Forming Control And Process Technology Research Of Tooth Parts Precision Cold Roll-beating

The manufacturing level of tooth parts is an important embodiment of the mechanical industrial level of a country,and the near-net forming process represented by precision cold roll-beating is the research focus and trend of tooth manufacturing technology.In the last ten years,new techniques and methods have been employed by domestic and foreign scholars for the research of high speed cold roll-beating,and a lot of achievements have been put forward.These achievements changed the traditional research methods of cold roll-beating,which were mainly investigated by trial production without theoretical guidance.But the research depth of forming mechanism of cold roll-beating was still inadequate.No studies have been reported about the shape control of cold roll-beating and process technology with considerations of forming precision and efficiency,and no analytic model has been proposed for predicting the forming force of cold roll-beating efficiently.The theoretical guidance to cold roll-beating equipment manufacture and forming process research can not be provided.The dissertation is focus on the kinematics and mechanics of cold roll-beating,and carries out researches on the forming technology of cold roll-beating,including shape control,determination of mechanical parameters and process parameters.Based on above researches,the dissertation investigated the forming method,forming process and forming force of odd-tooth parts cold roll-beating.The research is mainly based on the method of theoretical analysis and calculation combined with experiments,including the method of mathematics model establishment,traditional analytical methods of plastic mechanic and finite element method.The conclusions are proved each other by these methods.The mathematics model of cold roll-beating forming curves is established,and the interference is characterized.The continuous indexing cold roll-beating is proved to be generating process,and the mechanism of interference is revealed,and the distribution of interference in the profile and tooth width is calculated.The theoretical direction for tooth profile correction of roller is provided.The setting-angle of roller is calculated by traditional method and interference analysis method,and the limitation of traditional method is pointed out.The dissertation considers that the determination of setting-angle should be based on the comprehensive analysis of profile errors and tooth width errors.The tooth width errors of continuous indexing cold roll-beating are calculated,and the method to decrease the tooth width errors is provided.The method of shape control is studied with aim at forming defects control of cold roll-beating.The finite model consistent with the practical process is established,and the uplift process of gear is studied,and the mechanism of concave crown,fins,arched gear and the tooth surface waviness are revealed.The transverse plane radius of gear blank is calculated,and the modified method is studied.The errors of tooth surface waviness are calculated,and the experiment of cold roll-beating is conducted,through which the errors of tooth surface waviness are measured to be approximate to the theoretical value.Finally,the method to reduce the errors of tooth surface waviness is proposed.The efficient prediction analytic model for forming force is given for determination of the force and energy parameters of cold roll-beating.The characteristics of deformation zone is studied,and the results show that the parameters of deformation zone change constantly and the cold roll-beating belongs to cumulative increment deformation process.The single cold roll-beating process is divided into infinite number of cold rolling processes.The specific pressure,radial force and tangential force of cold roll-beating are calculated,and the tangential force is proved to be relatively small and less influence on the determination of the force and energy parameters of cold roll-beating.The dissertation put the emphasis on the radial force of cold roll-beating,then the parameters of analytic model are modified and verified by the finite element method.The experiment for cold roll-beating forming force measurement is carried out by the improved horizontal milling machine,and the measurement results and the calculation results are in good agreement.The influences of process parameters and gear blank material on the forming process are studied,considering the production efficiency and economy.The finite element software DEFORM-3D is employed to study the influences of feed rates,rotating radius of roller and material of gear blank on the interference,stress conditions,forming precision and waviness errors of tooth flank,and the criterions of determination are given.The reasons for the decrease of distance between two rollers compared with root circle diameter are analyzed,and then the calculation method of decrease value is given and verified by the finite element methodThe odd-tooth parts cold roll-beating is studied in aspects of forming motion,stress conditions of gear blank,forming process,waviness errors of tooth flank and so on.Considering single roller cold roll-beating forming process,the odd-tooth parts cold roll-beating is different from the even number process due to the forming precision of two tooth flanks are inconsistent.Considering two rollers cold roll-beating process,it is more complicated,for the effects of two rollers overlapped each other,and the forming precision is relatively low.The analytic model is employed to calculate the radial force and tangential force of odd-tooth parts cold roll-beating,and the calculation results and simulation results are in good agreement.The result indicates the feasibility of odd-tooth parts cold roll-beating.