Study On Thermal Behavior Of Rollers & The Compensation Methord In Cold Rolling

The thermal behavior of rollers is one of the main interferences in rolling process, especially for the thermal expansion, the thermal camber and their change process. In the market competition, the quality of production is the key to win for all steel enterprises. For the cold rolling strip, the thickness precision and the shape of strip is the most important dimension precision target, and a severity challenge must face to is how to improve this dimension precision. During modern cold rolling process, the rolling speed and the power is rather high, and a part of power is transferred to heat conducting to the rollers, the strip, and environment. The dynamical heat exchange results in the thermal expansion and camber, and influence the thickness precision and the shape of strip. The new sally port to improve rolling quality is that study on the thermal behavior of rollers, and compensate it according the prediction in the AGC and AFC. This dissertation takes the temperature field and thermal behavior of working rollers and as the research objects, focuses on the solutions to key technologies, and put the research result to compensate thermal behavior in 300 strip cold rolling control system. The main work is as follows:Firstly, basing on the conventional model of temperature field and thermal behavior, a new building model method called "scanning method" is advocated, which derivates the quasi three dimensional temperature field from a sequence two-dimensional temperature field. Although the research object is a longitudinal section actually, the continuation of this section can form the whole roller temperature. During the analysis, all the three dimensional conducting is take in calculation. This new method can descript the feature of temperature field on detail, and reduce the computing work at the most. This is very rational for thermal behavior of roll.Secondly, basing on the reasonable analysis of the theory of AGC andAFC, the relation of the thermal behavior, the thickness of strip, the stiffness of roll mills, and other variables in process is find out. According the data mining theory and the error tracing technology, and basing on the data of 650 reversible cold strip roll mill, a new method is putting forward to discover the valuable rule hiding behind mass process datum, including the thermal behavior of working rollers. Thirdly, the rolling experiment is proceeds on 300 reversible cold strip roll mill. During experiment, all the process data are saved in a process database, according to which the thermal behavior of rollers in the rolling process is tracing out. It provides the directly evidence to testify and optimize the digital model and predication model. And the thermal image of rollers is collect and record on period, as a reliable evidence for digital model. Basing on the experiment and fusing all the field data, some model parameter is optimized with a genetic algorithm program. The optimized model is more accurate and more reliable.Finally, According the predication of the thermal expansion, the thermal camber, the control system adjusts the set value of press down displacement and the bending roller force to compensate influence of thermal behavior of rollers. The rolling results show that this model is accuracy, and the longitudinal thickness error is lowed significantly, the cross difference of thickness error is more stable, and the shape of strip is rather good.