Cooling fin welding seam ultrasonic detection device and detection method

Abstract

The invention provides a cooling fin weld joint ultrasonic detection device and detection method. The ultrasonic detection device for the welding seam of the cooling fin comprises a frame main body, the connecting mechanism is connected with the frame body through the elastic mechanism, and the connecting mechanism can reciprocate in the first direction through the elastic mechanism; the ultrasonic detection wheel is used for detecting a welding seam of the cooling fin weldment, and the ultrasonic detection wheel is rotationally connected with the connecting mechanism, so that the ultrasonic detection wheel can rotate by taking the connecting mechanism as a central shaft; the auxiliary wheel and the ultrasonic detection wheel are oppositely arranged in the first direction and rotationally connected with the frame body, and the ultrasonic detection wheel and the auxiliary wheel are arranged on the two sides of the cooling fin weldment and synchronously roll along the surface of the cooling fin weldment; under the action of the elastic mechanism, the first distance between the first peripheral surface of the ultrasonic detection wheel and the second peripheral surface of the auxiliary wheel can be adjusted according to the thickness of the cooling fin weldment, and in the initial state, the first distance is not larger than the thickness of the cooling fin weldment.

Description

Technical Field

[0001] This application relates to the field of weld inspection technology, and in particular to an ultrasonic inspection device and method for heat sink welds. Background Technology

[0002] Heat sinks are key components of the cooling systems for oil-immersed transformers and reactors. They dissipate operating heat through natural convection or forced air cooling to maintain a safe operating temperature. Their structure consists of upper and lower oil collection pipes and a corrugated heat sink in the middle. Hot oil enters from the top and flows back to the oil tank from the bottom after cooling. The heat sinks are made of thin-walled, high-thermal-conductivity cold-rolled steel sheets, formed and automatically resistance-welded. A typical 220kV transformer is equipped with approximately 250 heat sinks; the large number of welds means that the welding quality directly affects the long-term safe operation of the equipment.

[0003] Currently, the quality of heat sink welds mainly relies on visual inspection and hydrostatic testing. The former can only detect surface defects, while the latter can only detect through-hole defects and cannot identify internal non-through-hole defects such as lack of fusion. While the hydrostatic test results for such defects may be acceptable, long-term operation under oil pressure and thermal stress may cause the lack of fusion to expand, leading to insulating oil leakage. Furthermore, the hydrostatic testing process is complex and time-consuming. Therefore, existing heat sink weld inspection methods have significant limitations. Summary of the Invention

[0004] The purpose of this application is to provide an ultrasonic testing device for heat sink welds to address the shortcomings of existing weld testing technologies in terms of defect detection capability, efficiency, and reliability.

[0005] To address the aforementioned technical problems, this application provides the following technical solutions: This application provides an ultrasonic testing device for heat sink welds, comprising: a frame body; a connecting mechanism and an elastic mechanism, wherein the connecting mechanism is connected to the frame body via the elastic mechanism and is capable of reciprocating along a first direction via the elastic mechanism; an ultrasonic testing wheel for testing the welds of the heat sink weldment, the ultrasonic testing wheel being rotatably connected to the connecting mechanism so that the ultrasonic testing wheel can rotate about the connecting mechanism as a central axis; and an auxiliary wheel, the auxiliary wheel being disposed opposite to the ultrasonic testing wheel along the first direction and rotatably connected to the frame body, the ultrasonic testing wheel and the auxiliary wheel being symmetrically disposed on both sides of the thickness direction of the heat sink weldment and rolling synchronously along the surface of the heat sink weldment; wherein, under the action of the elastic mechanism, a first distance between the first outer peripheral surface of the ultrasonic testing wheel and the second outer peripheral surface of the auxiliary wheel can be adjusted according to the thickness of the heat sink weldment, and in the initial state, the first distance is not greater than the thickness of the heat sink weldment.

[0006] In some embodiments of this application, the second outer peripheral surface of the auxiliary wheel is provided with a magnetic layer or an adhesive layer, and the auxiliary wheel can generate adhesion when in contact with the surface of the heat sink weldment.

[0007] In some embodiments of this application, the elastic mechanism includes a pair of elastic elements and a guide structure. The guide structure is arranged along the first direction, and the pair of elastic elements are arranged opposite to each other on both sides of the guide structure. The connecting mechanism is a columnar structure arranged along the second direction. The ultrasonic testing wheel is sleeved on the outer periphery of the connecting mechanism. The pair of elastic elements are symmetrically arranged on both sides of the ultrasonic testing wheel along the length direction of the connecting mechanism. The connecting mechanism and the guide structure are slidably connected along the first direction. The first direction and the second direction are perpendicular to each other.

[0008] In some embodiments of this application, the ultrasonic testing wheel includes a wheel body, a piezoelectric crystal, and a signal transmission device. The wheel body is rotatably connected to the connecting mechanism. The piezoelectric crystal is arranged circumferentially around the wheel body, and the side of the piezoelectric crystal facing away from the wheel body forms the first outer peripheral surface. The piezoelectric crystal and the signal transmission device are electrically connected so that the piezoelectric crystal can receive or send detection signals to the ultrasonic testing instrument through the signal transmission device.

[0009] In some embodiments of this application, the ultrasonic testing wheel further includes a damping block and a protective film. The wheel body is a shell structure, and the shell structure and the connecting mechanism form a cavity. The damping block is disposed in the cavity and fixedly connected to the wheel body. The protective film surrounds and covers the first outer peripheral surface of the piezoelectric wafer, and the piezoelectric wafer is clamped between the damping block and the protective film.

[0010] In some embodiments of this application, the signal transmission device includes: a rotating member disposed within the cavity and fixedly connected to the wheel body, the rotating member being sleeved on the outer periphery of the connecting mechanism; a conductive slip ring disposed on the side wall of the connecting mechanism, the rotating member having an annular groove on its surface facing the connecting mechanism, the conductive slip ring having an arc-shaped protrusion facing the cavity, the rotating member covering the conductive slip ring and being connected to it through the annular groove and the arc-shaped protrusion, so that the rotating member can rotate relative to the conductive slip ring; and a first wire located within the cavity, the rotating member... The moving part has a threading channel extending radially through it, which communicates with the annular groove. One end of the first wire is connected to the piezoelectric wafer, and the other end passes through the threading channel and slides in contact with the arc-shaped protrusion. The second wire is connected to a hollow tubular structure. The conductive slip ring is disposed through the side wall of the connecting mechanism. One end of the connecting mechanism along its length has a wire outlet. One end of the second wire extends into the interior of the connecting mechanism and is connected to the conductive slip ring. The other end extends out of the connecting mechanism through the wire outlet for communication connection with the ultrasonic detector.

[0011] In some embodiments of this application, the ultrasonic testing device for heat sink welds further includes: a handle; the frame body has an installation space; the ultrasonic testing wheel and the auxiliary wheel are disposed within the installation space; and the handle is disposed on the side of the frame body facing away from the installation space.

[0012] This application also provides a detection method using the aforementioned ultrasonic testing device for heat sink welds, comprising: connecting the ultrasonic testing device for heat sink welds to an ultrasonic testing instrument, setting the scanning ratio of the ultrasonic testing instrument to 1:1, and ensuring the detection sound path range covers at least twice the thickness of the heat sink; using the echo or bottom wave of an artificial reflector at a depth of twice the thickness of the heat sink as a reference signal, and setting the detection sensitivity; placing the ultrasonic testing device for heat sink welds on the heat sink weld, aligning the ultrasonic testing wheel with the weld width of the heat sink weld, and making the ultrasonic testing wheel contact the surface of the heat sink weld; pushing the ultrasonic testing device for heat sink welds to roll along the weld length direction of the heat sink weld; determining defects based on changes in the echo or bottom wave signal of the artificial reflector at a depth of twice the thickness of the heat sink, and determining that the weld has an unqualified defect if the amplitude of the echo or bottom wave signal of the artificial reflector is lower or disappears compared to the reference signal.

[0013] In some embodiments of this application, setting the detection sensitivity includes: selecting an artificial reflector on a carbon steel comparison test block with a depth covering at least twice the thickness of the heat sink, creating a distance-amplitude curve, and increasing it by 6dB; or, setting the ultrasonic testing device for the heat sink weld in the qualified weld area of ​​the heat sink weld, aligning the ultrasonic testing wheel with the weld width of the heat sink weld, reciprocating the ultrasonic testing wheel at least one revolution, adjusting the average amplitude of the bottom wave signal at a depth of twice the thickness of the heat sink to 80% of the full scale of the ultrasonic testing instrument display, and then increasing it by 6dB.

[0014] In some embodiments of this application, the method of determining defects by the change in the echo or bottom wave signal of the artificial reflector at a depth of twice the thickness of the heat sink includes: if the amplitude of the echo of the artificial reflector at a depth of twice the thickness of the heat sink is lower than the corresponding height according to the distance-amplitude curve, then the weld is determined to have an unqualified defect; or, if the amplitude of the bottom wave signal at a depth of twice the thickness of the heat sink is lower than 40% of the full scale of the display screen, or the bottom wave signal disappears completely, then the weld is determined to have an unqualified defect.

[0015] Compared to existing technologies, the ultrasonic testing device for heat sink welds provided in this application achieves stable clamping and good acoustic coupling by placing the ultrasonic testing wheel and auxiliary wheel on opposite sides of the weldment and utilizing an elastic mechanism to allow the ultrasonic testing wheel to adaptively float in a direction perpendicular to the weldment surface. Simultaneously, the ultrasonic testing wheel can roll along the weld with the device, continuously performing ultrasonic scanning. This eliminates the need to rely on leakage paths and solves problems in existing technologies such as blind spots, unstable signals, and low detection rates caused by surface unevenness, variations in weldment thickness, or poor coupling. It significantly improves the reliability, applicability, and efficiency of the testing, making it particularly suitable for batch factory inspection and on-site inspection of equipment such as transformers. Attached Figure Description

[0016] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein: Figure 1 A schematic diagram of the structure of the ultrasonic testing device for heat sink welds in Embodiment 1 of this application is shown. Figure 2 A schematic left view of the ultrasonic testing device for heat sink welds according to Embodiment 1 of this application is shown. Figure 3 The diagram schematically shows a right view of the ultrasonic testing device for heat sink welds according to Embodiment 1 of this application; Figure 4The diagram schematically illustrates the internal structure of the ultrasonic testing wheel in the ultrasonic testing device for heat sink welds according to Embodiment 1 of this application. Figure 5 The diagram illustrates the usage status of the ultrasonic testing device for heat sink welds in Embodiment 1 of this application. Figure 6 This schematic diagram illustrates the ultrasonic testing device for heat sink welds in Embodiment 1 of this application from another perspective, showing its usage status. Figure 7 A schematic diagram illustrating the principle of the detection method of Embodiment 2 of this application is shown. Explanation of icon numbers: 1. Frame body; 2. Connecting mechanism; 3. Elastic mechanism; 301. Elastic element; 302. Guide structure; 4. Ultrasonic testing wheel; 401. Wheel body; 402. Piezoelectric crystal; 403. Damping block; 404. Protective film; 405. Rotating element; 406. Wire threading channel; 407. Conductive slip ring; 408. First wire; 409. Second wire; 5. Auxiliary wheel; 6. Handle; 100. Heat sink weldment; 1001. Heat sink; 1002. Weld; 200. Ultrasonic testing instrument. Detailed Implementation

[0017] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0018] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains.

[0019] As a key component of the cooling system for oil-immersed transformers and reactors, heat sinks are made of thin-walled, high-thermal-conductivity cold-rolled steel sheets through automatic resistance welding, resulting in a large number of welds per unit. However, existing inspection methods, such as visual inspection and hydrostatic testing, can only identify surface defects or through-hole leaks, failing to effectively detect internal non-through-hole defects such as lack of fusion, posing serious safety hazards. Although rolling ultrasonic testing devices exist, heat sinks typically have a corrugated structure with varying weld curvature and narrow spacing. Existing devices struggle to automatically conform the ultrasonic probes to complex surfaces and cannot dynamically adjust the clamping force according to the sheet thickness, easily leading to poor coupling and affecting the stability of the ultrasonic signal and the defect detection rate.

[0020] To address the aforementioned issues, this application proposes an ultrasonic testing device specifically for heat sink welds. Its core lies in employing a mechanical structure with elastic floating and symmetrical double-wheel clamping, achieving adaptive, stable, and continuous ultrasonic coupling. When the weldment is inserted between the ultrasonic testing wheel and the auxiliary wheel, the elastic mechanism automatically adjusts the distance between the two wheels according to its actual thickness, generating a moderate clamping force while ensuring the initial distance does not exceed the weldment thickness, thus guaranteeing that the probe maintains good contact with the weld surface. Compared to existing technologies, this solution requires no external power or active adjustment, features a simple structure, high response, and high reliability, making it particularly suitable for automated online inspection of large batches of thin-walled welds. It effectively solves key technical bottlenecks such as low internal defect detection rate, poor detection efficiency, and unstable coupling.

[0021] Example 1 This application provides an ultrasonic testing device for heat sink welds, such as... Figures 1 to 3 As shown, it includes: a frame body 1; a connecting mechanism 2 and an elastic mechanism 3, wherein the connecting mechanism 2 is connected to the frame body 1 through the elastic mechanism 3, and the connecting mechanism 2 can reciprocate along a first direction through the elastic mechanism 3; an ultrasonic testing wheel 4, used to test the weld 1002 of the heat sink weldment 100, the ultrasonic testing wheel 4 is rotatably connected to the connecting mechanism 2 so that the ultrasonic testing wheel 4 can rotate about the connecting mechanism 2 as the central axis; an auxiliary wheel 5, the auxiliary wheel 5 is arranged opposite to the ultrasonic testing wheel 4 along the first direction and is rotatably connected to the frame body 1, the ultrasonic testing wheel 4 and the auxiliary wheel 5 can be symmetrically arranged on both sides of the thickness direction of the heat sink weldment 100, and roll synchronously along the surface of the heat sink weldment 100; wherein, under the action of the elastic mechanism 3, the first distance between the first outer peripheral surface of the ultrasonic testing wheel 4 and the second outer peripheral surface of the auxiliary wheel 5 can be adjusted according to the thickness of the heat sink weldment 100, and in the initial state, the first distance is not greater than the thickness of the heat sink weldment 100.

[0022] The main frame 1 serves as the supporting structure for the entire ultrasonic testing device, used for mounting and securing other functional modules. The main frame 1 can be made of lightweight yet robust materials, such as aluminum alloy or engineering plastics, to provide a mounting reference for other components and ensure overall rigidity and stability.

[0023] The connecting mechanism 2 is used to mount the ultrasonic testing wheel 4, for example, a wheel frame or axle seat, to provide support for the ultrasonic testing wheel 4. The connecting mechanism 2 is connected to the frame body 1 via an elastic mechanism 3, which can be a spring or an elastic arm, allowing the connecting mechanism 2 to reciprocate in a first direction, which can be perpendicular to the surface of the heat sink weldment 100. The elastic mechanism 3 can apply appropriate clamping force to ensure that the ultrasonic testing wheel 4 is always tightly fitted to the surface of the heat sink weldment 100 and can adapt to weldments of different thicknesses or slight unevenness.

[0024] The ultrasonic testing wheel 4 can emit and receive ultrasonic signals for non-destructive testing of the interior of the weld 1002. The ultrasonic testing wheel 4 is rotatably connected to the connecting mechanism 2, allowing it to rotate freely about the connecting mechanism 2 as its axis, facilitating its rolling along the length of the weld 1002.

[0025] The auxiliary wheel 5 and the ultrasonic testing wheel 4 are arranged opposite to each other in the first direction, and the auxiliary wheel 5 is rotatably connected to the frame body 1, so that the auxiliary wheel 5 and the ultrasonic testing wheel 4 can be located on opposite sides of the heat sink weldment 100. The connecting mechanism 2 can be a pair, one of which is rotatably connected to the ultrasonic testing wheel 4 and the other is rotatably connected to the auxiliary wheel 5. The diameter and width of the auxiliary wheel 5 can be consistent with those of the ultrasonic testing wheel 4. The initial distance between the outer peripheral surfaces of the auxiliary wheel 5 and the ultrasonic testing wheel 4, i.e., the first distance, is not greater than the thickness of the heat sink weldment 100, so that under the action of the elastic mechanism 3, the ultrasonic testing wheel 4 can automatically clamp the heat sink weldment 100 and maintain good coupling.

[0026] The auxiliary wheels 5 can be two or more, forming a multi-point support structure. The multi-point support structure not only enhances the balance of the detection device during the rolling detection process and effectively suppresses shaking or displacement caused by local undulations, corrugation deformation or manufacturing tolerances of the weld, but also applies clamping force more evenly, avoiding probe tilting or decoupling caused by single-point force.

[0027] In use, the operator can hold or electrically drive the frame body 1 to place the ultrasonic testing device in the weld seam 1002 area of ​​the heat sink weldment 100, and make the ultrasonic testing wheel 4 and the auxiliary wheel 5 contact the two sides of the weldment respectively. Under the clamping force provided by the elastic mechanism 3, the two wheels can automatically stick together and roll synchronously. The operator only needs to push the ultrasonic testing device along the direction of the weld seam 1002 to complete the inspection. As the ultrasonic testing device moves, the ultrasonic testing wheel 4 can continuously perform ultrasonic scanning on the weld seam 1002, effectively detecting internal defects such as lack of fusion.

[0028] The ultrasonic testing device provided in this application embodiment does not rely on leakage paths and can achieve full 1002 weld seam coverage testing using ultrasonic waves, significantly improving defect detection rate and testing reliability. Simultaneously, the ultrasonic testing device supports handheld operation or automatic walking mode, suitable for batch factory inspection and daily patrol inspection of equipment such as transformers, greatly improving testing efficiency and reducing labor costs and testing time. Furthermore, the elastic mechanism 3 ensures that the ultrasonic testing wheel 4 maintains a constant and appropriate contact pressure on various curved or uneven surfaces, thereby guaranteeing effective transmission of ultrasonic signals and the repeatability and accuracy of test results.

[0029] In some embodiments, the second outer peripheral surface of the auxiliary wheel 5 is provided with a magnetic layer or an adhesive layer, and the auxiliary wheel 5 can generate adhesion when in contact with the surface of the heat sink weldment 100.

[0030] The outer periphery of the auxiliary wheel 5, i.e., the side in contact with the surface of the heat sink weldment 100, can be covered with a layer of magnetic material, such as rubber magnet or ferrite composite material. Alternatively, a ring-shaped permanent magnet can be embedded inside the wheel core to give the entire wheel surface a uniform magnetic attraction. When the heat sink 1001 is made of ferromagnetic material (such as conventional cold-rolled steel), the auxiliary wheel 5 can be magnetically attracted to the back of the weldment, providing stable reverse support. For non-ferromagnetic materials (such as stainless steel), the outer periphery of the auxiliary wheel 5 can be covered with an adhesive material, such as silicone, polyurethane, or double-sided tape, to generate appropriate adhesion on the contact surface.

[0031] In practical applications, either a magnetic layer or an adhesive layer can be flexibly selected based on the material of the heat sink 1001. When the ultrasonic testing device is placed on the heat sink weldment 100, the auxiliary wheel 5 can actively adhere to and be fixed to the back of the weldment through magnetic attraction or adhesion, while the ultrasonic testing wheel 4 is pressed against the front of the weld 1002 by the push of the elastic mechanism 3. During the movement along the weld 1002, the two wheels roll synchronously without deviation under the action of clamping force, always maintaining a stable ultrasonic coupling gap.

[0032] The additional adhesion provided by the magnetic or adhesive layer significantly improves the operational stability of the ultrasonic testing device in vertical, inverted, or vibrating environments. The auxiliary wheel 5 works in conjunction with the ultrasonic testing wheel 4 to not only overcome the effects of gravity but also, in conjunction with the elastic mechanism 3, achieve a constant and uniform fit on the surface of the weldment, thereby ensuring the continuity of ultrasonic signal transmission and the reliability of the test results.

[0033] In some embodiments, such as Figure 1 As shown, the elastic mechanism 3 includes a pair of elastic elements 301 and a guide structure 302. The guide structure 302 is arranged along a first direction, and the pair of elastic elements 301 are arranged opposite to each other on both sides of the guide structure 302. The connecting mechanism 2 is a columnar structure arranged along a second direction. The ultrasonic detection wheel 4 is sleeved on the outer periphery of the connecting mechanism 2. The pair of elastic elements 301 are symmetrically arranged on both sides of the ultrasonic detection wheel 4 along the length direction of the connecting mechanism 2. The connecting mechanism 2 and the guide structure 302 are slidably connected along the first direction. The first direction and the second direction are perpendicular to each other.

[0034] The guide structure 302 can take the form of a guide rod, guide rail, or guide cylinder, and is fixed to the frame body 1 along the first direction (i.e., the direction perpendicular to the surface of the heat sink weld 100), providing a straight sliding path for the connecting mechanism 2 and effectively preventing it from deviating or twisting during movement. The connecting mechanism 2 can be a columnar structure extending along a second direction perpendicular to the first direction, such as a round shaft, square shaft, or hollow tube. The ultrasonic testing wheel 4 can be mounted on the outer circumference of the connecting mechanism 2 via a bearing or directly sleeved, and can rotate freely around the second direction, thereby facilitating smooth rolling along the length of the weld 1002.

[0035] Elastic elements 301 (such as compression springs or elastic rubber blocks) are symmetrically arranged on both sides of the guide structure 302 and located on the left and right sides of the ultrasonic testing wheel 4 along the length direction of the connecting mechanism 2 (i.e., the second direction). The two ends of the elastic elements 301 can be fixed to the main frame body 1 and the connecting mechanism 2 respectively by fastening bolts. When the ultrasonic testing device is placed in the weld seam 1002 area of ​​the heat sink 1001, the auxiliary wheel 5 contacts the back of the weldment, and the ultrasonic testing wheel 4 contacts the front. The thickness of the weldment pushes the ultrasonic testing wheel 4 and the connecting mechanism 2 to move along the first direction, thereby compressing the elastic elements 301 on both sides. The elastic elements 301 can generate a reverse elastic force, ensuring that the ultrasonic testing wheel 4 always fits tightly against the surface of the weld seam 1002, ensuring good ultrasonic coupling.

[0036] Under the constraint of the guide structure 302, the connecting mechanism 2 can move linearly along the first direction, avoiding swaying or instability. Even under complex working conditions such as vertical, inverted, or vibrating conditions, the ultrasonic testing device can still ensure reliable operation, ensuring constant contact pressure and continuous ultrasonic signal transmission during the testing process.

[0037] In some embodiments, such as Figure 1 As shown, the guide structure 302 includes a guide rail and a connecting arm. The guide rail is mounted on the frame body 1 along a first direction (i.e., perpendicular to the surface of the heat sink 1001) and can be securely connected by screws, riveting, or integral molding. One end of the connecting arm is slidably engaged with the guide rail via a slider, groove, or other structure, allowing it to move along the guide rail; the other end is rigidly fixed to the connecting mechanism 2, for example, through welding, bolting, or a snap-fit ​​structure to achieve a reliable connection. The linear sliding structure formed by the guide rail and the connecting arm effectively restricts the degree of freedom of the connecting mechanism 2 in directions other than the first direction, preventing it from swaying, twisting, or lateral shaking during the testing process, ensuring that the ultrasonic testing wheel 4 always presses perpendicularly against the surface of the weld 1002, maintaining a stable acoustic coupling state.

[0038] In some embodiments, the ultrasonic testing wheel 4 includes a wheel body 401, a piezoelectric wafer 402, and a signal transmission device. The wheel body 401 is rotatably connected to the connecting mechanism 2. The piezoelectric wafer 402 is arranged around the wheel body 401 in the circumferential direction. The side of the piezoelectric wafer 402 facing away from the wheel body 401 forms a first outer peripheral surface. The piezoelectric wafer 402 and the signal transmission device are electrically connected so that the piezoelectric wafer 402 can receive or send detection signals to the ultrasonic testing instrument 200 through the signal transmission device.

[0039] The ultrasonic testing wheel 4's wheel body 401 can be cylindrical or a cylindrical shell, and can be rotatably connected to the connecting mechanism 2 via bearings or bushings, allowing it to rotate freely around a second direction, facilitating smooth rolling along the weld seam 1002 during testing. A piezoelectric crystal 402, such as PZT ceramic or single-crystal piezoelectric material, is integrated on the outer periphery of the wheel body 401, arranged 360° around the wheel body 401. The width of the piezoelectric crystal 402 can be the same as the width of the weld seam 1002 of the heat sink weldment 100, and it can emit and receive ultrasonic waves with a center frequency of 2.5MHz-5MHz. Its outer surface, i.e., the side facing away from the center of the wheel body 401, constitutes the first outer peripheral surface of the ultrasonic testing wheel 4, directly contacting the surface of the heat sink weldment 100 to ensure good acoustic coupling.

[0040] The signal transmission device can be installed inside or on the surface of the wheel body 401, and is electrically connected to the piezoelectric crystal 402 and the external ultrasonic detector 200, respectively, for bidirectional transmission of electrical signals. It can transmit the high-voltage excitation pulse emitted by the ultrasonic detector 200 to the piezoelectric crystal 402 to excite ultrasonic waves, and can also transmit the echo signal received by the piezoelectric crystal 402 back to the detector in real time for processing and imaging.

[0041] By integrating the piezoelectric chip 402 around the outer periphery of the wheel 401 in a 360° manner and combining it with a signal transmission device, a rolling, continuous scanning, and highly coupled detection structure can be constructed. This not only eliminates blind spots in traditional detection but also significantly improves the defect detection rate and detection efficiency, making it suitable for industrial scenarios with stringent quality requirements for weld 1002.

[0042] In some embodiments, such as Figure 4 As shown, the ultrasonic testing wheel 4 also includes a damping block 403 and a protective film 404. The wheel body 401 is a shell structure, and the shell structure and the connecting mechanism 2 form a cavity. The damping block 403 is disposed in the cavity and fixedly connected to the wheel body 401. The protective film 404 surrounds and covers the first outer peripheral surface of the piezoelectric wafer 402, and the piezoelectric wafer 402 is clamped between the damping block 403 and the protective film 404.

[0043] The wheel body 401 adopts a hollow shell structure, such as a cylindrical or drum-shaped one, which, together with the connecting mechanism 2, forms a closed internal cavity. Within this cavity, a damping block 403 is fixedly installed on the inner side of the wheel body 401, for example, by adhesive bonding or snap-fitting to the inner wall of the wheel body 401, and is tightly fitted to the inner surface of the piezoelectric crystal 402. The damping block 403 can be made of a high-loss, high-acoustic-impedance-matching elastic material, such as rubber, silicone, polyurethane, or a special acoustic damping composite material, to absorb stray vibrations and multiple reflections of sound waves generated by the piezoelectric crystal 402, effectively suppressing ringing effects and thus significantly improving the resolution of the ultrasonic pulse.

[0044] A protective film 404 covers the outer peripheral working surface of the piezoelectric wafer 402. The protective film 404 surrounds and completely covers the outer peripheral surface of the piezoelectric wafer 402, and its edges can be sealed to the wheel body 401, so that the piezoelectric wafer 402 is firmly clamped between the damping block 403 and the protective film 404. The protective film 404 can be made of a thin, flexible, highly wear-resistant and low-sound-attenuation material, such as polyimide, polyurethane film, Teflon or silicone film, to effectively reduce the reflection loss of ultrasonic waves at the interface and improve the sound transmission efficiency.

[0045] By setting the damping block 403, not only can mechanical support be provided for the piezoelectric wafer 402, but its acoustic impedance characteristics, which are similar to those of the piezoelectric wafer 402, can also be used to cause the piezoelectric wafer 402 to stop vibrating quickly after excitation and efficiently absorb the acoustic energy radiated in the reverse direction. At the same time, the protective film 404 can physically protect the piezoelectric wafer 402 from wear or contamination and ensure that the ultrasonic waves are transmitted into the heat sink solder 100 with almost no damage.

[0046] In some embodiments, such as Figure 4 As shown, the signal transmission device includes: a rotating member 405, disposed within the cavity and fixedly connected to the wheel 401, the rotating member 405 being sleeved on the outer periphery of the connecting mechanism 2; a conductive slip ring 407, disposed on the side wall of the connecting mechanism 2, the rotating member 405 having an annular groove on its surface facing the connecting mechanism 2, the conductive slip ring 407 having an arc-shaped protrusion facing the cavity, the rotating member 405 covering the conductive slip ring 407, and being connected to it through the annular groove and the arc-shaped protrusion, so that the rotating member 405 can rotate relative to the conductive slip ring 407; and a first wire 408, located within the cavity, along which the rotating member 405 rotates. A through-hole channel 406 is provided, which is connected to an annular groove. One end of the first wire 408 is connected to the piezoelectric crystal 402, and the other end passes through the through-hole channel 406 and slides in contact with the arc-shaped protrusion. A second wire 409 is provided. The connecting mechanism 2 is a hollow tubular structure. A conductive slip ring 407 is provided through the side wall of the connecting mechanism 2. One end of the connecting mechanism 2 along its length direction is provided with a wire outlet. One end of the second wire 409 extends into the connecting mechanism 2 and is connected to the conductive slip ring 407. The other end extends out of the connecting mechanism 2 through the wire outlet for communication connection with the ultrasonic detector 200.

[0047] The wheel body 401 can adopt a shell structure, forming a closed cavity inside. The connecting mechanism 2 is a cylindrical hollow tube (such as a hollow shaft) that passes through the center of the wheel body 401 along the second direction. The rotating component 405 is installed in the cavity of the wheel body 401 and is fixedly connected to the wheel body 401, so that it can rotate synchronously with the wheel body 401. The rotating component 405 can be annular or sleeve-shaped, and can be a rotating bearing or bushing, sleeved on the outer periphery of the connecting mechanism 2, so that the wheel body 401 is rotatably connected to the connecting mechanism 2 through the rotating component 405.

[0048] A closed annular groove is provided on the side of the rotating component 405 facing the connecting mechanism 2, and a wire passage 406 is provided in the radial direction of the rotating component 405. One end of the wire passage 406 leads to the mounting area of ​​the piezoelectric wafer 402, and the other end connects to the bottom of the annular groove. A conductive slip ring 407 is fixed to the side wall of the connecting mechanism 2 and does not rotate with the wheel 401; a part of it extends into the cavity, and the extended end has an arc-shaped protrusion (such as a semi-circular or crescent-shaped conductive contact). This protrusion is embedded in the annular groove of the rotating component 405 and cooperates with the groove wall to form a mechanical connection and electrical contact interface that can rotate relative to each other. The surface of the arc-shaped protrusion can be made of a highly conductive and wear-resistant material (such as gold-plated copper or silver alloy), which not only ensures a stable and reliable sliding electrical contact with the inner wall of the annular groove, but also restricts the movement of the rotating component 405 and the wheel 401 relative to the length direction of the connecting mechanism 2. When the wheel 401 rotates, the rotating component 405 drives the annular groove to rotate around the arc-shaped protrusion of the conductive slip ring 407. The two always maintain a sliding electrical connection, thereby realizing continuous electrical signal transmission in the rotating state.

[0049] The first wire 408 is located within the cavity of the wheel body 401. One end of it passes through the damping block 403 and is reliably connected to the signal electrode of the piezoelectric crystal 402, while the other end is introduced into the radial wire passage 406 provided on the rotating component 405. Since the wire passage 406 communicates with the internal space of the annular groove, the first wire 408 is guided into the annular groove after passing through the channel and maintains stable sliding electrical contact with the arc-shaped protrusion surface of the conductive slip ring 407. This reliable connection can be achieved, for example, through an elastic metal sheet or direct pressing. Thus, the ultrasonic echo signal generated by the piezoelectric crystal 402 can be transmitted via the first wire 408 to the sliding contact surface within the annular groove, and then conducted out through the conductive slip ring 407. The sidewall of the wire passage 406 abuts against the circumference of the first wire 408, effectively preventing the wire from twisting, tangling, or fatigue-breaking during the rotation of the wheel body 401, ensuring the long-term reliability of the signal path.

[0050] The connecting mechanism 2 is a hollow tubular structure with an outlet at one end along its length. The conductive slip ring 407 is fixed to and penetrates the side wall of the connecting mechanism 2. One end of the second wire 409 is electrically connected to the conductive slip ring 407 inside the connecting mechanism 2, and the other end is led out through the outlet to the outside of the device and connected to the ultrasonic detector 200.

[0051] When the ultrasonic testing device is placed on the weld 1002 for testing, the wheel 401 drives the piezoelectric crystal 402 and the rotating component 405 fixed thereto to rotate and scan around the weld 1002. During this process, the rotating component 405 and its internal first wire 408 continuously rotate relative to the fixed connecting mechanism 2 and the conductive slip ring 407. The electrical signal generated by the piezoelectric crystal 402 is transmitted to the rotating component 405 through the first wire 408, then enters the annular groove through the wire channel 406, and is transmitted to the conductive slip ring 407 through sliding contact with the arc-shaped protrusion of the conductive slip ring 407. Finally, it is led out by the second wire 409 through the hollow connecting mechanism 2 and sent to the external ultrasonic testing instrument 200. Throughout the entire process, no matter how many times the wheel 401 rotates, the signal path remains open.

[0052] Since the first conductor 408 is fixed to the rotating component 405 through the wire passage 406 and does not twist itself, the fatigue fracture problem caused by repeated twisting of traditional conductors is effectively avoided, significantly improving the mechanical reliability and service life of the signal transmission path. Simultaneously, the electrical signal is continuously transmitted from the rotating component to the fixed component through sliding contact, and then stably output through internal wiring, achieving continuous, low-noise, and highly reliable signal transmission during rotation. All signal transmission components are integrated inside the wheel body 401 cavity and the connecting mechanism 2, ensuring not only good sealing but also a stable electrical connection between the piezoelectric crystal 402 and external detection equipment while ensuring the wheel body 401 can rotate freely and infinitely.

[0053] In some embodiments, such as Figure 5 As shown, the ultrasonic testing device for heat sink welds also includes: a handle 6, a frame body 1 having an installation space, an ultrasonic testing wheel 4 and an auxiliary wheel 5 set in the installation space, and a handle 6 set on the side of the frame body 1 facing away from the installation space.

[0054] The main frame 1 can be made of aluminum alloy or engineering plastic, and the overall structure can be designed as U-shaped, C-shaped, or box-shaped. It has an open or semi-enclosed installation space inside to accommodate the ultrasonic testing wheel 4, auxiliary wheel 5, and other testing components. The ultrasonic testing wheel 4 and auxiliary wheel 5 are symmetrically arranged within this installation space, and their dimensions can be set according to the thickness of the heat sink 1001 and the width of the weld 1002 to ensure that the wheel assembly can smoothly clamp the weldment and roll smoothly along the weld 1002.

[0055] A handle 6 is fixedly connected to the side of the frame body 1 facing away from the installation space. The handle 6 can be integrally formed with the frame body 1, for example, by injection molding or machining, or it can be connected separately by bolts or clips, which facilitates disassembly, transportation or replacement.

[0056] During operation, the operator can hold handle 6 with one hand and align the ultrasonic testing device with the weld seam 1002 area of ​​the heat sink weldment 100. Relying on the coordinated action of the elastic mechanism 3 and the auxiliary wheel 5, the ultrasonic testing device automatically clamps the weldment without additional adjustment. Then, the operator simply needs to smoothly push or pull handle 6 along the weld seam 1002 to drive the ultrasonic testing wheel 4 and the auxiliary wheel 5 to roll synchronously, achieving continuous testing. During this process, the ultrasonic signal is transmitted in real time to the external ultrasonic testing instrument 200 through the built-in signal transmission device, thus enabling simultaneous testing and movement. After the test is completed, simply lifting handle 6 allows the ultrasonic testing device to quickly detach from the heat sink weldment 100, ready to proceed to the next testing location.

[0057] By integrating an ergonomically designed handle 6 on the back of the main frame 1, the originally bulky or difficult-to-operate testing equipment can be transformed into a lightweight, intuitive, and efficient handheld tool, significantly improving the convenience of on-site operation and testing efficiency.

[0058] Example 2 This application provides a detection method, such as... Figures 5 to 7 As shown, the ultrasonic testing device for heat sink welds provided in Example 1 includes: Connect the ultrasonic testing device for the heat sink weld to the ultrasonic testing instrument 200, set the scanning ratio of the ultrasonic testing instrument 200 to 1:1, and the detection sound path range covers at least twice the thickness of the heat sink 1001. The detection sensitivity is set by using the echo or bottom wave of an artificial reflector at a depth of twice the thickness of the heat sink (1001mm) as the reference signal. Place the ultrasonic testing device for the heat sink weld on the heat sink weld 100, align the ultrasonic testing wheel 4 with the width of the weld 1002 of the heat sink weld 100, and make the ultrasonic testing wheel 4 contact the surface of the heat sink weld 100. The ultrasonic testing device for the heat sink weld is pushed to roll along the length of the weld 1002 of the heat sink weldment 100; Defects are determined by the change in the echo or bottom wave signal of the artificial reflector at a depth of twice the thickness of the heat sink 1001. If the amplitude of the echo or bottom wave signal of the artificial reflector is reduced or disappears compared with the reference signal, the weld 1002 is determined to have an unqualified defect.

[0059] This application provides an ultrasonic testing method based on the ultrasonic testing device for heat sink welds provided in Embodiment 1 above, which can be used for quality assessment of weld 1002 of heat sink 1001 in oil-immersed transformers or reactors.

[0060] Before testing, the ultrasonic testing device for the heat sink weld is first connected to the ultrasonic testing instrument 200 via a signal transmission device (such as a cable or wireless module). Then, the scanning ratio in the ultrasonic testing instrument 200 is set to 1:1, meaning the depth scale displayed on the screen matches the actual physical depth, facilitating intuitive identification of defect locations by the operator. Since the heat sink weld 100 is composed of two heat sink plates welded together, the detection sound path range should be set to no less than twice the thickness of the heat sink 1001 (2T) to ensure complete capture of bottom echoes and any potential defect signals within the weld 1002.

[0061] Then, the ultrasonic testing device and ultrasonic testing instrument 200 for the heat sink weld are calibrated using a standard test block with an artificial reflector. The artificial reflector, used to simulate typical defects, is crucial for calibrating sensitivity and verifying system performance in ultrasonic testing; therefore, the material and thickness of the artificial reflector test block must be consistent with the heat sink 1001 being tested. The ultrasonic testing device is placed on the test block, and the echo from the artificial reflector at a depth of 2T is used. If the test block is defect-free, the bottom echo can be collected as a reference signal. Based on this, the detection sensitivity is set and locked. This reference signal represents the normal energy level at which ultrasonic waves can successfully penetrate and return in intact material; all subsequent test results are compared against this reference.

[0062] During formal testing, the ultrasonic testing device is placed in the weld 1002 area of ​​the heat sink 100 to be inspected, ensuring that the axis of the ultrasonic testing wheel 4 is approximately aligned with the width direction of the weld 1002, so that the ultrasonic beam can cover the entire cross-section of the weld 1002 to the maximum extent. The coupling method can be direct contact, and the coupling agent is transformer oil of the actual grade used. Relying on the built-in elastic mechanism 3 of the ultrasonic testing device, the ultrasonic testing wheel 4 and the auxiliary wheel 5 automatically clamp the two sides of the weld, ensuring good coupling between the probe and the steel plate surface. Subsequently, the ultrasonic testing device is rolled uniformly along the length of the weld 1002 at a speed not exceeding 150 mm / s to achieve continuous and stable ultrasonic scanning.

[0063] During the rolling scan, the operator needs to observe in real time the reference signal (i.e., bottom wave or artificial reflector echo) located at a depth of 2T on the 200-degree ultrasonic testing instrument screen. For example... Figure 7 As shown, where Figure 7 Figure A shows the weld without internal defects, while Figure B shows the weld with internal defects. Under normal circumstances, ultrasonic waves pass through weld 1002 and reflect off the bottom surface, forming a stable backwave. However, when there is a lack of fusion within weld 1002, it blocks the sound wave energy, causing a significant attenuation of the signal reaching the bottom surface and returning, manifested as a marked decrease or even disappearance of the backwave amplitude. If the reference signal remains stable or only fluctuates slightly, the weld 1002 in that area is considered to be of acceptable quality; if the amplitude significantly decreases or completely disappears, it is determined that there is an unacceptable defect affecting structural integrity.

[0064] The detection method provided in this application establishes a rapid, accurate, and standardized quality assessment process for weld 1002 by scientifically setting the sound path range, using the echo at a depth of 2T as the defect judgment benchmark, and combining it with a dedicated ultrasonic testing device for heat sink welds. Specifically addressing the relatively small thickness of the transformer heat sink 1001, the method avoids the area at depth T that is susceptible to interference from the probe's initial wave, selecting the signal at 2T as the adjustment and judgment criterion. This allows for more sensitive and reliable identification of internal defects hindering sound wave propagation, significantly improving the accuracy and engineering applicability of the detection.

[0065] In some embodiments, setting the detection sensitivity includes: On a carbon steel control block, an artificial reflector with a depth covering at least twice the thickness of the 1001mm heat sink was selected. A distance-amplitude curve was fabricated, and the reflector was improved by 6dB; or, Set the ultrasonic testing device for the heat sink weld seam in the qualified area of ​​weld seam 1002 of heat sink weld 100, align the ultrasonic testing wheel 4 with the width of weld seam 1002 of heat sink weld 100, and move the ultrasonic testing wheel 4 back and forth at least one revolution. Adjust the average amplitude of the bottom wave signal at a depth of 2 times the thickness of heat sink 1001 to 80% of the full scale of the display screen of ultrasonic testing instrument 200, and then increase it by 6dB.

[0066] A standard test block with similar material and acoustic properties to the heat sink 1001 can be selected. This block contains multiple artificial reflectors at different depths, at least one of which is located at a depth greater than twice the thickness of the heat sink 1001 (2T). The ultrasonic testing device is placed on the surface of the test block and aligned with the artificial reflectors, scanning each reflector at different depths sequentially and recording the corresponding echo height. The ultrasonic testing instrument 200 automatically or manually plots a distance-amplitude curve, reflecting the echo attenuation pattern of defects of the same size at different depths. Subsequently, the instrument gain is adjusted so that the echo from the artificial reflector at a depth of 2T falls on the distance-amplitude curve. Based on this, the gain is further increased by 6 dB (decibel) as the final detection sensitivity. This 6 dB gain margin reduces the equivalent size of detectable defects, significantly improving the detection capability for small defects and low-reflectivity planar defects (such as incomplete fusion and microcracks).

[0067] If a standard test block is unavailable in the field or mass production environment, a representative weld area 1002 with known good welding quality and no defects can be selected on the heat sink weldment 100 to be inspected. The ultrasonic testing device is aimed at this weld area 1002 and rolled back and forth along the weld 1002 at least one revolution, collecting bottom echo signals at multiple points at a depth of 2T. The ultrasonic testing instrument 200 automatically calculates the average amplitude of these bottom echo signals and adjusts the gain so that the average amplitude reaches 80% of the full scale of the display screen. After locking this gain, it is then increased by 6dB overall as the sensitivity used for formal testing. This method does not rely on standard test blocks, is simple to operate, and has a rapid response, making it suitable for rapid calibration in field maintenance or production lines. At the same time, the 6dB margin ensures sufficient detection sensitivity and reliability for weak reflections or hidden defects.

[0068] Both methods use a 2T depth signal as a reference and build a reasonable detection margin by increasing the gain by 6dB, taking into account both detection accuracy and engineering practicality, and effectively ensuring the high probability detection of internal defects in the 1002 weld of the heat sink 1001.

[0069] In some embodiments, determining defects by the change in the echo or bottom wave signal of the artificial reflector at a depth twice the thickness of the heat sink 1001 includes: If the amplitude of the echo from the artificial reflector at a depth twice the thickness of the heat sink 1001 is lower than the corresponding height according to the distance-amplitude curve, then weld 1002 is determined to have a defect; or, If the amplitude of the bottom wave signal at a depth twice the thickness of the heat sink 1001 is less than 40% of the full scale of the display screen, or if the bottom wave signal disappears completely, then the weld 1002 is determined to have an unqualified defect.

[0070] In actual testing, the ultrasonic waves need to penetrate the entire cross-section of weld 1002 and reflect at the bottom surface, forming a bottom echo at a depth of twice the thickness of heat sink 1001 (2T). This 2T bottom echo represents the path of the ultrasonic waves that have successfully passed through the double-layer weld and returned, and is an indicator of the internal quality of weld 1002. Once this path is blocked due to defects such as lack of fusion, the bottom echo signal will be significantly attenuated or even disappear completely.

[0071] If a standard comparison test block made of carbon steel is used, and a distance-amplitude curve covering a depth of at least 2T has been prepared, and the detection sensitivity has been set to be 6dB higher than the baseline as described above, then during testing, the presence of the expected artificial reflector echo at a depth of 2T should be observed in real time on the 200-degree ultrasonic testing instrument screen. If the measured echo amplitude is lower than the baseline height corresponding to the depth on the distance-amplitude curve, it indicates that there is a defect at that location sufficient to obstruct sound wave propagation, and the test should be deemed unqualified.

[0072] If on-site calibration is used, that is, in the known qualified area of ​​the weld 1002 under inspection, the bottom echo amplitude at 2T is adjusted to 80% of the full scale of the display screen, and then increased by 6dB as the final detection sensitivity, then the bottom echo at a depth of 2T needs to be continuously monitored during subsequent scans. Once the bottom echo amplitude is found to drop below 40% of the full scale (i.e., below half of the reference value of 80%), or the bottom echo signal disappears completely and there is no visible echo, it can be determined that there is a serious internal defect affecting the propagation of sound waves at that location, and the quality of weld 1002 is unqualified.

[0073] The above criteria, with the integrity of the echo at 2T as the core, combined with the set sensitivity and clear threshold standards, achieves high sensitivity and high reliability in identifying internal defects in weld 1002 of heat sink 1001, and is suitable for various application scenarios such as standardized testing and rapid on-site evaluation.

[0074] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An ultrasonic testing device for heat sink welds, characterized in that, include: The main framework; The connecting mechanism and the elastic mechanism are provided. The connecting mechanism is connected to the frame body through the elastic mechanism, and the connecting mechanism can reciprocate along a first direction through the elastic mechanism. An ultrasonic testing wheel is used to inspect the weld seams of a heat sink component. The ultrasonic testing wheel is rotatably connected to the connecting mechanism so that the ultrasonic testing wheel can rotate about the connecting mechanism as a central axis. An auxiliary wheel is provided, which is arranged opposite to the ultrasonic testing wheel along the first direction and is rotatably connected to the frame body. The ultrasonic testing wheel and the auxiliary wheel can be symmetrically arranged on both sides of the thickness direction of the heat sink weldment and roll synchronously along the surface of the heat sink weldment. Under the action of the elastic mechanism, the first distance between the first outer peripheral surface of the ultrasonic testing wheel and the second outer peripheral surface of the auxiliary wheel can be adjusted according to the thickness of the heat sink weldment, and in the initial state, the first distance is not greater than the thickness of the heat sink weldment.

2. The ultrasonic testing device for heat sink welds according to claim 1, characterized in that, The second outer peripheral surface of the auxiliary wheel is provided with a magnetic layer or an adhesive layer, and the auxiliary wheel can generate adhesion when it is in contact with the surface of the heat sink weldment.

3. The ultrasonic testing device for heat sink welds according to claim 1, characterized in that, The elastic mechanism includes a pair of elastic elements and a guide structure, the guide structure is arranged along the first direction, and the pair of elastic elements are arranged opposite to each other on both sides of the guide structure; The connecting mechanism is a columnar structure arranged along the second direction. The ultrasonic detection wheel is sleeved on the outer periphery of the connecting mechanism. A pair of elastic members are symmetrically arranged on both sides of the ultrasonic detection wheel along the length direction of the connecting mechanism. The connecting mechanism and the guide structure are slidably connected along the first direction. The first direction and the second direction are set perpendicularly.

4. The ultrasonic testing device for heat sink welds according to claim 1, characterized in that, The ultrasonic testing wheel includes a wheel body, a piezoelectric crystal, and a signal transmission device. The wheel body is rotatably connected to the connecting mechanism. The piezoelectric crystal is arranged around the circumference of the wheel body, and the side of the piezoelectric crystal facing away from the wheel body forms the first outer peripheral surface. The piezoelectric wafer and the signal transmission device are electrically connected so that the piezoelectric wafer can receive or send detection signals to the ultrasonic detector through the signal transmission device.

5. The ultrasonic testing device for heat sink welds according to claim 4, characterized in that, The ultrasonic testing wheel also includes a damping block and a protective membrane. The wheel body is a shell structure, and the shell structure and the connecting mechanism form a cavity. The damping block is disposed in the cavity and fixedly connected to the wheel body. The protective film surrounds and covers the first outer peripheral surface of the piezoelectric wafer, which is sandwiched between the damping block and the protective film.

6. The ultrasonic testing device for heat sink welds according to claim 5, characterized in that, The signal transmission device includes: A rotating component is disposed within the cavity and fixedly connected to the wheel body; the rotating component is sleeved on the outer periphery of the connecting mechanism. A conductive slip ring is disposed on the side wall of the connecting mechanism. The rotating member has an annular groove on its surface facing the connecting mechanism. The conductive slip ring has an arc-shaped protrusion facing the cavity. The rotating member covers the conductive slip ring and is connected to it through the annular groove and the arc-shaped protrusion, so that the rotating member can rotate relative to the conductive slip ring. A first wire is located inside the cavity. The rotating member has a wire-passing channel extending through it radially. The wire-passing channel is connected to the annular groove. One end of the first wire is connected to the piezoelectric wafer, and the other end passes through the wire-passing channel and is slidably connected to the arc-shaped protrusion. The second wire has a hollow tubular structure as the connecting mechanism. The conductive slip ring passes through the side wall of the connecting mechanism. One end of the connecting mechanism along its length has an outlet. One end of the second wire extends into the interior of the connecting mechanism and is connected to the conductive slip ring. The other end extends out of the connecting mechanism through the outlet and is used for communication connection with the ultrasonic detector.

7. The ultrasonic testing device for heat sink welds according to claim 1, characterized in that, Also includes: The frame body has an installation space, the ultrasonic testing wheel and the auxiliary wheel are disposed in the installation space, and the handle is disposed on the side of the frame body facing away from the installation space.

8. A testing method, employing the ultrasonic testing device for heat sink welds according to any one of claims 1-7, characterized in that, include: Connect the ultrasonic testing device for the heat sink weld to the ultrasonic testing instrument, set the scanning ratio of the ultrasonic testing instrument to 1:1, and the detection sound path range covers at least twice the thickness of the heat sink. The detection sensitivity is set by using the echo or bottom wave of an artificial reflector at a depth of twice the thickness of the heat sink as the reference signal. The ultrasonic testing device for the heat sink weld is placed on the heat sink weld, the ultrasonic testing wheel is aligned with the width of the weld of the heat sink weld, and the ultrasonic testing wheel is in contact with the surface of the heat sink weld. The ultrasonic testing device for the heat sink weld is pushed to roll along the length of the weld of the heat sink weld. Defects are determined by the change in the echo or bottom wave signal of the artificial reflector at a depth of twice the thickness of the heat sink. If the amplitude of the echo or bottom wave signal of the artificial reflector is reduced or disappears compared with the reference signal, the weld is determined to have an unqualified defect.

9. The detection method according to claim 8, characterized in that, The set detection sensitivity includes: On a carbon steel control block, an artificial reflector with a depth at least twice the thickness of the heat sink was selected, and a distance-amplitude curve was fabricated, with an improvement of 6 dB; or, The ultrasonic testing device for the heat sink weld is set in the qualified area of ​​the weld seam of the heat sink weld, and the ultrasonic testing wheel is aligned with the width of the weld seam of the heat sink weld. The ultrasonic testing wheel is moved back and forth at least one revolution, and the average amplitude of the bottom wave signal at a depth of 2 times the thickness of the heat sink is adjusted to 80% of the full scale of the ultrasonic testing instrument display, and then increased by 6dB.

10. The detection method according to claim 9, characterized in that, The method of determining defects based on changes in the echo or bottom wave signal of an artificial reflector at a depth twice the thickness of the heat sink includes: If the amplitude of the echo from the artificial reflector at a depth twice the thickness of the heat sink is lower than the corresponding height according to the distance-amplitude curve, then the weld is determined to have a defect; or, If the amplitude of the bottom wave signal at a depth of twice the thickness of the heat sink is less than 40% of the full scale of the display screen, or if the bottom wave signal disappears completely, then the weld is determined to have a defect.

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