Finite Element Analysis And Process Research On Multi-step Precision Forging Of Straight Bevel Gear

Precision forging of straight bevel gears refers to the forming technology that can achieve the gear precision requirements after the gears are forged,slightly trimmed or no longer trimmed.The technology can prevent metal fibers from being cut which guarantee the mechanical properties of the workpieces,and also saves materials which result in high production efficiency.In recent years,with the rapidly growth of the output of the automobiles and agricultural machinery,the demand for gears for transmission parts is growing year by year.Competition among companies have become sharply.The technology of gear precision forging has been used massively due to it can both improve the production efficiency and save materials.But,it still existed many problems,such as lower efficiency and flash when compared with milling process.In the actual production of the enterprise,the combined technology of forging and milling were also used in many companies,which firstly performed the precision forging process and then milling in order to make the workpieces meet the precision requirements.However,in the milling process,machining time is so long which result in longer time in the whole machining gear process.In order to solve these problems,domestic and foreign scholars have used simulation software to do research on gear tooth profile process and mold,but the influence of forming factors on gears,the influence of temperature on mold wear and the precise design of molds have yet to be studied.The straight bevel was selected as the research object in this paper,and the 3D model of the straight bevel gear was established using UG.The precision forging die corresponding to the straight bevel gear of this model was designed,according to the precision forging technical requirements in the one-step forming process and the 2D parts drawing of the straight bevel gear.On the theoretical basis of metal forming and the Archard wear model,the effect of high temperature on hardness was researched.Factors which have a greater resistance to metal forming were analyzed during the process of metal forming,the horizontal value according to the characteristics of each factor was selected,and the orthogonal simulation scheme was designed.The finite element simulation of the research object was carried out,by the metal forming simulation software DEFORM-3D,while the optimal machining parameters of the workpiece forming were determined by orthogonal simulation.Based on the analysis of the simulation results using optimal forming parameters,the corresponding law between metal forming resistance and metal fluidity in forming process was found.By analyzing the forming resistance of straight bevel gear and the corresponding law of metal flow,one-step forming process was adjusted,in addition,a multi-step forming process without flash processing was designed as well.Molds corresponding to different forming processes were designed according to the multi-step forming process mentioned above.The finite element simulation analysis of straight bevel gear forming was carried out to verify the feasibility of multi-step forming process,which used optimal processing parameters in the forming process of metal straight bevel gears.According to the finite element analysis results of the workpiece and mold as well as the step forming analysis of straight bevel gear,the surface coordinate change of the workpiece was compensated to the corresponding mold,then the precise mold was finally designed.The straight bevel gear was tested using designed multi step forming process technology and the accurately designed mold as well.The research results showed that the multi-step forming process could solve the flashing problem generated in the precision forging process of gears,and the precision of straight bevel gear could be achieved only by precision forging.Compared with the one-step forming,the wear amount and the cumulative wear rate of the molds at each stage of the process are significantly decreased,and the mold life is significantly improved.The processed straight bevel gears have been measured to meet the design accuracy requirements.At present,the multi-step forming process has been applied successfully in Yancheng Jingangxing Precision Forging Co.,Ltd.