Automatic magnetic flux leakage flaw detection device and method for internal connection quality of reinforcing steel bar sleeve

Abstract

The invention discloses an automatic magnetic flux leakage flaw detection device and method for the internal connection quality of a steel bar sleeve, the automatic magnetic flux leakage flaw detection device for the internal connection quality of the steel bar sleeve comprises a shell, a magnetizing device and an automatic flaw detection assembly, the magnetizing device comprises a magnetizer shell and a magnetizer, and the magnetizer is installed on the magnetizer shell; the automatic flaw detection assembly comprises a guide rail, a sliding block, a driving motor, a transmission mechanism, a detection shoe support and a magnetic induction sensor, the sliding block is slidably installed on the guide rail, the driving motor is connected with the sliding block through the transmission mechanism, the detection shoe support is fixed to the sliding block, and the magnetic induction sensor is installed on the detection shoe support. The magnetic flux leakage detector is used for detecting magnetic flux leakage information on the surface of the reinforcing steel bar sleeve in the moving process of the sliding block. Based on the principle that after the reinforcement sleeve is connected with the two reinforcements and magnetized by the magnetizing device, magnetic field distortion can be generated in the gap between the two reinforcements of the reinforcement sleeve assembly, the defect signal in the reinforcement sleeve can be quickly captured under the condition that a component is not damaged, and the operation is simple and convenient.

Description

Technical Field

[0001] This invention belongs to the field of building safety monitoring, and more specifically, relates to an automatic magnetic flux leakage detection device and method for the internal connection quality of steel bar sleeves. Background Technology

[0002] In modern construction engineering, rebar couplers, as a crucial connecting component, are widely used in rebar cages, frame structures, and other components. Their connection quality directly affects the overall mechanical performance, seismic stability, and long-term service durability of the building structure. Rebar couplers are typically used to connect two rebars, achieving an effective connection through a threaded connection. However, in actual construction, the connection quality of rebar couplers is affected by various factors, which may lead to connection defects, thus posing a potential threat to the safety of the building structure.

[0003] During the rebar sleeve connection process, the two rebars need to be precisely aligned and inserted into the sleeve. However, due to the inaccuracy of construction operations, rebar processing errors, and the complexity of the on-site construction environment, there may be coaxiality deviations between the rebars and the sleeve. This deviation can lead to uneven contact between the rebars and the sleeve, potentially resulting in localized gaps, thereby weakening the rebar sleeve connection strength.

[0004] The connection quality of rebar sleeves also depends on the effective engagement length between the rebar and the sleeve. If the engagement length is insufficient, the connection strength between the rebar and the sleeve will not meet the design requirements. In actual construction, insufficient rebar processing precision, sleeve manufacturing errors, or improper construction operations may lead to insufficient insertion depth of the rebar into the sleeve, thus affecting the reliability of the connection. For example, in some complex rebar cage structures, bending or twisting of the rebar may prevent it from fully inserting into the sleeve, thereby reducing the effectiveness of the connection.

[0005] Furthermore, when connecting reinforcing bars with threaded sleeves, operational errors may result in the ends of the two reinforcing bars failing to fit tightly together inside the sleeve, creating gaps that directly weaken the overall strength of the reinforcing cage and pose serious structural safety hazards.

[0006] Although the importance of the quality of rebar sleeve connections is self-evident, current testing methods still have many limitations and are difficult to meet the needs of actual engineering projects.

[0007] Magnetic flux leakage (MFL) testing is a commonly used non-destructive testing (NDT) technique that identifies surface or internal defects in materials by detecting changes in magnetic fields. However, traditional MFL testing has several limitations when applied to inspecting rebar sleeves. Traditional testing typically relies on manual, handheld probe movement. Because manual operation makes it difficult to maintain a perfectly uniform probe movement speed and is prone to vibration, this leads to unstable detection signals and even missed or false positives. Furthermore, the diameters of rebars and sleeves at construction sites vary, and traditional testing probes or magnetization structures are often designed in a fixed manner, unable to flexibly adapt to components of different diameters. When inspecting sleeves of different diameters, the distance between the magnetic sensor and the workpiece surface (lift-off value) changes. If the lift-off value cannot be controlled within an effective range, the accuracy of magnetic field signal capture will be severely affected.

[0008] Besides magnetic flux leakage testing, other inspection methods are used to inspect the quality of rebar sleeve connections, such as ultrasonic testing and radiographic testing. However, these methods also have their limitations. While ultrasonic testing can detect internal defects, it requires highly skilled personnel and involves complex and inconvenient equipment. Radiographic testing, while providing relatively intuitive images of the internal structure, poses radiation hazards and is costly, making it unsuitable for large-scale application. Furthermore, most of these methods require complex preparation of the components being inspected, such as surface cleaning and application of coupling agent, increasing the difficulty and time cost of inspection. Summary of the Invention

[0009] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides an automatic magnetic flux leakage detection device and method for the internal connection quality of rebar sleeves. It utilizes the principle that after the rebar sleeve connects two rebars and is magnetized by a magnetizing device, the defects inside the rebar sleeve will generate magnetic field distortion. It can quickly capture surface and internal defect signals without damaging the component. It has the advantages of portability, high degree of automation and simple operation.

[0010] To achieve the above objectives, according to one aspect of the present invention, an automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves is provided, comprising a housing and a magnetizing device and an automatic flaw detection assembly mounted on the housing, wherein: The magnetization device includes a magnetizer housing and a magnetizer. The magnetizer housing is mounted on the outer shell, and the magnetizer is mounted on the magnetizer housing. It is used to adsorb and magnetize the rebar sleeve assembly to be tested. The rebar sleeve assembly includes a rebar sleeve and two rebars connected to the rebar sleeve. The automatic flaw detection assembly includes a guide rail, a slider, a drive motor, a transmission mechanism, a probe shoe bracket, and a magnetic induction sensor. The length direction of the guide rail is consistent with the axial direction of the rebar sleeve. The slider is slidably mounted on the guide rail. The drive motor is connected to the slider through the transmission mechanism to drive the slider to move on the guide rail. The probe shoe bracket is fixed on the slider. The magnetic induction sensor is mounted on the probe shoe bracket to scan the surface of the rebar sleeve to obtain leakage magnetic signals as it moves with the slider.

[0011] Preferably, the outer casing includes a main casing and a handle, the handle is fixed to the main casing, one end of the main casing extends to a grip, the handle is located between the rebar sleeve and the grip, and the distance from the handle to the rebar sleeve is less than the distance from the handle to the grip, so that the outer casing can be rotated with the handle as a fulcrum to separate the magnetizer from the rebar sleeve. The automatic flaw detection component and the magnetization device are both installed inside the main housing. The main housing is provided with a motor signal input port and a leakage magnetic signal output port. The motor signal input port and the leakage magnetic signal output port are respectively connected to the drive motor and the magnetic induction sensor.

[0012] Preferably, the system further includes a detector, which comprises a motor drive module, a data acquisition module, a signal processing module, a main control board, and a data display module. The motor drive module is electrically connected to the drive motor, and the data acquisition module is electrically connected to the magnetic induction sensor. The data acquisition module is used to acquire leakage magnetic signals and transmit them to the signal processing module. The signal processing module transmits the processed signals to the main control board. The main control board is used to perform logical analysis on the processed leakage magnetic signals and display the analysis results on the data display module.

[0013] Preferably, it further includes two photoelectric limit switches arranged along the length of the guide rail and both of them are fixed on the guide rail.

[0014] Preferably, the probe shoe bracket includes a sensor bracket and a detection plate, the magnetic induction sensor is mounted on the sensor bracket, and the detection plate is used to cooperate with the photoelectric limit switch.

[0015] Preferably, the magnetizer includes a semi-circular annular magnet and two armatures fixed on the semi-circular annular magnet. The two armatures are symmetrically arranged at both ends of the semi-circular annular magnet and are arranged along the axial direction of the semi-circular annular magnet. Each armature is provided with a V-shaped groove to fit against the rebar sleeve and to keep the rebar sleeve at a distance from the inner wall of the semi-circular annular magnet.

[0016] Preferably, a spacer is also installed on the magnetizer housing, the spacer being located between the steel sleeve and the magnetic induction sensor to protect the magnetic induction sensor, and there is a gap between the spacer and the magnetizer to accommodate the probe shoe bracket and the magnetic induction sensor on the probe shoe bracket, the magnetic induction sensor being located between the spacer and the magnetizer.

[0017] Preferably, the transmission mechanism is a belt drive mechanism, and includes two pulleys and a belt connecting the two pulleys. One pulley is connected to the output shaft of the drive motor, and the other pulley is mounted on a support. The support is mounted on the housing, and the slider is mounted on the belt.

[0018] Preferably, the magnetic induction sensor employs an induction coil or a Hall element, wherein: When the magnetic induction sensor uses an induction coil, the induction coil is a single-layer coil winding or a multi-layer coil winding composed of multiple turns of coil tightly bonded together, and when there are no less than two induction coils, the number of layers of coil windings of each induction coil is the same.

[0019] According to another aspect of the present invention, a flaw detection method for the automatic magnetic flux leakage flaw detection device for the internal connection quality of the rebar sleeve is also provided, comprising the following steps: 1) The magnetizer attracts the rebar sleeve assembly and magnetizes the rebar sleeve and the portion of each rebar located inside the rebar sleeve; 2) The drive motor drives the slider to move through the transmission mechanism. The slider drives the probe shoe bracket and the magnetic induction sensor to move along the length of the guide rail. During the movement of the magnetic induction sensor, the magnetic induction sensor scans the surface of the rebar sleeve to obtain the leakage magnetic signal. 3) The detector receives the leakage magnetic signal transmitted by the magnetic induction sensor to determine whether the two steel bars connected by the steel bar sleeve are abutting each other or whether there is a gap between the steel bar and the steel bar sleeve. 4) Separate the magnetizer from the rebar sleeve.

[0020] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1) The automatic magnetic flux leakage flaw detection device for the internal connection quality of the rebar sleeve of the present invention magnetizes the rebar sleeve and generates a magnetic flux leakage field on its surface. By using a magnetic induction sensor to capture the changes in the magnetic field, it can quickly identify whether there is a gap between the two rebars connected by the rebar sleeve on the rebar cage and the length of the gap, thereby judging the connection quality of the rebar sleeve. This non-destructive testing method not only avoids damage to the components, but also achieves high-precision defect identification, significantly improving the reliability and accuracy of the detection.

[0021] 2) The automatic magnetic flux leakage flaw detection device for the internal connection quality of the rebar sleeve of the present invention, through the coordinated action of the drive motor and the transmission mechanism, allows the slider to move automatically along the guide rail with the probe shoe bracket, and the magnetic induction sensor to realize continuous scanning of the surface of the rebar sleeve. Compared with the traditional manual probe movement method, this automated design greatly improves the detection efficiency and reduces the detection time. Attached Figure Description

[0022] Figure 1 This is a three-dimensional schematic diagram of the present invention; Figure 2 This is a bottom view of the present invention; Figure 3 This is a schematic diagram of the outer casing of the present invention after a portion of the structure has been removed. Figure 4 This is a schematic diagram of the present invention after the outer casing has been removed; Figure 5 This is a schematic diagram of the probe shoe support moving to one end of the magnetization device in this invention; Figure 6 This is a schematic diagram of the magnetizer in this invention; Figure 7 This is a schematic diagram of the probe shoe bracket in this invention; Figure 8 This is a schematic diagram of the automatic flaw detection component in this invention; Figure 9 This is a schematic diagram of the detector in this invention.

[0023] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1. Outer shell; 2. Magnetizing device; 3. Magnet; 4. Magnetizer housing; 5. Magnetizer; 6. Limiting support; 7. Spacer; 8. Motor signal input port; 9. Photoelectric limit switch; 10. Handle; 11. Slider; 12. First housing; 13. Second housing; 14. Module fixing bracket; 15. Motor mounting base; 16. Probe shoe bracket; 17. Detection plate; 18. Automatic flaw detection component; 19. Leakage magnetic signal input port; 20. Power switch; 21. Motor signal output port; 22. Charging port; 24. Detection switch; 25. Detector; 26. Power display module; 30. Data display module; 41. Guide rail; 51. Belt; 55. Armature; 61. Drive motor; 66. Sensor bracket; 81. Leakage magnetic signal output port. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Reference Figures 1-9 The automatic magnetic flux leakage flaw detection device for the internal connection quality of the rebar sleeve includes a housing 1, a magnetizing device 2 and an automatic flaw detection assembly 18 mounted on the housing 1, wherein: The magnetization device 2 includes a magnetizer housing 4 and a magnetizer 5. The magnetizer housing 4 is mounted on the outer casing 1, and the magnetizer 5 is mounted on the magnetizer housing 4. It is used to attract and magnetize the rebar sleeve assembly to be tested. The rebar sleeve assembly includes a rebar sleeve and two rebars connected to the sleeve. The magnetizer housing 4 is used to mount the magnetizer 5, and after assembly, a sealing process is performed to further stabilize the overall magnetic flux leakage detection device.

[0026] The automatic flaw detection assembly 18 includes a guide rail 41, a slider 11, a drive motor 61, a transmission mechanism, a probe shoe bracket 16, and a magnetic induction sensor. The length direction of the guide rail 41 is consistent with the axial direction of the rebar sleeve. The slider 11 is slidably mounted on the guide rail 41. The drive motor 61 is preferably mounted on the housing 1 via a motor mounting base 15. The drive motor 61 is preferably a stepper motor. The drive motor 61 is connected to the slider 11 through the transmission mechanism to drive the slider 11 to move on the guide rail 41. The probe shoe bracket 16 is fixed to the slider 11. The magnetic induction sensor is mounted on the probe shoe bracket 16 and is used to scan the surface of the rebar sleeve to obtain leakage magnetic signals during the movement of the slider 11. (The magnetic induction sensor does not directly contact the metal wall of the rebar sleeve, but relies on the magnetic field leaking to the outside of the rebar sleeve for sensing. Regardless of whether there is a physical leakage magnetic field, the magnetic induction sensor is always working and outputting an electrical signal. If the rebar sleeve assembly is defect-free, the output is a zero signal; if the rebar sleeve assembly is defective, the output is an abnormal leakage magnetic signal.)

[0027] This invention mainly utilizes a rebar sleeve to connect two rebars. If the connection between the rebar and the rebar sleeve is poor, such as there is a gap between them, or the ends of the two rebars inside the rebar sleeve do not abut together and there is a gap, these gaps can be regarded as defects. After the rebar sleeve and the part of each rebar inside the rebar sleeve are magnetized by a magnetizer, a leakage magnetic field will be generated at the gap and detected by a magnetic induction sensor.

[0028] Furthermore, the outer casing 1 includes a main casing and a handle 10. The handle 10 is fixed to the main casing, and a grip extends from one end of the main casing. The handle 10 is located between the rebar sleeve and the grip, and the distance from the handle 10 to the rebar sleeve is less than the distance from the handle 10 to the grip, so that the outer casing 1 can be rotated with the handle 10 as a fulcrum to separate the magnetizer 5 from the rebar sleeve. This design cleverly utilizes the lever principle; the distance from the handle 10 to the rebar sleeve is less than the distance from the handle 10 to the grip, allowing the handle 10 to act as a fulcrum. Through a simple rotation operation, the magnetizer 5 can be quickly separated from the rebar sleeve, making it easy to remove the device from the rebar cage. The middle part of the main casing is recessed inward, with a certain protrusion at the end forming a grip, and the handle 10 is installed at the front end. The main casing includes a first casing 12 and a second casing 13. The first casing 12 is mainly used to accommodate the magnetization device 2, and the second casing 13 is mainly used to accommodate the automatic flaw detection assembly 18.

[0029] The automatic flaw detection assembly 18 and the magnetization device 2 are both installed inside the main housing. The main housing is provided with a motor signal input port 8 and a magnetic flux leakage signal output port 81, which are respectively connected to the drive motor 61 and the magnetic induction sensor. The motor signal input port 8 and the magnetic flux leakage signal output port 81 enable the automatic flaw detection assembly 18 and the magnetization device 2 to be seamlessly connected to the external detector 25. This modular design not only facilitates equipment maintenance and upgrades but also improves the overall performance and reliability of the equipment. The side of the main housing is provided with a magnetizer positioning hole, which can fix the magnetizer 5 above, so that the magnetizer 5 can maintain a stable position without deviation when inspecting strongly magnetic steel bar sleeve components.

[0030] Furthermore, it also includes a detector 25, which includes a motor drive module, a data acquisition module, a signal processing module, a main control board, and a data display module 30. The motor drive module is electrically connected to the drive motor 61, and the data acquisition module is electrically connected to the magnetic induction sensor. It is used to acquire leakage magnetic signals and transmit them to the signal processing module. The signal processing module transmits the processed signals to the main control board. The main control board is used to perform logical analysis on the processed leakage magnetic signals and display the analysis results on the data display module 30.

[0031] The detector 25 is connected to the drive motor 61 of the automatic flaw detection component 18 via a motor drive module, enabling precise control of the moving speed and position of the magnetic induction sensor. The data acquisition module can acquire the leakage magnetic signal from the magnetic induction sensor in real time, and perform filtering, amplification, and other processing through the signal processing module, further improving the quality of the detection signal. The main control board performs logical analysis on the processed signal and displays the results intuitively on the data display module 30, realizing intelligent and automated detection. The detector 25, through its integrated data acquisition and processing module, can accurately analyze the leakage magnetic signal. The main control board controls the drive motor 61 based on the photoelectric switch status and control button input status. The detector 25 also features a power display module and a charging port 22.

[0032] During testing, connect the leakage magnetic signal input port 19 of the detector to the leakage magnetic signal output port 81 on the housing, and connect the motor signal output port 21 of the detector to the motor signal input port 8 on the housing. The testing steps are as follows: Press the power switch 20. At this time, the automatic magnetic flux leakage detector will reset and the data display module will show the values, namely the offset and the gap, with a value of 0.00.

[0033] Press the detection switch 24 to perform the detection. If there are no defects inside the steel sleeve, the digital tube will still display a value of 0.00; if there are defects, the digital tube will display the corresponding defect value.

[0034] If the battery level is too low, it will affect the test results. In this case, the detector 25 should be charged through the charging port 22.

[0035] Furthermore, it also includes two photoelectric limit switches 9 arranged along the length of the guide rail 41 and both of them are fixed on the guide rail 41. The photoelectric limit switches 9 are preferably connected to the guide rail 41 through the module fixing bracket 14, and the photoelectric limit switches 9 are fixed on the module fixing bracket 14. The magnetic induction sensor does not contact the photoelectric limit switches 9.

[0036] The introduction of the photoelectric limit switch 9 provides precise position control for the movement of the automatic flaw detection assembly 18. During the detection process, the slider 11 drives the probe shoe bracket 16 and the magnetic induction sensor to move along the guide rail 41. When the detection piece 17 on the probe shoe bracket 16 triggers the photoelectric limit switch 9, the drive motor 61 stops or reverses. This design ensures that the probe can accurately cover the entire surface of the rebar sleeve during the detection process, avoiding detection omissions or repeated detections due to positional deviations. By precisely controlling the probe's movement range, the photoelectric limit switch 9 significantly improves the accuracy and reliability of the detection.

[0037] Furthermore, the probe shoe bracket 16 includes a sensor bracket 66 and a detection piece 17. The magnetic induction sensor is mounted on the sensor bracket 66, and the detection piece 17 is used to cooperate with the photoelectric limit switch 9.

[0038] The sensor bracket 66 has a through slot for fixing the sensor signal line. The sensor bracket 66 has an arc-shaped portion with an open slot. When the number of sensors is no more than two, the open slot is located at the end of the arc-shaped portion. When the number of magnetic induction sensors is greater than two, the open slots are evenly distributed on the arc-shaped portion. The detection piece 17 has a protruding structure, which is used to trigger the photoelectric limit switch 9. When the slider 11 moves the probe shoe bracket 16 to the specified position, the light signal of the photoelectric limit switch 9 is blocked by the detection piece 17, triggering a change in the switch state and outputting a corresponding limit signal to the control system. This signal is used to determine whether the probe shoe bracket 16 has moved to the specified position, thus realizing the position detection and stroke control of the moving parts.

[0039] When the probe shoe bracket 16 includes one magnetic induction sensor, the magnetic induction sensor is located at the intersection of the axis of symmetry of the arc-shaped portion and the arc-shaped portion. When there are at least two magnetic induction sensors, each magnetic induction sensor should be evenly distributed on the arc-shaped portion, and the detection direction should be axial or radial; preferably, the detection direction of the magnetic induction sensor is axial.

[0040] The arc-shaped design of the probe shoe bracket 16 can accommodate rebar sleeves of different diameters. This arrangement of magnetic induction sensors not only improves the uniformity and comprehensiveness of the detection but also reduces signal deviation caused by inconsistent sensor positions, significantly enhancing detection accuracy and signal quality. When multiple magnetic induction sensors are installed on the probe shoe bracket 16, these sensors are circumferentially evenly distributed on the arc-shaped portion. This multi-sensor layout can simultaneously acquire leakage magnetic signals from multiple locations, significantly improving detection efficiency. Compared to using only a single magnetic induction sensor, the multi-sensor layout can acquire more data in a single scan, reducing the need for repeated detections and shortening detection time. Furthermore, the multi-sensor layout can further improve the accuracy of defect identification through signal comparison and analysis.

[0041] Furthermore, the magnetizer 5 includes a semi-circular annular magnet 3 and two armatures 55 fixed on the semi-circular annular magnet 3. The two armatures 55 are symmetrically arranged at both ends of the semi-circular annular magnet 3 and are arranged along the axial direction of the semi-circular annular magnet 3. Each armature 55 is provided with a V-shaped groove for contacting the rebar sleeve and keeping the rebar sleeve at a distance from the inner wall of the semi-circular annular magnet 3.

[0042] This structure can accommodate rebar sleeves of different diameters (e.g., 16mm-28mm), ensuring stable contact between the magnetizer 5 and the rebar sleeve during testing. The V-groove design allows the rebar sleeve to be firmly positioned during testing, avoiding testing errors caused by sleeve wobbling or positional displacement. This adaptable design not only improves the versatility of the device.

[0043] The combination of the semi-circular magnet 3 and the armature 55 with a V-groove optimizes the magnetization effect. The semi-circular magnet 3 generates a uniform and stable magnetic field, allowing the leakage magnetic field of the rebar sleeve to be fully excited during the magnetization process. This magnetizer 5 can more thoroughly magnetize the rebar sleeve assembly, meeting the requirements for detecting deeply buried defects.

[0044] To accommodate the inspection of steel bar sleeve components with different diameters, the steel bar (quasi-cylindrical) is limited by the double-sided limiting principle of the V-groove. The maximum displacement of the steel bar sleeve surface inspection for diameter specifications of 16-28mm is 3mm.

[0045] A limiting support 6 is installed on the magnetizer housing 4. The limiting support 6 restricts the detection area of ​​the rebar sleeve through its double-sided position, ensuring that the rebar sleeve assembly is placed within the detection range of the magnetic induction sensor. At the same time, it presses the magnet 3 and armature 55 inside the magnetizer housing 4 to prevent the sleeve assembly from shifting position due to magnetic force during detection. A spacer 7 is fixed to the limiting support 6 and has a curved arc surface in the middle. It isolates the detected rebar sleeve assembly from the probe shoe bracket 16, protecting the probe shoe bracket 16 from being impacted by the rebar sleeve assembly during detection.

[0046] Furthermore, a spacer 7 is installed on the magnetizer housing 4. The spacer 7 is located between the rebar sleeve and the magnetic induction sensor to protect the magnetic induction sensor. A gap exists between the spacer 7 and the magnetizer 5 to accommodate the probe shoe bracket 16 and the magnetic induction sensor on the probe shoe bracket 16. The magnetic induction sensor is located between the spacer 7 and the magnetizer 5. The main function of the spacer 7 is to protect the magnetic induction sensor and prevent it from being mechanically damaged during detection. During magnetic flux leakage detection, the distance between the magnetic induction sensor and the object being detected directly affects the sensitivity and accuracy of the signal. The spacer 7, while protecting the magnetic induction sensor, also ensures that the distance between the magnetic induction sensor and the rebar sleeve remains within the optimal range by providing a pre-existing gap.

[0047] The spacer 7 is preferably made of stainless steel. The spacer 7 is preferably mounted on the magnetizer housing 4 by a limiting support 6, so that the magnetic induction sensor does not come into contact with the spacer 7 when it moves.

[0048] Furthermore, the transmission mechanism is a belt drive mechanism, including two pulleys and a belt 51 connecting the two pulleys. The belt 51 is preferably a synchronous belt. One pulley is connected to the output shaft of the drive motor 61, and the other pulley is mounted on a support. The support is mounted on the outer casing 1, and the slider 11 is mounted on the belt 51. When the drive motor 61 is running, the output shaft drives the active synchronous pulley to rotate, which is then converted into linear motion via the synchronous belt, driving the slider 11 to reciprocate linearly along the guide rail 41, thus achieving transmission. The belt drive can automatically adjust the tension through the elastic deformation of the belt 51, thereby reducing slippage during transmission and ensuring that the power of the drive motor 61 can be efficiently and stably transmitted to the slider 11. The design of the belt drive mechanism allows the device to adapt to different detection speeds and stroke requirements. By adjusting the length of the belt 51 and the diameter of the pulleys, the transmission ratio can be flexibly changed, thereby achieving precise control over the moving speed and position of the slider 11.

[0049] Furthermore, the magnetic induction sensor employs an induction coil or a Hall element, wherein: When the magnetic induction sensor uses an induction coil, the induction coil is composed of a coil winding made of multiple turns of wire tightly wound together, and when there are at least two induction coils, the number of layers of the coil winding of each induction coil is the same.

[0050] Induction coils are constructed by tightly bonding multiple turns of coil to form one or more coil windings. This structure significantly improves signal sensitivity and strength. When there is a gap inside a steel sleeve connecting two steel bars, the change in the leakage magnetic field is efficiently captured by the induction coil and converted into an electrical signal. Compared to single-turn coils, multi-turn induction coils can detect minute changes in the magnetic field more sensitively, thereby improving detection accuracy and enabling the device to identify smaller defects. The design of multi-turn induction coils not only improves signal sensitivity but also enhances signal stability and consistency. Because multi-turn coils can more evenly distribute the magnetic field sensing area, signal fluctuations caused by local magnetic field changes are reduced. This stable signal output is crucial for subsequent data acquisition and processing, ensuring the reliability and repeatability of detection results. Especially when detecting minute defects, stable signal output can avoid misjudgments and missed detections.

[0051] According to another aspect of the present invention, a method for detecting magnetic flux leakage in the rebar sleeve connection quality of the device is also provided, comprising the following steps: 1) Magnetizer 5 attracts the rebar sleeve and magnetizes the rebar sleeve and the portion of each rebar located inside the rebar sleeve; 2) The drive motor 61 drives the slider 11 to move through the transmission mechanism. The slider 11 drives the probe shoe bracket 16 and the magnetic induction sensor to move along the length direction of the guide rail 41. During the movement of the magnetic induction sensor, the magnetic induction sensor scans the surface of the rebar sleeve to obtain the leakage magnetic signal. 3) The detector 25 receives the leakage magnetic signal transmitted by the magnetic induction sensor to determine whether the two steel bars connected by the steel bar sleeve are abutting each other or whether there is a gap between the steel bar and the steel bar sleeve. 4) Separate the magnetizer 5 from the steel bar sleeve.

[0052] This flaw detection method ensures a comprehensive scan of the surface and internal defects of the rebar sleeve by precisely controlling the probe's movement path and speed. A magnetic induction sensor collects magnetic field signals in real time during the movement; these signals are processed and analyzed by the detector 25 to accurately identify minute defects at the rebar sleeve connection, such as cracks and incomplete engagement. The photoelectric limit switch 9 controls the probe's movement range, further ensuring the accuracy and consistency of the detection process and significantly improving the reliability of the detection results.

[0053] This flaw detection method significantly shortens the inspection time through automated control and intelligent processing. The drive motor 61 moves the probe rapidly along the guide rail 41, enabling a quick scan of the entire rebar sleeve. Simultaneously, the detector 25 processes the acquired signals in real time and displays the results quickly, reducing time wasted due to data processing delays.

[0054] To address the challenge of non-destructive testing of rebar sleeve assemblies on construction sites, magnetic flux leakage detection technology is applied to detect the internal connection status (connection quality) of the rebar sleeve, deeply exciting the rebar sleeve assembly. If the two rebars connected by the rebar sleeve are not abutting together, there will be a gap between them. This gap is equivalent to a defect in the rebar sleeve assembly, generating a magnetic flux leakage field, which can be detected by a magnetic induction sensor.

[0055] To address the issue that the detection probe cannot be matched with rebar sleeve components of various diameters, the magnetizer 5 of this invention can adapt to rebar sleeves with diameters ranging from 16mm to 28mm. When testing rebar sleeves of different specifications, this structure can ensure that the magnetic induction sensor is no more than 3mm away from the surface of the rebar sleeve, thereby achieving high-precision magnetic field signal capture.

[0056] To address the issue that traditional magnetic flux leakage testing requires manual movement of the probe to obtain information about different positions of the rebar sleeve assembly, this invention uses a drive motor 61 to drive the magnetic induction sensor to move and achieve automated scanning, further reducing the detection space required by the instrument and making it more suitable for rebar sleeve detection in narrow spaces.

[0057] In response to the need for portable assembly and disassembly of the testing instrument 25 at actual construction sites, and the common problem of large magnetic attraction of magnetic flux leakage test probes, this invention adopts a shell 1 that conforms to the principle of lever mechanics. Through the structural design of the handle 10 and the grip platform, rapid on-site testing can be achieved.

[0058] To address the issue of redundant back-end testing equipment, the detector 25 of this invention adopts a modular design, integrating a stepper motor drive module, a signal processing module, a signal acquisition module, and a main control module, thereby achieving a portable structure.

[0059] The automatic flaw detection component 18 provided by this invention, which uses a stepper motor to drive the probe shoe for detection, reduces the required detection space compared to most existing systems that rely on manual movement of the magnetic induction sensor. Furthermore, the pulse-triggered control of the drive motor 61 enhances the intelligence of the detection process. The magnetic induction sensor, in conjunction with the photoelectric limit switch 9, possesses both magnetic field capture and limit triggering functions. Compared to traditional automated detection devices that rely on external encoders for displacement calculation, the automatic flaw detection component 18 of this invention integrates stepper motor pulse information and photoelectric switch limit information to ensure strong repeatability of each detection result.

[0060] The magnetic flux leakage detection device provided by this invention uses a semi-ring magnetizer 5. Compared with the traditional magnetic yoke magnetization structure, this invention enables the rebar sleeve assembly to be magnetized more thoroughly, obtaining more magnetic flux leakage information. The magnetizer 5 effectively excites the magnetic flux leakage of the rebar sleeve assembly, rather than only exciting damage on the outer surface. At the same time, the armature 55 structure controls the axial position fluctuation of rebar columns of different diameters within a limited range through bilateral limiting with the rebar column. Therefore, rebars of different diameters can be detected, making the instrument more versatile.

[0061] Compared with the traditional single-bend handle structure, the outer shell 1 provided by the present invention adopts the lever principle, using the handle 10 and the end of the outer shell 1 as the fixed point and power point of the lever, and using the distance from the handle 10 to the gripping end as a longer power arm, so that the operator only needs to apply a small amount of force to generate a large torque, which makes it more convenient to quickly assemble and disassemble in actual use.

[0062] The detector 25 provided by this invention integrates the complex backend motor control equipment and signal processing equipment into a single unit, enabling it to simultaneously perform control and processing functions. The detector 25 is equipped with a leakage magnetic signal input port 19 and a digital tube to display the measurement results in real time, facilitating human-machine interaction and data recording.

[0063] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves, characterized in that, Includes a housing and a magnetizing device and an automatic flaw detection assembly mounted on the housing, wherein: The magnetization device includes a magnetizer housing and a magnetizer. The magnetizer housing is mounted on the outer shell, and the magnetizer is mounted on the magnetizer housing. It is used to adsorb and magnetize the rebar sleeve assembly to be tested. The rebar sleeve assembly includes a rebar sleeve and two rebars connected to the rebar sleeve. The automatic flaw detection assembly includes a guide rail, a slider, a drive motor, a transmission mechanism, a probe shoe bracket, and a magnetic induction sensor. The length direction of the guide rail is consistent with the axial direction of the rebar sleeve. The slider is slidably mounted on the guide rail. The drive motor is connected to the slider through the transmission mechanism to drive the slider to move on the guide rail. The probe shoe bracket is fixed on the slider. The magnetic induction sensor is mounted on the probe shoe bracket to scan the surface of the rebar sleeve to obtain leakage magnetic signals as it moves with the slider.

2. The automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves according to claim 1, characterized in that, The outer casing includes a main casing and a handle. The handle is fixed to the main casing. A grip extends from one end of the main casing. The handle is located between the rebar sleeve and the grip, and the distance from the handle to the rebar sleeve is less than the distance from the handle to the grip, so that the outer casing can be rotated with the handle as a fulcrum to separate the magnetizer from the rebar sleeve. The automatic flaw detection component and the magnetization device are both installed inside the main housing. The main housing is provided with a motor signal input port and a leakage magnetic signal output port. The motor signal input port and the leakage magnetic signal output port are respectively connected to the drive motor and the magnetic induction sensor.

3. The automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves according to claim 1, characterized in that, It also includes a detector, which comprises a motor drive module, a data acquisition module, a signal processing module, a main control board, and a data display module. The motor drive module is electrically connected to the drive motor, and the data acquisition module is electrically connected to the magnetic induction sensor. It is used to acquire leakage magnetic signals and transmit them to the signal processing module. The signal processing module transmits the processed signal to the main control board. The main control board is used to perform logical analysis on the processed leakage magnetic signals and display the analysis results on the data display module.

4. The automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves according to claim 1, characterized in that, It also includes two photoelectric limit switches arranged along the length of the guide rail and both of them are fixed on the guide rail.

5. The automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves according to claim 4, characterized in that, The probe shoe bracket includes a sensor bracket and a detection plate. The magnetic induction sensor is mounted on the sensor bracket, and the detection plate is used to cooperate with the photoelectric limit switch.

6. The automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves according to claim 1, characterized in that, The magnetizer includes a semi-circular annular magnet and two armatures fixed on the semi-circular annular magnet. The two armatures are symmetrically arranged at both ends of the semi-circular annular magnet and are arranged along the axial direction of the semi-circular annular magnet. Each armature is provided with a V-shaped groove to fit against the rebar sleeve and to keep the rebar sleeve at a distance from the inner wall of the semi-circular annular magnet.

7. The automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves according to claim 1, characterized in that, A spacer is also installed on the magnetizer housing. The spacer is located between the steel sleeve and the magnetic induction sensor to protect the magnetic induction sensor. There is a gap between the spacer and the magnetizer to accommodate the probe shoe bracket and the magnetic induction sensor on the probe shoe bracket. The magnetic induction sensor is located between the spacer and the magnetizer.

8. The automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves according to claim 1, characterized in that, The transmission mechanism is a belt drive mechanism, and includes two pulleys and a belt connecting the two pulleys. One pulley is connected to the output shaft of the drive motor, and the other pulley is mounted on a support. The support is mounted on the housing, and the slider is mounted on the belt.

9. The automatic magnetic flux leakage flaw detection device for the internal connection quality of rebar sleeves according to claim 1, characterized in that, The magnetic induction sensor employs an induction coil or a Hall element, wherein: When the magnetic induction sensor uses an induction coil, the induction coil is composed of a coil winding made of multiple turns of wire tightly wound together, and when there are at least two induction coils, the number of layers of the coil winding of each induction coil is the same.

10. The flaw detection method of the automatic magnetic flux leakage flaw detection device for the internal connection quality of the reinforcing bar sleeve as described in any one of claims 1-9, characterized in that, Includes the following steps: 1) The magnetizer attracts the rebar sleeve assembly and magnetizes the rebar sleeve and the portion of each rebar located inside the rebar sleeve; 2) The drive motor drives the slider to move through the transmission mechanism. The slider drives the probe shoe bracket and the magnetic induction sensor to move along the length of the guide rail. During the movement of the magnetic induction sensor, the magnetic induction sensor scans the surface of the rebar sleeve to obtain the leakage magnetic signal. 3) The detector receives the leakage magnetic signal transmitted by the magnetic induction sensor to determine whether the two steel bars connected by the steel bar sleeve are abutting each other or whether there is a gap between the steel bar and the steel bar sleeve. 4) Separate the magnetizer from the rebar sleeve.

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