Beschreibung:
The use of lubrication during hot rolling presents a lot of advantages. One of the main advantages is the considerably high reduction of rolling force, which leads besides the energy saving (up to 15%) to a reduction of roll wear (longer rolling campaigns and roll lifetime). Product surface quality is greatly improved by a decrease of shearing forces in the roll gap and it can also be used for the reduction of the final thickness of hot strips of different steel grades. In recent years, most hot mills have been equipped with lubrication systems, all based on water-lubricant unstable emulsion application. The drawbacks of actual emulsion systems, mainly uncontrollable oil-water mixing, pipe stops due to water in oil emulsion, influence of the specific flow rate, and distortion by skin cooling, instigated the search for a new method of lubrication. A new lubrication technology adapted by CRM based on the atomising of pure (natural) oil in very low quantities (0.4 g/m2) and good homogeneity has been tested in stand F2 of the hot strip mill in ArcelorMittal Dunkerque. Its implementation is the result of close cooperation between CRM, TKS, ArcelorMittal R&D (ARSA) and ArcelorMittal Dunkerque. The main benefit of pure (natural) oil atomising is increased efficiency: 40 to 50 % higher efficiency compared to emulsions (with additives). With this technology it is possible to use low polluting (natural) oils and to regulate directly the oil flow rate on top and/or bottom roll, without negative effect when skin cooling is switched on.