Method for the controlled pre-rolling of thin slabs leaving a continuous casting plant, and relative device

Method for the controlled pre-rolling of thin slabs leaving a continuous casting plant, comprising pre-rolling a thin slab with a plurality of pairs of rolls grouped together in one or more pre-rolling assemblies, the first of the pre-rolling assemblies being positioned immediately downstream of foot rolls of a mold, at least one displaceable roll being included in the pairs of rolls, the pairs of rolls being associated with pressure transducer means and hydraulic capsule means, position transducer means being included, the pressure transducer means and position transducer means being associated with a data processing unit, at least the first of the pairs of rolls processing a slab which has just emerged from the mold with a thin solidified skin;

• monitoring the temperature of a liquid bath in a tundish;
• monitoring the casting speed;
• monitoring the temperature of the slab while the slab is leaving the mold and while the slab is within the pre-rolling assembly;
• sending signals concerning the temperature of the liquid bath in the tundish, the casting speed, the temperature of the slab while the slab is leaving the mold and while the slab is within the pre-rolling assembly to the data processing unit;
• and controlling, on the basis of a governing and control program, the reciprocal positions of the rolls of at least a part of the pairs of rolls so as to achieve a pre-rolling with a reduction of the thickness of the slab leaving the last pair of pre-rolling rolls by at least 10% so as to eliminate the liquid pool and to bring into contact the zones in a two-phase condition in order that the central solidification structure be refined and the central segregation and porosity be minimized.