Steel strips are the main of steel products and flatness is an important quality indicator of steel strips. Flatness control is the key and highly difficult technique of strip mills. The bottle-neck restricting the improvement of flatness control techniques is that the research on flatness theories and control mathematic models is not in accordance with the requirement of technique developments. To build a simple, rapid and accurate explicit formulation control model has become an urgent need for the development of flatness control technique. This paper puts forward the conception of dynamic effective matrix based on the effective matrix method for flatness control proposed by the authors under the consideration of the influence of the change of parameters in rolling processes on the effective matrix, and the concept is validated by industrial productions. Three methods of the effective matrix generation are induced: the calculation method based on the flatness prediction model; the calculation method based on the data excavation in rolling processes and the direct calculation method based on the network model. A fuzzy neural network effective matrix model is built based on the clusters, and then the network structure is optimized and the high-speed-calculation problem of the dynamic effective matrix is solved. The flatness control scheme for cold strip mills is proposed based on the dynamic effective matrix. On stand 5 of the 1 220 mm five-stand 4-high cold strip tandem mill, the industrial experiment with the control methods of tilting roll and bending roll is done by the control scheme of the static effective matrix and the dynamic effective matrix, respectively. The experiment result proves that the control effect of the dynamic effective matrix is much better than that of the static effective matrix. This paper proposes a new idea and method for the dynamic flatness control in the rolling processes of cold strip mills and develops the theory and model of the flatness control effective matrix method.
Using the effective matrix methods of flatness and profile control synthetically, the flatness and profile integration control scheme for tandem cold mills is built in order to increase flatness and profile control precision of tandem cold mills. Corresponding control strategies are adopted for various control objectives of different stands and the coordination control strategies of various stands are given, which makes the on-line flatness control cooperate with on-line profile control and implements the parallel control of different stands. According to the measured flatness and profile data of some 1550 mm tandem cold mills, the control scheme is verified and the result indicates that the scheme has high flatness and profile control precision with steady and reliable control process. A new way and method is supplied for researching shape control of tandem cold mills.
SHAN Xiu-ying1,2,3, LIU Hong-min1,2, JIA Chun-yu1,2, SUN Jian-liang1,2 (1. Engineering Research Center of Rolling Equipment and Complete Technology of Ministry of Education, Yanshan University, Qinhuangdao 066004, Hebei, China
There are very few researches on the shape standard curve currently,and they merely remain on the level of description of the general concept and production experiences,lacking of the in-depth theoretical analysis,and the concrete principle,method and steps for determining the shape standard curve are not put forward,therefore,they are not applicable in industrial production.This is the weakest spot in the research on the basic shape theory.In this paper,the basic shape standard curve and the transverse distribution curve of the exit thickness are attained with stepwise optimization,which is based on the theoretical calculation method of the shape standard curve of strip mills proposed by authors.By calculating the shape discrimination model and the shape forecast model separately,the simultaneous iterative calculation by the previous method is avoided,and the speed and stability of calculation are improved.The compensation models of the transverse temperature difference of the strip,the shape detection roller deflection and the shape of the strip coil are established,respectively,meantime,the basic shape standard curves are compensated,and the relatively perfect theoretical establishment method of the shape standard curve is formed.The simulation and calculation are done on a 1 220 mm five-stand cold strip tandem mill.The simulation and calculation result shows that the principle,method and steps for determining the shape standard curve are correct and feasible,and the correctness of theoretical analysis and calculation is verified.This paper proposes an idea and a method for the establishment of the shape standard curve in the rolling processes of cold strip mills,which develop the theory and model of the shape standard curve and improve the quality and efficiency of the shape control in the rolling processes of cold strip mills.
Some unavoidable factors in the process of cold strip shape measurement interfere with the shape meter,so the shape measuring results cannot reflect the true shape of the strip and the measuring precision is low. The influences of the measuring error of the strip edges, the transverse temperature difference of the strip, the deflection of shape detection roller, and the shape of the strip coil on the shape measuring results were analyzed in detail, and the corresponding compensation models were established.The simulation calculation and analysis were carried out on a cold strip mill,and a number of disciplinarian cognitions were obtained.
YU Bing-qiang SUN Ya-bo LIU Hong-min YOU Lei PENG Yan
The shape and thickness qualities of strip are influenced by the vibration of rolling mill.At present,the researches on the vibration of rolling mill are mainly the vertical vibration and torsional vibration of single stand mill,the study on the vibration of tandem rolling mill is rare.For the vibration of tandem rolling mill,the key problem is the vibration of the moving strip between stands.In this paper,considering the dynamic of moving strip and rolling theory,the vertical vibration of moving strip in the rolling process was proposed.Take the moving strip between the two mills of tandem rolling mill in the rolling process as subject investigated,according to the theory of moving beam,the vertical vibration model of moving strip in the rolling process was established.The partial differential equation was discretized by Galerkin truncation method.The natural frequency and stability of the moving strip were investigated and the numerical simulation in time domain was made.Simulation results show that,the natural frequency was strongly influenced by the rolling velocity and tension.With increasing of the rolling velocity,the first three natural frequencies decrease,the fourth natural frequency increases;with increasing of the unit tension,when the rolling velocity is high and low,respectively,the low order dimensionless natural frequency gradually decreases and increases,respectively.According to the stability of moving strip,the critical speed was determined,and the matching relationship of the tension and rolling velocity was also determined.This model can be used to study the stability of moving strip,improve the quality of strip and develop new rolling technology from the aspect of dynamics.
