| The automobile gear box is developing towards high load capacity,low running noise and compact design,and the requirement of gear precision is more and more strict.In particular,in order to meet the requirements of noise and vibration,the topological modification technique of gears has been highlighted.Generally,the topological modification is the transverse profile and the flank line modification,which can effectively improve the meshing performance of gears and reduce noise and vibration.At present,the worm wheel gear grinding machine is mainly used in the precise processing of the automobile transmission gear,which has the characteristics of high efficiency and high accuracy.However,there is a principle error when the worm wheel grinding machine is engaged in the topological modification gears,resulting in the tooth surface flank twist,which seriously restricts the further improvement of the gear accuracy.Therefore,how to grinding the precision gear which is the same as the theoretical design has become a difficult problem for the gear industry.This paper analyzes the topological modification gears tooth surface error of continuous generating grinding,proposed a method to reduce machining error from the angle of design,is of great significance to further improve the accuracy of precision gear.The main contents of this thesis include:(1)The equation of topological modification tooth surface is deduced and a 3D model is established.On the basis of involute gear,from the view of transverse profile modification,the equation of transverse profile modification tooth surface is deduced.From the view of flank line modification,the equation of flank line modification tooth surface is deduced.On these bases,the tooth surface equation of topological modification gears is established,and the 3D model of the modified gear created by Matlab and Solidworks software.is simulated.(2)The method of topological modification in continuous generating grinding process is analyzed.The structure and machining principle of worm wheel grinding machine are introduced.According to the meshing relation between worm wheel and gear,a model for calculating the profile of tooth contact trace and worm wheel profile are established.According to flank line modification curve,the grinding path of worm grinding wheel is designed by the form of additional motion.(3)A calculation model of tooth surface flank twist is established and the and the method of tooth surface flank twist reduction is put forward.The mechanism of the continuous grinding error of the topological modification gear is analyzed,The tooth surface flank twist is calculated from the tooth profile error of the upper and lower surfaces of the gear.Meanwhile,the curve of the flank line modification is optimized by the combination of two curves,so as to effectively reduce flank twist.(4)The von Mises stress and contact pressure of the gear before and after modification are analyzed by contact finite element method.The change of maximum von Mises stress and contact pressure of transverse profile modification and standard involute gear during meshing and meshing are compared;The contact pressure distribution between the contact gears of the flank line modification and standard involute gear is compared.(5)Gear machining experiments are carried out and the meshing noise and vibration of the gear pair are detected.Taking an automobile gear as an example,the worm wheel grinding machine is used to do the processing,and the results of tooth surface flank twist before and after the reduction are compared.The noise and vibration experiments are carried out on a multipurpose transmission tribotester,and the reduction of noise and vibration is analyzed. |
