Simulation And Experimental Research On The Floating Die Cold Forming Of Helical Gears

Because of the advantages such as good meshing characteristics, high load capacity, low noise and so on. Helical gears have been widely applied to the mechanical industry. At present, the main forming methods are still machining. Although the process has been gradually improved, but it also exists some inevitable shortcomings, such as metal streamline is destroyed, strength of teeth are decreased and also the material utilization is lower. In order to meet the requirements of green manufacturing, it is necessary to use the method of plastic forming for helical gears.In this paper, two processes are put forward, one is floating die forming, another is rolling forming. And numerical simulation and physical experiments are used to study the process.According to the process of floating die, the finite elements software DEFORM-3D is used to study the forming process, and also physical experiments are done with lead. In the research, the laws of the metal flowing,forming load, equivalent strain and stress, factors that affect the precision of forgings after demolding are analyzed. The forging process with floating die is compared with the conventional scheme. The results show that the cold forming load of floating die can be reduced effectively, and when demoulding, the helical gears make rigid rotation along the helical directions. This can effectively avoid the destructive forming that caused by the cavity. The main factors that affect the precision after demoulding are frictional factor and helix angels. On the basis of floating die, measures of divided flowing process and decompression which have been used on the forging of super gears are used to form the helical gears. During the forming process, velocity field and metal filling degree are emphatically studied. This provides a reference for the further research of helical gears.With the way of conventional extrusion, helical gears may get stuck in gear die because of its helical angles. This can cause some difficulties during the demolding process. Based on the meshing theory of gears, the latter part of this paper has studied rolling forming for helical gears. Through the theoretic computation, profile dimension of rolling mould, geometric relationships between blank diameter and addendum circle of rollers are designed accurately. The rolling processes include three stages, tooth dividing, forming and sizing. By numerical simulation, forming faults of the three stages are predicted, and put forward solutions. This study provides reference for later research.