With hot rolling of steel strip, hard surface oxide and/or scale layer forms which adheres rigidly to the metal surface of the strip.
Prior to the softening working processes for such steel strip, particularly in a cold rolling process, the scale layer should be removed to avoid a rolling of scale into the steel strip and the formation of surface deformaties or imperfections.
Ordinarily the scale layer is removed in a corrosive chemical bath. Usual scale thicknesses require long reaction and residence times so that an undesirably large size for the bath is necessary and both maintaining the desired bath concentration and later disposal of the bath fluid make for considerable difficulty.
A mechanical descaling by grinding or milling according to German Patent No. 886 585 does not take into consideration the profile of the steel strip so that metal from the middle of the steel strip is removed while scale may remain on the edge regions of the steel strip.
The exposure of the surface of the steel strip to abrasive particles and a waste water mixture has not proved effective so that also undesirably large lengths for the scale removal path were necessary and additionally the danger of damage to the strip surface existed (German Patent No. 28 31 229).
In an attempt to try to find a problemfree descaling for steel, a process has been set forth in German Printed Patent Application DE-AS No. 12 48 600 according to which the steel strip coming along the roll path runs through a reducing rolling mill under operation of a strong pulling force. To be able to apply the desired strong pulling force suitable roll arrangements causing the pulling force can be arranged before or after the rolling mill; nevertheless the effect is unsatisfactory.
According to the Soviet Patent document No. 560 657 an increased effectiveness for removal of scale should be attained when the reduction is performed under simultaneous bending and sliding according to the slidable roll process. The strip is slung about half way around the working rolls on entering and/or exiting; this has proven to be disadvantageous and a consideration of the strip profile is practically not possible so that with customary profiles the fitting of the roll gap is only limitedly possible at best.