Patent ID: 6935408

Claim:
Method for producing steel slabs, where the strand leaving the mold contains molten metal enclosed by a strand shell, and where, in a following strand guide system, the gap width of the guide rolls, which are supported in segments in an upper and a lower frame, can be adjusted continuously in successive steps by adjusting elements which connect the rolls, comprising (a) changing the gap width by oscillation around a centerline of the gap width in such a way that the dynamic influences on the guide rolls are negligibly small; (b) setting the amplitude of the gap width oscillations to a value which does not cause any plastic deformation of the strand shell; (c) detecting the current gap width of the guide rolls; (d) simultaneously determining the actuating force of the adjusting elements and the amplitude of the actuating force; and (e) wherein when the amplitude of the actuating force increases, the gap width is adjusted to a predetermined value and/or is guided as a function of pressure by means of at least one adjusting element, wherein a force/distance diagram of the gap width setting is determined on the basis of a plurality of force/distance measurements along the strand, which diagram is composed of a plurality of small force/distance curves linked like a chain, each in the form of a hysteresis curve, each of which can be determined by means of an oscillation of comparatively small amplitude, and characterized in that whether the adjusted gap width of the guide rolls is deviating from the optimum value in the direction of “too big” or “too small” is determined on the basis of each hysteresis curve after only one oscillation of comparatively small amplitude, whereupon a corresponding correction is made.