The laser emission wavelength is 1064 nm, and the focusing head has a focal length of 100 mm. By changing the pulse energy, pulse length and focus position, a series of optimization tests were carried out on the overlap and edge welding configuration. Experiments were also performed by coating the top surface of Cu with graphite or using a 0.15 mm Ni foil on the top of the Cu plate to enhance the coupling and activation of the keyhole welding mode. Ni forms a favorable alloy with Cu and Al and is therefore compatible with both materials. Using a pulse energy of 11 J and a pulse width of 5 ms can achieve good welding results that combine 0.13 mm thick Cu with 2.0 mm thick Al
Defocus the laser beam so that the focus is 1.5 mm below the surface of the top sheet. Use defocus to increase the size of the dots, thereby increasing the width of the welding interface. Weld penetration in aluminum> 1.0 mm. This may be due to the need for high pulse energy to melt it through the Cu sheet into Al. For edge spot welding, place the copper plate on top of the aluminum plate, and then aim the laser beam at the lower aluminum surface about 0.2 mm from the edge of the copper plate
Due to the limited space between the processing head and the workpiece, the optical system was first simulated using commercial optical design software. Component interference detection analysis is carried out to ensure that the optical path does not have any back reflection or undesired scattered radiation. In addition, the software has been updated to tailor more efficient data collection to the modified optical settings.
It can be used to seal battery cans after verification. A comprehensive study was conducted in which different types of process and part defects were simulated, which are usually found in industrial equipment. Table 1 shows the types and causes of defects investigated and their effect on monitoring conditions (melt pool size). It can be seen that for each type of defect, the change pattern of the width and length of the molten pool is different. This allows specific defects to be associated with specific signal patterns, so it can provide information to distinguish various defects that occur simultaneously. Since the sealing of the battery tank needs to meet the strict requirements on tightness and welding strength, the real-time process monitoring system can perform quality inspection on 100% of the products without interrupting the production cycle.
Summary and conclusion The laser processing capabilities suitable for the assembly and packaging of batteries and fuel cells have been discussed. Laser welding of similar and dissimilar material combinations shows the application fields and advantages of this technology