Compound forming technology of continuous cold extrusion and cold shaping of spur gear for truck

From the multi-objective optimization of cold extrusion process parameters of spur gear, the influence of shaping quantity on the accuracy of large module spur gear, the selection of cold shaping mode of large module cold extrusion spur gear The key technology of continuous “cold extrusion + cold shaping” compound forming of spur gear is systematically and comprehensively studied from the aspects of optimal design of cold extrusion combined die for spur gear. The main research contents are as follows:

① The compound forming process scheme of through continuous “cold extrusion + cold shaping” of spur cylindrical gear for truck is put forward

Aiming at the problems that the precision of straight cylindrical gear for truck can not meet the requirements of Grade 8 and the subsequent machining allowance is large, a new compound forming process scheme of straight cylindrical gear through continuous “cold extrusion + cold shaping” is proposed.

② Optimization of cold extrusion process parameters for spur gears

Aiming at the problems of large machining allowance of end face, large collapse angle of tooth top and large forming load after cold extrusion forming of spur gear, taking tooth top fillet, die angle, splitting thickness and sizing belt length as optimization variables, multi-objective optimization of process parameters of cold extrusion forming of spur gear is carried out by using response surface method and finite element numerical simulation, so as to reduce machining allowance of end face of spur gear Aiming at improving the filling ability of the tooth top and reducing the forming load, the second-order response surface models of three objective functions are established respectively. Through optimization in the feasible variable space, the optimal process parameter combination of cold extrusion forming of large modulus spur gear is obtained, and the optimized optimal process parameters are verified in practice.

③ Selection of cold shaping mode and optimization of shaping quantity of spur gear

Based on the measured shape and size of cold extrusion gear, the elastic-plastic finite element simulation model of spur gear cold shaping based on error model is established. Through numerical simulation, the stress-strain distribution of spur gear and the stress of tooth concave die under different cold shaping methods and quantities are obtained The influence of shaping quantity and sizing belt length of shaping die on the total deviation of spur gear profile and helix. According to the simulation results, the cold shaping process experiment is carried out to determine the reasonable cold shaping mode and amount, so as to prepare for the subsequent compound forming process experiment.

④ Optimum design of cold extrusion combined die for spur gear

Taking the equivalent inner diameter, diameter ratio and interference coefficient of the tooth cavity of the cold extrusion combined die for spur gear as the design variables and reducing the equivalent stress on the inner wall of the die core as the optimization objective, the Kriging model between the structural parameters of the combined die and the maximum equivalent stress of the die core is established, and the particle swarm optimization algorithm is applied to optimize in the feasible variable space to obtain the optimal structural size of the combined die.

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