With the improvement of people's living standards, the problem of high emission and high pollution of traditional fuel vehicles has attracted more and more attention, which has brought a broad opportunity for new energy vehicles.
In the manufacturing process of lithium battery or battery pack of new energy vehicles, more than 20 processes need to realize conductive connection or sealing by welding. The quality of welding plays a vital role in the safety performance of the whole vehicle.
1. Battery cap welding
18650 battery is a lithium-ion cylindrical battery, which is mainly used in Tesla new energy vehicles. As the electrode of the battery, the battery cap shall be welded with the battery substrate. The 0.3mm stainless steel cap shall be welded on 0.5 aluminum. The weld bead shall be white and bright, and the welding tension value shall be more than 200N.
Using MAX CW fiber laser for swing welding, compared with YAG spot welding, the welding firmness and sealing are better, the weld bead is larger, the contact surface between the cap and the battery substrate is larger, the weld bead is bright white, and the welding tension value reaches more than 255n.
2. Welding of positive and negative poles of power battery
For square batteries, each battery needs to be connected in series and parallel through positive and negative electrode columns to form a battery module unit, so each battery needs to be welded with a pair of positive and negative electrode columns. The negative pole is made of copper and the positive pole is made of aluminum. The weld bead is required to be round, non blackening, 1.2mm wide and 0.5mm deep, and firmly welded.
The battery pole is made of copper and aluminum, which is a high reflection material. It requires good laser beam quality and high energy density in order to be fully welded and firmly welded. Using MAX laser fiber laser for swing welding, the contact area is larger, the positive and negative surfaces of the welded samples basically maintain the color of the substrate body, the finish is bright, the pole column is completely welded, and the welding with the battery unit is more firm.
3. Copper pin welding of motor stator
The power source of new energy vehicles has changed from the engine of traditional fuel vehicles to an electric motor, which is mainly composed of stator and rotor. The copper pins inside the stator need to be welded together. It is required that the melting width is small, the melting depth is greater than 3mm, and the test shear force is greater than 400N. The paint layer cannot be burned during welding.
The stator pin is made of red copper and has high requirements for penetration and shear force. Using high beam quality continuous fiber laser welding can ensure that the deep penetration can be achieved under a sufficiently small fusion width, ensure sufficient firmness, and ensure that the stator pins are continuously opened during the high-speed rotation of the motor. It can be seen from the effect of MAX laser fiber laser welding motor stator copper pin that its melting width, melting depth, shear force and welding surface appearance meet the welding requirements of new energy vehicles.
