① Aiming at the problems of serious tooth tip collapse, low material utilization, low forming accuracy and low die service life after cold extrusion forming of large module spur gear, a new through continuous “cold extrusion + cold shaping” composite forming process method is proposed, and the composite forming die is designed. The numerical simulation and process experiment show that, The tooth top of spur cylindrical gear produced by composite forming process is fully filled, the accuracy of spur cylindrical gear reaches grade 8, and the service life of die can reach 150000 pieces.
② A multi-objective optimization method for cold extrusion process parameters of spur gears is proposed. Taking response surface method as the optimization method, the optimal combination of cold extrusion process parameters is obtained by optimization. The influence law of cold shaping mode and shaping quantity on the accuracy of spur gear is put forward, and the reasonable cold shaping mode and shaping quantity are determined.
③ An optimal design method of cold extrusion combined die for spur gear is proposed. The Kriging model combined with particle swarm optimization algorithm is used to optimize the equivalent inner diameter, diameter ratio and interference coefficient of the spur cylindrical gear tooth cavity of the combined die, obtain the best structural size of the combined die, and effectively reduce the overall size of the combined die on the premise of ensuring that the service life of the die will not be reduced.