Application of DEFORM-3D Finite Element Analysis in Optimization Design for Steel Rolling Production

Transcription

1 Application of DEFORM-3D Finite Element Analysis in Optimization Design for Steel Rolling Production *1,Jianhua Ren 1 Jianhua Ren, 2 Wei Wang, 3 Rong Liu Hebei University of Engineering, renjianhua1974@163.com 2,Wei Wang Hebei University of Engineering, wangwei@hebeu.edu.cn 3, Rong Liu Xingtai iron &steel Co. LTD. liurongxt@sina.com Abstract. In this paper, DEFORM 3D finite element analysis program is used as work platform, the high-speed wire rod rolling process of φ20 bar as the research object to be simulated numerically, using the method of simulation analysis optimization to research. The first step work of the 12 rolling process is as an example to show the simulating process and results. The stress field, strain field are simulated in the process of high speed wire rod rolling.through analysis, the defects of rolling technology were found out. Therefore, the optimum design is gotten and then simulated which improved the actual production process and avoided the original defects. So the optimum design is proved feasible in groove design and the optimization of process parameters in the production process. The paper is trying to find out the law of three-dimension metal flow in the rolling process of high-speed rod and summarize the regularity of the metal deformation. Some viewpoints are proposed about the correct pass design and the technical parameter of optimization in producing process. Keywords: High-speed wire steel rolling, Finite element simulation, Parameter optimization 1. Introduction Optimization of technology is always an objective people to seek. With the development of computer and production, it s become one of the new research fields that optimize technology uses simulation to simulate metal forming presses. In various numerical simulation methods used in metal forming process, finite element method is thought to be the most popular one that can be used in every field. Simulation of metal forming process with FEM is one of important study content in research of metal forming theory. With this method, man can correctly reveal the essence of section steel deformation, master the relations existed in much parameters which influence metal deformation, resolve radically problem that design of metal forming is too much dependent on experience and blindness when develop new product. So the reliability and science of pass design can be enhanced [1] [2]. In the field of metal forming simulation, with the increasing of people's needs, there were a lot more mature commercial simulation softwares which are convenient for researchers using numerical simulation technique to study the industrial process [3][4]. DEFORM is a finite element process simulation system to be applied for the analysis of metal forming and various forming process in related industries and heat treatment process [5][6]. In the high-speed wire production line, square billet is just as raw materials which are high-quality S45C carbon steel. The whole production line includes 12 rolling processes under the temperature of 1180 to 1070 At. the end of the No.12 process, φ20 bar,which thoroughly is achieved the expected goal of design,is formed. 2. Research Method This paper took the high-speed wire rod rolling process of φ20 bar as the research object, to be simulated numerically under the work platform of the finite element software DEFORM. The Journal of Convergence Information Technology(JCIT) Volume8, Number10, May 2013 doi: /jcit.vol8.issue

2 simulation results were compared with the actual operation of the production process, the rolling simulation reappeared the actual production situation, realized the visualization of the rolling process. 2.1 Optimal design process d d=20±0.35mm out of roundness of 0.56 (mm) Figure 1. The standard size of round bar steel At first, the 12 processes of the original production are simulated and analyzed. Next, the deformation parameters and temperature parameters and results, including the rolling speed, rolling load, rolling geometry, the final product of the force and energy parameters of the original process, are detected on-line. The original process simulation and actual operating conditions are comparative analyzed, and the simulation experience is summarized. Then it is to find defects, optimizing production and simulating. The related parameters are detected on-line. In the end, two simulated rolling production results and actual results are analyzed. The standard size of round bar steel that is simulated in this paper is as figure The finite element grid layout According to the deformation condition of steel and violence of different rolled parts of the cross section deformation, the finite element mesh can be confirmed. In the length direction of rolled piece, unit number is according to the rolled piece length and the average unit size of cross section. To meet the requirements of precision, it needs to reduce unit number. According this principle, in different type of finite element mesh, number of units is about 3000 ~ 6000 respectively. 2.3 The friction boundary conditions In the steel rolling process, the mechanism of friction between metal and deformation tools is very complex. The mechanical properties of the work piece, interface condition of the tool and work piece, deformation temperature, and deformation force of friction have great influence on the friction. To simplify the calculation, in this paper, is assumed that only dry friction exists between tool and work piece. The friction coefficient complies with coulomb friction law that is unit friction is proportional with positive pressure of contact surface. Empirical formula calculation method is adopted in this condition. The formula is as the following: f t v (1) f friction coefficient; t rolling temperature ; v rolling speed m/s The formula is suitable for hot rolling process on cast steel with normal speed. 2.4 The definition of initial contact point 684

3 The definition of the initial contact point between the blank and roll determine rolling process smoothly or not. Otherwise it will penetrate the contact body or make the rolled-piece deflection to enter roll difficultly. Simple section steel has two axis of symmetry, rolling piece in horizontal and vertical direction location is fixed. It is needed to push the rolled-piece in roll gap to establish rolling process when calculating. The initial point of contact can be calculated from the shapes of the materials and the pass and be derived by geometric relations [9][10]. The first one in the opening round steel billets is to confirm the contact point between the roller and square blank according to the pass rolling chart to calculate point of a. Then actual roll work roll diameter of rollers contact point can be calculated for bottom rollers contact points with the top roller contact point are symmetric, just as figure2. Figure 2. Schematic diagram of the initial contact point Figure 3. The show of NO.1 process The distance from the initial contact surface to the surface of the axis of the upper and lower roller is x, the lower roller axis iso 2, then: r1 x a O1O 2 (2) 685

4 Application of DEFORM-3D Finite Element Analysis in Optimization Design for Steel Rolling Production O1O2 is the distance between the axis of the upper and lower rollers. Thus x can be solved from the equation. Then the vertical distance from the upper and lower rolls contact point to the axis can also be derived. The distance between top roller contact point and the roll axis is y1 2 y1 r1 r1 x2 (3) The distance between under roller contact point and the roll axis is y2, y2 = y1 By a, y1, y2, the initial contact position of the work piece can be determined when being rolled, then model will be established. 3. Simulation method This paper simulates the deformations of NO.1 to 12 processes. In order to accurately reflect the whole rolled-piece deformation, the ingressive material size is the primitive billet size. The calculated results from ingressive material shapes and sizes of NO.2 ~ 12 processes through every process can also be recorded as the ingressive one of the next process. The models are re-established and the grids are divided again according to the shape of the incoming material before the next process simulation [3] [4].Through above method, deformation in whole process can be reflected entirely. NO.1 process is an example just as Figure3. 3.1Computer simulation of rolling process According to the original parameters of equipment, material in the initial process, rolling production is simulated using DEFORM program. The simulation results include the equivalent strain, equivalent strain rate field, the main stress field, such as stress field, equivalent strain field, rolling force, rolling torque, temperature field and so on. Figure 4 shows effective strain distribution, figure 5 is the change of rolling moment in NO.1 rolling process. Figure 4. Effective strain distributions Figure 5. Change of rolling moment 686

5 Figure 6. Rolled-piece sampling size in actual production Figure 7. Simulation size 3.2 Analysis of simulation results Figure 6 is the rolling sample size in the actual production, figure7 is obtained by rolling simulation size, the simulated results and actual results vary slightly. In actual production, bumps appear in the first rolling process, this phenomenon is also reflected in the simulation process. Simulation shown the actual production rolling case achieves the visualization of the program for reasonable production and provides a reliable basis. Table 1 is the main process parameters of the actual rolling process, the rolling process simulation and those of the design. Comparing the three groups, edge of the design value is so idealized that caused error. The bump of the first process must be fixed to reduce the adverse effects to subsequent process. Table 1. Main process parameters of rolled-piece about the actual rolling production, the rolling simulation and initial design process Actual rolling (mm) Simulation rolling(mm) Initial design (mm) Height Width Height Height Height Width

6 The principle of process optimization Through the comprehensive analysis on the computer simulation results and actual rolling, it can be concluded: the production process must be optimized to meet the actual production needs. The success of rolling simulation provides the reliable basis and experience for process optimization. Optimization principles: to maintain the existing system and the roll pass design configuration, by modifying the cutting process pass to achieve optimization, the process should be modified to eliminate or reduce the original process insufficient to achieve the width and height to meet the needs of the later process so that the final products meet standards. 4.1Analysis of the optimized parameters The equivalent stress is shown the first pass in Figure 8; the maximum principal stress is shown in figure 9. It can be seen in the figure, when the rolling contact with rollers (upper roller), the first contact with the regional roll has a lot of stress, due to the corner rolling deformation in rolling the largest, therefore, this area shows a great deal of stress; with the distortion of the depth, the compressive stress extends to the upper part of rolling. In the middle and later deformation, rolled-piece gradually is filled in the roller side of the upper corner. 4.2Analysis of simulation and optimization process After optimization in the simulation, the pump does not exist in first rolling process and this phenomenon has been tested in the actual production process as shown in Figure 10 and 11. In rolling process simulation, the metal flow has been optimized to avoid pumps. In the following 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 processes, the rolling state and shape are ideal. Figure 8.Equivalent stresses after optimization Figure 9. The maximum principal stress optimization 688

7 In table 2, geometric parameters of the actual rolling process after optimization, simulation of rolling process after optimization and initial design process are compared together in every process. Figure 10. Simulation of optimized size Figure11. Optimized actual sample size Table 2. Main process geometric parameters of rolled-piece about actual rolling process after optimization, simulation of rolling process and the initial design process Actual rolling(mm) Simulation rolling(mm) Initial design (mm) Height width height width height width Conclusion Firstly, based on actual production conditions, it could determine the mesh partition, the initial contact point and friction treatment. The simulation and optimization of the original process rolling prove the feasibility. Secondly, the results of computer simulation of the original process are consistent 689

8 with the actual production situation, the simulation results clearly show the metal deformation process, which provides a reliable basis for process optimization. Thirdly, the simulation and optimization by finite element analysis program DEFORM have been verified in the actual production and realized the visualization of rolling process, which indicates the feasibility of finite element analysis program DEFORM application for the analysis of rolling process. References [1]XU Rutao,Huang Hailing,Wang Kelu,LI Bin, Bound of Guide Roll in Radial-axial Ring Rolling Finite Element Simulation Based on Deform-3D, Hot Working Technology, vol.41, no.3, pp.87-91, [2]CHEN Qi-dong1,WEN Hua-bing, Finite elements analysis for sheet stamping process based on Deform-2D, Machinery Design & Manufacture no.3, pp ,2011. [3]BAI Hua, MENG Xian-ju, CHEN Lian-sheng, LI Xiao-bo, Numerical Simulation and Failure Analysis of Rod Hot Rolling Process Using DEFORM, Journal of Hebei Polytechnic University(Natural Science Edition) vol. 30, no. 2, pp.12-15, [4]Peng Wenwen, ZENG Weidong, KANG Chao, WANG Tengfei, TIAN Fei, Development and Application of Materials Database of Finite Element Simulation Software Deform, Materials Review,vol. 25, no. 4,pp , [5]KANG Yonglin, CHEN Jiping, Development of Overseas Steel Rolling Technology, Steel Rolling, vol.26 no.1, pp.53-56, [6]Ruiliang Zhang, The Influences of Installation Errors on Double Circular Arc Tooth Spiral Bevel Gear Using TCA Method,Journal of Convergence Information Technology, Vol. 7, No. 1, pp.1-10, [7]LIU Hua,GU Ting-quan, MIAO Ming-hua, Transversal Thickness Deviation Detection and Characteristic Parameters Identification of Strip, Journal of Iron and Steel Research, vol. 24, no. 2, pp.59-62, [8]ZHU Xue-song, ZHU Guo-hui, MAO Wei-min, Comparison of Grain Size in Plain Carbon Hot-Rolled Sheets Manufactured by CSP and Conventional Rolling Processing, Journal of Iron and Steel Research,vol. 5, no.1, pp.38-42, [9]Xiang Liu, Jinhai SUN, Yaping HE, Yimin LIU, Li CAO, Overview of Virtual Reality Apply to Sports, Journal of Convergence Information Technology, Vol. 6, No. 12, pp. 1-7, [10]XU Jiang qin, Analysis of Stress Status Modulus and Shape Parameter of Transforming Field in Steel Rolling, Journal of Nanchang College of Water Conservancy and Hydroelectric Power, vol.3, no2, pp.19-22,