Automobile Axle Rod Closed Radial Warm Extrusion Forming Research

With the development of the society since the reform and development in China,our country has become the largest country in the car ownership in the world.Axle rod as an important part in automotive steering assembly,its performance directly affects the safety of the car and also attracted the attention of the manufactures.Rod making in traditional produce is low utilization rate of materials,product quality is relatively poor,and the problem such as die life is short,poor labor conditions,can not meet the development of the industry "near net shape" and "green manufacturing" requirements.Under this background,this paper proposes a car pull rod closed radial warm extrusion forming process,and researches many problem such as the temperature changes in the rod forming process,metal flow characteristics,forming force calculation and forming equipment selection,blank size optimization and lubrication,die structure design and key technical problems,all this deepening the understanding of the forming process.In this paper,with the help of fem simulation software DEFORM-3D,thermal coupling problem of rod forming simulation,completed in three phases.Simulation results show that the temperature on the pull rod forming has a direct effect of key parts,such as ball temperature lowering speed too fast,the scarf will appear crowded compression end due to insufficient metal flow.With 40 Cr for billet rod forming simulation,the temperature control in 740~760? is advisable.Studied the rod metal flow,from the finite element software can clearly see the metal flow of each point.Before metal not into radial branches,mainly in the mold cavity happens the upsetting deformation.When a radial extrusion,the metal flow direction suddenly change,a certain angle to the vertical axis into the concave cavity,plus metal with the die cavity of the friction effect,the flow of metal is in turbulent flow,if not to lubricant improving extrusion conditions,it is easy to fold and insufficient angle gap filling.By comparison,this paper select boron oxide + graphite 25% as extrusion test of lubricant.Rod forming neither belongs to plane problem not to axisymmetric problem,it is difficult to calculate the forming force.In this paper,according to the extrusion stage are calculated respectively upsetting stage and filling stage of radial extrusion,and clamping force,obtaining the calculating formula of total extrusion rod.According to extrusion size optimization extrusion equipment,and finally confirmed for 3000 kN double-action hydraulic press machine.In this paper,we choose the commonly used tungsten molybdenum steel as the mould material,and taking the extrusion die structure design.According to the forming characteristics and experience formula to optimize cavity size.Finally,in press machine carry on the pull rod extrusion experiment,the problems of the finished parts is analyzed,and improvement measures are put forward.Test results and the theoretical analysis and simulation results have good consistency,demonstrate the feasibility of tie rod radial temperature extrusion forming,providing experiences for the application of this process.