Laser welding is the use of a laser beam with excellent direction and high power density and other characteristics of the work. Through the optical system will be focused laser beam in a very small area, within a very short period of time the welding formed at one energy is highly concentrated in the source area, and thus the welding melt and form a solid solder joint and weld.
There are two kinds of laser welding: pulse laser welding and laser welding. The former is mainly used for the welding of single point of continuous and thin parts. The latter is mainly used for welding and cutting of large parts.
1, the characteristics of laser welding processing method
A, non-contact processing, without the need for the workpiece pressure and surface treatment.
B, solder joint is small, the energy density is high, suitable for high speed machining.
C, short time welding, both to the outside world without heat, but also to the material itself heat distortion and heat affected zone is small, especially for processing high melting point, high hardness, special materials.
D, do not need to fill metal, do not need a vacuum environment (can be directly carried out in the air), will not like the electron beam in the air to produce X ray of danger.
E, compared with the contact welding process, no electrode, tools, etc..
F, no noise, no pollution to the environment.
G, micro workpiece can be processed. In addition, the wall of the transparent material can be welded.
H, can be achieved through the optical fiber remote, common method is difficult to reach the site, multi-channel simultaneous or sub - time welding.
I, it is easy to change the focal length of laser output and solder joint position.
J, it is easy to carry to automaton, robot device.
K, the conductor with an insulating layer can be directly welded, the performance of a large difference between dissimilar metals can be welded.
2, the mechanism of laser welding
Pulse laser welding can be divided into melt and deep penetration welding heat fusion welding
Heat transfer and melting welding is that when the laser beam irradiation to the surface of the material, the material absorbs light energy and heat melting. The heat of the material surface layer continues to be transmitted to the material in a heat conduction mode until the contact surface of the two to be welded and welded together in one.
Deep penetration fusion welding is when high power density of the laser beam is irradiated to the material, the material is melt processing and even gasification to produce larger steam pressure, under the pressure of the steam, melt the metals were crowded around the irradiated (pool) presents one of the pits, with the laser beam to irradiate, more and more deep pits and penetrates into the one another in the workpiece. After laser irradiation, the molten metal that is squeezed out of the pit is returned to the pit.
These two kinds of laser welding mechanism, and the power density, irradiation time, material properties, welding method and other factors. When the power density is low, the irradiation time is longer and the welding piece is thin, the mechanism of heat transfer and melting is usually carried out. On the other hand, is based on the mechanism of deep penetration fusion based.