A magnetic flux leakage detector for staggered distribution of probes in variable diameter pipelines

Abstract

The present invention discloses a magnetic flux leakage detector with staggered probe distribution in a variable diameter pipeline, wherein a plurality of detection modules are evenly distributed in the circumferential direction outside the main body of the magnetic flux leakage detector, and each detection module is distributed in an x° sector shape in the circumferential direction. The detection module contracts and expands radially outside the main body, and a probe is provided on the detection module. The probe is distributed in a y° sector shape in the circumferential direction, y°>x°; the probes in two adjacent detection modules are staggered in the axial direction. When the magnetic flux leakage detector of the present invention is in the pipeline with the maximum detection diameter, the probe meets 100% signal coverage in the circumferential direction of the inner wall of the pipeline. When the magnetic flux leakage detector is in the pipeline with the minimum detection diameter, the staggered distributed probes are spatially displaced and overlapped in the axial direction of the pipeline, which effectively avoids the problem of mutual interference and extrusion of the probes in the circumferential direction, and meets the integrity detection requirements of the defect signal.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline magnetic flux leakage detection, in particular to a magnetic flux leakage detector with staggered distribution of probes in a variable diameter pipeline. Background Art

[0002] At present, the commonly used pipeline defect detection methods mainly include electromagnetic ultrasonic detection, piezoelectric ultrasonic detection and magnetic flux leakage detection. Among them, the magnetic flux leakage detection method installs magnetic sensitive elements on the magnetic flux leakage detector to pick up the pipeline leakage magnetic field and convert it into defect electrical signals. These signals are processed by filtering, amplification, analog-to-digital conversion, etc., so as to determine the defects. Therefore, its measurement results are relatively accurate and the operation is relatively simple, so it is widely used. However, in actual measurement work, the inner diameter of the pipeline is not uniform, there is a certain reduction in diameter, and it changes within a certain range along the pipeline. Most of the existing magnetic flux leakage detectors have a fixed single diameter and cannot fully adapt to different pipelines, so their application is limited. Summary of the invention

[0003] In order to overcome the defects in the above-mentioned prior art, the present invention provides a magnetic flux leakage detector with staggered distribution of probes in variable diameter pipelines, which can realize the detection of variable diameter pipelines and meet the integrity detection requirements of defect signals in pipelines of different diameters.

[0004] To achieve the above object, the present invention adopts the following technical solutions, including:

[0005] A magnetic flux leakage detector with staggered probe distribution in a variable diameter pipeline, comprising n detection modules uniformly distributed along the circumference outside the main body of the magnetic flux leakage detector, each detection module is distributed in an x° fan shape along the circumference, x°=360° / n;

[0006] The detection module performs contraction and expansion movements radially outside the main body; the detection module is provided with probes; the probes are distributed in a y° fan-shaped manner along the circumferential direction, y°>x°;

[0007] The probes in two adjacent detection modules are distributed in a staggered manner along the axial direction.

[0008] Preferably, the detection module comprises: a variable diameter support unit arranged on the main body, and a magnetic flux leakage detection unit connected to the variable diameter support unit and located outside the main body;

[0009] The variable diameter support unit is used to support the contraction and expansion movement of the magnetic flux leakage detection unit along the radial direction outside the main body; the probe is arranged on the magnetic flux leakage detection unit.

[0010] Preferably, the variable diameter support units are respectively provided at both ends of the magnetic flux leakage detector body along the axial direction, and the two variable diameter support units are respectively connected to the two ends of the magnetic flux leakage detection unit along the axial direction;

[0011] The variable diameter support unit includes a spring, a slider, and a connecting rod mechanism;

[0012] An axial groove is provided on the main body of the magnetic flux leakage detector, and a slider is located in the axial groove. The slider moves axially on the main body; one end of the spring is connected to the main body and is always in a compressed state, and the other end of the spring presses against the slider, which is connected to one end of a connecting rod mechanism, and the other end of the connecting rod mechanism is connected to the magnetic flux leakage detection unit; when the slider moves axially, the connecting rod mechanism drives the magnetic flux leakage detection unit to move radially outside the main body.

[0013] Preferably, the connecting rod mechanism comprises: a long connecting rod and a short connecting rod;

[0014] The slider is rotatably connected to one end of the long connecting rod, and the other end of the long connecting rod is rotatably connected to the leakage magnetic detection unit; one end of the short connecting rod is rotatably connected to the main body of the leakage magnetic detector; the other end of the short connecting rod is rotatably connected to the rod body of the long connecting rod.

[0015] Preferably, the other end of the short connecting rod is rotatably connected to the center of the long connecting rod, and the length of the short connecting rod is half the length of the long connecting rod.

[0016] Preferably, an adjustable limit block is provided on the main body of the magnetic flux leakage detector, one end of the spring presses against the limit block and the other end of the spring presses against the sliding block.

[0017] Preferably, the structure of the magnetic flux leakage detection unit is as follows:

[0018] The yoke is fixed by a yoke fixing support, the yoke fixing support is connected to the variable diameter support unit, permanent magnets are respectively arranged on both ends of the yoke along the axial direction, and steel brushes are arranged on the two permanent magnets, and the probe is located between the two permanent magnets on the yoke;

[0019] The steel brushes in each detection module are distributed in a x° fan shape along the circumferential direction, where x°=360° / n.

[0020] Preferably, the detection range of the magnetic flux leakage detector is as follows:

[0021] When the radial contraction of the detection module reaches the minimum, the steel brushes in the n detection modules are close to each other and the whole is cylindrical. At this time, the outer ring diameter formed by the steel brushes in the n detection modules is the minimum detection tube diameter d of the magnetic flux leakage detector;

[0022] When the radial expansion of the detection module reaches the maximum, the steel brushes in the n detection modules also expand radially, and the outer circumferential surfaces of the steel brushes are located on the circumferential surface of the same cylinder. At this time, the outer ring diameter formed by the steel brushes in the n detection modules is the maximum detection tube diameter D of the magnetic flux leakage detector;

[0023] Wherein, D=d*sin(x° / 2) / sin(y° / 2).

[0024] Preferably, eight detection modules are evenly distributed in the circumferential direction outside the main body of the magnetic flux leakage detector, each detection module is distributed in a 45° sector shape in the circumferential direction, and the probes are distributed in a 60° sector shape in the circumferential direction.

[0025] Preferably, a torsion spring part for adaptively fitting the inner wall of the pipeline is provided at the bottom of the probe.

[0026] The advantages of the present invention are:

[0027] (1) When the magnetic flux leakage detector of the present invention is in a non-reduced state and at the maximum detection diameter, the probe meets 100% signal coverage in the circumferential direction of the inner wall of the pipeline. When the magnetic flux leakage detector is in a reduced state and at the minimum detection diameter, the staggered distributed probes are spatially displaced and overlapped in the axial direction of the pipeline, effectively avoiding the problem of mutual interference and extrusion of the probes in the circumferential direction, and meeting the integrity detection requirements of the defect signal.

[0028] (2) The present invention applies a compressive force to the spring. When the magnetic flux leakage detector enters a pipeline with a large diameter from a pipeline with a small diameter, the slider drives the connecting rod mechanism to actively support the magnetic flux leakage detection unit to rebound and reset. The entire magnetic flux leakage detector expands radially, and automatic radial expansion from a small diameter to a large diameter can be achieved. Conversely, when the magnetic flux leakage detector enters a pipeline with a large diameter from a pipeline with a small diameter, the squeezing force of the inner wall of the pipeline passively squeezes the magnetic flux leakage detection unit to contract radially. The connecting rod mechanism squeezes the slider and the spring to move axially, so that the spring is further compressed, and the entire magnetic flux leakage detector contracts radially, and radial contraction from a large diameter to a small diameter can be achieved.

[0029] (3) The present invention applies a compressive force to the spring through a limit block, and the limit block can be adjusted on the magnetic flux leakage detector, thereby facilitating the adjustment of the compressive force applied to the spring, and further facilitating the adjustment of the measurement range adapted to the pipe diameter.

[0030] (4) The purpose of adding a short connecting rod to the connecting rod mechanism of the present invention is to enhance the stability of the connecting rod mechanism. If the short connecting rod is removed, the connecting rod mechanism at both ends is overall in a trapezoidal distribution, without parts support in the middle, and is prone to shaking left and right, making the leakage magnetic detection component full of uncertainty and causing large errors in the detection signal. After the short connecting rod is added to the present invention, the connecting rod mechanism at both ends of the axial direction is overall in a double herringbone distribution, and the short connecting rod swings in an arc around the center of the long connecting rod, so that one end of the long connecting rod moves axially and the other end moves radially, which greatly enhances the stability of the leakage magnetic detection component.

[0031] (5) The present invention installs a torsion spring component at the bottom of the probe, so that the probe can float up and down according to the change of the pipe diameter and adapt to different pipe wall curvatures, thereby adaptively fitting the inner wall of the pipe to ensure magnetic circuit saturation.

[0032] (6) The magnetic flux leakage detector of the present invention can meet the minimum detection tube diameter d by adjusting the initial size, and the measurement range of the tube diameter will also change to d~D accordingly, that is, d~d*sin(x° / 2) / sin(y° / 2). BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic structural diagram of a single detection module in the magnetic flux leakage detector of the present invention when it is contracted along the radial direction.

[0034] Figure 2 It is a schematic structural diagram of a single detection module in the magnetic flux leakage detector of the present invention when it is expanded in radial direction.

[0035] Figure 3 It is a schematic diagram of the fan-shaped distribution of the probe steel brush when a single detection module in the magnetic flux leakage detector of the present invention is contracted along the radial direction.

[0036] Figure 4 It is a schematic diagram of the fan-shaped distribution of the probe steel brush when a single detection module in the magnetic flux leakage detector of the present invention is expanded radially.

[0037] Figure 5 It is an overall schematic diagram of the magnetic flux leakage detector of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Depend on Figure 1-Figure 5 As shown, a magnetic flux leakage detector with staggered probe distribution in a variable diameter pipeline includes: n detection modules evenly distributed along the circumference outside the magnetic flux leakage detector body 13, each detection module is distributed in an x° fan shape along the circumference, x°=360° / n;

[0040] The detection module includes: a variable diameter support unit arranged on the magnetic flux leakage detector body 13, and a magnetic flux leakage detection unit connected to the variable diameter support unit and located outside the magnetic flux leakage detector body 13. The variable diameter support unit is used to support the contraction and expansion movement of the magnetic flux leakage detection unit in the radial direction outside the body 13. The magnetic flux leakage detection unit is provided with a probe 12; the probes 13 are all distributed in a y° fan-shaped manner along the circumferential direction, y°>x°, and the probes 12 in two adjacent detection modules are staggered along the axial direction.

[0041] In the present invention, the variable diameter support units are symmetrically arranged at both ends of the magnetic flux leakage detector body 13 along the axial direction, and the two variable diameter support units are respectively connected to the two ends of the magnetic flux leakage detection unit along the axial direction.

[0042] The variable diameter support unit comprises: a limit block 1, a spring 2, a slider 3, and a connecting rod mechanism;

[0043] An axial groove is provided on the magnetic flux leakage detector body 13, and the spring 2 and the slider 3 are located in the axial groove on the magnetic flux leakage detector body 13, so that the slider 3 moves axially; the limit block 1 is arranged on the magnetic flux leakage detector body 13 and can be adjusted in the axial direction, one end of the spring 2 presses against the limit block 1, and the spring 2 is always in a compressed state, and the other end of the spring 2 in the compressed state presses against the slider 3, and the slider 3 is connected to one end of the connecting rod mechanism, and the other end of the connecting rod mechanism is connected to the magnetic flux leakage detection unit; when the spring 2 and the slider 3 move axially, the connecting rod mechanism drives the magnetic flux leakage detection unit to move in a direction perpendicular to the axial direction outside the magnetic flux leakage detector body 13, that is, to move radially;

[0044] The connecting rod mechanism comprises: a long connecting rod 4 and a short connecting rod 5;

[0045] The slider 3 is rotatably connected to one end of the long connecting rod 4 through the connecting shaft 6, and the other end of the long connecting rod 4 is rotatably connected to the leakage magnetic detection unit through the connecting shaft 6; one end of the short connecting rod 5 is rotatably connected to the fixed support 8 of the leakage magnetic detector body 13 through the connecting shaft 6; the other end of the short connecting rod 5 is rotatably connected to the center of the long connecting rod 4 through the connecting shaft 6, and the length of the short connecting rod 5 is half the length of the long connecting rod 4.

[0046] The purpose of adding the short connecting rod 5 is to enhance the stability of the connecting rod mechanism. If the short connecting rod 5 is removed, the connecting rod mechanisms at both ends are arranged in a trapezoidal shape as a whole, and there is no part support in the middle, which is easy to shake left and right, making the leakage magnetic detection component full of uncertainty and causing large errors in the detection signal. After adding the short connecting rod 5, the connecting rod mechanisms at both ends of the axial direction are arranged in a double herringbone shape as a whole, and the short connecting rod 5 swings in an arc around the center of the long connecting rod 4, so that one end of the long connecting rod 4 moves axially and the other end moves radially, which greatly enhances the stability of the leakage magnetic detection component.

[0047] When the magnetic flux leakage detector enters the large-diameter pipeline from the small-diameter pipeline, the compression force applied to the spring 2 by the limit block 1 causes the slider 3 to drive the connecting rod mechanism to actively support the magnetic flux leakage detection unit to rebound and reset, and the entire magnetic flux leakage detector expands radially, realizing automatic radial expansion from the small diameter to the large diameter; conversely, when the magnetic flux leakage detector enters the small-diameter pipeline from the large-diameter pipeline, the squeezing force of the inner wall of the pipeline passively squeezes the magnetic flux leakage detection unit to shrink radially, and the connecting rod mechanism squeezes the slider and the spring to move axially, so that the spring is further compressed, and the entire magnetic flux leakage detector shrinks radially, realizing radial shrinkage from the large diameter to the small diameter.

[0048] The magnetic flux leakage detection unit includes: a yoke fixing support 7, a yoke 9, a permanent magnet 10, a steel brush 11, and a probe 12;

[0049] The yoke fixing support 7 is connected to the variable diameter support unit, the yoke 9 is fixed by the yoke fixing support 7, permanent magnets 10 are respectively provided at both ends of the yoke 9 in the axial direction, steel brushes 11 are provided on the two permanent magnets 10, and a detector probe 12 is provided on the yoke 9 between the two permanent magnets 10; both ends of the yoke fixing support 7 are rotatably connected to the long connecting rods 4 at the axial ends of the leakage magnetic detector body 13 through the connecting shaft 6.

[0050] In this embodiment, eight detection modules are evenly distributed along the circumference outside the magnetic flux leakage detector body 13, and each detection module is distributed in a 45° sector shape;

[0051] When the magnetic flux leakage detector enters the minimum diameter pipeline for detection, the compression amount of the spring 2 in each detection module is the maximum. At this time, the eight detection modules are close to each other, and the steel brushes in the eight detection modules are also close to each other, forming a cylindrical shape as a whole. At this time, the outer circle diameter formed by the steel brushes 11 in the eight detection modules is the minimum pipe diameter;

[0052] When the magnetic flux leakage detector enters the pipeline with the maximum diameter for detection, the compression amount of the spring 2 in each detection module is the minimum. At this time, the eight detection modules are expanded radially, and the outer circumferential surfaces of the eight detection modules are located on the circumferential surface of the same cylinder. The steel brush 11 and the probe 12 are still in close contact with the inner wall of the pipeline, meeting the detection requirements. At this time, the outer circle diameter formed by the steel brush 11 in the eight detection modules is the maximum pipe diameter.

[0053] Depend on Figure 5 As shown, the probes 12 in two adjacent detection modules are staggeredly distributed along the axial direction, and the probes in each detection module are distributed in a 60° sector shape, and coincide with the center line of the 45° sector shape distribution of the detection module, thereby ensuring that when the leakage magnetic detector enters the maximum diameter pipeline for detection, the probes 12 in the eight detection modules can achieve 100% signal coverage in the circumferential direction of the inner wall of the maximum diameter pipeline.

[0054] A torsion spring part is installed at the bottom of each probe 12, so that the probe 12 can float up and down according to the change of the pipe diameter, adapt to different pipe wall curvatures, and thus adaptively fit the inner wall of the pipe to ensure magnetic circuit saturation.

[0055] In a large-diameter pipeline, the structure and number of detection modules arranged on the leakage magnetic detector are determined according to the detection sensitivity of the probe, the measured diameter and the diameter variation range, so as to ensure that the signal coverage rate reaches 100% in the circumferential direction of the inner wall of the pipeline. In a small-diameter pipeline, since the leakage magnetic detector is compressed, the probe in the detection module also shrinks radially. Since the probes in two adjacent detection modules are staggered along the axial direction, although some probes overlap in the axial direction, it can effectively avoid the problem of mutual interference and extrusion of the probes in the circumferential direction when the leakage magnetic detector enters the small-diameter pipeline, and can achieve the continuous change of the diameter, but the probe always reaches 100% signal coverage rate in the circumferential direction of the inner wall of the pipeline. At the same time, under the action of the torsion spring at the bottom of the probe 12, the probe can be in good contact with the pipe wall in different postures, adapt to different pipe wall curvatures, and ensure magnetic circuit saturation. In this embodiment, when the leakage magnetic detector enters the minimum diameter pipeline, theoretically, the signal coverage rate of the leakage magnetic detector probe in the circumferential direction of the inner wall of the pipeline reaches 133%.

[0056] The magnetic flux leakage detector designed in this embodiment is required to meet the requirements of free diameter change and detection tasks in a 620mm-810mm variable diameter pipeline. The relevant dimensions of the magnetic flux leakage detector are calculated as follows:

[0057] The probe shrinks and expands in the radial direction, and its total arc length of 60° remains unchanged, and the curvature of the large diameter pipe wall is reduced. Each probe is adjusted by a torsion spring, and floats up and down according to the change of the pipe diameter to adaptively fit the inner wall of the pipe, adapt to the new curvature of the pipe wall, and ensure the saturation of the magnetic circuit. Since the eight detection modules are evenly distributed circumferentially on the outer side of the leakage magnetic detector body, in order to meet the requirement of 100% signal coverage of the probe on the inner wall of the pipe circumference when the pipe has the maximum diameter, the probe in each detection module must meet a circumferential coverage of at least 45° when detecting the pipe with the maximum diameter. It is calculated that the steel brushes in the eight detection modules are close to each other, and the outer ring diameter formed by the steel brushes in the eight detection modules is 620mm, which is the minimum detection pipe diameter; the compression amount of the spring in the detection module is the minimum, and when the eight detection modules are expanded radially to the maximum, the outer ring diameter formed by the steel brushes in the eight detection modules is:

[0058] 620*sin30° / sin22.5°=810mm.

[0059] When the size of the magnetic flux leakage detector changes, the measurement range of the magnetic flux leakage detector for the pipe diameter will also change. We take the minimum pipe measurement size as the initial size, that is, when the eight detection modules are fitted together, the probe detection coverage is 133%. At this time, the outer diameter of the steel brush is the minimum detection pipe diameter, represented by d. From the calculation formula, it can be obtained that the maximum measurement pipe diameter D is:

[0060] D=d*sin30° / sin22.5°

[0061] That is, D≈1.3d, so the magnetic flux leakage detector can change the value of d by adjusting the initial size, and the measurement range adapted to the pipe diameter will also change to d~1.3d accordingly.

[0062] The above are only preferred embodiments of the present invention and are 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 in the protection scope of the present invention.

Claims

1. A magnetic flux leakage detector with staggered distribution of probes in a variable diameter pipeline, characterized in that: It comprises n detection modules uniformly distributed along the circumference outside the main body (13) of the magnetic flux leakage detector, each detection module is distributed in the shape of a sector of x° along the circumference, where x°=360° / n; The detection module performs a contraction and expansion movement radially outside the main body (13); a probe (12) is provided on the detection module; the probes (12) are distributed in a y° fan-shaped manner along the circumferential direction, y°>x°; The probes (12) in two adjacent detection modules are distributed in a staggered manner along the axial direction; The detection module comprises: a variable diameter support unit arranged on the main body (13), and a magnetic flux leakage detection unit connected to the variable diameter support unit and located outside the main body (13); The variable diameter support unit is used to support the contraction and expansion movement of the magnetic flux leakage detection unit in the radial direction outside the main body (13); the probe (12) is arranged on the magnetic flux leakage detection unit; The structure of the magnetic flux leakage detection unit is as follows: The yoke (9) is fixed by a yoke fixing support (7), the yoke fixing support (7) is connected to the variable diameter support unit, permanent magnets (10) are respectively provided on both ends of the yoke (9) along the axial direction, and steel brushes (11) are provided on the two permanent magnets (10), and the probe (12) is located between the two permanent magnets (10) on the yoke (9); The steel brushes (11) in each detection module are distributed in a x° fan shape along the circumferential direction, where x°=360° / n; The detection range of the magnetic flux leakage detector is as follows: When the radial contraction amount of the detection module reaches the minimum, the steel brushes in the n detection modules are closely attached to each other and the whole is cylindrical. At this time, the outer ring diameter formed by the steel brushes (11) in the n detection modules is the minimum detection tube diameter d of the magnetic flux leakage detector; When the radial expansion amount of the detection module reaches the maximum, the steel brushes in the n detection modules also expand radially, and the outer circumferential surfaces of the steel brushes are located on the circumferential surface of the same cylinder. At this time, the outer ring diameter formed by the steel brushes (11) in the n detection modules is the maximum detection tube diameter D of the magnetic flux leakage detector; Where D = d*sin(x° / 2) / sin(y° / 2).

2. The magnetic flux leakage detector with staggered probe distribution in variable diameter pipeline according to claim 1, characterized in that: The variable diameter support units are respectively provided at two ends of the magnetic flux leakage detector body (13) along the axial direction, and the two variable diameter support units are respectively connected to the two ends of the magnetic flux leakage detection unit along the axial direction; The variable diameter support unit comprises a spring (2), a slider (3), and a connecting rod mechanism; An axial groove is provided on a main body (13) of the magnetic flux leakage detector, a slider (3) is located in the axial groove, and the slider (3) moves axially on the main body (13); one end of the spring (2) is connected to the main body (13) and is always in a compressed state, the other end of the spring (2) presses against the slider (3), the slider (3) is connected to one end of a connecting rod mechanism, and the other end of the connecting rod mechanism is connected to a magnetic flux leakage detection unit; when the slider (3) moves axially, the connecting rod mechanism drives the magnetic flux leakage detection unit to move radially outside the main body (13).

3. The magnetic flux leakage detector with staggered probe distribution in variable diameter pipeline according to claim 2, characterized in that: The connecting rod mechanism comprises: a long connecting rod (4) and a short connecting rod (5); The slider (3) is rotatably connected to one end of the long connecting rod (4), and the other end of the long connecting rod (4) is rotatably connected to the magnetic flux leakage detection unit; one end of the short connecting rod (5) is rotatably connected to the main body (13) of the magnetic flux leakage detector; and the other end of the short connecting rod (5) is rotatably connected to the rod body of the long connecting rod (4).

4. The magnetic flux leakage detector with staggered probe distribution in variable diameter pipeline according to claim 2, characterized in that: The other end of the short connecting rod (5) is rotatably connected to the center of the long connecting rod (4), and the length of the short connecting rod (5) is half the length of the long connecting rod (4).

5. A magnetic flux leakage detector with staggered probe distribution in a variable diameter pipeline according to claim 2, 3 or 4, characterized in that: An adjustable limit block (1) is provided on the main body (13) of the magnetic flux leakage detector, one end of a spring (2) presses against the limit block (1) and the other end of the spring (2) presses against a slider (3).

6. The magnetic flux leakage detector with staggered probe distribution in variable diameter pipeline according to claim 1, characterized in that: Eight detection modules are evenly distributed along the circumference of the main body (13) of the magnetic flux leakage detector, each detection module is distributed in a 45° sector shape along the circumference, and the probes (12) are distributed in a 60° sector shape along the circumference.

7. The magnetic flux leakage detector with staggered probe distribution in variable diameter pipeline according to claim 1, characterized in that: The bottom of the probe (12) is provided with a torsion spring part for adaptively fitting the inner wall of the pipeline.

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