnetization efficiency, the control unit is equipped with the function of adaptively selecting the magnetization sequence based on the pipe inner diameter. In this embodiment, the positioning and modeling unit can acquire the inner diameter of the pipe wall while performing the positioning of the area to be measured. The positioning and modeling unit sends the inner diameter data of the pipe to the control unit in real time. The control unit internally presets a preset threshold for the inner diameter of the pipe (for example, the preset threshold is 268 mm). The control unit compares the acquired actual inner diameter of the pipe with the preset threshold and dynamically decides the working order of the first magnetization unit 2 and the second magnetization unit 3 in the composite magnetization module according to the comparison result. If it is determined that the inner diameter of the pipe is greater than or equal to the preset threshold, the control unit will preferentially select the axial energization mode, that is, first control the first magnetization unit 2 (for example, the unit that generates a circumferential magnetic field by applying axial current through electrodes) to perform magnetization work, and after completing the detection of cracks in a certain direction (such as transverse cracks), control the second magnetization unit 3 (for example, the unit that generates an axial magnetic field through coils) to perform magnetization work to detect cracks in another direction (such as longitudinal cracks). Conversely, if it is determined that the inner diameter of the pipe is less than the preset threshold, the control unit will prioritize the circumferential coil mode, and sequentially control the second magnetization unit 3 to perform magnetization work first, and then control the first magnetization unit 2 to perform magnetization work.

[0030] This adaptive sequence adjustment logic is based on theoretical analysis and experimental verification of the effects of two magnetization methods under different pipe inner diameters: under large pipe inner diameters, the circumferential magnetic field generated by the axial current method is more uniform and effective; while under small pipe inner diameters, the axial magnetic field generated by coil excitation is more likely to achieve high intensity and uniform coverage. The technical effect of this specific implementation is that by introducing an adaptive judgment mechanism for pipe inner diameter and a dynamic adjustment mechanism for magnetization sequence, the detection device can automatically switch to the optimal magnetization strategy for pipes with different inner diameters, avoiding the problems of decreased detection sensitivity or insufficient magnetic field strength that may be caused by using a fixed magnetization sequence. Thus, it can ensure a high detection rate for both transverse and longitudinal cracks across the entire pipe inner diameter range (e.g., Φ200-800mm), greatly expanding the application range of a single device.

[0031] In one embodiment, the positioning modeling unit includes a lidar configured to acquire three-dimensional point cloud data of the inner wall of the pipe to achieve the positioning of the area to be measured and the measurement of the inner diameter of the pipe.

[0032] In this embodiment, as the robot carrier 1 travels along the inner wall of the pipe, the lidar rotates at high speed (e.g., 300 rpm) and emits a laser beam to perform line or area scanning of the pipe's inner wall surface. The lidar receives the light signals reflected from the pipe wall and calculates the precise distance information of each scan point by measuring the time of flight or phase difference. Combined with the real-time pose data of the robot carrier 1 (which can be provided by an encoder or inertial measurement unit), these discrete distance points are integrated into high-density three-dimensional point cloud data, with a scanning accuracy of ±0.1 mm.

[0033] In this embodiment, after receiving the 3D point cloud data, the control unit runs a point cloud processing algorithm. First, it accurately locates the boundary and centerline of the area to be measured by identifying geometric abrupt changes in the point cloud (such as bulges caused by weld reinforcement and texture changes in the heat-affected zone). Second, it accurately calculates the inner diameter of the pipe at the current detection position by performing circle or cylinder fitting on the point cloud data of a complete circle or section of the pipe's inner wall. This lidar has an extremely short modeling time; for example, the modeling time for each meter of pipe does not exceed 30 seconds, enabling real-time modeling and positioning.

[0034] Based on this, this embodiment utilizes LiDAR to acquire high-precision three-dimensional point cloud data, providing a reliable data foundation for the subsequent precise docking of the robot carrier 1, the pose adjustment of the robotic arm, and the selection of the adaptive magnetization mode for the inner diameter of the pipe by the control unit. This avoids the increased system complexity and cost caused by configuring different sensors for different functions, and effectively improves the accuracy of the positioning of the area to be measured and the accuracy of the inner diameter measurement of the pipe.

[0035] In one embodiment, the first magnetization unit 2 includes an electrode assembly configured to form a circumferential magnetic field in the inner wall of the pipe by moving it into contact with the inner wall of the pipe and applying a current flowing along the axial direction of the pipe.

[0036] In this embodiment, the electrode assembly has a retractable actuator (such as the multi-axis robotic arm described above), which extends outward from the composite magnetization module during operation, ensuring the electrode tip is in close contact with the inner wall of the pipe; it retracts when not in operation or when the second magnetization unit 3 is working to prevent interference. Once a reliable electrical contact is established between the electrode and the inner wall of the pipe, the control unit controls the power supply to output DC current to the electrode. The current flows from one electrode into the pipe wall, is conducted along the pipe axis to the other electrode, and flows out, forming a complete current loop. The current flowing along the pipe axis induces a circumferential magnetic field around the pipe axis inside and around the pipe wall. This circumferential magnetic field magnetizes the pipe wall in the circumferential direction, providing high detection sensitivity for transverse cracks perpendicular to the pipe axis.

[0037] This embodiment uses the pipe as a current-carrying conductor to directly generate a circumferential magnetic field. The structure is simple and the magnetization efficiency is high. It is particularly suitable for use inside long-distance pipes, without the need to install large magnetization coils on the outside of the pipe.

[0038] More specifically, the electrode assembly includes at least two spring-loaded electrodes spaced apart along the axial direction of the pipe. Each spring-loaded electrode includes a conductive contact and a constant-force spring, which is used to press the conductive contact against the inner wall of the pipe at a preset contact pressure.

[0039] In this specific embodiment, the electrode assembly includes at least two spring-loaded electrodes spaced apart along the axial direction of the pipe. Each spring-loaded electrode includes a conductive contact and a constant-force spring. One end of the constant-force spring is fixed to the electrode base, and the other end acts on the conductive contact, providing a preset contact pressure to the conductive contact and causing it to continuously press against the inner wall of the pipe. The conductive contact is typically made of a high-conductivity, high-hardness, and wear-resistant alloy material to ensure low contact resistance and good durability when a large current passes through. The contact pressure output by the constant-force spring is essentially constant within a certain compression stroke, which can effectively compensate for changes in contact gap caused by unevenness, ellipticity, or minor vibrations during robot movement, preventing overheating, sparking, or magnetization interruption due to a sudden increase in contact resistance. The preset contact pressure is determined according to the required current-carrying capacity, ensuring stable low-resistance electrical contact during operation without damaging the pipe wall surface. Through the spring-loaded electrodes, the first magnetization unit 2 can achieve rapid and stable electrical connection during dynamic detection, providing a reliable guarantee for the stable application of the circumferential magnetic field, thereby ensuring the consistency and reliability of the transverse crack detection signal.

[0040] In one embodiment, the first magnetization unit 2 applies a current I flowing along the axial direction of the pipe, which satisfies: I = 350 + 0.5 × (D1 - D2); where the unit of current I is amperes, D1 is the measured value of the inner diameter of the pipe, D2 is a preset threshold, and both D1 and D2 are in millimeters. When the formula is calculated, only the values ​​of D1 and D2 are substituted.

[0041] In this embodiment, the formula is derived based on magnetic circuit analysis and experimental verification. Specifically, when the inner diameter of the pipe is greater than the preset threshold D2, the magnetic cross-sectional area of ​​the pipe wall and the perimeter of the magnetic circuit change with the increase of the inner diameter. In order to obtain a circumferential magnetic field strength sufficient to detect microcracks on the inner wall surface of the pipe, the magnetizing current needs to be increased accordingly. The linear relationship coefficient of current with the increase of inner diameter of pipe (0.5) and the reference current (350A) are parameters determined through optimization under the premise of meeting the sensitivity requirements, which can keep the circumferential magnetization effect stable over a wide range of inner diameters of pipes. After obtaining the inner diameter of the pipe, the control unit calculates the target current value according to the formula and outputs a corresponding constant DC current through closed-loop control power supply. This method of dynamically adjusting the current according to the inner diameter of the pipe allows the first magnetizing unit 2 to adapt to pipes with different inner diameters without stopping the machine to replace hardware, ensuring that a suitable circumferential magnetization intensity can be obtained for each detection, thereby ensuring that the detection rate of transverse cracks is not affected by changes in the inner diameter of the pipe.

[0042] In one embodiment, the second magnetization unit 3 includes an inner excitation coil and an outer compensation coil, which are coaxially double-layered; the inner excitation coil is used to generate an axial magnetic field, and the outer compensation coil is used to compensate for magnetic field distortion at the ends or edge regions of the coil.

[0043] In this embodiment, the inner excitation coil is the main component for generating the axial magnetic field. When an excitation current is applied, a magnetic field parallel to the coil axis is generated inside it according to the law of electromagnetic induction. This axial magnetic field is used to magnetize the pipe wall, causing leakage magnetic fields to be generated in the transverse cracks perpendicular to the pipe axis. However, the magnetic field distribution of a single coil in the axial direction will show the characteristics of being strong in the middle and weak at both ends, with the magnetic field lines at the ends diverging outward, resulting in a decrease in magnetic field uniformity. Therefore, an outer compensation coil is added. The outer compensation coil is arranged coaxially with the inner excitation coil and is usually designed as a Helmholtz or gradient compensation structure. When a current with the same phase as or adjustable from the inner coil is applied, the magnetic field at the ends and edges of the active compensation coil decreases, thereby improving the magnetic field uniformity in the axial direction.

[0044] Based on this, in this embodiment, through the coordinated operation of the inner and outer double-layer coils, the second magnetization unit 3 can generate a uniform axial magnetic field within the axial range where the crack is located, ensuring that no matter where the transverse crack is located in the magnetization region, it can be subjected to a basically consistent magnetization effect, thereby generating a stable leakage magnetic field strength and clearly distinguishable magnetic traces, which improves the accuracy and consistency of transverse crack detection.

[0045] In one embodiment, in conjunction with the above-mentioned adaptive control strategy for the inner diameter of the pipe, the axial magnetic field strength B applied by the second magnetization unit 3 satisfies the following formula: B = 1.5 × (D2 / D1)^0.8; where the unit of strength B is Tesla, D2 / D1 is a ratio operation, D1 and D2 use the same length unit and are substituted into the value when the formula is calculated, and 0.8 is the exponent of D2 / D1.

[0046] In this embodiment, the nonlinear correspondence is obtained based on experimental fitting of the magnetization characteristics of samples with different pipe inner diameters. Specifically, when the pipe inner diameter decreases, the magnetic circuit cross-sectional area of ​​the pipe wall decreases. To achieve a magnetization level comparable to that of a larger pipe inner diameter, a stronger excitation magnetic field needs to be generated in space to increase the magnetic flux density in the pipe wall. The exponent 0.8 and the coefficient 1.5 reflect the influence of the pipe inner diameter change on the magnetic field penetration efficiency. Within the range where D1 is less than D2, the axial magnetic field strength can be increased according to the formula to ensure sufficient magnetization of the pipe wall with a small inner diameter. After determining the pipe inner diameter, the control unit calculates the required target value of the magnetic field strength according to this formula and indirectly adjusts the magnetic field strength by adjusting the excitation current of the second magnetization unit 3. This adaptive adjustment of the magnetic field strength allows the second magnetization unit 3 to still excite an effective axial magnetization field for different pipe inner diameters, especially smaller pipe inner diameters, thereby ensuring the detection sensitivity of longitudinal cracks. This, combined with the adaptive current of the first magnetization unit 2, forms a cooperative mechanism to achieve the pipe inner diameter coverage capability for omnidirectional crack detection.

[0047] like Figure 2 As shown, this embodiment of the invention also provides a method for detecting cracks in the inner wall of a pipe, applied to the aforementioned pipe inner wall crack detection device, the method comprising: S100: Control the robot carrier 1 to move along the inner wall of the pipe and position it to the area to be measured through the positioning and modeling unit; S200: Control the first magnetization unit 2 to apply a circumferential magnetic field and control the second magnetization unit 3 to apply an axial magnetic field, thereby performing circumferential and axial magnetization treatment on the area to be measured. S300, the spraying unit 4 sprays a liquid medium that can display magnetic traces under light onto the area to be tested during the magnetization process; S400, the imaging unit 5 controls the acquisition of magnetic trace images of the area to be measured after spraying the liquid medium; S500 performs image processing and crack identification on the magnetic trace image, and outputs the location, direction and size information of the crack.

[0048] In steps S100-S500, the scheme is implemented based on the aforementioned device comprising a robot carrier 1, a positioning and modeling unit, a composite magnetization module, a spraying unit 4, an imaging unit 5, and a control unit. First, the robot carrier 1 is controlled to move along the inner wall of the pipe. The positioning and modeling unit acquires information about the inner wall of the pipe and identifies crack features, guiding and positioning the device to the area to be tested. Next, the first magnetization unit 2 in the composite magnetization module applies a circumferential magnetic field, and the second magnetization unit 3 applies an axial magnetic field, thereby performing circumferential and axial magnetization treatments sequentially in the area to be tested. Magnetization in both directions ensures that both transverse and longitudinal cracks generate sufficiently strong leakage magnetic fields. During magnetization, the spraying unit 4 sprays a liquid medium capable of displaying magnetic traces under light onto the area to be tested. Magnetic powder in the liquid medium accumulates at the cracks under the attraction of the leakage magnetic field, forming magnetic traces. After spraying, the imaging unit 5 acquires images of the magnetic traces in the area to be tested under light illumination, recording the shape and position of the magnetic traces. Finally, the acquired magnetic trace images are processed and cracks are identified. By analyzing the shape, direction, length and other features of the magnetic traces, the presence of cracks is determined, and the location, direction and size of the cracks are output.

[0049] Based on this, this method achieves fully automated detection through automatic navigation and positioning, composite magnetization, and programmed spraying imaging, effectively eliminating blind spots and subjective errors caused by manual operation. It can comprehensively and efficiently detect various orientation cracks on the inner wall of pipelines, improving detection speed and objectivity of results.

[0050] In one embodiment, steps S100 to S500 are executed by the control unit in a unified timing sequence as follows: S100 Positioning Stage: Control the robot carrier 1 to move along the inner wall of the pipe at a preset speed. The lidar in the positioning modeling unit acquires the three-dimensional point cloud data of the inner wall of the pipe in real time, identifies the area to be measured, and measures the inner diameter D1 of the pipe. The control unit controls the robot carrier 1 to stop precisely according to the three-dimensional point cloud data, so that the whole device reaches the area to be measured. S200 Magnetization Stage: The control unit compares the inner diameter D1 of the pipe with the preset threshold D2 to determine the working order of the first magnetization unit 2 and the second magnetization unit 3, and calculates the magnetization current or axial magnetic field strength according to I = 350 + 0.5 × (D1 - D2) or B = 1.5 × (D2 / D1)^0.8 respectively; at the beginning of magnetization, the current is applied with a preset gradient (e.g., 50 A / s) or pulse excitation is started, and after the magnetization magnetic field stabilizes, it is maintained for a preset duration (e.g., 3-5 s) so that the area to be measured is fully magnetized; S300 Spraying Stage: After the magnetized magnetic field stabilizes and is delayed for a first time (e.g., 100ms), the control unit controls the spraying unit 4 to spray a liquid medium that can display magnetic traces under light onto the area to be tested during the stable maintenance of magnetization; delayed spraying can avoid the interference of magnetic field fluctuations during the magnetization start-up stage on the distribution of liquid medium and the formation of magnetic traces; S400 Imaging Stage: After spraying is completed, a second time delay (e.g., 300ms) is achieved, and the control unit controls the imaging unit 5 to acquire magnetic trace images of the area to be tested under light illumination; delayed imaging can avoid interference from liquid surface reflection on the quality of the magnetic trace images; S500 identification stage: The control unit performs image processing and crack identification on the magnetic trace images acquired by S400, and outputs the location, direction and size information of the cracks; for areas identified as suspicious, the control unit can control the spraying unit 4 and imaging unit 5 to automatically re-inspect the area.

[0051] For example, when the positioning and modeling unit measures the inner diameter of the pipe as D1 = 600 mm, which is greater than the preset threshold D2 = 268 mm, the control unit selects the axial energization priority mode: In S200, the spring-loaded electrode of the first magnetization unit 2 is first extended to press against the inner wall of the pipe with a preset contact pressure and confirm that the contact resistance meets the requirements. The target current is calculated as I = 350 + 0.5 × (D1 - D2) to be approximately 516 A. A DC current flowing along the axial direction of the pipe is applied with a preset gradient (e.g., 50 A / s) and maintained stably for 3-5 seconds to form a circumferential magnetic field in the inner wall of the pipe, which forms a strong leakage magnetic field for the transverse crack. In S300, after the magnetic field stabilizes, the liquid medium is sprayed with a delay as described above. In S400, after the spraying is completed, the magnetic trace image is acquired with a delay. After completion, the second magnetization unit 3 is controlled to apply an axial magnetic field to supplement the magnetization of the longitudinal crack, and the above spraying and imaging steps are repeated.

[0052] For example, when the positioning and modeling unit measures the inner diameter of the pipe as D1 = 200 mm, which is less than the preset threshold D2 = 268 mm, the control unit selects the circumferential coil priority mode: In S200, the electrodes of the first magnetization unit 2 are first ensured to retract, and then the second magnetization unit 3 is controlled to apply pulse excitation. The target axial magnetic field strength is calculated to be approximately 1.90 T according to B = 1.5 × (D2 / D1)^0.8, forming an axial magnetic field in the inner wall of the pipe, which forms a strong leakage magnetic field for the longitudinal crack; In S300, after the magnetic field stabilizes, the liquid medium is sprayed with the above-mentioned delay; In S400, after the spraying is completed, the magnetic trace image is acquired with a delay; After completion, the first magnetization unit 2 applies a circumferential magnetic field to supplement the magnetization of the transverse crack, and the above spraying and imaging steps are repeated.

[0053] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described apparatus and unit can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A device for detecting cracks in the inner wall of a pipe, characterized in that, include: Robotic carriers used to travel along the inner wall of pipes; A positioning and modeling unit, mounted on the robot carrier, is used to acquire the area to be measured on the inner wall of the pipe; wherein the area to be measured includes the weld area and / or the heat-affected zone; A composite magnetization module, installed on the robot carrier, includes a first magnetization unit for applying a circumferential magnetic field and a second magnetization unit for applying an axial magnetic field; A spraying unit, mounted on the robot carrier, is used to spray a liquid medium that can display magnetic traces under light onto the area to be tested during the magnetization process. An imaging unit, mounted on the robot carrier, is used to acquire magnetic trace images of the area to be tested under light illumination; The control unit is connected to the robot carrier, the positioning and modeling unit, the composite magnetization module, the spraying unit, and the imaging unit, respectively. It is used to control the operation of the first magnetization unit, the second magnetization unit, and the spraying unit according to the area to be tested, and to identify cracks in the inner wall of the pipe according to the magnetic trace image.

2. The pipe inner wall crack detection device according to claim 1, characterized in that, The robot carrier integrates magnetically adsorbed tracks and a robotic arm assembly. The magnetic adsorption track is configured to enable the robot carrier to adhere to the inner wall of the pipe and move along the axial or circumferential direction of the pipe. The robotic arm assembly is connected to at least one of the positioning and modeling unit, the first magnetization unit, the second magnetization unit, the spraying unit, and the imaging unit to drive the corresponding unit to move.

3. The pipe inner wall crack detection device according to claim 1, characterized in that, The positioning modeling unit is also used to obtain the inner diameter of the pipe; The control unit is used to sequentially control the first magnetization unit and the second magnetization unit to perform magnetization work when the inner diameter of the pipe is greater than or equal to a preset threshold. The control unit is used to sequentially control the second magnetization unit and the first magnetization unit to perform magnetization work when the inner diameter of the pipe is less than a preset threshold.

4. The pipe inner wall crack detection device according to any one of claims 1 to 3, characterized in that, The positioning and modeling unit includes a lidar, which is configured to acquire three-dimensional point cloud data of the inner wall of the pipe to achieve the positioning of the area to be measured and the measurement of the inner diameter of the pipe.

5. The pipe inner wall crack detection device according to any one of claims 1 to 3, characterized in that, The first magnetization unit includes an electrode assembly configured to generate a circumferential magnetic field in the inner wall of the pipe by moving it into contact with the inner wall of the pipe and applying a current flowing along the axial direction of the pipe.

6. The pipe inner wall crack detection device according to claim 5, characterized in that, The electrode assembly includes at least two spring-loaded electrodes spaced apart along the axial direction of the pipe. Each spring-loaded electrode includes a conductive contact and a constant-force spring. The constant-force spring is used to press the conductive contact against the inner wall of the pipe with a preset contact pressure.

7. The pipe inner wall crack detection device according to claim 5, characterized in that, The first magnetizing unit applies a current I flowing along the axial direction of the pipe, which satisfies the following: I = 350 + 0.5 × (D1 - D2); where the unit of current I is amperes, D1 is the measured value of the inner diameter of the pipe, D2 is a preset threshold, and both D1 and D2 are in millimeters. When calculating the formula, only the values ​​of D1 and D2 are substituted.

8. The pipe inner wall crack detection device according to any one of claims 1 to 3, characterized in that, The second magnetization unit includes an inner excitation coil and an outer compensation coil, both coaxially double-layered. The inner excitation coil is used to generate an axial magnetic field, and the outer compensation coil is used to compensate for magnetic field distortion at the ends or edges of the coil.

9. The pipe inner wall crack detection device according to claim 7, characterized in that, The axial magnetic field strength B applied by the second magnetization unit satisfies: B=1.5×(D2 / D1)^0.8; where the unit of strength B is Tesla, and D2 / D1 is a ratio operation. When performing the formula operation, D1 and D2 use the same length unit and are substituted into the value.

10. A method for detecting cracks in the inner wall of a pipe, applied to the pipe inner wall crack detection device as described in claim 1, characterized in that, The method includes: The robot carrier is controlled to move along the inner wall of the pipe and is positioned to the area to be measured by the positioning and modeling unit. The first magnetizing unit is controlled to apply a circumferential magnetic field, and the second magnetizing unit is controlled to apply an axial magnetic field, thereby performing circumferential and axial magnetization treatment on the area to be tested; The spraying unit is controlled to spray a liquid medium that can display magnetic traces under light onto the area to be tested during the magnetization process; The imaging unit is controlled to acquire magnetic trace images of the area to be tested after the liquid medium is sprayed. The magnetic trace image is processed for image processing and crack identification, and the location, direction and size information of the crack are output.

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