Striving for high load capacity and low noise excitation in gear design

In the design process of gearboxes, common requirements are high load capacity and low noise excitation. Reaching both goals is laborious and normally requires a trade-off. Detailed analyses of contact conditions and deformations are necessary. These should take place in an early design stage to realize a mostly straightforward design approach and prevent late design changes. Focused on cylindrical gears, the paper covers an approach starting at the first draft of a gearbox. Defining the macrogeometry of the teeth regarding load capacity calculation according to standards leads to a reasonable gear design. On that basis, the micro geometry of the teeth is specified and load distribution as well as noise excitation is calculated. The design parameters are interdependent so provisions have to be made to adjust each step on the remaining ones. Effects resulting from changing profile contact ratio under load and contact patterns not covering the whole flank have to be regarded. The beneficial effect of a modified microgeometry is dependent on the ability to precisely account for contact conditions and meshing clearances. To find an optimal solution for the competing goals of capacity and excitation, detailed calculation methods are required. To be able to apply latest research results, these are implemented in highly specialized software. The task described above is handled by using the software that was developed at the Gear Research Center (FZG) with funding by the German Research Association for Gears and Transmissions (FVA). The underlying calculation methods and analyzed phenomena are covered.