Research On Cold Extrusion Forming And Precision Control Method Of Internal Spline Of Gear

As an important part in the transmission system,the gear is one of the most basic parts for transmitting motion and power.Because of its advantages of large transmission load,good meshing quality and low noise,it was widely used in the industrial field.Since the cold extrusion process had the advantages of saving raw materials,improving production efficiency and reducing production costs.At present,some gear manufacturing companies at home and abroad try to use this process to replace traditional processing technology to manufacture gears.Because the gear studied in this topic is a sun gear with two splines and internal teeth,its shape is relatively complicated.There were technical difficulties in cold extrusion forming of internal and external teeth,such as excessive forming force,incomplete filling of tooth shape part,low die life and difficult to control forming accuracy,which made the cold extrusion technology greatly limited in the forming of sun gear.In this paper,three kinds of cold extrusion forming schemes were designed according to the structural characteristics of gears with internal splines and external teeth.Through the numerical simulation analysis results,the process scheme of forming internal splines first and then external teeth was determined.Through numerical simulation analysis,the metal flow law of gear in cold extrusion process was obtained,and the influence law of different blank inner hole diameter,mandrel sizing belt length and concave die half angle on cold extrusion forming load,forming quality and internal spline forming accuracy was obtained.According to the fact that the accuracy of internal spline still cannot meet the requirements after cold extrusion,a precise shaping method was proposed to improve the accuracy of internal spline;the influence rule of each process parameter on the accuracy of internal spline in the cold shaping process plan was obtained through numerical simulation analysis;the orthogonal experiment and finite element method were used to optimize each process parameter and its interactive combination in the cold shaping process plan,and the best process parameter combination was obtained.Based on the results of numerical simulation and the optimized process parameters,the molds were designed and processed and the process test was carried out.The results of the process test shown that the cold shaping method could be used to manufacture gears with satisfactory accuracy.The test results verified the correctness of the numerical simulation.