Optimization Of Forming Process Of Automobile Output Shaft And Control Of Rolling Defect

Cross wedge rolling is an advanced near-net forming technology with high production efficiency,high material rate and high precision of rolling stock.In the actual production of cross wedge rolling technology,multi-step shaft forming often has defects such as internal hollow looseness and external step spiral bevel.As a result,the size and quality of the parts are not satisfactory,and the fatigue life of the rolled products are greatly reduced.Due to the complicated three-dimensional elastoplastic forming process of cross-rolling multi-step shafts,most of the relevant references at home and abroad are aimed at studying the small and simple wedge-shaped rolling shaft forming defects.There are few research references on the defects such as shaft end looseness and step spiral bevel appearing during the rolling forming of complex multi-step shafts.Taking the multi-step complex shaft automobile output shaft in actual production as the research object,the rolling process plan of the shaft is analyzed.Combining with the references and actual rolling experience,the shaft blank size(diameter and length),mill model,and material head position are determined.The hot blank size,mold groove shape,mold wedge shape,mold fracture position and wedge baffle design method are given.The Deform 6.0 finite element simulation software is used to establish the rolling output rolling model of the automobile output shaft.Deform 6.0 finite element simulation software is used to analyze the deformation law of the multi-step shaft of the automobile output shaft and the formation law of the internal defects of the rolling stock.Considering the interaction of process parameters,orthogonal experiments are carried out with three factors of forming angle?,broadening angle?and rolling temperature T.Combining with the actual rolling experiments,the optimal combination of three major process parameters,the forming angle?=22°,the widening angle?=8.41°and the rolling temperature T=1100°C,are obtained.The spiral bevel defects of the rolling stock are analyzed,and the influence law of the rolling curve on the right angle steps of different positions of the rolling stock is studied.According to the principle of volume balance,the equilibrium relationship between the wedge volume V_d of the mold and the corresponding step volume V of the rolling stock is established under the action of the rolling curve.Finally,according to the change rule of the axial end of the workpiece step,the rolling curve equation of linear function is established by using various parameters and conditions,and the rolling curve is verified by the combination of finite element simulation and rolling experiment.The number of repairing steps reduces and the accuracy of the rolling data improves.The research results show that the forming angle?and the rolling temperature T are the key factors for the internal hollow porosity of the rolled piece;the mold rolling curve is the key factor affecting the external spiral bevel of the rolled piece.Using the combination of finite element simulation and rolling experiment,it provides an effective solution to the above defects,and gives a new rolling curve equation based on complex multi-step axis.The research results provide a theoretical basis for the actual production of multi-step shafts.