Omnidirectional defect detection electromagnetic induction probe and defect detection device

Abstract

The utility model discloses an omnidirectional defect detection electromagnetic induction probe and a defect detection device, the probe comprises two excitation parts and two receiving parts, two serially connected excitation coils of the excitation parts are suitable for generating same primary electromagnetic fields with opposite directions; the winding directions of two receiving coils of the receiving component are opposite, and the two receiving coils are suitable for forming induction signals according to an induced secondary electromagnetic field; the axis directions of the exciting coil and the receiving coil are parallel; a first direction and a second direction which are orthogonal are defined perpendicular to the axis direction, and a first plane perpendicular to the first direction is defined; the two excitation parts are close to each other and arranged side by side in the first direction, and the first plane is located between the two excitation parts and has the same axis distance with the two excitation coils; the two receiving parts are close to each other in the second direction side by side. The axes of the two receiving coils are located on the first plane. The probe and the defect detection device can improve the detection sensitivity of longitudinal defects.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic induction probes, in particular to an omnidirectional defect detection electromagnetic induction probe and a defect detection device. Background Art

[0002] An electromagnetic induction probe generally consists of an excitation component, a receiving component, and associated signal processing circuitry. Both components consist of a coil wrapped around a magnetic core. The excitation coil generates an alternating magnetic field, which interacts with the material being tested. The receiving coil senses a secondary magnetic field generated by the material being tested, which is caused by eddy currents within the material. Existing electromagnetic induction probes have good detection sensitivity for transverse defects perpendicular to their scanning direction, but have low sensitivity for longitudinal defects parallel to the scanning direction. Utility Model Content

[0003] The purpose of the present invention is to overcome the above-mentioned defects or problems existing in the background technology and to provide an omnidirectional defect detection electromagnetic induction probe and a defect detection device, which can improve the detection sensitivity of longitudinal defects.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0005] Technical Solution 1: An omnidirectional defect detection electromagnetic induction probe, comprising: two excitation components, each of which comprises a spirally wound excitation coil; the two excitation coils are connected in series and are suitable for generating the same but opposite primary electromagnetic fields; two receiving components, each of which comprises a spirally wound receiving coil; the two receiving coils are wound in opposite directions and are suitable for forming an induction signal based on the induced secondary electromagnetic field; the axial directions of the excitation coil and the receiving coil are parallel; a first direction and a second direction that are orthogonal to the axial direction are defined, and a first plane that is perpendicular to the first direction is defined; the two excitation components are arranged side by side close to each other along the first direction, the first plane is located between the two excitation components, and is at the same distance from the axes of the two excitation coils; the two receiving components are arranged side by side close to each other along the second direction, and the axes of the two receiving coils are located in the first plane.

[0006] Technical solution 2 based on technical solution 1: define a second plane perpendicular to the axial direction, and the connecting lines formed by connecting the intersection points of the second plane and the axes of the two excitation coils and the two receiving coils in sequence are rhombuses, and the two receiving coils are located on the long diagonal line of the rhombus.

[0007] Technical solution three based on technical solution one: define a second plane perpendicular to the axis direction, and the connecting line formed by connecting the intersection points of the second plane with the axes of the two excitation coils and the two receiving coils in sequence is a square.

[0008] Technical solution 4 based on technical solution 3: the excitation coil and the receiving coil are wound with copper wire of the same nature.

[0009] Technical solution five based on technical solution four: the diameters of the two receiving coils are equal, and the diameters of the excitation coil and the receiving coil are equal.

[0010] Technical Solution 6 based on Technical Solution 5: The excitation component also includes a cylindrical excitation magnetic core, and the receiving component also includes a cylindrical receiving magnetic core; the excitation coil is wound on the circumferential surface of the excitation magnetic core, and on the detection end side of the excitation component, the end of the excitation magnetic core is exposed by a preset length of the excitation coil; the receiving coil is wound on the circumferential surface of the receiving magnetic core, and on the induction end side of the receiving component, the end of the receiving magnetic core is exposed by a preset length of the receiving coil.

[0011] Technical solution seven based on technical solution six: the excitation magnetic core and the receiving magnetic core are both ferrite cores.

[0012] Technical solution eight based on technical solution seven: also includes a shell, which is cylindrical and surrounds the two excitation components and the two receiving components, and its outer surface is provided with detection marks at positions corresponding to the two excitation components; the shell is provided with an opening for exposing the detection end of the excitation component and the receiving end of the receiving component.

[0013] Technical solution nine based on technical solution eight: the shell is made of aluminum alloy.

[0014] In addition, the utility model also provides technical solution ten: a defect detection device, which includes an alternating power supply and a signal processor, and also includes an omnidirectional defect detection electromagnetic induction probe as described in any one of technical solutions one to nine, the probe is connected to the alternating power supply and sends an induction signal to the signal processor.

[0015] From the above description of the present invention, it can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0016] Technical solution one provides an omnidirectional defect detection electromagnetic induction probe, which includes two excitation components and two receiving components, wherein the excitation component includes an excitation coil, and the two excitation coils are connected in series. When connected to an alternating power supply, the two excitation coils can generate primary electromagnetic fields of the same intensity but opposite directions. When the primary electromagnetic field approaches the material to be measured, the eddy current of the material to be measured forms a secondary electromagnetic field. The receiving coils in the two receiving components will generate an induction signal according to the secondary electromagnetic field, and output the induction signal to the corresponding signal processor. The surface defect of the material to be measured can be judged according to the change of the induction signal.

[0017] In this technical solution, the positions of the excitation component and the receiving component are specially limited; wherein, the two excitation coils are arranged side by side in a first direction, which enables the two excitation coils to form a neutral characteristic surface at the position of the first plane. At the same time, the two excitation coils can each detect defects within a part of the range. The combination of the two enables the probe to have omnidirectional detection capability. This wider range of detection capability enables the probe to have a greater probability of falling into the detection range of the probe even if there are longitudinal defects on the surface of the material being tested, thereby improving the detection capability of longitudinal defects; however, this layout of the excitation component will make the receiving component difficult to configure. In this technical solution, the two receiving coils are specifically arranged at the position of the first plane. At this time, the primary electromagnetic fields generated by the two excitation coils are basically offset at the position of the plane, thereby reducing the electromagnetic interference generated by the excitation coil on the receiving coil, improving the inductive sensitivity of the receiving coil to the secondary electromagnetic field, and having the effect of noise suppression and signal enhancement; at the same time, the two receiving coils are arranged to play the role of differential detection. The positions of the two are symmetrical with each other, which can improve the consistency of the induced signal and help reduce the detection error caused by changes in the probe posture and other external factors, thereby improving the reliability of the detection results.

[0018] In technical solution two, the positional relationship between the two excitation coils and the two receiving coils is defined. The two excitation coils are positioned closer together, which can provide higher sensitivity for longitudinal defect detection when the excitation signal strength is low. The two receiving coils are positioned farther apart. In addition to reducing the interference of the excitation coils on the receiving coils, it can also increase the detection range of the probe, which helps the probe detect longitudinal defects.

[0019] In technical solution three, the positional relationship between the two excitation coils and the two receiving coils is defined. The square relative position ensures that the positions of the two primary electromagnetic fields formed during the detection process correspond to each other, and the strength of the generated induced signals is also consistent, thereby reducing the detection error caused by changes in the probe position and improving the detection accuracy.

[0020] In technical solution four, the use of copper wires of the same properties can ensure that the resistance, inductance and other electrical characteristics of the coils match, thereby ensuring consistency in the generation and reception of electromagnetic fields.

[0021] In technical solution five, the excitation coil and receiving coil with equal diameters make the generated and induced electromagnetic fields have similar spatial distribution characteristics, ensuring that the electromagnetic coupling efficiency between the excitation and receiving coils is maximized, which is conducive to improving the detection accuracy of the probe.

[0022] In technical solution six, the cylindrical magnetic core can enhance the magnetic field strength and concentration of the coil; at the same time, by exposing a preset length of the magnetic core at the detection end and the sensing end, when the magnetic core contacts the surface of the material being measured, the coil is still a certain distance away from the surface of the material being measured, thereby making the interaction range between the primary electromagnetic field and the material being measured wider, and the corresponding receiving coil can induce a larger range of secondary electromagnetic fields, thereby improving the detection capability of the probe by optimizing the distribution of the electromagnetic field.

[0023] In technical solution seven, the ferrite core has the characteristics of high magnetic permeability and low loss, which can effectively increase the magnetic field strength of the coil while reducing energy loss in high-frequency current.

[0024] In Technical Solution 8, a cylindrical shell is provided, and detection marks are provided on the shell corresponding to the positions of the two excitation components. The detection marks can conveniently determine the positions of the excitation components inside the probe. These two positions correspond to the parts with higher sensitivity in the detection range, which can conveniently allow staff to determine the scanning direction and posture of the probe.

[0025] In technical solution nine, aluminum alloy is used as the shell material to reduce the impact of external electronic noise.

[0026] Technical solution ten provides a defect detection device, which adopts the above-mentioned probe and has omnidirectional defect detection capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A schematic diagram of a portion of the structure of an omnidirectional defect detection electromagnetic induction probe provided by an embodiment of the present utility model;

[0029] Figure 2 A schematic cross-sectional view of an omnidirectional defect detection electromagnetic induction probe provided by an embodiment of the present utility model;

[0030] Figure 3 for Figure 1 Schematic diagram of the detection status of the probe.

[0031] Description of main reference numerals:

[0032] Excitation component 1; excitation coil 2; receiving component 3; receiving coil 4; first plane 5; excitation core 6; receiving core 7; housing 8; detection mark 9. DETAILED DESCRIPTION

[0033] The following will be combined with the accompanying 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 preferred embodiments of the present invention and should not be regarded as excluding other embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] In the claims, description and the above-mentioned drawings of the present utility model, unless otherwise clearly defined, the use of terms such as "first", "second" or "third" is to distinguish different objects rather than to describe a specific order.

[0035] In the claims, specification and the above-mentioned drawings of the present utility model, unless otherwise expressly defined, directional words, such as the terms "center", "transverse", "longitudinal", "horizontal", "vertical", "top", "bottom", "inside", "outside", "up", "down", "front", "back", "left", "right", "clockwise", "counterclockwise" and the like, indicating directions or positional relationships are based on the directions and positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the specific protection scope of the present utility model.

[0036] In the claims, specification and the above drawings of the present utility model, unless otherwise clearly defined, if the terms "fixed connection" or "fixed connection" are used, they should be understood in a broad sense, that is, any connection method without any displacement relationship and relative rotation relationship between the two parties, that is to say, including non-detachable fixed connection, detachable fixed connection, integral connection and fixed connection through other devices or elements.

[0037] In the claims, description and drawings of the present utility model, if the terms "include", "have" and their variations are used, they are intended to mean "including but not limited to".

[0038] Example 1

[0039] Embodiment 1 of the present invention provides an omnidirectional defect detection electromagnetic induction probe, which is used to detect defects on the surface of the material being tested. In conjunction with a corresponding alternating power supply and a signal processor, the waveform changes can be displayed on an oscilloscope in real time during the detection process, and the defect conditions on the surface of the material being tested can be judged based on the waveform changes.

[0040] The probe mainly includes two excitation components 1 , two receiving components 3 and a shell 8 .

[0041] Reference Figure 1 In the two excitation components 1 of the probe, each excitation component 1 includes a spirally wound excitation coil 2 and a cylindrical excitation core 6. The excitation coil 2 is wound around the circumferential surface of the excitation core 6, and on the detection end side of the excitation component 1, the end of the excitation core 6 is exposed by a preset length of the excitation coil 2; and the two excitation coils 2 are connected in series and are suitable for generating the same and opposite-direction primary electromagnetic fields.

[0042] And, refer to Figure 1 The axes of the two excitation coils 2 are parallel, defining an axis direction, and a first direction and a second direction orthogonal to each other are defined according to the axis direction. The axis direction of the excitation coil 2 refers to the spiral extension direction of the excitation coil 2 .

[0043] Reference Figure 3 , defining a first plane 5 perpendicular to the first direction. The two excitation components 1 are arranged side by side close to each other along the first direction. The first plane 5 is located between the two excitation components 1 and is at the same distance from the axes of the two excitation coils 2.

[0044] Reference Figure 1 In the two receiving parts 3 of the probe, each receiving part 3 includes a spirally wound receiving coil 4 and a cylindrical receiving magnetic core 7. The receiving coil 4 is wound on the circumferential surface of the receiving magnetic core 7, and on the inductive end side of the receiving part 3, the end of the receiving magnetic core 7 is exposed by a preset length of the receiving coil 4.

[0045] And, refer to Figure 1 , the axis directions of the two receiving coils 4 are parallel, and the axis directions of the two receiving coils 4 are parallel to the axis directions of the two exciting coils 2, so Figure 1 The axis direction in FIG represents the axis direction of the two receiving coils 4 and the two exciting coils 2. The two receiving components 3 are arranged side by side close to each other along the second direction, and the axes of the two receiving coils 4 are located in the first plane 5.

[0046] The above-mentioned omnidirectional defect detection electromagnetic induction probe includes two excitation components 1 and two receiving components 3, wherein the excitation component 1 includes an excitation coil 2, and the two excitation coils 2 are connected in series. When connected to an alternating power supply, the two excitation coils 2 can generate a primary electromagnetic field of the same intensity but opposite direction. When the primary electromagnetic field approaches the material to be measured, the eddy current of the material to be measured forms a secondary electromagnetic field. The receiving coils 4 in the two receiving components 3 will generate an induction signal according to the secondary electromagnetic field, and output the induction signal to the corresponding signal processor. The surface defect of the material to be measured can be judged according to the change of the induction signal.

[0047] In this technical solution, the positions of the excitation component 1 and the receiving component 3 are specially limited; wherein, the two excitation coils 2 are arranged side by side in a first direction, which enables the two excitation coils 2 to form a neutral characteristic surface at the position of the first plane 5, and at the same time, the two excitation coils 2 can respectively detect defects within a part of the range, and the combination of the two enables the probe to have omnidirectional detection capability. This larger range of detection capability enables the probe to have a greater probability of falling into the detection range of the probe when it sweeps over the surface of the material to be tested, even if there are longitudinal defects on the surface of the material to be tested, thereby improving the detection capability of longitudinal defects; however, the excitation of this layout Component 1 will make the receiving component 3 difficult to configure. In this technical solution, the two receiving coils 4 are specially set at the position of the first plane 5. At this time, the primary electromagnetic fields generated by the two excitation coils 2 are basically offset at this plane position, thereby reducing the electromagnetic interference generated by the excitation coil 2 on the receiving coil 4, and improving the inductive sensitivity of the receiving coil 4 to the secondary electromagnetic field, which has the effect of noise suppression and signal enhancement; two receiving coils 4 are set at the same time to play the role of differential detection. The positions of the two are symmetrical to each other, which can improve the consistency of the induced signal, and help reduce the detection error caused by changes in the probe posture and other external factors, and improve the reliability of the detection results.

[0048] Specifically, the end of the excitation core 6 is exposed to a preset length of the excitation coil 2, and the end of the receiving core 7 is exposed to a preset length of the receiving coil 4. The preset length here can be set according to the actual size of the excitation core 6 and the size of the excitation coil 2. When the sizes of the two are larger, the preset length is relatively reduced, and when the sizes of the two are smaller, the preset length is relatively increased. The relative increase and relative decrease here refer to the conclusions drawn by comparing the length with the sizes of the two. Among them, the cylindrical magnetic core can enhance the magnetic field strength and concentration of the coil; at the same time, by exposing the magnetic core of the preset length at the detection end and the sensing end, when the magnetic core contacts the surface of the material to be measured, the coil is still a certain distance away from the surface of the material to be measured, thereby making the interaction range between the primary electromagnetic field and the material to be measured wider, and the corresponding receiving coil 4 can induce a larger range of secondary electromagnetic fields, thereby improving the detection capability of the probe by optimizing the distribution of the electromagnetic field.

[0049] In this embodiment, the excitation coil 2 and the receiving coil 4 are wound with copper wire of identical properties. Identical properties refer to the copper wire being of the same material, diameter, and shape. Using identical copper wire ensures that the coils' resistance, inductance, and other electrical properties match, thereby ensuring consistency during electromagnetic field generation and reception.

[0050] At the same time, the diameters of the two receiving coils 4 are equal, and the diameters of the excitation coil 2 and the receiving coil 4 are equal. When copper wires of the same properties are used, the diameters of the receiving coil 4 and the excitation coil 2 are equal, and it can be considered that the sizes of the two are completely consistent. At the same time, since the two excitation coils 2 are to form the same and opposite primary electromagnetic fields, the number of turns of the two excitation coils 2 is the same. For similar reasons, the two receiving coils 4 are to ensure the consistency of the induced signals, so the number of turns of the two receiving coils 4 is also the same. However, the number of turns of the excitation coil 2 and the number of turns of the receiving coil 4 may be inconsistent, and the specific number of turns of the two can be adjusted according to actual conditions, which is not limited here.

[0051] In this embodiment, the excitation core 6 and the receiving core 7 are both ferrite cores. Ferrite cores have the characteristics of high magnetic permeability and low loss, which can effectively increase the magnetic field strength of the coil and reduce energy loss in high-frequency current.

[0052] In addition, refer to Figure 2 , a second plane perpendicular to the axis direction is defined, and the lines formed by sequentially connecting the second plane with the focal points of the axes of the two excitation coils 2 and the two receiving coils 4 are squares. Specifically, the axes of the two excitation coils 2 and the axes of the two receiving coils 4 can be regarded as the centers of circles in the cross-sectional schematic diagram, and connecting these four centers in sequence can form a square. The relative positions of the squares ensure that the positions of the two primary electromagnetic fields formed during the detection process correspond to each other, and the strength of the generated induced signals is also consistent, thereby reducing the detection error caused by changes in the probe position and improving the detection accuracy.

[0053] Reference Figure 2 A housing 8 is disposed outside the aforementioned excitation component 1 and receiving component 3. The housing 8 is cylindrical and surrounds the excitation components 1 and the receiving components 3. Detection marks 9 are provided on its outer surface at positions corresponding to the positions of the excitation components 1. The housing 8 has openings for exposing the detecting end of the excitation component 1 and the receiving end of the receiving component 3. The housing 8 protects the excitation component 1 and the receiving component 3, and the openings enhance detection sensitivity.

[0054] The detection mark is located on the outer surface of the housing. It can be a raised protrusion or a piece of paper attached to the housing, as long as it serves as an identification mark. Two detection marks are provided, one corresponding to each of the two excitation components. In this embodiment, the two detection marks are located on the extended line connecting the axes of the two excitation coils. Detection marks 9 provided on the housing 8 facilitate the determination of the position of the excitation component 1 within the probe. These two positions correspond to the more sensitive portions of the detection range, making it easy for personnel to determine the probe's sweep direction and posture.

[0055] In this embodiment, the housing 8 is made of aluminum alloy. Using aluminum alloy as the material of the housing 8 can reduce the influence of external electronic noise.

[0056] Example 2

[0057] Example 2 provides an omnidirectional defect detection electromagnetic induction probe, which differs from Example 1 in that a second plane perpendicular to the axial direction is defined, and the connecting lines formed by connecting the intersection points of the second plane with the axes of the two excitation coils 2 and the two receiving coils 4 in sequence are rhombuses, and the two receiving coils 4 are located on the long diagonal line of the rhombus.

[0058] Example 2 can be regarded as an adjustment of Example 1. The two excitation coils 2 are positioned closer together, which can provide higher sensitivity for longitudinal defect detection when the excitation signal strength is low. The two receiving coils 4 are positioned farther apart. In addition to reducing the interference of the excitation coil 2 on the receiving coil 4, it can also increase the detection range of the probe, which helps the probe detect longitudinal defects.

[0059] Example 3

[0060] Example 3 provides a defect detection device, which includes an alternating power supply and a signal processor, and the omnidirectional defect detection electromagnetic induction probe described in Example 1 or Example 2, wherein the probe is connected to the alternating power supply and sends an induction signal to the signal processor.

[0061] The defect detection device adopts the above-mentioned probe and has omnidirectional defect detection capability, especially having better detection sensitivity for longitudinal defects on the surface of the material being tested.

[0062] The above description and embodiments are used to explain the scope of protection of the utility model, but do not constitute a limitation on the scope of protection of the utility model. Based on the enlightenment of the utility model or the above embodiments, modifications, equivalent replacements, or other improvements to the embodiments of the utility model or part of the technical features thereof that can be obtained by ordinary technicians in this field through logical analysis, reasoning, or limited experiments in combination with common knowledge, ordinary technical knowledge in this field and / or existing technology should be included in the scope of protection of the utility model.

Claims

1. An omnidirectional defect detection electromagnetic induction probe, characterized by comprising: Two excitation components (1), each of the excitation components (1) includes a spirally wound excitation coil (2); the two excitation coils (2) are connected in series and are suitable for generating the same primary electromagnetic field with opposite directions; Two receiving components (3), each receiving component (3) comprising a spirally wound receiving coil (4); the two receiving coils (4) are wound in opposite directions and are adapted to form an induction signal according to the induced secondary electromagnetic field; The axial directions of the excitation coil (2) and the receiving coil (4) are parallel; a first direction and a second direction perpendicular to the axial direction are defined, and a first plane (5) perpendicular to the first direction is defined; The two excitation components (1) are arranged side by side close to each other along a first direction, and the first plane (5) is located between the two excitation components (1) and has the same distance from the axes of the two excitation coils (2); The two receiving components (3) are arranged side by side close to each other along the second direction, and the axes of the two receiving coils (4) are located in the first plane (5).

2. The omnidirectional defect detection electromagnetic induction probe according to claim 1, characterized in that: A second plane perpendicular to the axial direction, wherein the connecting lines formed by sequentially connecting the intersection points of the second plane with the axes of the two excitation coils (2) and the two receiving coils (4) are rhombus-shaped, and the two receiving coils (4) are located on the long diagonal line of the rhombus.

3. The omnidirectional defect detection electromagnetic induction probe according to claim 1, characterized in that: A second plane perpendicular to the axis direction, wherein the connecting lines formed by sequentially connecting the intersection points of the second plane with the axes of the two excitation coils (2) and the two receiving coils (4) are squares.

4. An omnidirectional defect detection electromagnetic induction probe according to claim 2 or 3, characterized in that: The excitation coil (2) and the receiving coil (4) are wound with copper wires of the same properties.

5. The omnidirectional defect detection electromagnetic induction probe according to claim 4, characterized in that: The diameters of the two receiving coils (4) are equal, and the diameters of the excitation coil (2) and the receiving coil (4) are equal.

6. The omnidirectional defect detection electromagnetic induction probe according to claim 5, characterized in that: The excitation component (1) further includes a cylindrical excitation magnetic core (6), and the receiving component (3) further includes a cylindrical receiving magnetic core (7); the excitation coil (2) is wound around the circumferential surface of the excitation magnetic core (6), and on the detection end side of the excitation component (1), the end of the excitation magnetic core (6) is exposed by a preset length of the excitation coil (2); the receiving coil (4) is wound around the circumferential surface of the receiving magnetic core (7), and on the induction end side of the receiving component (3), the end of the receiving magnetic core (7) is exposed by a preset length of the receiving coil (4).

7. The omnidirectional defect detection electromagnetic induction probe according to claim 6, characterized in that: The exciting magnetic core (6) and the receiving magnetic core (7) are both ferrite cores.

8. The omnidirectional defect detection electromagnetic induction probe according to claim 6, characterized in that: The invention also includes a shell (8), which is cylindrical and surrounds the two excitation components (1) and the two receiving components (3), and has detection marks (9) provided on its outer surface at positions corresponding to the two excitation components (1); the shell (8) is provided with an opening for exposing the detection end of the excitation component (1) and the receiving end of the receiving component (3).

9. The omnidirectional defect detection electromagnetic induction probe according to claim 8, characterized in that: The shell (8) is made of aluminum alloy.

10. A defect detection device comprising an alternating power supply and a signal processor, characterized in that: It also includes an omnidirectional defect detection electromagnetic induction probe according to any one of claims 1 to 9, wherein the probe is connected to the alternating power supply and sends an induction signal to the signal processor.

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