Study On Precision Forging Process And Die Wear Of Brass Synchronizer Ring

Manganese brass (HMn34-2-2-1) is widely used to vehicle synchronizer ring sinceit has perfect wear resisting property and high strength. However, its forgingtemperature is quite narrow which would restrain it applications. Moreover, because thering wall of synchronizer ring is very thin and its tooth fillet is small, the stressconcentration and material damage would appear on the forgings. The low materialutilization ratio is also a key problem for the forging process. Based on such problems,the forging process and die service life were studied by using the method of physicalexperiment, finite element simulation and the essential theory of hot forging process anddie wear. The main study works are as following:①Study on the hot deformation behavior of Manganese brass (HMn34-2-2-1). Inorder to acquire the true stress–strain curves of Manganese brass, hot compressionexperiment was conducted using the hot forging reappear experimental facility“THERMECMASTOR-Z” hot simulation test machine. The constitutive model of theHMn34-2-2-1was established by analyzing its hot deformation behavior which laid thetheoretical foundation for the forming performance and finite element simulation of thesynchronizer.②Hot precision forging die design for the synchronizer ring. Considering theeffects of linear expansion and elastic deformation caused by the temperature, theforging die of the synchronizer ring was designed, which can guarantee the precision ofthe forgings.③Optimization of forging process of the synchronizer based on Tauguchi method.In order to improve the material utilization ratio, the billet dimension was optimizedusing the criterion of fillet thickness. The multi-objective optimization which seteffective stress, material damage and forging load as the goal was constructed based onTauguchi theory. According to the defects from the simulation, such as stressconcentration and material damage, the effects of forging velocity, billet initiatetemperature and friction factors to the defects were investigated, respectively. In orderto decrease the defects, the optimal forming parameters were acquired using theoptimization model which were billet initiate temperature650℃, forging velocity200mm/s and friction factor0.45.④The prediction of die wear and die service life based on BP BP neural network. The classical Archard model was revised combined with the finite element simulation.The network model of mold cavity and wear was constructed by BP neural networkwhich can predict the wear of any point of the cavity efficiency. The effects oftemperature, normal pressure and slip velocity after forming to the ones of next formingcircle was considered, and the relationship of wear value and forging times wasobtained by mathematical fitting method which can predict the die service lifeefficiently.The research work can provide reference for the study on the forging process anddie wear of the similar parts which has practical engineering significance.