Metal deforming – With cleaning – descaling – or lubrication of work or product – Lubricating
Patent
1994-05-10
1997-12-09
Larson, Lowell A.
Metal deforming
With cleaning, descaling, or lubrication of work or product
Lubricating
72201, 723652, B21B 2710
Patent
active
056947992
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the hot-rolling of metal strips in one or more rolling passes, wherein the metal strip is cooled on the entry side and on the exit side of a roll stand by spraying a coolant liquid against the metal strip and the rolls in a region extending over the entire width of the metal strip.
In the hot-rolling of metal strips in a rolling mill having one or more roll stands, the work rolls are deformed to such a degree as a result of heating that they can no longer be used to roll flat strips. To prevent such deformation, it is known from DE-C2 26 52 845 to cool the work rolls by spraying coolant liquid directly on their outer surface. This spraying is effected primarily on the exit side of the roll stands and wipers are applied to the work rolls, particularly on the entry side of the stands in the event that this side is also to be sprayed with the coolant liquid, which wipers prevent the coolant liquid from coming into contact with the hot metal strip being fed in.
Further, it is known to cool the work rolls both on the entry side and exit side of the roll stands by spraying coolant liquid exclusively and directly on the outer surface of the work rolls (EP-B1 0 191 199). In this case, there are no wipers arranged at the work rolls on the entry side, so that the coolant liquid can penetrate into the roll gap due to the rotation of the rolls and can accordingly come into contact with the entering metal strip so as to be distributed unevenly along its width prior to the roll gap. Since the cooling of the strip along its width is not controlled or regulated and is accordingly not uniform, this leads to the formation of undesirable stripes (so-called cooling stripes) on the upper surfaces of the metal strip. For reasons of quality, these stripes are to be prevented at all events. Although it has been shown in practice that it is possible to oppose deformation of the work rolls by cooling them in this way, surface defects in the form of circumferential flaking (removal of material) still occur at the surfaces of the work rolls even when this method is applied. As with the formation of stripes, this flaking is disadvantageous for the surface quality of the metal strips to be rolled. Finally, it is also known to apply coolant liquid not only to the outer surface of the work rolls, but also to the strip EP-B10 138 503). However, this prior art does not show in particular how the metal strip and the surfaces of the work rolls, in particular on the entry side, are acted upon by the coolant liquid at the same time. In the embodiment example, spray nozzles are associated with the work rolls only on the exit side of the roll stand.
SUMMARY OF THE INVENTION
2. Description of the Related Art
Further, a process for hot-rolling of metal strips in one or more passes is disclosed to the person skilled in the art in SU-A 1 227 275, in which the metal strip is cooled on the entry side and on the exit side of the roll stand or roll stands together with the work rolls by spraying a coolant liquid in a region extending over the entire width of the metal strip. The spraying of a coolant liquid on the entry side is affected in such a way that the surfaces of the rolls directly in front of the roll are cooled to a temperature below the boiling point of the coolant liquid. At each work roll, on the side on which the strip enters the roll gap, there are three spraying zones in arrangements distinct from one another and accordingly three cooling zones which are separate from one another, each of these spraying zones having a distinct function to carry out. This requires complicated plant technique, since a separation of cooling zones can only be achieved by means of complicated mechanical parts. Further, the control technology is extremely complicated for individual spraying zones having different cooling functions. Finally, intensive cooling of the surface of the rolling stock prior to deformation in the roll gap is disadvantageous due to the risk of unc
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Heymann Friedrich
Mohlenkamp Manfred
Pietzko Gunter
Wolpert Waldemar
Kueffner Friedrich
Larson Lowell A.
Schoeffler Thomas C.
SMS Schloemann--Siemag Aktiengesellschaft
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