| As a basic component in the driving of intersecting axes, spiral bevel gear (SBG) has been widely applied in the transmission system of automobiles, airplanes and many other machine tools since it has many advantages such as the big overlap ratio, the stability, lower noises and high loading capacity. The application of SBG in automobiles is particularly wide, and every transmission of automobile contains a pair of spiral bevel gear at least. The manufacturing accuracy and quality of SBG have direct influence on the efficiency, noise, precision and lifespan of the automobile transmission. A large number of studies show that the service performance has been improved and the lifespan has been increased by improving surface quality of gear. Finishing provides an effective method for improving gear surface quality and then improving gear accuracy.Pulse Electrochemical Finishing (PECF) and Electrochemical Mechanical Finishing (ECMF) are two kinds of nontraditional finishing process, which could finish the workpiece surface with any hardness efficiently and have been used as the finishing process of various parts. So, applying PECF and ECMF to SBG tooth surfaces is of great significance to the improvement of its quality.In PECF, the variation of workpiece surface micro-topography has been studied. Based on the Faraday's law, the theoretical models about the variation of the surface roughness and the removal thickness with the finishing time have been developed. The validity of developed models has been verified through experiments. The effects of processing parameters on surface profile have been investigated and the smoothing mechanism of PECF is explained. In ECMF, the characteristic of passive film formed on the workpiece surface by anodic dissolution is the key for workpiece surface smoothing in ECMF. The thickness, resistance and composition of the passive film have been determined through experiments in order to make a further analysis about the effects of passive state on the anodic smoothing.Based on the above discussion and according to the structure features of SBG, the applications of PECF and ECMF to the SBG are discussed.In the study of PECF's application to the SBG tooth surfaces finishing, different application schemes are compared. It has been found that PECF with a tooth profile shaped cathode is a preferable scheme. Combined with the principle of PECF, an experimental setup for the SBG tooth surfaces finishing has been established based on Gleason No.16 cutting machine. The experimental results show that the SBG tooth surface roughness Rz is reduced from 7.13μm to 4.32μm. According to Din3965, the precision of the SBG convex side is improved form 10 to 8, and the precision of the SBG concave side is improved from 9 to 7. Because the PECF is complicated and non-linear process, least square support vector machine (LSSVM), an intelligent model is adopted for optimizing the processing parameters. The results indicate that the model has reasonable accuracy.In the study of ECMF's application to the SBG tooth surface finishing, an experimental setup for the SBG tooth surfaces finishing has been established based on ZX50F vertical milling machine. The cathode design, the cutter head design, the gear fixture design and the parameters adjustment of vertical milling machine are especially studied. The experimental results show that the SBG tooth surface roughness Ra is reduced from 1.6μm to 0.05μm and the precision of the SBG is maintained.The conventional grinding methode can be insteaded by ECMF in tooth surfaces finishing of SBG. The tooth surfaces after ECMF are uniform and smooth, which has many advantages such as small friction coefficient, high contact rigidity and high fatigue resistance. ECMF can improve the lifespan and decrease the meshing noise of SBG pair. In order to improve the efficiency and lifespan of transmission system of automobiles, airplanes and many other machine tools, the quality of SBG products should be improved.
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