Process Analysis And Numerical Simulation Of Closed-die Precision Forging For Cynchromesh Gear Hub

Cynchromesh gear hub is one of the important parts in the automobile gearbox,it plays the role of meshing when the gears of two different speeds reach the same speed.Cynchromesh gear hub is a structural complex gear,and the main production mode of it is open-die forging and powder metallurgy.The open-die forging method has the problems of low material utilization,high production cost and long production cycle;and the powder metallurgy method has the defects such as low product strength,poor mechanical performance,high development cost and unstable production.In order to follow the development of modern industrial technology and improve market competitiveness,we have analyzed of all kinds of forming process of gear at home and abroad,then we put forward a new type of synchromesh gear hub forming scheme,namely hot forging + cold push compound forming process.In this paper,through the study of the new forming process plan,we have drawn up the technology road map.Through the comparison and analysis of the advantages and disadvantages of the one-way extrusion forming process and the two-way extrusion forming process,we have determined the two-way extrusion forming process.Based on the structure size of the synchromesh gear hub,we established the geometrical model and the finite element model for simulation analysis.In this paper,Deform-3D finite element software is used to simulate the process of hot precision forging and cold extrusion.And then,the effective strain distribution,effective stress distribution,flow velocity field,temperature field and the load-stroke curves are investigated.We find that the type of synchromesh gear hub forming scheme is feasible.Using single factor rotation method and according to the results of numerical simulation,we have compared and analyzed of the influence of mold preheating temperature,extrusion speed and friction coefficient on forming force load and final forging temperature when hot precision forging,and we also have compared and analyzed of influence of gear tooth size and extrusion speed on forming forceload when cold push.Finally,we determine the optimum forming process parameters.The result showed that the forming quality of forging was good and the load of forming force was reduced under the optimum forming process parameters.