Study On Modeling And Profile Modification Of Helical Gear Based On Contact Analysis

With the Wind Turbine Generator developing towards high power, more requirements are put forward on the Increasing Gearbox of Wind Turbine Generator. Therefore, further investigation on the Increasing Gearbox's gear-driven system of Wind Turbine Generator, especially the modification technology of helical gear, is valuable to enhance its load-bearing capacity and transmission stability.This thesis does some research on the Increasing Gearbox's gear-driven system of Megawatt Wind Turbine Generator which is imported by DHI·DCW Group CO., LTD. Thesis also proposes an profile modification technology when helical gear with multi-tooth are meshing that can do a lot technical supports on exploiting High-power's Wind Turbine Generator. This thesis builds a 3D parametric finite element model of helical gear in ANSYS software and uses the contact method to analyze the loading and transmission error of helical gear. Combining the conjugate engagement principle of helical gear, a method to modify the profile of helical gear has been put forward.Firstly, this thesis introduces the finite element contact principle which provides the theoretical support to the contact analysis of the engaging load of helical gear on the Increasing Gearbox. According to the engagement principle of involutes gear, thesis deduces the involutes curve equation, the involutes curve helicoids equation, the root transition curve and the contact ratio equation and then uses the ANSYS Parametric Design Language to build the 3D parametric finite element model of helical gear in ANSYS software. By combining with SQL Server, the grid of the contact surface of finite element model is refined and the helical gear tooth is modified. The contact pair of contact analysis is established parametrically.Secondly, the loading distribution and transmission error of single and double helical gear teeth mesh process is calculated by the ANSYS finite element contact analysis, by comparison of the analysis result, the influence of contact method and parameters to the result is existent Then thesis analyzes the differences between Hertz and ANSYS calculation, justifies the accuracy of the modeling method.Finally, the reason of transmission error sudden change is analyzed according to the helical gear conjugate engagement principle and thesis proposes the scheme of gear tooth profile modification. Then the profile modification of helical gear is optimized by the finite element contact method so as to make sure the optimum modification amount and the strength and transmission error of helical gear is compared before and after profile modification. The analysis of profile modification shows that the transmission error distribution of helical gear has great improve after profile modification and the transmission quality of helical gear has been great enhanced. It is also showed that the profile modification of helical gear using finite element contact analysis in the thesis is feasible.The research on the profile modification of Increasing Gearbox is of great value and significance for a further research of gear-driven kinematical capability and integrated tooth modification.