| 摘要 |
PURPOSE: A method for heat treatment of an annulus gear for an auto transmission is provided to reduce the time for heat treatment by enabling a large amount of carburization quenching. CONSTITUTION: A method for heat treatment of an annulus gear for an auto transmission comprises the steps of: preheating a material to 340°C-360°C, regulating the internal temperature of a heat treatment furnace to 740°C-760°C, loading the preheated material in the heat treatment furnace, raising the temperature to 840°C-880°C at a rate of 1.5°C-2.0°C/minute, maintaining a vacuum condition at the raised temperature, periodically supplying acetylene gas and nitrogen gas for an hour and twenty minutes, controlling the carburization effective depth, where the concentration of carbon becomes 0.35-0.4 wt%C, to 0.2-0.4mm, transferring the material to a cooling chamber and regulating the speed of a cooling fan with helium gas of 4-8bar to RPM of 40-70%, and performing quenching. [Reference numerals] (AA) Vacuum carburization(860°C, 80minutes); (BB) Preheating; (CC) 6bar gas quenching |
