Distortion Minimization of Bevel Gear Press Quench Process using Computer Modeling

Press quenching is used to harden and reduce distortion of gears with large sizes or thin-wall sections. For carburized gears, controlling distortion is critical because only a limited amount of the carburized case is allowed to be removed. In comparison to immersion oil quenching, the press quench process involves more process parameters due to the thermal and mechanical effects from the tooling on the parts and is mainly experience based, with iterative trials needed before obtaining an acceptable process. Simulation provides a means for understanding the effects of tooling and process parameters on distortion, which can be used to optimize the process and tooling design. In this paper, press quenching of a bevel gear made of carburized AISI 9310 is modeled using the commercial heat treatment software DANTE. Radial shrinkage and taper of the inner diameter are the main distortion modes, and the modeling results show that the expanders are not effective in controlling the distortion of the inner diameter of this gear. Based on the simulation results, an effective method using an oversized plug is proposed to replace the expanders. The plug configuration is further optimized to reduce the taper distortion of the inner diameter of the gear.