A highly flexible ultrasonic probe tracking and connecting device and a non-destructive testing method in a pipeline

Abstract

The present invention relates to the field of non-destructive testing, and specifically to a highly flexible ultrasonic probe tracking connection device and a non-destructive testing method inside a pipeline. It includes tracking probes uniformly arranged circumferentially along the detection cabin. Each tracking probe is hinged with the detection cabin, and the hinge axis is perpendicular to the axis of the detection cabin. The tracking probe includes a tracking block moving along the pipeline and an electromagnetic ultrasonic probe. Along the advancing direction of the detection cabin, at least one set of springs is provided in front of and behind the ultrasonic probe, and the ultrasonic probe is elastically floatingly arranged on the tracking block through the springs. Along the advancing direction of the detection cabin, at least one set of guiding mechanisms moving along the pipe wall and / or the weld is provided in front of and behind the ultrasonic probe. Along the radial direction of the detection cabin, there is a working gap between the guiding surface of the guiding mechanism and the detection surface of the ultrasonic probe. The present invention optimizes the running posture of the electromagnetic ultrasonic probe, making it always parallel to the pipe wall of the pipeline or the weld of the bent protrusion, and greatly reducing the detection error.

Description

Technical Field

[0001] The present invention relates to the field of non-destructive testing, and specifically to a highly flexible ultrasonic probe tracking connection device and a non-destructive testing method inside a pipeline. Background Art

[0002] Industrial pipelines are prone to problems such as corrosion, cracking, and leakage under complex operating conditions. During daily operations, it is necessary to regularly inspect the pipelines to promptly detect and handle various potential hazards to ensure that they are always in the best operating state. Currently, common non-destructive testing methods for pipelines include magnetic flux leakage testing, eddy current testing, magnetic particle testing, ultrasonic testing, electromagnetic ultrasonic testing, etc. Among them, electromagnetic ultrasonic testing mainly excites and receives ultrasonic echoes through an electromagnetic field, does not require a coupling agent, is resistant to high temperatures, can have a certain lift-off height, and can detect pipeline defects and thicknesses in a high-temperature environment.

[0003] Although electromagnetic ultrasonic probes have the advantage of being non-contact, the lift-off distance reduces the conversion efficiency of ultrasonic energy and electromagnetic energy. As described in the traditional electromagnetic ultrasonic probe with the publication number "CN118425294A", the circumferential detection of the pipeline to be measured can be carried out by the circumferential sliding of the electromagnetic ultrasonic probe on the sliding guide rail. When the pipeline robot pulls the electromagnetic ultrasonic probe to travel along the pipeline, during the process of passing through the pipeline elbow and the weld, the operating posture of the electromagnetic ultrasonic probe will be affected by the protrusion of the weld and the bend of the pipeline elbow. The ultrasonic probe cannot always be parallel to the pipe wall of the pipeline or the bent and protruding weld, resulting in a large detection error of the probe. Therefore, it is urgent to solve. Summary of the Invention

[0004] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a highly flexible ultrasonic probe tracking connection device and a non-destructive testing method inside a pipeline. The present invention optimizes the operating posture of the electromagnetic ultrasonic probe to keep it always parallel to the pipe wall of the pipeline or the bent and protruding weld, greatly reducing the detection error.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A highly flexible ultrasonic probe tracking connection device includes tracking probes uniformly arranged circumferentially along the detection cabin. Each tracking probe is hinged with the detection cabin, and the hinge axis is perpendicular to the axis of the detection cabin; the tracking probe includes a tracking block traveling along the pipeline and an electromagnetic ultrasonic probe; along the traveling direction of the detection cabin, at least one set of springs is arranged in front of and behind the ultrasonic probe, and the ultrasonic probe is elastically floatingly arranged on the tracking block through the springs; along the traveling direction of the detection cabin, at least one set of guiding mechanisms traveling along the pipe wall and / or the weld is arranged in front of and behind the ultrasonic probe. Along the radial direction of the detection cabin, there is a working gap between the guiding surface of the guiding mechanism and the detection surface of the ultrasonic probe.

[0007] As a further solution of the present invention: the guiding mechanism is an inner floating roller installed at the end of the ultrasonic probe, and the ultrasonic probe rolls along the pipe wall and / or the weld through the inner floating roller; outer floating rollers are further arranged at the front and rear ends of the tracking block, and the rolling axis of the outer floating roller is parallel to the axis of the inner floating roller.

[0008] As a further solution of the present invention: along the traveling direction of the detection cabin, there are two groups of inner floating rollers, which are symmetrically arranged on both sides of the ultrasonic probe.

[0009] As a further solution of the present invention: the tracking probe is hinged to the cabin body of the detection cabin through a connecting rod, and the hinge axis is parallel to the axis of the inner floating roller. A torsion spring for applying an elastic thrust towards the pipe wall direction to the connecting rod is further arranged on the detection cabin.

[0010] As a further solution of the present invention: an installation cavity for installing the ultrasonic probe is provided at the center of the tracking block, and springs are arranged at the four corner ends of the installation cavity, so as to be fixedly connected to the four corner ends of the ultrasonic probe.

[0011] As a further solution of the present invention: the detection cabin is coaxially fixed to the signal cabin through a connecting rod, a universal joint is arranged at the axis center of the detection cabin and / or the signal cabin, and the universal joint housing is made of polyurethane material; first centering wheels are uniformly arranged along the circumferential direction on the outer circle of the detection cabin, and second centering wheels are uniformly arranged along the circumferential direction on the outer circle of the signal cabin.

[0012] A non-destructive testing method includes the following steps:

[0013] S1. Install the described high-flexibility ultrasonic probe tracking connection device in the pipeline;

[0014] S2. Measure the supporting force received by the ultrasonic probe along the radial direction through a sensor F , and adjust the model of the spring and / or the excitation voltage of the coil in the ultrasonic probe U , so that the detection surface of the ultrasonic probe keeps in close contact with the pipe wall and / or the weld;

[0015] ;

[0016] Among them, k represents the elastic coefficient of the spring;

[0017] l represents the length of the spring in the working state;

[0018] l 0 represents the original length of the spring;

[0019] represents the included angle between the spring and the axis of the ultrasonic probe in the working state;

[0020] U represents the excitation voltage of the coil in the ultrasonic probe;

[0021] d 1 represents the wire diameter of the coil in the ultrasonic probe;

[0022] ρ represents the resistivity of the coil wire in the ultrasonic probe;

[0023] D represents the average diameter of the coil in the ultrasonic probe;

[0024] represents the differential of the air gap of the electromagnet in the ultrasonic probe with respect to the air gap length;

[0025] represents the magnetic attraction of the permanent magnet on the ultrasonic probe;

[0026] S3. Traction detection cabin and signal cabin by the pipeline robot to travel in the pipeline, so that each tracking probe passes through the weld to detect the weld.

[0027] As a further solution of the present invention: In step S2, the length of the spring in the working state l shall meet the following conditions:

[0028] ;

[0029] wherein, a represents the length of the tracking block;

[0030] b represents the width of the tracking block;

[0031] c represents the length of the ultrasonic probe;

[0032] d represents the width of the ultrasonic probe;

[0033] h 1 represents the height difference between the detection surface of the ultrasonic probe and the tracking block;

[0034] h 0 represents the distance between the connection point of the spring and the ultrasonic probe and the detection surface of the ultrasonic probe.

[0035] As a further solution of the present invention: Before the device runs, measure under the state that the ultrasonic probe is not powered on .

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] 1. The electromagnetic ultrasonic probe of the present invention is elastically and floatingly arranged on the tracking block. When the tracking block travels along the pipeline and passes through elbows or welds, the ultrasonic probe elastically floats under the action of a spring and travels along the elbow or weld through the inner floating rollers at both ends thereof, which can ensure that the detection surface of the ultrasonic probe always maintains a parallel and close contact state with the elbow or weld, giving the ultrasonic probe degrees of freedom in multiple directions, optimizing the operating posture of the electromagnetic ultrasonic probe, making it always parallel to the pipe wall or the weld of the bent protrusion, and greatly reducing the detection error.

[0038] 2. Based on more degrees of freedom of the probe, the tracking device of the present invention combines the adsorption force between the permanent magnet in the electromagnetic ultrasonic probe and the ferromagnetic pipeline. The electromagnetic ultrasonic probe carried by the detection cabin can change its own angle in the elbow, so as to ensure close contact with both sides of the pipeline; since the present invention uses a universal joint with a polyurethane shell, which has a certain elasticity, it can effectively limit the excessive torsion and deformation of the universal joint in the pipeline and stabilize the operating postures of the detection cabin and the signal cabin.

[0039] 3. The present invention establishes a calculation formula for the supporting force received by the ultrasonic probe. By adjusting the spring model to change its telescopic length or elastic coefficient, or adjusting the excitation voltage of the coil in the ultrasonic probe, the supporting force received by the ultrasonic probe is changed. Through calculation, the optimal supporting force in its equilibrium state can be obtained, avoiding excessive supporting force from increasing the traveling resistance of the device and also avoiding too small supporting force from causing the inner floating rollers on both sides of the ultrasonic probe to disengage from the pipe wall or weld. Description of the Drawings

[0040] Figure 1 It is a schematic structural diagram of the present invention.

[0041] Figure 2 It is a schematic structural diagram of the tracking probe in the present invention.

[0042] Figure 3 It is a top view of the tracking probe in the present invention.

[0043] Figure 4a It is a schematic diagram of the state when the ultrasonic probe in the present invention does not pass through the weld.

[0044] Figure 4b It is a schematic diagram of the state when the ultrasonic probe in the present invention passes through the starting end of the weld.

[0045] Figure 4c It is a schematic diagram of the state when the ultrasonic probe in the present invention passes through the middle section of the weld.

[0046] Figure 4d It is a schematic diagram of the state when the ultrasonic probe in the present invention passes through the end of the weld.

[0047] Figure 5a Schematic diagram of the state of an existing ultrasonic probe when it does not pass through the weld seam.

[0048] Figure 5b Schematic diagram of the state of an existing ultrasonic probe when it passes through the starting end of the weld seam.

[0049] Figure 5c Schematic diagram of the state of an existing ultrasonic probe when it passes through the middle section of the weld seam.

[0050] Figure 5d Schematic diagram of the state of an existing ultrasonic probe when it passes through the end of the weld seam.

[0051] Figure 6 Schematic diagram of the state of the ultrasonic probe in the present invention when it passes through the pipe elbow.

[0052] Figure 7 Schematic diagram of the state of an existing ultrasonic probe when it passes through the pipe elbow.

[0053] In the figure:

[0054] 1. Detection cabin; 11. Tracking probe;

[0055] 111. Tracking block; 112. Ultrasonic probe; 113. Inner floating roller;

[0056] 114. Outer floating roller; 115. Spring;

[0057] 12. Connecting rod; 13. First centering wheel;

[0058] 2. Signal cabin; 21. Second centering wheel;

[0059] 3. Connecting rod; 4. Universal joint. Detailed implementation manner

[0060] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0061] Please refer to Figures 1-7, in an embodiment of the present invention, a highly flexible ultrasonic probe tracking and connecting device includes a detection cabin 1 and a signal cabin 2. The detection cabin 1 and the signal cabin 2 are coaxially connected and fixed through a connecting rod 3. Universal joints 4 are provided at the ends of the detection cabin 1 and the signal cabin 2, and can be connected to the connecting rod 3 through the universal joints 4, or connected to a pipeline robot through the universal joints 4, and travel along the pipeline under the traction of the pipeline robot. The distance between the detection cabin 1 and the signal cabin 2 can be changed by replacing the connecting rod 3 with different lengths to meet the requirements of different pipeline detections. The housing of the universal joint 4 can be set as a polyurethane housing, and the elastic connection between the detection cabin 1 and the signal cabin 2 can be adaptively changed by replacing polyurethane housings with different specifications.

[0062] First centering wheels 13 and second centering wheels 21 are respectively arranged circumferentially on the outer circles of the detection cabin 1 and the signal cabin 2, which are used to maintain the stability and directionality of the robot in the pipeline, ensuring that the robot can smoothly pass through the pipeline and carry out effective detection and maintenance work.

[0063] Link rods 12 are evenly arranged circumferentially on the detection cabin 1. The link rods 12 are hinged with the detection cabin 1, and the hinge axis is perpendicular to the axis of the detection cabin 1. A tracking probe 11 is installed at the end of the link rod 12. During the rotation of the link rod 12, the tracking probe 11 is driven to move towards the inner pipe wall of the pipeline, so that the tracking probe 11 is close to the pipe wall. A torsion spring can be arranged between the link rod 12 and the detection cabin 1, and an elastic force is applied to the link rod 12 through the torsion spring, so that the tracking probe 11 always abuts against the pipe wall.

[0064] The tracking probe 11 includes a tracking block 111. A cavity is provided at the center of the tracking block 111 for installing an electromagnetic ultrasonic probe 112. The cavity of the tracking block 111 is a rectangular cavity, and four groups of springs 115 are respectively arranged at the four corner ends of the cavity, so as to be connected and fixed with the four corner ends of the ultrasonic probe 112, forming an elastic floating connection between the ultrasonic probe 112 and the tracking block 111.

[0065] Along the traveling direction of the detection cabin 1, outer floating rollers 114 that can travel along the pipe wall are arranged at both the front and rear ends of the tracking block 111. The two outer floating rollers 114 are symmetrically arranged on both sides of the ultrasonic probe 112. Inner floating rollers 113 are also installed at the front and rear ends of the ultrasonic probe 112 through brackets. The inner floating rollers 113 are connected to the ultrasonic probe 112 through pins. The axes of the inner floating rollers 113 and the outer floating rollers 114 are arranged in parallel and are parallel to the tangent of the outer wall. The inner floating rollers 114 are preferably of a bearing structure.

[0066] While the tracking block 111 travels along the pipeline through the outer floating roller 114, the outer ring of the inner floating roller 113 rolls along the pipe wall or weld of the pipeline. When the inner floating roller 113 fits the pipe wall or weld, there is still a certain distance between the detection surface of the ultrasonic probe 112 and the pipe wall or weld. By changing the radius of the inner floating roller 113, the lift-off height between the electromagnetic ultrasonic probe 112 and the pipe wall can be changed.

[0067] Let the lift-off height of the ultrasonic probe 112 be T , the height difference between the pipe contact surface of the inner floating roller 113 and the detection surface of the ultrasonic probe 112 be H , the radius of the pipeline to be detected be R , and the width of the inner floating roller 113 be d 0 , then T satisfies:

[0068] .

[0069] The detection of the present invention includes the following steps:

[0070] S1. Install a highly flexible ultrasonic probe tracking and connecting device in the pipeline;

[0071] S2. Measure the supporting force received by the ultrasonic probe 112 in the radial direction through the sensor F , and adjust the model of the spring 115 and / or the excitation voltage of the coil in the ultrasonic probe 112 U to keep the detection surface of the ultrasonic probe 112 in close contact with the pipe wall and / or weld;

[0072] ;

[0073] Among them, k represents the elastic coefficient of the spring 115;

[0074] l represents the length of the spring 115 in the working state;

[0075] l 0 represents the original length of the spring 115;

[0076] represents the angle between the spring 115 and the axis of the ultrasonic probe 112 in the working state;

[0077] U represents the excitation voltage of the coil in the ultrasonic probe 112;

[0078] d 1 represents the wire diameter of the coil in the ultrasonic probe 112;

[0079] ρ represents the resistivity of the coil wire in the ultrasonic probe 112;

[0080] D represents the average diameter of the coil in the ultrasonic probe 112;

[0081] represents the differential of the air gap of the electromagnet in the ultrasonic probe 112 with respect to the air gap length;

[0082] represents the magnetic attraction force of the permanent magnet on the ultrasonic probe 112;

[0083] Among them, the elastic force exerted by the four springs 115 on the ultrasonic probe 112 needs to satisfy ;

[0084] Among them F 0 represents the elastic force exerted by a single spring 115 on the ultrasonic probe 112;

[0085] G represents the gravity of the ultrasonic probe 112 itself.

[0086] Due to , ;

[0087] Then the length of the spring 115 in the working state l needs to satisfy the following conditions:

[0088] ;

[0089] Among them, a represents the length of the tracking block 111;

[0090] b represents the width of the tracking block 111;

[0091] c represents the length of the ultrasonic probe 112;

[0092] d represents the width of the ultrasonic probe 112;

[0093] h 1 represents the height difference between the detection surface of the ultrasonic probe 112 and the tracking block 111;

[0094] h 0 represents the distance between the connection point of the spring 115 and the ultrasonic probe 112 to the detection surface of the ultrasonic probe 112.

[0095] The supporting force received by the ultrasonic probe 112F Apply an elastic force to the spring 115 And the magnetic suction force of the ultrasonic probe The sum, that is . And Is the magnetic suction force of the permanent magnet And the electromagnetic suction force generated when the coil in the ultrasonic probe 112 is energized The sum, that is .

[0096] ;

[0097] In the formula, IN Is the magnetic potential generated when the coil is energized, where I Is the current passing through the coil, N Is the number of turns of the coil, Represents the differential of the air gap length of the electromagnet in the ultrasonic probe 112 with respect to the air gap length. When the mechanical dimensions of the electromagnet are determined, Can be considered as a definite value.

[0098] Assume that the average diameter of the coil in the ultrasonic probe 112 is D , the wire diameter of the coil is d 1 , the average supply voltage is U , the resistivity of the coil wire is ρ , then the resistance of the coil R Can be expressed as:

[0099] ;

[0100] In the formula: Is the cross-sectional area of the wire; Is the average turn length of the coil.

[0101] Combining the above formula with Ohm's law We can get , so Can be expressed as:

[0102] .

[0103] S3. Use the pipeline robot to tow the detection cabin 1 and the signal cabin 2 to move in the pipeline, so that each tracking probe 11 passes through the weld and detects the weld.

[0104] Before the device runs, when the ultrasonic probe 112 is not energized, The size can be measured.

[0105] As Figures 5a-5d Shown, when the traditional ultrasonic probe passes through the uneven weld in the pipeline, the ultrasonic probe can only move along the direction parallel to the pipe wall and cannot always closely adhere to the bent weld.

[0106] In the present invention, as Figures 4a-4d shown, when passing through the concave-convex weld seam, due to the elastic floating setting of the ultrasonic probe 112, under the action of the magnetic suction force, the ultrasonic probe 112 can always closely adhere to the weld seam during travel, and the distance from the weld seam remains constant, greatly improving the detection accuracy.

[0107] As Figures 6-7 shown, different from the fact that the existing ultrasonic probe cannot adaptively rotate and change direction when passing through a pipe elbow, when the ultrasonic probe of the present invention passes through a pipe elbow, each probe on the outer ring of the detection cabin 1 can change its own angle through elastic floating and always adaptively adhere to the pipe wall of the elbow section.

[0108] The basic principles of the present application have been described in combination with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present application. In addition, the above-disclosed specific details are only for the purposes of illustration and easy understanding, rather than limitations. The above details do not limit the present application to necessarily adopt the above specific details for implementation.

[0109] The block diagrams of the devices, apparatuses, equipment, and systems involved in the present application are only illustrative examples and do not intend to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open-ended words, meaning "including but not limited to", and can be used interchangeably with each other. The word "or" and "and" used here refer to the word "and / or", and can be used interchangeably with each other, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to", and can be used interchangeably with each other.

Claims

1. A highly flexible ultrasonic probe tracking connection device, characterized in that: The invention comprises tracking probes (11) uniformly arranged along the circumference of the detection chamber (1), each tracking probe (11) being hingedly matched with the detection chamber (1), and the hinge axis being perpendicular to the axis of the detection chamber (1); the tracking probe (11) comprising a tracking block (111) moving along the pipeline and an electromagnetic ultrasonic probe (112); at least one set of springs (115) is arranged in front of and behind the ultrasonic probe (112) along the moving direction of the detection chamber (1), and the ultrasonic probe (112) is elastically floated on the tracking block (111) by means of the springs (115); at least one set of guiding mechanisms moving along the pipe wall and / or the weld is arranged in front of and behind the ultrasonic probe (112) along the moving direction of the detection chamber (1), and a working gap exists between the guiding surface of the guiding mechanism and the detection surface of the ultrasonic probe (112) along the radial direction of the detection chamber (1); A mounting cavity for mounting an ultrasonic probe (112) is provided at the center of the tracking block (111), and springs (115) are provided at the four corner ends of the mounting cavity so as to be connected and fixed to the four corner ends of the ultrasonic probe (112).

2. A highly flexible ultrasonic probe tracking connection device according to claim 1, characterized in that: The guide mechanism is an inner floating roller (113) installed at the end of the ultrasonic probe (112), and the ultrasonic probe (112) rolls along the pipe wall and / or the weld via the inner floating roller (113); outer floating rollers (114) are also provided at the front and rear ends of the tracking block (111), and the rolling axis of the outer floating roller (114) is parallel to the axis of the inner floating roller (113).

3. A highly flexible ultrasonic probe tracking connection device according to claim 2, characterized in that: Along the moving direction of the detection cabin (1), two groups of inner floating rollers (113) are provided and are symmetrically arranged on both sides of the ultrasonic probe (112).

4. A highly flexible ultrasonic probe tracking connection device according to claim 2 or 3, characterized in that: The tracking probe (11) is hingedly matched with the body of the detection chamber (1) via a connecting rod (12), the hinge axis is parallel to the axis of the inner floating roller (113), and the detection chamber (1) is also provided with a torsion spring for applying an elastic thrust to the connecting rod (12) in the direction of the pipe wall.

5. A highly flexible ultrasonic probe tracking connection device according to any one of claims 1 to 3, characterized in that: The detection cabin (1) is coaxially fixed with the signal cabin (2) via a connecting rod (3); a universal joint (4) is arranged at the axis of the detection cabin (1) and / or the signal cabin (2); the outer shell of the universal joint (4) is made of polyurethane material; first righting wheels (13) are evenly arranged along the circumference of the outer ring of the detection cabin (1); and second righting wheels (21) are evenly arranged along the circumference of the outer ring of the signal cabin (2).

6. A non-destructive testing method, characterized in that: The steps include: S1. Installing a highly flexible ultrasonic probe tracking connection device as described in any one of claims 1 to 3 in a pipeline; S2. Measuring the radial support force of the ultrasonic probe (112) by a sensor F , adjust the type of spring (115) and / or the excitation voltage of the coil in the ultrasonic probe (112) U , so that the detection surface of the ultrasonic probe (112) is kept in close contact with the pipe wall and / or the weld; ； in, k represents the elastic constant of the spring (115); l represents the length of the spring (115) in the working state; l 0 represents the original length of the spring (115); represents the angle between the spring (115) and the axis of the ultrasonic probe (112) in the working state; U represents the excitation voltage of the coil in the ultrasonic probe (112); d 1 represents the wire diameter of the coil in the ultrasonic probe (112); ρ represents the resistivity of the coil wire in the ultrasonic probe (112); D represents the average diameter of the coil in the ultrasonic probe (112); represents the differential of the air gap length of the electromagnet in the ultrasonic probe (112); F 永磁 represents the magnetic attraction force of the permanent magnet exerted on the ultrasonic probe (112); S3, using the pipeline robot to pull the detection cabin (1) and the signal cabin (2) to move in the pipeline, so that each tracking probe (11) passes through the weld and detects the weld.

7. A nondestructive testing method according to claim 6, characterized in that: In step S2, the length of the spring (115) in the working state is l The following conditions must be met: ； in, a Indicates the length of the tracking block (111); b Indicates the width of the tracking block (111); c represents the length of the ultrasonic probe (112); d represents the width of the ultrasonic probe (112); h 1 Indicates the height difference between the detection surface of the ultrasonic probe (112) and the tracking block (111); h 0 Indicates the distance between the connection point between the spring (115) and the ultrasonic probe (112) and the detection surface of the ultrasonic probe (112).

8. A nondestructive testing method according to claim 6, characterized in that: Before the device is operated, the ultrasonic probe (112) is not powered on and the measurement is performed. F 永磁 .

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