Low temperature assembly technology in automobile industry

The engine and gearbox need to be assembled at low temperature, which is more convenient and precise than the press in assembly! With the development of cryogenic treatment technology, the lowest temperature of our cryogenic assembly box is nearly – 150 ℃, which provides advanced cryogenic assembly equipment for automobile cryogenic assembly industry. It can be said that the engine changed the world because of the cryogenic assembly equipment.

Due to the expansion and contraction of the material, the assembled engine is not easy to leak oil in the cold and hot environment. At present, many automobile engine manufacturers in our country have also adopted the low temperature assembly process, so they can also build very good engines. Although there are some gaps with foreign brands, they will surpass one day! This is also why after the engine overhaul, the overall performance is seriously reduced. The sealing is not good! Although there is no oil leakage, but in the process of high-temperature and high-speed operation, there is a slight air leakage, the power will also drop, and the fuel consumption will naturally increase!

What is the principle of low temperature assembly?
The two parts have the case of using interference fit to transfer torque. In this case, the hole shall be heated and expanded, and the shaft shall be cooled and contracted. In this way, the hole and shaft in the original interference state become clearance fit, which can be smoothly inserted together. When the hole and shaft return to the same temperature, the hole and shaft are in the interference state, which can bear the predetermined torque and axial force.

It can be seen that the temperature of the shaft and the hole must be different in low-temperature assembly. If the temperature is the same, the shaft and the hole expand or contract the same, the matching property will not be changed, and the interference or interference. Therefore, when assembling at low temperature, the hole should be at a higher temperature, while the shaft should be at a lower temperature, so as to change the matching property from interference to clearance.
Low temperature assembly should use low temperature assembly box, also known as deep cold assembly equipment or interference assembly box. In the assembly workshop, there is a “cryogenic assembly equipment” that cools the workpiece to a low temperature, that is, a low temperature assembly box.

During assembly, take the workpiece cooled to low temperature out of the “cryogenic assembly equipment”, and the workpiece will not recover to room temperature immediately. Then, assemble the heated mating parts with them, and then recover to room temperature, and then complete the assembly.

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