Analysis of main applications of laser welding technology in the automotive field
According to relevant statistics, 50% to 70% of auto parts in industrialized countries in Europe and America are processed by laser processing, mainly laser welding and cutting. Laser welding has become a standard process in automobile consumption.
Laser welding application technology
1. Automotive body laser welding technology
The automobile body is a typical thin-plate shell structure, which is made of a low-alloy high-strength steel sheet by stamping, cutting, and shaping, and is assembled by welding. There are thousands of solder joints in the body assembly, and the conventional soldering is a resistance spot welding process. The resistance spot welding process uses two electrodes to press the workpiece from two directions, pressurizes and energizes the two lap joints, and forms a solder joint between the contact faces to weld the workpiece together. In order to satisfy the combination and shape requirements, a certain interval should be maintained between the solder joints. When spot welding, the welding tongs are welded under the edge of the workpiece, the flange width needs 16mm; and the laser welding is unilateral welding, the flange width is only 5mm. Change the spot welding to laser welding. This alone can save 40kg of steel per car.
The narrow and deep welds formed by laser welding easily penetrate the workpiece. There is no mechanical contact between the laser head and the part to be welded, and there is no machining mechanical stress. The tensile strength and fatigue strength of the laser weld are equivalent to those of the base metal, which meets the bearing capacity requirements, so that the material of the component can be thinned and the weight of the vehicle body can be reduced. At the same time, since the laser welding is controlled by computer, it has strong flexibility and maneuverability, and can be used for welding special-shaped door panels, baffles, gears, instrument panels, and the like. With the addition of fiber optic transmission systems and robots, automation of the automotive assembly line can be completed.
Automotive parts using tailor welded blanks
2, laser tailor welding technology
Laser tailor welding technology is one of the most successful and most effective technologies for laser welding in the automotive industry. When the automotive industry first applied the tailor welded blanks, in order to solve the problem that the width of the steel plate rolled by the rolling mill was insufficient, the tailoring technology was used to satisfy the requirements of the automotive industry for wide plates. With the development of the automobile industry, the tailor welded blanks are developed in the direction of the poor plate, and the steel plates of different thicknesses can be welded together. At this time, the purpose of the welding of the steel plates is truly achieved. ThyssenKrupp, which invented the laser tailored blank technology, first applied this technology in the consumer manufacturing of the Audi 100 in 1985. Laser tailor welding technology is to select steel plates with different steel grades, types, grades and thicknesses according to the performance requirements of different parts of the vehicle body. Through laser cutting and tailor welding, a certain part of the vehicle body, such as side wall and bottom plate, The inner door and the pillar of the door are welded together and then formed into a stamp. The purpose is to reduce the weight of the vehicle under the premise of ensuring the strength of the vehicle body. This technology has a number of advantages:
(1) Reduce the number of parts and a large number of equipment and processes for stamping. Tailor-welding can be integrally formed. According to the different requirements of different parts, the sheets of different thicknesses are welded together and stamped and formed again. At the same time, the accuracy of the vehicle body can be improved, and the equipment, processes and molds of a large number of stamping processing can be reduced.
(2) Reduce the weight of the components. Due to the use of different steel plate splicing, coated steel plates can be used for corrosion-prone parts to improve service life, thinner steel plates can be used for parts that are not subjected to load or load, and high-strength steel plates can be used for load-bearing parts. Welding ribs are no longer needed, which greatly simplifies the body structure, thereby reducing steel consumption and consumption costs, reducing body weight and ultimately reducing vehicle energy consumption.
(3) Improve the structural quality and reliability of the components. Due to the continuous welding instead of the discontinuous spot welding and riveting, the rigidity and tightness of the body and the safety are greatly improved.
(4) Providing the possibility to consume wide-body cars. Due to the limitations of the rolling mill, it is impossible to consume steel sheets that are too wide, and the demand for wide sheets in automobiles is becoming increasingly urgent. The use of laser tailor welding is an effective and economical process. Laser tailor welding makes the car look more beautiful and quiet.
Based on the analysis of the body structure, the optimization of imagination, the selection of a few typical steel plate welding, can improve the material utilization, save the secondary processing process, and greatly reduce the number of molds. After the use of tailor welded blanks by Toyota Motor Corporation's side wall consumption line, the number of parts was reduced by 66%, the number of molds was reduced from 20 to 4, and the material utilization rate was increased from 40% to 65%. With laser tailor welding, a medium-sized car can lose 9kg without affecting its strength.
At present, large foreign steel companies are vigorously developing laser welding consumables. ArcelorMittal has 35 laser welding consumables, its products in the European market share of more than 50%; Italy Solblank has 14 laser welding consumables into the consumption, but also ready to establish in the United Kingdom and the United States 4 laser tailoring lines; ThyssenKrupp has established a laser tailoring joint venture in Indonesia and the United States (Detroit); British Steel has built a specialized center (enterprise) that can provide tailor welded blanks to automakers; Japan has also established similar companies. At present, the tailor-welded plates consumed in Western Europe account for 70% of the world's total output, 20% of US consumption, and 10% of Japanese consumption.
Some Chinese automakers have adopted laser welding technology in some new models. For example, Shanghai Volkswagen has adopted laser welding technology in the manufacture of new car bodies. Wuhan Huagong Laser Engineering Co., Ltd. has provided hundreds of sets of front longitudinal beams. Thick laser welding board, the welding quality has reached the European imagination standard. ThyssenKrupp Angang Zhongrui Laser Tailored Blanks Co., Ltd. is the first laser tailored blank consumption line directly for automobile manufacturers in Anshan Iron and Steel Co., Ltd. It marks an important step for Anshan Iron and Steel in the deep processing of cold rolled products.