Study On Control Of Flatness And Surface Roughness On Cold Strip Rolling Mill

The control of flatness and surface roughness in cold strip rolling is a theory contact practical problem,being the important factors in determining the quality of cold rolled strip flatness and control anneal felt. However the quality of flatness and surface roughness can't complete satisfy the requirements of both the consumers and cold rolling process itself at present. The main reason for this is that there're all kinds of flatness control technology and perfect control system, but lack of the well-developed technology in surface roughness control correspondingly, furthermore it's a contradiction between flatness control and roughness control in cold rolling which are the key process of putting the control technology in practice. the studies on flatness control are in depth. The studies don't only cover the field of modeling flatness by computation module with preset values, but go deep into the field of flatness automation control system, whereas studies on the latter, which include the formation law of strip surface roughness, the changing law of work roll surface roughness and the transferring ratio, are so deficient that they become the bottleneck in the research of flatness and surface roughness control. In strip cold rolling process, the rigorous requirements on flatness and surface roughness are put forward in every case of producing strip by bell annealing after cold rolling, moreover flatness and surface roughness are both controlled by final pass of cold mill. As if there is no way to get congruity between flatness and surface roughness, for the control of the latter, larger rolling force during the final pass is expected, while the former stands against. In fact the phenomena exist in writer's 1727mm plant and have never been solved. On the basis of actual measurement,field trial as well as observation and analysis for a long time, the law of strip flatness and surface roughness formation, the changing law of work roll surface roughness and the transferring ratio have been studied, ultimately the mechanism of contradiction is uncovered and solution is applied to industrial manufacture. In conclusion several creative achievements have been obtained as follows in this paper:1. A reasonable solution to settle flatness and surface roughness problem is raised, which includes using a larger rolling force and backup roll with VCL profile.2. Models to predict strip surface roughness or to estimate the transferring ratio are established by means of stepwise regression, finally the model of roll surface roughness...