The Research And The Application About Out-of-tolerance Of The Strip Thickness Control Technology In Cold Tandem Rolling Line

High speed ensure the mill increase production and achieve the goal of production capacity. It is the the primary goal of the cold strip mill that every factory want to pursuit.But high speed is the first "killer" during steady operation of Mill.The breakage of strip not only results in the accumulation of strip in mill,but also results in mechanical and electrical equipment damage.A cold tandem rolling line in BaoSteel Corporation selects hot coils from the numerous hot rolling production lines, such as from hot coils produced by Baosteel hot mill line,hot coils produced by Nippon hot mill line and hot coils produced by other hot mill lines in China。Sometimes out-of-tolerance phenomenon of the strip thickness occurs, defines in this as out-of-tolerance defect of the strip thickness, This defect is big hidden danger to line steady operation, Since this line began to produce, it happened strip breakage and a pile of steel in mill stand by out of tolerance defect capture of strip thickness,caused line long time stop and equipment fault,made the heavy losses for this line。In order to reduce the losses to the greatest degree caused by out-of-tolerance defect of the strip thickness, this article take on the original spot equipment as a foundation, does not increase any equipment, make out-of-tolerance defect of the strip thickness as the object of study, it’s main works as follows:(1)For how to detect the thickness defects,it designed a capture program to detect the thickness defect points with the new PLC R700of Hitachi corp.,the program and identify two categories of effective thickness defects.(2)How to keep track of defects for the thickness form line entry to the mill section of the technical problems, it stored dynamicly the information of defects on the memory in the PLC,in order to save system resources, cleverly combined with the original seam tracking program designed a single defect’s tracking program with PLC, it made the goal of accurately track defects to rolling mill.(3)for which manner is the best for defect points go through the rolling mill,according to the test result of defect point going through mill,it study in-depth of the characteristics of automatic thickness control systems,it designed a suitable manner for thickness defects passing the rolling mill with R700PLC,After the program be used,it is more stable and lower rate of breakage of strip for thickness defects passing the rolling mill, achieved expected results.The in-depth studies of the thickness Point defects passing the rolling mill contributes to the more stable rolling of cold milland a help for the technological transformation of the domestic industry.