Design And Numerical Simulation Research On Plastic Forming Process Of Automobile Rear Axle Half Shaft

With the rapid development of automoblie industry,auto products made in China are gradually occupying the international market.The requirements for the design and manufacturing of automoblies and auto parts are improved based on the high quality,high efficiency,low energy consumption and low costs.The rear axle half shaft as an important part in the automoblie transmission system has also been put forward to higher standards.Through transmitting the torque,the rear axle half shaft can make the left and right drive wheels have differential function during driving.In the harsh servo environment,the manufacturing accuracy and mechanical strength of the rear axle half shaft directly affects the performance and service life of the vehicle drive rear axle system.The rear axle half shaft is a large plate and long axis part with the long length and large axial cross-sectional area variation,which is composed of flange plate,stepped shaft and spline.The flange plate has a complex structure,a small height-to-diameter ratio and high dimensional accuracy,and the diameter change of the stepped shaft is small and the length is long.The traditional production processes of half shafts include machining,multi-process forging,rolling and composite processes.In the production process,there are some limitations such as poor forming quality,low forming efficiency,and low material utilization rate,which do not meet the needs of light-weight,green and intelligent automoblie developments.In order to reduce the research and development cycle and production cost of the half shaft,the research and numerical simulation of the composite plastic forming process of half shaft are carried out in this work,as well as improving its production efficiency,forming quality and product precision.The main research contents are as follows:Based on the part drawing,the structural characteristics of the automoblie rear axle half shaft parts are analyzed,and the half shaft plastic forming process plan and process flow are designed.Roll forging process is used to form the half-shaft stepped shaft part,and the swing rolling and precision upsetting process are used to form the flange.The relevant process parameters of the above scheme are analyzed and calculated.Subsequently,the roll forging parts drawing and the roll forging pass are determined,the ellipse-circle groove system is selected,the groove size parameters are calculated,and the two-pass roll forging die is designed.The size and forming force of the swing rolling forming and upsetting forming of the flange plate are calculated.And the selection of devices is completed.DEFORM-3D software is used to analyze the two-pass roll forging forming process of the stepped shaft of the rod,and revise the structure of the mold.The effects of initial temperature of blank,initial temperature of mold,friction and forging roll gap on formability,strain field.Temperature field and mold load are studied,and the parameters are optimized on these bases.Based on the optimized parameters,the distribution of stress-strain field,metal flow velocity,mold load and temperature filed during the forming process are analyzed.The results indicate that the part with good metal flow linearity and high forming quality can be produced through roll forging process,and the forming time is about 3 seconds.In this process,the utilization rate of materials is high,the production coat is low,a small amount of machining is required in the follow-up,and the production efficiency is also greatly improved.The swing forging forming process of the flange is studied,and the evolution mechanism of stress-strain field,forming load,temperature field and damage are analyzed.The swing forged flange has low dimensional accuracy,which requires much follow-up machining and about 10 seconds to form.In this process,the load stability is stable,the overall stress-strain distribution is more uniform.Nevertheless,there is a high stress concentration in the crack prone area.In order to solve the problem of insufficient filling in some areas,the one-fire one-step precision upsetting forming process of the flange plate is designed,and the mold fillet is optimized.Through numerical simulation,the effect of temperature,friction and operating speed on load and stress is discussed,the optimal combination of process parameters is determined.On the basis of the above research,the feasibility of one-step upsetting of flange plate is verified through analyzing the stress-strain field,velocity field,load and temperature field in the forming process.The results indicate that one-step upsetting can produce the flange plate part with high dimensional accuracy.The utilization rate of materials is high,and the forming time is about 2 seconds.The forming load is large but still within the rated range.In addition,the distribution of stress-strain is reasonable,which can fully meet the performance requirements of half shaft products.