Research On One-Step Cold Extrusion Forming Method Of Truck Planetary Gear

Planetary gears are one of the important components of heavy-duty vehicles,and their performance determines whether the performance of the vehicle is excellent.Currently,planetary gears are mainly processed by gear hobbing,gear shaping,gear shaving,and other cutting methods.However,traditional cutting methods have problems such as low material utilization,rapid tool wear,and high costs,which seriously affect the mass production of planetary gears in the gear manufacturing industry.Cold extrusion technology is a precise plastic forming method.The surface quality and mechanical properties of extruded parts formed by cold extrusion technology are good,and have gradually been applied to the manufacturing of planetary gears.Currently,the commonly used cold extrusion processes include: hot forging hollow blank-annealing-machining-surface treatment-cold extrusion forming outer teeth-machining.However,due to the need to retain large machining allowance in processes such as hot forging blank,problems such as long process routes,high energy consumption,high material consumption,and high cost have occurred,seriously affecting the promotion and application of cold extrusion technology in planetary gear production.Therefore,how to improve the forming quality of automotive planetary gears,reduce processing procedures,reduce energy and materials consumption,reduce production costs,and improve product market competitiveness has become the top priority in the gear manufacturing industry.This paper takes planetary gears as the research object,analyzes the traditional through-type cold extrusion process based on the structural characteristics of planetary gears,and proposes a one-step cold extrusion forming process plan for planetary gears;Using UG to establish a three-dimensional model,and using DEFORM finite element software,the effects of parameters such as the half angle of the die entrance,the length of the die sizing belt,the taper of the upper punch,the cone apex angle of the lower punch,and the height difference between the die and the lower punch on the forming quality and load were studied respectively;Orthogonal experiments were used to optimize the parameters,and the optimal combination of parameters was determined with the objective of reducing the forming load;By establishing an elastic-plastic finite element model,the formation mechanism and distribution law of gear tooth errors were studied.The tooth profile accuracy was improved by modifying the pressure angle;Finally,based on the numerical simulation results,a cold extrusion mold was designed and manufactured,and process tests were conducted.The test results showed that the forming quality and precision of the extruded parts formed using this process scheme met the product design requirements.The test results were basically the same as the simulation results,verifying the feasibility of the one-time cold extrusion forming method.