Study On Axial Shifting Positions Of CVC Work Rolls In Hot Strip Rolling

The shape of steel strip is one of the most important indicators to measure the quality of steel strip,so shape control technology of steel strip has always been one of the core technologies of strip rolling,and also the hot spot of current researching in the field of strip rolling.Wear and tear of working rolls can directly affect the surface quality and shape of steel strip in rolling process.During the practical production,the work roll often suffers severe uneven wear where it is in contact with the edge of steel strip,resulting in a partial of high point for the steel strip.This paper took the project "Develop the double closed loop program about micro medium wave rolling and air cooling temperature in laminar air cooling time on the basis of SIEMENS two level model" as the background that was pushed ahead by Northeastern University and Chenggang.Strip shape control system of SIEMENS and the problem about severe uneven wear of work rolls for Chenggang were studied,the main contents are shown as follows:(1)The strip shape control system of SIEMENS used in Chenggang 1780mm hot strip rolling line was digested and absorbed.The structure of system for hot-rolled steel strip shape control,the control strategy of strip shape for hot strip rolling and the pre-setting module,the dynamic control module,the adaptive module in SIEMENS strip shape control system were studied.Functions about calculation modules of elastic deformation of rolls,thermal crown of work rolls and wear crown of work rolls in strip shape control system were discussed.(2)The phenomenon that centralized shifting positions led to severe uneven wear of work rolls and resulted in a partial of high point for steel strip when a lot of steel strips of the same specifications were rolled continuously was analyzed.And the method of avoiding uneven wear of working rolls was put forward.(3)One period of data of PDA and logs for Chenggang was analyzed.Steel strip specifications,shifting positions and bending force of each frame for each rolled strip in this rolling period were analyzed.The feasibility of avoiding uneven wear of work rolls by moving work rolls forward to dispersing shifting positions under the premise of ensuring the flatness and the profile of the strip was expounded.(4)According to characteristic parameters of the CVC curve provided by Chenggang,the relationship between crown of the edge of roll gap and work roll shifting position was deduced;Considering the width of strip,the relationship between crown of roll gap at the edge of strip and work roll shifting position was determined.(5)Three kinds of different specifications of steel strip were selected as research subjects,considering different wear crown and thermal crown of work rolls,limited positions of CVC work rolls moving forward were calculated for each strip by program of calculating the elastic deformation of rolls so that CVC work rolls shifting positions can be dispersed and uneven wear of CVC can be avoided.