威廉希尔官方下载Feb 09, 2020
The rapid development of aluminum alloy laser welding technology in recent years has broadened the application of aluminum alloys. This technology can combine the advantages of two heat sources at the same time, and at the same time can make up for their respective shortcomings. More and more popular.
1 Overview of aluminum alloys and their welding
Aluminum and aluminum alloys have very good properties, such as high specific strength and strong corrosion resistance. They have a wide range of applications in many industries, especially in the defense industry and machinery. Welding is required in the application process, so with the rapid development of science and technology, the research on welding technology of aluminum alloy is also getting more and more in-depth. Therefore, laser welding technology is a major advance in science and technology.
Overview of laser welding technology: Laser welding is a new type of welding technology. The welding heat source is directly laser, which can avoid waste of energy and greatly improve welding efficiency. At the same time, laser welding uses robots or CNC machine tools as the motion system, reducing personnel participation, which can reduce labor waste and improve welding efficiency. In addition to the advantages of reproducibility and cleanness without pollution, the laser heat source can also be highly focused and transmitted with good performance. Therefore, all the energy can be collected in one point to avoid heat loss and waste. Therefore, laser welding can improve the efficiency and speed of welding and the quality of welding. Because the laser welding beam is realized by pulse or continuous laser beam, when the laser beam directly irradiates the surface of the aluminum alloy, the heat on the metal surface can be quickly diffused into the aluminum alloy, so that the aluminum alloy is rapidly melted to form A welding seam, at the same time, forms a reaction force on the melted metal, and finally the molten aluminum alloy surface is depressed downward to form a small hole. This small hole has a powerful effect, which can completely absorb the energy generated when the laser beam is irradiated, and simultaneously generate high-temperature steam. The steam pressure and the tension of the wall surface form a dynamic balance.
1.1 Laser welding power
Laser welding has a certain power. Only when the welding power reaches a certain height can the welding be performed stably and continuously. Otherwise, the welding can only work on the surface of the aluminum alloy, which causes the aluminum alloy surface to melt and the welding cannot be successful Carry on. The power of laser welding can reach the height of welding the surface and the inside of the aluminum alloy, even higher than that, so the laser welding of aluminum alloy grade can improve the efficiency and speed and quality.
1.2 Speed of laser welding
Due to the high power of laser welding, the speed during welding is correspondingly increased. Increasing the welding speed can reduce the penetration depth. On the contrary, if the speed is slowed down, the aluminum alloy will be over-welded or even penetrated by welding. Therefore, choosing laser welding can reduce the proportion of welding failures and thus greatly reduce welding costs.
1.3 Advantages of laser welding
Improve energy density, improve welding quality, increase welding accuracy and density, high welding efficiency and speed, low welding cost, can be welded under special conditions, and have little impact on other parts of the aluminum alloy during welding.
2 Application of laser welding in various fields
2.1 Application in oil pipeline
In petroleum pipelines, the application of aluminum alloy pipelines can increase the diameter of the pipeline and thicken the pipeline wall of the petroleum pipeline, so that the pipeline can transport more oil in a certain period of time. The transportation of petroleum has a very high risk. If the oil leaks, it will cause unpredictable property loss, casualties, and environmental pollution and groundwater pollution. Therefore, special attention must be paid to the welding of aluminum alloy pipes to improve the quality of welding Laser welding can play a huge role at this time. Through laser welding, the welding process can be controlled. Welding can be performed without the need to open the groove. Once welding is performed, the quality of the weld is high and sufficient. The risk of oil leakage is avoided, and the safety of oil transportation is improved.
2.2 Application in the automobile manufacturing industry
With the rapid development of the times and the increasing speed of people's living standards, it is already common to go out and take cars, and people have higher and higher requirements for the quality of cars. Therefore, the automobile industry is constantly looking for new materials and technical means to improve The quality of automobiles and laser welding technology have become more and more widely used in the automotive industry. The United States was the first to introduce laser welding aluminum alloy technology into the automotive industry. After a series of experiments, cars made from laser welded aluminum alloys were manufactured by laser welding thin aluminum alloys, which not only greatly reduced the weight of the car body. Moreover, it has reduced the process of manufacturing automobiles, improved the production efficiency, and has been welcomed and favored by the majority of automobile manufacturers.
2.3 Application in the aerospace industry
As we all know, the aerospace industry needs highly accurate and precise materials to manufacture a series of spacecraft such as aircraft, and the weight requirements of the machine itself are also very stringent. The use of laser-welded aluminum alloy to manufacture aircraft and other machines can make the fuselage 威廉希尔官方下载ually it can be reduced by about 20%, and the manufacturing cost has been greatly reduced. For example, parts of the A350 series aircraft produced by the German condominium component manufacturer using laser welding aluminum alloy technology have achieved great success.
3 Difficulties of laser welding aluminum alloy technology
3.1 Aluminum surface is reflective to laser
Because aluminum alloy is a non-ferrous metal, it is highly reflective to various light rays. As a more intense beam, laser light is more likely to cause reflection on the surface of aluminum alloy. In other words, aluminum alloy is a non-ferrous metal. It has high reflectivity and small absorption for laser. In addition, metals have thermal conductivity, so aluminum alloys also have strong thermal conductivity. It is easy to reflect laser light or quickly transfer the heat of laser light when welding with laser, which eventually leads to welding failure of aluminum alloy. . Therefore, when laser welding aluminum alloys, strict attention must be paid to rapidly increasing the power density of the laser to prevent reflection or conduction. Strive to weld the aluminum alloy with extremely high density at extreme times, so as to avoid reflection And other issues arise.
3.2 Be fully prepared when laser welding aluminum alloys
Because aluminum alloy is active and easily oxidized, it is easy to attach a large amount of dust and moisture on its surface. Therefore, if sufficient preparations are not made during the welding process, things attached to the surface are easily left with the rapid welding of laser On the surface of aluminum alloy, which affects the quality of aluminum alloy and the effect of welding. Therefore, before welding the aluminum alloy, the surface of the aluminum alloy needs to be cleaned to remove the oil and the like from the surface. At the same time to prevent safety threats such as explosion caused by oxidation during welding, it is also necessary to thoroughly clean the oxide film on the metal surface and completely remove the oxide film.
4 Defects in laser welding of aluminum alloys
Although laser welding has high efficiency, high speed, and can greatly reduce costs, laser welding also has many shortcomings. Only after all these defects are clarified and resolved, can laser welding aluminum alloy technology be used more widely.
4.1 Stomatal defects
It was suggested above that moderate pores can maintain the internal and external balance of the aluminum alloy. However, excessive bubbles will have a large number of defects. It is difficult to avoid a large number of pores. When there are a large number of pores, the pores are unstable and chaos inside the aluminum alloy. It is easy to cause cracks in the welded part, so removing blowholes will be a major defect that the aluminum alloy laser welding technology needs to break through.
4.2 Hot crack defects
When applying laser technology, it is necessary to increase the temperature and density to achieve the purpose of rapid welding. This is likely to cause special cracks on the surface of aluminum alloy, which makes welding failure. In order to deal with thermal cracks, scientists have come up with a solution, namely, laser welding Filling materials are used at times, but this method easily leads to waste of resources and large labor costs. Taking a simpler approach to dealing with thermal cracking is also a major issue that the technology is about to address.
The laser welding speed of aluminum alloy has a lot of advantages. It has been widely used in a variety of manufacturing fields and has also improved the quality and manufacturing speed of the machine itself. However, the laser welding technology also has many defects that lead to welding failure. With the continuous efforts of scientists, the welding technology will become more mature and widely used.