Targeted micro geometry scattering for NVH optimization of cylindrical gears in continuous generating grinding

Abstract This report presents a new method for calculating and designing grinding worm geometries for continuous generating grinding in order to realize targeted micro geometry scattering on gear flanks. The method uses the idea to transfer the ideal micro geometry onto the worm topography utilizing a reversed rolling calculation. First, the reversed calculation of the grinding worm flanks is carried out by gradually breaking down a specified gear geometry with varying micro geometries into individual profile cross-sections. Afterwards, these profile cross-sections are transformed into a grinding worm geometry whose starts can manufacture different modifications. The grinding worm topography is calculated using an exemplary application in which targeted micro geometry scattering on a cylindrical gear is reverse generated onto the generating profile and then onto the grinding worm body. The example serves to verify the method. The calculated grinding worm geometry is used for forward generation of the flank geometries and kinematic differences between the nominal and actual geometry of the gear flanks are shown as a comparison. A key advantage of this new approach is the avoidance of periodically repeating ripples on the tooth flanks, which occurred when using previous approaches to manufacture targeted micro geometry scattering in the generating grinding process due to differently dressed grinding worm starts. The new approach uses a dressing gear for shaping the grinding worm geometry. It achieves an improved NVH behavior of the gear pair concerning the tonality through varying flank modifications by utilizing the topographically shaped grinding worm starts. This was verified as part of a quasi-static tooth contact analysis in which the derived grinding worms were used to generate replica of dressing gears and investigate the acoustic excitation behavior. The simulation results show significantly reduced levels of the transmission error in the gear mesh orders and at the same time lowered tonal noise components, which indicates a subjectively more favorable noise behavior.