System for speed mode control of the electric drives of the continuous train of the hot-rolling mill

It was noted that at the manufacturing thin strip at the wide-strip hot-rolling mill stricter requirements to the gauge deviations (uneven gauge) along the strip length are applied. Using the 2,500 mm mill of OJSC Magnitogorsk Iron and Steel Works (OAO MMK) as an example it has been proved that rolling is performed with tensions which exceed several times the accepted values. The main cause is incoordination of speeds of the continuous train electric drives. The developments carried out aim to improve accuracy of setting and controlling loop height in the inter-stand gap. The paper provides the structural diagram of the system of the cascading correction of the stand electric drive speeds. Its distinctive feature is the transmission of the correction signals against the rolling direction. The paper considers the developed system of the strip loop size control effecting speed adjustment for the previous stand of the interstand gap. It substantiates dependencies for calculation of the setting and correction signals. It provides results of the experimental studies of the dynamic modes at the control and disturbance actions. Based on the long-term operation of the developed system at the 2,500 mm mill, its advantages in comparison with the pervious system have been verified. Technical efficiency involves improving accuracy of supporting the set tension and gauge of the rolled strip.