| Spiral bevel gear is widely used in aerospace,automobile and precision machine tools and other fields due to its strong bearing capacity,smooth transmission,small noise,large speed reduction ratio and small sensitivity to installation error.It is of great importance to accurately calculate the coincidence degree,transmission error and tooth strength of spiral bevel gears in predicting gear transmission performance and reliability.The tooth surface and working condition of spiral bevel gears are complicated so it is nessesary to modify the tooth profile and tooth surface to improve the contact area of the tooth surface,to prolong the life of the gear,to reduce the transmission error and noise and to eliminate the interference as well as the concentrated stress.This paper focuses on the geometric modeling of spiral bevel gears and the calculation method of bending and contact strength.The results of the calculation were tested and verified by finite element method and experiment.The main contents are as follows:(1)The geometric model of spiral bevel gears was established on the basis of differential geometry and generating principle.The equation of the tooth surface and the tooth root transition surface were derived.The coordinate value of the tooth surface was obtained by MATLAB programming,and the curve and surface of the discrete points were fitted by CATIA to obtain the precise geometric model of the spiral bevel gear.(2)The finite element static/dynamic contact analysis models for the spiral bevel gear with standard and modified tooth profile were established.The meshing characteristics and mechanical property such as coincidence degree,transmission error,contact strength and bending strength were analyzed by commercial finite element software ABAQUS,and the influence of tooth profile modification on tooth strength was also studied.(3)The work calculated the bending and contact strength of spiral bevel gears using finite element method,whose results were verified by strength standard.Experimental load was applied to dynamic contact analysis model to calculate the root bending strength and contact strength of tooth surface.The results of finite element calculation were verified by ISO standard and AGMA standard,and the influence of load,speed and friction force on the tooth strength was analyzed.(4)Tooth root bending stress and contact pattern were measured.The root stress of spiral bevel gear was tested by NI test system and Labview software platform,which was compared with the results of contact analysis using finite element method and thetones according to gear strength standard.The imprinting pattern measurement was carried out and compared with the contact area obtained by finite element contact analysis. |
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