Adaptive Load Division Controller for Electric Drives of Roll Stand

A model 5000 plate rolling mill was used to analyze the causes of load mismatch in individual electric drives of upper and lower rolls of the horizontal stand. The main cause was identified as the low response rate of the load division controller (LDC) that is switched on after the ski formation is complete. As a result, the motor moments differ by 2 times or more, which causes the increased temperature in the motor that has a greater load and an increased risk of accidents. The authors present the analysis of oscillograms showing that during the first passes of the roughing stage, the electric drive with the greater load reaches the moment limit and thus enters the uncontrolled mode. To overcome the said drawbacks, an electric drive control method was developed that includes forced alignment of roll motor speeds by eliminating the integral component and the amplification of the proportional component of the LDC output signal. The authors developed an adaptive LDC to implement this method. The research involved simulation modeling and experimentation of a rolling mill. The results confirmed that the load alignment periods for upper and lower roll motors were reduced by at least 2 times. The developed LDC was commissioned for pilot commercial operation on a model 5000 rolling mill, and recommendations were made to expand its usage.