Method and Casting/Rolling Plant for the Production of Hot-Rolled Metallic Strips, Especially Steel Strips, Having Great Surface Quality

Abstract

Disclosed are a method and a casting/rolling plant for producing hot-rolled metallic, particularly steel, strips ( 7 ) having great surface quality from slabs or flat thin bars ( 2, 2 a ) that are cast in a continuous casting process, descaling being performed based on a rotary descaling process. In order to take into account parameters which are not considered in prior art in addition to rotary descaling, the hydraulically oscillated permanent mold ( 9 ) travels along several different oscillation curves ( 16, 17, 18 ) while the oscillation marks are deep-cleaned by adjusting the oscillation pattern that is determined to be optimal for each casting material.

1 . A method for producing hot-rolled metal strip, especially steel strip ( 7 ), of high surface quality from continuously cast slabs or thin slabs ( 2 ,  2   a ) cast with the aid of a hydraulically oscillating continuous casting mold ( 9 ), which is subjected to a descaling of the strand surface ( 2   c ), heated to rolling temperature, and finish rolled to thin strip gauges in a multiple-stand hot-strip rolling train ( 6 ), where the cast strand ( 2   a ), after emerging from a strand guide ( 3 ), before entering a soaking furnace ( 4 ) and/or after emerging from a soaking furnace ( 4 ) and entering the hot-strip rolling train ( 6 ), is sprayed on one or both of its surfaces ( 2   c ) by several rotating nozzles ( 15 ), from which pressurized liquid ( 19 ) is recurrently sprayed onto the same places on the surface with high impact pressure to remove scale and/or casting flux and to deep-clean the oscillation marks, wherein the hydraulically oscillated continuous casting mold ( 9 ) is moved in several different oscillation curves ( 16 ,  17 ,  18 ), where the oscillation curves ( 16 ,  17 ,  18 ) are obtained by different magnitudes of mold oscillation, different casting speeds, different advancing mold speeds during the downward stroke, and different curve forms, and where the deep cleaning of the oscillation marks is carried out by setting the oscillation pattern ( 16   a,    17   a,    18   a ) determined for each casting material. 
     
     
         2 . A method in accordance with  claim 1 , wherein much less pressurized liquid ( 19 ) is admitted into the rotating nozzles ( 15 ) as pressure medium than has previously been used in so-called descaling sprayers, with parameters of the casting or rolling process that are otherwise the same. 
     
     
         3 . A method in accordance with  claim 1 , wherein the temperature losses of the cast strand ( 2   b ) are kept low by admission of pressure medium to the rotating nozzles ( 15 ) under automatic control according to the temperature level of the cast strand or strand of rolling stock ( 2   b ). 
     
     
         4 . A casting and rolling plant ( 1 ), especially a compact casting and rolling plant (CSP), which consists of a continuous casting installation ( 2 ) for liquid metals, especially liquid steel, whose continuous casting mold ( 9 ) is connected with a hydraulic oscillation drive ( 9   a ), which is followed in the direction of strand withdrawal ( 11 ) by at least a strand guide ( 3 ), a soaking furnace ( 4 ), possibly a furnace transverse conveyor ( 5 ), a multiple-stand hot-strip finishing train ( 6 ), and a coiler ( 8 ), wherein a device ( 14 ) with rotating nozzles ( 15 ) is arranged between the strand guide ( 3 ) and the soaking furnace ( 4 ) or between a straightening driver ( 12 ) and a shear ( 13 ) and/or between the soaking furnace ( 4 ) and the hot-strip finishing train ( 6 ), before the first rolls, and where a pressure medium is recurrently sprayed from these nozzles ( 15 ) onto the same places on the surface with high impact pressure. 
     
     
         5 . A casting and rolling plant in accordance with  claim 4 , wherein several nozzles ( 15 ) for pressure medium are installed on a rotor ( 20 ). 
     
     
         6 . A casting and rolling plant in accordance with  claim 4 , wherein several rotors ( 20 ) with nozzles ( 15 ) for pressure medium mounted on the periphery ( 20   a ) of the rotor are arranged in a row transverse to the direction of travel of the cast strand or strand of rolling stock ( 2   b ). 
     
     
         7 . A casting and rolling plant in accordance with  claim 4 , comprising the use of the rotary descaling device in a hot-strip rolling train ( 6 ) with seven or more finish rolling stands ( 6   a ) before entry into the first finish rolling stand ( 6   a ).