A car is composed of many parts, each part plays a different role, and it needs to be processed through different processing technology, and then it can be installed on the car for use. What are the processing technologies of automobile parts?
1、 Forging of automobile parts
Forging is widely used in automobile manufacturing. Forging methods are divided into free forging and model forging. Free forging is a method of forming metal blank on anvil under impact or pressure. The blank of automobile gear and shaft is processed by free forging.
2、 Casting processing of automobile parts
Casting is a production method in which molten metal is poured into the mold cavity and cooled and solidified to obtain products. In the process of automobile parts processing and manufacturing, there are many parts made of cast iron, which account for about 10% of the whole vehicle weight, such as air cylinder block, transmission box, steering gear housing, rear axle housing, brake drum, various supports, etc.
Sand mold is usually used to make iron castings. The raw material of sand mold is mainly sand, mixed with binder and water. The sand mold material must have a certain adhesive strength, so that it can be molded into the required shape and can resist the erosion of hot metal without collapse. In order to form a cavity in the sand mold in accordance with the shape of the casting, it is necessary to make a model of wood, called wood mold. The volume of hot molten iron will be reduced after cooling. Therefore, the size of wood mold should be increased according to the shrinkage rate based on the original size of the casting, and the surface to be machined should be thickened accordingly.
3、 Welding processing of automobile parts
Welding is a processing method that two pieces of metal are locally heated or simultaneously heated and pressurized. We often see workers holding a mask in one hand and welding tongs and welding rods connected with wires in the other hand. The welding method is called manual arc welding, which uses the high temperature generated by arc discharge to melt the welding rod and weldment and make them join.
Manual arc welding is not widely used in automobile manufacturing. Spot welding is widely used in automobile body manufacturing. Spot welding is suitable for welding thin steel plates. During operation, two electrodes apply pressure to two steel plates to make them stick and merge. At the same time, the bonding point (circle with a diameter of 5-6 μ m) is heated and melted by electric current, so as to firmly join. When two body parts are welded, a point is welded at the edge every 50-100 ° to form a discontinuous multi-point connection. It usually takes thousands of solder joints to weld the whole car body. The strength requirement of solder joint is very high, each solder joint can bear 5kn tensile force, even tear the steel plate, but the solder joint can not be separated.
4、 Cold stamping of automobile parts
Cold stamping or sheet metal stamping is a processing method to make the sheet metal be cut off or formed under pressure in the die. Daily necessities, such as aluminum pot, lunch box and washbasin, are made by cold stamping. For example, to make a lunch box, the first step is to cut out a rectangular blank with four rounded corners (referred to as “blanking” in the industry), and then the blank is pressed into the female die with a punch to form (referred to as “drawing” in the industry). In the drawing process, the flat sheet metal becomes a box shape, and its four sides are vertically bent upward, and the materials at the four corners accumulate and wrinkles can be seen.
5、 Automobile parts cutting
Automobile parts cutting is a kind of machining method which uses cutting tool to cut the metal blank layer by layer, so that the workpiece can get the required shape, size and surface roughness. Metal cutting includes fitter and mechanical machining. Fitter is a kind of machining method that workers use manual tools to cut. It is flexible and convenient to operate, and it is widely used in assembly and repair. Mechanical processing is completed by means of machine tools, including turning, planing, milling, drilling and grinding.
6、 Heat treatment of automobile parts
Heat treatment is a method to change the structure of solid steel by reheating, holding or cooling, so as to meet the use requirements or process requirements of parts. Different microstructure changes can be produced by heating temperature, holding time and cooling rate. The hardness of the steel parts can be improved by immersing the heated steel parts in water for rapid cooling.
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