Research On The Cold Precision Forging Of Helical Gear: Forging Process And The Numerical Simulation Of The Forming Process

A gear is a kind of important driving part used in car. In recent years, with the rapid development of automobile, there is a much stricter demand to gear's manufacturing. At the present time, gears are mainly manufactured by metal cutting or by a combination of conventional hot forging with machining, which results in high production cost and much manufacturing time. Cold precision forging of gears has a lot of advantages when compared to conventional gear shaping, such as material saving, better mechanical properties and higher productivity, cold precision forging has become the trend of manufacturing gears especially the gears used in car. Based on the rapid development of cold precision forging of gears and the project requirement of the 11th five-year National Key Technologies R&D Program that is taken by our research team, this paper aims at a detail investigation of cold precision forging of helical gears.The study in this paper was performed by the combination of numerical simulations and experiments. The parameterization CAGD of helical gear and dies using PROE were realized. The rigid-plastic FEM was introduced and several important problems such as remeshing, volume change and convergence were discussed.The analysis of the kinetic forming die and divided flow in the process of gear cold forming has been carried out, based on it, a new technology for helical gear cold precision forming-two direction controllable upsetting-extrusion is presented in this paper, which made full use of the principle of kinetic forming die and divided flow, and combined the two effectively. So, the new technology played a positive role in reducing forming load and improving the tooth filling.A plenty of numerical simulations have been carried out to analyze the various processes of gear precious forging, a comparative analysis of tooth filling and load has been carried out, at the same time, the stress and strain distribution and the distribution of metal flow rate in the process of deformation have been get. As a result, the regularity of metal flow in the process of gear forging has been study qualitatively.At last, the forming experiments of the process of two direction controllable upsetting-extrusion have been made; the experimental results are in good agreement with the numerical simulation results. It also has been proved that the process of two direction controllable upsetting-extrusion is feasible.