Welding testing device and welding testing method

Abstract

A welding testing device and a welding testing method. The welding testing device is used for testing a welding seam (3) between a housing (11) and a top cover (12) of a battery (1). The welding testing device comprises: an image acquisition component (2) configured to photograph the welding seam (3), wherein the image acquisition component (2) is located above the outer side of the welding seam (3) and forms an included angle (α) with a height direction (z) of the battery (1); and a controller configured to obtain a protruding height (H) of the welding seam (3) relative to a reference plane area on an outer side wall of the housing (11) on the basis of a first distance (H1) between the image acquisition component (2) and the outer side wall of the housing (11), a second distance (H2) between the image acquisition component (2) and the welding seam (3), and the included angle (α), compare the protruding height (H) with a preset height threshold, and determining whether the protruding height of the welding seam (3) meets a standard.

Description

Welding detection device and welding detection method

[0001] This application claims priority to the Chinese patent application with application number 202410106550.5 filed with the Patent Office of China on January 25, 2024, and with the invention name “Welding Detection Device and Welding Detection Method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of battery assembly detection, and in particular to a welding detection device and a welding detection method. Background Art

[0003] The statements herein merely provide background information relevant to this application and do not necessarily constitute prior art. In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, power batteries, as the power source of electric vehicles, play an irreplaceable role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also growing. As core components of new energy vehicles, batteries have high requirements for operational reliability.

[0004] The battery's top cover and casing are connected by welding. Any defects in the welds can pose a significant safety risk to the battery. Currently, weld inspections on production lines rely on manual visual inspection and touch, which can be quite inaccurate in identifying weld defects.

[0005] Application Contents

[0006] The purpose of this application is to improve the accuracy of battery top cover weld detection.

[0007] According to a first aspect of the present application, a welding detection device is provided for detecting a weld between a battery housing and a top cover, the detection device comprising:

[0008] An image acquisition component is configured to photograph the weld, the image acquisition component is located obliquely above the outer side of the weld and forms an angle with the height direction of the battery; and

[0009] The controller is configured to calculate the protrusion height of the weld relative to the reference plane area on the outer wall of the shell based on the first distance between the image acquisition component and the outer wall of the shell, the second distance between the image acquisition component and the weld, and the angle, and compare the protrusion height with a preset height threshold to determine whether the protrusion height size of the weld is qualified.

[0010] This embodiment sets the image acquisition component at a suitable shooting angle, and obtains the distance between it and the outer wall of the shell and the weld through the image acquisition component, so as to obtain the protrusion height of the weld relative to the outer wall of the shell, and thus determine whether the protrusion height dimension of the weld is qualified. This method can detect the flange size defects of the battery in an automated manner, improve the detection accuracy, reduce missed detections, and thus reduce the risks brought by abnormal flange size to the battery working safety.

[0011] In some embodiments, an image acquisition component is provided on each side of the battery along its width direction, and the image acquisition component is configured to move relative to the weld along the length direction of the battery during the inspection process.

[0012] This embodiment can detect the protruding height of the battery weld relative to the outer side wall of the shell more quickly and efficiently, and the detection processes of the welds on both sides do not interfere with each other.

[0013] In some embodiments, the controller is configured to: determine that the weld protrusion height dimension is unqualified when there are multiple locations within a first preset distance range where the weld protrusion height exceeds a preset height threshold and the number exceeds a preset value in the extension direction of the weld.

[0014] This embodiment determines that there is a defect in the protrusion height dimension only when the protrusion height dimension exceeds the standard at multiple points in the extension direction of the weld. This judgment logic indicates that there is indeed a small section of the weld with a protrusion height exceeding the standard, which can reduce the probability of false detection, prevent errors in the detection results due to jitter of the image acquisition component during the relative movement of the battery, and improve the accuracy of welding detection.

[0015] In some embodiments, the controller is configured to select the maximum value of the protruding height of the weld in the height direction at the same position in the extension direction of the weld.

[0016] This embodiment selects the maximum value of the protruding height of the weld in the height direction for judgment, which can truly reflect whether the protruding height dimension of the weld at a specific position in the extension direction exceeds the standard, reduce the probability of missed detection, and improve the accuracy of weld detection.

[0017] In some embodiments, the reference plane region is preset to be spaced apart from the weld in the height direction.

[0018] This embodiment takes into account that the area below the weld is easily affected by the high welding temperature and may cause slight deformation or residual solder, resulting in poor flatness of the shell surface immediately below the weld. Therefore, the reference plane area and the weld area are spaced apart to avoid the uneven area below the weld, improve the flatness of the reference plane area, and thus improve the accuracy of the weld protrusion height detection.

[0019] In some embodiments, the controller is configured to divide the weld into multiple detection areas in its extension direction, and fit a sub-reference plane area corresponding to the outer surface of the shell in each detection area, and when obtaining the protruding height of the weld in each detection area, the corresponding sub-reference plane area is selected for calculation.

[0020] This embodiment is divided into multiple detection areas in the extension direction of the weld. When the surface area of ​​the battery shell is large and easily deformed, the true protrusion height of the weld can be obtained more accurately, thereby improving the accuracy of the weld protrusion height detection.

[0021] In some embodiments, the controller is configured to establish at least one plane parallel to the outer wall of the shell in the image and intersect with the weld. The resulting intersection line is the contour line of the weld surface, multiple points on the intersection line are fitted to a spatial straight line, the distance from the multiple points on the intersection line to the spatial straight line is calculated, and the distance is compared with a preset distance threshold to determine whether there are defects in the appearance of the weld.

[0022] This embodiment determines whether there are appearance defects based on the fluctuation of each point on the weld contour line relative to a fitted spatial line. This allows for further determination of appearance defects in the weld based on the protrusion height of the weld relative to the outer wall of the shell obtained by the image acquisition component, enabling a more comprehensive assessment of weld quality. Furthermore, the image acquisition component is positioned at an angle α relative to the height direction, enabling a more comprehensive acquisition of images of each contour region within the weld cross-section, enabling a more comprehensive assessment of appearance defects in the weld. Furthermore, when determining the fluctuation of each point on the contour line, a spatial line is fitted to multiple points on the intersecting line, serving as a baseline for determining the fluctuation of each point on the contour line. This compensates for errors in determining the fluctuation of each point due to an upward or downward tilt of the overall weld contour.

[0023] In some embodiments, the controller is configured to determine that the weld has an appearance defect if points with distances exceeding a preset distance threshold continuously appear in the weld in the extension direction of the weld within a second preset distance range.

[0024] This embodiment determines that the weld has an appearance defect only when multiple points in the extension direction of the weld exceed a preset distance threshold. This can reduce the probability of false detection, prevent errors in the detection results due to jitter of the image acquisition component during the relative movement of the battery, and improve the accuracy of welding appearance detection.

[0025] In some embodiments, the controller is configured to determine the defect type of the weld appearance based on the deviation direction and position of the point exceeding a preset distance threshold relative to the spatial straight line when there is a defect in the weld appearance.

[0026] This embodiment can locate the type of weld appearance defect based on the fluctuation direction of the point exceeding the preset distance threshold, so as to further locate the defect type when an appearance defect exists, so as to adjust the welding process in time according to the type of welding appearance defect during the production process.

[0027] According to a second aspect of the present application, a welding detection method is provided for detecting a weld between a battery housing and a top cover. The welding detection method includes a weld protrusion height detection step, which includes:

[0028] Determining a protrusion height of the weld relative to a reference surface area on the outer wall of the housing based on a first distance between the image acquisition component and the outer wall of the housing, a second distance between the image acquisition component and the weld, and an angle; wherein the image acquisition component is configured to photograph the weld, and the image acquisition component is located obliquely above and outside the weld and forms an angle with a height direction of the battery;

[0029] Compare the protrusion height with the preset height threshold to determine whether the weld protrusion height dimension is qualified.

[0030] In some embodiments, comparing the protrusion height with a preset height threshold to determine whether the weld protrusion height dimension is qualified includes:

[0031] In the extension direction of the weld, if points with protrusion heights exceeding a preset height threshold continuously appear in the weld within a first preset distance range, the weld protrusion height dimension is determined to be unqualified.

[0032] In some embodiments, at the same position in the extension direction of the weld, the maximum protruding height of the weld in the height direction is selected.

[0033] In some embodiments, selecting a reference surface area on the outer side wall of the housing includes:

[0034] In the height direction, select the base plane area and weld interval settings.

[0035] In some embodiments, the weld protrusion height detection step further includes:

[0036] Divide the weld into multiple inspection areas along its extension direction;

[0037] A sub-reference plane region is fitted corresponding to each detection area on the outer surface of the shell, and the reference plane region includes multiple sub-reference plane regions;

[0038] When obtaining the protruding height of the weld in each detection area, the corresponding sub-reference surface area is selected for calculation.

[0039] In some embodiments, the welding inspection method further includes a weld appearance defect inspection step, and the weld appearance defect inspection step includes:

[0040] Establishing at least one plane parallel to the outer wall of the shell in the image to intersect with the weld, and the obtained intersection line is the contour line of the weld surface;

[0041] Take multiple points on the intersection line to fit the space line, and calculate the distances from the multiple points on the intersection line to the space line;

[0042] The distance is compared with a preset distance threshold to determine whether there are defects in the weld appearance.

[0043] In some embodiments, comparing the distance with a preset distance threshold to determine whether the weld appearance has defects includes:

[0044] In the extension direction of the weld, if points whose distances exceed a preset distance threshold continuously appear in the weld within a second preset distance range, it is determined that the weld has an appearance defect.

[0045] In some embodiments, the weld appearance defect detection step further includes:

[0046] In the case of defects in the weld appearance, the defect type of the weld appearance is determined based on the deviation direction and position of the point exceeding the preset distance threshold relative to the spatial straight line. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0048] FIG1 is a schematic diagram of the welding detection device of the present application in which image acquisition components are respectively arranged on both sides of the battery.

[0049] FIG2 is a schematic diagram showing the positional relationship between the image acquisition component and the battery.

[0050] FIG3 is a schematic diagram of a normal weld between the top cover and the shell of the battery.

[0051] Figure 4 is a diagram showing the principle of calculating the protruding height of the weld.

[0052] FIG5 is a schematic diagram showing that a sub-reference plane area is fitted corresponding to each detection area on the outer surface of the housing.

[0053] 6A to 6E are schematic diagrams of welds with different defects.

[0054] FIG. 7A is a schematic diagram showing the outline of a weld-qualified product.

[0055] FIG7B is a schematic diagram showing the outline of a product with unqualified welds.

[0056] FIG8 is a schematic diagram of fitting a spatial straight line to multiple points on a contour line and determining the appearance defects of a weld by judging the fluctuation of the contour line based on the spatial straight line.

[0057] In the drawings, the drawings are not drawn to scale.

[0058] Marking instructions: 1. Battery; 11. Housing; 12. Top cover; 2. Image acquisition component; 3. Welding seam. DETAILED DESCRIPTION

[0059] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0060] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0061] This application uses descriptions of directions or positional relationships such as "up", "down", "top", "bottom", "front", "back", "inside" and "outside" to facilitate the description of this application, and does not indicate or imply that the device referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, it should not be understood as limiting the scope of protection of this application.

[0062] Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Perpendicular" does not strictly refer to perpendicularity, but rather to the tolerances allowed. "Parallel" does not strictly refer to parallelism, but rather to the tolerances allowed. The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application.

[0063] It should also be noted that, in the description of this application, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0064] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least some embodiments of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0065] Current battery cells usually include a shell and an electrode assembly housed in the shell, and the shell is filled with an electrolyte. The electrode assembly is mainly formed by stacking or winding a first electrode sheet and a second electrode sheet with opposite polarities, and an insulating member, such as a diaphragm, is usually provided between the first electrode sheet and the second electrode sheet. The portions of the first electrode sheet and the second electrode sheet coated with active material constitute the main body of the electrode assembly, and the portions of the first electrode sheet and the second electrode sheet not coated with active material each constitute the first electrode tab and the second electrode tab. In a battery cell, the first electrode sheet can be a positive electrode sheet, including a positive electrode current collector and a positive electrode active material layer provided on both sides of the positive electrode current collector. The positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate made of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The positive electrode active material layer may include at least one of the following materials: lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. The second electrode sheet may be a negative electrode sheet, including a negative electrode current collector and a negative electrode active material layer provided on both sides of the negative electrode current collector. The negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The negative electrode active material layer can adopt the negative electrode active material for batteries known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material and lithium titanate, etc. Optionally, the first pole piece can also be a negative pole piece, and the corresponding second pole piece is a positive pole piece. The first pole piece and the second pole piece can be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery cell, the positive electrode active material and the negative electrode active material react with the electrolyte, and the pole pieces connect the electrode terminals to form a current loop.

[0066] The battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be recharged to activate the active material after the battery cell is discharged and can be used continuously.

[0067] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0068] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, and a polygonal battery. The polygonal battery is, for example, a hexagonal battery, etc. There is no special limitation in this application.

[0069] Taking battery cells as an example, the top cover and shell of the battery cell are connected by welding. Generally, the weld will protrude from the outer wall of the shell, which can also be called a flange. If the protruding height is abnormal, the adjacent battery cells will fit tightly during assembly. The protruding weld will exert pressure on the adjacent battery cells, causing the shell to deform or damage the insulating film, bringing the risk of short circuit, thereby posing a great safety risk to the battery.

[0070] Currently, welds are inspected on production lines through a combination of manual visual inspection and touch. However, manual inspection is inefficient, and uncontrollable factors can easily lead to missed inspections of weld defective products, resulting in low accuracy.

[0071] Based on the above problems, the present application proposes a welding detection device, as shown in Figures 1 and 2, for detecting the weld 3 between the shell 11 and the top cover 12 of the battery 1, the detection device including: an image acquisition component 2, configured to photograph the weld 3, the image acquisition component 2 is located obliquely above the outside of the weld 3 and forms an angle α with the height direction z of the battery 1; and a controller, configured to obtain the protrusion height H of the weld 3 relative to the reference plane area on the outer wall of the shell 11 based on the first distance H1 between the image acquisition component 2 and the outer wall of the shell 11, the second distance H2 between the image acquisition component 2 and the weld 3, and the angle α, compare the protrusion height H with a preset height threshold, and determine whether the protrusion height size of the weld 3 is qualified.

[0072] The battery 1 may be a battery cell or a battery pack, and the top cover 12 is provided at the end of the housing 11 along the height direction z. The image acquisition component 2 may be a camera, such as a 3D camera, which can obtain the distance by the time difference between laser emission and reception.

[0073] If the image acquisition component 2's field of view can capture the entire weld 3, the image acquisition component 2 can be fixed relative to the battery 1. If the image acquisition component 2's field of view cannot capture the entire weld 3, the image acquisition component 2 and the weld 3 can be moved relative to each other to obtain images of different locations on the weld 3. Movement of either the battery 1 or the image acquisition component 2 is optional. For example, if the battery 1 is rectangular, either the image acquisition component 2 or the battery 1 can be moved. Alternatively, if the battery 1 is cylindrical, the image acquisition component 2 can be fixed while the battery 1 rotates about its central axis.

[0074] As shown in FIG2 , the image acquisition component 2 is located obliquely above and outside the weld 3 and forms an angle α with the height direction z of the battery 1. The shooting direction of the image acquisition component 2 forms an angle α with the height direction z of the battery 1, and the shooting surface of the image acquisition component 2 is parallel to the tangent of the weld 3. Optionally, the range of the angle α is 45°±5°. Within this range, the protrusion height of the weld 3 measured has high repeatability and consistency, and can fully detect other defects in the weld 3. This prevents the image acquisition component 2 from partially losing the protrusion height dimension data due to a too small angle α, and also prevents the image acquisition component 2 from partially losing the protrusion height dimension data due to a too large angle α, although better protrusion height dimension data of the weld 3 can be obtained, but other defects of the weld 3 cannot be identified.

[0075] The controller is configured to determine a protrusion height H of the weld 3 relative to a reference surface area on the outer wall of the housing 11 based on a first distance H1 between the image acquisition component 2 and the outer wall of the housing 11, a second distance H2 between the image acquisition component 2 and the weld 3, and an angle α, and compare the protrusion height H with a preset height threshold to determine whether the protrusion height dimension of the weld 3 is qualified. For example, as shown in FIG4 , based on the triangular reflection principle, the protrusion height H is calculated using the following formula: H = (H1-H2-L / tanα)*sinα, where L is the width of the light irradiated on the weld 3 and the reference surface area in the height direction z.

[0076] The first distance H1 can be directly determined according to the installation position of the image acquisition component 2 and the installation position and size of the battery 1 . The second distance H2 requires real-time acquisition of data at multiple positions along the extension direction of the weld 3 .

[0077] In this embodiment, the image acquisition component 2 is set at a suitable shooting angle, and the distance between the image acquisition component 2 and the outer wall of the shell 11 and the weld 3 is obtained through the image acquisition component 2, thereby obtaining the protrusion height H of the weld 3 relative to the outer wall of the shell 11, and determining whether the protrusion height dimension of the weld 3 is qualified. This method can detect the flange size defects of the battery 1 in an automated manner, improve the detection accuracy, reduce missed detections, and thus reduce the risks brought by abnormal flange size to the working safety of the battery 1.

[0078] In some embodiments, an image acquisition component 2 is provided on each side of the battery 1 along its width direction, and the image acquisition component 2 is configured to move along the length direction of the battery 1 relative to the weld 3 during the detection process.

[0079] The battery 1 is rectangular, and the image acquisition components 2 are positioned opposite each other along its width, forming the same angle α with the height z of the battery 1. For example, the battery 1 can be moved along its length to allow the welds 3 on its two long sides to move relative to the image acquisition components 2 on either side. Alternatively, the image acquisition components 2 on both sides can be moved along the length of the battery 1. Alternatively, image acquisition components 2 can be positioned on either side of the length of the battery 1 to inspect the welds 3 on its two short sides.

[0080] This embodiment can detect the protruding height of the weld 3 of the battery 1 relative to the outer wall of the shell 11 more quickly and efficiently, and the detection processes of the welds 3 on both sides do not interfere with each other.

[0081] In some embodiments, the controller is configured to: when there are multiple locations within a first preset distance range in the extension direction of the weld 3 where the protrusion height exceeds the preset height threshold and the number exceeds a preset value, determine that the protrusion height size of the weld 3 is unqualified.

[0082] For example, for a rectangular battery 1, the weld seam 3 on the long side of the battery 1 extends in the length direction of the battery 1, and the weld seam 3 on the short side of the battery 1 extends in the width direction of the battery 1. For a cylindrical battery 1, the weld seam 3 extends in a circular direction. As the image acquisition component 2 gradually moves relative to the weld seam 3, it acquires the second distance H2 in real time. Within a preset distance range, if the second distance H2 exceeds a preset height threshold at multiple points (the multiple points can be continuous or discontinuous) exceeding the preset value, the weld seam 3 is determined to have a protruding height dimension defect.

[0083] In this embodiment, a defect in the protrusion height dimension is determined to be present only when the protrusion height dimension exceeds the standard at multiple points in the extension direction of the weld 3. This judgment logic indicates that there is indeed a small section of the weld 3 with an excessive protrusion height, which can reduce the probability of false detection, prevent errors in the detection results due to jitter of the image acquisition component 2 during the relative movement of the battery 1, and improve the accuracy of welding detection.

[0084] In some embodiments, the controller is configured to select the maximum value of the protruding height of the weld 3 in the height direction z at the same position in the extension direction of the weld 3 .

[0085] As shown in Figure 5, the dashed grid area above represents the area where weld 3 is located. At the same position along the extension direction of weld 3, image acquisition component 2 acquires second distances H2 at multiple discrete points on the surface of weld 3 along the height direction z. Simultaneously, as image acquisition component 2 moves relative to weld 3, second distances H2 at multiple positions along the extension direction of weld 3 are acquired. When determining the protrusion height at a specific position along the extension direction of weld 3, the maximum protrusion height along the height direction z is used as the representation.

[0086] This embodiment selects the maximum value of the protruding height of the weld 3 in the height direction z for judgment, which can truly reflect whether the protruding height dimension of the weld 3 at a specific position in the extension direction exceeds the standard, reduce the probability of missed detection, and improve the detection accuracy of the weld 3.

[0087] In some embodiments, as shown in FIG. 5 , the reference plane region S is preset to be spaced apart from the weld seam 3 in the height direction z.

[0088] In FIG5 , the upper dashed box represents the weld area, and the lower dashed box represents the reference plane area S. The weld area and the reference plane area S are spaced apart. For example, the protrusion height detection area of ​​the weld 3 is set at 0-2.0 mm below the surface of the top cover 12 away from the housing 11, and the reference plane area S is set at 3.0 mm to 3.5 mm below the surface of the top cover 12 away from the housing 11. This numerical range can be set according to the actual width of the weld 3.

[0089] This embodiment takes into account that the area below the weld 3 is susceptible to slight deformation or residual solder due to the influence of high welding temperature, resulting in poor flatness of the surface of the shell 11 immediately below the weld 3. Therefore, the reference plane area S is spaced apart from the weld area to avoid the uneven area below the weld 3, thereby improving the flatness of the reference plane area S and thus improving the accuracy of the detection of the protruding height of the weld 3.

[0090] In some embodiments, as shown in Figure 5, the controller is configured to divide the weld 3 into multiple detection areas in its extension direction, and fit a sub-reference plane area S1 corresponding to the outer surface of the shell 11 in each detection area, and when obtaining the protruding height of the weld 3 in each detection area, the corresponding sub-reference plane area S1 is selected for calculation.

[0091] When the surface area of ​​the battery 1's housing 11 is large, deformation is likely to occur. For example, for a rectangular battery 1, the largest surface of the housing 11 is susceptible to deformation. Therefore, when inspecting the weld 3 on the long side of the battery 1, the weld 3 can be divided into multiple inspection areas along the length of the battery 1. The areas can be evenly divided, and the number of inspection areas can be set based on the length of the weld 3. The reference surface area S on the housing 11 is also divided into multiple sub-reference areas S1. The multiple inspection areas and the multiple sub-reference areas S1 are arranged in a one-to-one correspondence. Each inspection area has the same size as the corresponding sub-reference area S1 in the direction in which the weld 3 extends, and the inspection area and the corresponding sub-reference area S1 are spaced apart in the height direction z.

[0092] Optionally, when the surface area of ​​the shell 11 of the battery 1 is relatively small, only one integral reference surface area S may be provided.

[0093] This embodiment is divided into multiple detection areas in the extension direction of the weld 3. When the surface area of ​​the shell 11 of the battery 1 is large and easy to deform, the actual protrusion height of the weld 3 can be obtained more accurately, thereby improving the accuracy of the protrusion height detection of the weld 3.

[0094] In some embodiments, as shown in Figure 3, the controller is configured to establish at least one plane P parallel to the outer wall of the shell 11 in the image and intersect with the weld 3. The obtained intersection line is the contour line of the surface of the weld 3. Multiple points on the intersection line are fitted to a spatial straight line, and the distance from the multiple points on the intersection line to the spatial straight line is calculated. The distance is compared with a preset distance threshold to determine whether there is a defect in the appearance of the weld 3.

[0095] Among them, when 45°±5° is selected, the measured protrusion height of the weld 3 has high repeatability and consistency, and defects such as inner undercut and outer undercut can be detected. When α is less than 40°, the appearance defect of the outer undercut cannot be effectively identified because the weld 3 protrudes relative to the outer wall of the shell 11, causing the scanning data of the image acquisition component 2 to be partially lost. When α is greater than 50°, although relatively complete protrusion height dimension data of the weld 3 can be obtained, defects such as the inner undercut cannot be identified. For example, Figure 6A shows an outer undercut defect, i.e., a notch appears on the outer side of the weld 3; Figure 6B shows a burst point defect, i.e., a small dot appears on the surface of the weld 3; Figure 6C shows an inner undercut defect, i.e., a notch appears on the inner side of the weld 3; Figure 6D shows an outer polarization defect, i.e., the welding position of the weld 3 is too far outward, causing the portion protruding from the outer surface of the shell 11 to be missing; Figure 6E shows an inner polarization defect, i.e., the welding position of the weld 3 is too inward, causing it to retract inward relative to the outer surface of the shell 11.

[0096] As shown in Figure 3, at least one plane P parallel to the outer wall of the shell 11 is established in the image to intersect with the weld 3. A single plane P can be set, or multiple planes P can be set at intervals perpendicular to the sidewall of the shell 11 to obtain contour lines at multiple different locations on the surface of the weld 3, thereby more comprehensively detecting surface defects on the weld 3. Furthermore, each intersecting line represents a contour line of the weld 3 at a specific location perpendicular to the sidewall of the shell 11. Multiple points on this contour line are fitted to a spatial straight line, and this spatial straight line is used as a baseline. The degree of deviation of the multiple points from the baseline is calculated, and if the degree of deviation exceeds the standard, it is determined that the weld 3 has a surface defect near that point.

[0097] For the contour line formed by a certain plane P, Figure 7A is a schematic diagram of the contour line of a qualified weld product. All points on the contour line are within the preset distance threshold range relative to the spatial straight line, and the fluctuation range is -2.16mm to -2.5mm; Figure 7B is a schematic diagram of the contour line of an unqualified weld product. Some points on the contour line fluctuate more greatly relative to the spatial straight line, exceeding the preset distance threshold, and the fluctuation range is -2.14mm to -2.7mm. The defect type can be determined according to the fluctuation direction of the point. If it fluctuates upward, it means that there is a bulge on the surface of the weld 3. If it fluctuates downward, it means that there is a bite or burst point defect on the surface of the weld 3.

[0098] Since the fixture or positioning mechanism of the battery 1 inevitably has positioning errors, the overall contour line may rise or fall uniformly. As shown in Figure 8, if the fluctuation of each point on the contour line is determined only by the horizontal straight line, the surface condition of the weld 3 cannot be truly reflected. By fitting a spatial straight line with multiple points on the intersection line as the reference line for judging the fluctuation of each point on the contour line, the error caused by the overall upward or downward tilt of the weld 3 contour in judging the fluctuation of each point can be compensated.

[0099] This embodiment determines whether there are appearance defects based on the fluctuation of each point on the contour line of the weld 3 relative to a fitted spatial line. Based on the protrusion height of the weld 3 relative to the outer wall of the housing 11 obtained by the image acquisition component 2, the appearance defects of the weld 3 can be further determined, allowing for a more comprehensive inspection of the quality of the weld 3. Furthermore, the image acquisition component 2 is positioned at an angle α relative to the height direction z, allowing for a more comprehensive acquisition of images of each contour region within the cross-section of the weld 3, enabling a more comprehensive inspection of the appearance defects of the weld 3. Furthermore, when determining the fluctuation of each point on the contour line, a spatial line is fitted to multiple points on the intersecting line, serving as a baseline for determining the fluctuation of each point on the contour line. This compensates for errors in determining the fluctuation of each point due to the upward or downward tilt of the overall contour of the weld 3.

[0100] In some embodiments, the controller is configured to determine that the weld 3 has an appearance defect if points with distances exceeding a preset distance threshold continuously appear in the extension direction of the weld 3 within a second preset distance range.

[0101] Among them, the image acquisition component 2 obtains the image of the weld 3 in real time during the process of gradually moving relative to the weld 3. If multiple points appear continuously on the contour line of the weld 3 in the image, and the distance from the straight line of the fitting space exceeds the preset distance threshold, it is determined that the weld 3 has an appearance defect.

[0102] In this embodiment, the weld 3 is judged to have an appearance defect only when multiple points appear in the extension direction of the weld 3 that exceed a preset distance threshold. This can reduce the probability of false detection, prevent errors in the detection results caused by jitter of the image acquisition component 2 during the relative movement of the battery 1, and improve the accuracy of welding appearance detection.

[0103] In some embodiments, the controller is configured to determine the defect type of the appearance of the weld 3 based on the deviation direction and position of the point exceeding the preset distance threshold relative to the spatial straight line when there is a defect in the appearance of the weld 3.

[0104] Among them, the defect type can be determined according to the fluctuation direction of the point. If it fluctuates upward, it means that a bulge appears on the surface of the weld 3. If it fluctuates downward, it means that a bite edge or a burst point defect appears on the surface of the weld 3.

[0105] This embodiment can locate the type of appearance defect of the weld 3 according to the fluctuation direction of the point exceeding the preset distance threshold, so as to further locate the defect type when an appearance defect exists, so as to adjust the welding process in time according to the type of welding appearance defect during the production process.

[0106] In some specific embodiments, as shown in FIG. 1 to FIG. 5 , a rectangular battery 1 is taken as an example to illustrate the working principle of the welding detection device of the present application.

[0107] Image acquisition components 2 are provided on both sides of the battery 1 along its width. These components 2 are positioned relative to each other and form the same angle α with the height direction z of the battery 1. The angle α is within the range of 45°±5°. For example, the battery 1 and the image acquisition components 2 can move relative to each other along the length of the battery 1 to allow the welds 3 on the two long sides of the battery 1 to move relative to the image acquisition components 2 on both sides. Alternatively, image acquisition components 2 can be provided on both sides of the battery 1 along its length to inspect the welds 3 on the two short sides of the battery 1.

[0108] During relative motion between the battery 1 and the image acquisition component 2 along the length of the battery 1, the image acquisition component 2 can obtain a first distance H1 between the image acquisition component 2 and the outer wall of the housing 11, a second distance H2 between the image acquisition component 2 and the weld 3, and capture an image of the weld 3. This allows the controller to determine a protrusion height H of the weld 3 relative to a reference plane on the outer wall of the housing 11 based on the first distance H1, the second distance H2, and the angle α, and to determine whether the protrusion height dimension of the weld 3 is acceptable. Furthermore, the controller can establish at least one plane P parallel to the outer wall of the housing 11 in the captured image, intersecting the weld 3 with the obtained intersection line, and then fit a spatial line to the surface of the weld 3. The controller then calculates the distances from the multiple points on the intersection line to the spatial line and compares the distances with a preset distance threshold to determine whether the appearance of the weld 3 is defective. This embodiment enables quality inspection of defects in the weld 3, including protrusion height inspection and appearance defect inspection, improving inspection accuracy and thereby enhancing the operational safety of the battery 1.

[0109] Secondly, the present application provides a welding detection method for detecting the weld 3 between the shell 11 and the top cover 12 of the battery 1. The welding detection method includes a weld 3 protrusion height detection step, and the weld 3 protrusion height detection step includes:

[0110] The protrusion height of the weld seam 3 relative to the reference plane area on the outer wall of the housing 11 is obtained based on a first distance between the image acquisition component 2 and the outer wall of the housing 11, a second distance between the image acquisition component 2 and the weld seam 3, and an angle α. The image acquisition component 2 is configured to capture the weld seam 3, and the image acquisition component 2 is located obliquely above the outer side of the weld seam 3 and forms an angle α with the height direction z of the battery 1.

[0111] The protrusion height is compared with a preset height threshold to determine whether the protrusion height of the weld 3 is qualified.

[0112] In this embodiment, the image acquisition component 2 is set at a suitable shooting angle, and the distance between the image acquisition component 2 and the outer wall of the shell 11 and the weld 3 is obtained through the image acquisition component 2, thereby obtaining the protrusion height H of the weld 3 relative to the outer wall of the shell 11, and determining whether the protrusion height dimension of the weld 3 is qualified. This method can detect the flange size defects of the battery 1 in an automated manner, improve the detection accuracy, reduce missed detections, and thus reduce the risks brought by abnormal flange size to the working safety of the battery 1.

[0113] In some embodiments, the protrusion height is compared with a preset height threshold to determine whether the protrusion height dimension of the weld 3 is qualified, including: in the extension direction of the weld 3, if there are consecutive points in the weld 3 where the protrusion height exceeds the preset height threshold within a first preset distance range, then the protrusion height dimension of the weld 3 is determined to be unqualified.

[0114] In this embodiment, a defect in the protrusion height dimension is determined to be present only when the protrusion height dimension exceeds the standard at multiple points in the extension direction of the weld 3. This judgment logic indicates that there is indeed a small section of the weld 3 with an excessive protrusion height, which can reduce the probability of false detection, prevent errors in the detection results due to jitter of the image acquisition component 2 during the relative movement of the battery 1, and improve the accuracy of welding detection.

[0115] In some embodiments, at the same position in the extension direction of the weld 3, the maximum protruding height of the weld 3 in the height direction z is selected.

[0116] As shown in Figure 5, the dashed grid area above represents the area where weld 3 is located. At the same position along the extension direction of weld 3, image acquisition component 2 acquires second distances H2 at multiple discrete points on the surface of weld 3 along the height direction z. Simultaneously, as image acquisition component 2 moves relative to weld 3, second distances H2 at multiple positions along the extension direction of weld 3 are acquired. When determining the protrusion height at a specific position along the extension direction of weld 3, the maximum protrusion height along the height direction z is used as the representation.

[0117] This embodiment selects the maximum value of the protruding height of the weld 3 in the height direction z for judgment, which can truly reflect whether the protruding height dimension of the weld 3 at a specific position in the extension direction exceeds the standard, reduce the probability of missed detection, and improve the detection accuracy of the weld 3.

[0118] In some embodiments, selecting the reference plane area S on the outer wall of the shell 11 includes: in the height direction z, selecting the reference plane area S and setting it apart from the weld 3.

[0119] This embodiment takes into account that the area below the weld 3 is susceptible to slight deformation or residual solder due to the influence of high welding temperature, resulting in poor flatness of the surface of the shell 11 immediately below the weld 3. Therefore, the reference plane area S is spaced apart from the weld area to avoid the uneven area below the weld 3, thereby improving the flatness of the reference plane area S and thus improving the accuracy of the detection of the protruding height of the weld 3.

[0120] In some embodiments, the step of detecting the protrusion height of the weld 3 further includes:

[0121] Dividing the weld seam 3 into a plurality of detection areas in its extending direction;

[0122] A sub-reference plane region S1 is fitted on the outer surface of the housing 11 in each detection area, and the reference plane region S includes multiple sub-reference plane regions S1;

[0123] When obtaining the protruding height of the weld seam 3 in each detection area, the corresponding sub-reference plane area S1 is selected for calculation.

[0124] The three steps are performed sequentially. This embodiment divides the weld 3 into multiple detection areas along its extension direction. When the battery 1 has a large surface area and is easily deformed, the true protrusion height of the weld 3 can be obtained more accurately, thereby improving the accuracy of the weld 3 protrusion height detection.

[0125] In some embodiments, referring to FIG3 , the welding inspection method further includes a step of inspecting the appearance defects of the weld 3 , and the step of inspecting the appearance defects of the weld 3 includes:

[0126] In the image, at least one plane P parallel to the outer wall of the shell 11 is established to intersect with the weld 3, and the obtained intersection line is the contour line of the surface of the weld 3;

[0127] Take multiple points on the intersection line to fit the space line, and calculate the distances from the multiple points on the intersection line to the space line;

[0128] The distance is compared with a preset distance threshold to determine whether there is a defect in the appearance of the weld 3.

[0129] Among them, the above three steps are performed sequentially. This embodiment determines whether there are appearance defects based on the fluctuation of each point on the contour line of the weld 3 relative to the fitted spatial straight line. It can further judge the appearance defects of the weld 3 on the basis of the protruding height of the weld 3 relative to the outer wall of the shell 11 obtained by the image acquisition component 2, and can perform a more comprehensive inspection of the quality of the weld 3. Moreover, the image acquisition component 2 is set at an angle α relative to the height direction z, which can more comprehensively obtain the image of each contour area in the cross section of the weld 3, and more comprehensively detect the appearance defects of the weld 3. In addition, when determining the fluctuation of each point on the contour line, by taking multiple points on the intersection line to fit a spatial straight line as the reference line for judging the fluctuation of each point on the contour line, it can compensate for the error caused by the overall upward or downward tilt of the weld 3 contour in judging the fluctuation of each point.

[0130] In some embodiments, comparing the distance with a preset distance threshold to determine whether there is an appearance defect in the weld 3 includes: in the extension direction of the weld 3, if points with distances exceeding the preset distance threshold continuously appear in the weld 3 within a second preset distance range, then it is determined that the weld 3 has an appearance defect.

[0131] In this embodiment, the weld 3 is judged to have an appearance defect only when multiple points appear in the extension direction of the weld 3 that exceed a preset distance threshold. This can reduce the probability of false detection, prevent errors in the detection results caused by jitter of the image acquisition component 2 during the relative movement of the battery 1, and improve the accuracy of welding appearance detection.

[0132] In some embodiments, the step of detecting appearance defects of weld 3 also includes: when there are defects in the appearance of weld 3, determining the defect type of the appearance of weld 3 based on the deviation direction and position of the point exceeding the preset distance threshold relative to the spatial straight line.

[0133] This embodiment can locate the type of appearance defect of the weld 3 according to the fluctuation direction of the point exceeding the preset distance threshold, so as to further locate the defect type when an appearance defect exists, so as to adjust the welding process in time according to the type of welding appearance defect during the production process.

[0134] The controller described above may be a general-purpose processor, a programmable logic controller (PLC), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any appropriate combination thereof, for performing the functions described in the present disclosure.

[0135] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A welding detection device for detecting the weld between the housing and the top cover of a battery, the detection device comprising: An image acquisition component configured to capture the weld, the image acquisition component being located obliquely above the outside of the weld and forming an angle with the height direction of the battery; And A controller configured to obtain the protruding height of the weld relative to the reference plane area on the outer wall of the housing based on a first distance between the image acquisition component and the outer wall of the housing, a second distance between the image acquisition component and the weld, and the angle, compare the protruding height with a preset height threshold, and determine whether the protruding height dimension of the weld is qualified; and configured to establish at least one plane parallel to the outer wall of the housing in the image to intersect with the weld, the obtained intersection line being the contour line of the weld surface, take multiple points on the intersection line to fit a space straight line, calculate the distances from the multiple points on the intersection line to the space straight line, and compare the distances with a preset distance threshold to determine whether there are defects in the appearance of the weld.

2. The welding detection device according to claim 1, wherein, One such image acquisition component is provided on each of the two sides of the battery in its width direction, and the image acquisition component is configured to move relative to the weld in the length direction of the battery during the detection process.

3. The welding detection device according to claim 1 or 2, wherein, The controller is configured to: In the extending direction of the weld, if there are multiple positions where the protruding height of the weld exceeds the preset height threshold within a first preset distance range and the number exceeds the preset value, determine that the protruding height dimension of the weld is unqualified.

4. The welding detection device according to any one of claims 1-3, wherein, The controller is configured to select the maximum value of the protruding height of the weld in the height direction at the same position in the extending direction of the weld.

5. The welding detection device according to any one of claims 1-4, wherein, The reference plane area is preset to be spaced from the weld in the height direction.

6. The welding detection device according to any one of claims 1-5, wherein, The controller is configured to divide the weld into multiple detection areas in its extending direction, and fit a sub-reference plane area to the outer surface of the housing in each of the detection areas, and when obtaining the protruding height of the weld in each of the detection areas, select the corresponding sub-reference plane area for calculation.

7. The welding detection device according to any one of claims 1-6, wherein, The controller is configured to: In the extending direction of the weld, if points where the distance exceeds the preset distance threshold continuously appear within a second preset distance range, determine that there are appearance defects in the weld.

8. The welding detection device according to any one of claims 1-7, wherein, The controller is configured to, when there are appearance defects in the weld, determine the type of appearance defect of the weld according to the deviation direction and the position of the points exceeding the preset distance threshold relative to the space straight line.

9. A welding detection method for detecting the weld between the housing and the top cover of a battery, the welding detection method including a weld protruding height detection step and a weld appearance defect detection step, wherein: The weld protruding height detection step includes: The protruding height of the weld seam relative to the reference plane area on the outer side wall of the housing is obtained based on the first distance between the image acquisition component and the outer side wall of the housing, the second distance between the image acquisition component and the weld seam, and the included angle; wherein, the image acquisition component is configured to photograph the weld seam, the image acquisition component is located obliquely above the outside of the weld seam and forms the included angle with the height direction of the battery; Compare the protruding height with a preset height threshold to determine whether the size of the protruding height of the weld seam is qualified; The weld seam appearance defect detection step includes: Establish at least one plane parallel to the outer side wall of the housing in the image to intersect with the weld seam, and the obtained intersection line is the contour line of the weld seam surface; Take multiple points on the intersection line to fit a space straight line, and calculate the distances from the multiple points on the intersection line to the space straight line; Compare the distance with a preset distance threshold to determine whether there are defects in the appearance of the weld seam.

10. The welding detection method according to claim 9, wherein, Compare the protruding height with a preset height threshold to determine whether the size of the protruding height of the weld seam is qualified, including: In the extending direction of the weld seam, if points where the protruding height exceeds the preset height threshold continuously appear within a first preset distance range, it is determined that the size of the protruding height of the weld seam is unqualified.

11. The welding detection method according to claim 9 or 10, wherein, At the same position in the extending direction of the weld seam, select the maximum value of the protruding height of the weld seam in the height direction.

12. The welding detection method according to any one of claims 9-11, wherein, Selecting the reference plane area on the outer side wall of the housing includes: In the height direction, select the reference plane area to be spaced from the weld seam.

13. The welding detection method according to any one of claims 9-12, wherein, The weld seam protruding height detection step further includes: Divide the weld seam into multiple detection areas in its extending direction; Correspondingly fit a sub-reference plane area on the outer surface of the housing in each of the detection areas, and the reference plane area includes multiple sub-reference plane areas; Wherein, when obtaining the protruding height of the weld seam in each of the detection areas, select the corresponding sub-reference plane area for calculation.

14. The welding detection method according to any one of claims 9-13, wherein, Compare the distance with a preset distance threshold to determine whether there are defects in the appearance of the weld seam, including: In the extending direction of the weld seam, if points where the distance exceeds the preset distance threshold continuously appear within a second preset distance range, it is determined that there are appearance defects in the weld seam.

15. The welding detection method according to any one of claims 9-14, wherein, The weld seam appearance defect detection step further includes: In the case where there are defects in the appearance of the weld seam, determine the defect type of the weld seam appearance according to the deviation direction and the position of the points exceeding the preset distance threshold relative to the space straight line.

Images