Introduction of Kunshan Joule laser: application of laser welding in power battery industry

Electric vehicles are widely used at home and abroad for their energy saving and environmental protection, low cost, fast acceleration and low noise, and have a very broad market prospect. According to the 13th five year plan, by 2020, the number of electric vehicles in China will reach 5 million, and the annual output will reach 2 million. According to the prediction of China Battery 100 Association, the number of electric vehicles sold in 2016 will not exceed 700000; The next four years to 2020 will be the key years for the rapid development of electric vehicles in China.

The key technologies for the future development of electric vehicles are the safety, cost and energy storage capacity of power batteries. The manufacturing process of power battery is complex and the safety requirement is high; Laser welding is one of the key technologies in the manufacturing process; The laser welding process of power battery includes battery soft connection welding, top cover welding, sealing nail welding, module and pack welding. There are many laser welding parts for power battery, and the requirements of reliability and safety are high, which puts forward higher requirements for laser welding equipment.

1. Laser welding system of sealing nail

Laser sealing nail welding equipment has the advantages of compact station structure, small space occupation, high production efficiency, and stable welding effect (beautiful welding appearance, good consistency, and stable process). The welding capacity of the equipment ranges from 4ppm to 20ppm, and the yield can reach more than 99.8%. The front end of the equipment is cleaned by laser, with good cleaning effect and no impurity residue.

In addition, the sealing nail of the sealing nail welding equipment adopts the vibration plate to automatically feed, automatically detect the front and back sides of the sealing nail, and can monitor the welding effect in real time during welding; At the same time, it uses the way of coaxial blowing protective gas to protect the welding products, and detects the welding effect after welding. The welding seam is smooth without false welding, pinhole, burst point and other phenomena; The equipment adopts the latest developed fixture mechanism, which has the advantages of anti scratch products, dustproof, easy to clean, easy to change and so on.

2. Soft link laser welding system

There are two types of soft connection welding table equipment: on-line and off-line. It uses a small space to achieve a high degree of integration of multiple functions, which can greatly save the space of the plant. The power battery soft connection automatic laser welding production line includes feeding, code engraving, laser welding, laser cleaning, quality inspection after welding, t folding, film sticking, blanking and other processes. All of them adopt the fully automatic production process, which is simple and coherent, with high efficiency and good quality.

The production capacity of flexible connection welding equipment ranges from 4ppm to 12ppm, the yield rate of equipment can reach more than 99.8%, and the welding speed can reach up to 200mm / s. The laminating mechanism is independently developed by lianwin, and the fixture has developed to the sixth generation (the fixture has the obvious advantages of dust-proof, anti card, anti scratch products, self-cleaning, easy replacement, etc.). This welding station has become a mature and stable automation equipment of lianwin. At present, our company has invested in the research and development of 20ppm production capacity of automatic welding line.

3. Power battery top cover welding system

Top welding and side welding are two main welding methods for power battery top cover. For these two welding methods, lianwin laser has corresponding mature and reliable automatic welding system.

The full-automatic laser welding production line for top welding of power battery cover includes automatic feeding, benchmark loading, locking, protective cover placing, laser welding, post welding inspection (appearance and edge wrapping), unlocking, blanking, clamp blowing cleaning and other processes, all of which adopt full-automatic production process, with simple and coherent production process, high efficiency and excellent rate. The press mounting technology of this equipment is an independent innovative design, which can effectively press the top cover and the battery shell without damaging the battery, making the top cover and the shell perfectly match, and making necessary preparations for the subsequent welding of excellent products. This equipment is the first in the industry, which can be directly full welded without pre spot welding, greatly improving the production efficiency of the automatic line and reducing the cost. The full welding station adopts special process for real-time monitoring, so as to avoid affecting the welding effect or producing unnecessary ng products due to the product height difference. The fixture of the welding equipment for the top cover is also under constant research and development and updating. The fixture mechanism used in this equipment has the advantages of anti scratch, automatic up and down protection of the cover plate, self-cleaning and easy replacement.

4. Pack welding system for battery module

In the development of module pack welding equipment, lianwin focuses on the research and development of laser cleaning process before welding and galvanometer welding coaxial blowing protective gas system, and has achieved good results. The module welding equipment is a fully automatic line. Before welding, the battery pole and connection are respectively cleaned by laser to remove the oxide layer and organic matter on the product surface, which can effectively improve the welding quality and product over-current ability. Galvanometer welding coaxial blowing protective gas system can greatly improve the welding efficiency and ensure the welding quality. At the same time, the welding equipment can automatically detect the welding appearance. At the same time, the self-developed smoking mechanism can effectively prevent welding slag and debris from falling on the surface of the battery and prevent the occurrence of short circuit. The welding quality of module welding equipment is good, and the yield rate can reach more than 99.5%.