Study And Application Of High Accuracy Camber Control In Plate Rolling

To the camber of rolled pieces problems by asymmetric influencing factors existed in plate production process, this paper puts forward camber prediction and control model, the on line correction method of temperature prediction, the self-learning method of deformation resistance and influence function method were analyzed. The Application software included camber measurement, camber prediction and camber control were developed based on the machine vision technology, and has obtained very good results in the on-line application of production practice.(1) The high accuracy prediction of temperature was realized in plate production process. The temperature evolution model of plate production have been built based on implicit difference method and finite element method, and determine the heat transfer coefficients of different conditions. According to the characteristics of plate production, the approach to the real temperature measuring method of rolled pieces were proposed on the basis of the verification each other between prediction and measured temperature. The method constantly study to the model parameters in measuring temperature of rolled pieces, and ensures the measured accuracy.(2) The self-learning system of deformation resistance was developed based on genetic algorithm. The model parameters value of deformation resistance determines the prediction accuracy of rolling force model. According to the influencing factors analysis of rolling force calculation error, the genetic algorithm were introduced the self-learning method of deformation resistance, and search the optimal value of deformation resistance on the basic of space exploration and optimization ability of genetic algorithm. The decision variable selection, the coding and decoding, the fitness evaluation and the terminal conditions process were implemented during development process of self-learning system. The results show that the optimization speed and accuracy can meet production requirement.(3) A camber predictive method of plate rolling was put forward. The theoretical formulas that predict the camber curvature of rolled piece were derived on the basis of the movement characteristics of rolled piece. In combination of temperature model and rolling force model, the section thickness distributions of rolled piece were calculated by using of improved influence function method for adaption to width variations. The camber predictive model for the improved influence function method coupling with camber theoretical formulas can analyze the effect of asymmetry factors on camber of rolled piece.(4) An on-line calculation method of plasticity coefficient was put forward. Based on the rolling theory model, a plasticity coefficient curve was fitted by using conic according to the inaccurate or unstable problems of plasticity coefficient calculation. The plasticity coefficient can be obtained by the tangent slope at reduction amount of conic. The process method does not depend on process control computer, and can be embedded into basic automation system immediately. According to the change of rolling force and roll gap, the plasticity coefficient can be adjusted constantly, and improves the compensation precision of AGC system.(5) A supporting platform of process control was developed and was used on-line. According to the research of process control system, a supporting platform of process control, based on the separated structure between communication process and model process, was developed on the basic of the analysis of system functional requirement. The platform encapsulates the communication procedure, and establishes system architecture based on event scheduling, suitable to programming and debugging, it has been applied to plate production line successfully, and greatly promote development efficiency of process control system.(6) A measured method of plane dimension was presented for plate rolled piece. A measured scheme was presented on the basic of the measuring characteristic of plane dimension for plate rolled piece. The camber measuring system, based on machine vision technology including gray histogram equilibrium, fast median filter, Sobel operator edge detection, Hough line detection, sub-pixel edge location using spatial moment and eight point’s calibration method, is established. The measuring results show that the measuring accuracy can meet the project requirements.(7) The concept of equivalent rolled piece was given, and applied to the camber control of rolled piece. The asymmetry factor can be replaced by using an equivalent rolled piece, which is located in rolling centerline, and has a certain amount wedge. The camber control way between actual and equivalent rolled piece is the same. The process way unifies asymmetry factor, and carries out calculation and control conveniently.(8) The Application software of camber detection and control was developed on the basic of camber model, section shape calculation model and plane dimension measuring model. The software implements on-line application of camber control, and can restricts the camber curvature of rolled piece in a certain scope, and improves finishing product rate.Under the background of the development of plate rolling in our country, this dissertation carried the analysis of camber phenomenon of plate rolling. The camber detection and control software for plate mill was developed, and it improves the plate production level of our country.