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1. Introduction to welding
Welding: also known as welding and melting, is a manufacturing process and technology that bonds metals or other thermoplastic materials such as plastics through heating, high temperature or high pressure. Before the late 19th century, the only welding process was that blacksmiths used metal forging welding for hundreds of years. The earliest modern welding technology appeared in the late 19th century, first arc welding and oxygen gas welding, and later resistance welding.
Laser welding was not until the birth of lasers such as CO2 lasers and YAG lasers in the 1970s, which made laser welding truly applicable to production and life.
Well, my mind is a bit big
With its unique characteristics and advantages, laser welding technology has been widely used in the manufacturing industries of boilers, containers, pipelines, automobiles, ships, aviation, etc., and has become the first choice process technology in the modern manufacturing industry.
2. Laser welding principle
Laser welding is to use the focused laser beam to irradiate the surface of the metal workpiece, and use its huge power density to instantly vaporize the metal of the workpiece butt part and form "small holes" under the combined action of beam pressure and steam force. The metal vapor in the small hole will be ionized under the action of a high-power density laser, forming a certain amount of high-temperature plasma inside and above the small hole, and passing most of the light to the surrounding material through the small hole effect to make it dissolve. During the movement of the laser beam, the permeable metal quickly cools down to form a dense weld structure.
Of course, from the principle of laser welding, it can be seen that if you are not careful during operation, the following situation will be caused.
Yes, laser cutting
The advantage that laser welding technology has incomparable to other welding technologies is that it has four main characteristics: good monochromaticity, good coherence, good directionality and high brightness.
Laser is a great invention
The laser focus spot of the laser beam is small and has a high power density, which can generate very high temperatures in a small range, so that some high-cultural point and high-intensity alloy materials can be dried.
Laser welding is contactless processing and does not have any problems such as tool loss. In the case of large investment in the early stage, the investment in the later stage will be very small.
The laser heat-selecting zone is small, so as to avoid the quality problems caused by material deformation as much as possible, and the subsequent process is simple.
Laser welding has a high degree of automation and can be controlled by computers. The welding speed is fast and efficient, and it can be conveniently welded in any complex shape, which makes laser welding production efficiency very high, and the processing quality is stable and reliable, and can obtain high economic and social benefits.
3. Laser welding research
Since the main restrictive factor of laser welding is laser and welding metallurgy analysis, foreign research in the field of laser welding is much earlier than in China. Since the 1970s, foreign countries have invested heavily in the study of laser and laser welding metallurgy analysis, forming a number of famous research institutions, such as the Welding Research Institute (TWI), the Edison Welding Research Institute (EWI), the French Welding Research Institute (FWI), the Japan Connection and Solvent Research Institute (JRWI), the Ukraine Barton Electric Welding Research Institute (PEWI), the Welding Research Institute (ISF) of the University of Aachen, and the German Welding Society (DVS) are distributed across the country. The welding research center in South Korea is located in the KITCH of the Korean Institute of Industrial Production Technology of the Institute of Modern Science and Technology (KAIST). They all belong to national welding research institutions. Domestic laser welding research has been carried out on a large scale in the 1990s, forming the National Key Laboratory of Laser Technology, a famous laser research at Huazhong University of Science and Technology. In 2015, it broke the foreign monopoly with automotive laser welding technology to win the first prize of national scientific and technological progress; the domestic Harbin Welding Research Institute is also a research institute with rich achievements, leading the country in the field of laser welding research and has achieved fruitful results in welding robot research; the AVIC Aeronautical Manufacturing Engineering Research Institute has made achievements in laser welding in related fields.
4. Laser welding application
In the field of aviation manufacturing, laser welding technology has been successfully applied to the connection between the inner partition of the wing, the aircraft fuselage and the reinforcement ribs. And replaces riveting technology, which greatly reduces the weight of the aircraft. For example, after the introduction of laser welding, the total fuselage weight of the Airbus A380 aircraft is reduced by 18%, thereby reducing consumption and emissions and reducing operating costs.
A380 wall panel laser welding welds show excellent welds
As early as the 1990s, the laser melting process was used to strengthen the damping surface of the crown of the RB211 engine turbine blade. With the support of Rolls, the University of Nottingham in the UK has developed a blade repair system and has been used in the Rollss Overhaul Center. The maintenance range includes compressor blade tips, turbine blade sealing teeth, etc. Laser melting technology was further developed, and two blade automated laser melting production lines were successfully established. First, a high-quality cobalt-based alloy wear-resistant layer was prepared on the rotor blade serrated crown damping surface of the first and second stage alloy materials of two engines, JT8D and JT9D. The wear of the tip of the engine compressor blades can be repaired by using the cladding and lamination technology, which can effectively reduce the heat-affected zone and reduce the occurrence of blade cracks. The one-time pass rate of production can be stable at more than 95%, while the one-time pass rate of traditional TIG surfacing is less than 75%. In addition, laser welding is widely used in engine parts repair.
5. Major applications of laser welding in other fields
In the automotive industry, laser welding plastic technology can be used to manufacture many automotive parts, such as fuel nozzles, gear shift racks, engine sensors, cab racks, hydraulic fuel tanks, filter racks, headlights and taillights. Other automotive applications include the manufacturing of intake pipe light manifolds and the manufacturing of auxiliary water pumps.
In the field of medicine, laser welding technology can be used to manufacture liquid storage tanks, liquid filter equipment, hose connectors, ostomy bags, hearing aids, transplants, microfluidic devices for analysis, etc.
Since laser processing is a non-contact processing method, it does not generate mechanical extrusion or mechanical stress, so it is particularly in line with the processing requirements of the electronics industry. Such as: transformers, inductors, connectors, terminals, fiber optic connectors, sensors, transformers, switches, mobile phone batteries, microelectronic components, integrated circuit leads, etc. welding.
6. Development prospects
As a combination of modern technology and traditional technology, laser welding is particularly unique compared to traditional welding technology and has a wider range of application areas and application levels, which can greatly improve the efficiency and accuracy of welding. Its power density is high and energy release is fast, which can better improve working efficiency. At the same time, its focus is smaller, which undoubtedly makes the adhesion between the sewn materials better and will not cause damage and deformation of the materials, so there is no need for subsequent treatment after welding. Therefore, it is mainly applied to the field of high-tech, and in the future, as people's understanding and mastery of this technology continues to deepen, it will inevitably be applied to more industries and fields.
