The active bevel gear of the central transmission device is installed on the shaft of the high-pressure compressor of the engine and rotates coaxially with the high-pressure rotor in the same direction and at the same speed. The driven bevel gear and the drive shaft change the rotation of the engine rotor into a rotation perpendicular to the axis of the engine, and transfer the power of the rotor to the outside of the engine. Requirements such as power, steering, and installation spacing drive engine attachments and aircraft attachment systems to work. When the engine is working, the torque transmission sequence of the transmission system is: high-pressure rotor driving bevel gear driven bevel gear engine attachment casing flexible shaft aircraft attachment casing. When the engine is started, the torque transmission sequence is just the opposite, that is, the turbine starter aircraft accessory box flexible shaft engine accessory box driven bevel gear driving bevel gear high pressure rotor.
Current status of gear materials China's engine technology is constantly improving, and the design and processing technology of transmission gears are constantly improving. However, gear materials have been dominated by 12Cr2Ni4A steel for decades, and there has been no replacement of steel grades. The smelting technology, forging technology and carburizing technology of gear steel have also made little progress. Compared with the gear material technology of Russia and other countries, the gap is large, and it is no longer suitable for the development of engine technology.
The manufacturing process of the transmission gear is basically the same. Generally, the rod is forged and processed by local forging, carburizing, high temperature tempering, quenching, ice cooling, and low temperature tempering. The carbide diffusion layer of the carburized layer is shallow, and the core tissue is coarse. The carbide diffusion layer of the carburized layer is deep, the hardness of the carburized layer decreases gradually from the front and back, and the heart tissue is finer. In addition to heat treatment technical factors, these differences are mainly determined by alloying elements. The structure of the carburized layer is ideal. The carbides are granular and evenly distributed. The hardness of the carburized layer decreases gradually from the surface to the inside. Although the metal flow lines of domestic gears are basically distributed along the shape of the parts, the flow lines of the teeth are mostly cut off, and the needle-shaped martensite structure of the carburized layer is more. The carbides in the carburized layer are mostly in the shape of angles and flakes, which are relatively thick and unevenly distributed. The hardness of the carburized layer decreases from the inside to the inside. Obviously, such a carburized layer structure is very detrimental to the wear resistance and fatigue performance of the gear.
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