Analysis of root residual stress and total tooth profile deviation in hobbing and investigation of optimal parameters

Abstract

The residual stress(RS) at tooth root from machining significantly affects bending fatigue performance of gears. Aiming at minimizing the root RS while ensuring the gear accuracy during hobbing process, the integrated method of numerical simulation, response surface, Non-dominated Sorting Genetic Algorithm-II (NSGA-II), principal component analysis, entropy weight calculation and combined weighting of game theory was adopted. Firstly, a simulation step for root RS in hobbing was proposed to obtain the incidence relation between process parameters and root RS, aiming to provide a reference for preselection process parameters in subsequent experiments. Then, the response surface experiment was designed to create regression models and analyze interaction effect of process parameters on total tooth profile deviation and root RS. Then, NSGA-II was adopted to optimize total tooth profile deviation and root RS, acquiring Pareto frontier solution set. Finally, the optimum process parameters of hobbing were determined by the method of principal component analysis, entropy weight calculation and game theory combination weighting. The research result indicates that hob speed seriously affects total tooth profile deviation and root RS. The optimal total tooth profile deviation and root RS are 10.31 µm and 131.13 MPa. The optimum hob speed, axial feed speed and radial cutting times are respectively 766.13 r/min, 1.888 mm/min and 3.58 times. The effectiveness of optimization method is verified by experiments, and the error is within 10 %. This research can effectively reduce the root RS from machining under the premise of ensuring machining accuracy, and provide a significant reference for improving the bending fatigue performance of gears.