GB1141584A - Improvements in or relating to continuous hot rolling mills - Google Patents

Abstract

1,141,584. Automatic control of rolling. GOSUDARSTVENNY PROEKTNY INSTITUT TYAZHRPOMELEK-TROPROEKT. June 6, 1967, No. 26040/ 67. Heading G3R. The pressure between the rolls of the last stand of a multi-stand strip metal rolling mill is maintained constant by automatic control of roll speed at the last stand tension in the metal prior to its passage through the last stand being maintained between limits by automatically controlling screwdown at an earlier stand at intervals, and the gain of the roll speed control system being automatically reduced when tension approaches either limit. As shown, a signal derived from a pressure transducer 7 associated with rolls 3, 4 of the final stand 1 of a continuous hot strip rolling mill is compared with a reference signal from a source 8 and any error is eliminated by applying the difference to adjust a speed controller 9 for a roll driving motor 5. This varies the tension in the strip between stands 1 and 6 and deviations beyond predetermined limits are detected by a tension transducer 10 which restores tension between the limits by operating a screwdown motor 12 associated with stand 6 at intervals sufficient to allow passage of the strip from stand 6 to stand 1 between adjustments. When tension approaches either limit, the signal from tension transducer 10 also reduces the gain of speed controller 9, to zero at the limit, until tension is restored between limits again, thereby avoiding excessive variations of speed.