3. Welding mode analysis:

1. Pulse mode welding

Commonly used pulse waveforms of pulse lasers include square waves, spike waves, double-peak waves, etc. Since the reflectivity of the aluminum alloy surface to light is too high, an appropriate welding waveform should be selected during welding. When a high-intensity laser beam is incident on the material surface, 60% to 98% of the laser energy will be lost due to reflection on the metal surface, and the reflectivity changes with the temperature of the object surface. Generally, when welding aluminum alloys, it is best to choose sharp waves and double-peak waves. The pulse width of the slow-down part behind these two welding waveforms is longer, which can effectively reduce the occurrence of pores and cracks.

Due to the high reflectivity of aluminum alloy to laser, in order to prevent the laser beam from being vertically incident and causing vertical reflection and damaging the laser focusing mirror, the welding head is usually deflected at a certain angle during the welding process. The diameter of the solder joint and the diameter of the effective joint surface increase with the increase of the laser tilt angle. When the laser tilt angle is 40°, the largest solder joint and effective joint surface are obtained. The welding spot penetration and effective penetration decrease with the laser tilt angle. When the laser tilt angle is greater than 60°, the effective welding penetration drops to zero. Therefore, tilting the welding joint to a certain angle can appropriately increase the penetration depth and width of the weld. In addition, during welding, 65% of the laser welding spot cover plate and 35% of the shell need to be welded with the weld seam as the boundary, which can effectively reduce explosions caused by cover closing problems.

2. Continuous mode welding

Because the heating process of continuous laser welding is not like pulse sudden cooling and heating, the tendency of cracks during welding is not very obvious. In order to improve the quality of the weld, continuous laser welding is used. The surface of the weld is smooth and uniform, without spatter, no defects, and there is no internal weld. Cracks found. In terms of aluminum alloy welding, continuous laser has obvious advantages: compared with traditional welding methods, it has high production efficiency and does not require wire filling; compared with pulse laser welding, it can solve the defects caused after welding, such as cracks, pores, and spatter. etc., to ensure that the aluminum alloy has good mechanical properties after welding; there will be no dents after welding, and the amount of polishing and grinding will be reduced, saving production costs. However, because the continuous laser spot is smaller, the assembly accuracy of the workpiece is required to be higher.

During the power battery welding process, welding process technicians will select the appropriate laser and welding process parameters based on the battery material, shape, thickness, tension requirements, etc., including welding speed, waveform, peak value, welding head tilt angle, etc. to set reasonable welding Process parameters to ensure that the final welding effect meets the requirements of power battery manufacturers.

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  4. Square battery welding

In the welding process of square batteries, the most important process is the sealing of the shell cover. The sealing method of the square battery shell is generally to have a rectangular cover plate on the top of the battery with a positive input terminal, and the cover plate is inserted into the shell. flush with the mouth, and then use laser to weld the rectangular gap between the cover plate and the shell with pulse or continuous laser welding to seal it.

The welding methods of square batteries are mainly divided into side welding and top welding. The main benefit of side welding is that it has less impact on the inside of the battery core and spatter will not easily enter the inside of the shell cover. Since bulges may occur after welding, which will have a slight impact on the assembly of subsequent processes, the side welding process has extremely high requirements on the stability of the laser and the cleanliness of the material. Since the top welding process is welded on one surface, the requirements for the integration of welding equipment are relatively low.

At present, the vertical welding method of power batteries is a widely favored welding method in the industry. Vertical welding only requires one closing node, which can greatly reduce the risk of side leakage of four closing nodes in side welding, and is conducive to mass production. Shenzhen SHINHOP Laser Equipment Co., Ltd.'s "high-speed battery case laser vertical welding equipment" has achieved a welding yield rate of more than 99.5% and a production efficiency of 12PPM.

  5. Battery PACK process:

1.Battery PACK

The production process of applied battery packs formed by adding protection circuits, casings, and outputs to battery cells is called PACK. Battery PACK is an important process to realize the application of batteries in different fields. With the continuous development of the PACK process, the connection methods have also been continuously improved. From the initial soldering to the later resistance welding, laser welding has become the current PACK process due to its advantages of welding precision, reliability and high degree of automation. The most extensive connection method, and intelligent automation equipment equipped with laser welding technology has become a high-end manufacturing equipment for groups of prismatic, cylindrical, pouch, 18650 and other different types of battery packs.

2. Development trends of intelligent equipment

The development of the new energy automobile industry has not finalized and standardized the specifications and standards of the power batteries and battery modules used. Many problems of incompatibility of specification systems have arisen. The current process flow and manual operations have restricted the production rhythm of the enterprise. and efficiency, thereby failing to effectively improve product quality and production capacity. Therefore, it is very necessary to improve the automation level of power battery module assembly. Nowadays, the intelligent solution of "whole line equipment + robot + software control" must not only solve the compatibility, whole line rhythm and efficiency issues that users are focused on, but also solve the problems of users' battery PACK orders with small batches and multiple specifications. .

Management software. The entire MES system directly turns the production line into a quasi-unmanned production workshop, and workers only need to replenish materials outside the line, which not only improves safety but also reduces human intervention. In the welding process, only the laser welding process data needs to be integrated into the MES management software system to facilitate users to directly call and switch. From battery cells to PACK groups, the parameters, data and other incoming material information of each process can be quickly queried and analyzed and processed in a timely manner through the MES system. It is necessary to achieve process controllability and effectively ensure production efficiency. Users It also realizes remote monitoring and management through reserved industrial communication interfaces, fully reflecting the characteristics of intelligent automated manufacturing. Products equipped with laser solutions have developed towards the trend of high intelligence and high automation.

6. Trustworthy battery manufacturing laser equipment