Research On Secondary Cold Extrusion Forming Method Of Large Modulus Spur Gears

Spur gears are one of the most common transmission parts in the machinery and automotive industries.Due to their high transmission efficiency,good meshing performance,strong bearing capacity and compact structure,they play a very important role in industrial production.At present,the processing and manufacturing of spur gears are mainly completed by mechanical processing,such as gear hobbing,gear shaping,gear grinding,etc.However,due to the shortcomings of low material utilization rate,low production efficiency,and rapid tool wear,it is difficult to meet the needs of mass production.Cold extrusion technology is a plastic forming processing method with high production efficiency,low manufacturing cost and suitable for mass production.By forming gears by cold extrusion technology,the surface quality and mechanical properties of products can be improved.With the development,more and more gears are processed by this forming method.However,due to the complexity and uncertainty of the metal flow in the gear extrusion process,the tooth direction accuracy of the cold extrusion gear cannot meet the product requirements.Therefore,the key problem to be solved in the process of formulating the cold extrusion process is how to effectively improve the tooth direction accuracy and reduce the processing cost.This subject takes the planetary gear of the wheel side reducer for trucks as the research object.Aiming at the characteristics of large module,large tooth height and high tooth precision,the secondary cold extrusion of large module spur gear is proposed.Press forming process method,and compare it with the traditional cold extrusion forming process in terms of forming quality and precision through numerical simulation;at the same time,numerical simulation of the cold extrusion process is carried out by using finite element simulation software,and different blank tooth profiles are analyzed.The influence of parameters such as clearance,punch working belt length,punch cone apex angle,friction coefficient,and lower ejector extension length on tooth direction accuracy,forming load and forming quality;orthogonal experiments are used to conduct multi-parameter analysis of main process parameters.The optimal process parameter combination is determined by the interactive combination optimization.Based on the elastic-plastic theory,the influence law of the elastic deformation on the tooth direction accuracy after the extrusion part is released from the mold constraint is analyzed.The inverse compensation method is used to repair the tooth direction of the mold.shape and improve the tooth direction accuracy of the gear.Finally,according to the parameter optimization results,the cold extrusion die is designed and manufactured,and the secondary cold extrusion forming process test of the spur gear with large modulus is carried out.The process test results show that the forming accuracy and forming quality of the secondary extrusion part of the spur gear with large modulus can meet the product requirements after the secondary cold extrusion forming is carried out with the optimal combination of process parameters.