Research On Deformation And Microstructure Of Cold Orbital Forging Of A Spur Bevel Gear

The spur bevel gear is an important part in the transmission system and it is widely used in automotive, marine, aeronautical, astronautical, mechanical and chemical industries. As the increasing development of industrial areas, the spur bevel gear with high performance is still required to improve and this can not be achieved by traditional forming method. Cold orbital forging is an advanced precision forming technology which is widely applied to manufacture spur bevel gears. This technology can not only significantly save the energy and material, reduce the cost and enhance the efficiency of productivity, but also improve the microstructure and mechanical performance, which can extend the life of the spur bevel gears greatly. However, cold orbital forging of a spur bevel gear is also a complicated process with interactive factors, leading to its evolution laws of the macroscopic deformation and microstructure quite complex. Therefore, this paper systematically investigates the macroscopic deformation and microstructure evolution laws of the cold orbital forged gear by finite element(FE) method and experimental analysis.Based on the DEFORM-3D platform, the sound 3D rigid-plastic finite element(FE) models of cold orbital forging of a spur bevel gear with two steps(the preforming step and the final step) are developed. Through these FE models, the distribution and evolution of effective strain, metal flowing velocity and damage factor, and the evolution of axial forging load are detailedly studied. Moreover, this paper investigates the influence laws of the four key factors(rotation velocity of the upper tool n, feeding velocity of the lower tool v, tilted angle of the upper tool γ, friction factor between the tools and the billet m) on the geometry, the deformation inhomogeneity, damage and the maximum axial forging force in cold orbital forging of the spur bevel gear. And the four key factors are optimized reasonably. According to the analysis above, the corresponding experiments of cold orbital forging of the spur bevel gear are conducted and there is a good agreement between the experimental results and the simulation ones, which validates the reliability of the optimized data.By using the spur bevel gear obtained in the experiment, this paper comprehensively investigates the distribution laws of the grain, Vickers hardness, carbide and texture in the cold orbital forged gear. On the basis of the investigation above, this paper reveals the correlative mechanism between the macroscopic deformation and microstructure in cold orbital forging of the spur bevel gear.Through the heat treatment experiment, this paper reveals the distribution laws of the grain, Vickers hardness and carbide in the cold orbital forged gear.The results can provide valuable guidelines for cooperative control between the geometric accuracy and performance in cold orbital forging of spur bevel gears.