Laser cutting is the most important technology in the application of laser processing at home and abroad. It mainly realizes the cutting, welding, drilling and engraving of various materials. The main applications of laser processing are CO2 and YAG. Among them, CO2 laser cutting and welding are the most widely used, accounting for 70% and 20% respectively, while surface treatment is less than 10%. The main applications of YAG laser are welding, marking (50%) and cutting (15%). In the United States and Europe, CO2 lasers account for 70-80%. In our country, 10% of the laser processing is mainly laser cutting, of which more than 98% of the CO2 laser power is in the range of 1.5KW ~ 2kW, while about 15% of the laser processing is mainly heat treatment, most of which are used for laser processing of automobile engine cylinder liner. This technology has high economic and social benefits, so it has a great market prospect.
1. High energy, good density controllability
The laser beam is focused to form a very small action point with very strong energy. There are many characteristics when it is used in cutting. First of all, the laser energy is converted into amazing thermal energy and kept in a very small area, which can provide a narrow straight edge slit, a minimum heat affected zone adjacent to the trimming and a very small local deformation. Secondly, the laser beam does not exert any force on the workpiece. It is a non-contact cutting tool, which means that the workpiece has no mechanical deformation, no tool wear, no tool conversion, cutting material does not need to consider its hardness, that is, the laser cutting ability is not affected by the hardness of the material to be cut, and any material with hardness can be cut. Thirdly, the laser beam has strong controllability, high adaptability and flexibility, so it is very convenient to combine with automatic equipment, and it is easy to realize the automation of cutting process; because there is no restriction on cutting workpiece, the laser beam has unlimited profiling cutting ability; combined with computer, it can arrange the whole plate and save materials.
2. Narrow cutting seam and small deformation of workpiece
The laser beam is focused into a very small spot, which makes the focus reach a high power density. At this time, the heat input by the light beam is far more than the part reflected, conducted or diffused by the material, and the material is quickly heated to the degree of vaporization and evaporates to form holes. With the relative linear movement of the light beam and the material, the holes continuously form narrow slits. The thermal effect of trimming is very small, and there is basically no workpiece deformation. In the process of laser cutting, an auxiliary vapor suitable for the material to be cut is added. During steel cutting, oxygen is used as auxiliary vapor to produce exothermic chemical reaction with molten metal to oxidize the material and help blow away the slag in the slit. Compressed air is used to cut polypropylene, and inert vapor is used to cut cotton, paper and other flammable materials. The auxiliary steam entering the nozzle can also cool the focusing lens, so as to prevent the dust from entering the lens seat, polluting the lens and causing overheating of the lens. Most organic and inorganic materials can be cut by laser. In the metal processing industry, which occupies an important position in the industrial manufacturing system, many metal materials, no matter what kind of hardness, can be cut without deformation. Of course, for high reflectivity materials, such as gold, silver, copper and aluminum alloys, they are also good heat transfer conductors, so laser cutting is very difficult or even impossible.
3. Adaptability and flexibility
Compared with other conventional machining methods, laser cutting has more adaptability. First of all, compared with other thermal cutting methods, as the same thermal cutting process, other methods can not act on a small area like laser beam, resulting in wide incision, large heat affected zone and obvious workpiece deformation. Laser cutting can cut nonmetal, but other thermal cutting methods can't. After more than 30 years of development, laser technology in China has made thousands of scientific and technological achievements, many of which have been used in production practice. The output of laser cutting and processing equipment is growing at an average rate of 20% every year, which has solved many problems for the technical transformation of traditional industries and the improvement of product quality. For example, laser texturing and chemical fiber technology is being promoted in large steel plants such as Baosteel and Benxi Steel, which will change China's automobile coverage The quality, function and price of laser marking machine and laser welding machine are in line with the current domestic market demand, with a market share of more than 90%.