A magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field adjustment

Abstract

The present invention relates to the technical field of ultrasonic guided wave nondestructive testing, and in particular to a magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field adjustment, comprising a first circumferential static magnetic field array unit, a second circumferential static magnetic field array unit and an alternating magnetic field generating unit; the first circumferential static magnetic field array unit is formed on the periphery of one end of the part to be detected, and is capable of generating a static magnetic field in the circumferential direction of the part to be detected. The second circumferential static magnetic field array unit is also formed on the periphery of one end of the part to be detected, and is arranged opposite to the first circumferential static magnetic field array unit, and is capable of generating a static magnetic field in the circumferential direction of the part to be detected. The second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit can move toward each other. The second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit can rotate relative to each other. This not only ensures the stability of the bias magnetic field, but also enables the precise adjustment of the size of the static bias magnetic field.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic guided wave nondestructive testing, and in particular to a magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation. Background Art

[0002] The grounding rods of transmission towers are made of steel with a circular cross-section. Because they remain buried beneath the surface for extended periods, corrosion and fracture are inevitable, threatening the safe operation of the power system and even the safety of workers. Therefore, regular inspection of grounding rods is essential. Conventional nondestructive testing methods, such as magnetic particle testing, X-ray testing, and eddy current testing, are not suitable for these complex working conditions. Magnetostrictive guided wave testing, however, can detect areas inaccessible to conventional testing and is therefore widely used for trenchless nondestructive testing of grounding rods.

[0003] The principle of magnetostrictive guided wave testing is to generate a magnetic field at one axial end of the grounding rod. This magnetic field, also known as the bias field, is used to excite longitudinal guided waves within the grounding rod and is a key element in defect detection. A bias field can be provided using a powered coil. While the magnitude of the field can be precisely adjusted to suit the specific application scenario, the resulting bias field is unstable and can cause electromagnetic interference to the guided wave receiving signal. Alternatively, a bias field can be provided using permanent magnets. While this field is sufficiently stable, the magnitude can only be adjusted in small increments by increasing or decreasing the number of permanent magnets, and precise adjustment is not possible.

[0004] Therefore, how to ensure the stability of the bias magnetic field and accurately adjust the magnitude of the bias magnetic field has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] The present invention provides a magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation, so as to solve the problem of how to ensure the stability of the bias magnetic field and accurately adjust the magnitude of the bias magnetic field.

[0006] In one aspect, the present invention provides a magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation, comprising:

[0007] A first circumferential static magnetic field array unit is formed on the periphery of the object to be detected;

[0008] a second circumferential static magnetic field array unit, formed on the periphery of the to-be-detected component and arranged opposite to the first circumferential static magnetic field array unit; the second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit are movable toward each other; and the second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit are relatively rotatable;

[0009] The alternating magnetic field generating unit is arranged between the second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit, and is wound around the periphery of the part to be detected.

[0010] In some embodiments, the second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit are capable of moving toward each other by 0-40 mm.

[0011] In some embodiments, the second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit can rotate relative to each other by 0-20°.

[0012] In some embodiments, the first circumferential static magnetic field array unit includes:

[0013] There are a plurality of first static magnetic field generating elements, which are evenly distributed along the circumference of the first circumferential static magnetic field array unit;

[0014] a plurality of second static magnetic field generating members, arranged alternately with the first static magnetic field generating members along the circumferential direction of the first circumferential static magnetic field array unit;

[0015] The second circumferential static magnetic field array unit includes:

[0016] a plurality of third static magnetic field generating members uniformly distributed along the circumference of the second circumferential static magnetic field array unit;

[0017] a plurality of fourth static magnetic field generating elements, arranged alternately with the third static magnetic field generating elements along the circumferential direction of the second circumferential static magnetic field array unit;

[0018] A portion of the top of each third static magnetic field generating element covers a portion of the top of a first static magnetic field generating element; a portion of the top of each second static magnetic field generating element covers a portion of the top of a fourth static magnetic field generating element.

[0019] In some embodiments, each first static magnetic field generating element comprises:

[0020] a first permanent magnet;

[0021] The first converging armature piece is fixedly mounted on the bottom of the first permanent magnet and can be attached to the outer wall of the part to be detected;

[0022] A first transfer armature piece is fixedly mounted on the top of the first permanent magnet;

[0023] A first steering armature piece, one end of which is fixedly mounted on the top of the first transfer armature piece, and the other end of which extends toward the third static magnetic field generating element, and a top surface of which is provided with an upper thread;

[0024] Each third static magnetic field generating element comprises:

[0025] a second permanent magnet;

[0026] The second converging armature piece is fixedly mounted on the bottom of the second permanent magnet and can be attached to the outer wall of the part to be detected;

[0027] A second transfer armature piece is fixedly mounted on the top of the second permanent magnet;

[0028] The armature piece is raised and fixedly installed on the top of the second transfer armature piece;

[0029] A second steering armature piece has one end fixedly mounted on the top of the raised armature piece and the other end extending toward the first static magnetic field generating member, and a bottom surface provided with a lower thread; a portion of the second steering armature piece is connected to a portion of the first steering armature piece via the lower thread and the upper thread;

[0030] The structure of each second static magnetic field generating member is the same as that of each third static magnetic field generating member; the structure of each fourth static magnetic field generating member is the same as that of each first static magnetic field generating member; a portion of the second steering armature piece of each second static magnetic field generating member is connected to a portion of the first steering armature piece of each fourth static magnetic field generating member through a lower thread and an upper thread.

[0031] In some embodiments, the first circumferential static magnetic field array unit further comprises:

[0032] A first supporting ring has an inner wall formed with a first mounting groove for mounting the first static magnetic field generating element and a second mounting groove for mounting the second static magnetic field generating element;

[0033] The second circumferential static magnetic field array unit includes:

[0034] The second supporting ring has an inner wall formed with a third mounting groove for mounting the third static magnetic field generating element and a fourth mounting groove for mounting the fourth static magnetic field generating element.

[0035] In some embodiments, a plurality of first support segments are sequentially connected to form a first support ring;

[0036] A plurality of second support segments are connected in sequence to form a second support ring.

[0037] The beneficial effects of the present invention are as follows: The magnetostrictive longitudinal wave transducer structure capable of static magnetic field adjustment of the present invention comprises a first circumferential static magnetic field array unit, a second circumferential static magnetic field array unit, and an alternating magnetic field generating unit. The first circumferential static magnetic field array unit is formed on the periphery of one end of the object to be detected and is capable of generating a static magnetic field circumferentially of the object to be detected. The second circumferential static magnetic field array unit is also formed on the periphery of one end of the object to be detected and is disposed opposite the first circumferential static magnetic field array unit. The second circumferential static magnetic field array unit is also capable of generating a static magnetic field circumferentially of the object to be detected. The second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit are capable of moving toward each other to precisely adjust the magnitude of the static bias magnetic field. The second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit are capable of rotating relative to each other to precisely adjust the magnitude of the static bias magnetic field. This ensures the stability of the bias magnetic field while enabling precise adjustment of the magnitude of the bias magnetic field. The alternating magnetic field generating unit is disposed between the second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit, wound around the periphery of one end of the object to be detected, and is capable of generating an alternating bias magnetic field. By coupling a static bias magnetic field with an alternating bias magnetic field, the grounding rod is excited to generate longitudinal modal guided waves along its axial direction. Defects on the grounding rod are detected by receiving these longitudinal modal guided waves. By varying the strength of the static bias magnetic field, the magnetostrictive effect is located in the operating region near the maximum slope change on the magnetization curve, thereby stimulating a guided wave signal with maximum energy and improving the conversion efficiency of the magnetostrictive effect from electrical energy to mechanical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagrams of some specific embodiments of a magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation according to the present invention;

[0039] Figure 2 yes Figure 1 The displacement distribution diagram of the cross section of the object to be detected in the horizontal direction when the magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation is working;

[0040] Figure 3 yes Figure 1 The displacement distribution diagram of the cross section of the object to be detected in the vertical direction when the magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation is working;

[0041] Figure 4 yes Figure 1 The displacement distribution diagram of the cross section of the object to be detected in the axial direction when the magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation is working;

[0042] Figure 5 Schematic diagrams of other specific embodiments of a magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation according to the present invention;

[0043] Figure 6 1 is a schematic structural diagram of some specific embodiments of a magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation according to the present invention;

[0044] Figure 7 yes Figure 1 A schematic diagram of the magnetic flux density in the axial direction of the component to be detected when the first circumferential static magnetic field array unit and the second circumferential static magnetic field array unit of the magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation are moved toward each other;

[0045] Figure 8 yes Figure 5 A schematic diagram of the magnetic flux density in the axial direction of the component to be detected when the first circumferential static magnetic field array unit and the second circumferential static magnetic field array unit of the magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation are moved toward each other;

[0046] Figure 9 yes Figure 5 A schematic diagram of the magnetic flux density in the axial direction of the object to be detected when the first circumferential static magnetic field array unit and the second circumferential static magnetic field array unit of the magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation are relatively rotated;

[0047] Figure 10 yes Figure 5 Polar coordinate diagram of magnetic field distribution at the middle position of the grounding rod segment covered by the magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation;

[0048] Figure 11 It is a structural schematic diagram of some specific embodiments of a defect detection device of the present invention;

[0049] Figure 12 It is the use of Figure 11 Schematic diagram of the echo signal detected by the defect detection device shown.

[0050] In the accompanying drawings, 100, a magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation; 110, a first circumferential static magnetic field array unit; 111, a first static magnetic field generating element; 1111, a first permanent magnet; 1112, a first converging armature piece; 1113, a first transfer armature piece; 1114, a first steering armature piece; 112, a second static magnetic field generating element; 113, a first supporting ring; 1131, a first supporting section; 1132, a first connecting block; 120, a second circumferential static magnetic field array unit; 121, a third static magnetic field generating element; Magnetic field generating element; 1211, second permanent magnet; 1212, second converging armature piece; 1213, second transfer armature piece; 1214, raising armature piece; 1215, second steering armature piece; 122, fourth static magnetic field generating element; 123, second support ring; 1231, second support section; 1232, second connecting block; 130, alternating magnetic field generating unit; 200, part to be detected; 310, signal generating module; 320, power amplifying module; 330, signal amplifying module; 340, signal processing module. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] As described in the background technology, a bias magnetic field can be provided by using a powered coil. Although the magnitude of the magnetic field can be precisely adjusted according to the actual use scenario, the resulting bias magnetic field is not stable enough and can cause electromagnetic interference to the waveguide receiving signal. A bias magnetic field can also be provided by using a permanent magnet. Although the magnetic field is sufficiently stable, the magnitude of the magnetic field can only be significantly adjusted by increasing or decreasing the number of permanent magnets, and the magnitude of the magnetic field cannot be precisely adjusted. Therefore, how to ensure the stability of the bias magnetic field while precisely adjusting the magnitude of the bias magnetic field has become a technical problem that needs to be solved urgently by those skilled in the art.

[0053] To solve the above problems, refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 、 Figure 9 、 Figure 10 and Figure 11On the one hand, the present invention provides a magnetostrictive longitudinal wave transducer structure 100 capable of adjusting a static magnetic field, comprising a first circumferential static magnetic field array unit 110, a second circumferential static magnetic field array unit 120, and an alternating magnetic field generating unit 130. The first circumferential static magnetic field array unit 110 is formed on the periphery of one end of a part to be detected 200 and is capable of generating a static magnetic field in the circumferential direction of the part to be detected 200. The second circumferential static magnetic field array unit 120 is also formed on the periphery of one end of the part to be detected 200 and is disposed opposite the first circumferential static magnetic field array unit 110. The second circumferential static magnetic field array unit 120 is also capable of generating a static magnetic field in the circumferential direction of the part to be detected 200. The second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 are capable of moving toward each other to precisely adjust the magnitude of the static bias magnetic field. The second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 are capable of rotating relative to each other to precisely adjust the magnitude of the static bias magnetic field. This ensures the stability of the bias magnetic field while enabling precise adjustment of the magnitude of the bias magnetic field. The alternating magnetic field generating unit 130 is arranged between the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110, and is wound around the outer periphery of one end of the part to be detected 200, and can generate an alternating bias magnetic field. It should be noted that the part to be detected 200 is a grounding rod or other rod-shaped part that is not easily accessible. By coupling the static bias magnetic field with the alternating bias magnetic field, the grounding rod is stimulated to generate longitudinal modal waveguides along the axial direction, and then the longitudinal modal waveguides are received to detect defects on the grounding rod. By changing the intensity of the static bias magnetic field, the magnetostrictive effect is located in the working area near the maximum value of the slope change on the magnetization curve, thereby exciting a waveguide signal with maximum energy, thereby improving the conversion efficiency of the magnetostrictive effect electrical energy and mechanical energy.

[0054] Preferably, the alternating magnetic field generating unit 130 is a coil with a certain number of turns.

[0055] Preferably, the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 are capable of moving toward each other by 0-40 mm. Without changing the specifications of the permanent magnets used in the circumferential static magnetic field array unit, by changing the length of the magnetic circuit, the uniformity of the magnetic field distribution within the grounding rod can be improved, and the strength of the static bias magnetic field can be increased. Since the alternating magnetic field generating unit 130 is theoretically selected based on the wavelength, the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 that are capable of moving toward each other can match the coil specifications at different frequencies without the need to redesign the magnetic circuit.

[0056] Preferably, the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 can rotate relative to each other by 0-20 degrees. When the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 are rotated relative to each other by 0 degrees, the contact area between the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 is the largest, and the magnetic circuit is fully connected. At this time, the static bias magnetic field intensity provided is at a maximum value. When the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 are rotated relative to each other by 20 degrees, the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 are no longer in contact with each other, an air gap exists in the magnetic circuit, and the generated magnetic field intensity is at a minimum value.

[0057] In some practical applications, such as Figure 1 As shown, the first circumferential static magnetic field array unit 110 includes only a plurality of second static magnetic field generating elements 112. The plurality of second static magnetic field generating elements 112 are evenly distributed along the circumference of the first circumferential static magnetic field array unit 110. The second circumferential static magnetic field array unit 120 includes only a plurality of fourth static magnetic field generating elements 122. The plurality of fourth static magnetic field generating elements 122 are evenly distributed along the circumference of the second circumferential static magnetic field array unit 120. A portion of the top of each second static magnetic field generating element 112 covers a portion of the top of a fourth static magnetic field generating element 122.

[0058] Preferably, the first circumferential static magnetic field array unit 110 includes four second static magnetic field generating elements 112 , and the second circumferential static magnetic field array unit 120 includes four fourth static magnetic field generating elements 122 .

[0059] use Figure 1 The magnetostrictive longitudinal wave transducer structure 100 shown in the figure, which can realize static magnetic field regulation, is simulated using simulation software. In the first step, an excitation signal is applied to input an alternating current into the alternating magnetic field generating unit 130 to generate a dynamic alternating magnetic field, which is coupled with the static magnetic field. Under the action of the positive magnetostrictive effect, magnetostrictive strain is generated inside the grounding rod, and a displacement strain signal is obtained through mechanical field calculation. In the second step, the obtained displacement strain signal is applied to the grounding rod as an input signal to generate vibration inside the grounding rod. Under the action of the static magnetic field, according to the inverse effect of magnetostriction, the magnetic field around the grounding rod changes, causing the alternating magnetic field generating unit 130 to generate an induced voltage signal. The simulation experiment data is post-processed to obtain the displacement distribution of the cross section of the grounding rod in the horizontal direction as shown in the figure below. Figure 2 As shown, the vertical displacement distribution of the cross section of the grounding rod is obtained as Figure 3 As shown, the axial displacement distribution of the cross section of the grounding rod is obtained as Figure 4By comparison, it can be concluded that the displacement in the axial direction is the largest, far greater than the displacement in the other two directions. This proves that under the combined action of the static bias magnetic field and the dynamic bias magnetic field, the mechanical vibration inside the grounding rod is mainly axial vibration, and the generated vibration is indeed a longitudinal modal guided wave, verifying the feasibility of the transducer structure.

[0060] When only the influence of the static bias magnetic field is considered without considering the influence of the dynamic bias magnetic field, the physical field only retains the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120, and no longer retains the alternating magnetic field generating unit 130. When the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120 move toward each other by 10 mm ( Figure 7 Medium red curve), 20mm ( Figure 7 medium green curve) and 30mm ( Figure 7 When the screw connection lengths of the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120 are 10 mm, 20 mm, and 30 mm, the magnetic field distribution on the central axis of the grounding rod is as follows: Figure 7 As shown in the figure, the axial magnetic field strength is greatly enhanced with the increase of the screw connection length. However, due to the different magnetic path lengths in the radial direction, the magnetic field distribution is significantly deflected, which reduces the conversion efficiency and affects the stability of the excited waveguide.

[0061] In other practical applications, such as Figure 5 As shown, the first circumferential static magnetic field array unit 110 includes a plurality of first static magnetic field generating elements 111 and a plurality of second static magnetic field generating elements 112. The plurality of first static magnetic field generating elements 111 and the plurality of second static magnetic field generating elements 112 are alternately arranged along the circumference of the first circumferential static magnetic field array unit 110. The second circumferential static magnetic field array unit 120 includes a plurality of third static magnetic field generating elements 121 and a plurality of fourth static magnetic field generating elements 122. The plurality of third static magnetic field generating elements 121 and the plurality of fourth static magnetic field generating elements 122 are alternately arranged along the circumference of the second circumferential static magnetic field array unit 120. A portion of the top of each third static magnetic field generating element 121 covers a portion of the top of a first static magnetic field generating element 111. A portion of the top of each second static magnetic field generating element 112 covers a portion of the top of a fourth static magnetic field generating element 122.

[0062] Preferably, the first circumferential static magnetic field array unit 110 includes two first static magnetic field generators 111 and two second static magnetic field generators 112 . The second circumferential static magnetic field array unit 120 includes two third static magnetic field generators 121 and two fourth static magnetic field generators 122 .

[0063] When only the influence of the static bias magnetic field is considered without considering the influence of the dynamic bias magnetic field, the physical field only retains the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120, and no longer retains the alternating magnetic field generating unit 130. When the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120 move toward each other by 10 mm ( Figure 8 Medium red curve), 20mm ( Figure 8 medium green curve) and 30mm ( Figure 8 When the screw connection lengths of the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120 are 10 mm, 20 mm, and 30 mm, the magnetic field distribution on the central axis of the grounding rod is as follows: Figure 8 As the screw connection length increases, the axial magnetic field strength is greatly enhanced, and the axial magnetic field strength is evenly distributed, which improves the energy conversion efficiency.

[0064] When the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120 rotate 5° relative to each other ( Figure 9 Medium blue curve), 10° ( Figure 9 Medium green curve), 15° ( Figure 9 The red curve in the middle shows the magnetic field distribution on the central axis of the grounding rod. Figure 9 As shown in Figure 2, the axial magnetic flux density shows a downward trend as the relative rotation angle increases.

[0065] Specifically, in the example, Figure 5As shown, each first static magnetic field generator 111 includes a first permanent magnet 1111, a first converging armature 1112, a first transfer armature 1113, and a first deflection armature 1114. The first converging armature 1112 is fixedly mounted to the bottom of the first permanent magnet 1111 and can be attached to the outer wall of the component to be detected 200, acting as a magnetic conductor. This allows the same first permanent magnet 1111 to be compatible with grounding rods of various diameters, improving the versatility of the magnetostrictive longitudinal wave transducer structure 100 capable of static magnetic field regulation. The first transfer armature 1113 is fixedly mounted to the top of the first permanent magnet 1111. It acts as a magnetic conductor and connects the first permanent magnet 1111 to the first deflection armature 1114. One end of the first deflection armature 1114 is fixedly mounted to the top of the first transfer armature 1113, while the other end extends toward the third static magnetic field generator 121. The top surface of the first deflection armature 1114 is provided with an upper thread, acting as a magnetic conductor. Each third static magnetic field generating element 121 includes a second permanent magnet 1211, a second converging armature piece 1212, a second transfer armature piece 1213, a raised armature piece 1214, and a second steering armature piece 1215. The second converging armature piece 1212 is fixedly mounted on the bottom of the second permanent magnet 1211 and can be attached to the outer wall of the component to be detected 200, playing a magnetic conduction role. This allows the same second permanent magnet 1211 to be applicable to grounding rods of various diameters, thereby improving the versatility of the magnetostrictive longitudinal wave transducer structure 100 capable of achieving static magnetic field regulation. The second transfer armature piece 1213 is fixedly mounted on the top of the second permanent magnet 1211 and plays a magnetic conduction role. The raised armature piece 1214 is fixedly mounted on the top of the second transfer armature piece 1213 so that the second steering armature piece 1215 is higher than the first steering armature piece 1114. One end of the second steering armature piece 1215 is fixedly mounted on the top of the raised armature piece 1214, and the other end extends toward the first static magnetic field generating element 111. A lower thread is provided on the bottom surface. A portion of the second steering armature piece 1215 is connected to a portion of the first steering armature piece 1114 via a lower thread and an upper thread. The structure of each second static magnetic field generating element 112 is the same as that of each third static magnetic field generating element 121. The structure of each fourth static magnetic field generating element 122 is the same as that of each first static magnetic field generating element. A portion of the second steering armature piece 1215 of each second static magnetic field generating element 112 is connected to a portion of the first steering armature piece 1114 of each fourth static magnetic field generating element 122 via a lower thread and an upper thread. The use of a screw connection facilitates both the movement of the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110 toward each other and the relative rotation of the second circumferential static magnetic field array unit 120 and the first circumferential static magnetic field array unit 110.

[0066] Preferably, the interior of each first static magnetic field generating member 111 , the interior of each second static magnetic field generating member 112 , the interior of each third static magnetic field generating member 121 , and the interior of each fourth static magnetic field generating member 122 are integrally fixed by welding.

[0067] Preferably, the thickness of the first steering armature piece 1114 and the second steering armature piece 1215 is less than or equal to 5 mm to prevent the magnetic field on the axis of the grounding rod from being offset.

[0068] Preferably, the first converging armature piece 1112, the first transfer armature piece 1113, the first steering armature piece 1114, the second converging armature piece 1212, the second transfer armature piece 1213, the spacer armature piece 1214, and the second steering armature piece 1215 are all made of soft magnetic materials. The first permanent magnet 1111 and the second permanent magnet 1211 are neodymium iron boron or other types of permanent magnets.

[0069] Preferably, if Figure 6 As shown, the first circumferential static magnetic field array unit 110 also includes a first support ring 113. A first mounting groove for mounting the first static magnetic field generator 111 and a second mounting groove for mounting the second static magnetic field generator 112 are formed on the inner wall of the first support ring 113. The second circumferential static magnetic field array unit 120 includes a second support ring 123. The first support ring 113 can drive the first static magnetic field generator 111 and the second static magnetic field generator 112 to rotate synchronously. A third mounting groove for mounting the third static magnetic field generator 121 and a fourth mounting groove for mounting the fourth static magnetic field generator 122 are formed on the inner wall of the second support ring 123. The second support ring 123 can drive the third static magnetic field generator 121 and the fourth static magnetic field generator 122 to rotate synchronously.

[0070] Preferably, the first support ring 113 and the second support ring 123 are made of non-ferromagnetic materials such as aluminum alloy or nylon.

[0071] Preferably, multiple first support segments 1131 are sequentially connected to form the first support ring 113. Two adjacent first support segments 1131 are detachably connected via first connecting blocks 1132 and screws to facilitate assembly and disassembly of the first support ring 113. Multiple second support segments 1231 are sequentially connected to form the second support ring 123. Two adjacent second support segments 1231 are detachably connected via second connecting blocks 1232 and screws to facilitate assembly and disassembly of the second support ring 123.

[0072] When the first circumferential static magnetic field array unit 110 includes two first static magnetic field generators 111 and two second static magnetic field generators 112, and the second circumferential static magnetic field array unit 120 includes two third static magnetic field generators 121 and two fourth static magnetic field generators 122, the length of the first steering armature piece 1114 of each first static magnetic field generator 111 is 80 mm, the length of the second steering armature piece 1215 of each third static magnetic field generator 121 is 120 mm, and the length of the threaded engagement is 60 mm, the maximum axial length of the magnetostrictive longitudinal wave transducer structure 100 capable of static magnetic field regulation is 200 mm. Simulation experiments were conducted using simulation software, setting the grounding rod diameter to 30 mm and the material of the grounding rod to Q345 steel. The threaded connection was considered to be surface contact of the armature. The materials of the first permanent magnet 1111 and the second permanent magnet 1211 are set to be N52 neodymium iron boron, the direction of the residual magnetic flux density is radial, and the magnetic poles of the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120 are in opposite directions. The corresponding distribution of the magnetic field under the condition of the parametric scan indentation of 10mm, 20mm, 30mm, etc. is obtained. Figure 10 The polar coordinate diagram of the magnetic field distribution at the middle position of the grounding rod segment covered by the magnetostrictive longitudinal wave transducer structure 100 that can realize static magnetic field regulation is shown. Figure 10 It can be seen that as the length of the axial magnetic circuit decreases, the axial magnetic field distribution inside the grounding rod becomes more uniform, and the magnetic field intensity is greatly improved, which is very beneficial for the generation of stress waves in the magnetostrictive effect. In actual field applications, considering the complex situation where one section of the grounding rod is in the air and the other section is in the paddy field, in such cases, the magnetostrictive longitudinal wave transducer structure 100 that can achieve static magnetic field adjustment can still solve practical problems well. In addition, the specifications of the coil used in the alternating magnetic field generating unit 130 are usually selected according to the required wavelength. For example, the wavelength is about 100mm at a frequency of 50kHz, and about 140mm at a frequency of 35kHz. Therefore, the retraction of the axial magnetic circuit is beneficial to the expansion of the coil frequency, thereby enhancing the detection capability of defects. Through this structure, the magnetic field intensity provided by the static magnetic field array can theoretically be within the maximum threshold corresponding to 0~20°, greatly improving the energy conversion efficiency of the permanent magnet, while overcoming the disadvantage that the magnetic field size of the permanent magnet cannot be adjusted in real time.

[0073] Reference Figure 11On the other hand, the present invention also provides a defect detection device, comprising a signal generating module 310, a power amplifying module 320, a signal amplifying module 330, a signal processing module 340, and a magnetostrictive longitudinal wave transducer structure 100 capable of adjusting a static magnetic field. The magnetostrictive longitudinal wave transducer structure 100 capable of adjusting a static magnetic field is provided with a signal excitation end and a signal receiving end. The alternating magnetic field generating unit 130 is connected to the signal excitation end and the signal receiving end, respectively. The signal excitation end is connected to the power amplifying module 320 and the signal generating module 310 in sequence. The signal receiving end is connected to the signal amplifying module 330 and the signal processing module 340 in sequence. By rotating the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120, the armature is driven to move toward each other, shortening the length of the magnetic circuit and improving the uniformity and strength of the magnetic field. Simultaneously, by adjusting the magnitude of the axial magnetic field, the magnetostrictive effect is optimized, thus overcoming the bottleneck of the unadjustable static magnetic field strength. The overall operation is simple, energy conversion efficiency is significantly improved, and it is suitable for corrosion detection of grounding rods.

[0074] Because pulse-echo is often used in field applications, a magnetostrictive longitudinal wave transducer structure 100 capable of static magnetic field regulation was placed at the left end of the grounding rod, 0.2 m from the left end face. The grounding rod specimen had a diameter of 30 mm and a length of 2 m, with a 2 mm groove engraved at the 1.2 m position. Figure 5 or Figure 6 When the magnetostrictive longitudinal wave transducer structure 100 capable of realizing static magnetic field regulation is working, a pulse echo is excited to the right end face of the grounding rod, and the result is Figure 12 As shown in the echo signal diagram, an obvious defect signal appears at about 1 m, and as the first circumferential static magnetic field array unit 110 and the second circumferential static magnetic field array unit 120 rotate and separate, the amplitude of the defect echo signal becomes lower and lower, which is consistent with the simulation results.

[0075] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0076] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0077] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0078] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0079] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation, characterized in that: include: A first circumferential static magnetic field array unit is formed on the periphery of the object to be detected; a second circumferential static magnetic field array unit, formed on the periphery of the part to be detected and arranged opposite to the first circumferential static magnetic field array unit; the second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit are movable toward each other; and the second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit are relatively rotatable; The alternating magnetic field generating unit is provided between the second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit, and is wound around the periphery of the component to be detected.

2. The magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation according to claim 1, characterized in that: The second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit can move toward each other by 0-40 mm.

3. The magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation according to claim 1, characterized in that: The second circumferential static magnetic field array unit and the first circumferential static magnetic field array unit can rotate relative to each other by 0-20 degrees.

4. The magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field adjustment according to any one of claims 1 to 3, characterized in that: The first circumferential static magnetic field array unit includes: a plurality of first static magnetic field generating elements uniformly distributed along the circumference of the first circumferential static magnetic field array unit; a plurality of second static magnetic field generating elements, arranged alternately with the first static magnetic field generating elements along the circumference of the first circumferential static magnetic field array unit; The second circumferential static magnetic field array unit includes: a plurality of third static magnetic field generating members uniformly distributed along the circumference of the second circumferential static magnetic field array unit; a plurality of fourth static magnetic field generating elements, arranged alternately with the third static magnetic field generating elements along the circumference of the second circumferential static magnetic field array unit; A portion of the top of each of the third static magnetic field generating elements covers a portion of the top of one of the first static magnetic field generating elements; a portion of the top of each of the second static magnetic field generating elements covers a portion of the top of one of the fourth static magnetic field generating elements.

5. The magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation according to claim 4, characterized in that: Each first static magnetic field generating element comprises: a first permanent magnet; A first converging armature piece is fixedly mounted on the bottom of the first permanent magnet and can be attached to the outer wall of the to-be-detected component; a first transferring armature piece is fixedly mounted on the top of the first permanent magnet; The first steering armature piece has one end fixedly mounted on the top of the first transfer armature piece and the other end facing the third static magnetic field The generating member is extended and has an upper thread on its top surface; Each third static magnetic field generating element comprises: a second permanent magnet; A second converging armature piece is fixedly mounted on the bottom of the second permanent magnet and can be attached to the outer wall of the part to be detected; a second transferring armature piece is fixedly mounted on the top of the second permanent magnet; The armature piece is raised and fixedly mounted on the top of the second transfer armature piece; A second steering armature piece, one end of which is fixedly mounted on the top of the raised armature piece, the other end of which extends toward the first static magnetic field generating element, and a bottom surface of which is provided with a lower thread; a portion of the second steering armature piece is connected to a portion of the first steering armature piece via the lower thread and the upper thread; The structure of each of the second static magnetic field generating members is the same as the structure of each of the third static magnetic field generating members; the structure of each of the fourth static magnetic field generating members is the same as the structure of each of the first static magnetic field generating members; a portion of the second steering armature piece of each of the second static magnetic field generating members is connected to a portion of the first steering armature piece of each of the fourth static magnetic field generating members through the lower thread and the upper thread.

6. The magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation according to claim 4, characterized in that: The first circumferential static magnetic field array unit further includes: a first supporting ring, having an inner wall formed with a first mounting groove for mounting the first static magnetic field generating element and a second mounting groove for mounting the second static magnetic field generating element; The second circumferential static magnetic field array unit includes: The second supporting ring has an inner wall formed with a third mounting groove for mounting the third static magnetic field generating component and a fourth mounting groove for mounting the fourth static magnetic field generating component.

7. The magnetostrictive longitudinal wave transducer structure capable of realizing static magnetic field regulation according to claim 6, characterized in that: A plurality of first support segments are sequentially connected to form the first support ring; A plurality of second support segments are connected in sequence to form the second support ring.

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