Numerical Simulation Of Stretch Reducing For Hot Rolled Seamless Steel Tubes And Development Of Simulation System

Seamless steel tube is a very important kind of steel products,and it is widely used.Since the concept of stretch reducing was put forward by J.W.Offut in 1932,many scholars at home and abroad have done a lot of research on stretch reducing technology.Now stretch reducing technology has been widely used in seamless steel tube production.Stretch reducing is the last line of hot deformation process in the production of seamless steel tube,directly determines the size precision and the quality of the finish-pipe.Stretch reducing is rather complicated,if the tension coefficient is not set accurately,the distribution of the diameter reduction is unreasonable or the pass is not reasonable,it will easily cause defects such as wall thickness,uneven wall thickness and excessive ellipticity.With the development of computer,the finite element simulation technology is widely used,but a complete simulation by using finite element method cannot be yet carried out within a reasonable time.This paper studied on these problems.At first,the development status of the stretch reducing technology and its finite element simulation at home and abroad was studied in this paper.Then,the theory of tension reduction and the three roll stretch reducing.Using the numerical calculus and derivation,the formula for diameter,coefficient of tension,wall thickness and roll speed was established.Then,according to production process of stretch reducing in a factory,a thermomechanical finite element model was established by MSC·Marc software.The comparison between simulated results and available experimental data confirms the validity of the model.Tube diameter in the process of shape evolution,stress strain field,temperature field,rolling force and rolling torque was discussed.The influence of the ovality of the pass and the distribution of the reducing diameter on the uneven wall thickness was studied.The effect of process parameters on the change of wall thickness is studied,and the reasonable process parameters are obtained.Two simple finite element models called micromodel and single-stand-model were carried out,and the micromodel model reduces the simulation time by 2/3,and the single-stand-model realized the rapid simulation.Finally,the stretch reducing FEM system was developed by means of VB,Marc,Python,Excel and other software,the system could established the finite element model and was able to predict quite well the behavior of so complex steel producing plants.The system provided a good theoretical test platform for the development of new hole shape and new products,The development cycle of the product and the cost of test rolling would be reduced.