The Upsetting Process Analysis And Experimental Research Of The Preform Of U-Joints Of Steel Tie Rod

Steel tie rods are stress-bearing structural parts made of high-quality alloy structural steel rods or stainless steel rods with the advantages of high plasticity and high strength.They are widely used in infrastructure and large-scale construction projects such as railways,buildings,docks,stadiums,etc.With the rapid economic development,the requirements for the quantity,quality and performance of steel tie rods are getting higher and higher.At the present stage,steel tie rod joints and rod bodies are mostly processed separately,and then the two parts are connected to produce steel tie rods.This process has low production efficiency,high processing cost,and mismatched overall performance,so new processes are studied to produce steel tie rods with engineering practical value.In this paper,through the analysis of the structure and characteristics of the steel tie rods,it is proposed to use an integrated forming process to produce steel tie rods.In the integrated steel tie rod forming process,the U-joint is formed by the reverse extrusion process,and the blank prepared for the reverse extrusion is called the preform.When preparing the preform,the height-diameter ratio of the blank used exceeds the range of the normal upsetting ratio,making the forming of the preform into a large height-diameter ratio upsetting forming,which is the focus of this paper and is also a difficult forming problem.The engineering calculation method is used to establish the mechanical model of the blank upsetting forming,and the forming force required for each pass in the upsetting process is calculated.The DEFORM-3D numerical simulation software is used to model and simulate each process of the preform of U-joint of 35-type steel tie rod,and the temperature field,stress field,strain field,metal flow law,punch load,etc.during the deformation process are analyzed.The simulation process verifies the feasibility of preform forming,and obtains the optimum hot forming process parameters for each pass:the initial forging temperature of the first pass is 1150?,while the punch speed is 20mm/s;the initial forging temperature of the second pass is 1150?,while the punch speed is 30 mm/s;the initial forging temperature of the third pass is 1100?,while the punch speed is 20 mm/s.On the basis of theoretical analysis and simulation,corresponding molds were designed and experiments were conducted to verify the feasibility of the forming process and the rationality of mold design.Through the research of this subject,the upsetting forming of the preform of U-joint of35-type steel tie rod is realized,which provides a basis for the design of the die and is a key step in the research of the integrated process of the steel tie rod.