Unwind/rewind eccentricity control for rolling mills

摘要

A method of rolling material in a rolling mill in which the material is directed from an unwind coil of the material to the mill and/or to a rewind coil of the material from the mill, the material being under tension as it is directed to and from the mill. The directing process has at least one cyclic disturbance which ordinarily causes cyclic changes in the tension of the material and in the thickness of the material exiting the mill. The method includes measuring changes in tension and/or thickness, and providing time domain samples of such changes during revolutions of the unwind or rewind coil. The samples are then processed by characterizing them as frequency, magnitude and phase-angle components of the changes using a function that transforms the time domain of the samples into the frequency domain. These components are then emloyed in an update algorithm to provide a current estimate of the cyclic disturbances. The components are then processed by returning them to a time domain value, and using this value to correct for the effects of cyclic change by either controlling the working gap of the mill or the tension of the material in a manner that offsets the occurrence of the cyclic change.