| Due to the merits of energy conversation and emission reduction,high rate of finished product and simple production process,the Direct Rolling with Free Heating for Bar and Rod Mill has been widely used in the setting up and updating the bar and wire rod production line,which has increasingly replaced the traditional production process.The rough rolling process is a key process in the direct rolling process of bar and wire rod.It is necessary to establish an accurate mathematical model of the rough rolling phase because the start rolling temperature is lower than other procedures and the rolling force is increased.This paper combines actual manufacture for the 120 tons-third direct rolling for bar production line of Chengsteel,using ABAQUS finite element software to establish a three-dimensional coupled thermo-mechanical finite element model in the rough rolling process according to the data from actual production,further analyzes the deformation results,velocity field,temperature field,equivalent plastic strain and rolling torque,etc in the rolling process,which has a guiding significance to make a more reasonable rolling procedure.The main work of this paper is as follows:(1)According to the composition of field materials,thermophysical and mechanical performance parameters of materials were calculated by JMat Pro,providing accurate original data for numerical simulation.This paper introduces the 120 tons-three direct rolling for bar production line of Chengsteel.simply and analyzes updating process of the production line.The technological procedure of the direct rolling process is described,and the model parameters,material parameters,initial and boundary conditions are described.The finite element model of the rough rolling process of direct rolling is established according to the actual production process.(2)Aiming at the problem that it is difficult to directly solve the average temperature of rolling piece after rolling,the script which is used is realized for solving the average temperature of rolling piece in any region directly and recording the change of the average temperature with time,which ensures the accuracy of solving the average temperature.(3)According to the simulation results of rolling process by ABAQUS software,the deformation results,velocity field,temperature field,equivalent plastic strain and rolling moment during rolling process are analyzed in depth.The law of temperature variation of each layer in thickness direction is found to be divided into three stages.By analyzing the cross sections of the rolled piece,the positions of the highest temperature region of the head and steady rolling section of the rolled piece and the corresponding positions of the highest plastic strain of the head and steady rolling section of the rolled piece are determined.Compared with field data,the reliability of the model is verified.(4)By analyzing the proportion of heat transfer in the total heat change during rolling,it is concluded that the energy of heat conduction accounts for the largest proportion,followed by the heat generated by plastic deformation.By calculating the head and tail temperature of the rolled piece after the first pass,it is found that the head and tail temperature difference decreases from 50 ? to about 30 ?.The influence of rolling speed,roll diameter and elongation coefficient on the head and tail temperature difference of the rolled piece is further analyzed.Through the finite element simulation analysis of bar rolling process,the influence of rolling speed,roll diameter and elongation coefficient on temperature field during rough rolling stage,i.e.high temperature section,is basically mastered,which is helpful to optimize the process parameters of direct rolling and reduce the performance difference caused by temperature difference between the head and tail of the rolled piece. |
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