Welding is the most widely used and most important method for permanent connection of materials. It has unique advantages in improving material utilization, reducing structural weight, and reducing costs. laser pointer welding is the fastest-growing welding method in the past ten years. It uses a focusable and adjustable high-energy density laser beam as a heat source to achieve fusion welding of materials. The laser beam has excellent directivity, monochromaticity and coherence, the light intensity is 1010 times that of ordinary light, and the pulse power can reach 1014 watts, so the heat effect is concentrated and the welding deformation is small.
The welding structure has high manufacturing precision and good implementation of flexible automation. It is organically combined with advanced process modes such as robots, process databases and expert system management to realize digital and intelligent manufacturing. It is an indispensable key technology in modern equipment structure manufacturing. , Ships, high-speed trains and aerospace structures have been successfully applied. Among them, the automotive industry has identified laser welding as a standardized process for structural manufacturing. Laser welding technology is regarded as the most promising advanced welding technology in the world.
The development of laser welding applications along with the development of laser, metallurgy, materials, mechanics, measurement and control, information, electromechanical and other disciplines, is a comprehensive manifestation of the application of modern science and technology in the field of material processing, especially high-power laser welding technology above kilowatts , Almost accompanied by the progress of lasers. From the CO2 laser and YAG laser in the 1980s, semiconductor lasers and fiber lasers have been expanded. The laser power has been increased from 1kW to 100kW. The characteristics of typical welding lasers are shown in Table 1. Among them, fiber laser welding is the new laser welding process. Research hotspots.
Because of the different forms of heat action, laser welding can be suitable for different product objects, the key problems to be solved are also different according to needs. The most widely used blue laser pointer welding is the welding of thin-walled structures. The most typical aerospace structure is the aluminum alloy fuselage of the European Airbus aircraft. This welding instead of riveting structure will reduce the weight of the aircraft fuselage by nearly 20%. , Reducing the manufacturing cost by about 20%. The wall structure welding of Airbus A318, A380 and A340 series aircrafts has been applied. The number of wall panels will reach 18, and the total length of welds will reach 1,000 meters.
With the development of aviation structural application requirements, one application development of laser welding technology is laser composite heat source welding technology for medium-thickness structures. The purpose is to expand the application range of laser welding technology and solve the problem of high-precision and high-efficiency welding of medium-thickness structures in the future. Need, followed by pulse laser welding for precision welding of micro-nano structures, using microsecond, nanosecond pulse lasers to solve dissimilar metals such as copper and aluminum, metal matrix composite materials, ceramics and other non-metallic materials, and laminated materials related to aerospace structures ( Glare), carbon fiber reinforced composite materials (CFRP) weldability issues.