Characteristic Analysis of Carburized Quenching Processes for Bevel Gear of Automobile Driving Part

Abstract

The mechanical properties of automobile bevel gears manufactured by carburized guenching process are evaluated by using a finite elements method. The gear teeth of super, helical, and warm gears typically have constant cross sections and the same module, which results in the same frictional wear and stress. Bevel gears, however, are of a cone shape and thus the cross section of gear tooth change in the axial direction. As a result, the hardness after heat treatment depends on the axial location of the gear tooth. Hardness distribution due to the non-constant cross section causes gear abrasion or damage. It is difficult, however, to measure the hardness in threedimensional way through experiments. Hence, this study attempts to simulate the carburized quenching process through a numerical analysis in order to interpret the three-dimensional heat-treatment effects. The analytical results include variations of each structure, hardness, temperature over various sections depending on the cooling rate. To verify this approach, the gear used in the experiment was designed based on the same condition of the analytical model. The Carburized Quenching was carried out and the characteristics of carbon penetration, micro-structure and surface hardness were investigated by means of SEM and EPS. The theoretical results were compared with experimental results to verify the analytical method for Carburized Quenching. Keywords: Automobile, carburized quenching, finite element analysis, gear, heat treatment.