The application of special gears, the development of planetary gear devices, the development of gear devices with low vibration and low noise are some of the characteristics of gear design.
In order to miniaturize the gear device, the load bearing thrust of the existing involute gear can be increased. Countries widely use hard tooth surface technology, improve the hardness to reduce the size of the device; Special tooth shapes represented by circular gear can also be applied.
With the adoption of circular gear in the main transmission system of the shipborne helicopter developed by Britain and France, the height of the reducer is greatly reduced. With the trend that ship power is replaced by medium speed diesel engine, it is effective to use high power planetary gear device in large ships. Nowadays, planetary gear is used more and more for its small size, good coaxiality and high efficiency in large transmission devices such as metallurgy, mining and cement mill. Due to the development of mechanical equipment to large scale, the working parameters of gear have been improved. For example, the transmission power of high-speed gear is 1000-30000kw. The circular speed of gear is 20~200m/s (1200-12000r/min), and the design working life is 5X104-10x104 hours; The circumferential speed of rolling mill gear has been increased from a few meters per second to 20m/s, or even 30 ~ 50m/s. Transfer torches up to l00~200t.m, the service life is required in 20 ~ 30 years. These gears generally have accuracy grades 3 to 8.
And the stationarity and noise have higher requirements. For high speed gears (including turbine gears). When the circular velocity exceeds 100m/s, the thermal deformation should be corrected at the beginning of design due to the thermal effect in operation, so that the gear can reach a normal meshing state when working. Especially for high speed heavy duty gear. More to consider. Secondly, for the low speed and heavy duty gear such as rolling mill gear, due to the use of hard gear surface, the gear surface load coefficient increase caused by the elastic deformation of the whole gear device system has become prominent, so sometimes it is also necessary to reflect the elastic deformation of the tooth surface correction. The technology of tooth modification is an important trend in the manufacture of high power, high speed and heavy duty gear. In gear manufacturing technology.
The focus is on hard tooth surface processing, especially the development of cutting and heat treatment process of large hard tooth surface gear forgings, such as super-hard tooth cutting, inner hobbing, forming gear grinding, large modulus gear honing, elastic grinding wheel polishing, gear tooth modification, and deep sand carbon and other new processes are constantly tested and applied in production.
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