A method for extracting acoustic reflectivity of a power battery busbar welding point

Abstract

This invention addresses the limitations of existing technologies by proposing a method for extracting the acoustic reflectivity of busbar weld points in power batteries. It converts the grayscale information of ultrasonic phased array C-scan images into acoustic reflectivity, which is closely related to the defect characteristics of the workpiece under test. This method can be used for the detection and evaluation of internal defects in the workpiece. The acoustic reflectivity distribution calculated using this method can also serve as one of the bases for locating the welding area and can be further converted into other relevant evaluation indicators, improving the accuracy of detection. It is particularly suitable for the detection of internal defects in the welding area of ​​workpieces subjected to arc welding and ultrasonic welding using phased array ultrasonic imaging, as well as the evaluation of relevant indicators such as effective weld points and bonding areas.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic phased array C-scan imaging technology, specifically to a method for extracting the acoustic reflectivity of a power battery busbar solder joint. Background Technology

[0002] Phased array ultrasonic testing technology has been developed and applied as a novel technology. It can be combined with image processing technology to perform non-destructive testing on workpieces. In the new energy vehicle industry, ultrasonic phased array technology is used to perform C-scan imaging on the power battery busbar, and image processing can be used to extract welding defect information of the tested workpiece.

[0003] As shown in the Chinese invention patent with the authorization announcement date of 2022-02-18: A defect detection method, device, equipment and storage medium, it determines the defect area of ​​the object to be detected based on the ultrasonic pulse reflection C-scan image of the object to be detected; extracts the defect A-scan image portion from the ultrasonic pulse reflection A-scan image of the object to be detected based on the location of the defect area; and determines the defect nature of the object to be detected based on the defect A-scan image portion.

[0004] A common problem with this type of ultrasonic phased array C-scan image is that the image information is mainly reflected in the image's grayscale information. If the image's grayscale information is directly used as an evaluation metric, it will be greatly affected by factors such as noise, gain, and environmental variables. Therefore, the existing technology still has certain limitations. Summary of the Invention

[0005] To address the limitations of existing technologies, this invention proposes a method for extracting the acoustic reflectivity of busbar solder joints in power batteries. The technical solution adopted by this invention is as follows:

[0006] A method for extracting the acoustic reflectivity of a busbar solder joint in a power battery includes the following steps:

[0007] S1, acquire the ultrasonic phased array C-scan image of the workpiece to be inspected;

[0008] S2, convert the ultrasonic phased array C-scan image into a grayscale image;

[0009] S3, Perform ROI region segmentation on the grayscale image to obtain ROI region images;

[0010] S4, Locate the background area and the welding area of ​​the workpiece to be inspected on the ROI area image;

[0011] S5, Based on the location of the weld points on the workpiece to be inspected, the welding area is divided into several rectangular weld point areas;

[0012] S6, obtain the average grayscale of the rectangular area of ​​the solder joint and the average grayscale of the background area;

[0013] S7. Obtain the acoustic reflectivity of the weld point of the workpiece to be inspected based on the average grayscale of the rectangular area of ​​the weld point and the average grayscale of the background area.

[0014] Compared to existing technologies, this invention converts the grayscale information of ultrasonic phased array C-scan images into acoustic reflectivity, which is closely related to the defect characteristics of the workpiece under test. This can be used for the detection and evaluation of internal defects in the workpiece under test. The acoustic reflectivity distribution calculated using this method can also serve as one of the bases for locating the welding area and can be further converted into other relevant evaluation indicators, thus improving the accuracy of detection. It is particularly suitable for phased array ultrasonic imaging to detect internal defects in the welding area of ​​workpieces such as arc welding and ultrasonic welding, and to evaluate relevant indicators such as effective weld points and bonding areas.

[0015] As a preferred embodiment, in step S2, channel detection is first performed on the ultrasonic phased array C-scan image:

[0016] If the ultrasound phased array C-scan image is a three-channel image, then the library function is used to convert the ultrasound phased array C-scan image into a grayscale image; if the ultrasound phased array C-scan image is a single-channel image, then no conversion is required, and step S3 is executed directly.

[0017] As a preferred embodiment, in step S3, after locating the welding area WED of the workpiece to be inspected, the area of ​​the ROI region image other than the welding area is used as the background area.

[0018] Furthermore, in step S3, a fast neighborhood search algorithm is used to locate the welding area WED of the workpiece to be inspected.

[0019] As a preferred embodiment, the size of the rectangular area of ​​the weld point is calculated based on the measurement results obtained from the actual welding area of ​​the workpiece to be inspected and the resolution of the ultrasonic phased array C-scan image; in the rectangular area of ​​the weld point, the size of the weld point is the tooth shape size of the welding head.

[0020] As a preferred embodiment, in step S6, the ratio obtained by dividing the average gray level of the rectangular area of ​​the weld point by the average gray level of the background area is used as the acoustic reflectivity of the weld point of the workpiece to be inspected.

[0021] As a preferred embodiment, in step S6, the acoustic reflectivity α of the weld point on the workpiece to be inspected is obtained using the following formula:

[0022]

[0023] Among them, g w g represents the average grayscale value of the rectangular area of ​​the solder joint. b This represents the average gray level of the background area.

[0024] This invention also includes the following:

[0025] A system for extracting the acoustic reflectivity of a power battery busbar solder joint includes, in sequence, a scanned image acquisition module, a grayscale conversion module, a ROI segmentation module, an image positioning module, a solder joint rectangular region division module, a grayscale calculation module, and a ratio calculation module; wherein:

[0026] The scanning image acquisition module is used to acquire the ultrasonic phased array C-scan image of the workpiece to be inspected;

[0027] The grayscale conversion module is used to convert the ultrasonic phased array C-scan image into a grayscale image.

[0028] The ROI segmentation module is used to segment the grayscale image into ROI regions to obtain ROI region images;

[0029] The image positioning module is used to locate the background area and the welding area of ​​the workpiece to be inspected on the ROI area image.

[0030] The weld point rectangular region division module is used to divide the welding area into several weld point rectangular regions according to the position of the weld points on the workpiece to be inspected.

[0031] The grayscale calculation module is used to obtain the average grayscale of the rectangular area of ​​the solder joint and the average grayscale of the background area.

[0032] The ratio calculation module is used to obtain the acoustic reflectivity of the weld point of the workpiece to be inspected based on the average grayscale of the rectangular area of ​​the weld point and the average grayscale of the background area.

[0033] A storage medium storing a computer program, which, when executed by a processor, implements the steps of the aforementioned method for extracting the acoustic reflectivity of a power battery busbar solder joint.

[0034] A computer device includes a storage medium, a processor, and a computer program stored in the storage medium and executable by the processor, wherein the computer program, when executed by the processor, implements the steps of the aforementioned method for extracting the acoustic reflectivity of a power battery busbar solder joint. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating the steps of a method for extracting the acoustic reflectivity of a power battery busbar solder joint according to an embodiment of the present invention.

[0036] Figure 2 This is an example of a C-scan image of an ultrasonic phased array in an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of sound wave reflection in dissimilar metals in an embodiment of the present invention;

[0038] Figure 4 This is an example of a ROI diagram after segmentation of an ultrasonic phased array C-scan image in an embodiment of the present invention;

[0039] Figure 5 This is an example of a schematic diagram showing the location of the welding area in an embodiment of the present invention;

[0040] Figure 6 This is a reflectivity matrix formed by extracting the acoustic reflectivity of the rectangular region of each solder joint in this embodiment of the invention;

[0041] Figure 7 This is a schematic diagram of an acoustic reflectivity extraction system for a power battery busbar solder joint, provided as an embodiment of the present invention. Detailed Implementation

[0042] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent.

[0043] It should be understood that the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0044] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0045] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0046] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. The invention will be further described below with reference to the accompanying drawings and embodiments.

[0047] To address the limitations of existing technologies, this embodiment provides a technical solution. The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0048] Example 1

[0049] Please refer to Figure 1 A method for extracting the acoustic reflectivity of a power battery busbar solder joint includes the following steps:

[0050] S1, acquire the ultrasonic phased array C-scan image of the workpiece to be inspected;

[0051] S2, convert the ultrasonic phased array C-scan image into a grayscale image;

[0052] S3, Perform ROI region segmentation on the grayscale image to obtain ROI region images;

[0053] S4, Locate the background area and the welding area of ​​the workpiece to be inspected on the ROI area image;

[0054] S5, Based on the location of the weld points on the workpiece to be inspected, the welding area is divided into several rectangular weld point areas;

[0055] S6, obtain the average grayscale of the rectangular area of ​​the solder joint and the average grayscale of the background area;

[0056] S7. Obtain the acoustic reflectivity of the weld point of the workpiece to be inspected based on the average grayscale of the rectangular area of ​​the weld point and the average grayscale of the background area.

[0057] Compared to existing technologies, this invention converts the grayscale information of ultrasonic phased array C-scan images into acoustic reflectivity, which is closely related to the defect characteristics of the workpiece under test. This can be used for the detection and evaluation of internal defects in the workpiece under test. The acoustic reflectivity distribution calculated using this method can also serve as one of the bases for locating the welding area and can be further converted into other relevant evaluation indicators, thus improving the accuracy of detection. It is particularly suitable for phased array ultrasonic imaging to detect internal defects in the welding area of ​​workpieces such as arc welding and ultrasonic welding, and to evaluate relevant indicators such as effective weld points and bonding areas.

[0058] Specifically, in this embodiment, the gray level of the image 0-255 corresponds to a reflectance of 0%-100%.

[0059] The ultrasonic phased array C-scan image can be obtained by scanning the workpiece under test with an ultrasonic phased array probe and imaging it through an ultrasonic board, thus obtaining an ultrasonic phased array C-scan image of the busbar workpiece of a new energy vehicle battery. Figure 2 As shown, the image is read into the integrated environment of Visual Studio, QT, and OpenCV libraries, and the image processing is implemented using C++ as the main programming language.

[0060] More specifically, the imaging of the welding area is a superposition of multiple interface reflected waves. In this embodiment, the acoustic reflectivity of the welding layer is extracted by converting the grayscale values ​​of the image. The specific idea or principle is as follows:

[0061] Please see Figure 3 Let the amplitude of the ultrasonic wave incident on the copper sheet be I0'. I0' propagates through the copper material to the second reflection interface and can be further divided into a reflected wave portion I2 and a transmitted wave portion I3, i.e.

[0062] I0' = I2 + I3

[0063] The reflected wave I2 echoes back to the first interface and splits again into reflected wave I. 21 and transmitted wave I 22 .

[0064] I2=I 21 +I 22

[0065] Let the acoustic wave reflectivity of the second interface to be determined be α, then:

[0066] I2=I0'·α

[0067] Let the transmittance of the acoustic wave reflected from the second interface to the first interface be β, then:

[0068] I 21 =I2·β

[0069] During the ultrasound scan, the amplitude of the reflected wave received by the probe is I. 21 The ultrasonic reflectance γ is obtained as follows:

[0070]

[0071] Let the average gray level of the welding area be g. w g w The conversion relationship with γ is as follows:

[0072] g w =γ·255

[0073] The reflection at the second interface from the non-welded area is total internal reflection, i.e., α = 1, therefore the reflectivity γ of the non-welded area is... b for:

[0074]

[0075] Let the average gray level of the non-welded area be g. b g b The conversion relationship with γ is as follows:

[0076] g b =γ b ·255

[0077] The actual reflectivity α of the weld layer can be determined based on γ and γ b Calculated.

[0078]

[0079] The actual reflectivity α of the welding interface can be obtained from the above formula. i，j i and j represent the current rectangular area of ​​the weld point located in the i-th row and j-th column of the welding area, respectively, and the gray level g of the welding area. wi,j gray level g in non-welded area b The conversion relationship.

[0080]

[0081] The final solder joint WED was obtained. i,j Actual reflectivity α i , .

[0082] In a preferred embodiment, in step S2, channel detection is first performed on the ultrasonic phased array C-scan image:

[0083] If the ultrasound phased array C-scan image is a three-channel image, then the library function is used to convert the ultrasound phased array C-scan image into a grayscale image; if the ultrasound phased array C-scan image is a single-channel image, then no conversion is required, and step S3 is executed directly.

[0084] In a preferred embodiment, in step S3, after locating the welded area (WED) of the workpiece to be inspected, the area of ​​the ROI region image excluding the welded area is used as the background region, such as... Figure 4 As shown:

[0085] ROI = WED ∪ BGD;

[0086] In a preferred embodiment, in step S3, a fast neighborhood search algorithm is used to locate the welding area WED of the workpiece to be inspected.

[0087] In a preferred embodiment, the size of the rectangular area of ​​the weld point is calculated based on the measurement results obtained from the actual welding area of ​​the workpiece to be inspected and the resolution of the ultrasonic phased array C-scan image; in the rectangular area of ​​the weld point, the size of the weld point is the tooth shape size of the welding head.

[0088] After precise positioning, the welding area is obtained. The welding area is then divided into several rectangular regions based on the actual tooth-shaped weld points. The welding area is as follows: Figure 5 The arrow points to the box shown.

[0089] In step S6, the WED of the rectangular area of ​​each solder joint is calculated. i,j Average gray level g wi,j If the welding head has 35 toothed welding points, then i = 0, 1, 2, 3...4, j = 0, 1, 2, 3...6.

[0090] WED = WED 0,0 ∪WED 0,1 ∪......WED 4,6 ;

[0091] In a preferred embodiment, in step S6, the ratio obtained by dividing the average gray level of the rectangular area of ​​the weld point by the average gray level of the background area is used as the acoustic reflectivity of the weld point of the workpiece to be inspected.

[0092] In a preferred embodiment, in step S6, the acoustic reflectivity α of the weld point on the workpiece to be inspected is obtained using the following formula:

[0093]

[0094] Among them, g w g represents the average grayscale value of the rectangular area of ​​the solder joint. b This represents the average gray level of the background area.

[0095] Specifically, WED is used for each solder joint rectangular area. i,jAverage gray level g wi,j Divide by the average gray level g of the background area BGD b This allows us to obtain the actual reflectivity of the rectangular region of each solder joint, and store the corresponding reflectivity α[i][j] into a matrix, such as... Figure 6 As shown:

[0096]

[0097] Example 2

[0098] Please see Figure 7 A system for extracting the acoustic reflectivity of a power battery busbar solder joint includes, in sequence, a scanning image acquisition module 1, a grayscale conversion module 2, a ROI segmentation module 3, an image positioning module 4, a solder joint rectangular region division module 5, a grayscale calculation module 6, and a ratio calculation module 7; wherein:

[0099] The scanning image acquisition module 1 is used to acquire the ultrasonic phased array C-scan image of the workpiece to be inspected;

[0100] The grayscale conversion module 2 is used to convert the ultrasonic phased array C-scan image into a grayscale image.

[0101] The ROI segmentation module 3 is used to segment the grayscale image into ROI regions to obtain ROI region images.

[0102] The image positioning module 4 is used to locate the background area and the welding area of ​​the workpiece to be inspected on the ROI area image.

[0103] The weld point rectangular area division module 5 is used to divide the welding area into several weld point rectangular areas according to the position of the weld points on the workpiece to be inspected.

[0104] The grayscale calculation module 6 is used to obtain the average grayscale of the rectangular area of ​​the solder joint and the average grayscale of the background area.

[0105] The ratio calculation module 7 is used to obtain the acoustic reflectivity of the weld point of the workpiece to be inspected based on the average gray level of the rectangular area of ​​the weld point and the average gray level of the background area.

[0106] Example 3

[0107] A storage medium storing a computer program, which, when executed by a processor, implements the steps of the method for extracting the acoustic reflectivity of a power battery busbar solder joint as described in Example 1.

[0108] Example 4

[0109] A computer device includes a storage medium, a processor, and a computer program stored in the storage medium and executable by the processor. When executed by the processor, the computer program implements the steps of the method for extracting the acoustic reflectivity of a power battery busbar solder joint as described in Embodiment 1.

[0110] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for extracting acoustic reflectivity of a power battery busbar weld, characterized in that, Includes the following steps: S1, acquire the ultrasonic phased array C-scan image of the workpiece to be inspected; S2, convert the ultrasonic phased array C-scan image into a grayscale image; S3, perform ROI region segmentation on the grayscale image to obtain an ROI region image; after locating the welding area WED of the workpiece to be inspected, use the area of ​​the ROI region image other than the welding area as the background area. S4, Locate the background area and the welding area of ​​the workpiece to be inspected on the ROI area image; S5, Based on the location of the weld points on the workpiece to be inspected, the welding area is divided into several rectangular weld point areas; S6, obtaining the average gray scale of the solder joint rectangular region and the average gray scale of the background region, and taking the ratio of the average gray scale of the solder joint rectangular region divided by the average gray scale of the background region as the acoustic reflectivity of the solder joint of the workpiece to be detected; specifically, the acoustic reflectivity of the solder joint of the workpiece to be detected is obtained by the following formula α : ； in, This represents the average grayscale value of the rectangular area of ​​the solder joint. This represents the average gray level of the background area; The background area corresponds to the region where ultrasonic waves undergo total reflection at the non-welding interface of the workpiece to be inspected, and the acoustic wave reflectance corresponding to each pixel in the background area is 1.

2. The method for extracting the acoustic reflectivity of the busbar solder joint of a power battery according to claim 1, characterized in that, In step S2, channel detection is first performed on the ultrasonic phased array C-scan image: If the ultrasound phased array C-scan image is a three-channel image, then the library function is used to convert the ultrasound phased array C-scan image into a grayscale image; if the ultrasound phased array C-scan image is a single-channel image, then no conversion is required, and step S3 is executed directly.

3. The method for extracting the acoustic reflectivity of the busbar solder joints of a power battery according to claim 1, characterized in that, In step S3, a fast neighborhood search algorithm is used to locate the welding area WED of the workpiece to be inspected.

4. The method for extracting the acoustic reflectivity of the busbar solder joint of a power battery according to claim 1, characterized in that, The size of the rectangular area of ​​the weld point is calculated based on the measurement results obtained from the actual welding area of ​​the workpiece to be inspected and the resolution of the ultrasonic phased array C-scan image; in the rectangular area of ​​the weld point, the size of the weld point is the tooth size of the welding head.

5. A system for extracting the acoustic reflectivity of a power battery busbar solder joint, characterized in that, The method for extracting acoustic reflectance as described in any one of claims 1 to 4 comprises, in sequence, a scanned image acquisition module (1), a grayscale conversion module (2), a ROI segmentation module (3), an image positioning module (4), a solder joint rectangular region division module (5), a grayscale calculation module (6), and a ratio calculation module (7); wherein: The scanning image acquisition module (1) is used to acquire the ultrasonic phased array C-scan image of the workpiece to be inspected; The grayscale conversion module (2) is used to convert the ultrasonic phased array C-scan image into a grayscale image; The ROI segmentation module (3) is used to segment the grayscale image into ROI regions to obtain ROI region images; The image positioning module (4) is used to locate the background area and the welding area of ​​the workpiece to be inspected on the ROI area image. The weld point rectangular area division module (5) is used to divide the welding area into several weld point rectangular areas according to the position of the weld point on the workpiece to be inspected. The grayscale calculation module (6) is used to obtain the average grayscale of the rectangular area of ​​the solder joint and the average grayscale of the background area; The ratio calculation module (7) is used to obtain the acoustic reflectivity of the weld point of the workpiece to be inspected based on the average gray level of the rectangular area of ​​the weld point and the average gray level of the background area.

6. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the method for extracting the acoustic reflectivity of the power battery busbar solder joint as described in any one of claims 1 to 4.

7. A computer device, characterized in that: The device includes a storage medium, a processor, and a computer program stored in the storage medium and executable by the processor, wherein the computer program, when executed by the processor, implements the steps of the method for extracting the acoustic reflectivity of the power battery busbar solder joint as described in any one of claims 1 to 4.

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