Method of Improving Response Rate of System of Controlling Electric Drives of Horizontal Roll Stand in «Ski Forming» Mode

Abstract

The paper gives a brief characteristics to the metal rolling technology in a reversing roll stand of a thin-sheet mill. It points to the relevance of reducing the accident risk of the roll stand electromechanical systems and auxiliary mechanisms. By the example of the rolling mill 5000 at the Magnitogorsk Iron and Steel Works, PAO (PAO “MMK”) the author provides a rationale for the need to improve the algorithms of control over interconnected electric drives of the upper and lower rolls in the mode of forming the rolling front end bend in the form of “ski” (“ski forming” mode). The research considers the structure of the system controlling speed rates of electric drives including the “ski forming” system and a load compensator for the compensation of electric drive loads in a quasi-steady rolling mode. Note that the drawbacks of the existing system are long response time and mismatch of the “ski forming” algorithms and load compensation algorithms. The author analyzed the oscillograms of speeds and moments of engines of upper and lower rolls confirming the aforementioned drawbacks. Further, the paper considered the method of improving the response time of the “ski forming” system by means of forming various rates of electric drive speed setting for upper and lower rolls. The system structure and the graphs of speed setting are provided for the explanation of the proposed method. The research presented the results of simulating speed and moment transition processes at project adjustment of the “ski forming” system and at the implementation of the developed method of electric drive control. The author drew the conclusions on reducing the time necessary for the compensation of speeds and mismatch of drive moments in the steady rolling mode. In the course of the research the oscillograms obtained at the algorithm introduction to the APCS of the mill 5000 for the method implementation were considered. The paper proved the improvement of the control indicators and compliance of experimental results with the expected theoretical results. In addition, the author pointed to the technical advantages of the developed method and provided the recommendations for its introduction at the existing hot rolling mills.