Helical gears are widely used in gear transmission of agricultural machinery products, new energy vehicles, wind power equipment and other gear transmission occasions due to their strong bearing capacity, large coincidence and smooth transmission. However, due to the influence of installation error and manufacturing error, meshing impact will occur when gear teeth mesh, resulting in vibration and noise. Diagonal modification is an effective way to reduce vibration and noise. Therefore, the accurate modeling of diagonal modified helical gears is of great significance to the calculation of meshing impact force, the load-bearing contact analysis of tooth surface and the finite element simulation analysis.
Wang constitutionalism and others first proposed the diagonal modification method, and proved that the diagonal modified helical gear has lower noise than the standard gear through tests. Jiang Jinke et al. showed through simulation calculation that the diagonal modification is more effective than the tooth profile modification in reducing vibration and noise of helical gears.
He Xiangyue found through simulation calculation based on Masta platform that diagonal modified helical gears can reduce the squealing of electric vehicles. Zeng Hong and others completed the modeling of spiral bevel gears based on CATIA reverse engineering, and imported ABAQUS through seamless interface to complete the contact stress analysis. This method can improve the analysis efficiency. Gao Xiaowei and others modeled spiral bevel gear based on CATIA and imported it into ABAQUS to complete stress analysis. The simulated stress is basically consistent with the stress calculated by Hertz contact theory, which verifies the rationality of modeling.
Gede et al. studied the method of fast and accurate modeling of standard helical gears based on MATLAB and CATIA. Tang Liangbing and others established a three-dimensional model of helical gear based on CATIA and completed the stress analysis. The test results are basically consistent with the simulation results, indicating the reliability of the modeling. Based on CATIA, Jinmeifu and others completed the modeling of helical gear with drum profile modification in tooth direction, with a maximum accuracy of 0 level. Fuentes-Aznar et al. proposed the Hermite interpolation method to realize the geometric modeling of the transition zone of the non-smooth connection tooth root.
CATIA has high accuracy in gear modeling and is widely used in practical engineering. Based on CATIA, the accurate modeling of diagonal modified helical gears is of great significance to structural design and CAE rapid analysis. In this study, first of all, the helical gear is taken as the research object, and the coordinate system of generating helical gear from the imaginary helical rack is established, and the equations of standard working tooth surface and tooth root transition tooth surface are derived. Secondly, the specific process of the diagonal modification method is given. The modified tooth surface is built by superposing the modified surface in the normal vector direction of the standard working tooth surface, and the boundary between the modified tooth surface and the tooth root transition surface is smoothed by Hermite interpolation. Finally, with the help of CATIA, the 3D reverse modeling and fitting deviation analysis of the diagonally modified helical gears are completed.