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

Abstract

The invention provides an on-line rapid nondestructive detection device and method for spot welding quality of a metal film, which are particularly suitable for ultrasonic welding spot detection of a battery electrode plate tab. The device comprises a feeding module, a detection module, a discharging module and a control module. The feeding module achieves accurate positioning of electrode slices through a three-dimensional measurement video head and an adjustable guide rail. The detection module adopts a roller type probe detection sensor to perform resistance detection on a welding spot in a step-by-step manner, so that high-precision measurement is ensured; and the discharging module automatically sorts qualified and unqualified products based on the detection result. The detection method comprises the steps of electrode plate feeding and positioning, adsorption and in-place detection, roller type potential detection and quality judgment and sorting, and rapid quality evaluation is achieved through resistance waveform comparison. The scheme has remarkable advantages, high-efficiency and high-accuracy detection is realized through accurate positioning, high-precision detection and automatic sorting, the labor cost is reduced, the production quality and efficiency are remarkably improved, and powerful support is provided for enterprise production layout optimization.

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 industrial sectors such as automobiles, high-speed rail, and batteries, spot welding between metal sheets is an indispensable key technology. Currently, various spot welding methods exist, including laser welding, capacitive discharge welding, friction stirring, magnetic pulse welding, electron beam welding, micro-arc oxidation, hot pressing, and ultrasonic welding. However, these welding methods inevitably suffer from some problems, such as incomplete welds and lack of penetration. This is especially true for spot welding of thin-film metal materials, such as in-line ultrasonic spot welding between aluminum alloy films on battery electrode plates, where incomplete welds and lack of penetration are more prominent, severely impacting product quality and performance. Because these weld points are so small, current industrial practice primarily relies on destructive testing, such as the "needle-picking method," which uses mechanical peeling to assess weld strength. However, this method is inefficient, damages the product, and cannot quantify defects. Traditional non-destructive testing (NDT) methods have limitations due to the tiny size and dense density of solder joints, and the generally small weld nuggets. For example, ultrasonic testing requires a coupling agent, and sound waves attenuate rapidly and have a low signal-to-noise ratio in thin films; eddy current testing probes are currently difficult to scale to such small structures, resulting in insufficient spatial resolution; optical testing methods such as infrared thermography are susceptible to surface reflection interference, and the small heat capacity and rapid heat diffusion of thin films lead to weak temperature difference signals and poor detection results. Therefore, the problem of thin film solder joint detection remains unsolved.

[0003] In summary, the industry currently lacks rapid, high-precision, non-destructive testing methods suitable for metal thin film weld joints. There is an urgent need to break through key technologies such as micro-defect sensing and weak signal extraction to meet the quality control requirements of metal thin film spot welding in high-reliability fields such as new energy batteries. Summary of the Invention

[0004] To address the above problems, this invention provides an online rapid non-destructive testing device and method for the quality of metal thin film spot welding. This invention is implemented as follows: An online rapid non-destructive testing device for spot welding quality of metal thin films is used to test the quality of ultrasonic spot welding of battery electrode tabs. The device includes a feeding module (10), a testing module (20), an unloading module (30), and a control module (40), wherein: The feeding module (10) is used to transport the electrode sheet (100) that has been welded with the tab (1001) to the testing table (201), and includes a feeding conveyor belt (101) and a positioning guide mechanism (102). The positioning and guiding mechanism (102) includes a three-dimensional measurement video head (1021) and an adjustable guide rail (1022). The three-dimensional measurement video head (1021) is installed above the feeding conveyor belt (101) and is used to measure and obtain the size information of the electrode sheet (100); The adjustable guide rail (1022) is used to guide the electrode sheet (100) onto the detection stage (201); The detection module (20) includes a detection stage (201), a detection robot (202), and a roller probe detection sensor (203) installed at the end of the detection robot (202). The testing station (201) is provided with a testing station (2011). Below the testing station (2011) is a pneumatic adsorption device (2012) for adsorbing the electrode sheet (100) to make it flat, and a sensing sensor for detecting whether the electrode sheet (100) is placed in place and generating a positioning signal. The roller-type probe detection sensor (203) includes a roller base (2031), a circuit module, a graded rolling mechanism (2033), and a clamping probe (2034). The roller base (2031) is cylindrical, and multiple rows of probe groups (2035) are evenly distributed along the circumference of the surface. Each row of probe groups (2035) contains multiple probe contacts arranged at equal intervals along the axial direction. The spacing between each probe contact matches the solder joints (1002) distributed on the electrode sheet (100), so that the probe contacts correspond one-to-one with the solder joints (1002). The circuit module is integrated inside the roller base (2031) and is used to apply a constant current to adjacent solder joints, measure the voltage drop, and calculate the output resistance value. The segmented rolling mechanism (2033) drives the rolling base (2031) to rotate in a segmented step manner, and the rotation angle of each segment corresponds to the spacing of the two rows of probe groups (2035). The clamping probe (2034) is fixedly installed on the detection robot (202); The unloading module (30) is used to sort qualified and unqualified electrode sheets (100) according to the test results, including a sorting robot (301), a qualified channel (302) and an unqualified channel (303). The control module (40) is electrically connected to the feeding module (10), the detection module (20), and the unloading module (30). The control module (40) is configured as follows: The electrode sheet (100) size measurement information obtained by the three-dimensional measurement video head (1021) is received, and the width of the adjustable guide rail (1022) is controlled to adapt to electrode sheets (100) of different sizes and widths. The signal from the sensing sensor is collected, and the roller probe detection sensor (203) on the detection robot (202) is controlled to perform light-touch rolling potential detection on the spot welding area of ​​the electrode sheet (100); Trigger the sorting action of the sorting robot (301).

[0005] An online rapid non-destructive testing method for the quality of metal thin film spot welding, employing the testing device described above, includes the following steps: S1. Electrode loading and positioning The electrode sheet (100) with the tab (1001) welded is conveyed by the feeding conveyor belt (101). The size information of the electrode sheet (100) is measured by the three-dimensional measurement video head (1021). Based on the size information, the width of the adjustable guide rail (1022) is adjusted to fit the width of the electrode sheet (100). The electrode sheet (100) is guided to the inspection station (2011) of the inspection table (201) by the adjustable guide rail. S2. Electrode Adsorption and Placement Detection The pneumatic adsorption device (2012) is activated to adsorb the electrode plate (100) and make it flat. The sensor detects whether the electrode plate (100) is in place, generates a positioning signal and transmits it to the control module (40). S3. Roller-type potential detection After receiving the positioning signal, the control module (40) drives the detection robot (202) to move the roller probe detection sensor (203) to the spot welding area of ​​the electrode sheet (100). After completing the resistance detection of each two rows of probe groups (2035), the roller base (2031) rotates at a fixed angle to align the next two rows of probe groups (2035) with the adjacent weld points until the entire weld point area is covered. The circuit module calculates and outputs the resistance value between adjacent weld points in real time. S4. Quality Judgment and Sorting The control module (40) compares the waveform of the resistance value of each weld point with the standard waveform to determine whether the welding quality is qualified. The sorting robot (301) is triggered to sort qualified electrode sheets to qualified channel (302) and unqualified electrode sheets to unqualified channel (303), thus completing online rapid sorting.

[0006] Compared with the prior art, the present invention has the following beneficial effects: This invention integrates modules for the entire process of feeding, testing, and unloading. Through coordinated operation of the control module, it achieves fully automated operation from conveying and positioning to testing and sorting, eliminating the need for manual intervention in traditional testing. This significantly improves testing efficiency and is suitable for the high-speed production lines required for battery manufacturing. Furthermore, each functional module can be maintained or upgraded independently, facilitating integration with existing production lines and offering strong engineering application flexibility. Specifically, this invention utilizes an innovative roller-type probe sensor with a stepped design, ensuring a one-to-one correspondence between the probe contacts and solder joints. This allows for rapid coverage of the entire solder joint area, and the use of a 3D measurement video head to acquire electrode sheet size information in real time ensures accurate positioning of electrode sheets of different sizes, significantly shortening the testing time. The invention measures time to meet the needs of rapid online testing; it also incorporates a pneumatic adsorption device to keep the electrode plates flat, further improving testing accuracy; in addition, this invention combines micro-resistance measurement method, applying a constant current to adjacent solder joints through a circuit module and measuring and calculating the resistance value, accurately reflecting the welding quality of the solder joints. This avoids the misjudgment problems caused by signal attenuation, insufficient resolution, or environmental interference in traditional ultrasonic, eddy current, and optical testing, effectively solving the core contradiction of "high precision" and "high efficiency" in metal thin film solder joint testing. Compared with traditional methods, it has significant advantages of being non-destructive, fast, low-cost, and easy to integrate, providing a reliable tool for quality control in fields such as battery manufacturing. Attached Figure Description

[0007] 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.

[0008] Figure 1 This is a flowchart of the detection process of the present invention.

[0009] Figure 2 This is a schematic diagram of the overall structure of the detection device of the present invention.

[0010] Figure 3 This is a schematic diagram of the feeding module of the present invention.

[0011] Figure 4 This is a schematic diagram of the detection module of the present invention.

[0012] Figure 5 This is a schematic diagram of the detection robot of the present invention.

[0013] Figure 6 for Figure 5 An enlarged schematic diagram of region A in the middle.

[0014] Figure 7 This is a schematic diagram of a metal thin film solder joint.

[0015] Figure 8 This is a schematic diagram illustrating the principle of potentiometric detection.

[0016] Figure 9 This is a schematic diagram of potential detection waveforms for different welding conditions.

[0017] Figure 10 This is a schematic diagram of the welding area structure of the electrode sheet. Detailed Implementation

[0018] 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.

[0019] Taking online inspection of the ultrasonic welding quality of battery electrode tabs as an example, the welding principle of ultrasonic welding of battery electrode tabs is to use high-frequency vibration transmitted through the welding head to the tab and electrode stack, generating frictional heat that causes plastic deformation of the interface metal. Typical combinations include using aluminum foil with a thickness of only 0.1~0.3mm welded to an aluminum current collector as the positive electrode tab, and using copper foil with a thickness of only 0.1~0.2mm welded to a nickel or copper current collector as the negative electrode tab. Common welding defects include incomplete welds and over-welding. Example

[0020] This embodiment describes a cycle-based production line structure, in which the welded electrode sheets are transferred to a rapidly constructed online testing line for inspection, specifically including: Reference Attachment Figure 1-10 As shown, an online rapid non-destructive testing device for the quality of metal thin film spot welding includes a feeding module 10, a testing module 20, a discharging module 30, and a control module 40, wherein: The feeding module 10 is used to transport the electrode sheet 100 that has been welded with the tab 1001 to the testing table 201. It includes a feeding conveyor belt 101 and a positioning guide mechanism 102. The feeding conveyor belt can be a single-channel or double-channel conveyor belt. The conveying speed can be adjusted according to the testing efficiency, the spacing between electrode sheets, the size of the electrode sheets, etc. The positioning and guiding mechanism 102 includes a three-dimensional measurement video head 1021 and an adjustable guide rail 1022; The three-dimensional measurement video head 1021 is installed above the feeding conveyor belt 101 and is used to measure and acquire the size information of the electrode sheet 100. The three-dimensional measurement video head 1021 can adopt a high-pixel CMOS sensor to improve the detection accuracy. The adjustable guide rail 1022 is used to guide the electrode sheet 100 onto the detection stage 201; Since the electrode sheets to be tested come in various sizes and specifications, in order to improve the applicability of the testing device, the three-dimensional measurement video head 1021 is used to acquire and determine the current size of the electrode sheet in real time, dynamically adjust the existing guide rail width, and perform alignment and transmission of the electrode sheet to ensure accurate positioning of electrode sheets of different sizes.

[0021] The detection module 20 includes a detection stage 201, a detection robot 202, and a roller-type probe detection sensor 203 installed at the end of the detection robot 202. The testing station 201 is equipped with a testing station 2011. Below the testing station 2011 is a pneumatic adsorption device 2012, used to adsorb the electrode sheet 100 to ensure it is flat, avoiding testing errors caused by wrinkles or warping, and further improving testing accuracy. Specifically, it includes several pneumatic suction cups arranged in a rectangular array below the testing station 2011, each suction cup providing an adjustable negative pressure of 0.5-1.2 bar. The testing station also includes a sensor 2013, used to detect whether the electrode sheet 100 is in place and generate a positioning signal. The roller-type probe detection sensor 203 includes a roller base 2031, a circuit module, a graded rolling mechanism 2033, and a clamping probe 2034. The roller base 2031 is cylindrical, with multiple rows of probe groups 2035 evenly distributed along its circumference. Each row of probe groups 2035 contains multiple probe contacts arranged at equal intervals along the axial direction. The spacing between each probe contact matches the solder joints 1002 distributed on the electrode sheet 100, ensuring a one-to-one correspondence between the probe contacts and solder joints 1002. This achieves precise contact and detection of minute solder joints, overcoming the technical bottlenecks of traditional eddy current testing, which is limited by the difficulty in adapting probe size and insufficient spatial resolution. Furthermore, the roller-type probes eliminate the need for coupling agents or other auxiliary media, avoiding contamination or physical damage to the electrode sheet, thus meeting the requirements of non-destructive testing. The probe material can be beryllium copper alloy plated with gold. Beryllium copper alloy has a conductivity of 20%-28%, and gold plating further improves surface conductivity, ensuring the accuracy of micro-resistance measurement. It also has good elastic recovery, ensuring that the probe contacts do not deform after frequent contact and maintain consistent pressure. The probe array matches the solder joint distribution, ensuring that each solder joint is accurately measured and avoiding missed detections.

[0022] The circuit module, integrated within the roller base 2031, applies a constant current to adjacent solder joints, measures the voltage drop, and calculates the output resistance value. The circuit module employs a constant current source with an accuracy error controlled within ±0.1%, improving detection sensitivity. The resistance value directly reflects the internal quality of the solder joint through an electrical signal, accurately indicating the welding quality (such as incomplete solder joints or insufficient penetration), avoiding misjudgments caused by signal attenuation, insufficient resolution, or environmental interference in traditional ultrasonic, eddy current, and optical inspections.

[0023] Furthermore, an anti-interference circuit was designed, integrating filtering and temperature compensation functions into the circuit module to reduce the impact of environmental noise on microresistance measurement.

[0024] The segmented rolling mechanism 2033 drives the rolling base 2031 to rotate in a segmented step manner, and each rotation angle corresponds to the spacing of the two rows of probe groups 2035, which can quickly cover the entire solder joint area. The segmented rolling step detection ensures accurate positioning of the probe group, avoids sliding errors, significantly shortens the detection time of the electrode sheet, and meets the requirements of online rapid detection. The clamping probe 2034 is fixedly installed on the detection robot arm 202; Through adsorption and automatic sorting, the electrode sheet 100 is quickly positioned and fixed. The detection robot 202 drives the roller probe to scan quickly, meeting the production line cycle time. The control module 40 processes the detection data in real time and drives the sorting robot 301 to classify and place qualified / unqualified products, realizing closed-loop quality control.

[0025] The unloading module 30 is used to sort qualified and unqualified electrode sheets 100 according to the test results. It includes a sorting robot 301, a qualified channel 302, and an unqualified channel 303. The unloading module automatically sorts qualified and unqualified products according to the test results, supporting rapid isolation and traceability of unqualified products, facilitating timely adjustment of welding process parameters on the production line, and reducing the scrap rate. Preferably, the sorting robot 301 can be a multi-degree-of-freedom robotic arm with a simulated gripper, integrating force control sensors to achieve flexible gripping of the electrode sheets 100, avoiding electrode tab deformation. Furthermore, the simulated gripper can be embedded with an intelligent module to dynamically adjust the gripper's clamping width based on the dimensional data obtained from the 3D measurement video head 1021. Additionally, a fine anti-static design is incorporated at the gripper end to prevent electrostatic damage to the battery materials.

[0026] The control module 40 is electrically connected to the feeding module 10, the detection module 20, and the unloading module 30. The control module 40 is configured as follows: The device receives the electrode sheet 100 size measurement information obtained by the three-dimensional measurement video head 1021 and controls the width of the adjustable guide rail 1022 to adapt to electrode sheets 100 of different sizes and widths. Through the dynamic linkage between the three-dimensional measurement video head and the adjustable guide rail, the device of the present invention can adapt to electrode sheets of different widths, which is suitable for the testing needs of various battery products and reduces the equipment investment cost of enterprises. The signal from the sensing sensor is collected, and the roller probe detection sensor 203 on the detection robot 202 is controlled to perform light-touch rolling potential detection on the spot welding area of ​​the electrode sheet 100. Based on this, the real-time detected resistance value waveform is compared with the standard waveform diagram to realize intelligent judgment of welding quality, reduce manual interpretation error, and improve detection consistency. The sorting action of the sorting robot 301 is triggered.

[0027] The device of this invention integrates modules for the entire process of feeding, testing, and unloading. Through the coordinated operation of the control module, it achieves fully automated operation from conveying and positioning to testing and sorting, eliminating the need for manual intervention in traditional testing, thus greatly improving testing efficiency. It is suitable for the needs of high-speed production lines in battery production, and each functional module can be maintained or upgraded independently, making it easy to connect with existing production lines and providing strong flexibility in engineering applications.

[0028] An online rapid non-destructive testing method for the quality of metal thin film spot welding, employing the testing device described above, includes the following steps: S1. Electrode loading and positioning The electrode sheet 100 with the tab 1001 welded is conveyed by the feeding conveyor belt 101. The size information of the electrode sheet 100 is measured by the three-dimensional measurement video head 1021. Based on the size information, the width of the adjustable guide rail 1022 is adjusted to fit the width of the electrode sheet 100. The electrode sheet 100 is guided to the inspection station 2011 of the inspection table 201 by the adjustable guide rail. S2. Electrode Adsorption and Placement Detection The pneumatic adsorption device 2012 is activated to adsorb the electrode plate 100 and make it flat. The sensor detects whether the electrode plate 100 is in place, generates a positioning signal and transmits it to the control module 40. S3. Roller-type potential detection After receiving the positioning signal, the control module 40 drives the detection robot 202 to move the roller probe detection sensor 203 to the spot welding area of ​​the electrode sheet 100. After completing the resistance detection of two rows of probe groups 2035, the roller base 2031 rotates at a fixed angle to align the next two rows of probe groups 2035 with the adjacent weld points until the entire weld point area is covered. The circuit module calculates and outputs the resistance value between adjacent weld points in real time. S4. Quality Judgment and Sorting Control module 40 compares the waveform of the resistance value of each solder joint with the standard waveform to determine whether the welding quality is qualified; see attached diagram. Figure 9 The waveforms for the different welding conditions are as follows: Waveform A represents the case where both solder joints are intact, with low and stable resistance values, and the waveform shows a rapid decrease followed by a sustained decrease; Waveform B represents the case where both solder joints are poorly soldered, with moderate to high resistance values ​​and large resistance fluctuations, and the waveform shows an incomplete decrease; Waveform C represents the case where both solder joints are detached, with an open circuit resistance value, and the waveform shows a straight line with no significant decrease.

[0029] Furthermore, the sorting robot 301 is triggered to move qualified electrode sheets to qualified channel 302 and unqualified electrode sheets to unqualified channel 303, thus completing online rapid sorting. Example

[0030] Based on Example 1, further improvements can be made by directly integrating the roller probe detection sensor into the electrode plate welding production line. That is, the roller probe detection sensor is integrated into the back end of the electrode plate ultrasonic welding device, sharing the same conveying device, realizing direct detection after welding, and improving the production line efficiency.

[0031] 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 a feeding module (10), a detection module (20), a discharging module (30), and a control module (40), wherein: The feeding module (10) is used to transport the electrode sheet (100) that has been welded with the tab (1001) to the testing table (201), and includes a feeding conveyor belt (101) and a positioning guide mechanism (102). The positioning and guiding mechanism (102) includes a three-dimensional measurement video head (1021) and an adjustable guide rail (1022). The three-dimensional measurement video head (1021) is installed above the feeding conveyor belt (101) and is used to measure and obtain the size information of the electrode sheet (100); The adjustable guide rail (1022) is used to guide the electrode sheet (100) onto the detection stage (201); The detection module (20) includes a detection stage (201), a detection robot (202), and a roller probe detection sensor (203) installed at the end of the detection robot (202). The testing station (201) is provided with a testing station (2011). Below the testing station (2011) is a pneumatic adsorption device (2012) for adsorbing the electrode sheet (100) to make it flat, and a sensing sensor for detecting whether the electrode sheet (100) is placed in place and generating a positioning signal. The roller-type probe detection sensor (203) includes a roller base (2031), a circuit module, a graded rolling mechanism (2033), and a clamping probe (2034). The roller base (2031) is cylindrical, and multiple rows of probe groups (2035) are evenly distributed along the circumference of the surface. Each row of probe groups (2035) contains multiple probe contacts arranged at equal intervals along the axial direction. The spacing between each probe contact matches the solder joints (1002) distributed on the electrode sheet (100), so that the probe contacts correspond one-to-one with the solder joints (1002). The circuit module is integrated inside the roller base (2031) and is used to apply a constant current to adjacent solder joints, measure the voltage drop, and calculate the output resistance value. The segmented rolling mechanism (2033) drives the rolling base (2031) to rotate in a segmented step manner, and the rotation angle of each segment corresponds to the spacing of the two rows of probe groups (2035). The clamping probe (2034) is fixedly installed on the detection robot (202); The unloading module (30) is used to sort qualified and unqualified electrode sheets (100) according to the test results, including a sorting robot (301), a qualified channel (302) and an unqualified channel (303). The control module (40) is electrically connected to the feeding module (10), the detection module (20), and the unloading module (30). The control module (40) is configured as follows: The electrode sheet (100) size measurement information obtained by the three-dimensional measurement video head (1021) is received, and the width of the adjustable guide rail (1022) is controlled to adapt to electrode sheets (100) of different sizes and widths. The signal from the sensing sensor is collected, and the roller probe detection sensor (203) on the detection robot (202) is controlled to perform light-touch rolling potential detection on the spot welding area of ​​the electrode sheet (100); Trigger the sorting action of the sorting robot (301).

2. An online rapid non-destructive testing method for the quality of metal thin film spot welding, employing the testing device described in claim 1, characterized in that, Includes the following steps: S1. Electrode loading and positioning The electrode sheet (100) with the tab (1001) welded is conveyed by the feeding conveyor belt (101). The size information of the electrode sheet (100) is measured by the three-dimensional measurement video head (1021). Based on the size information, the width of the adjustable guide rail (1022) is adjusted to fit the width of the electrode sheet (100). The electrode sheet (100) is guided to the inspection station (2011) of the inspection table (201) by the adjustable guide rail. S2. Electrode Adsorption and Placement Detection The pneumatic adsorption device (2012) is activated to adsorb the electrode plate (100) and make it flat. The sensor detects whether the electrode plate (100) is in place, generates a positioning signal and transmits it to the control module (40). S3. Roller-type potential detection After receiving the positioning signal, the control module (40) drives the detection robot (202) to move the roller probe detection sensor (203) to the spot welding area of ​​the electrode sheet (100). After completing the resistance detection of each two rows of probe groups (2035), the roller base (2031) rotates at a fixed angle to align the next two rows of probe groups (2035) with the adjacent weld points until the entire weld point area is covered. The circuit module calculates and outputs the resistance value between adjacent weld points in real time. S4. Quality Judgment and Sorting The control module (40) compares the waveform of the resistance value of each weld point with the standard waveform to determine whether the welding quality is qualified. The sorting robot (301) is triggered to sort qualified electrode sheets to qualified channel (302) and unqualified electrode sheets to unqualified channel (303), thus completing online rapid sorting.

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