Research and Development Trend of Shape Control for Cold Rolling Strip

Shape is an important quality index of cold rolling strip. Up to now, many problems in the shape control domain have not been solved satisfactorily, and a review on the research progress in the shape control domain can help to seek new breakthrough directions. In the past 10 years, researches and applications of shape control models, shape control means, shape detection technology, and shape con- trol system have achieved significant progress. In the aspect of shape control models, the researches in the past improve the accuracy, speed and robustness of the models. The intelligentization of shape control models should be strengthened in the future. In the aspect of the shape control means, the researches in the past focus on the roll opti- mization, mill type selection, process optimization, local strip shape control, edge drop control, and so on. In the future, more attention should be paid to the coordination control of both strip shape and other quality indexes, and the refinement of control objective should be strengthened. In the aspects of shape detection technology and shape control system, some new types of shape detection meters and shape control systems are developed and have successfully indus- trial applications. In the future, the standardization of shape detection technology and shape control system should be promoted to solve the problem of compatibility. In general,the four expected development trends of shape control for cold roiling strip in the future are intelligentization, coordi- nation, refinement, and standardization. The proposed research provides new breakthrough directions for improv- ing shape quality.

Research and Application of Non-symmetrical Roll Bending Control of Cold Rolling Mill

The existing research of the flatness control for strip cold rolling mainly focuses on the calculation of the optimum adjustment of individual flatness actuator in accordance with the flatness deviation, which can be used for general flatness control. However, it does not work for some special rolling processes, such as the elimination of ultra single side edge-waves and the prevention of strip break due to tilting roll control overshooting. For the purpose of solving these problems, the influences of non-symmetrical work roll bending and intermediate roll bending on flatness control were analyzed by studying efficiencies of them. Moreover, impacts of two kinds of non-symmetrical roll bending control on the pressure distribution between rolls were studied theoretically. A non-symmetrical work roll bending model was developed by theoretical analysis in accordance with practical conditions. The model was applied to the revamp of a 1250 6-H reversible universal crown mill (UCM) cold mill. Theoretical study and practical applications show that the coordination utilization of the non-symmetrical work roll bending control and tilting roll control was effective in flatness control when there appeared bad strip single side edge waves, especially when the incoming strip was with a wedge shape. In addition, the risk of strip break due to tilting control overshooting could be reduced. Furthermore, the non-symmetrical roll bending control can reduce the extent of uneven distribution of pressure between rolls caused by intermediate roll shifting in flatness control and slow down roll wear. The non-symmetrical roll bending control technology has important theoretical and practical significance to better flatness control.

Industrial shape detecting system of cold rolling strip

A high-precision shape detecting system of cold rolling strip is developed to meet industrial application, which mainly consists of the shape detecting roller, the collecting ring, the digital signal processing （DSP） shape signal processing board and the shape control model. Based on the shape detecting principle, the shape detecting roller is designed with a new integral structure for improving the precision of shape detecting and avoiding scratching strip surface. Based on the DSP technology, the DSP shape signal processing circuit board is designed and embedded in the shape detecting system for the reliability and stability of shape signal processing. The shape detecting system was successfully used in Angang 1 250 mm HC 6-high reversible cold rolling mill. The precision of shape detecting is 0.2 I and the shape deviation is controlled within 6 1 after the close loop shape control is input.

Backup roll contour of a SmartCrown tandem cold rolling mill

SmartCrown was a new system developed by VAI for improving the strip profile and flatness control first applied in 1700 mm tandem cold rolling mills at Wuhan Iron ＆ Steel （Group） Corporation （WISCO）. After tracing and testing, the application of the conventional crown backup roll matching the SmartCrown work roll of the production mill led to heavy and nonuniform wear, and the edge spalling of the backup roll often occurred. A 3-dimension finite element model of roll stacks was established, which was used to analyze the above-mentioned problems, and it was found that the main reason was the highly nonuniform contact pressure distribution between the work roll and the backup roll. A new FSR （flexible shape backup roll） was developed and applied in 1700 mm tandem cold rolling mills. A lot of good actual effects of FSR, such as evident improvement in profile and flatness of strips, non-occurring edge spalling, wear uniform, and remarkable decrease in roll consumption were validated by long-term industrial applications.

Improvement on strip flatness of cold temper mills by modifying roll contour shape

A study on roll gap profile (strip profile) control was accomplished in a1700 mm single-stand temper mill. Some critical problems such as the deviation of work roll contourcaused by grinding and wear, the effectiveness of work roll bending were discussed. Using a finiteelement model, the effects of roll contours (ground and wear) on strip profile were investigated.The roll bending effect on strip thickness was also analyzed. It is pointed out that there are somespecial features of flatness control in the temper mill: during temper rolling, roll deformation isslight due to small rolling load, and the loaded roll gap profile mainly depends on work rollcontour, while the backup roll has a little effect on gap crown; the effect of bending force ongauge can not be ignored due to the coupling between flatness control and gauge control. A new rollcontour arrangement adaptable to the mill was presented and has been put into practical production.The application of the new set of rolls showed some good results: larger crown control range of workroll bender, higher rolling stability, better strip profile and flatness quality.

Strip Thickness Control of Cold Rolling Mill with Roll Eccentricity Compensation by Using Fuzzy Neural Network

In rolling mill, the accuracy and quality of the strip exit thickness are very important factors. To realize high accuracy in the strip exit thickness, the Automatic Gauge Control (AGC) system is used. Because of roll eccentricity in backup rolls, the exit thickness deviates periodically. In this paper, we design PI controller in outer loop for the strip exit thickness while PD controller is used in inner loop for the work roll actuator position. Also, in order to reduce the periodic thickness deviation, we propose roll eccentricity compensation by using Fuzzy Neural Network with online tuning. Simulink model for the overall system has been implemented using MATLAB/SIMULINK software. The simulation results show the effectiveness of the proposed control.

Finite element analysis of shape control for continuous hot rolling mills of super wide strip steel

The efficacy of shape control is the core of this technology and the main basis of automatic shape control system model designing. This passage constructs the three-dimensional elastic deformation model of CVCplus roll system in 2250 mm hot rolling mill. Comparing and analyzing different influence of working factors on control characteristic, the shape control characteristic of CVCplus roll system in its whole work time is studied, and the cause is analyzed and the difference of the roll gap curve and crown adjustable area in early and latter work time is compared. The outcome has crucial meaning in both theory and production.

DECOUPLED MODEL FOR FLATNESS CONTROL IN 4-H CVC COLD ROLLING MILLS

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Controlled Rolling and Cooling Process for Low Carbon Cold Forging Steel

Effect of controlled rolling and cooling process on the mechanical properties of low carbon cold forging steel was investigated for different processing parameters of a laboratory hot rolling mill. The results show that the specimens with fast cooling after hot rolling exhibit very good mechanical properties, and the improvement of the mechanical properties can be attributed mainly to the ferrite-grain refinement. The mechanical properties increase with decreasing final cooling temperature within the range from 670 ℃ to 570 ℃ due to the finer interlamellar spacing of pearlite colony. The specimen with fast cooling after low temperature rolling shows the highest values of the mechanical properties. The effect of the ferrite grain size on the mechanical properties was greater than that of pearlite morphology in the present study. The mechanical properties of specimens by controlled rolling and cooling process without thermal treatment were greatly superior to that of the same specimens by the conventional rolling, and their tensile strength reached 490 MPa grade even in the case of low temperature rolling without controlled rolling. It might be expected to realize the substitution medium-carbon by low-carbon for 490 MPa grade cold forging steel with controlled rolling and cooling process.

Adiabatic cooling for cold polar molecules on a chip using a controllable high-efficiency electrostatic surface trap

We propose a controllable high-efficiency electrostatic surface trap for cold polar molecules on a chip by using two insulator-embedded charged rings and a grounded conductor plate. We calculate Stark energy structure pattern of ND3 molecules in an external electric field using the method of matrix diagonalization. We analyze how the voltages that are applied to the ring electrodes affect the depth of the efficient well and the controllability of the distance between the trap center and the surface of the chip. To obtain a better understanding, we simulate the dynamical loading and trapping processes of ND3 molecules in a ｜J, KM = ｜1,-1 state by using classical Monte–Carlo method. Our study shows that the loading efficiency of our trap can reach ～ 88%. Finally, we study the adiabatic cooling of cold molecules in our surface trap by linearly lowering the potential-well depth（i.e., lowering the trapping voltage）, and find that the temperature of the trapped ND3 molecules can be adiabatically cooled from 34.5 m K to ～ 5.8 m K when the trapping voltage is reduced from-35 k V to-3 k V.

Optimal Control of a Tandem Cold Rolling System for Tracking Problem

The optimal control principle and procedure of a tandem cold rolling system for tracking problem have been proposed in this paper for the first time. The state-space description of the tandem cold rolling system for the cold-strip mill of Wuhan Iron and Steel Company is: x_(k+1)=Ax_k+(_k,y_k=Cx_k+η_k The optimum performance index of the system for tracking problem is: J_(min)=minEr[(1/2)sum from k=0 to m e'_kOe_k sum from k=0 to m-1 u'_kRu_k] The authors have deduced the optimal control of the system for tracking problem as follows u_k~*=-S_k(Ay_k+_(k+1)-) the feedback gain matrix S_k is given by S_k=(B'P_(k+1)B-R)^(-1)B'P_(k+1) Pk satisfies the matrix difference equation p_k=P_(k+1)-[(S_k^(-1))'-B']^(-1)R(S_k^(-1)-B)^(-1)+Q with terminal condition P_m=Q. On the above-mentioned principle of optimal control,an optimal control procedure of the tandem cold rolling system has been obtained, and a computer simulation has been performed. The results of the simulation are satisfactory.

Cold-rolling technologies of advanced high strength steels in Ansteel

Low - carbon becomes a high - frequency and fashionable word which gets the greatest concern in the world.Low - carbon refers to a minimal output of greenhouse gas emissions into the biosphere, specifically refers to the greenhouse gas carbon dioxide.To reduce energy consumption of automobile,more and more high strength steels are used by vehicle companies.To meet the request of vehicle companies, various high strength steels are developed in steel companies all over the world.Ansteel can provide,ultra-low carbon bake hardening(BH) steels,dual phase(DP) steels and transformation - induced plasticity (TRIP) steels with the grades of under 780 MPa,up to now.AHSS steels have much different composition, microstructure and strenght than conventional vehicle steels,so there are some trouble in producing in cold rolling mills,for example,difficult to join,poor thickness and flatness,accurate temperature and velocity control and so on.To reduce the opportunity of strip breakage,we have done many welding experiments and special research.Now,DP and TRIP steels can be continuously produced in Ansteel.To assure thickness and flatness of strips,we optimized the hot rolling parameter to get low deformation resistance,optimized rolling oil to get fit frictional coefficient and fix on the targat rolling curve.To get more accurate and repetitive results over the production shifts,the Mathematical Model(MM) is used in Ansteel.The MM analyses information transmitted by various sensors and transmitters,compares the collected data with the chosen parameters and adjusts the settings of the various pieces of equipment to hone on the parameter setpoints.At present,the key production technologies of AHSS were grasped by cold rolling mill Ansteel,and Ansteel is the first company to apply the TRIP with the grade of 780 MPa.

Development and application of cold strip rolling flatness control system in Ansteel

In this paper,the flatness control technology AnShaper^(TM) for cold-rolling mill and industry application are introduced.AnShaper^(TM) includes;partitioning piezomagnetic shape meter for flatness measurement for cold-rolling strip;flatness measured signals processing system based on digital signal processing(DSP);flatness feedback control model system based on the control efficiency of flatness control actuators and model adaptive function.The application verifies that strip flatness can meet the need of high quality product by using AnShaperTM.The average flatness quality is about 5Ⅰ-unit and the 0.18 mm ultrathin thickness strip flatness is 10Ⅰ-unit.

Hourglass Control in Dynamic Explicit Simulation of Cold Ring Rolling Process

Hourglass is remarkably aroused in ring rolling simulation with reduced integration element because of violent ring vibration and small contact area of ring with forming rollers. Hourglass energy can be reduced by improving mesh density. Combined approach of artificial damping and artificial stiffness can control the hourglass. A ring with rectangular section is simulated with the weight factor of artificial stiffness resistance set to 0.2. The artificial damping hourglass control coefficient is set to 0.1, and the artificial stiffness hourglass control coefficient is set to 0.001. The ratio of hourglass energy to internal energy is reduced to 2.5 percent. Compared with axial spread width test, the effectiveness of hourglass control in ring rolling simulation is verified.

厚板轧制过程轧件翘扣头控制的有限元研究

利用ABAQUS有限元软件,模拟了厚板的轧制过程,计算了一系列可调控的工艺参数对轧件翘扣头的影响。可调控的工艺参数主要包括轧制中心线位置H i、上下轧辊的辊速差S k i和轧件上下表面温度差ΔT。计算结果表明,通过调整H_(i)、S_(ki)和ΔT,可以分别在2 m长度轧件上获得-17.5 mm、-181.0 mm和-200.0 mm的翘扣头控制量。进一步的分析表明,调节上下辊的辊速差、轧件上下表面温度差可较为有效地控制轧件翘扣头,且上下表面温度差对轧件翘扣头的控制能力更强。

安钢冷轧1550 mm连退炉内张力控制与分析

结合安钢冷轧连退机组实际工艺流程,以安钢冷轧1 550 mm连退机组退火炉为研究平台,分析与研究了其炉内带钢张力,这对于薄带钢高速运行低张控制优化具有一定指导意义,可实现冷轧连退薄带钢高效化生产。

冷连轧弯辊力精度改进PSO-SVM预测及补偿分析

为了进一步控制冷连轧弯辊力精度,构建改进PSO-SVM预测模型。利用包含压缩因子的粒子群算法完成支持向量机参数的更高效寻优处理,对回归轧制参数实施反归一化获得弯辊力模型。根据现场实际轧制结果完成预测模型的验证过程。研究结果表明:采用改进PSO-SVM模型获得的预测性能指标在上述优化方法中达到了最低,改进PSO-SVM模型具备最优预测效果。设置可靠补偿后大幅降低了AFC系统工作量,促进了带钢板形效率的显著提升。弯辊力补偿值形成了与弯辊力几乎相同的变化规律,具备优异预测性能。

1180 MPa级超高强钢冷连轧过程的厚度综合控制技术

针对超高强钢在冷轧过程中厚度波动大以及带头带尾厚度超差的问题,首先根据金属秒流量模型建立了厚度超差预测模型与辊缝调节量预估模型;随后开发了轧制过程中的厚度控制系统,并进行了辊缝调节量优化;最后建立了带钢头尾轧制过程中的轧制速度与张力优化模型。以国内某冷连轧机组的第1机架为技术应用对象,选择两种典型的超高强钢进行生产测试,测试结果表明:超高强钢AR4146E1与DU6220A1的厚度超差长度分别从70.3 m、36.89 m下降到了16.85 m、16.33 m。

On the Innovation,Design,Construction,and Experiments of OMEGA-Based SSPS Prototype:The Sun-Chasing Project

This study systematically introduces the development of the world’s first full-link and full-system ground demonstration and verification system for the OMEGA space solar power satellite(SSPS).First,the OMEGA 2.0 innovation design was proposed.Second,field-coupling theoretical models of sunlight concentration,photoelectric conversion,and transmitting antennas were established,and a systematic optimization design method was proposed.Third,a beam waveform optimization methodology considering both a high beam collection efficiency and a circular stepped beam shape was proposed.Fourth,a control strategy was developed to control the condenser pointing toward the sun while maintaining the transmitting antenna toward the rectenna.Fifth,a high-efficiency heat radiator design method based on bionics and topology optimization was proposed.Sixth,a method for improving the rectenna array’s reception,rectification,and direct current(DC)power synthesis efficiencies is presented.Seventh,high-precision measurement technology for high-accuracy beam-pointing control was developed.Eighth,a smart mechanical structure was designed and developed.Finally,the developed SSPS ground demonstration and verification system has the capacity for sun tracking,a high concentration ratio,photoelectric conversion,microwave conversion and emission,microwave reception,and rectification,and thus satisfactory results were obtained.

电磁调控轧辊的热力胀形行为及高效控制方法

为研究辊形电磁调控技术(roll profile electromagnetic control technology,RPECT)的热力胀形行为,采用有限元方法分析了不同电流密度及频率下综合辊凸度、热力贡献辊凸度以及力凸度占比等随接触区热量的变化规律,探究了接触区热量与热力胀形能力的映射关系及其成立条件.结果表明,在接触区热量的中低取值范围内,同一接触区热量所对应的热力调控能力不会受磁参数影响,故提出将接触区热量作为输入参数与调控能力之间桥梁的RPECT高效控制策略.该策略通过提升磁参数来快速达到接触区的目标温升效果,进而获取目标调控能力.以20μm的辊缝凸度需求为例,经原始与高效控制策略间的对比发现,新策略的调控时间可有效地缩短至原调控时间的19.57%.