Microstructure & Flow States Simulation Of Gear Shaft Hot Forging Process And Die-wear Analysis

Gear-shaft is a significant component with high transmission efficiency, compactness and long life. Currently the machining prcuding method has been gradually replaced by the advanced gear-shaft precise forging process which achieved good results. To effectively satisfy the work requirement of the gear shaft, mechanical properties and dimension precision of forgings should be improved.With the ensurance of the gear shaft forging formability, the fine and homogeneous microstructure would improve the mechanical properties, while improving the die-wear resistance property would incraese the dimension precision. According to the FEM simulation of the gear shaft forming process, the material flowing, temperature, stress and strain field were calculated. Combined with various models, the distributions of microstructure evolution and die-wear were obtained.The single-step and multi-step hot forging processes of gear shaft were simulated using the Deform-3D FEM software. According to recrystallization formulas of Yada model, the influences of initial billet temperature, friction condition and punch speed on the microstructure distribution were analyzed, and the microstructure evolutions of four forming processes were compared. With the Flownet module of Deform-3D, the shapes of forging flowline were simulated. To improve the material flow uniformity, local cooling method was proposed, and the material flow conditions were simulated. Based on the development, the advanced Archard model was introduced in Deform-3D to calculate the influence on the die-wear of the different process parameters, and the die-wear distribution of floating die was calculated. To sum up, the multi-forming process was effective in improving the microstructure distribution, flowline shapes and die-wear decrease.Hot forging experiments of gear shaft were carried out, metallographical photos and flowline specimens were presented to verify the reliability of simulation results. Based on the numerical simulation and experimental results, the guidances of practical production processes were proposed.