Four key processes of automobile manufacturing: stamping, welding, painting and final assembly

Process refers to the most economical and scientific process and method of processing raw materials into means of production and commodities. As an automotive engineer, it is necessary to understand the four major processes of vehicle manufacturing. For a vehicle, process work and product design are closely related and complementary. The process leaves the design, it will inevitably cause waste, and the design leaves the process, and the product will be meaningless. Generally speaking, the four major processes of vehicle manufacturing are divided into: stamping, welding, painting and final assembly.

Stamping

Stamping is the sheet metal parts in accordance with the design requirements, the use of die stamping process. Stamping process plays an important role in automobile manufacturing process and is the first step in vehicle manufacturing. At present, most car bodies are made of steel plates and alloys. They are all made of stamping technology to form the appearance that designers want. Stamped parts include: left/right front fender, left/right outer panel, side wall rear (left/right rear fender), four doors, top cover, trunk panel, floor, front wall, etc. Stamping three elements: stamping equipment, stamping die, stamping plate. Stamping equipment is the so-called punching machine, which can realize cutting, punching, bending, riveting, forming and other operations. The selection of stamping equipment is generally carried out according to the production quantity, equipment size, etc. Generally speaking, the stamping equipment of the vehicle factory is divided into 2500 tons, 2000 tons, 1600 tons, 1000 tons, 800 tons, 500 tons and so on.

Stamping die is an important part of the production of various industrial products, it is a specific shape to make raw materials. Mold has become an important indicator of the degree of modern industrial development, but also to measure the level of a country's manufacturing one of the important signs. Stamping die can be divided into four basic units: blanking, bending, drawing, forming. According to the degree of process combination, it can also be divided into single process mold, composite mold, continuous mold and so on. In the design stage to consider the cost factor, to consider as little as possible to open the mold, mold changes, modifications need to do a good job of recording, to prevent unnecessary trouble.

Stamping plate: The car body is generally made of low-carbon steel, and the frame and covering parts of the car body are mostly stamped from steel plates. The special steel plate for the car body has the characteristics of not easy to crack after deep drawing. According to different positions of the body, more galvanized steel plates are used for rust-prone parts, such as fenders and top covers. High-strength steel plates are used in some parts that bear greater stress, such as radiator support beams, upper beams, B- pillars, etc. Car body structure commonly used steel plate thickness is 0.6mm ~ 3mm, most parts used thickness is 0.8mm ~ 1.0mm.

Welding

The stamped sheet metal parts are welded to form the body-in-white. In fact, the entire body structure is made up of pieces of stamping parts welded together. If the welding quality is not good enough, it may cause the body sheet metal to deform and crack, produce abnormal noise, and seriously affect personal safety. The welding workshop is generally connected with the stamping workshop to facilitate material transportation. The welding process generally adopts resistance welding, carbon dioxide shielded welding, etc. According to statistics, a vehicle has a total of 5000-6000 welding spots.

Welding fixture plays the role of support, assembly and fixation in the welding workshop. Basically, all welding parts need fixtures to ensure the correct assembly relationship, geometric size and shape, and also can improve work efficiency.

The welding workshop environment is bad, the noise is big, the air quality is poor, there is a certain danger (the welding current can reach thousands of amperes), the labor intensity is big. All workers in the welding workshop are required to wear masks, gloves (thread gloves + cut-resistant gloves + semi-leather gloves), labor protection shoes, aprons, safety helmets and other labor protection articles. With the development of science and technology, a better welding workshop of the whole vehicle factory can realize 90% mechanization and automation.

Welding Scenarios

Painting

Painting refers to spraying a layer of special paint on automobile sheet metal parts to protect metal and decorate beautiful. The coating process is more complex and requires high environmental requirements. It mainly includes the following processes: pre-paint preparation and primer, painting process, drying process, etc. A certain amount of chemical reagent setting and fine process parameter limitation are required in the whole process. The requirements for paint and various processing and development are very high. The coating process is generally confidential information of various companies.

For the painting of the car body, it is necessary to exercise for a long time under various weather conditions without the outbreak of paint film, deterioration and rust, and to maintain its luster, color and appearance. The general car body coating process is electrophoretic primer, intermediate coating and topcoat. If there is a weld between the electrophoretic primer and the intermediate coating, it is necessary to seal and spray the protective coating of the bottom plate to ensure the sealing, noise reduction and rust prevention of the car body.

Painting workshop layout and process flow chart

General assembly

The final assembly is the process of assembling each component on the BIW. Due to the large number of assembled parts, complex processes and different shapes of parts, mechanization and automation cannot be realized, final assembly is the workshop with the largest number of employees and more stations in the four major process workshops. Generally speaking, the assembly workshop can be divided into: interior decoration line, chassis line, assembly line, engine line, four-door line, instrument line, battery pack line, function line, rain line, quality door, etc. Each line body undertakes its own different work content, and finally all the parts are collected together, and after filling and programming, they are assembled into a qualified car.

The assembled car will also undergo a series of tests such as road tests and will eventually be sent to all parts of the country.