| Non-circular gear is a mechanism that can realize variable transmission ratio.Compared with other variable transmission ratio mechanisms,non-circular gears have the advantages of both spur gears and cams.It is easy to realize the accuracy of variable transmission ratio transmission and transmission motion,and can be flexibly designed according to the requirements of the work.Compared with straight non-circular gears,helical non-circular gears have the advantages of strong load capacity,large coincidence,compact structure and long life.It has better working performance under high-speed and heavy-load working conditions.However,due to the difficulty of design and manufacture,it is rarely used in mechanical products.This paper research on the transmission performance of helical non-circular gears,the influence of pitch curve errors on transmission performance,and error measurement.Firstly,using the gear meshing principle,the design method of the tooth surface equation of the helical noncircular gear is derived.The design parameters of helical non-circular gears are calculated in Matlab,and the change law of transmission pressure angle and coincidence of different meshing positions is obtained,which verifies the correctness of the design theory of helical non-circular gears.Using CAXA,UG and other software to build a three-dimensional model of helical non-circular gears,which lays the foundation for subsequent research.Secondly,the maximum contact stress of the helical non-circular gear pair is obtained through simulation analysis,and compared with the theoretical value,the correctness of the model is verified.Compared with the spur non-circular gear,the stress distribution of the tooth surface proves that the helical non-circular gear has a strong bearing capacity.By using ADMAS to compare and analyze the transmission performance parameters such as angular velocity and tooth meshing force of the two types of gear meshing,it is found that the transmission performance of helical non-circular gears is better than that of spur non-circular gears.Thirdly,based on the design parameters of the original helical non-circular gear pitch curve,eight sets of theoretical models with errors were designed.Through Matlab,ADAMS,ANSYS and other software,the transmission ratio,transmissionpressure angle,coincidence degree,driven wheel angular velocity,dynamic meshing force,tooth profile error and tooth surface stress distribution of each set of helical non-circular gears are obtained.The influence of design parameters on the dynamic transmission characteristics of gears is obtained through comparative analysis.Finally,the coordinates of the tooth surface data points near the helical non-circular gear pitch curve were measured on the EinScan-SP scanner.Based on the3 rd order uniform B-spline function,the actual pitch curve and tooth line were fitted in Matlab to obtain The linear fitting of the straight line and the fitting residual figure obtained the pitch curve error of the helical non-circular gear,the spiral angle error and the shape error of the tooth line.The research results of this paper show that helical non-circular gears have better transmission performance than spur non-circular gears.The pitch curve error has a greater impact on the transmission performance of non-circular gears,and its design parameters can be adjusted to optimize transmission performance.It is feasible and efficient to write a program in Matlab to analyze the errors of the coordinate points of the obtained tooth surface.Through the study of this paper,it provides a certain reference value for the transmission performance research and error measurement of helical non-circular gears. |
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