Aluminum and aluminium alloys have excellent properties, such as high specific strength and corrosion resistance. They are widely used in many industries, especially in national defense industry, machinery industry and other industries. Aluminum alloys belong to non-ferrous metals and need to be welded in the application process. Therefore, with the rapid development of science and technology, the welding technology of aluminium alloys is becoming more and more important. In depth. Therefore, laser welding technology is a great progress in science and technology.
Summary of laser welding technology: As a new welding technology, laser welding is directly the source of welding heat, which can not only avoid the waste of energy, but also greatly improve the efficiency of welding. At the same time, laser welding takes robots or CNC machine tools as a motion system, which reduces the participation of personnel, reduces the waste of labor and improves the efficiency of welding. Laser heat source not only has the advantages of renewability and clean and pollution-free, but also has high focus and good performance of transmission, so it can gather all the energy in one point, avoiding the loss and waste of heat. Therefore, laser welding can improve the efficiency and speed of welding and the quality of welding. Because laser welding beam is realized by pulsed or continuous laser beam, when laser beam directly irradiates the surface of aluminium alloy, it can diffuse the heat of metal surface rapidly to the inside of aluminium alloy, make aluminium alloy melt quickly to form a welding seam, at the same time, form a reaction force on the melted metal, and eventually concave the surface of molten aluminium alloy. The pit forms a small hole. This small hole has a powerful effect, can absorb all the energy produced by laser beam irradiation, and produce high temperature steam at the same time. The vapor pressure and the tension of the wall surface form a dynamic balance.
Laser welding has a certain power, only when the welding power reaches a certain height, can the welding be stable and sustainable. Otherwise, welding can only work on the surface of aluminum alloy, making the surface of aluminum alloy melt, so that the welding can not be successfully carried out. Laser welding power can reach or even be higher than the total welding height of aluminium alloy surface and interior, so laser welding aluminium alloy level can improve efficiency, speed and quality.
Because of the high power of laser welding, the speed of welding is also improved correspondingly. The penetration of aluminum alloy decreases with the increase of welding speed. On the contrary, if the speed is slowed down, the aluminum alloy will be over-welded or even penetrated. Therefore, the selection of laser welding can reduce the proportion of welding failure and greatly reduce the welding cost.
Improve energy density, improve welding quality, increase welding precision and density, high welding efficiency and speed, low welding cost, can be welded under special conditions, welding can have little impact on other parts of aluminum alloy.
In the oil pipeline, the application of aluminium alloy pipeline can increase the diameter of the pipeline, thicken the wall of the pipeline, so that the pipeline can transport more oil in a certain period of time. Oil transportation has a very high risk, such as oil leakage, which will cause incalculable property losses, casualties, environmental pollution and groundwater pollution. Therefore, special attention must be paid to improving the quality of welding for aluminium alloy pipelines. Laser welding can play a huge role at this time. Through laser welding, welding workers in line with welding can be controlled. The process can be operated without groove opening. The weld is formed once and the quality of the weld seam is high. It fully avoids the risk of oil leakage and improves the safety of oil transportation.
With the rapid development of the times and the increasing speed of people's living standards, it has become common to travel by car, and people are increasingly demanding for the quality of cars. Therefore, the automotive industry is constantly looking for new materials and technical means to improve the quality of cars. Laser welding technology has been more and more widely used in the automotive industry. The United States first introduced laser welding technology of aluminium alloy into the automobile manufacturing industry. After a series of experiments, the automobile made of laser-welded aluminium alloy was manufactured and formed after laser welding of thin aluminium alloy, which not only greatly reduced the weight of the body, but also reduced the manufacturing process of automobile, improved the manufacturing efficiency, and was welcomed by the automobile manufacturing industry. look at.
As we all know, the aerospace industry needs a series of spacecraft, such as aircraft, which are made of highly precise and precise materials, and the weight requirement of the machine itself is very strict. Making aircraft and other machines with laser welded aluminium alloy can reduce the fuselage by about 20% and the manufacturing cost has been greatly reduced. For example, the parts of A350 series aircraft manufactured by German co-tube parts manufacturer using laser welding aluminium alloy technology have achieved great success.
Aluminum alloy is a kind of non-ferrous metal, which has strong reflectivity to all kinds of light. Laser, as a more intense beam, is easier to cause reflection on the surface of aluminium alloy. In other words, the non-ferrous metal of aluminium alloy has high reflectivity and low absorption to laser. In addition, all metals have thermal conductivity, so aluminum alloy also has a strong thermal conductivity. It is easy to use laser welding, reflecting laser or quickly transferring the heat of laser, which ultimately leads to the failure of aluminum alloy welding. Therefore, in laser welding of aluminium alloy, we should pay close attention to and rapidly increase the power density of laser, prevent reflection or transmission, strive to use high density to weld aluminium alloy in extreme time, so as to avoid reflection and other problems.
Because aluminium alloy is active and easy to be oxidized, it is easy to adhere to a large amount of dust and moisture on its surface. Therefore, in the process of welding, if not prepared adequately, the surface adherence will easily remain on the surface of aluminium alloy with the rapid laser welding, which will affect the quality and welding effect of aluminium alloy. Therefore, before welding aluminium alloys, it is necessary to clean the surface of aluminium alloys and remove oil stains on the surface. At the same time, it is necessary to thoroughly clean the oxide film on the metal surface and remove the oxide film thoroughly to prevent the explosion and other security threats caused by oxidation during welding.
Although laser welding has high efficiency, high speed and can reduce costs greatly, laser welding also has many shortcomings. Only when these shortcomings are fully understood and solved, can laser welding technology of aluminium alloy be more widely used.
It is suggested that proper porosity can maintain the internal and external balance of aluminium alloy. However, excessive bubbles will have a lot of defects. It is difficult to avoid a large number of porosity. When a large number of pores appear, the porosity is unstable, and the internal channeling of aluminium alloy will easily lead to cracks in the welding site. Therefore, the removal of porosity will be a major breakthrough in laser welding technology of aluminium alloy. Defects.
When using laser technology, it is necessary to increase temperature and density in order to achieve the purpose of rapid welding, which is easy to cause special cracks on the surface of aluminium alloy, thus causing welding failure. In order to cope with hot cracks, scientists have come up with a solution, that is, filler materials are used in laser welding, but this method can easily lead to waste of resources and a lot of labor. A simpler way to deal with hot cracks is also an important problem to be solved by this technology.
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