Application of aluminum alloy in lightweight of rail transit equipment

Aluminum alloy has a series of excellent characteristics such as low density, high specific strength and stiffness, good conductivity / thermal conductivity, shock absorption and damping resistance, electromagnetic shielding and high energy absorption at high strain rate. Therefore, it is widely used in aerospace, rail transit, shipbuilding industry, 3C electronic products and other fields.

Application of aluminum alloy in lightweight of rail transit equipment

Aluminum alloy is the first metal structure material used for lightweight transportation equipment. At present, the high-speed train body in various countries has basically adopted aluminum alloy frame. In addition, many parts such as car body top cover and gearbox box have also been made of aluminum.

Aluminum alloy has been widely used in rail transit equipment products in various countries because of its light weight, corrosion resistance and good formability, mainly including car body and parts with lightweight demand.

Aluminum alloy car body

The development of large-scale aluminum alloy profile production technology makes it possible for train modernization and lightweight. For rail vehicles, the weight of the body structure accounts for about 15% ~ 30% of the weight of the whole vehicle. Therefore, the weight reduction of the body is of great significance to the speed-up of vehicles. In Japan, the complex thin-walled porous hollow profile produced by 6n01 alloy (i.e. 6005 alloy) with better extrusion performance, welding performance and stress corrosion performance has been developed, which has successfully replaced 7N01 and 7003 profiles and is widely used in the structure of car body floor, side plate and roof. In Europe and America, al-mg-si6005a extruded profile with good extrusion performance and simplified production process is mainly used for aluminum alloy car body, which effectively solves the problem of stress corrosion on the premise of maintaining strength. In addition, 6061, 6063, 6082 and 6085 extruded profiles are also gradually popularized. In terms of body plate, 5083 deformed aluminum alloy is the most widely used]. The research on aluminum alloy car body in China started late. In 1989, Changchun Bus Factory developed the first subway train with aluminum alloy body in China. The car body adopts plate beam structure, which has complex process and high cost and has not been popularized on a large scale. In 1996, the former Ministry of Railways organized the development of ice2 aluminum alloy car body and manufactured the first mixed structure aluminum alloy car body in China, which promoted the technical development of aluminum alloy profiles for vehicles by domestic enterprises. In 2001, Changchun Bus Factory of CNR group built the first automatic production line of aluminum alloy car body in China, and developed and manufactured aluminum alloy car bodies of EMUs (210 km / h), high-speed test trains (270 km / h) and metro vehicles with domestic materials. CSR Nanjing Puzhen rolling stock factory, Zhuzhou Electric Locomotive Factory and CSR Tangshan rolling stock factory have also successively established production lines and began to produce aluminum alloy car bodies. In 2007, the aluminum alloy car body of 300 km / h EMU (see Figure 1) independently designed and manufactured by Qingdao Sifang locomotive and rolling stock Co., Ltd. was successfully offline. Up to now, the R & D and manufacturing technology of aluminum alloy car body in China has ranked among the advanced in the world and is widely used in rail transit equipment such as EMU and subway train.

With the upgrading of rail transit equipment, its weight reduction is not limited to the car body, and more parts made of traditional steel materials have been replaced by new high-strength aluminum alloys. At present, the gear box, air spring support, axle box body, motor end cover and other parts of ice in Germany, Shinkansen in Japan and TGV in France are generally made of high-strength aluminum alloy. China's "Blue Arrow" and "China Star" high-speed trains developed during the Ninth Five Year Plan period also use a large number of air trains made of aluminum alloy materials

Core floor, side baffle, motor end cover, motor fan, gearbox, etc. With the continuous development of rail transit equipment in the direction of high speed and heavy load, there is an urgent demand for lightweight bogie components such as traction motor, wheel set, transmission plate, axle box body and traction rod. Cast aluminum alloy and forged aluminum alloy are increasingly widely used in these components, and forged aluminum alloy has more advantages in strength, elongation and impact toughness. The materials used for aluminum alloy forgings are mainly 2A14, 6082 and 7050, 2A14 aluminum alloy

The forging has moderate strength after heat treatment and is suitable for parts with large load; 6082 aluminum alloy forgings have good welding performance and are suitable for parts that need to be welded with other parts [13]; 7050 aluminum alloy forgings have excellent comprehensive mechanical properties and stress corrosion resistance, and are suitable for dynamic load parts. Chalco aluminum is a 7050 high-strength forged aluminum alloy axle box developed and manufactured by domestic enterprises, which has been loaded in batches and applied to exported Macedonian EMUs, Czech EMUs and other projects. The finished single piece of aluminum alloy axle box body is about 45 kg, which is only equivalent to 1 / 3 of the single piece of cast steel axle box body. Calculated by installing two axle box bodies for each wheel set, a single wheel set can reduce 170 kg, and the weight reduction effect is considerable.

Chalco aluminum is the physical drawing of die forgings of motor swing rod and axle box pull rod for bogie produced by domestic enterprises. The product material is 2A14. This brand of aluminum alloy has good forging performance, moderate performance after heat treatment and small machining deformation. The process of each process of the same series of products is relatively mature, and now it has been stably produced and supplied in batches.

In addition, 7050 high-strength aluminum alloy is also used to produce the key part of the wheel set hollow shaft driving device - the transmission plate. The traditional transmission plate structure is a large steel forging with a mass of 100 kg. After using aluminum alloy material, the mass is only about 35 kg. As an important part of the unsprung mass of the bogie, its weight reduction plays an obvious role in improving the dynamic performance of the whole vehicle.

To sum up, according to the analysis of the application of aluminum alloy in the railway industry, the lightweight design of rail transit equipment at this stage

The metal structural materials used are mainly aluminum alloy, supplemented by magnesium alloy. The related technology of aluminum alloy in rail transit industry has been relatively mature. The next research focus is to develop new high-strength aluminum alloy, reduce the mass production cost of aluminum alloy and expand the application range of aluminum alloy.