CN-121994799-A - Mylar film hot-melt wire drawing detection system and method suitable for lithium battery production

CN121994799ACN 121994799 ACN121994799 ACN 121994799ACN-121994799-A

Abstract

The invention particularly relates to a Mylar film hot-melt wire drawing detection system and method suitable for lithium battery production. The system comprises an image acquisition module used for acquiring surface images of the lithium battery cell coated with the Mylar film, an image processing module used for controlling the first shooting component and the second shooting component to acquire images respectively and identifying outline features positioned at the edge of a view field and corresponding to the side opposite to the other shooting component in the acquired images, and an analysis and calculation module used for receiving outline feature information uploaded by the image processing module and identifying whether the outline feature information has the protruding features extending to a background area or not. The system does not need to set a high-resolution camera and a complex image processing algorithm, is suitable for various lithium battery production lines, can accurately detect Mylar film hot-melt wire drawing, and improves the yield of lithium battery cells.

Inventors

LONG WENJIE
WEI HONGSHUAI
XU BINGBING
Min Qiangfeng

Assignees

天能新能源(湖州)有限公司

Dates

Publication Date: 20260508
Application Date: 20260112

Claims (10)

1. Mylar film hot-melt wire drawing detection system suitable for lithium cell production, its characterized in that, the system includes: The device comprises an image acquisition module, an illumination assembly, a first image acquisition module, a second image acquisition module and a display module, wherein the image acquisition module is used for acquiring a surface image of a lithium battery cell coated with a Mylar film; The image processing module is connected with the image acquisition module and is used for controlling the first shooting component and the second shooting component to acquire images respectively and identifying outline features positioned at the edge of a view field and corresponding to the opposite side surface of the other shooting component in the acquired images respectively; And the analysis and calculation module is connected with the image processing module and is used for receiving the profile characteristic information uploaded by the image processing module, identifying whether the profile characteristic information has a protrusion characteristic extending to the background area or not, judging that the Mylar film is a hot-melt wire drawing defect if the profile characteristic information has the protrusion characteristic extending to the background area and meeting the preset judgment condition, and generating defect position information.
2. The Mylar film hot-melt wire drawing detection system suitable for lithium battery production, which is disclosed by claim 1, is characterized in that the illumination assembly and the corresponding first shooting assembly or second shooting assembly are integrated into an integral imaging unit, the illumination assembly comprises a plurality of strip-shaped light sources distributed in a surrounding mode, cameras of the first shooting assembly or the second shooting assembly are located in a central area formed by surrounding the strip-shaped light sources, and light rays emitted by the strip-shaped light sources together cover the opposite sides of a lithium battery cell.
3. The Mylar film hot-melt wire drawing detection system suitable for lithium battery production according to claim 2 is characterized in that the first shooting assembly comprises a first camera and a second camera which are arranged oppositely, the lithium battery cell is located between the first camera and the second camera, the image processing module controls the first camera to shoot a first side contour of the lithium battery cell and is used for detecting Mylar film hot-melt wire drawing close to one side of the first camera, and controls the second camera to shoot a second side contour of the lithium battery cell and is used for detecting Mylar film hot-melt wire drawing close to one side of the second camera.
4. The Mylar film hot-melt wire drawing detection system suitable for lithium battery production according to claim 2, wherein at least one group of the first shooting component and the second shooting component comprises at least two sub-cameras which are arranged in parallel along the detected side direction of the lithium battery cell, the fields of view of adjacent sub-cameras have overlapping areas, and the total field of view formed by the at least two sub-cameras together covers the whole length of the side of the lithium battery cell.
5. The Mylar film hot-melt wire drawing detection system suitable for lithium battery production according to claim 2, wherein the illumination assembly further comprises a spherical integral light source, and the spherical integral light source is covered on the periphery of the detection station of the lithium battery cell and is used for providing diffuse reflection illumination and eliminating local reflection interference on the surface of the Mylar film.
6. The Mylar film hot-melt wire drawing detection method suitable for lithium battery production is characterized by comprising the following steps of: the method comprises the steps of controlling a first shooting component and a second shooting component to respectively acquire surface images of a lithium battery cell coated with a Mylar film, wherein an optical axis of the first shooting component and an optical axis of the second shooting component are arranged in a non-parallel manner; identifying outline features positioned at the edge of a view field and corresponding to the opposite side surface of the other shooting component in the images acquired by the first shooting component and the second shooting component respectively; Identifying whether a protruding feature extending to a background area exists in the profile feature information; if the protruding feature extending to the background area exists and the preset judging condition is met, judging that the Mylar film is a hot-melt wire drawing defect, and generating defect position information.
7. The method for detecting the hot-melt wire drawing defect of the Mylar film, which is applicable to the production of lithium batteries, according to claim 6, is characterized in that the step of judging the hot-melt wire drawing defect of the Mylar film specifically comprises the following steps: performing image preprocessing, namely performing RGB channel separation on the acquired surface image of the lithium battery cell, and converting the surface image into a gray image; Recognizing edge characteristic points of a lithium battery cell in a gray level image as positioning references, and selecting an interested region at the junction of a background region of the gray level image and a lithium battery cell body according to the positioning references; feature segmentation is carried out, and a connected region of suspected defects is extracted from the region of interest by adopting a connected region analysis algorithm; judging whether the gray value of the communication area is larger than a gray preset threshold value or not and whether the pixel area of the communication area is larger than an area preset threshold value or not, and judging that the communication area contains Mylar film hot-melt wire drawing defects if the gray value of the communication area is simultaneously satisfied.
8. The Mylar film hot-melt wire drawing detection method suitable for lithium battery production, which is disclosed by claim 7, is characterized in that the step of identifying the edge characteristic points of the lithium battery cells in the gray level image as positioning references is specifically to extract corner points or boundary line intersection points of the lithium battery cells in the gray level image through an edge detection algorithm as the positioning references.
9. The method for detecting the Mylar film hot-melt wire drawing suitable for lithium battery production according to claim 7, wherein the gray preset threshold value is a 90 gray value.
10. The method for detecting the Mylar film hot-melt wire drawing suitable for lithium battery production according to claim 7, wherein the area preset threshold value is 10 pixels.

Description

Mylar film hot-melt wire drawing detection system and method suitable for lithium battery production Technical Field The invention relates to the technical field of lithium battery production, in particular to a Mylar film hot-melting wire drawing detection system and method suitable for lithium battery production. Background In the manufacturing process of the aluminum-shell lithium battery, a layer of polyester polymer insulating film (Mylar film) needs to be wrapped before the bare cell is assembled into the aluminum shell so as to realize insulation protection. The film is typically fixedly sealed by localized hot melt welding. However, as the thermal head completes the weld and lifts off, the molten material may be stretched to form extremely fine, transparent "hot melt strands". If the wire drawing is remained on the surface of the Mylar film, the film clamping explosion point is easily caused by heating or pressing in the subsequent shell and top cover laser welding process, so that serious defects such as battery sealing failure, internal short circuit and the like are caused, and the product is scrapped in batches. Currently, the prior art generally adopts an on-line detection system based on machine vision to automatically check the appearance of a battery. The system can identify conventional defects such as breakage, pollution, poor welding and the like by shooting images of all surfaces of the battery and applying a preset algorithm. For flaws with obvious color contrast or morphological characteristics, the technical scheme has better engineering applicability and detection stability. However, the conventional visual inspection technology has serious insufficient recognition capability for the hot-melt wire drawing. The method is mainly characterized in that firstly, the physical size of the hot-melt wire drawing is tiny, the material is transparent, gray scale or color contrast is hardly generated between the hot-melt wire drawing and a background Mylar film under uniform illumination, imaging signals are extremely weak, secondly, an existing detection camera is usually parallel to a detected surface for shooting, the surface of the Mylar film is usually prone to extending vertically, the projection area of the hot-melt wire drawing on an imaging plane of the camera is further reduced, a characteristic threshold value which can be stably extracted by an existing vision system is difficult to trigger, thirdly, in order to capture the characteristics of the hot-melt wire drawing, the prior art is often dependent on arranging a camera with extremely high resolution and arranging a complex image processing algorithm, the system cost is greatly increased, and strict requirements are put on calculation instantaneity and environmental stability, stable and reliable full-detection coverage are still difficult to realize in an actual production line, and the application range is small. Disclosure of Invention The invention aims to provide a Mylar film hot-melt wire drawing detection system and a Mylar film hot-melt wire drawing detection method suitable for lithium battery production, which can efficiently and accurately detect tiny and transparent Mylar film hot-melt wire drawing and improve the yield of lithium battery cells. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows. In a first aspect, the present invention provides a Mylar film hot-melt wire drawing detection system suitable for lithium battery production, the system comprising: The device comprises an image acquisition module, an illumination assembly, a first image acquisition module, a second image acquisition module and a display module, wherein the image acquisition module is used for acquiring a surface image of a lithium battery cell coated with a Mylar film; The image processing module is connected with the image acquisition module and is used for controlling the first shooting component and the second shooting component to acquire images respectively and identifying outline features positioned at the edge of a view field and corresponding to the opposite side surface of the other shooting component in the acquired images respectively; And the analysis and calculation module is connected with the image processing module and is used for receiving the profile characteristic information uploaded by the image processing module, identifying whether the profile characteristic information has a protrusion characteristic extending to the background area or not, judging that the Mylar film is a hot-melt wire drawing defect if the profile characteristic information has the protrusion characteristic extending to the background area and meeting the preset judgment condition, and generating defect position information. The illumination assembly and the corresponding first shooting assembly or second shooting assembly are integrated into an integral imaging unit, the illumination assembly comprise