A magnetic yoke for a fillet weld, a detection device and a detection method

Abstract

The present application relates to the technical field of magnetic particle flaw detection, and particularly relates to a magnetic yoke for fillet weld, a detection device and a detection method. The present application provides a detection device for fillet weld, which comprises a magnetic yoke, the magnetic yoke comprises a first trapezoidal ring and a second trapezoidal ring, the first trapezoidal ring and the second trapezoidal ring are connected through a cross beam; the first trapezoidal ring and the second trapezoidal ring are provided with openings on the same side and the short sides are arranged on the same side, the straight line distance between the long sides of the first trapezoidal ring and the second trapezoidal ring is less than the straight line distance between the short sides; the openings of the short sides and the long sides of the first trapezoidal ring and the second trapezoidal ring are provided with magnetic poles; the current comprises full-wave rectified current and alternating current, the short sides of the first trapezoidal ring and the second trapezoidal ring are connected with different currents, and the long sides are connected with different currents; two sides of the first trapezoidal ring and the second trapezoidal ring are connected with different currents. The present application aims to solve the technical problem that there is no magnetic yoke and detection device for detecting fillet weld defects in the prior art.

Description

Technical Field

[0001] This invention relates to the technical field of magnetic particle testing, and particularly to a magnetic yoke, testing device, and testing method for fillet welds. Background Technology

[0002] Heavy-duty pressure equipment is characterized by its large size, complex structure, and harsh operating conditions, posing significant risks of leakage and explosion. It is also prone to various defects during use, thus requiring regular inspection. Due to the high risk associated with heavy-duty pressure equipment, magnetic particle testing is typically used to conduct 100% coverage inspection of its internal and external welds. Taking a large spherical tank with a volume of 3000 cubic meters or more as an example, to achieve 100% magnetic particle testing of the tank's internal surface, preparatory work such as shutting down the tank, replacing toxic gases and liquids, and erecting scaffolding inside and outside the tank is necessary. Then, maintenance personnel climb the scaffolding, carrying testing equipment to conduct the inspection. A magnetic field is applied to the inspection location, and a suitably prepared magnetic suspension is sprayed. Defects are then identified visually using a black light. This method is not only time-consuming and expensive, but also exposes inspectors inside the tank to the threats of working at heights, exposure to toxic substances, and high temperatures.

[0003] To overcome this problem, some magnetic particle inspection robots have been successfully applied in engineering projects in China. However, existing magnetic particle inspection robots can only perform magnetic particle inspection on defects in butt welds where there are no obstacles to movement, and cannot inspect fillet welds on the inner surface of pipe fittings. For fillet welds on pipe fittings of heavy pressure equipment, magnetic particle inspection of the inner surface is essential. Therefore, scaffolding still needs to be erected, and workers still need to climb the scaffolding to manually grind the weld before conducting another inspection. This renders the previously omitted scaffolding step meaningless, making it difficult to significantly reduce working time and costs while ensuring personal safety during the operation. Therefore, to effectively protect the health and safety of inspection personnel and create a new "machine-for-human" operation mode in hazardous inspection scenarios, it is urgent to overcome the key challenge of magnetic particle inspection of the inner surface of fillet welds on pipe fittings of heavy pressure equipment.

[0004] Currently, the perpendicular arrangement of cross-yoke electromagnets is used for flaw detection. Chinese utility model patent CN205449885U, published on August 10, 2016, discloses an automatic magnetic particle inspection device for the inner wall of pipes. It includes a walking unit, a power mechanism, and a detection unit. The power mechanism includes a servo motor, a gearbox, a front rotating shaft, and a rear rotating shaft. The servo motor, through the gearbox, can drive the front and rear rotating shafts to rotate respectively. The rear rotating shaft is connected to the walking unit and transmits power. The detection unit is fixedly mounted on the front rotating shaft and can rotate along it as a whole. The detection unit is equipped with casters. When the power mechanism drives the walking unit through the rear rotating shaft, the casters allow the detection unit to follow the entire device and move in a straight line along the pipe wall for monitoring. When the power mechanism drives the rotation through the front rotating shaft, the entire device stops at the position to be inspected in the pipe, and only the detection unit moves in a circle along the pipe wall for monitoring with the help of the casters. The perpendicular arrangement of the cross-yoke electromagnets in this patent makes it difficult to use in fillet welds.

[0005] Chinese invention patent application CN115841905A, published on March 24, 2023, discloses a phase compensation method for non-90° cross magnetic yokes and its application, belonging to the field of magnetic particle inspection technology. When the included angle of the cross magnetic yoke is 90°, two alternating currents with a 90° phase difference are used for excitation, resulting in the major and minor axes of the effective magnetization range being equal, thus forming a perfect circle. When the included angle of the cross magnetic yoke is not 90°, the phase difference between the two alternating currents is adjusted to make the major and minor axes equal, forming a perfect circle through phase compensation. By compensating for the phase difference of the cross magnetic yoke, a perfectly circular rotating magnetic field can be formed under any pipe diameter, achieving optimal flaw detection results. This eliminates the problem of distortion in the rotating magnetic field generated by the cross magnetic yoke due to the adjustable chamfer of the magnetic yoke probe with different structures and shapes. This allows the cross magnetic yoke to be truly applied to the flaw detection of various pipe welds and fillet welds. Although the patent application can be applied to fillet welds, most defects in fillet welds are parallel to the weld direction, requiring a shorter magnetic yoke circuit for longitudinal magnetization.

[0006] Therefore, it is necessary to propose a magnetic yoke, detection device, and detection method for fillet welds to solve the problems raised in the background art. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a magnetic yoke, detection device and detection method for fillet welds, which aims to solve the technical problem that there is no good magnetic yoke and detection device for detecting defects in fillet welds in the prior art.

[0008] To achieve the above objectives, in a first aspect, the present invention proposes a magnetic yoke for fillet welds, comprising a first trapezoidal ring and a second trapezoidal ring, which are connected by a crossbeam; the first and second trapezoidal rings have openings on the same side and their short sides are also on the same side, and the straight-line distance between the long sides of the first and second trapezoidal rings is less than the straight-line distance between their short sides; magnetic poles are provided at the openings of the short and long sides of the first and second trapezoidal rings; the current includes full-wave rectified current and alternating current, with different currents connected to the short sides of the first and second trapezoidal rings and different currents connected to their long sides; different currents are connected to the two sides of the first and second trapezoidal rings respectively; during measurement, the fillet weld is always located between the first and second trapezoidal rings.

[0009] Preferably, the short side of the first trapezoidal ring and the long side of the second trapezoidal ring are connected to the same full-wave rectified power supply, and the long side of the first trapezoidal ring and the short side of the second trapezoidal ring are connected to the same alternating current.

[0010] Preferably, the first trapezoidal ring and the second trapezoidal ring are right-angled trapezoids, and the waist edges of the first trapezoidal ring and the second trapezoidal ring are perpendicular to the fillet weld.

[0011] Preferably, the full-wave rectified current and the alternating current are divided into two equal paths by the same current, with the peak value and frequency being the same; both the first trapezoidal ring and the second trapezoidal ring are wound with coils; one end of the coil of the first trapezoidal ring is electrically connected to the alternating current, and the other end is electrically connected to the short side of the second trapezoidal ring through a wire; one end of the coil on the long side of the second trapezoidal ring is electrically connected to the full-wave rectified current, and the other end is electrically connected to the short side of the first trapezoidal ring through a wire; the crossbeam divides the coils into four independent sections.

[0012] Preferably, during measurement, the two magnetic poles of the short sides of the first trapezoidal ring and the second trapezoidal ring overlap the inner wall of the pipe, while the other two magnetic poles contact the inner wall of the heavy-duty pressure equipment body; a detachable curvature adapter block is provided at one end of the magnetic pole.

[0013] Preferably, the first trapezoidal ring and the second trapezoidal ring are provided with elastic telescopic frames on their short and long sides, and wheels are provided on the elastic telescopic frames.

[0014] To achieve the above objectives, in a second aspect, the present invention provides a detection device, comprising a circumferential motion operation platform, a retractable control lever disposed on the circumferential motion operation platform, and a suspension device disposed on the retractable control lever, wherein the magnetic yoke described above is disposed on the suspension device.

[0015] Preferably, a nozzle, a video detection system, and a black light are sequentially arranged inside the magnetic yoke; the liquid sprayed by the nozzle is transported through a magnetic suspension liquid delivery pipe; the control box communicates and controls the spraying of the nozzle, and the pressurization system is used to control the spraying pressure of the sprayed liquid.

[0016] Preferably, the circumferential motion operation platform includes a ferromagnetic disk, conical drive wheels evenly arranged below the ferromagnetic disk, a handwheel assembly arranged above the ferromagnetic disk, and a joystick mounting bracket for mounting the handwheel assembly. The joystick mounting bracket is arranged on the magnetic disk, and a guide rail is provided on the joystick mounting bracket. The handwheel assembly moves along the guide rail, and a telescopic joystick is provided on the handwheel assembly.

[0017] To achieve the above objectives, in a second aspect, the present invention proposes a detection method for inspecting fillet welds using the aforementioned detection device, comprising the following steps:

[0018] a. Grind and remove rust from the fillet welds to be inspected;

[0019] b. Set appropriate curvature adapter blocks on the magnetic yoke;

[0020] c. The magnetic yoke is transported to the position to be tested through the circumferential motion operation platform, and the magnetic poles of the magnetic yoke are respectively in contact with the inner wall of the pipe and the inner wall of the heavy pressure equipment body;

[0021] d. Defect detection is performed by connecting the current of the magnetic yoke. Longitudinal magnetization and axial magnetization are achieved in one AC cycle. Data of more than ten alternating longitudinal and circumferential magnetizations are collected during the application time of the magnetic suspension.

[0022] e. After disconnecting the current, move the circumferentially yoke to the next position to continue defect detection;

[0023] f. Repeat steps d and e until the entire weld has been inspected, then retrieve the inspection device.

[0024] Compared with the prior art, the beneficial effects of the magnetic yoke, detection device, and detection method for fillet welds provided by the present invention are as follows:

[0025] This invention employs a three-dimensional structure with two magnetic poles overlapping the inner wall of the connecting pipe, while the other two magnetic poles contact the inner wall of the heavy-duty pressure equipment. The two planes are essentially perpendicular, and the area of ​​the magnetic poles is relatively small compared to the detection surface, essentially a point. Therefore, through a three-dimensional combined magnetic yoke suspension device, the angle and posture can be adjusted to ensure close contact with both the connecting pipe and the container's inner wall. Unlike the typical square shape of the fillet weld, the combined magnetic yoke core is a trapezoid that tapers towards the center of the connecting pipe. For larger fillet welds, the trapezoidal hypotenuse can be essentially perpendicular to the weld, resulting in better magnetization compared to a square structure. This invention utilizes a three-dimensional structure with a combined magnetic yoke core, employing the spatial arrangement of four magnetic poles and different current patterns to simultaneously achieve longitudinal and circumferential magnetization through instantaneous changes in the magnetic poles. This rapid alternation between longitudinal and circumferential magnetization is equivalent to four magnetic circuits acting simultaneously, creating a superimposed magnetic field and ensuring effective magnetization.

[0026] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a structural diagram of the auxiliary part of the present invention.

[0028] Figure 2 This is a structural diagram of the detection part of the present invention.

[0029] Figure 3 This is a diagram of the circumferential motion operation platform of the present invention.

[0030] Figure 4 This is a three-dimensional structural diagram of the combined magnetic yoke core.

[0031] Figure 5 This includes the winding structure diagram and circuit illustration.

[0032] Figure 6 This is a diagram showing the distribution of the longitudinal magnetization magnetic field during the positive half-cycle of alternating current.

[0033] Figure 7 This is a diagram showing the distribution of the circumferential magnetization magnetic field during the negative half-cycle of alternating current.

[0034] Figure 8 This diagram illustrates the contact between the combined magnetic yoke core and the inner wall.

[0035] Figure 9 This is a top view of the circumferential motion operation platform of the present invention.

[0036] In the diagram: 1. Magnetization detection device; 2. Circumferential motion operating platform; 3. Cable; 4. Magnetic suspension delivery pipe; 5. Control box; 6. Pressurization system; 7. Fixing plate; 8. Suspension device; 9. Magnetic yoke; 10. Nozzle; 11. Video detection system; 12. Black light; 13. Telescopic joystick; 14. Conical drive wheel; 15. Ferromagnetic disk; 16. Handwheel assembly; 17. Encoder cable; 18. Displacement encoder; 19. Conical rolling bearing assembly; 20. Guide rail; 21. Joystick mounting bracket; 22. Conical drive wheel and conical rolling bearing assembly fastening threaded hole group; 23. Drive stepper motor; 30. First trapezoidal ring; 31. Second trapezoidal ring; 32. Crossbeam; 33. Elastic telescopic frame; 34. Wheel. Detailed Implementation

[0037] 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. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0038] In the description of this invention, it should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to or indirectly connected to the other element.

[0039] In the description of this invention, it should be noted that the terms "center," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0040] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] See Figure 1 and Figure 2 This invention provides a magnetic particle inspection device for the inner surface of fillet welds on heavy-duty pressure equipment pipe seats, comprising an inspection section and an auxiliary section. The auxiliary section includes a circumferential motion operating platform 2, a cable 3, a magnetic suspension liquid delivery pipe 4, a control box 5, and a magnetic suspension liquid stirring and pressurizing system 6, which collectively assist the magnetization inspection device 1. The inspection section includes a fixed plate 7, a three-dimensional combined magnetic yoke suspension device 8, a three-dimensional combined magnetic yoke 9, a nozzle 10, a video inspection system 11, a black light 12, and a retractable joystick 13. The retractable joystick 13 is mounted on the circumferential motion operating platform 2, the suspension device 8 is mounted on the retractable joystick 13, and the magnetic yoke 9 is mounted on the suspension device 8. The nozzle 10, video inspection system 11, and black light 12 are sequentially arranged within the magnetic yoke 9; the liquid sprayed by the nozzle 10 is transported through the magnetic suspension liquid delivery pipe 4; the control box 5 controls the spraying of the nozzle 10, and the pressurizing system 6 controls the spraying pressure of the liquid sprayed by the nozzle 10.

[0042] Specifically, the magnetic suspension spraying device, consisting of nozzle 10 and magnetic suspension delivery pipe 4, is installed at the outer end of the magnetic pole of the fixed plate, facing the corner weld. An electric valve is installed in the magnetic suspension spraying device, and the spraying time is controlled by a control box. A black light 12 and a video detection system 11 are installed under the middle crossbeam of the three-dimensional combined magnetic yoke 9, forming a certain intersection angle to enhance the observation effect. The magnetic suspension stirring and pressurizing system 6, the circumferential motion operating platform 2, and the control box 5 are located outside the pressure-bearing equipment and are connected to the magnetization detection device 1, which is placed inside the equipment, via the magnetic suspension delivery pipe 4 and cable 3. The cable 3 is energized to achieve magnetization operation, and the magnetic suspension delivery pipe 4 and the electric valve switch enable magnetic suspension spraying operation.

[0043] Furthermore, such as Figure 3 and Figure 9As shown, the circumferential motion operation platform 2 includes a ferromagnetic disk 15, conical drive wheels 14 evenly arranged below the ferromagnetic disk 15, a handwheel assembly 16 arranged above the ferromagnetic disk 15, and a joystick mounting bracket 21 for mounting the handwheel assembly 16. The joystick mounting bracket 21 is mounted on the magnetic disk 15 and has a guide rail 20. The handwheel assembly 16 moves along the guide rail 20 and has a retractable joystick 13. The conical drive wheels 14 are located near the joystick because the joystick exerts greater pressure on the disk, resulting in greater driving friction. The circumferential motion operation platform 2 also includes an encoder cable 17, a displacement encoder 18, a conical rolling bearing assembly 19, a threaded hole group 22 for fastening the conical drive wheels and rolling bearing assembly (one of which has a common-specification position scale), and a drive stepper motor 23. The main function of the circumferential motion operating platform is to support the retractable control lever 13 to enable the detection device to move circumferentially along the weld seam. At the same time, the disc can also block light to ensure the fluorescence detection effect. The circumferential motion operating platform includes two detection modes: manual detection and automatic detection. In manual detection mode, the circumferential motion is operated by the handwheel assembly 16. Four conical wheels support the platform, and one conical wheel is equipped with an encoder to read the movement position. In automatic detection mode, the two conical drive wheels 14 move automatically through the control box 5.

[0044] The retractable joystick can be used to raise or lower the magnetization detection device. The joystick's retractability is mainly due to the fact that some equipment connections and external pipelines only have space for removing a valve. First, the magnetization detection device is moved along the guide rail 20 to near the center of the connection using the joystick mounting bracket 21. Then, the retractable joystick lower button is pressed to lower the magnetization detection device 1. Finally, the joystick mounting bracket 21 is adjusted to bring the magnetization detection device 1 to the detection position. To retract it, the magnetization detection device 1 is first moved to near the center of the connection, and then the up button is pressed to retract it.

[0045] Control box 5 controls the entire inspection operation. In automatic inspection mode, control box 5 can control magnetization, magnetic suspension spraying, and circumferential movement of the magnetic yoke. With appropriate programming of magnetization, magnetic suspension spraying, and circumferential movement of the magnetic yoke, pressing the inspection button can achieve fully automatic inspection of the entire fillet weld. In manual inspection mode, control box 5 can control magnetization and magnetic suspension spraying. After manually adjusting to the appropriate circumferential position, pressing the inspection button completes one inspection. This process is repeated until the entire weld is inspected.

[0046] In order to achieve longitudinal and circumferential magnetization and improve the accuracy of weld inspection, the present invention improves the magnetic yoke. The specific structure of the magnetic yoke is described below.

[0047] See Figure 4-9The magnetic yoke of the present invention is used for fillet welds. It is a three-dimensional composite magnetic yoke, which is not a typical square but a trapezoid that shrinks towards the center of the nozzle. For larger nozzle fillet welds, the hypotenuse of the trapezoid can be basically perpendicular to the weld. Compared with the square structure, it can achieve a better magnetization effect. The magnetic yoke includes a first trapezoidal ring 30 and a second trapezoidal ring 31, connected by a crossbeam 32. The first and second trapezoidal rings 30 and 31 have openings on the same side and their short sides are also on the same side. The straight-line distance between the long sides of the first and second trapezoidal rings 30 and 31 is less than the straight-line distance between their short sides. Magnetic poles are provided at the openings of the short and long sides of the first and second trapezoidal rings 30 and 31. The current includes full-wave rectified current and alternating current. Different currents are connected to the short sides of the first and second trapezoidal rings 30 and 31, and different currents are connected to the long sides. Different currents are connected to the two sides of the first and second trapezoidal rings 30 and 31 respectively. During measurement, the fillet weld is always located between the first and second trapezoidal rings 30 and 31. A shared magnetic circuit (i.e., the "crossbeam" section) utilizes the spatial arrangement of the four magnetic poles and different current patterns to achieve longitudinal and circumferential magnetization in a short time through instantaneously changing magnetic poles. Considering that most defects are parallel to the weld direction, a shorter magnetic circuit for longitudinal magnetization of the yoke is required (e.g., A and B, D and C directly form a magnetic circuit without passing through the crossbeam), resulting in a relatively stronger magnetic field, which is more conducive to detecting longitudinal defects parallel to the weld direction. For ease of description, A, B, C, and D refer to the locations of the magnetic poles.

[0048] The short side of the first trapezoidal ring 30 and the long side of the second trapezoidal ring 31 are connected to the same full-wave rectified current, and the long side of the first trapezoidal ring 30 and the short side of the second trapezoidal ring 31 are connected to the same alternating current. The first trapezoidal ring 30 and the second trapezoidal ring 31 are right-angled trapezoids, and their waist sides are perpendicular to the fillet weld. The full-wave rectified current and the alternating current are divided into two equal paths by the same current, with the same peak value and frequency. Both the first trapezoidal ring 30 and the second trapezoidal ring 31 are wound with coils. One end of the coil of the first trapezoidal ring 30 is electrically connected to the alternating current, and the other end is electrically connected to the short side of the second trapezoidal ring 31 through a wire. One end of the coil on the long side of the second trapezoidal ring 31 is electrically connected to the full-wave rectified current, and the other end is electrically connected to the short side of the first trapezoidal ring 30 through a wire. The crossbeam 32 divides the coils into four independent sections.

[0049] Specifically, the winding structure of the three-dimensional combined magnetic yoke 9 is as follows: Figure 5As shown, the same current is divided into two equal paths: one is a unidirectional full-wave rectifier, and the other is an alternating current (AC). Both have the same peak value and frequency. A and C are symmetrically connected to the full-wave rectifier, with pole A always being the N pole and pole C always being the S pole. B and D are connected to the AC, and their magnetic pole characteristics change with the direction of the current. During the positive half-cycle of the AC current, D is the N pole and B is the S pole; during the negative half-cycle of the AC current, D is the S pole and B is the N pole. The direction of the magnetic field lines and the magnetic flux density of the two-phase magnetic circuits passing through the beam are the vector sum of the two-phase magnetic circuits. During the positive half-cycle of the alternating current, A and D are the N poles, and B and C are the S poles, thus forming four pairs of magnetic yokes: A and B, A and C, D and B, and D and C. The magnetic fields formed by the A and B and D and C pairs of magnetic yokes in the weld area of ​​the workpiece are spaced apart by a certain distance, are basically unaffected by each other, and form a longitudinal magnetic field that is basically perpendicular to the weld. The magnetic fields formed by the A and C and D and B pairs of magnetic yokes in the weld area of ​​the workpiece overlap, and according to the principle of vector superposition, their combined magnetic field is a longitudinal magnetic field that is basically perpendicular to the weld. During the positive half-cycle of the alternating current, the magnetic field distribution formed by the four pairs of magnetic yokes is as follows: Figure 6 As shown, this belongs to longitudinal magnetization. Similarly, during the negative half-cycle of the alternating current, the magnetic field distribution formed by the four pairs of yokes is as follows. Figure 7 As shown, this belongs to circumferential magnetization. Therefore, longitudinal magnetization and circumferential magnetization are achieved separately within one alternating current cycle. During the application time of the magnetic suspension, there are dozens of alternating longitudinal and circumferential magnetizations, which can ensure the simultaneous detection of defects in different directions.

[0050] During measurement, the two magnetic poles of the short sides of the first trapezoidal ring 30 and the second trapezoidal ring 31 overlap on the inner wall of the connecting pipe, while the other two magnetic poles contact the inner wall of the heavy-duty pressure-bearing equipment body; a detachable curvature adapter block is provided at one end of the magnetic pole. The three-dimensional combined magnetic yoke 9 contacts the inner wall as follows... Figure 8 As shown, two magnetic poles overlap the inner wall of the connecting pipe, while the other two magnetic poles contact the inner wall of the heavy-duty pressure equipment. The two planes are essentially perpendicular, and the area of ​​the magnetic poles is relatively small compared to the detection surface, essentially a point. Therefore, the three-dimensional combination magnetic yoke suspension device 8 can be used to adjust the angle and posture to ensure close contact with the connecting pipe and the inner wall of the container, respectively. Curvature adapter blocks are installed at the contact magnetic poles of the magnetic yoke core. These curvature adapter blocks can be easily installed and removed. For pressure equipment with different curvature ranges, this invention provides corresponding curvature adapter blocks to achieve close contact between the magnetic poles and the inner wall of the connecting pipe.

[0051] To facilitate movement, a structure designed for easy mobility was added. Specifically, this is a three-dimensional combined magnetic yoke 9, with four magnetic poles connected to the wall by elastic telescopic frames 33 and wheels 34. When energized, the magnetic poles maintain close contact with the wall due to magnetic force. When de-energized, there is no magnetic force, and the magnetic poles detach from the wall under the elastic force of the telescopic frames, allowing the wheels to directly contact the wall, facilitating device movement. One-way wheels are installed on the magnetic poles contacting the inner wall of the connecting pipe, while universal wheels are installed on the magnetic poles contacting the inner wall of the main body, as their movement is not linear. Elastic telescopic frames 33 are provided on the short and long sides of the first trapezoidal ring 30 and the second trapezoidal ring 31, and wheels 34 are mounted on these frames. Universal wheels can be selected for practical use.

[0052] The following steps are included in the inspection of fillet welds using a magnetic particle inspection device for the inner surface of fillet welds on heavy-duty pressure equipment pipe fittings:

[0053] (1) The sensitivity of the magnetic particle detection device of the present invention is verified. If the verification result meets the requirements, it can be used in actual use.

[0054] (2) Grind and remove rust from the fillet weld to meet the testing requirements. Rust will affect the test results.

[0055] (3) Pre-adjust the detection device, such as installing the corresponding curvature adapter block, and fully stirring the magnetic suspension and adding sufficient air pressure.

[0056] (4) Adjust the conical drive wheel and conical rolling bearing assembly fastening threaded hole group 22 according to the inner diameter of the pipe, so that the four conical drive wheels 14 of the circumferential motion operating platform are in contact with the inner corner of the pipe flange.

[0057] (5) Lower the magnetic powder detection device by the retractable control lever, move the control lever mounting bracket 21, so that the universal wheels of the four magnetic poles of the three-dimensional combined magnetic yoke 9 contact the inner wall of the pipe and the inner wall of the body respectively.

[0058] Perform the inspection operation according to the procedure requirements. If using the automatic inspection method, pressing the inspection button completes the entire fillet weld inspection without manual intervention. If using the manual inspection method, rotate the handwheel to adjust to the appropriate circumferential position according to the displacement encoder, press the inspection button to complete one inspection, and repeat this process until the entire weld is inspected. The automatic inspection method will be described below. The magnetic yoke is energized, and its four magnetic poles are attracted to the equipment. Two magnetic poles overlap the inner wall of the connecting pipe, and the other two magnetic poles contact the inner wall of the heavy-duty pressure equipment body. Longitudinal and circumferential magnetization are achieved within one AC current cycle. During the application of the magnetic suspension, dozens of alternating longitudinal and circumferential magnetizations ensure simultaneous detection of defects in different directions.

[0059] (6) Disconnect the current. The handwheel assembly will automatically rotate to a suitable angle and then drive the magnetic yoke to rotate, reconnecting the power. Longitudinal magnetization and circumferential magnetization are achieved respectively within one AC cycle. During the application time of the magnetic suspension, there are dozens of alternating longitudinal and circumferential magnetizations. This process is repeated until the entire weld is inspected.

[0060] (7) After the test is completed, press the up button to retract the magnetic particle detection device. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A magnetic yoke for a fillet weld, characterized by: The application relates to a magnetic yoke, which comprises a first trapezoidal ring (30) and a second trapezoidal ring (31), wherein the first trapezoidal ring (30) and the second trapezoidal ring (31) are connected through a cross beam (32); the first trapezoidal ring (30) and the second trapezoidal ring (31) are provided with openings on the same side and short sides arranged on the same side; the straight line distance between the long sides of the first trapezoidal ring (30) and the second trapezoidal ring (31) is smaller than the straight line distance between the short sides; the openings of the short sides and the long sides of the first trapezoidal ring (30) and the second trapezoidal ring (31) are provided with magnetic poles; the current comprises full-wave rectified current and alternating current; the short side of the first trapezoidal ring (30) and the long side of the second trapezoidal ring (31) are connected with the full-wave rectified current, and the long side of the first trapezoidal ring (30) and the short side of the second trapezoidal ring (31) are connected with the alternating current; the full-wave rectified current and the alternating current are equally divided into two paths by the same current, and the peak value and the frequency are the same; the first trapezoidal ring (30) and the second trapezoidal ring (31) are both provided with coils; one end of the coil of the first trapezoidal ring (30) is electrically connected with the alternating current, and the other end is electrically connected with the short side of the second trapezoidal ring (31) through a wire; one end of the coil of the long side of the second trapezoidal ring (31) is electrically connected with the full-wave rectified current, and the other end is electrically connected with the short side of the first trapezoidal ring (30) through a wire; in the positive half cycle of the alternating current, four pairs of magnetic yokes form a longitudinal magnetization magnetic field; in the negative half cycle of the alternating current, four pairs of magnetic yokes form a circumferential magnetization magnetic field; two edges of the first trapezoidal ring (30) and the second trapezoidal ring (31) are respectively connected with different currents; and the corner joint is located between the first trapezoidal ring (30) and the second trapezoidal ring (31) during measurement.

2. A magnetic yoke for a fillet weld as defined in claim 1, wherein: The first trapezoidal ring (30) and the second trapezoidal ring (31) are right-angle trapezoids, and the waist edges of the first trapezoidal ring (30) and the second trapezoidal ring (31) are perpendicular to the corner joint.

3. A magnetic yoke for a fillet weld as defined in claim 1, wherein: The cross beam (32) divides the coil into four independent parts.

4. A magnetic yoke for a fillet weld as defined in claim 1, wherein: During measurement, two magnetic poles of the short sides of the first trapezoidal ring (30) and the second trapezoidal ring (31) are overlapped on the inner wall of the connecting pipe, and the other two magnetic poles are in contact with the inner wall of the body of the heavy pressure-bearing equipment; a detachable curvature adapting block is arranged at one end of the magnetic pole.

5. A magnetic yoke for a fillet weld as defined in claim 1, wherein: Elastic telescopic supports (33) are arranged on the short sides and the long sides of the first trapezoidal ring (30) and the second trapezoidal ring (31), and wheels (34) are arranged on the elastic telescopic supports.

6. A detection device characterized by: The application further relates to a magnetic yoke (9) as claimed in any one of claims 1-5, which is arranged on a circumferential motion operation platform (2), a telescopic operating rod (13) and a suspension device (8) arranged on the telescopic operating rod (13).

7. A device for detecting a weld according to claim 6, characterized in that: A nozzle (10), a video detection system (11) and a black light lamp (12) are sequentially arranged in the magnetic yoke (9); the liquid sprayed by the nozzle (10) is transported through a magnetic suspension liquid conveying pipe (4); a control box (5) is used for controlling the spraying of the nozzle (10), and a pressurizing system (6) is used for controlling the spraying pressure of the spraying liquid of the nozzle (10).

8. A device for detecting a weld according to claim 7, characterized in that: The circumferential movement operation platform (2) comprises a ferromagnetic disc (15), a conical driving wheel (14) arranged uniformly below the ferromagnetic disc (15), a hand wheel assembly (16) arranged above the ferromagnetic disc (15), and a joystick mounting bracket (21) for mounting the hand wheel assembly (16), wherein the joystick mounting bracket (21) is arranged on the magnetic disc (15), a guide rail (20) is arranged on the joystick mounting bracket (21), the hand wheel assembly (16) moves along the guide rail (20), and a telescopic joystick (13) is arranged on the hand wheel assembly (16).

9. A method of detection, characterized by: The detection device of claim 8 is used for angle weld detection, comprising the following steps: a. polishing and rust removal of the angle weld to be detected; b. arranging appropriate curvature adapting blocks on the magnetic yoke (9); c. conveying the magnetic yoke (9) to the position to be detected by the circumferential movement operation platform (2), and making the magnetic poles of the magnetic yoke (9) contact the inner wall of the pipe and the inner wall of the heavy pressure-bearing equipment body, respectively; d. turning on the current of the magnetic yoke (9) to detect defects, realizing longitudinal magnetization and axial magnetization, respectively, in one AC cycle, and collecting more than ten data of the alternating action of longitudinal magnetization and circumferential magnetization in the magnetic suspension application time; e. after turning off the current, moving the magnetic yoke (9) to the next position to continue the defect detection; f. repeating steps d and e until the entire weld is detected, and recovering the detection device.

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