Planarity control in the rolling of flat stock

In a control circuit for maintaining planarity of flat rolled stock as rolled in a rolling stand said rolling stand exerting a particular bending force upon the stock being rolled, the control circuit including equipment for measuring planarity of the stock being rolled, means for providing desired values of planarity, and means connected to said equipment and means, for controlling a rolling process in dependence upon deviation between a desired value of planarity and an actual value of planarity and including particularly means for controlling parameters of and in the rolling stand to obtain the requisite correction, the improvement comprising:

• a control circuit including a bending force reference signal source;
• means (i) connected to the rolling stand for ascertaining the actually effective rolling force as exerted upon said rolled stock in said rolling stand and for ascertaining variations of said force;
• means (ii) connected to the means for ascertaining, and providing (a) a signal representing particular corrective characteristics and providing (b) a rolling process corrective output in response to said signal;
• and
• means connected to the means (ii) and to the control circuit for introducing said corrective value as a modifier of the bending force reference signals in the control circuit, for modifying the ascertained difference between desired and actual values of planarity said modifier being effective as an anticipatory control action, anticipating ascertainment of planarity deviations before they actually occur thereby tending and on an empirical statistical average basis, to thereby remove causes for lack of planarity before they occur and are ascertained.