Process Analysis And Experiment Study On Cold Precision Forging Of Straight Inner Gear

With the rapid development of automobile, motorcycle, agricultural vehicle and ship, the demand of gear quality is increasingly high. Straight inner gear is one of the key parts of reducer, which can replace the large and heavy structure in reducer, and make the existing transmission structure compact and flexible. There are a great deal of advantages by using cold precision forging process, such as higher production efficiency, saving materials, lower costs, higher intensity, greater precision and surface quality, etc. Thus, cold precision forging will have a bright future in industrial application.Before the simulation analysis of cold precision forging process of inner gear, the 3-D geometric shape of inner gear is modeled based on the parametric design idea of Pro/Engineer. Each size of the model is treated by parameterized and certain constrained relationship among sizes is established. Therefore, the complex process of geometric modeling is converted into a parameter table which is composed of some key parameters of inner gear. By using such table, a required shape of inner gear can be obtained just input the relevant parameters of gear.The cold precision forging process of two kinds of inner gear with typical structure (hole-through inner gear & non-hole-through inner gear) is proposed. By numerical simulation, some key parameters such as gear module, forming load, effective tooth height and die life are researched on hole-through inner gear's forming quality. Meanwhile, in comparison with the two feasible schemes on non-hole-through inner gear in terms of forming load, gear accuracy and die life, applicable conditions of the two schemes are obtained respectively.Through analyzing the state of die force when solid billet is used to form non-hole-through inner gear, the structure of three-layer combined die is put forward. With the help of artificial neural network and genetic algorithm, the design-parameter of the combined die structure is optimized, which can fully exert material properties of the combined die.Finally, experimental verification is carried out for cold precision forging of hole-through inner gear and great gear part is gained. The fact that the experimental and numerical simulation results showed well coincidence, further proved that the cold precision forging process scheme for hole-through inner gear presented in this paper is reasonable and feasible.