The conventional carburizing heat treatment gives annulus gears of auto transmission high surface hardness and stiffness. But, it gives also undesirable distortion by the heat treatment that causes planetary gear noise. To reduce distortion by heat tr...
The conventional carburizing heat treatment gives annulus gears of auto transmission high surface hardness and stiffness. But, it gives also undesirable distortion by the heat treatment that causes planetary gear noise. To reduce distortion by heat treatment of annulus gear, we apply nitriding heat treatment for annulus gear. The heat treatment deformation of nitriding is smaller than that of carburizing. Also considering the difference of the gear flank deformation caused by each heat treatment methods, we modified the tooth form of pinion to suit the changed shape of annulus. The results of bench noise tests shows that gear noise of auto transmission is reduced with dispersion improvement.