In the modern engine technology to enhance difficulty growing, battery efficiency is not satisfactory under the background of both traditional fuel vehicles, and new energy vehicles, lightweight technology are the basis of a common technology. As one possess many properties of light aluminum alloy materials, become a lightweight automobile technology development in the material of choice.
Body mass of car a total quality 40%, for vehicle weight, body weight plays a very important role.
Us today to talk about key manufacturing technology of aluminum alloy used for automotive body parts, including aluminum alloy automotive sheet metal and tube hydro-forming process of stamping forming technology, profile extrusion, sheet metal temperature and structure of casting (cast aluminum) forming technology.
| Application of aluminum alloy car body
Grades of aluminum alloy according to the non-aluminium-containing species with different content, from 1000 to 9000 all nine series.
Car body with aluminum material main including: copper pigment content highest, and hardness also high of 2000 Department, main containing magnesium elements, and and said "magnesium aluminum" of 5000 Department, magnesium Silicon content high, and anti-corrosion and anti-oxidation performance good of 6000 Department, car body of different by force parts will used different series model of plate, and profile, and pipe and the high performance cast aluminum, aluminum material.
Skeleton parts: the largest part of the body force, 2000 series and 7000-series material, heat.
Outer part: body force part of the minor, with 5000 or 6000 series material.
Door parts: 5000 or 6000 series material.
Part of the floor: 5000 or 6000 series material.
Casting: high performance cast aluminum alloy, heat.
Aluminum alloy widely used in the automobiles
Aluminum castings are manufactured to carry large loads of parts, reduces the weight significantly but have high strength. These plates have a complex geometry, usually by vacuum die casting, so it has high strength. Aluminum castings with high ductility, good weldability, high plasticity, ensuring high security in case of collision. These types of aluminum alloy castings is 5000 or 6000 series aluminum alloy. Aluminum castings are mainly used to structure of electric vehicle battery pack the box more. Moschino for Note 4
Tesla Model s battery box
| Key manufacturing technology of aluminium alloy for automobile body parts
Main cast aluminum parts for auto body (cast aluminum) connectors, panels (sheet metal), extruded frame, hydraulic structure of formed sheet panels and pipe parts.
General stamping processing poor surface quality of aluminum alloy, low yield (about 70%), cannot meet the body parts with high precision, high reliability, high efficiency and low defect manufacturing requirements. Hydroforming of car body parts in Europe, Japan, South Korea and other developed countries access to a large number of applications in the automotive industry, equipment, high pressure up to 400 MPa, processed aluminum alloy engine cover plate both inside and outside, inside and outside the door and fender cover the loading application.
Large aluminum castings, aluminum hydroforming parts forming the two core technologies. Aluminum alloy automotive sheet metal and tube hydroforming process as shown below.
Hydro-forming technology
Compared with the stamping process, the advantages of hydroforming process is as follows:
(1) reduce the stock size, saving materials;
(2) improved forming limit, reducing road;
(3) part surface quality and dimensional accuracy greatly improved;
(4) reduce the cost of supporting the mold number and;
(5) reduce the amount of subsequent machining and welding;
(6) forming complex shape and deformation, which require high integrity parts.
This technology in foreign countries have become the mainstream of automotive lightweight technology, and toward integrated, fast, large, accurate development. While domestic success in the large-tonnage hydraulic forming machine has been developed, such as 1050 and 1600 t t material hydroforming equipment, but spread in domestic aluminum sheet hydroforming there are the following main problems:
(1) lack of knowledge based on aluminium hydroforming design. Knowledge not available to designers of hydraulic forming system, not comprehensive, our designers cannot or not be able to take into account the Hydroforming technology used in lightweight structures.
(2) hydraulic forming of aluminum sheet material forming technology and research of the quality control system for parts. Most conventional stamping forming of aluminum sheet materials and parts of quality control results do not apply to Hydroforming technology.
(3) a lot of tooling and the super high pressure hydraulic system for the industrialization of key technologies to be breakthrough.
(4) based on the aluminum sheet hydroforming equipment throughout the system is not perfect. Moschino Note 4 Cases
For these reasons, industrialization of parallel action-oriented system is not the actual application, tooling and mold development difficult, longer debugging cycle, thus higher cost models are still a novelty in the country.
Aluminum alloy automotive sheet metal hydroforming applications (Tesla Model s-side wall and floor)
Aluminum automotive tubing internal high pressure forming of parts (Jaguar and Tesla Model s P85D XFL)
Warm forming technology of aluminum alloy sheet forming properties of materials, process parameters and mold design, influence of lubrication and friction, and many other factors, and is still a pending further research and development of new technologies in sheet metal forming. If you get a breakthrough, you can provide an efficient prototyping parts--average hourly production (ASPH) of more than 540 pieces.
Car floor warm stamping process
In recent years, the aluminum alloy warm forming technology applied in car body. Currently, aluminum punch plate stamping technology for thermo-forming body there are still some problems, mainly in the following areas:
(1) forming must continue to improve. Local tensile ductility of aluminum alloy sheet is not good, easy to crack, especially more complex parts.
(2) part surface quality is not good enough. In order to avoid tension, often leading to insufficient stamping tensile, as the outer panels prone to local defects such as facial distortion, effects of surface quality.
(3) dimensional accuracy is not easy to master, rebound control. For these reasons, aluminum die development difficult, longer debugging cycle, thus the high cost, it is difficult to meet the high quality requirements of car body parts.
Automobile covering parts
| Profile extrusion
In body design, and applying the framework designed to make the body of static torsional rigidity is increased by 60%. Extrusion forming technology is bent one servo control of a frame profile extrusion forming technology, but also the main technical means of space frame design.
Countries such as Germany, Japan, the United States has put a lot of manpower and material resources to tackle large wide flat extrusion process of aluminum alloy, precision quenching and artificial ageing, finishing school and other key technologies. Some new compression techniques have also been developed, such as high speed extrusion, hydrostatic extrusion, no salvage and variable cross-extrusion and so on.
Many models owned by high-end cars such as Audi, BMW, Nissan series, GM Buick and Grand Hyatt and the Toyota Crown, are made of aluminum alloy as the bumper beam and energy-absorbing material.
Extrusion molding process starts from the product design. Product requirements determine the product of many parameters, such as products of mechanical processing and surface treatment performance and environmental requirements determine the type of extruded aluminum. Product design of shape also determine how aluminum Extrusion die shape.
When the design problem-solving, the actual extrusion process starting from extruded aluminium cast rod, by extruding heated before softening, and then into the spindle tube extruder sein, again driven by high power hydraulic cylinders front end with a dummy block extrusion rod, in the presence of strong pressure, softened after the cast aluminum precision extrusion forming hole of rod from the mold.
Extrusion molding die
Aluminum front bumper beam
Jeep front bumper beam
Extruding bent-integrated machining technology as shown below. Profile out of the die bending is achieved through a series of guides. This method can be used to precisely control the accuracy of bending of profiles, and you can easily realize the bend (bending direction and different parts have different radii of curvature). According to the bending stress, curved boot mode can also be adjusted from the extrusion die.
Extrusion bending-integration process
Extrusion process, since the common extrusion presses, motion is constant, the optimization of process parameters is difficult to achieve. Servo control systems combined with extrusion presses, will be able to realize any slider motion characteristic curve, slider position accuracy of 0.01mm, servo press trip can easily adjust according to process requirements, improving product quality and production efficiency, reduce the cost of production has a very important significance.
For the car's front rail, seat rails, bumpers, shock-absorbing structure section structure changes, the forming technology of stamping and welding is often used method, compression, expansion forming, these complex processes, high production efficiency, low cost, and welding parts will reduce stiffness and energy absorption characteristics. Extruding bent-shaped servo control method of manufacturing aluminum components in the structure, can significantly reduce the amount of the subsequent mechanical processing of semi-finished products, full of fiber reinforced high performance extrusion, thereby enhancing the body's strength and reliability.
| Structure of casting (cast aluminum) forming technology
Aluminum body frame (ASF)
Frame by frame structure of aluminum alloy casting and hydroforming of aluminium alloy combined into, including 35% high-precision aluminum casting, extrusion of aluminum alloy parts 22% and 35% aluminum alloy plate. Among them, frame fittings for aluminum alloy castings, this type of effect of the aluminum casting to the connecting body, is a major supporting parts, to have higher strength. In order to meet the need, the body structure for complicated thin-walled aluminum alloy castings. Because of these structural characteristics of castings, and the need for mass production of automotive industry, using traditional casting process has been unable to meet the requirements of foreign manufacturing aluminum alloy body castings are used vacuum pressure casting and extrusion casting a new squeeze casting process of special techniques.
Vacuum pressure casting is a new cast and special squeeze casting technology. Vacuum pressure casting and normal casting than increase the vacuum operation, the gas in the cavity can be drawn, metallic liquid in vacuum filling cavities, reduces the involvement of gases, heat treatment of castings, mechanical properties than conventional die castings. Special liquid metal extrusion can be achieved not only in squeezing casting and can be realized in extrusion of semi-solid metal slurry, paste have good liquidity as well as the microstructure of spherical, forming more complex castings and castings with excellent mechanical properties and high level of near NET shape.
| Aluminum body and reliable connection technology
Mechanical connection technique: high thermal conductivity of aluminum alloy, using conventional resistance spot welding technology to connect high power consumption, and quality assurance. At present, the foreign automakers are using SPR, since mechanical connection methods, such as aluminum alloy cutting screw connections.
Welding technology: aluminum body parts and connection technology, in addition to extensive use of lock rivets, cutting screws, self-tapping screws, rushed the process and glue (viscosity), non-melting connection methods, using MIG welding, laser welding (including laser welding, laser soldering) and laser-MiG arc hybrid welding, fusion welding methods. Among them,-MIG MIG welding, laser welding and laser-arc hybrid welding, friction stir welding aluminum welding technology standards body parts.
Flexible edge technologies: high precision autobody shape quality requirements strictly controlled, the traditional molded edge input, poor flexibility, rolling robot (roller hemming) became trend of flexible hemming. Mature foreign automotive equipment suppliers have a lot of flexible edge technology for aluminum alloy, for example Germany ThyssenKrupp, and United States Hirotec, and Germany Edag, and United Kingdom companies such as DVA. At present, the domestic aluminum panels supporting edging equipment suppliers are mainly European and US companies.
Lightweight automobile is the car of the future in energy saving and environmental protection, reduce pollution and other important aspects of development. As a typical lightweight aluminum alloy material is increasingly being recognized by the industry, so applications can be used more widely in the car, said all aluminum body is a trend of the future automotive lightweight.
"References"
1. Li Yongbing, Chen Changnian, Lang Lihui, Xie Hui. Research on key manufacturing technology of automobile aluminum body. Automotive technology and material, 2013 (3): 50-58.
2. Self-reliance, Zhai Haipeng, Wang Hao. Application of aluminum in automobiles. China Science and Technology Expo, 2014 (3): 320-320.
3. Take sign Erlang, Gao Kui source. Japan latest technology and development trend of aluminum alloy vehicle. Foreign railway vehicles, 2002,39 (2): 7-11.
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