| Strip shape theory and controlling technology is a hot topic in the field of strip rolling, it has always been highly attention of researchers and production enterprises. Currently, research of the symmetric shape control technology has been relatively mature. Due to the complexity of generation mechanism, and a large number of influences of nonlinear and coupling relations, research of the asymmetric shape control technology is relatively insufficient. For a long time, it fails to develop effective control strategies and on-line control models. The production process can only rely on manually intervene, which leads to the lack of control accuracy and easy to strip shape quality problems. All of these problems seriously affect the product quality of strip steel. To solve the above problems, taking2250mm roughing mill of hot continuous rolling in a conventional domestic factory as the research object, based on problem of the asymmetric shape control of slab in roughing mill, a set of comprehensive tilting control model of slab camber in roughing mill was established based on a variety of numerical calculation methods. The innovative research results of this dissertation were obtained as follows.(1) The calculation formula of camber of the exit slab was established. By establishing the roll-piece dynamic coupling thermo-mechanical finite element model, from two aspects of material and equipment factors, generation mechanisms of asymmetric shape of the exit slab were analyzed, and verify the accuracy of the calculation formula. These theoretical bases were provided for realizing the comprehensive tilting control model of slab camber.(2) Based on rolling force difference on both sides of tilting model of slab camber was established. By combining with spring equations and finite element method, the main factors causing slab camber include the longitudinal stiffnesses of mill on both sides, incoming wedge and deviation. They were used to calculate the corresponding tilting values. Combined with the calculation formula of camber of the exit slab, the tilting values of roll gap were calculated in each pass. The tilting model of slab camber has a more complete theoretical basis and is an effective adjustment method in each pass of the rough mill.(3) Based on center-line deviation of tilting model of slab camber was established. By measuring the center-line deviation data through the width gauge, camber shape of exit slab was resolved. Then, the thickness difference of slab on both sides was converted by camber shape. And the tilting values of roll gap were calculated by the thickness difference of slab on both sides. The lateral flow factor definition was introduced into the tilting model of slab camber. Combined with the finite element method, the tilting model of slab camber was effectively ensured the suitability for different conditions. The tilting model of slab camber can based on the measured data of camber to achieve effective regulation in the first and even pass of roughing mill.(4) The control strategy was put forward by comprehensive between the two kind of above-mentioned models, based on RBF neutal network forecasting model of a comprehensive tilting control model, and the on-line adaptive model, were established. They were used to optimize the deviation factor of the tilting values of roll gap in each pass, and can continuously improve the setting precision of the tilting model of slab camber by the measured rolling data. A complete camber control system with automatic optimization capabilities was formed. Since putting the model into experiment on roughing mill, the camber values which not meet the standard rate declined from24.88%to6.62%. This shows that the camber model effectively controled the slab camber problem in rough rolling and improved the level of camber control. |
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