Dual-beam laser welding is mainly to solve the problem of laser welding on the adaptability of assembly accuracy and improve the stability of the welding process, suitable for thin plate welding and aluminum alloy welding. This process is not only characterized by large welding depth, high speed and high precision, but also has good applicability to materials that are difficult to be welded by single-beam laser welding. For example, dual-beam laser welding technology in the automotive industry is often used in the welding of galvanized steel, in the welding of unequal thickness plate and thick plate welding are also applied.
Dual-beam laser welding can be performed by optically separating the same laser into two separate beams, or by combining two different types of lasers, CO2 lasers, YAG lasers, and high-power semiconductor lasers, all of which can be combined with each other.
Dual-beam laser welding in the welding process at the same time using two laser beams, beam layout, spacing, the angle of the two beams, focusing position and the energy ratio of the two beams are important parameters. Double beam laser arrangement generally has two kinds of ways: one is along the welding direction is a series of rows and columns, can reduce the cooling speed of the molten pool, reduce the tendency to harden the weld and the generation of porosity; the second is in the weld on both sides of side-by-side rows or cross rows, in order to improve the adaptability of the joint gap.
When two different types of laser beams are used to form a double beam, there are various combinations. For example, a high-quality CO2 laser with a Gaussian distribution of energy is used for the main welding work, supplemented by a semiconductor laser with a rectangular distribution of energy for auxiliary heating. This combination is more economical, the power of the two beams can be independently adjusted for different joint forms, by adjusting the overlap position of the CO2 laser and the semiconductor laser to obtain an adjustable temperature field, which is more suitable for welding process control.
In addition, the YAG laser and CO2 laser can also be combined into a dual-beam welding, continuous laser and pulsed laser combination for welding, but also a combination of focused beams and diffuse focus beam welding. By changing the beam energy, spacing or the energy distribution of the two beams, the welding temperature field is adjusted to change the pattern of the melt hole and the flow of liquid metal, which provides a wider range of options for the laser welding process.
