Phase compensator for gauge control using estimate of roll eccentricity

摘要

A method of controlling a rolling mill at high exit strip speed in which eccentricity of one or more of the roll assemblies causes undesired variations in the gauge of material exiting the mill. The method includes storing a model of the response of the load cells that measure the force at which the rolls of the mill engage the material in the mill, and a model of the response of actuator mechanisms of the mill that provide the force. In addition, the frequency of any eccentricity of one or more of the rolls during rotation. This frequency and the stored models are utilized to provide an estimate of possible phase errors caused by the lag in the response of the load cells in measuring the occurrence of cyclic changes in force due to eccentricity of the rolls and by the lag in the response of the actuator mechanism in moving to a particular position upon command from a controller. The estimated phase error is then used to calculate a set of phase compensator gains that operate on the frequency domain representation of the eccentricity estimate in such a manner that when it is transformed to a command signal that is applied to the actuator mechanisms they change position to offset the effects of roll eccentricity on the gauge of the product exiting the mill.