Research On High-Speed Dry Hobbing Cutting-Force-Induced Geometric Errors Of Machine Tool And The Accuracy Of Gear

Gear hobbing is the most efficient and widely applied method in the tooth profile machining methods.High-speed dry hobbing is more efficient and green,however,due to the high-speed dry hobbing process,cutting fluid is not used for cooling and lubrication.The key problems of tool wear,tooth surface accuracy,machine tool force and thermal deformation are closely related to the technological parameters of gear hobbing.Further research is needed on the basis of traditional hobbing cutting theory.In this context,with the support of projects as the Key Program of National Natural Foundation of China(51635003),relying on the experimental equipment conditions of the State Key Laboratory of Mechanical Transmission of Chongqing University and Chongqing Machine tool(Group)Co.,Ltd..Research on high-speed dry hobbing cutting-forceinduced geometric errors of machine tool and the accuracy of gear in this paper.A complete mapping relationship of “cutting force-machine tool geometric errorsworkpiece errors-compensation” was established.The purpose of this study is to predict the effect of hobbing cutting force on the accuracy of gear manufacturing,provided theoretical basis for error control and compensation of gear hobbing machine.Firstly,the high-speed dry cutting hobbing machine as the research object,and based on the principle of homogeneous coordinate transformation,the cutting force model and the geometric error reconstruction model were established.Cutting force model converts hobbing tangential force into cutting force along each coordinate axis of machine tool coordinate system.The number of parameters needed in the error estimation can be effectively reduced by using geometric error reconstruction model.The direct expression of relative pose error between hob and workpiece was realized.Secondly,the finite element analysis of the machine was completed.So,the geometric error value of the key parts of the machine tool under the action of cutting force was obtained.And a quantitative mapping relationship between the cutting force and the pose error of hob and workpiece was established.Then,According to the engagement features of the conjugating surface and the principle of two-degrees-of-freedom hobbing,the meshing equation was deduced and the force-induced errors of the system were mapped to the normal errors of gear surface.In this way,the mapping relationship between different kinds of force-induced errors and hobbing precision can be obtained.Then,the theoretical tooth surface and the real tooth surface under the influence of force-induced errors were respectively calculated by using a numerical simulation method.It provides a theoretical basis for force error compensation.Finally,according to the relative position relationship between theoretical tooth profile and error Tooth profile,a geometric error compensation model for force induced machine tool was established.It can directly solve the optimal compensation size and compensate the error of tooth thickness effectively.Developed numerical simulation of visual interface,it can provide help for gear error analysis.According to the research contents of this paper,an experimental testing system was built,the finite element analysis and numerical simulation of hobbing machining were verified.