[Application Case] Busbar Pre weld&Post weld Inspection for Lithium Battery Module Lines

Project background

In the power battery pack, the battery cells are the core component of the battery pack.

The voltage of a single lithium battery cell is relatively small, which can only drive small products and cannot drive electric vehicles. Therefore, it is necessary to further expand the voltage and capacity of multiple battery cells through series and parallel connection to form a lithium battery pack for electric vehicle power use.

The power battery pack is the most critical component of the entire vehicle. Generally, if the battery pack is damaged, subsequent replacement and maintenance will also require a certain amount of manpower and financial resources. Therefore, before leaving the factory, it is not only necessary to strictly control the production process steps of the module line, but also the quality inspection and module assembly before leaving the factory are particularly important.

During the assembly process of the power battery module line, an important step is the module busbar welding, which involves welding different battery cells in series and parallel through connecting paddles. In order to ensure welding quality and prevent defective welding products from flowing into the next process, it is necessary to perform positioning and addressing before welding, in order to control the gap between the paddles and electrodes, and to inspect the appearance of the weld seam after welding to eliminate defective products.

In the past, Busbar detection was usually mainly based on 2D detection technology, but the traditional 2D machine detection imaging effect fluctuated greatly, resulting in high reflection in the image and inability to accurately extract the contour of the weld seam. Therefore, Huahan Weiye added 3D high-precision visual detection technology to the visual detection scheme, which can measure the size and detect defects of the module Busbar, ensuring the quality of the module.

Busbar pre weld/post weld quality inspection

1. Testing items

Pre welding inspection: The gap between the connecting piece and the pole should be controlled within a tolerance of 0~0.2mm;

Post weld inspection: explosion points, dents, protrusions, weld penetration, cracks/fissures in the weld seam, and dimensional deviation of the weld seam.

2. Solution

Software: Huahan HyperShape 3D detection software/2D detection software

Hardware: 3D line scanning laser profilometer;

Detection method: Double camera reverse installation to solve the problem of obstructed field of view.

（Lighting diagram）

3. Test results

1) The scanning speed is 150mm/s, the dynamic repeatability of pre weld gap detection is 0.02mm, and the accuracy of post weld seam length and width measurement is 0.1mm. The speed is fast and the accuracy is high;

2) Flexible solution, 2D can accurately measure size, 3D can stably detect welding defects such as bursting points, dents, and weld penetration, with a leakage rate of 0% and a misjudgment rate of<0.1%.

（Presentation of renderings）

Project Summary

With the development of industry, the application of machine vision in industrial production is becoming increasingly widespread. Moreover, with the continuous upgrading and transformation of technological level, the requirements for detection will also become higher. Therefore, solutions need to be continuously optimized and upgraded according to market requirements.

At present, in the field of machine vision, 2D detection technology has become very proficient, and the application of high-precision 3D visual detection in industrial detection is becoming increasingly widespread. Since its establishment, Huahan Weiye has focused on the research and innovation of machine vision technology. Its self-developed 3D detection software can simultaneously achieve high contour capture, 3D point cloud data collection, and 3D data measurement functions. It is widely used in high-precision, high-speed, online 3D positioning, measurement and other scenarios. Its built-in self-developed algorithm has successfully filled the gap in China and currently ranks among the top tier in the country.

The company provides machine vision components and solutions, which can be customized flexibly. Currently, the company has a delivery team of over 100 people and has practical and mature deployment experience in multiple projects, which can meet strict project time requirements. To ensure product stability and reliability, the company can provide 7 * 24-hour after-sales service. With a pragmatic service attitude and innovative research and development spirit, the company has won high recognition from customers and has a good reputation in the industry.