On-line rapid nondestructive detection device for spot welding quality of metal film and detection method thereof

Abstract

The invention relates to the technical field of nondestructive testing, and discloses an online rapid nondestructive testing device and method for spot welding quality of a metal film, and the online rapid nondestructive testing device comprises an infrared high-speed imaging module, an eddy current heating and measuring module, a synchronous control module and a motion compensation module. A micro-distance optical focusing lens is matched with a high-speed infrared camera, and a thermal imaging sequence of a welding spot area is collected at a preset frame frequency. The eddy current module adopts a composite multi-frequency PCB coil assembly, a heating coil layer and a measuring coil layer are integrated, the heating coil layer covers multiple rows of welding spots to achieve area heating, the measuring coil layer corresponds to the welding spots one to one, and dynamic power adjustment is achieved through a heating power controller. The synchronous control module coordinates the sequential relation of eddy current excitation, detection and infrared imaging, the motion compensation module corrects welding spot position deviation in real time through visual positioning, and the optical focusing precision is ensured. According to the invention, through synchronous acquisition and analysis of multi-modal data, rapid nondestructive detection of welding defects is realized, and the detection precision and the detection efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and in particular to an online rapid nondestructive testing device and method for the quality of metal thin film spot welding. Background Technology

[0002] In modern industry, multilayer metal thin films are widely used in electronic components, high-energy battery electrodes, and aerospace due to their excellent conductivity, lightweight, and corrosion resistance. Taking a certain type of high-energy battery as an example, its electrodes use double-layer aluminum films as conductive materials, and the layers are spot-welded together using a micro-ultrasonic welding process to improve conductivity. The diameter of the weld points is typically within a tiny range of 0.1mm-0.3mm. During automated production, defects such as incomplete or missing welds may occur, affecting product reliability.

[0003] Current methods primarily rely on destructive testing, such as tensile testing or needle-pick methods, which are ineffective at detecting weld defects like incomplete welds and over-welds. To ensure high-speed online non-destructive testing, eddy current methods or optical methods are employed. However, eddy current sensors are typically large in diameter, and vibrations and weld point misalignments on production lines render these methods unreliable. Conventional optical methods, on the other hand, cannot penetrate thin metal films and struggle to effectively monitor the quality of minute weld points, thus failing to meet practical production needs. Therefore, it is necessary to develop non-destructive testing methods that can effectively detect defects. Summary of the Invention

[0004] To address the above problems, this invention provides an online rapid non-destructive testing device for the quality of metal thin film spot welding, which is implemented as follows: An online rapid non-destructive testing device for spot welding quality of metal thin films is used to detect the quality of ultrasonic spot welding of battery electrode tabs. It includes an infrared high-speed imaging module 10, an eddy current heating and measurement module 20, a synchronization control module 30, and a motion compensation module 40, wherein: The infrared high-speed imaging module 10 includes: Infrared high-speed camera 101 is configured to acquire infrared thermal imaging sequences of the solder joint area at a predetermined frame rate; The macro optical focusing lens 102 is configured to focus the infrared radiation of the solder joint area onto the infrared high-speed camera 101, and the macro optical focusing lens 102 has an optimal working distance range. The eddy current heating and detection module 20 includes: The composite multi-frequency eddy current coil assembly 201 adopts a multi-layer PCB structure, including a heating coil layer 2011 and a measuring coil layer 2012; The heating coil layer 2011 is configured to cover a multi-row solder joint array area to generate induction eddy current heating of the metal thin film. The measuring coil layer 2012 is configured to consist of an array of multiple micro coils 2012-1, and the distribution position of the micro coils 2012-1 and the size of their effective sensing area correspond one-to-one with the solder joints in the area to be measured. A heating power controller 202 is connected to the heating coil layer 2011 and the measuring coil layer 2012, and is configured to dynamically adjust the excitation power applied to the heating coil layer 2011 based on the measuring signal obtained by the measuring coil layer 2012; The synchronization control module 30 is configured to coordinate and control the excitation timing and signal acquisition timing of the eddy current heating and detection module 20 and the image acquisition timing of the infrared high-speed imaging module 10. The motion compensation module 40 employs a visual positioning device, configured to acquire solder joint position offset information and adjust the optical focusing area of ​​the macro optical focusing lens 102 in real time based on this information.

[0005] Furthermore, an insulating layer 2013 is provided between the heating coil layer 2011 and the measuring coil layer 2012, and the insulating layer 2013 has thermal conductivity and electrical insulation properties; And / or, the composite multi-frequency eddy current coil assembly 201 further includes an electromagnetic shielding layer 2014.

[0006] This invention also discloses an online rapid non-destructive testing method for the quality of metal thin film spot welding, employing the testing device described in any one of the above methods, and comprising the following steps: S1. Installation of detection device The infrared high-speed imaging module 10 is non-contactly positioned above the metal film to be tested, and the composite multi-frequency eddy current coil assembly 201 is non-contactly positioned below the metal film to be tested, with the field of view of the infrared high-speed imaging module 10 aligned vertically with the measurement area of ​​the composite multi-frequency eddy current coil assembly 201. S2. Conduct testing S21. Measurement of lift-off gap and initial interlayer gap: Time-division multi-frequency measurement is performed using the measurement coil layer 2012: A first excitation frequency (f1) is applied to the measurement coil layer 2012, and the high-frequency impedance phase signal of the corresponding region of each micro coil is measured. Based on the high-frequency impedance phase signal, the lift-off gap between the composite multi-frequency eddy current coil assembly 201 and the metal film surface is determined. A second excitation frequency (f2) is applied to the measurement coil layer 2012, the second excitation frequency (f2) being lower than the first excitation frequency (f1), and the low-frequency impedance amplitude signal of the corresponding region of each micro coil is measured. The interlayer gap of the metal film before heating is determined based on the low-frequency impedance amplitude signal. S22. Simultaneous heating, thermal imaging, and measurement of interlayer gap after heating: The synchronization control module 30 starts the infrared high-speed camera 101 to begin image acquisition preparation; The heating power controller 202 calculates and applies dynamically adjusted excitation power to the heating coil layer 2011 based on the lift-off gap measured in step S21, thereby performing pulsed eddy current heating on the metal film. While or immediately after the heating coil layer 2011 is working, the infrared high-speed camera 101 acquires infrared thermal imaging sequences of the solder joint area under the control of the synchronization control module 30. During the operation of the heating coil layer 2011 or within a predetermined time after heating stops, the second excitation frequency (f2) is applied again to the measurement coil layer 2012 to measure the low-frequency impedance amplitude signal of the corresponding region of each micro coil, and the interlayer gap of the heated metal film is determined based on the low-frequency impedance amplitude signal measured this time. S3. Weld joint quality assessment The quality of a solder joint is determined based on at least one of the following information: S31. Analyze the infrared thermal imaging sequence acquired in step S22, and determine the connection status of the solder joints based on the temperature distribution, temperature rise amplitude, or cooling rate characteristics of each solder joint area during the heating and cooling process. S32. Compare the interlayer gap before heating and the interlayer gap after heating of the same solder joint area obtained in steps S21 and S22, and determine the solder joint connection status based on the amount or pattern of the gap change.

[0007] Compared with the prior art, the present invention has the following beneficial effects: I. This invention uses an infrared high-speed camera in conjunction with a macro optical focusing lens, which can accurately capture the infrared thermal radiation distribution of tiny solder joint areas with high spatiotemporal resolution. By analyzing the heat conduction characteristics, the solder joint connection quality can be accurately determined, realizing non-destructive testing and quality assessment of tiny solder joints.

[0008] Second, an innovative top-to-bottom collaborative detection architecture is adopted, integrating the eddy current heating and detection modules under the metal thin film to be tested. Through the synchronous control module, the timing of eddy current excitation, signal acquisition and infrared thermal imaging are precisely coordinated, realizing the spatiotemporal synchronous acquisition of multi-physics field data, which significantly improves the detection accuracy and reliability.

[0009] Third, this device adopts a dynamic compensation mechanism that combines optical vision positioning and eddy current detection. It not only adapts to position fluctuations on the production line, but also achieves closed-loop control of excitation energy through the dual functions of the eddy current module (gap measurement and thin film heating), ensuring the stability of heating power under different working conditions and providing a reliable guarantee for ultrasonic weld point quality inspection on high-speed production lines. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the present invention or the prior art, or to provide a simple description of the drawings used in the prior art, it is obvious that those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0011] Figure 1 This is a schematic diagram of the detection device of the present invention.

[0012] Figure 2 This is a schematic diagram of the infrared high-speed imaging module.

[0013] Figure 3 This is a schematic diagram of the eddy current heating and measurement module.

[0014] Figure 4 This is a schematic diagram of a composite multi-frequency eddy current coil assembly.

[0015] Figure 5 This is a schematic diagram of the heating coil and the measuring coil layer.

[0016] Figure 6 This is a schematic diagram of the components of the detection device of the present invention.

[0017] Figure 7 This is a schematic diagram of the testing process.

[0018] Figure 8 This is a schematic diagram of the control flow for the synchronous control module, eddy current heating and measurement module.

[0019] In the picture: 10 - Infrared high-speed imaging module, 101 - Infrared high-speed camera, 102 - Macro optical focusing lens; 20-Eddy current heating and measurement module, 201-Composite multi-frequency eddy current coil assembly, 2011-Heating coil layer, 2012-Measurement coil layer, 2012-1-Miniature coil, 2013-Insulation layer, 2014-Electromagnetic shielding layer, 202-Heating power controller; 30 - Synchronous control module; 40 - Motion compensation module; 50 - Metal thin film to be tested. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0021] In the description of this invention, 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 indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0022] This embodiment focuses on the inspection of ultrasonic welding quality of battery electrode tabs, implemented on a high-speed continuous production line. Since the production line welding cycle is ≥20 points / second, the corresponding single-point quality inspection needs to be completed within 50ms / point. Furthermore, the weld point spacing is small, requiring a miniaturized inspection probe design. Additionally, due to the flexible and easily deformable nature of the tab material, a non-contact inspection method is necessary to avoid potential material damage from contact inspection.

[0023] Based on the above-mentioned testing conditions, and considering high-speed testing requirements, spatial constraints, and material properties, this invention discloses an online rapid non-destructive testing device for the quality of metal thin film spot welding, comprising an infrared high-speed imaging module 10, an eddy current heating and measurement module 20, a synchronous control module 30, and a motion compensation module 40, wherein: The infrared high-speed imaging module 10 includes an infrared high-speed camera 101 and a macro optical focusing lens 102.

[0024] The infrared high-speed camera 101 is configured to acquire infrared thermal imaging sequences of the solder joint area at a predetermined frame rate. The frame rate of the infrared high-speed camera 101 can be flexibly set according to actual detection needs. It can acquire infrared thermal imaging sequences of the solder joint area at extremely high speed, ensuring that the temperature changes of the solder joint during the heating and cooling stages can be completely recorded even when the metal film moves rapidly.

[0025] The macro optical focusing lens 102 is configured to focus the infrared radiation from the solder joint area onto the infrared high-speed camera 101. The macro optical focusing lens 102 has an optimal working distance range. That is, the macro optical focusing lens 102 adopts a unique optical design that can efficiently and accurately focus the infrared radiation emitted from the solder joint area onto the photosensitive element of the infrared high-speed camera 101, so that the acquired thermal imaging image is clear and has high resolution, and can clearly show the subtle temperature differences of the solder joint.

[0026] The eddy current heating and detection module 20 includes a composite multi-frequency eddy current coil assembly 201 and a heating power controller 202.

[0027] The composite multi-frequency eddy current coil assembly 201 adopts a multi-layer PCB structure, including a heating coil layer 2011 and a measuring coil layer 2012; an insulating layer 2013 is provided between the heating coil layer 2011 and the measuring coil layer 2012, and the insulating layer 2013 has thermal conductivity and electrical insulation properties. The composite multi-frequency eddy current coil assembly 201 also includes an electromagnetic shielding layer 2014. The insulating layer 2013 effectively isolates the heating coil layer 2011 and the measuring coil layer 2012 while rapidly conducting heat, ensuring efficient heat transfer to the metal film. The electromagnetic shielding layer 2014 is generally made of copper foil or ferrite material, which can effectively shield external electromagnetic interference and prevent its own generated electromagnetic field from affecting surrounding equipment, ensuring the accuracy and stability of the detection signal. The heating power controller 202 is connected to the heating coil layer 2011 and the measuring coil layer 2012, and is configured to dynamically adjust the excitation power applied to the heating coil layer 2011 based on the measurement signal obtained by the measuring coil layer 2012. Furthermore, the heating power controller 202 has an advanced built-in control algorithm, which can adjust the excitation power applied to the heating coil layer 2011 in real time and dynamically according to the measurement signal fed back by the measuring coil layer 2012, so as to ensure that each heating process is stable and controllable.

[0028] Furthermore, in this embodiment, the heating coil layer 2011 is configured to cover a multi-row solder joint array area to generate induced eddy currents to heat the metal thin film; that is, when an alternating current is applied, induced eddy currents can be generated in the metal thin film, and the eddy current heating effect can be used to achieve rapid heating of the metal thin film.

[0029] The measuring coil layer 2012 is configured to consist of an array of multiple micro coils 2012-1. The distribution position of the micro coils 2012-1 and the size of their effective sensing area correspond one-to-one with the solder joints in the area to be measured, which can accurately measure the changes in electromagnetic parameters of the corresponding solder joint area. The synchronization control module 30 is configured to coordinate and control the excitation timing and signal acquisition timing of the eddy current heating and detection module 20 and the image acquisition timing of the infrared high-speed imaging module 10. The synchronization control module 30 ensures the time consistency of multimodal detection data and realizes equipment collaborative control with microsecond-level precision. It includes a complete closed-loop process of command issuance, excitation triggering, data acquisition and status feedback.

[0030] The specific implementation may include the following steps: the host computer sends a set of instructions containing detection parameters to the synchronization control module; the synchronization control module starts the eddy current excitation module through a hardware trigger signal; the FPGA counter built into the synchronization control module performs precise delay control; after the preset delay arrives, the synchronization controller executes the following in sequence: terminate the eddy current excitation signal; start the analog-to-digital converter (ADC) to sample the eddy current signal; trigger the infrared camera to take pictures through the optical synchronization interface; receive the completion status signals returned by each module; and feed back the synchronization completion status with a timestamp to the host computer.

[0031] The motion compensation module 40 employs a visual positioning device, such as an industrial camera paired with a dedicated image processing algorithm, to acquire solder joint position offset information and adjust the optical focusing area of ​​the macro optical focusing lens 102 in real time based on this information. Once a solder joint position offset is detected, the offset amount can be calculated within a very short time (usually less than 10 ms), and this information is fed back to the drive mechanism of the macro optical focusing lens 102. The drive mechanism adjusts the position and angle of the lens in real time according to the instructions, ensuring that the optical focusing area is always accurately aligned with the solder joint, effectively compensating for the effects of production line vibration and solder joint position offset.

[0032] Furthermore, this invention also discloses an online rapid non-destructive testing method for the quality of metal thin film spot welding, employing the aforementioned testing device, and comprising the following steps: S1. Installation of detection device The infrared high-speed imaging module 10 is non-contactly positioned above the metal film to be tested, and the infrared high-speed camera 101 and the macro optical focusing lens 102 are coordinated to ensure that the lens is within the optimal working distance range. The lens optical axis is then calibrated using a level to ensure that it is perpendicular to the surface of the metal film. The composite multi-frequency eddy current coil assembly 201 is non-contactly positioned below the metal film to be tested, and its position is precisely adjusted using a laser alignment device to ensure that the field of view of the infrared high-speed imaging module 10 is aligned vertically with the measurement area of ​​the composite multi-frequency eddy current coil assembly 201. S2. Conduct testing S21. Measurement of lift-off gap and initial interlayer gap: Time-division multi-frequency measurement is performed using the measurement coil layer 2012: A first excitation frequency (f1) is applied to the measurement coil layer 2012, and the high-frequency impedance phase signal of the corresponding region of each micro coil is measured. Based on the high-frequency impedance phase signal, the lift-off gap between the composite multi-frequency eddy current coil assembly 201 and the metal film surface is determined. A second excitation frequency (f2) is applied to the measurement coil layer 2012, the second excitation frequency (f2) being lower than the first excitation frequency (f1), and the low-frequency impedance amplitude signal of the corresponding region of each micro coil is measured. The interlayer gap of the metal film before heating is determined based on the low-frequency impedance amplitude signal. S22. Simultaneous heating, thermal imaging, and measurement of interlayer gap after heating: The synchronization control module 30 starts the infrared high-speed camera 101 to begin image acquisition preparation; The heating power controller 202 calculates and applies dynamically adjusted excitation power to the heating coil layer 2011 based on the lift-off gap measured in step S21, thereby performing pulsed eddy current heating on the metal film. While or immediately after the heating coil layer 2011 is working, the infrared high-speed camera 101 acquires infrared thermal imaging sequences of the solder joint area under the control of the synchronization control module 30. During the operation of the heating coil layer 2011 or within a predetermined time after heating stops, the second excitation frequency (f2) is applied again to the measurement coil layer 2012 to measure the low-frequency impedance amplitude signal of the corresponding region of each micro coil, and the interlayer gap of the heated metal film is determined based on the low-frequency impedance amplitude signal measured this time. Since the optical method allows for a certain deviation on the production line, and the eddy current excitation and detection module can be used for both gap measurement and heating of the aluminum film, the power of each excitation heating to the metal film can be kept basically stable, thus ensuring the quality of the online high-speed non-destructive testing ultrasonic microwave spot welding process.

[0033] S3. Weld joint quality assessment The quality of a solder joint is determined based on at least one of the following information: S31. Analyze the infrared thermal imaging sequence acquired in step S22, and determine the connection status of the solder joints based on the temperature distribution, temperature rise amplitude, or cooling rate characteristics of each solder joint area during the heating and cooling process. S32. Compare the interlayer gap before heating and the interlayer gap after heating of the same solder joint area obtained in steps S21 and S22, and determine the solder joint connection status based on the amount or pattern of the gap change.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. An online rapid non-destructive testing device for the spot welding quality of metal thin film, used for testing the spot welding quality of ultrasonic welding of battery electrode tabs, characterized in that, It includes an infrared high-speed imaging module (10), an eddy current heating and measurement module (20), a synchronization control module (30), and a motion compensation module (40), wherein: The infrared high-speed imaging module (10) includes: An infrared high-speed camera (101) is configured to acquire an infrared thermal imaging sequence of the solder joint area at a predetermined frame rate; A macro optical focusing lens (102) is configured to focus the infrared radiation of the solder joint area onto the infrared high-speed camera (101), and the macro optical focusing lens (102) has an optimal working distance range; The eddy current heating and detection module (20) includes: The composite multi-frequency eddy current coil assembly (201) adopts a multi-layer PCB structure, including a heating coil layer (2011) and a measuring coil layer (2012). The heating coil layer (2011) is configured to cover a multi-row solder joint array area to generate induction eddy current heating of the metal thin film; The measuring coil layer (2012) is configured to consist of an array of multiple micro coils (2012-1), and the distribution position of the micro coils (2012-1) and the size of their effective sensing area correspond one-to-one with the solder joints in the area to be measured. A heating power controller (202), connected to the heating coil layer (2011) and the measuring coil layer (2012), is configured to dynamically adjust the excitation power applied to the heating coil layer (2011) based on the measurement signal obtained by the measuring coil layer (2012); The synchronization control module (30) is configured to coordinate and control the excitation timing and signal acquisition timing of the eddy current heating and detection module (20) and the image acquisition timing of the infrared high-speed imaging module (10); The motion compensation module (40) uses a visual positioning device and is configured to acquire solder joint position offset information and adjust the optical focusing area of ​​the macro optical focusing lens (102) in real time based on the information.

2. The detection device according to claim 1, characterized in that, An insulating layer (2013) is provided between the heating coil layer (2011) and the measuring coil layer (2012), the insulating layer (2013) having thermal conductivity and electrical insulation properties; and / or, The composite multi-frequency eddy current coil assembly (201) also includes an electromagnetic shielding layer (2014).

3. An online rapid non-destructive testing method for the quality of metal thin film spot welding, employing the testing device described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Installation of detection device The infrared high-speed imaging module (10) is non-contactly positioned above the metal film to be tested, and the composite multi-frequency eddy current coil assembly (201) is non-contactly positioned below the metal film to be tested, with the field of view of the infrared high-speed imaging module (10) aligned vertically with the measurement area of ​​the composite multi-frequency eddy current coil assembly (201). S2. Conduct testing S21. Measurement of lift-off gap and initial interlayer gap: Time-division multi-frequency measurement was performed using the aforementioned measurement coil layer (2012): A first excitation frequency (f1) is applied to the measurement coil layer (2012), and the high-frequency impedance phase signal of the corresponding region of each micro coil is measured. Based on the high-frequency impedance phase signal, the lift-off gap between the composite multi-frequency eddy current coil assembly (201) and the metal film surface is determined. A second excitation frequency (f2) is applied to the measurement coil layer (2012), the second excitation frequency (f2) being lower than the first excitation frequency (f1), and the low-frequency impedance amplitude signal of the corresponding region of each micro coil is measured. The interlayer gap of the metal thin film before heating is determined based on the low-frequency impedance amplitude signal. S22. Simultaneous heating, thermal imaging, and measurement of interlayer gap after heating: The synchronization control module (30) starts the infrared high-speed camera (101) to begin image acquisition preparation; The heating power controller (202) calculates and applies dynamically adjusted excitation power to the heating coil layer (2011) based on the lift-off gap measured in step S21, thereby performing pulsed eddy current heating on the metal film. While the heating coil layer (2011) is working, or immediately afterward, the infrared high-speed camera (101) acquires infrared thermal imaging sequences of the solder joint area under the control of the synchronization control module (30). During the operation of the heating coil layer (2011) or within a predetermined time after heating stops, the second excitation frequency (f2) is applied again to the measurement coil layer (2012) to measure the low-frequency impedance amplitude signal of the corresponding area of ​​each micro coil, and the interlayer gap of the heated metal film is determined based on the low-frequency impedance amplitude signal measured this time. S3. Weld joint quality assessment The quality of a solder joint is determined based on at least one of the following information: S31. Analyze the infrared thermal imaging sequence acquired in step S22, and determine the connection status of the solder joints based on the temperature distribution, temperature rise amplitude, or cooling rate characteristics of each solder joint area during the heating and cooling process. S32. Compare the interlayer gap before heating and the interlayer gap after heating of the same solder joint area obtained in steps S21 and S22, and determine the solder joint connection status based on the amount or pattern of the gap change.

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