Laser welding is a fusion welding that uses a laser beam as an energy source to impact the weldment joint. Laser welding is a non-contact welding. The process does not require pressurization, but an inert gas is required to prevent oxidation of the molten pool, and the filler metal is occasionally used. It does not need to be carried out in a vacuum, but the disadvantage is that the penetration is not as strong as electron beam welding. Accurate energy control during laser welding enables welding of precision micro devices. And it can be applied to many metals, especially to solve the welding of some difficult metals and dissimilar metals.
Laser brazing is one of the laser welding techniques. Due to the high energy density of the laser, it can be used as a heat source to melt the wire material. The laser light speed is focused and irradiated onto the surface of the wire. Under the traction of the robot, the molten wire material is infiltrated. On the welded industrial parts, the laser-fused welding wire is filled between the production workpieces to be welded, so that the production workpieces are well combined to complete the laser welding process. In the laser brazing process, the speed of the entire welding system is very fast, and the weld seam is relatively narrow, and the appearance is also very high. The welding system requires precise welding parameters, and the requirements for wire feeding speed and stability are also very high. high. The choice of solder is also important. Of course, there is no need to talk about cost savings, but also meet the design requirements, combined with the performance of the base metal, to achieve the heating conditions of laser brazing. This requires that the selected solder should have a suitable melting point, uniform composition, good stability, and firm bonding with the base metal.
Advantages of laser brazing
1. The parent material that is laser brazed does not melt by itself, only to melt the solder. The advantage of this is that the shape of the production workpiece is beautiful, the sealing is also good, and the safety is also good.
2. Local heating, not easy to cause thermal damage, less heat impact
3. There is no splash in the processing process, the weld quality is high, and the welding torch and nozzle need not be replaced frequently in the operation process, which saves the processing cost.
4. The laser heat source has high energy density, can be controlled and adjusted for heat input, and has high welding efficiency and is easy to automate.
Shortcomings of laser brazing
1. Although laser brazing is theoretically good, in the actual production, weld quality defects between workpieces will still occur.
2. Laser brazing is prone to porosity. For example, when the surface of the base metal is not clean enough, the relative position of the intersection of the laser beam and the laser beam is changed, and the surface of the weld is prone to stomata.
3. There may be a weld-welded weld and a single-weld weld, or the solder is not filled with welds or the solder extends beyond the weld surface, and the welding and brazing coexist. However, these defects are not the shortcomings of laser brazing. They are all technical problems.
4. The whole set of laser equipment is very expensive. If you invest in a very good sales model, it is not too expensive to allocate the cost to each vehicle. However, if the sales volume is not good, the bicycle cost is too high.
Known as the "most accurate ruler", "the fastest knife" and "the brightest light", the laser is one of the four inventions of the 20th century and computer technology, atomic energy technology and semiconductor technology. At present, lasers are widely used in various industries due to their superior characteristics, including sheet metal cutting, industrial manufacturing, food medical, aerospace and so on. With the vigorous development of high-tech manufacturing represented by new energy vehicles, laser technology has gained wider space. Currently, fiber lasers play a key role in industrial processing, especially in high power laser processing. Different types of lasers have different characteristics and thus have different applicability in different industry fields.
According to the division of working substances, the laser can be divided into gas lasers, including CO2 lasers, He-Ne lasers, etc.; liquid lasers using liquid dyes as pump sources; solid-state lasers, Nd:YAG, Nd:YVO4, Yb:YLP, etc. Semiconductor lasers and so on. According to the way of working, it can be divided into continuous laser and pulse laser. From the basic working principle, various lasers are similar, including the pump source, optical cavity and gain medium.
In laser marking, commonly used lasers are YAG lamp-pumped solid-state lasers, side-pumped solid-state lasers, end-pumped solid-state lasers, fiber lasers, and CO2 lasers. In terms of marking processing, many lasers are capable in this respect because the processing depth and strength are not very high. Side pumping and end pumping are primarily just differences in pumping direction. The CO2 laser is a gas laser with a wavelength of 10.6 microns in the far-infrared band, using CO2 gas as the pumping medium. In addition, a high voltage causes self-excited conduction in the rare gas, which in turn causes the gas molecules to release the laser.
Laser technology is widely used in industry, but it feels a little far from our living distance. In our daily life, in many places, the shadow of laser processing can be seen. For example, when you buy goods in general, you can see the labels, and many accessories on the clothing are laser processed. Previously used CD/DVD, laser printers often used in work, laser anti-counterfeiting marks, when paying for shopping. Barcode scanners for shop assistants, etc.
The types of lasers are far more than these, and with the continuous development of technology, laser technology is constantly infiltrating into more fields, bringing more changes to our lives.