The essence of laser cutting technology is to form a laser beam by focusing high energy to directly melt or vaporize the workpiece to be processed. At the same time, the melt or oxide is processed under the action of auxiliary gas to complete the entire cutting operation. Laser cutting technology is a very advanced mechanical manufacturing and processing technology, which plays a very important role in improving the core competitiveness and overall level of machinery manufacturing enterprises.
1 Characteristics of laser processing
Laser processing was originally developed and proposed by Germany in the 1960s. Its working principle is to use lasers to form high-energy particles to directly melt or vaporize the metal that needs to be processed, and then derive many processing technologies. Because the stability and anti-interference ability of the laser beam are very strong, and the influence of the external environment is small, many metal or non-metal materials can meet high-quality processing requirements and the processing accuracy is very high. The main advantage of laser processing technology is high precision. From the actual situation analysis, it can be summarized as “high, fast, good, economical and wide”.
(1) High. Laser processing has very high precision and high work efficiency, so it also has high economic benefits. For example, the equipment value of a laser cutting machine is 300,000 yuan. In the production of the enterprise, the equipment cost can be recovered in one and a half years, and then profits can be generated.
(2) Fast. Laser processing technology can achieve high-speed processing. Because laser has high energy and is a high-energy light source, the processing speed is very fast, up to 100 m/min.
(3) Good. Laser processing technology has a very strong anti-interference ability and can resist the erosion and influence of the external environment. Therefore, the quality of the processed workpieces is good, which is unmatched by ordinary processing machine tools.
(4) Province. Laser equipment for product processing can comprehensively improve material utilization. Analysis of current statistical data shows that compared with other processing technologies, laser processing can save 10% to 30% of materials. In addition, laser processing does not directly contact the material being processed, so consumables are consumed less.
(5) Wide. Laser cutting technology can process a wide range of materials. In addition to metal materials, it can also process non-metallic materials. In addition, laser cutting technology can process a variety of processes, such as straight lines, curves, special-shaped patterns, etc.
2 Main types of laser cutting technology
(1) Vaporization cutting.
Vaporization cutting is a technology with a wide range of current laser cutting technology applications. The laser power density used in this technology is very high. As long as the laser is directly irradiated onto the surface of the workpiece, except for a very small amount that is reflected, most of the rest will be absorbed and converted into heat energy, which can reach the boiling temperature requirement on the surface and complete the process. Processing operations. In addition, from the analysis of the actual situation of surface oxidation, the effect of increasing the absorption rate is very obvious. The ejected steam will take away more molten material, and then a vaporization cut will be directly formed. Vaporization cutting technology generally uses pulse laser for processing, such as plastics, wood, ceramics, etc. can be processed.
(2) Melting cutting.
In the application of melting cutting, the power requirements of the laser are relatively high, and the performance requirements of the surface processing strength of the workpiece must be met. There is a big difference between fusion cutting and vaporization cutting. The melt formed after processing is not cleaned by vaporization, but requires the use of auxiliary gas for blowing. Melting cutting technology does not have problems with the emission and absorption of laser beams by vapor. When the laser beam moves within the incision gap, it interacts with the material on the front side. In addition, since the laser beam during melting and cutting is directly projected onto the inclined surface of the workpiece material, the angle formed by it is relatively large, so it cannot be melted immediately after absorbing the energy of the laser. At this time, it must be completed one by one, and wavy patterns will be produced after the final cutting. form.
(3) Reaction melting cutting.
The application of this technology is to use the laser beam to reach the ignition point on the surface of the workpiece, and then use industrial pure oxygen to form an oxidation reaction with the material, eventually releasing a large amount of heat. At the position of the incision, the material will form molten oxide after oxidation and combustion, and the material will be blown away When the incision is formed later, more heat will be supplied to the adjacent material to allow it to meet the ignition point requirements. At this time, the smooth progress of the reaction melting cutting can be ensured. The laser power used by this technology is smaller, only about 1/20 of that of vaporization cutting, and it has now become the main technology for cutting steel, titanium and other materials.
3 Application of laser processing technology in machinery manufacturing
With the development and progress of science and technology, the level of laser cutting technology has also been greatly improved, and it is continuously used in the field of machinery manufacturing. Here are some common technologies.
(1) Application of laser processing technology in the field of plate cutting and blanking.
The principle of laser cutting is that the laser beam formed by the laser oscillator is focused using a focusing mirror, and then high-density energy is directly irradiated to the surface of the material, allowing it to melt and evaporate, and then complete the processing process. Compared with other thermal cutting methods, because the unit energy of laser is very large, it can achieve high-precision cutting. In the current field of sheet metal processing, the most important laser cutting technologies include two types, namely CO2 laser cutting machine and fiber laser cutting machine. CO2 laser cutting machines have been developed and applied for a long time, and are not as advanced as fiber laser cutting technology. The wavelength is about 1/10 of optical fiber. The propagation is usually completed in an optical path isolated from the outside air. Fiber laser propagates in the optical fiber, with good passability, high energy concentration, little thermal impact, smaller cutting line width, and higher processing efficiency, so it can Effectively improve material utilization and prevent thermal deformation problems. In addition to conventional laser cutting blanking technology, laser cutting technology has very obvious advantages when applied to round hole cutting, reserved hole process gaps, and process sample production. It replaces drilling for processing, and work efficiency is greatly improved. It can also reduce the cost of templates.
(2) Application of laser processing technology in the field of welding. The most widely used methods of traditional mechanical welding technology are gas shielded welding, submerged arc welding, and argon arc welding. The resulting welding products have many defects and cause serious deformation problems. At the same time, the presence of welding arc light can easily lead to light pollution. , there will also be problems of dust pollution, threatening the lives and health of workers. The development and progress of science and technology have significantly improved welding quality and efficiency in industrial production, and can also reduce personnel labor intensity, and have been fully applied to processes such as robot welding and assembly line operations. At the beginning of research and development, because the laser power was relatively low and the level of laser welding technology was low, it could not process medium-thick and thick plates. However, with the development of science and technology in our country, comprehensive tests of laser welding technology for medium and thick plates have continued to increase, and high-power laser deep penetration welding, arc hybrid welding, ultra-narrow gap multi-layer filler wire welding and vacuum negative pressure laser welding have been formed. and other welding methods. Laser arc hybrid welding technology has been effectively applied on mechanical crane booms. It can directly combine two completely different heat sources with energy transmission mechanisms and physical characteristics to achieve unified welding operations and fully demonstrate the advantages of the two heat sources. Welding The seam penetration is large, the gap bridging ability is good, and the welding speed is very fast, which can effectively improve the processing effect. For example, the outrigger of the truck crane is made of high-strength steel with a yield strength of 960 MPa, using laser-twin wire MAG hybrid welding. Compared with traditional welding technology, this technology can be adapted to a variety of applications, especially highly reflective, difficult to weld, and dissimilar materials. It has good welding stability, improves welding deformation, avoids welding defects, and improves welding quality. improvement; work efficiency is increased by more than 3 times. Compared with single heat source welding, hybrid welding can increase penetration by 50%, promote welding speed, and complete welding operations with smaller inputs; high filling efficiency, saving 30% of welding wire % about.
(3) Application of laser processing technology in the field of remanufacturing. With the development of the field of mechanical remanufacturing, it can achieve energy saving, which is in line with my country’s green development strategy. At the same time, it can also ensure that the product performance after remanufacturing is completely consistent with that of new products, while the cost can be reduced by 2/3. Therefore, companies are more willing to invest. Parts remanufacturing is mainly for the processing of certain damaged parts. At present, the most critical one is efficient laser surfacing technology. Its principle is to process through high-density and high-power laser beams to form a micro-melted layer on the surface of the substrate. The structure is then pre-assembled or simultaneously added with direct fusion metal materials of specified composition, which can effectively promote the repair processing of worn parts and realize the remanufacturing of materials. The flexibility of this technology is very good, and the cladding materials for parts can be selected arbitrarily to meet the requirements for differentiated product processing. For example, the tensioning spring barrel of the chassis track of a high-power bulldozer has serious wear problems during work. The remanufacturing process can use laser cladding additive processing on the worn parts. After the processing is completed, it is tested from multiple aspects and found to be fully qualified in hardness. , the hardness gradient of the cladding state layer is reasonable, the metallographic structure meets the specified requirements, the service life is extended by about 30%, and it also has high economic benefits, avoids the waste of materials or components, and has good overall benefits.
(4) Application of laser processing technology in the field of quality management. The ISO9000 quality management system implements full-process monitoring and management of parts and components, allowing product quality to be traced. For traceability management of parts, machinery factories usually need to add permanent markings on the parts and directly mark the product name, material number, drawing number, manufacturer, date, QR code and other information. The traditional marking technology is cylinder Continuously impact the parts and then form a motion trajectory. The disadvantages of this method are loud noise, blurred writing and easy deformation of signs. Laser marking technology can achieve non-contact processing and form graphic and text marks on the surface of parts. The main advantages of this method are ① The processing speed is relatively fast, which is about 11 times higher than that of the traditional method; ② The writing is clear and only requires computer typesetting and production, and even complex patterns can be typed directly, and the effect is very good; ③ No-contact processing, There will be no pollution problems or damage to the workpiece, fully meeting traceability requirements.
4 Conclusion
Although laser processing technology is becoming increasingly mature and is widely used in the field of modern processing and manufacturing, however, under the background of comprehensive technological innovation in our country, laser manufacturers need to actively develop higher-level laser equipment and effectively improve machinery. The overall level of manufacturing processing. In the future, laser technology will inevitably have a broader space for development and contribute to the overall development of my country’s machinery manufacturing field.
