Design of pure rolling cylindrical gears with circular arc tooth profile in the normal section

ObjectiveIn order to study the active design method of normal circular arc tooth profile pure rolling cylindrical gears based on meshing line equations, to gain a deeper understanding of the meshing characteristics of this new type of gears, including contact marks and non load transmission errors, and to better grasp the effects of center distance error, cross axis error, and cross axis error on the meshing characteristics of normal circular arc tooth profile pure rolling cylindrical gears with tooth profile modification, a series of studies were conducted.MethodsThe transverse active tooth profiles of the gear and pinion were deduced according to the circular arc tooth profiles in the normal section. The entire transverse tooth profiles were combined with the active tooth profile and a Hermite curve as the fillet, which smoothly connecting each other at the connecting point in the transverse section. The whole tooth surfaces of the gears were formed by sweeping the entire transverse tooth profiles along pure rolling contact curves of the pinion and the gear, respectively. The basic design parameters, tooth surface equations, and mathematical models for gear drives were established for tooth contact analysis. Besides, the micro-geometry modification of lead modification of parabolic crowning was applied to the pinion tooth surface to compare the meshing characteristics.ResultsThe results of TCA with and without micro-geometry modifications verify the design idea of pure rolling meshing that all the centers of contact patterns lie on the pitch of the tooth surfaces to realize the transmission of pure rolling meshing. The parabolic function of unloaded transmission errors can be realized according to a parabolic crowning of the pinion tooth surface in longitudinal direction to absorb the noise and vibration caused by misalignment errors. The separability of the center distance is demonstrated by the pure rolling cylindrical gears with circular arc tooth profile in the normal section. However, it is proven to be more acutely sensitive to the crossed shaft installation errors. The fundamental basis for the subsequent in depth investigations into stress analysis and loaded transmission errors is established.