Fast Prediction And Application Of Finite Element Temperature Field In Hot Rolling Process Of Different Cross-section Shape Steels

During hot rolling,the temperature has an important influence on the rolling energy parameters and the microstructure and properties of the finished product.The construction of quick and accurate temperature online prediction model is of great significance for the realization of intelligent manufacturing in the rolling process.Based on the heat conduction finite element theory and the condition of calculation accuracy,this paper tries to shorten the response time of temperature prediction as much as possible,and then construct an on-line prediction model.The main research work is as follows:(1)Based on the heat transfer principle and actual rolling process,the research concentrates on the mathematical relationships among the process parameters of the rolling production line,the calculation formulas of heat transfer coefficient and as well as the internal heat source are included,developing the finite element program for solving the temperature field of air cooling process and water cooling process like bar,plate,and H-beam etc.Taking the bar as the research point,the solution time of the air cooling temperature is only 15.625 ms,the maximum difference of absolute temperature calculated is 38.3?,and the maximum relative error is 5.5%;Besides,the maximum relative error calculated in the water-cooling program is higher than 300?,which is 3.75%.Both of them meet the requirements of the accuracy and speed of the temperature field calculation in online production.(2)Taking the bar as the research object,the affecting rules of meshing methods on transient temperature oscillation,temperature convergence and calculation speed are studied.Here come to the results that when the number of grids in the air cooling process reaches 200,the calculation speed is faster and the calculation accuracy is higher,which is the optimal number of grids;Based on the element edge length and time step,the conditions for eliminating temperature oscillations are proposed;The parameters are reduced by 10 times compared with the conditions in ANSYS software,which means that the program has better calculation stability;What's more,the layer-by-layer subdivision mesh can effectively restrain the temperature oscillation and improve the program operation speed and calculation accuracy(the calculation accuracy is improved by 0.21%);Furthermore,the specific conditions for eliminating the temperature oscillation are analyzed.Among them,the radial length of the edge element of the proportional method is 8.6 times than that of the equal difference mode.Narrowing the numbering gap of adjacent nodes in the unit can reduce the bandwidth of the coefficient matrix and improve the computational efficiency by about 22%.(3)In order to realize the solution of temperature field and dynamic meshing in continuous rolling process,newton quadratic optimal interpolation is proposed after studying and analyzing the interpolation methods such as inverse interpolation,polynomial interpolation(Lagrange interpolation,Newton interpolation)and piecewise interpolation method,which avoids the ill-conditioned properties of high-order interpolation polynomials and saves calculation time under the condition of ensuring accuracy,therefore to complete the design and programming of interpolation program.Taking the rolling deformation process of the bar as a research object,the thermal effects caused by plastic deformation work and friction has been comprehensively considered.The interpolation program is utilized to develop a temperature field simulation program for the hot rolling deformation process of the bar,and then the anti-red phenomenon is analyzed and explained.(4)The graphical user interface was developed by using Python language,which successfully realized the prediction and optimization of the temperature field during the hot rolling process of different sections of steel,transforming the self-made finite element program of this research into special temperature field simulation software.The process parameters and measured temperature field data of the actual rolling process of the bar were collected,and the self-developed finite element prediction software was used to predict the hot rolling process temperature of the finished product with a size of ?22 mm.The absolute temperature deviation is 13?,the maximum relative error is about 1.4%,and the calculation accuracy is enough.Under the condition that the total number of units is 50,the calculation time of the entire rolling process is about 200 ms,and the calculation efficiency is admirable.Therefore it fully meets the requirements of accuracy and speed of online prediction of actual production.