Improved PM gear rolling simulations using advanced material modelling

Abstract

The gear rolling densification of Powder Metal (PM) gears leads to better mechanical properties due to the selectively closed porosity of some hundreds of a micrometer under the surface of the tooth. The optimization of this process is critical in order to reduce the overall design time of the process and to increase the quality of the rolled gear. One way to optimize the process, tool design and gear with stock is to conduct Finite Element (FE) simulations with a plasticity material model for porous metals. The simulations should be able to predict the resulted geometry and densification, after that the opposite procedure can be conducted and by using simulations as a design tool to predict the process parameters. In this paper, FE simulations are being performed for the gear rolling densification process. The aim is to investigate how such simulations can be used to improve the quality of the rolled gear. Moreover, to identify how more advanced plasticity material models such as the anisotropic model of Ponte-Castaneda Kailasam and coworkers can help and increase the accuracy of the calculations, compared to more commonly used models such as the one suggested by Gurson-Tveergard-Needleman (GTN). Furthermore, the results from the simulations in densification and involute profile are also correlated with experimental results to validate the accuracy of the simulations. Finally, the accuracy of the simulations in densification and involute profile will define if the target of optimizing the gear rolling densification process through FE simulations is realistic.