Application of FEA in the design and TCA of cylindrical gear drives with crowned tooth geometry

Double crowning methods have been used for a long time to avoid edge contact and to reduce the noise of cylindrical gear drives. The instant contact character of such gear drives is point contact instead of line contact. The localized contact spreads into an elliptic area under load. The traditional strength calculation method based on cantilever beam with unit thickness along lead direction cannot be applied accurately. This leads to a broad application of FEA (Finite Element Analysis) in the design and the TCA (Tooth Contact Analysis) of such cylindrical gear drives. There are ample gear FEA application papers dated as early as the 1980s, but few summarize the general application principles, procedures, and experiences applied in the crowned cylindrical gear design and TCA area. With the booming of cylindrical gear markets, especially in the Mega-Watt windmill turbine industry with special asymmetric tooth profile planetary drives, FEA becomes an effective tool in strength design along with TCA for such gear designs This paper firstly lists, the TCA contents of gear design and briefly updates the current CNC grinding technologies used to generate the double-crowned cylindrical gears. Secondly, it describes the general procedures and the author's experiences of FEA application to obtain the stress results and the TCA related data such as contact pattern and transmission errors. Finally, the popular asymmetric gear drives will be used as examples to demonstrate the application of FEA to TCA. The general application principles outlined in this paper can be applied to any type of gear drive.