Study On Warm Precision Forging Of Half Axle Gears

Enclosed-die forging process is one of the advanced processes in the field of metal forming. Full tooth of gear can be obtained through precision forging process, and the tooth need no or little precision machining only. The structure and performance of gear can be improved effectively through this process. The process can make material depressed stress in three directions. So it can attenuate crystal grains, improve the density and decrease microcosmic defects. It can also make metallic fibre streamline of teeth more continuous and symmetrical, and lead to the improvement of mechanical performance of gear. The precision of gear shape can come to a very high level。The workpiece needs only a little of machining before heat treatment. The process increases productivity rate and use ratio of materials, decreases the cost of production. Therefore the competing ability of gears is improved greatly.During recent years, with the rapid development of computer technology, the technology of enclosed-die forging has achieved great progresses. In this research a kind of half axle gear was introduced, whose model was made by the CAD technology. The forming process of the half axle gear was simulated by FEM software. The transformations of the fields during the process of metal forming were investigated, the tendency of metallic flow was forecasted,and the rules how various items affect the forming load, metallic flow, the life of dies were discovered. The factors include the different structures of male and female die, web thickness, the distance between web and big-end face of gear, etc. And the most suitable die structure,web thickness and distance were made certain. A proper warm forging process and a die-set based on 800-ton double action hydraulic press were designed according to the result of FEM simulation. Finally some experiments were made. Contrasting the simulation result with the experiment result some conclusions were made: modifying die structure (setting a tip at the big-end of gear to hold unwanted material) can ensure the complete forming of the tooth; modifying male die structure (adding a dummy on the bottom of male die to produce a radial force helping to divide material flow) can improve the filling ability in the area of teeth; proper web thickness and wed position play an important role in the forming of gear (the proper values are t=0.3d and h=0.5H); If a hole with diameter less than 25mm on the gear should be forged by proper die structure, it even helps to metallic flow in the area of teeth.The theory of precision forging, technology of FEM simulation and mould CAD/CAM are integrated through this research, which helps to shorten developing period, prolong life-span of die, and cut down the cost, etc. The progeny of the research can provide accordance for other bevel gears' producing.