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2021

Design Benchmark Selection and Preheat Treatment Method for Bevel Gears

Generally speaking, the principles of the design benchmark selection of bevel gears are: the principle of datum coincidence, the principle of datum unification, the principle of self-reference, the principle of mutual reference, the principle of easy clamping, and so on. Generally speaking, when designing bevel gears, they will be developed and designed in strict accordance with these principles. After the design benchmark is set, they will be manufactured. Today, we are mainly talking about the preheating treatment of bevel gear blanks in manufacturing.
Suitable bevel gear blank preparation heat treatment can not only obtain a more uniform microstructure, but also eliminate stress and reduce distortion for the final heat treatment.
1, positive fire high temperature tempering process is suitable for high hardenability of low carbon medium alloy steel, such as 22CrMnMo, 20CrNiMo, 18CrNiWA and 20CrNi3, etc., can be obtained hardness 170-228HBW, gold phase for ferrite and ferrite matrix distribution of tempering sothosome.

2. The simple isothermal normalizing process equipment adopts two trolley-type resistance furnaces. The process route is that the tooth blank is heated at high temperature (940-960 ℃) in furnace 1-discharged after heat preservation-air cooling for an appropriate time-enters furnace 2 for isothermal (550-650 ℃)-discharged and air cooled. The isothermal temperature and time are determined according to the austenite isothermal transformation curve of the tooth blank steel to obtain normal normalizing tissue. This process is suitable for steels with high hardenability and easy to produce granular bainite, such as Cr2Ni4Mo steel, 20Cr2Ni4, 20CrMnTiH, 20MnCr5, 16MnCr5 and 22CrMoH steel, with hardness of 156-200HBW and metallographic structure of pre-eutectoid F pseudo-eutectoid P, but the effect of eliminating banded structure is not ideal.