Optimization of heat treatment process of SCM420 steel planetary gear for industrial robot

doi:10.13251/j.issn.0254-6051.2021.03.021

Abstract

Abstract: Aiming at the heat treatment distortion problem of SCM420 steel planetary gears used in industrial robots, a modified normalizing process was used to adjust the preparatory microstructure before carburizing, and then the gear distortion during carburizing and quenching was effectively controlled by using various measures including reasonable loading scheme, cooling method, and stepped heating process during carburizing. The results show that after the modified normalizing process, a uniform ferrite+pearlite microstructure can be obtained with a hardness of 170 to 180 HBW. And after the carburizing quenching and tempering, the surface hardness, core hardness and effective case depth of the planetary gears with mass production are 59.74 HRC, 40.44 HRC and 0.530 mm, respectively. The grade of martensite of carburized layer is level 1, and that of the retained austenite and carbides are level 1-2, and that of the core microstructure is level 1-2. The gear precision, plane warping, tooth groove amplitude and toothed ribs all meet the technical requirements.

Key words: SCM420 steel, planetary gear, heat treatment distortion, normalizing, carburizing quenching and tempering

CLC Number:

TG156.9

Yin Heping, Yin Minjie. Optimization of heat treatment process of SCM420 steel planetary gear for industrial robot[J]. Heat Treatment of Metals, 2021, 46(3): 104-108.

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