Commonly used steels for making gears are quenched and tempered steel, hardened steel, carburized hardened steel and nitriding steel. The strength of cast steel is slightly lower than that of forged steel, often used in larger size gear; the mechanical properties of gray cast iron are poor and can be used in light loaded open gear transmission; spheroidal graphite cast iron can be partly replaced by steel to make gears; plastic gears are used for light load and low noise requirements, and usually with good heat conductive steel teeth with their paired gears. Wheel.
In the future, gears are developing in the direction of heavy haul, high speed, high precision and high efficiency, and strive for small size, light weight, long life and reliable economy.
The development of gear theory and manufacturing process will be a further study of the mechanism of tooth damage, which is the basis for establishing a reliable strength calculation method, a theoretical basis for improving the bearing capacity of the gear and prolonging the life of the gear, and the development of a new tooth profile represented by the arc tooth profile; a new type of gear material and a new tool for making gear. It studies the elastic deformation, manufacturing and installation error of the gear and the distribution of the temperature field to repair the gear teeth, in order to improve the stability of gear operation and increase the contact area of the gear in full load, so as to improve the bearing capacity of the gear.
Friction, lubrication theory and lubrication technology are basic work in gear research. Research on elastic fluid dynamic pressure lubrication theory, popularize the use of synthetic lubricating oil and adding extreme pressure additives in oil can not only improve the bearing capacity of the tooth surface, but also improve the transmission efficiency.