Eddy current and magnetic flux leakage combined detection probe

Abstract

The utility model discloses an eddy current and magnetic flux leakage combined detection probe, and relates to the technical field of pipeline flaw detection, in particular to an eddy current and magnetic flux leakage combined detection probe which comprises a ferromagnetic pipeline, and the ferromagnetic pipeline is internally provided with a combined detection probe body composed of an eddy current excitation coil, a Hall element, an eddy current detection coil and a permanent magnet. The eddy current excitation coil is arranged at the center of the joint detection probe, and the Hall elements are annularly arranged to form a circular ring with the outer diameter slightly smaller than the inner diameter of the ferromagnetic pipeline. According to the eddy current and magnetic flux leakage combined detection probe, the permanent magnet is arranged, so that the eddy current and magnetic flux leakage combined detection probe has the effect of avoiding interference of eddy current detection signal defects on interpretation caused by non-uniform magnetic conductivity; the eddy current and magnetic flux leakage combined detection probe has the effect of improving the detection sensitivity.

Description

Technical Field

[0001] This utility model relates to the field of pipeline flaw detection technology, specifically to a combined eddy current and magnetic flux leakage detection probe. Background Technology

[0002] Currently, the detection of ferromagnetic pipes mainly adopts eddy current or magnetic leakage detection methods. However, both methods have certain limitations. Eddy current detection is more sensitive to longitudinal defects in pipes, but less sensitive to circumferential defects. Moreover, due to the uneven magnetic permeability of the material, ferromagnetic pipes will generate strong interference signals, which will affect the interpretation of defect signals. Therefore, when performing conventional eddy current detection on ferromagnetic pipes (1), magnetic saturation treatment of the pipes is required. However, when detecting in-service pipes, the testing site often does not have the conditions to perform magnetic saturation treatment on ferromagnetic pipes. Therefore, the application of conventional eddy current detection technology to the detection of in-service ferromagnetic pipes is limited. Magnetic leakage detection is more sensitive to circumferential defects in pipes, but less sensitive to longitudinal defects. Utility Model Content

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a combined eddy current and magnetic flux leakage detection probe, which solves the problems mentioned in the background section.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, this utility model is implemented through the following technical solution: a combined eddy current and leakage magnetic flux detection probe, comprising a ferromagnetic pipe, wherein the ferromagnetic pipe is internally equipped with a combined detection probe consisting of an eddy current excitation coil, a Hall element, an eddy current detection coil, and a permanent magnet. The eddy current excitation coil is one coil located at the center of the combined detection probe. Several Hall elements are arranged circumferentially to form a ring with an outer diameter slightly smaller than the inner diameter of the ferromagnetic pipe. Two eddy current detection coils are symmetrically distributed on both sides of the eddy current excitation coil. Two permanent magnets are distributed in front of and behind the combined detection probe.

[0007] Preferably, the permanent magnet is a ring with an outer diameter slightly smaller than the inner diameter of the ferromagnetic pipe, and the Hall element is located in the middle of the two permanent magnets.

[0008] Preferably, when the magnetic lines of force generated by the permanent magnet pass through the ferromagnetic pipe, it is equivalent to magnetic saturation treatment of the pipe, which can eliminate the influence of uneven magnetic permeability of the pipe on the eddy current detection effect.

[0009] Preferably, when an alternating current is applied to the eddy current excitation coil, an alternating magnetic field is generated, which excites the eddy current detection coil to generate an alternating current. Since the two eddy current detection coils have the same number of turns and opposite winding directions, the electromotive forces formed between the two eddy current detection coils are equal in magnitude but opposite in direction. If there is no metal missing in the ferromagnetic channel at the two eddy current detection coils, the two electromotive forces cancel each other out and no eddy current signal is generated. Conversely, if there is a metal missing in the ferromagnetic channel at one of the two eddy current detection coils, the two electromotive forces cannot cancel each other out and an eddy current signal is generated.

[0010] Preferably, the leakage magnetic field generated by the permanent magnet passing through the wall of the ferromagnetic pipe is detected by a Hall element, and the two eddy current detection coils detect the ferromagnetic pipe by the difference in electromotive force generated in the two coils. The two detection methods detect the ferromagnetic pipe from different angles, which can effectively detect its damage.

[0011] Preferably, the eddy current excitation coil, Hall element, eddy current detection coil, and permanent magnet are all fixed on a plastic frame. When this combined detection probe is used to detect small-diameter ferromagnetic pipes, it can be moved by pulling the cable by hand.

[0012] This invention provides a combined eddy current and magnetic flux leakage detection probe, which has the following advantages:

[0013] 1. This eddy current and magnetic leakage flux combined detection probe, through the setting of permanent magnets, enables the eddy current and magnetic leakage flux combined detection probe to avoid the interference of eddy current detection signal defects caused by uneven magnetic permeability. By installing permanent magnets that can magnetize ferromagnetic pipes at both the front and rear of the probe to perform magnetic saturation treatment on the pipes, the pipes are in a state of uniform magnetic permeability when being detected, thereby avoiding the problem of defect signal interpretation caused by uneven magnetic permeability.

[0014] 2. This eddy current and magnetic flux leakage combined detection probe, through the coordinated arrangement of eddy current excitation coil, eddy current detection coil, Hall element and permanent magnet, has the effect of improving detection sensitivity. The detection probe is equipped with eddy current detection coils with opposite winding directions and equal number of turns and permanent magnet. Through magnetic flux leakage detection and eddy current detection, it can realize multi-angle detection of ferromagnetic pipes, and can simultaneously and sensitively detect longitudinal and circumferential defects in pipes, thereby improving detection sensitivity. Attached Figure Description

[0015] Figure 1 This is a structural schematic diagram of the main view of this utility model.

[0016] In the diagram: 1. Ferromagnetic pipe; 2. Eddy current excitation coil; 3. Hall element; 4. Eddy current detection coil; 5. Permanent magnet. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0018] Please see Figure 1 This utility model provides a technical solution: a combined eddy current and magnetic leakage detection probe, including a ferromagnetic pipe 1. Inside the ferromagnetic pipe 1, a combined detection probe is installed, consisting of an eddy current excitation coil 2, a Hall element 3, an eddy current detection coil 4, and a permanent magnet 5. The eddy current excitation coil 2, Hall element 3, eddy current detection coil 4, and permanent magnet 5 are all fixed to a plastic frame. When used to detect small-diameter ferromagnetic pipes 1, this combined detection probe can be moved by manually pulling a cable. One eddy current excitation coil 2 is located at the center of the combined detection probe. Several Hall elements 3 are arranged circumferentially to form a ring with an outer diameter slightly smaller than the inner diameter of the ferromagnetic pipe 1. Two eddy current detection coils 4 are symmetrically distributed on both sides of the eddy current excitation coil 2. Two permanent magnets 5 are distributed in front of and behind the combined detection probe. The permanent magnet 5 is a ring with an outer diameter slightly smaller than the inner diameter of the ferromagnetic pipe 1. The Hall element 3 is located in the middle of the two permanent magnets 5. When the magnetic lines of force generated by the permanent magnet 5 pass through the ferromagnetic pipe 1, it is equivalent to magnetically saturating the pipe, which can eliminate the influence of the non-uniform magnetic permeability of the pipe on the eddy current detection effect. When the eddy current excitation coil 2 is energized with alternating current, it generates an alternating magnetic field, which excites the eddy current detection coil 4 to generate an alternating current. Since the two eddy current detection coils 4 have the same number of turns and opposite winding directions, the electromotive forces formed between the two eddy current detection coils 4 are equal in magnitude but opposite in direction. If there is no metal missing in the ferromagnetic pipe 1 at the two eddy current detection coils 4, the two electromotive forces cancel each other out and no eddy current signal is generated. Conversely, if there is a metal missing in the ferromagnetic pipe 1 at one of the two eddy current detection coils 4, the two electromotive forces cannot cancel each other out and an eddy current signal is generated. The leakage magnetic field generated by the permanent magnet 5 through the pipe wall of the ferromagnetic pipe 1 is detected by the Hall element 3. The two eddy current detection coils 4 detect the ferromagnetic pipe 1 through the difference in electromotive forces generated in the two coils. The two detection methods detect the ferromagnetic pipe 1 from different angles and can effectively detect its damage.

[0019] In use, this combined detection probe is based on the eddy current detection probe used inside the pipeline. The probe is lengthened and two annular permanent magnets 5, symmetrical to the Hall element 3 and eddy current excitation coil 2, are installed at the front and rear. The Hall element 3 receives the magnetic signals generated by the two permanent magnets 5 and the electromotive force difference generated by the two eddy current detection coils 4 to perform multi-angle analysis of the ferromagnetic pipeline 1. Specifically, the Hall element 3 receives and analyzes the leakage magnetic field generated by the permanent magnets 5 at pipe wall defects, and the two eddy current detection coils 4 analyze the defects at the pipe wall of the ferromagnetic pipeline 1 through the electromotive force difference generated in the two coils. The longitudinal defects of the ferromagnetic pipeline 1 are particularly relevant to the eddy current detection. The signal interference generated by the measuring coil 4 is relatively large. Therefore, receiving and analyzing the signal fluctuations of the eddy current detection coil 4 can sensitively detect the longitudinal defects of the ferromagnetic pipe 1. When the magnetic field generated by the permanent magnet 5 encounters the circumferential defects of the ferromagnetic pipe 1, the magnetic field fluctuations are large. Therefore, receiving and analyzing the magnetic field fluctuations generated by the permanent magnet 5 can sensitively detect the circumferential defects of the ferromagnetic pipe 1. Since the detection probe uses both methods to monitor simultaneously, it can achieve the effect of simultaneously and sensitively monitoring circumferential and longitudinal defects. The permanent magnets 5 at the front and rear of the probe can also magnetically saturate the pipe to be inspected by the eddy current detection coil 4, making the detection results of the eddy current detection coil 4 more accurate.

[0020] In summary, this combined eddy current and magnetic flux leakage detection probe achieves magnetic saturation of the ferromagnetic pipe 1 by installing permanent magnets 5 at both the front and rear of the probe, ensuring that the pipe is in a state of uniform magnetic permeability during inspection. This avoids the problem of defect signal interpretation caused by uneven magnetic permeability. Since the probe simultaneously installs eddy current detection coils 4 with opposite winding directions and the same number of turns as the permanent magnets 5, it can perform multi-angle inspection of the ferromagnetic pipe 1 through magnetic flux leakage detection and eddy current detection. It can simultaneously and sensitively detect longitudinal and circumferential defects in the pipe, thereby improving detection sensitivity.

[0021] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A combined eddy current and magnetic flux leakage detection probe, comprising a ferromagnetic pipe (1), characterized in that: The ferromagnetic pipe (1) is equipped with a joint detection probe consisting of an eddy current excitation coil (2), a Hall element (3), an eddy current detection coil (4), and a permanent magnet (5). The number of eddy current excitation coils (2) is one, which is arranged at the center of the joint detection probe. The number of Hall elements (3) is several, which are arranged in a ring along the circumference to form a ring with an outer diameter slightly smaller than the inner diameter of the ferromagnetic pipe (1). The number of eddy current detection coils (4) is two, which are symmetrically distributed on both sides of the eddy current excitation coils (2). The number of permanent magnets (5) is two, which are distributed in front of and behind the joint detection probe.

2. The eddy current and leakage magnetic flux combined detection probe according to claim 1, characterized in that: The permanent magnet (5) is a ring with an outer diameter slightly smaller than the inner diameter of the ferromagnetic pipe (1), and the Hall element (3) is located in the middle of the two permanent magnets (5).

3. The combined eddy current and magnetic leakage detection probe according to claim 1, characterized in that: When the magnetic lines of force generated by the permanent magnet (5) pass through the ferromagnetic pipe (1), it is equivalent to magnetic saturation treatment of the pipe, which can eliminate the influence of the non-uniform magnetic permeability of the pipe on the eddy current detection effect.

4. The eddy current and leakage magnetic flux combined detection probe according to claim 1, characterized in that: When an alternating current is applied to the eddy current excitation coil (2), an alternating magnetic field is generated, which excites the eddy current detection coil (4) to generate an alternating current. Since the two eddy current detection coils (4) have the same number of turns and opposite winding directions, the electromotive force formed between the two eddy current detection coils (4) is equal in magnitude but opposite in direction. If there is no metal missing in the ferromagnetic pipe (1) at the two eddy current detection coils (4), the two electromotive forces cancel each other out and no eddy current signal is generated. Conversely, if there is a metal missing in the ferromagnetic pipe (1) at one of the two eddy current detection coils (4), the two electromotive forces cannot cancel each other out and an eddy current signal is generated.

5. The eddy current and leakage magnetic flux combined detection probe according to claim 1, characterized in that: The leakage magnetic field generated by the permanent magnet (5) through the wall of the ferromagnetic pipe (1) is detected by the Hall element (3). The two eddy current detection coils (4) detect the ferromagnetic pipe (1) by the difference in electromotive force generated in the two coils. The two detection methods detect the ferromagnetic pipe (1) from different angles, which can effectively detect its damage.

6. The eddy current and leakage magnetic flux combined detection probe according to claim 1, characterized in that: The eddy current excitation coil (2), Hall element (3), eddy current detection coil (4) and permanent magnet (5) are all fixed on the plastic frame. When the combined detection probe is used to detect small-diameter ferromagnetic pipes (1), it can be moved by pulling the cable by hand.

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