Por: luciano alves novelli (gerdau), Aline de Cássia Araújo (gerdau), Fábio Henrique Pacheco (gerdau), Ismael de Souza Dias (gerdau), Willy Schuwarten Junior (gerdau)
Resumo:
The present study was developed in the Hot Strip Mill area that has a Steckel Mill in use. This equipment is a four high reversible stand that has four rolls that are assembled one on the other in the horizontal. The center rolls are known as work rolls, and these are of smaller diameter. There are two other rolls, known as backup rolls, which are of larger diameter. The work rolls that were analyzed in this study have 900 mm of diameter of the work table and weigh 18 tons. They are used in the hot rolling process and are responsible for the reduction of the cross section of the steel plates that arrive in the mill at temperatures around 1250ºC, transforming the steel plates into steel coils. Due to the direct contact of the heated plate with the work rolls, the same are heated and cooled during the process. After the rolling process and the finished campaign, they are with temperatures on the work table around 60ºC. In order to be regrinding and return the quality conditions of the surface, the rolls must be at temperatures of up to 30ºC. Thus, a system of cooling the rolls was provided, consisting of two pipes with holes that can project water on the surface of the rolls. About 90 minutes of forced cooling is required to meet this parameter. The creation of a new rolls cooling system composed of two piping arrangements with heat extraction nozzles was focused by this development. Some data was collected on the cooling time of the rolls, as well as temperature measurements from all the rolls. The new system was able to reduce the forced cooling time satisfactorily, which impacted the total cycle time of the roll and had greater availability of this input. We also had a very significant environmental impact because, due to the shorter time, we consumed a smaller volume of water.
