Hydroforming During 1994 1997, the Ultra Light Auto Steel Body (U LSA B (Ultra Light Auto Steel Body) project for automobiles, which was jointly participated by 35 steel mills and automobile factories around the world, proposed that through the rational use of steel, A series of solutions to reduce the weight of the car body. In the ULSAB project, the three major technologies were mainly promoted, and the application of hydroforming technology in automotive structural parts is one of them. According to different raw materials used, hydroforming technology can be divided into tube hydroforming and plate hydroforming. Among them, the development of pipe hydroforming technology is more mature and widely used than plate hydroforming. This article mainly discusses the hydroforming of pipe fittings and the use of the required raw material welded pipes. In order to reduce the fuel consumption and save energy, the hydroforming technology of pipe fittings, the implementation of light vehicle weight and the reduction of vehicle weight is a main direction for the design of automobile structural parts. In automotive structural parts, many welded pipe parts are connected into parts by traditional welding technology. In the design of the car body, for these structures that mainly bear bending and torsion loads, hollow variable-section members can be used, which can reduce the mass and make full use of the strength and rigidity of the material. Pipe hydroforming technology is an advanced manufacturing technology of hollow variable-section light-weight components developed to meet this demand. The basic principle of pipe hydroforming is to use a pipe as a blank, and the pipe blank is pressed into the mold cavity to form the desired workpiece by applying an ultra-high pressure liquid and axial supplementary material inside the pipe. Because the internal pressure used can be as high as 400Mpa, in Europe, it is also called internal ing), in the United States, it is called tube hydroforming technology (Tube Hy ​​[1,2]]. The tube hydroforming technology has appeared since the 1980s Due to the high investment cost, its development has a peak and trough. With the increasingly fierce competition between steel and aluminum and the emergence of new materials, in the ULSAB plan, the hydroforming technology of pipe fittings has been vigorously promoted. The research and application of forming technology is still in the experimental stage. The schematic diagram of the principle of hydroforming of pipe fittings is shown in Figure 1. Pre-formed pipe fittings form complex parts under the action of high pressure inside the liquid. Figure 2 is a hydro-formed part made using hydro-forming technology. A major feature of hydroformed parts is that they can form complex structural parts to meet the requirements of the automotive industry. Resistance welding pipe (ERW) pipe fitting hydroforming technology, the raw material used is steel pipe. There are two types of seamless steel tubes and welded tubes. Seamless steel tubes have unique advantages such as excellent overall performance, but because the materials used for stamping parts in the automotive industry are mostly thin-walled materials and require certain stamping performance, seamless steel tubes cannot meet such requirements. One of the most commonly used welded pipes is the straight seam high-frequency resistance welded pipe, also known as ERW (Elec is formed by a molding machine, and the skin effect and proximity effect of high-frequency current are used to heat and melt the edge of the tube blank. Under the effect of pressure welding to achieve production. The advantage of resistance welding pipe is that the production efficiency is very high, but there is a fatal weakness is that its internal burrs cannot be removed completely. And with the use of high-strength steel, resistance welding pipe welding is reliable Sex will be reduced. Laser tailored welded tube (T WT) light welding method is formed by connecting preformed tubes, which is different from ERW. Compared with seamless extruded tubes and ERW tubes, laser tailored welded tubes have the following advantages: reduce production costs (especially for non-standard size round tubes) improve accuracy (compared to extruded tubes, the tube wall thickness accuracy is higher and more Stable) Round pipes of any diameter / wall thickness ratio within a certain range can be produced according to needs. The same pipe can have different wall thicknesses. The same pipe can have different materials. In the automotive industry, for welded pipes required for hydroforming, the use of laser tailored welded pipes and high-strength steel materials will be a trend. In UL Concepts, the use of laser tailored welded tubes is greatly promoted. The biggest advantage of laser tailored welded tubes is that they can have a large diameter to thickness ratio (d / t ratio), which is unmatched by general high-frequency resistance welded tubes. In the car body-in-white structural parts, with the use of a large number of high-strength steels, this requires the thickness of the steel plate to be thinner. Therefore, for the tubular structure, a larger d / t ratio and better formability are required. Laser tailored welded pipe is a new process that meets this requirement. The laser tailored welded pipe is similar to the laser tailored welded board, and different materials and different thicknesses can be combined to reflect the characteristics of tailored welding and has great flexibility. Parts made of tailor-welded tubes. Laser tailored welded tubes have been widely used in OPEL Automobile Company and BMW Company. In the BMW 7 series, a large number of laser tailor welded pipes are used, and the high frequency welded pipe technology of these pipe fittings cannot meet the welding quality. The subframe of a car shown in Figure 4 is made of laser welded pipes and then stamped using hydroforming technology. At present, such stamping parts have been widely used in Europe. The proportion of laser tailored welded pipes in the U LSAB AVC project is shown in Figure 5, which accounts for about 6. Laser tailored welded pipe is made by bending cold-rolled steel sheet and then laser welding. The production process is roughly: uncoiling and blanking the steel sheet → pre-bending the steel sheet → laser welding. Although the manufacturing process is not complicated, the gap required after the pre-bending of the steel plate is high, otherwise the quality of the laser welding cannot be guaranteed. There are two options for bending pipe forming, one is multi-roll forming and the other is UO forming. Figures 6 and 7 are schematic diagrams of two forming schemes. Each forming scheme has its advantages and disadvantages. In the production of laser tailored welded pipe, the bending of the pipe is a very important process, which directly affects the quality of the laser welding in the subsequent process. The application of laser tailored welded pipe has fewer welding defects, small heat affected zone, secondary processing ability and excellent corrosion resistance, and small burr defects after welding, which does not require internal burr treatment. But at the same time, the bottleneck that currently affects the large-scale use of laser tailored welded pipe is that its welding speed is lower than that of high-frequency welded pipe, and its production efficiency is much lower than that of high-frequency welded pipe. Therefore, laser tailored welded pipe is mainly used in parts with high quality requirements for parts and high-strength steel. At present, in the large industrial production field, the use of laser tailor-welded pipes to make hydroformed parts is relatively rare, and more is concentrated on sub-frames, exhaust pipes and other parts. UO forming schematic diagram conclusion The laser tailored welded pipe has strong flexibility, can use different materials in different parts according to the characteristics of users, and has the advantages of high welding quality. In the near future, it will be widely used in car structural parts. Will become an important supplementary form of raw materials used in hydroforming technology. Welding system, and experimental research on aluminum alloy laser MIG composite welding. Compared with simple laser or M IG welding, laser arc compound welding can significantly increase the penetration and improve the quality of weld formation. This article is funded by the Youth Scientific Research Fund of the Department of Mechanical Engineering of Tsinghua University. Liu Jichang et al., Modern Manufacturing Engineering, 2002 (9), 60 [6] Chen Yanbin et al. Laser coaxial arc hybrid heat source welding, Journal of Welding, 1995 Heated Eyelash Curler,Eyelash Curler,Eyelash Curler Set,Mini Eyelash Curler Yangjiang Yangdong Kartier Beauty Tools Product Factory , https://www.kartierbeautys.com
Application of laser welding pipe technology in car
Application of laser laser welded pipe technology in cars Yan Qi (Baoshan Iron and Steel Co., Ltd. Summary Hydroforming technology is listed as one of the three major technologies developed by the ultra-light car body plan for automobiles. The hydroforming technology of pipe is a kind of processing hollow The advanced manufacturing technology of light body parts is based on the principle of applying high water pressure inside the closed forming mold to expand the metal tube to the desired shape. Hydroformed parts have complex shapes and special properties. Parts are widely used. The raw materials used in hydroforming technology are steel pipes. In recent years, laser welded pipes have been rapidly developed as raw materials for hydroforming. Laser welded pipes can be made of different materials and can have different shapes. Such as column shape, cone shape, etc .. The laser welding technology is used to tailor the pipe so that the welded pipe can have different mechanical strengths in different parts, and there is no burr edge, and the flexibility is very strong. This article describes the laser welded pipe as a hydroforming raw material in automotive zero Widely used in components, and made laser welded pipe and straight seam resistance welded pipe Compared.