Tooth Surface Design And Meshing Characteristics Analysis For HGT Hypoid Gear

The hypoid gear has the advantages of small size and large reduction ratio,so it is widely used as the automobile main reducing gear,to be the key parts of the automobile driving axle.Due to the automotive industry has more and more strictly requirements on the transmission precision of drive axle reducer,bearing capacity and noise of engine transmission,this promotes the hypoid gear to the development of high precision and low noise direction.so,in order to meet the increasing requirements of engineering,it is necessary to tap the common processing methods,or to explore new processing methods to obtain high accuracy hypoid gear for improving the meshing performance of gears.The vast majority of domestic manufacturers to adopt the Gleason gear system,it has four common cutting method,respectively as HFT(Hypoid Formate Tilt),HFM(Hypoid Formate Modified),HGT(Hypoid Generated Tilt)and HGM(Hypoid Generated Modified).HFT machining method,the pinion is machined with single cutter tilt method,which can simplify tool specifications,the adjustment operation is relatively simple,and the modified method doesn't have the advantage;the gear is machined with formated method,which can simplify process and low cost,so it has been widely used in the automobile industry,but this method is difficult to keep the contact trace as a straight line,can be not very good to improve lubrication properties of tooth surface,resulting in poor meshing stationarity.HGT machining method,the pinion is machined with single face cutter tilt method,also;the gear is machined with the double face cutter generated method,which can better control the meshing performance of gears.The machining method of the pinion is the same for HFT and HGT hypoid gear,but the machining method of the gear is different,and the geometrical structure of tooth surface is also different.Because the tooth surface geometry structurethe is complex for hypoid gear,and the design of the pinion tooth surface need according to the gear tooth surface,Therefore,the tooth surface design and processing technology for HGT hypoid gears are studied systematically in this paper,and the meshing performance is all round compared with HFT hypoid gear.If HGT hypoid gear whose meshing performance is better can be used in the automobile transmission in place of HFT hypoid gear,to the automobile industry development will have the important meaning.Combining the advantages of the generated method and tilt method,in this paper,the gear meshing theory,tooth contact analysis(TCA),loaded tooth contact analysis(LTCA)and other methods are used to improve the meshing accuracy and strength condition of gear meshing,and the systematic theoretical and experimental research on the HGT hypoid gear(hypoid gear machined by HGT machining method)are done.The main results and innovations are as followings:1)Be aimed at the processing parameters directly affect the meshing performance of the hypoid gear,as well as the traditional design methods and manufacturing methods is very difficult to control the meshing quality,and the design of the machining parameters for HGT hypoid gear is studied.In this paper,a set of complete design analysis system for HGT hypoid gear is established,which based on the machining principle of Gleason hypoid gear,combining with the local synthesis method,TCA and LTCA,as well as combining with the exact strength calculation method for bending stress and contact stress.The system can be to ensure the meshing quality of HGT hypoid gear pair in the design stage through pre-controlling the first order and second order contact parameters,and the active design of tooth surface is realized.2)By adjusting the position of the reference point and the first derivative of the transmission ratio function,the edge contact of the gear pair can be avoided effectively.In the case of the same wheel blank parameters and local control parameters,the meshing performance of HGT and HFT hypoid gear(hypoid gear machined by HFT machining method)is compared,the good characteristics is achieved that the contact trace is straight of HGT hypoid gear and the long axis of contact ellipse are nearly the same size,which can effectively improve the lubrication characteristics of tooth surface for improving the meshing smoothness,but HFT hypoid gear is difficult to achieve the characteristics,proving that the generated method can better control the meshing performance than the formated method.3)Be aimed at the increasing demands of mechanical transmission in high speed and high reliability,the high degree design is done for HGT hypoid gear.With this method,machining parameters of cutter head and machine tool meetting certain requirements can be easily and quickly obtained only by adjusting the angle between the contact trace and root for making full use of the gear tooth to the coincidence degree,under the condition of constant wheel blank parameters,the contact analysis and strength calculation are done.4)The sensitivity to misalignment of the tooth surface contact pattern has become the key for the tooth surface design of the hypoid gear.In this paper,the mathematical model of sensitivity to misalignment of the tooth surface contact pattern is established firstly,and the sensitivity coefficient is calculated,then the optimization design and analysis on sensitivity is done by means of quantitative application of the perturbation method for HGT hypoid gear,the results show that the sensitivity to shaft angle misalignment of the tooth surface contact pattern is maximum,so its installation precision should be first ensured in gear design andinstallation.Also through be compared with HFT hypoid gear,it finds that the sensitivity to mounting misalignment of gear pair is effectively reduced because the contact trace is a straight line.5)Be aimed at the transmission error curve is lack of effective control in design,manufacture and inspection at present,as well as characteristics of variable working conditions of the car,the optimization design of the loaded transmission error for HGT hypoid gear is proposed.The amplitude of the loaded transmission error curve is optimized,the results show that the amplitude of the loaded transmission error is reduced,and the purpose of reducing vibration and noise is reached;it also finds that the coincidence degree,geometrical contact transmission error curve of conversion points of the amplitude and bearing between the transmission error curve amplitude of the gear pair have important relations and rules,the discovery has important significance to study the meshing characteristics of the gear pair.And the dynamic characteristics after optimized of HGT and HFT hypoid gear are compared under the same condition of wheel blank parameters and local control parameters.It finds that the vibration characteristics of HGT hypoid gear under the same conditions are better than that of HFT hypoid gear.6)On the basis of the above theoretical study,the experiment is carried out on a pair of main reducer hypoid gear used on a mini vehicle drive axle.HGT and HFT methods were used to process the gear pairs and the rolling test was carried out,taking into account the error and deformation factors may exist in the actual machining process,the results of the test and TCA simulation are basically consistent,verifing the reasonable design of processing parameters and the correctness of the meshing performance analysis;At the same time,the vibration test was carried out,by comparison,it finds that the vibration characteristics of HGT hypoid gear are better than that of HFT hypoid gear.The design methods and conclusions of this paper are applicable to all HGT hypoid gears,it has a positive significance for improving the design and manufacture level of the hypoid gear and promoting the application of HGT hypoid gear in the industry;it has important theoretical and practical significance for promoting the development of national automobile industry and improving the competitiveness of the independent brand automobile.