ACFM alternating current electromagnetic field detection device and method

Abstract

The invention relates to the technical field of pipeline detection, in particular to an ACFM alternating current electromagnetic field detection device and method. The detection device comprises a machine shell, a fixing frame, a transmission mechanism, a sliding frame, a damping assembly, a pipeline cleaning assembly and a transmission assembly, a swing arm A and a swing arm B are rotationally arranged in a guide groove of the machine shell and rotationally connected with the same mounting frame, and an exciting coil and a sensor are arranged on the mounting frame; the fixing frame is arranged in the machine shell, and a plurality of bevel gears and a driving assembly A for driving the bevel gears to rotate are rotationally arranged on the fixing frame; the transmission mechanism is in transmission connection with the bevel gear and the rotating shaft A; a driving assembly B for driving the sliding frame to slide is arranged on the fixed frame; the two ends of the damping assembly are rotationally connected with the sliding frame and the swing arm B on the corresponding side correspondingly. The pipeline cleaning assembly is rotationally arranged on the machine shell. The transmission assembly is in transmission connection with the pipeline cleaning assembly and the driving assembly A; the pipeline cleaning and detecting device can clean and detect pipelines with different inner diameters, and is stable in movement and high in detection accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline detection, and particularly to an ACFM alternating current magnetic field detection device and method. Background Art

[0002] ACFM alternating current magnetic field detection is a new type of non-destructive testing technology, mainly used to detect crack defects on the surface and near the surface of metal components. Its working principle is to induce a uniform alternating current in the workpiece through an excitation coil. When the induced current encounters defects such as cracks and corrosion, it will generate disturbances, resulting in distortion of the spatial magnetic field. By detecting the magnetic field distortion signals captured by the detection sensors, the detection and evaluation of defects can be realized.

[0003] Chinese Patent with publication number CN105911134B discloses an alternating current magnetic field detection device for in-pipeline detection, which includes: a cylinder having a hollow channel; a coil mechanism annularly arranged outside the cylinder, the coil mechanism is composed of a plurality of coil units, the plurality of coil units are uniformly arranged along the circumferential direction of the cylinder, and a plurality of sensors are arranged on the outer wall of each coil unit; a plurality of support mechanisms, the support mechanisms are connected between the coil units and the cylinder, and the coil units are radially movably connected to the outer wall of the cylinder through the support mechanisms. This invention can detect the inner wall of the pipeline, has a simple structure, is convenient to operate, has high detection accuracy, a long service life, and a wide application range.

[0004] However, this device still has deficiencies: the excitation coil or sensor in this device always keeps in close contact with the inner wall of the pipeline. When the device moves, the components in contact with the inner wall of the pipeline are extremely easy to be worn, and this device needs to be towed by a traction mechanism. At the same time, this device lacks a structure for cleaning the pipeline, and the dirt attached to the inner wall of the pipeline is extremely easy to generate adverse interference to the magnetic induction signals received by the sensors. Summary of the Invention

[0005] The object of the present invention is to propose an ACFM alternating current magnetic field detection device and method for the problems existing in the background art.

[0006] The technical solution of the present invention: On the one hand, the present invention proposes an ACFM alternating current magnetic field detection device, including a machine shell, and a plurality of guide grooves are annularly arranged around the axis of the machine shell. A swing arm A is rotatably arranged in each guide groove. One end of the swing arm A away from the machine shell is rotatably connected to a rotating shaft A. A roller A is coaxially arranged on the rotating shaft A, and the swing arm A is rotatably connected to a mounting frame. An excitation coil and a sensor are arranged on the mounting frame;

[0007] The swing arm B, the number of swing arms B is the same as that of swing arms A. Each swing arm B is respectively located in the corresponding guide groove and rotatably connected thereto. The swing arm B is parallel to the swing arm A. A roller B is provided on the swing arm B. One end of the mounting frame away from the swing arm A is rotatably connected to the swing arm B. The mounting frame is parallel to the radial direction of the machine shell;

[0008] The fixing frame is arranged inside the machine shell. A plurality of helical gears are rotatably arranged on the fixing frame in a circular array around the axis of the machine shell;

[0009] The driving component A is arranged on the fixing frame and drives the helical gear to rotate;

[0010] The transmission mechanism transmits and connects the helical gear and the rotating shaft A;

[0011] The sliding frame is slidably arranged inside the machine shell. A driving component B for driving the sliding frame to slide is arranged on the fixing frame;

[0012] The shock absorption component includes multiple groups. The two ends of the shock absorption component are respectively rotatably connected to the sliding frame and the corresponding swing arm B;

[0013] The pipeline cleaning component is rotatably arranged on the machine shell;

[0014] And the transmission component transmits and connects the pipeline cleaning component and the driving component A.

[0015] Preferably, the driving component A includes a helical gear disk and a motor A. The helical gear disk is rotatably connected to the fixing frame, and each helical gear meshes with the helical gear disk. The body of the motor A is connected to the fixing frame, and the output end of the motor A is connected to the helical gear disk.

[0016] Preferably, the pipeline cleaning component includes a rotating ring, a guiding frame, a slider, a U-shaped plate, a scraping plate and a spring B. The number of guiding frames is multiple groups; A central column coaxial with it is arranged on the machine shell. The rotating ring is rotatably arranged on the central column coaxially. Each guiding frame is connected to the side wall of the rotating ring, and multiple groups of guiding frames are distributed in a circular array around the axis of the central column; The slider is slidably arranged in the guiding frame. Each U-shaped plate is respectively slidably inserted into the corresponding guiding frame and connected to the slider. The scraping plate is connected to the end of the U-shaped plate away from the slider; A sliding rod is arranged in the guiding frame. The sliding rod penetrates through the slider and is slidably connected thereto. The spring B is sleeved on the sliding rod, and the two ends of the spring B respectively abut against the side of the slider close to the scraping plate and the inner wall of the guiding frame.

[0017] Preferably, the transmission component includes a rotating shaft D, a rotating shaft E and a gear D; The rotating shaft D is rotatably arranged on the machine shell and is coaxially connected to the helical gear disk. A gear A is coaxially arranged on the rotating shaft D; The rotating shaft E is rotatably arranged on the machine shell. A gear B and a gear C are coaxially arranged on the rotating shaft E. The gear B meshes with the gear A; The gear D is coaxially connected to the rotating ring, and the gear D meshes with the gear C.

[0018] Preferably, the transmission mechanism includes a transmission shaft, a bevel gear group and a universal joint, the bevel gear group includes multiple groups, each bevel gear group includes two bevel gears; the transmission shaft is rotatably set on the swing arm A, the two bevel gears in the same group are coaxially connected to the rotating shaft A and the transmission shaft, respectively, and the two bevel gears in the same group are meshed; the rotating shaft C is coaxially set on the helical gear, the rotating shaft C is rotatably connected to the fixed frame, the two ends of the universal joint are respectively connected to the rotating shaft C and the transmission shaft, and the swing arm A rotates around the cross axis center of the universal joint.

[0019] Preferably, the shock absorbing assembly includes an inner rod, an outer tube and a spring A. The ends of the inner rod and the outer tube that are away from each other are respectively rotatably connected to the slide and the swing arm B on the corresponding side. The inner rod is inserted into the outer tube and is slidably connected thereto. A support rod is arranged in the outer tube, and the support rod is inserted into the inner rod and is slidably connected thereto. The spring A is sleeved on the support rod, and the two ends of the spring A are respectively abutted against the inner wall of the outer tube and the end of the inner rod inserted into the outer tube.

[0020] Preferably, the distance between the excitation coil and the sensor and the housing is smaller than the distance between the roller A and the roller B and the housing.

[0021] On the other hand, the present invention also proposes an ACFM alternating current electromagnetic field detection method, which uses the above-mentioned ACFM alternating current electromagnetic field detection device and includes the following steps:

[0022] S1. Place the housing in the pipe, power it on, start the detection program, and then the driving component B drives the slide to approach the fixed frame, and the damping component opens the swing arm A and the swing arm B until the roller A and the roller B contact the inner wall of the pipe;

[0023] S2, start the excitation coil and the sensor to start detecting the pipeline;

[0024] S3, start the driving component A, the driving component A drives all the rollers A to rotate synchronously, so that the device moves in the pipeline, and during the movement, the pipeline cleaning component is driven to rotate at high speed through the transmission component, so that the dirt on the inner wall of the pipeline in the forward direction of the excitation coil and the sensor is cleaned.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] By setting the cooperation structure of the swing arm A, swing arm B, mounting frame, shock absorption component, carriage and drive component B, when the mounting frame can be synchronously expanded, when encountering an attachment block in the pipeline, the mounting frame on the corresponding side can also adaptively change and maintain a tensioned state; by setting the cooperation structure of the universal joint, helical gear and helical gear disk and bevel gear set, a group of motors can drive all the rollers A to rotate simultaneously, ensuring that the device can still move stably in the pipeline after one side of the rollers loses force; by setting an elastically telescopic scraper, the scraper is arranged on the swivel ring, and the swivel ring is linked with the helical gear disk through a gear set, so that the device automatically cleans the dirt in the advancing direction during the moving process, preventing the dirt from having an adverse impact on the detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0028] Figure 2 is a schematic connection diagram of the swing arm A and swing arm B with the fixed frame and the carriage;

[0029] Figure 3 is a schematic connection diagram of the swing arm A, swing arm B and the shock absorption component;

[0030] Figure 4 is a schematic connection diagram of the helical gear disk with the guide frame and the scraper.

[0031] Reference numerals: 1, housing; 101, guide groove; 2, swing arm A; 3, rotating shaft A; 4, roller A; 5, transmission shaft; 6, bevel gear set; 7, mounting frame; 8, excitation coil; 9, TMR sensor; 10, swing arm B; 11, rotating shaft B; 12, roller B; 13, fixed frame; 14, helical gear disk; 15, rotating shaft C; 16, helical gear; 17, universal joint; 18, motor A; 19, carriage; 20, shock absorption component; 21, lead screw; 22, motor B; 23, central column; 24, camera; 25, swivel ring; 26, transmission component; 261, rotating shaft D; 262, gear A; 263, rotating shaft E; 264, gear B; 265, gear C; 266, gear D; 27, guide frame; 28, slider; 29, U-shaped plate; 30, scraper; 31, slide bar; 32, spring B. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] Embodiment 1

[0033] As Figures 1-4As shown, an ACFM alternating current electromagnetic field detection device proposed by the present invention comprises a housing 1, a swing arm B10, a fixing frame 13, a driving assembly A, a transmission mechanism, a slide 19, a shock absorbing assembly 20, a pipe cleaning assembly and a transmission assembly 26. A handle is provided on the housing 1, and a control switch is provided on the handle. A plurality of guide grooves 101 are provided in a ring array around the axis of the housing 1, and a swing arm A2 is rotatably provided in each guide groove 101. The end of the swing arm A2 away from the housing 1 is rotatably connected to the rotating shaft A3, and a roller A4 is coaxially provided on the rotating shaft A3, and the swing arm A2 is rotatably connected to the mounting frame 7, and an excitation coil 8 and a sensor are provided on the mounting frame 7, and the sensor is a TMR sensor 9. The distance between the excitation coil 8 and the sensor and the housing 1 is smaller than the distance between the roller A4 and the housing 1. The number of swing arms B10 is the same as that of swing arms A2. Each swing arm B10 is respectively located in the guide groove 101 on the corresponding side and is rotatably connected thereto. The swing arm B10 is parallel to the swing arm A2. A rotating shaft B11 is arranged on the swing arm B10. A roller B12 is coaxially arranged on the rotating shaft B11. The end of the mounting frame 7 away from the swing arm A2 is rotatably connected to the swing arm B10. The mounting frame 7 is parallel to the radial direction of the housing 1. The fixed frame 13 is arranged in the housing 1. A plurality of helical gears 16 are rotatably arranged in a ring array around the axis of the housing 1 on the fixed frame 13. The driving assembly A is arranged on the fixed frame 13. The driving assembly A includes a helical gear plate 14 and a motor A18. The helical gear plate 14 is rotatably connected to the fixed frame 13, and each helical gear 16 is meshed with the helical gear plate 14. The body of the motor A18 is connected to the fixed frame 13, and the output end of the motor A18 is connected to the helical gear plate 14. The transmission mechanism is transmission-connected to the helical gear 16 and the rotating shaft A3. The slide 19 is slidably arranged in the housing 1, and a driving assembly B for driving the slide 19 to slide is arranged on the fixed frame 13, and the driving assembly B includes but is not limited to a screw rod 21 and a motor B22, and the two ends of the screw rod 21 are respectively rotatably connected with the fixed frame 13 and the housing 1, the screw rod 21 penetrates the slide 19 and is spirally connected thereto, the body of the motor B22 is connected to the fixed frame 13, and the output end of the motor B22 is connected to the screw rod 21. The shock absorbing assembly 20 includes multiple groups, and the shock absorbing assembly 20 includes an inner rod, an outer tube and a spring A, and the ends of the inner rod and the outer tube that are away from each other are respectively rotatably connected with the slide 19 and the swing arm B10 on the corresponding side, the inner rod is inserted into the outer tube and slidably connected thereto, a support rod is arranged in the outer tube, and the support rod is inserted into the inner rod and slidably connected thereto, and the spring A is sleeved on the support rod, and the two ends of the spring A are respectively abutted against the inner wall of the outer tube and the end of the inner rod inserted into the outer tube. The pipeline cleaning assembly is rotatably arranged on the housing 1, and the pipeline cleaning assembly includes a swivel 25, a guide frame 27, a slider 28, a U-shaped plate 29, a scraper 30 and a spring B32, and the number of the guide frames 27 is multiple groups. The housing 1 is provided with a central column 23 coaxial therewith, and the swivel 25 is coaxially rotatably arranged on the central column 23, each guide frame 27 is connected to the side wall of the swivel 25, and multiple groups of guide frames 27 are distributed in a ring array around the axis of the central column 23.The slider 28 is slidably arranged in the guide frame 27. Each U-shaped plate 29 is respectively slidably inserted into the guide frame 27 on the corresponding side and connected to the slider 28. The scraper 30 is connected to one end of the U-shaped plate 29 away from the slider 28. A slide bar 31 is arranged in the guide frame 27. The slide bar 31 penetrates through the slider 28 and is slidably connected to it. The spring B32 is sleeved on the slide bar 31. The two ends of the spring B32 respectively abut against one side of the slider 28 close to the scraper 30 and the inner wall of the guide frame 27. The scraper 30 is arranged obliquely in the vertical direction. And when the machine shell 1 advances in the pipeline, the scraper 30 pushes the scraped dirt along the advancing direction of the machine shell 1. The transmission assembly 26 includes a rotating shaft D261, a rotating shaft E263 and a gear D266. The rotating shaft D261 is rotatably arranged on the machine shell 1 and coaxially connected to the helical gear disc 14. A gear A262 is coaxially arranged on the rotating shaft D261. The rotating shaft E263 is rotatably arranged on the machine shell 1. A gear B264 and a gear C265 are coaxially arranged on the rotating shaft E263. The gear B264 meshes with the gear A262. The gear D266 is coaxially connected to the rotating ring 25. The gear D266 meshes with the gear C265.

[0034] In this embodiment, the housing 1 is placed in the pipeline, and the detection program is started after it is powered on. At this time, the motor B22 is started first and drives the screw 21 to rotate. The screw 21 drives the slide 19 to move toward the fixed frame 13, and then the swing arm B10 is opened through the shock absorbing assembly 20. The swing arm A2 is synchronously opened and maintained parallel to the swing arm B10 under the action of the swing arm B10 and the mounting frame 7 until the roller A4 and the roller B12 both contact the inner wall of the pipeline. At this time, due to the provision of the shock absorbing assembly 20, the swing arm A2 and the swing arm B10 on each side can be independently tensioned or retracted, so that when the device moves in the pipeline, if it encounters cracks or attachments that cannot be removed, the roller can directly pass over them, and the device will not lose balance due to the jumping of the rollers on one side. After the housing 1 is supported stably, the excitation coil 8 starts to work and emits a detection wave, and the TMR sensor works at the same time and collects the feedback wave to detect the inner wall of the pipeline. When the device moves, the motor A18 is started, and the motor A18 drives all the rollers A4 to rotate synchronously through the transmission mechanism, so that the device can move and measure in the pipeline. When the motor A18 drives the bevel gear plate 14 to rotate, the bevel gear plate 14 drives the rotating shaft D261 to rotate, the rotating shaft D261 drives the gear A262 to rotate, and the gear A262 drives the gear The wheel B264 and the rotating shaft E263 rotate, thereby driving the gear C265 to rotate. The gear C265 drives the gear D266 and the rotating ring 25 to rotate at high speed. Under the action of the high-speed rotating ring 25, the scraper 30 is subjected to the centrifugal force and adaptively slides to contact the inner wall of the pipe. The rotating scraper 30 rotates to clean and remove dirt from the inner wall of the pipe, and pushes the dirt along the forward direction of the device to avoid the dirt from having an adverse effect on the detection result. When the device stops moving forward, the scraper 30 automatically retracts and resets due to the tension of the spring B32.

[0035] Embodiment 2

[0036] like Figure 2 and Figure 3 As shown, an ACFM alternating current electromagnetic field detection device proposed by the present invention, compared with the first embodiment, this embodiment proposes a specific structure of a transmission mechanism, the transmission mechanism includes a transmission shaft 5, a bevel gear set 6 and a universal joint 17, the bevel gear set 6 includes multiple groups, and each bevel gear set 6 includes two bevel gears. The transmission shaft 5 is rotatably set on the swing arm A2, and the two bevel gears in the same group are coaxially connected to the rotating shaft A3 and the transmission shaft 5 respectively, and the two bevel gears in the same group are meshed. The rotating shaft C15 is coaxially set on the helical gear 16, and the rotating shaft C15 is rotatably connected to the fixed frame 13. The two ends of the universal joint 17 are respectively connected to the rotating shaft C15 and the transmission shaft 5, and the swing arm A2 rotates around the cross axis center of the universal joint 17.

[0037] In this embodiment, when the bevel gear plate 14 is driven to rotate by the motor A18, the bevel gear plate 14 drives the various bevel gears 16 to rotate synchronously in the same direction, and then drives the transmission shaft 5 to rotate synchronously in the same direction through the universal joint 17, and then drives the roller A4 to rotate through the bevel gear set 6, so that the device 1 moves inside the pipeline. Under this structure, no matter how the pitch angle of the swing arm A2 is adjusted, it will not affect the transmission efficiency of the transmission mechanism.

[0038] Embodiment 3

[0039] The present invention proposes an ACFM alternating current electromagnetic field detection method, which uses the ACFM alternating current electromagnetic field detection device described in the first or second embodiment, and specifically includes the following steps:

[0040] S1. Place the housing 1 in the pipe, power it on, start the detection program, and then the driving component B drives the slide 19 to approach the fixed frame 13, and uses the shock absorbing component to open the swing arm A2 and the swing arm B10 until the roller A4 and the roller B12 contact the inner wall of the pipe.

[0041] S2, start the excitation coil 8 and the sensor to begin detecting the pipeline.

[0042] S3, start the driving component A, which drives all rollers A4 to rotate synchronously, so that the device moves in the pipeline, and during the movement, the pipeline cleaning component is driven to rotate at high speed through the transmission component 26, so that the dirt on the inner wall of the pipeline in the forward direction of the excitation coil 8 and the sensor is cleaned.

[0043] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. An ACFM alternating current electromagnetic field detection device, characterized in that, including a casing (1) with a plurality of guide grooves (101) arranged in an annular array around its axis. A swing arm A (2) is rotatably arranged in each guide groove (101). One end of the swing arm A (2) away from the casing (1) is rotatably connected to a rotating shaft A (3). A roller A (4) is coaxially arranged on the rotating shaft A (3). The swing arm A (2) is rotatably connected to a mounting bracket (7), and an excitation coil (8) and a sensor are arranged on the mounting bracket (7); a swing arm B (10), the number of swing arms B (10) is the same as that of swing arms A (2). Each swing arm B (10) is respectively located in the corresponding guide groove (101) and rotatably connected thereto. The swing arm B (10) is parallel to the swing arm A (2). A roller B (12) is arranged on the swing arm B (10). One end of the mounting bracket (7) away from the swing arm A (2) is rotatably connected to the swing arm B (10), and the mounting bracket (7) is parallel to the radial direction of the casing (1); a fixing bracket (13) arranged in the casing (1), with a plurality of helical gears (16) rotatably arranged in an annular array around the axis of the casing (1) on the fixing bracket (13); a driving assembly A arranged on the fixing bracket (13) and driving the helical gears (16) to rotate; a transmission mechanism transmittingly connecting the helical gears (16) and the rotating shaft A (3); a carriage (19) slidably arranged in the casing (1), and a driving assembly B for driving the carriage (19) to slide is arranged on the fixing bracket (13); a shock absorption assembly (20), including multiple groups. The two ends of the shock absorption assembly (20) are respectively rotatably connected to the carriage (19) and the corresponding swing arm B (10); a pipeline cleaning assembly rotatably arranged on the casing (1); and a transmission assembly (26) transmittingly connecting the pipeline cleaning assembly and the driving assembly A.

2. The ACFM alternating current electromagnetic field detection device according to claim 1, characterized in that, The driving assembly A includes a helical gear disk (14) and a motor A (18). The helical gear disk (14) is rotatably connected to the fixing bracket (13), and each helical gear (16) meshes with the helical gear disk (14). The body of the motor A (18) is connected to the fixing bracket (13), and the output end of the motor A (18) is connected to the helical gear disk (14).

3. The ACFM alternating current electromagnetic field detection device according to claim 2, characterized in that, The pipeline cleaning assembly includes a swivel ring (25), a guide frame (27), a slider (28), a U-shaped plate (29), a scraper (30) and a spring B (32), and the number of guide frames (27) is multiple groups; a central column (23) coaxial with it is arranged on the housing (1), the swivel ring (25) is rotatably arranged on the central column (23) coaxially, each guide frame (27) is connected to the side wall of the swivel ring (25), and multiple groups of guide frames (27) are distributed in an annular array around the axis of the central column (23); the slider (28) is slidably arranged in the guide frame (27), each U-shaped plate (29) is slidably inserted into the corresponding side guide frame (27) and connected to the slider (28), and the scraper (30) is connected to the end of the U-shaped plate (29) away from the slider (28); a slide bar (31) is arranged in the guide frame (27), the slide bar (31) penetrates through the slider (28) and is slidably connected to it, the spring B (32) is sleeved on the slide bar (31), and the two ends of the spring B (32) are respectively abutted against the side of the slider (28) close to the scraper (30) and the inner wall of the guide frame (27).

4. An ACFM alternating current magnetic field detection device according to claim 3, characterized in that, The transmission assembly (26) includes a rotating shaft D (261), a rotating shaft E (263) and a gear D (266); the rotating shaft D (261) is rotatably arranged on the housing (1) and is coaxially connected to the helical gear disk (14), and a gear A (262) is coaxially arranged on the rotating shaft D (261); the rotating shaft E (263) is rotatably arranged on the housing (1), a gear B (264) and a gear C (265) are coaxially arranged on the rotating shaft E (263), and the gear B (264) meshes with the gear A (262); the gear D (266) is coaxially connected to the swivel ring (25), and the gear D (266) meshes with the gear C (265).

5. An ACFM alternating current electromagnetic field detection device according to claim 1, characterized in that, The transmission mechanism includes a transmission shaft (5), a bevel gear set (6) and a universal joint (17), the bevel gear set (6) includes multiple groups, and each group of bevel gear sets (6) includes two bevel gears; the transmission shaft (5) is rotatably arranged on the swing arm A (2), and the two bevel gears in the same group are respectively coaxially connected to the rotating shaft A (3) and the transmission shaft (5), and the two bevel gears in the same group mesh; a rotating shaft C (15) is coaxially arranged on the helical gear (16), the rotating shaft C (15) is rotatably connected to the fixed frame (13), and the two ends of the universal joint (17) are respectively connected to the rotating shaft C (15) and the transmission shaft (5), and the swing arm A (2) rotates around the center of the cross shaft of the universal joint (17).

6. An ACFM alternating current magnetic field detection device according to claim 1, characterized in that, The shock absorption assembly (20) includes an inner rod, an outer tube and a spring A. The ends of the inner rod and the outer tube away from each other are respectively rotatably connected to the carriage (19) and the corresponding side swing arm B (10). The inner rod is inserted into the outer tube and is slidably connected to it. A support rod is arranged in the outer tube, the support rod is inserted into the inner rod and is slidably connected to it. The spring A is sleeved on the support rod, and the two ends of the spring A are respectively abutted against the inner wall of the outer tube and the end of the inner rod inserted into the outer tube.

7. An ACFM alternating current magnetic field detection device according to claim 1, characterized in that, The distances between the excitation coil (8) and the sensor and the housing (1) are less than the distances between the roller A (4) and the roller B (12) and the housing (1).

8. An ACFM alternating current magnetic field detection method, which uses the ACFM alternating current magnetic field detection device described in any one of claims 1-7, is characterized in that, It includes the following steps: S1, placing the housing (1) in a pipe, powering it on, starting the detection program, the driving component B drives the slide (19) to approach the fixed frame (13), and the swing arm A (2) and the swing arm B (10) are spread open through the shock absorbing component until the roller A (4) and the roller B (12) are in contact with the inner wall of the pipe; S2, starting the excitation coil (8) and the sensor to begin detecting the pipeline; S3, start the driving component A, which drives all the rollers A (4) to rotate synchronously, so that the device moves in the pipeline, and during the movement, the pipeline cleaning component is driven to rotate at high speed through the transmission component (26), so that the dirt on the inner wall of the pipeline in the forward direction of the excitation coil (8) and the sensor is cleaned.

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