Mechanical Analysis And Forming Process Parameters Of U-Joints Backward Extrusion Of Steel Tie Rod

As one of the products of steel structure,steel tie rod has the advantages of high strength,shock resistance and good impact resistance.With the increasing of large hoisting projects in our country,the demand for high strength steel tie rod is increasing,the demand for high-strength steel tie rod is increasingly large.At present,most of the domestic steel tie rod products adopt the traditional thread connection or welding method.The product structure is single,and the performance is largely limited by the structure,which does not meet the high performance requirements.In order to upgrade the technology of steel tie rod products and enhance the competitiveness of China's steel tie rod industry in the world,the material and forming process of steel tie rod and its components have become the key research and development content of the industry.According to the structural characteristics of the steel tie rod,the integral steel tie rod is putted forward,that is,forming the steel tie rod by means of integral forging.In the whole forming process of steel tie rod,the last forming process is to form U joint by backward extrusion,which is the key and difficulty of the whole process.By establishing slip line field in back extrusion process of U joint,the extrusion pressure in deformation process is calculated,which provides theoretical basis for reasonable selection of forming equipment and determination of process plan.The Gleeble-3800 thermal simulation machine is used to simulate the 35 Cr Mo steel used in steel tie rod.The finite element simulation software Deform-3d is used to simulate the punch velocity,deformation,temperature conduction,etc.in the process of backward extrusion the backward extrusion forming process of U-joints of 20-tye steel tie rod,and the law of metal flows,stress field,strain field,temperature field and the punch load is analyzed to guide the formulation of the process.On the basis of theoretical analysis and forming simulation,the formability experiment is carried out to verify the feasibility of the process and provide experimental basis for actual production.The original material of 35 Cr Mo steel and the metal microstructure after reverse extrusion are observed,and the microstructure changes,grain size changes,defects in the microstructure and mechanical properties changes are analyzed.The tensile tests at room temperature are carried out to analyze the mechanical properties of metals before and after back extrusion.According to the experimental results,the grain size of the product after reverse extrusion is small and evenly distributed,and the mechanical properties are greatly improved compared with the original process.By means of theoretical modeling,numerical simulation and experimental verification,this paper realizes the research of U-shaped head to reverse extrusion forming into 20-type steel tie rod,which is an important step in the research of integral steel rod forming process.