METHOD AND EQUIPMENT FOR SECONDARY DESCALING OF METALLIC STRIPS BY HYDRAULIC LOW-PRESSURE SPRAYING OF WATER

摘要

This process for the secondary descaling of running metal strips, especially made of steel, while being hot-rolled, by spraying water onto their surface using spray rails having nozzles supplied with pressurized water, is characterized in that the nozzles are supplied at low hydraulic pressure, not exceeding 30 bar (preferably below 10 bar, but without going below 4 bar), and in that, for the purpose of providing a thermal effect of the water sprayed onto the surface to be descaled quantitatively similar to the thermal effect obtained with the usual known method of secondary descaling at high pressure, namely a cooling of the strip which reduces its surface temperature to around 600°C, said nozzles are adjusted in order that the heat flux density extracted from the strip (HF) resulting from the cooling of its surface by the sprayed water is similar to that produced with said known high-pressure practice. The invention applies to any secondary descaling, both upstream of the finisher and upstream of the roughing device of a rolling mill train. It provides an immediate operational response to the reduction of the descaling costs, that is to say compatible with a restructuring of existing industrial equipment, therefore without necessarily involving the reinstallation of complete new equipment.