Die Deflection In Cold Net-shape Forging Of Spur Gear And Die Compensation

Die elastic deformation and component spring-back is unavoidable in cold net-shape forging technology of spur gear, and they play an important role in dimensional accuracy. In this paper, die deflection and component spring-back is regarded as the research object. Component dimensional error is pre-estimated exactly, then die compensation is carried out according to error distribution in gear tooth surface, and accuracy of gear forging is increased at last.Adopting numerical simulation, elastic-plastic deformation of gear forging and die elastic deformation is calculated at the meantime. Firstly, processing parameters, such as ratio of external diameter and internal diameter height of female die coefficient of friction are studied, and their influence on die deflection and component elastic recovery is analysed. Secondly, castellated assembling die is designed by iteration optimum method. Thirdly, optimum die is employed, and the rule of die elastic deformation and component elastic recovery is researched. Last, according to error analysis results, negative expensation compensation factor is brought forward, and female die is compensated by golden section method, to gain involute gear product, whose accuracy is satisfied.In cold forging of spur gear, die surface is expanded radially. Numerical value of die deflection is distributted variably in profile of tooth height of tooth normal direction of curve. Gear unloaded, component elastic recovery is generated in radial direction, and its value affects component accuracy. Die deflction and component spring-back makes normal deviant of various points in involute vary. The method brought forward in this paper can compensate the die of cold forging accurately and obtain gear product, which is provided with high degree of accuracy.