Research On Cold Extrusion Forming Technology Of Outer Gear Hub Of An Automobile Clutch

With the rapid growth of the number of domestic cars,the demand for automotive transmissions is also increasing.Clutch outer gear hub is one of the core parts in automobile transmission.Its complex shape,precise size and difficult machining has been the hotspots of experts and scholars at home and abroad.In the early 19 th century,the main processing methods of clutch gear hub were casting and machining,with low production efficiency,large energy consumption and poor mechanical properties of parts.Cold extrusion is a promising manufacturing technology,which has the advantages of high machining efficiency,low material consumption and good mechanical properties of parts.However,due to the problems of the cold extrusion forming technology of the clutch outer gear hub,such as the large forming force,the difficult filling of the tooth shape,the low service life of the die,and the inaccuracy of the forming accuracy of the internal spline,the popularization and application of the cold extrusion technology in the processing of the automobile clutch outer gear hub are seriously hindered,and the research and solution of these problems become the top priority.According to the principle of metal plastic forming and the structural characteristics of the parts,the forming process of drawing,finishing round + hole turning,cold extrusion internal spline and upsetting extrusion step were proposed in this paper.Based on the rigid plastic theory,the forming process of the outer gear hub was simulated by using the finite element analysis software DEFORM.The flow characteristics of the metal in the forming process of the blank preparation stage and the influence of the main process parameters on the forming load and forming quality of the inner spline in the cold extrusion forming process were analyzed.The multi-objective optimization of internal spline cold extrusion process parameters was carried out by the optimization method of finite element method,response surface method and genetic algorithm,so as to determine the best combination of process parameters.Finally,the cold extrusion forming process of the internal spline of the outer gear hub of the clutch(cold extrusion of the internal spline and upsetting of the step)was tested,and the size and hardness of the extrusion parts of the outer gear hub were tested.The test results showed that the outer gear hub of the clutch could be extruded by adopting the cold extrusion process.