Method and device for cooling a leader or band of a metal strand in a hot-rolling mill

Abstract

A method and device for cooling a preliminary strip of metal in a hot rolling mill including work rolls by spraying a cooling agent on to the preliminary strip, screening the preliminary strip in an edge area of the strip from influence of the cooling agent, and deflecting the cooling agent in the area of the strip edges of the preliminary strip, wherein the cooling agent is deflected from the strip edges in an area of an inlet guide of a work a work roll.

Claims

1. A method for cooling a preliminary strip or strip of a metal strand in a hot rolling mill including work rolls, comprising the steps of: spraying a cooling agent onto the preliminary strip or strip as the strip moves in a travel direction; screening the preliminary strip or strip in an area of edges of the strip from influence by the cooling agent; guiding the strip with lateral guides; and, simultaneously deflecting the cooling agent in the area of the strip edges of the preliminary strip or the strip with downwardly inclined plates mounted only on a downstream end, relative to the travel direction, of the lateral guides so that the cooling agent is deflected from the strip edges immediately in front of a roll gap between the work rolls in an area of the lateral guide, wherein the inclined plates and the lateral guides are moved together transversely to a travel direction of the strip to adjust positioning of the inclined plates and the lateral guides.

2. The method according to claim 1, including deflecting the cooling agent in the area of the strip edges to areas outside of the preliminary strip or the strip.

3. A hot rolling mill, comprising: a preliminary train and a finishing train for rolling a preliminary strip or a strip of a metal strand with work rolls; lateral guides for guiding the preliminary strip or strip, the lateral guides being arranged in front of an inlet gap formed by two work rolls; a cooling device for applying a cooling agent to the preliminary strip or the strip as the strip moves in a travel direction; and means for screening the strip edges of the preliminary strip or strip from the influence of the cooling agent immediately in front of a roll gap between the work rolls, wherein the screening means includes downwardly inclined plates mounted only on a downstream end, relative to the travel direction, of the lateral guides, wherein the screening means are moveable together with the lateral guides transversely of a travel direction of the preliminary strip or the strip.

4. The rolling mill according to claim 3, wherein the screening means are separate structural elements.

5. The rolling mill according to claim 3, wherein the means deflect the cooling agent outwardly away from the preliminary strip or the strip.

6. The rolling mill according to claim 3, and further comprising a loop lifter, wherein the screening means are arranged on a bottom side of the preliminary strip or the strip in an area following a loop lifter.

7. The rolling mill according to claim 3, further comprising further means for screening the strip edges in an area of an intermediate stand cooling.

8. The rolling mill according to claim 7, wherein the further means for screening the strip edges is arranged in a cooling device in areas between a preliminary stand and a first finishing stand.

9. The rolling mill according to claim 7, wherein the further screening means includes a screening width adjustment device.

10. The rolling mill according to claim 9, wherein the screening width is adjustable differently for various devices.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the drawings:

(2) FIG. 1 is a graph plotting temperature of a metal strip as a function of strip width,

(3) FIG. 2a shows a sectional view of a metal strip traveling through a roll stand in the area between two cooling beams transversely of the travel direction with lateral guides and devices in the side areas of the metal strip for screening the cooling agent from the edge areas of the metal strip in front of the inlet gap of two work rolls,

(4) FIG. 2b is a top view of the metal strip according to a line II-II of FIG. 2a and additionally a screening device for screening cooling agent which is arranged in front of the inlet lateral guides, and

(5) FIG. 3 shows a sectional view of the metal strip and a lateral guide in accordance with line III-III of FIG. 2a, as well as additionally the cross sectional view of the screening device arranged in front of the lateral guide.

DETAILED DESCRIPTION OF THE INVENTION

(6) In a rolling mill including a plurality of roll stands, a preliminary strip and a strip 4 (FIGS. 2a, 3) of a metal strand to be rolled run through the roll gaps 5 between always two work rolls 6, 7. In the areas in front of the work rolls 6, 7 lateral guides 8, 9 are mounted at the side edges of the strip 4, wherein the guides 8, 9 are constructed approximately U-shaped in cross section and engage over the strip 4 on the top side and the bottom side in the edge areas thereof.

(7) On the upper and lower sides of the strip 4, cooling devices are provided as cooling beams 10, 11 from whose nozzles 12 is sprayed a cooling agent, particularly water, under pressure onto the surface of the strip 4 in order to cool the strip. The nozzles 12 produce on the surface of the strip 4 impingement areas 13 of the cooling agent. According to the invention, screening devices 14, 15 are provided which prevent the cooling medium from being sprayed directly onto edge regions of the strip 4 from the nozzles 12 in the edge areas of the strip 4. The screening devices 14, 15 deflect the cooling agent jet always preferably in the area laterally of the strip 4.

(8) In particular the upper screening device 14 therefore includes on both sides of the strip 4 downwardly inclined plates 16 and 17, inclined toward the outer side of the strip 4. On the bottom side of the strip 4, plates 18, 19 of the screening device 15 can also extend horizontally relative to the plane formed by the strip 4 because the cooling agent is already deflected downwardly as a result of the force of gravity.

(9) Preferably, the screening devices 14, 15 or 16, 18 can be attached to the guides 8, 9 as separate components, or the screening devices 14, 15 or 16, 18 are fixed components of the guides 8, 9. If the guides 8, 9 are displaceable in accordance with the width of the strip 4 to be rolled transversely of the travel direction of the strip 4 in the direction of double arrows A, B, the screening devices 14, 15 or 16, 18 are displaced in the same manner. It can also be provided that the plates 18, 19 are pivotable or inclined in order to adjust the impingement area of the screened cooling agent jets.

(10) In addition to the arrangement of the screening devices 14, 15 or 16, 18 in the areas in front of the roll gaps 5 between work rolls 6, 7, a screening device 20 can also be arranged in front of the lateral guides 8, 9 on the bottom side of the strip 4; this is additionally illustrated in FIGS. 2b, 3. The screening device 20 is in principle constructed as the screening devices 14, 15 or 16, 18 and comprises in the same manner the plates 21 for deflecting the cooling agent which flows from the nozzles 22 of a cooling beam 23.

(11) It is understood that the invention can be used independently of the fact whether the cooling agent flows from individual nozzles or is injected in form of a curtain on the strip 4 which has a rectangular nozzle opening extending over the width of the strip 4. In addition to water it is also possible to use as cooling agent other media, such as liquid nitrogen or water/air mixtures.

(12) The device for screening the edges of the strip 4 described in connection with the Figures can also be utilized within the finishing train at various locations, particularly also in a preliminary strip cooling or an intermediate stand cooling. In this connection, separate adjusting mechanisms can be used for moving and adjusting the screening elements to the strip width.