Research On Longitudinal Correction Of Helical Gear In Gearbox For Wind Turbine Generator

With the development of wind turbine generator towards higher power, more requirements are put forward on the reliability of increasing gearbox. Further research on gearbox's drive system for wind turbine generator, especially on gear correction technology, is significant in enhancing gear's load-bearing capacity and prolonging its life.In this thesis, intermediate stage of gearbox's drive system for megawatt wind turbine generator was studied and schemes of longitudinal corrections (crowning and helical angle correction) for helical gears were proposed by using finite element analysis method and adopting longitudinal correction theory, then the effects of longitudinal corrections were verified through simulation.Firstly, finite element analyses were performed separately on the two gear shafts of intermediate stage. Then bending deformation of shaft centerline and torsional deformation of gear were acquired from the analyses through APDL programming, MATLAB programming and ANSYS's PATH function.Secondly, after parameters needed were figured out on basis of longitudinal correction theory, crowning and helical angle correction were carried out in CAD. Then contact analysis of gear shafts after correction was performed. Moreover, mesh force was acquired and compared with that got from contact analysis of gear shafts before correction. The comparison showed that mesh force was distributed more uniformly and one side contact was avoided after longitudinal correction. Therefore, the schemes of crowning and helical gear correction used for gears of intermediate stage were feasible.Thirdly, through contact analysis of interference fit on hollow shaft, bending deformation of shaft centerline and torsional deformation of gear caused by interference fit were obtained, and compared with deformation got from analysis without considering interference fit. The comparison showed that interference fit has a larger impact on bending deformation of shaft centerline than on torsional deformation of gear. So it is necessary to include the deformation caused by interference fit in crowning while it is unimportant to include that or not in helical angle correction.Finally, the impacts of parameters of interference fit on connection strength were studied and some suggestions on design of interference fit were given, that chamfers should be made on the hole of interference fit to reduce stress concentration and the affects of friction coefficient change should be considered when interference magnitude is large.