Study On Warm Precision Forging Of Spur Gears With Big Modulus And High Boss

With the development of the automobile industry, high requirements on plastic forming of spur gears are put forward. Fully closed precise plastic forming processes are suitable to the forging which have complex shape, high dimension accuracy, good surface quality and using properties. At present, this process has been taken more and more attention from all over the world.This paper deals with warm precision forging of accurate spur gears with big modulus and high boss. The spur gears with big modulus and high boss are critical parts in the automobile industry. Constrained divided flow method is applied successfully to these gears. Trapeziform groove, as constrained divided flow device, is used to fill up both the spur gear and the high boss. The gears can be produced in one step process operation.By the adoption of active die-Trapeziform groove constrained divided flow method, the die is specially designed and manufactured for warm precision forging of spur gears with big modulus and high boss. The technological experiment on the precision forging of spur gears with big modulus and high boss has been done. The forming of the spur gears is simulated by three dimensional rigid plastic finite element method, the material of the billet is Pb. By finite element analysis and experimental study, metal flow behaviors and deformation mechanics of spur gears with big modulus and high boss which treated by precision forging are obtained. The numerical simulation results are in good agreement with the experimental results. The result of the numerical simulation and the experiments showed that the divided flow, especially the active die-Trapeziform groove constrained divided flow applied in the final forging stage, was very effective on improving the gears teeth filling and decreasing the forging load .From the results of numerical simulation and experiment, the bottom boss of the gears has difficult to fill up fully. In order to solve the defect, the die and billet are improved on. The technological scheme is proved to be reasonable by numerical simulation. With the better technological scheme, the precision forging of the spur gears is simulated by three dimensional rigid viscoplastic finite element method, the material of the billet is steel(35#)and the temperature of forming'is 400℃. The numerical simulation results of temperature, effective stress and effective strain are obtained .