In today's rail transit, shipbuilding, and other industries, there is an increasing demand for welding of medium and large-thickness steel plates. In recent years, to promote the development of my country's shipbuilding industry, the government has successively introduced policies such as giving priority to the development of high-tech ships and high-value-added ships, accelerating the transformation and upgrading of the shipbuilding industry, and the trend of world shipbuilding is also moving toward large-scale, diversified, and high-end development. Welding technology is a key technology in ship processing and manufacturing and the development of the shipbuilding industry. Welding man-hours account for approximately 30% to 40% of the total shipbuilding man-hours. Welding production efficiency and welding quality directly affect the production cycle, cost, and hull quality of ship processing and manufacturing. Therefore, efficient and high-quality ship welding technology is an important factor in realizing the transformation and upgrading of my country's shipbuilding industry and is also an important factor in improving the international competitiveness of my country's shipbuilding companies.
In addition, with the rapid development of my country's railway train industry and the continuous acceleration of trains, bogies, as an important component of rail vehicles, carry greater dynamic loads, which puts forward higher requirements for bogie technology. The design of bogie frames Materials and processes must be continuously developed and improved to meet performance requirements. The quality of welded joints has become an important link to ensure the bogie frame's quality. Therefore, a more optimized welding method is a necessary condition.
Laser-arc hybrid welding arises in response to the needs
As a new welding technology, laser-arc hybrid welding uses laser and arc as dual heat sources, acting on the same molten pool simultaneously to form a laser-guided and stable arc. The arc improves the laser absorption rate of the metal and enhances the transfer and bridging of molten droplets. A capable welding method that gives full play to the advantages of laser welding and arc welding and makes up for their respective shortcomings. Especially in the welding of medium and large-thickness materials, hybrid welding technology has greater advantages. Because traditional welding methods have shortcomings such as low joint strength, low efficiency, serious deformation, and large consumption of welding materials; and single laser welding also has some shortcomings, such as high joint assembly process requirements and welding capabilities restricted by laser power. Large, poor bridging ability, serious undercutting of welds, etc.
As a new welding method, laser-arc hybrid welding has the following three significant characteristics:
1) Improve energy utilization, increase weld penetration depth and welding speed;
2) Reduce workpiece assembly requirements;
3) Improve weld quality and improve weld formation.
Wide range of applications
With the development of laser-arc hybrid welding technology, its application scope is becoming more and more extensive, especially in foreign countries, but rarely in China. It has broad prospects. Its main application areas are as follows:
1. Shipbuilding
Among all manufacturing industries, the shipbuilding industry is the biggest beneficiary of laser-arc hybrid welding technology. To maintain their advantages in the high-value-added shipbuilding industry, some European shipyards have widely adopted laser-arc hybrid welding technology, which has greatly improved welding quality and production efficiency in thick plate welding applications. A typical example is that Meyer Shipyard in Germany has adopted a laser-arc hybrid welding method for ship welding.
2. Automobile industry
Germany took the lead in applying laser-arc hybrid welding technology to the connection manufacturing of automobile doors, side panels, and other components. Scholar Graf T and others reported at the International Automobile Welding Forum "Application of Laser Hybrid Welding in Volkswagen and Audi Cars [C ]" It is reported that there are 66 welds on the front door of the Volkswagen Phaeton sedan, with a total length of 4.98m, including 48 laser-arc composite welds; the total composite welding length of the body frame of the Audi A8 sedan is 4.5m.
New energy vehicles are booming, and the core of their power is the power battery. To reduce the overall weight of the vehicle, the power battery trays are generally made of aluminum alloy. The trays are assembled and welded, and each tray has dozens of welds. , and the requirements for weld strength and welding efficiency are high. Traditional arc welding and conventional laser welding are difficult to meet the requirements, and laser-arc hybrid welding is a connection method that meets the needs very well.
3. Petrochemical industry
According to research on the laser-MAG arc hybrid welding process of oil transportation pipelines, it was found that compared with using laser alone as a heat source after welding, laser-arc hybrid welding can increase the penetration depth by 20%, and the welding process is more stable with a small amount of spatter. The seam is well formed, has a good melt-to-width ratio, and has no welding defects such as undercuts or lack of fusion. After welding, the pores are controlled within a certain range by X-ray inspection, which does not affect the quality of the welded joint and meets the engineering requirements.
Laser-MIG hybrid welding is used to weld oil tanks. Due to the addition of a laser, the weld penetration depth is greatly improved, so that single-sided welding can be performed, avoiding the inconvenience caused by double-sided welding. Not only the quality of welds has been improved, but also huge breakthroughs have been made in improving welding efficiency and production capacity. At present, laser-arc hybrid welding has been widely used in the German oil tank manufacturing industry.
4. Aerospace field
In the aerospace field, laser-MIG/MAG arc hybrid welding technology has also begun to be used in the welding of medium-thick plates and high-strength steel, achieving 7mm thick 3CrMnSiA laser-MAG arc hybrid welding without preheating, which greatly reduces workers’ labor intensity and Improved welding production efficiency.