Laser processing technology, because of its own technical advantages, plays an increasingly important role in the lithium battery industry, such as laser welding of cores and modules, pole material cutting, marking and so on. This paper mainly introduces the lithium battery laser welding machine automated production line in the material transfer system, adaptive system, visual positioning system, MES manufacturing execution management and other key technologies.
Lithium batteries due to its high energy density, high voltage, environmental protection, long life and can be quickly recharged and other advantages, favored by the 3C digital, power tools and other industries, the new energy automotive industry contribution is particularly prominent. As the core component of new energy vehicles, its power supply performance, stability, safety is an important aspect of the performance of new energy vehicles, power battery welding quality plays a decisive role in the performance of the power battery, which in turn determines the performance of the vehicle. Laser processing technology because of its own technical advantages, in the lithium battery industry, such as the core and module laser welding, pole piece material cutting, marking and so on play an increasingly important role!
1. The application of laser welding in the manufacture of lithium batteries
Laser welding is a laser beam as a source of energy, the use of focusing devices so that the laser aggregated into a high power density beam irradiated on the surface of the workpiece for heating, in the heat conduction of the metal material under the action of the internal dissolution of the material to form a specific soluble pool. Laser welding is a new type of welding method, currently in the high-speed development stage. When laser welding, the heat-affected zone of the workpiece is small; small weld joints, high precision welding dimensions; the welding method is non-contact welding, no need to add external force, small product deformation, high welding quality, high efficiency, easy to realize automated production.
From the manufacturing of lithium battery cells to battery PACK into a group, welding is a very important manufacturing process, lithium battery conductivity, strength, airtightness, metal fatigue and corrosion resistance, is a typical battery welding quality evaluation standards. The choice of welding method and welding process will directly affect the cost of the battery, quality, safety and consistency of the battery.
Secondly, laser welding can be precisely controlled, with a small focused spot and high-precision positioning, which, together with the robotic arm, is easy to automate, increase welding efficiency, reduce man-hours, and lower costs. In addition, laser welding of thin plates or fine-diameter wires will not be plagued by melting back, as is the case with arc welding.
The structure of the battery usually contains a variety of materials such as steel, aluminum, copper, nickel, etc. These metals may be made into electrodes, wires, or shells, therefore, whether it is a material or a variety of materials between the welding, are put forward to the welding process of high requirements. The advantage of the laser welding process lies in the wide range of materials that can be welded and the ability to weld different materials.
2. Laser welding in the lithium battery PACK production line in the key technology
Lithium battery laser welding machine battery module automation production line, generally including the core loading, scanning, testing, cleaning, sorting, module stacking, stacking detection, and module welding, welding detection, module discharging and other processes, the material transfer system, adaptive system, vision positioning system, MES manufacturing execution management, etc., is the key technology in the entire production line, but also to adapt to the small batch multi-species production pattern of the important Technical support.
1) Material Transfer System
From core loading to final module unloading, the entire material transfer is completed through the material transfer system, which can also flexibly expand the working stations according to the adjustment needs of the process, and the transfer between different stations does not require human operation, and the module positioning plate comes with a product size adjustment mechanism, which can adapt to the clamping of modules of different sizes, and it is very suitable for small-lot, multi-variety production needs.
2) Adaptive system
In the production process of battery module, soft pack, square and cylindrical are the most common types of incoming batteries, and after stacking different sizes of batteries into different sizes of modules, every process needs to be adapted to the adaptive system to ensure the linkage of the whole line beat, especially in the welding process, which is only adapted to the different sizes of modules in order to complete the module PACK process.
Adaptive system adopts multi-axis combination linkage to implement the positional positioning in the product processing area, without any form of incoming material restriction, to complete the welding work and transfer to the next process.
3）Visual Positioning System
Core welding surface cleaning, module marking, converging piece welding is usually completed by laser processing, battery module assembly, often with large dimensional tolerances, it is difficult to achieve the laser processing on the gap position size requirements, resulting in a sharp decline in processing quality. The introduction of visual positioning system can meet the demand for accurate positioning, the accuracy can reach ± 0.05mm, through the vision of the photo data acquisition, and feed back to the control system to material deviation, thus realizing the processing position of high-precision positioning.
4）MES Manufacturing Execution Management System
MES manufacturing execution management system has an open development platform, can be based on the underlying platform of the system quickly and agilely according to user needs to complete the implementation of the MES project development, manual only according to the MES parameter instructions to guide the work, and through the form of charts and comprehensive statistics and analysis of the existing production setup information to improve. From core loading to final module discharging, the parameters, data, and other incoming information of each process can be quickly queried and timely analyzed and processed through the MES system, which really makes the process controllable and efficient. Laser welding process data package is directly integrated into the MES system to facilitate the user to call and switch, the whole set of MES system can be directly to the production line into a quasi-unmanned production workshop, manual only in the periphery of the material replenishment to improve safety. With the reserved industrial communication interface, users can not only realize remote monitoring and management, but also effectively docking with enterprise ERP, truly realizing intelligent and informative factory.
