Thermal analysis of ultrasonic vibration-assisted grinding with moment-triangle heat sources

AISI 9310 steel has garnered increasing attention for its superior mechanical properties in the manufacturing of transmission gears for helicopters and accessory transmission systems in aero-engines. The ultrasonic vibration-assisted grinding (UVAG) technique is a new potential method to machine tooth surface given the periodically changing trajectory between abrasive grains and the workpiece, contributing to enhancing heat transfer and thus solving sudden burns. The accurate prediction of grinding heat and the proposal of the associated control strategy are desired to ensure the machining quality. Combined with the separation coefficient model and the chip volume distribution of UVAG processes, a new moment-triangle (MT) heat source model was established. Subsequently, comparative analyses on grinding temperature with conventional grinding and UVAG process were performed using the conditional triangular heat source model and the proposed MT heat source model. Results show that the MT heat source model has a lower prediction error with an average error of 7.13%, which is improved by 7.33% compared with that of the triangular heat source model. The prediction accuracy for the maximum grinding temperature can be raised by 13.39% when the MT heat source model is applied in place of the other one under UVAG processes. In addition, the heat source model transits from triangular into uniform heat source gradually as the ultrasonic amplitude increases, and the transition rate is positively correlated with the ultrasonic amplitude. On this basis, the desired controlling strategy is proposed to enhance the machining performance of ultrasonic grinding processes and effectively reduce heat generations during grinding by increasing the ultrasonic amplitude, reducing the depth of cut and decreasing the workpiece speed.