Research On Simulation Of Warm Precision Forging Processes Of Spur Gears And Stress Calculation Of Concave Die

Comparing with the traditional metal cutting method, the precision forging of gears has many advantages such as efficient use of material, high productivity and good mechanical property of work pieces. Therefore, the precision forging of gears has become the researching focus at home and abroad. With the help of finite element simulation software, DEFORM-3D FEM, and combined with the traditional force analyzing method, this thesis focuses on a study about the force analysis and the stress calculation of the warm precision forging process.Based on the discussion about the characteristics of the warm forging and cold finishing of gear precision forging process and die structure, this thesis builds modals of the main die parts in the warm precision forging process of gears by using3D modeling software Pro/E4.0on spur gear parametric modeling. With the help of DEFORM-3D, this thesis also builds the three-dimensional finite element model of blank diameter positioning and floating die structure in warm precision forging of gears and numerically simulates the forming process of gears and die cavity corner filling condition. In addition, the rules of billet stress and strain distribution in different moments and changes of temperature field are analyzed.Warm precision forging processes of two groups of spur gears are simulated and analyzed by using DEFORM-3D finite element simulation software. The teeth of gears in group I are36and numbers of models are respectively2,4, and5. The teeth of gears in group II are respectively18,36and72and the number of models is2. Then maximum forming force is calculated using the obtained punch load curve. Based on the hypothesis that the maximum forming stress of unit blank is the working load of dies, the ratio of the flowing stress of blank and working load of dies is calculated. The results show that:for the gears in group I, the ratio is respectively5.3,5.7,6.0; for the gears in group II, ratio is respectively5.0,5.3,4.7; the results also show that in the warm precision forging process of gears with modules2-5, the working load of die is5-6times of the flowing stress of blank.Furthermore, die stress of the two groups of gears in the warm precision forging process is analyzed based on finite element simulation method. The maximal equivalent stress the concave die in the forming process of is obtained. At the same time, tooth root circle diameter of concave cavity model, pitch diameter, diameter of addendum circle as the die diameter are selected and the maximum equivalent stress of the two groups of spur gears is calculated by using thick wall cylinder formula. The analysis and comparison of the maximum equivalent stress and the maximum equivalent stress ratio show that:the ratio is only in1.0～1.1and it will be the largest when the addendum circle is taken as the inner diameter in the die stress calculation. It is found that:with addendum circle as the inner diameter, it is convenient to calculate maximum equivalent stress of the concave die by using the thick wall cylinder formula and it is more reliable when it is magnified to1.1times. All these are of great value in analyzing the stress of forming die in precision forging of gears.