EP1018377A2 - Method and device for descaling a surface of a cast strand fed from a continuous casting installation, said surface having oscillation marks - Google Patents

Abstract

Process for descaling the surface of a casting rod comprises elongating the rod (1) between the end of the rod support (10) and before the inlet to the compensating oven (11) or before the inlet to the roll stand (33) in a limited region by a two-stage deflection from the horizontal transporting device in the region of each deflection (4, 5), and intensively cleaning the rod surfaces (2, 3) especially in the deflecting regions (4, 5) using hard water jets (8, 9). An Independent claim is also included for an apparatus for carrying out the descaling process.

Description

The invention relates to a method for descaling, in particular oscillation marks having surfaces of a producible in the continuous casting process Cast strand, especially of thin slabs, in a subsequent Hot strip mill with leveling furnace and preferably with several rolling stands be reduced in thickness. Furthermore, the invention relates to a device for Implementation of the method according to the invention.

In the surface cleaning of cast strands cast in continuous casting, in particular of thin slabs, experience has shown difficulties in that the surfaces of the cast strands have transverse irregularities, have so-called oscillation marks, which are caused by the mold oscillation are caused.

These difficulties are exacerbated by the fact that the oscillation marks are not constant in continuous casting operation, but different and in particular fail with different depths of the oscillation marks.

In the technical perfection of the continuous casting technology was in the course of Special attention was paid to the design and function of the mold and constantly developing it as the core of the strip casting technology. Parallel For this purpose, improved casting powder for high casting speeds was used as a lubricant tested and used.

By using a high-frequency oscillation system in connection with optimized Mold geometry was achieved that the surface quality of the cast products could be continuously improved.

Despite this significant improvement in surface quality, In the case of thin slabs in particular, there remains a need for the cast product of Contamination from scale, dirt particles and adhering foreign particles to clean thoroughly, in particular rolling into the surface of the To prevent cast product from rolling out in the rolling stands. Doing so such impurities, especially due to the presence of oscillation marks removed, which is all the more difficult if this is in cross section have an angular or pointed edging.

The invention is based on the object of specifying a method and a device, through which the difficulty in cleaning the surfaces of Continuous casting products, especially for thin slabs, and there particularly and be overcome in the oscillation marks. One is also said to be undesirable strong cooling effect in the cast product using the smallest possible quantities can be prevented by pressurized water.

• daß der Gußstrang zwischen dem Ende der Strangstützung und vor dem Einlauf in den Ausgleichsofen oder vor dem Einlauf in die Walzgerüste in einem begrenzten Bereich durch wenigstens zweifaches Auslenken aus seiner horizontalen Transportrichtung im Bereich jeder Auslenkung einer Dehnung seiner Oberflächen unterworfen wird, und
• daß die Strangoberflächen insbesondere in den Auslenkungsbereichen mittels harter Wasserstrahlen einer intensiven Abreinigung unterzogen werden.

To achieve the object, the invention proposes in a method of the type mentioned in the preamble of claim 1,

• that the cast strand between the end of the strand support and before the entry into the equalizing furnace or before the entry into the rolling stands is subjected to a stretch of its surfaces in a limited area by deflecting it at least twice from its horizontal transport direction in the area of each deflection, and
• that the strand surfaces are subjected to intensive cleaning, in particular in the deflection areas, by means of hard water jets.

Areas arise with the strand deformation provided according to the invention tensile stresses, with the oscillation marks opening a little wider and the hard water jets are more effective, which makes it more intense Cleaning effect achieved down to the bottom of the oscillation marks becomes.

One embodiment of the invention provides that the cast strand is sinusoidal for this purpose or is deflected approximately sinusoidally.

Such a sinusoidal or approximately sinusoidal deflection is guaranteed an almost uniform swelling and decay of the surface tension, thereby avoiding damage to the cast structure.

A further embodiment of the method provides that the extent of each distraction of the cast strand in accordance with the maximum permissible reversible Deformation of the cast strand is made.

Another embodiment of the method according to the invention provides that Extent of each deflection of the cast strand in accordance with the maximum permissible Surface tension of the strand is made.

And finally, a further embodiment of the process provides that the Extent of each deflection of the cast strand in accordance with the material temperature of the cast strand is carried out under constant temperature control.

The aforementioned measures according to the inventive method for compliance allowable deformation or maximum allowable surface tension or the material temperature of the cast strand provide a guarantee for maximum deflection of the cast strand while preventing damage of the structure in the cast strand.

The method according to the invention further provides that the distance between the spray nozzles and the water-irradiated surface of the cast strand is continuously measured and kept constant. So that the working parameters largely constant when using the hard cleaning jets of water held.

For this purpose it is also provided that the pressure of the spray water continuously checked and kept at a high pressure level.

An advantageous embodiment of the method further provides that the cast strand with a number each running in parallel planes and in series arranged water jets is applied, the planes at an angle one of the planes perpendicular to the direction of transport of the cast strand lie and the water jets can be aligned obliquely to the surface of the cast strand are.

This way of working gives the advantage that the bottom with the pressurized water jets of the oscillation marks is achieved even better, one being transverse or oblique direction of impact of the water against the strand movement after the Experience is much cheaper than applying it in parallel.

A further improvement in the cleaning effect can also be achieved in this way be that the water jets with the spray nozzles they generate the spray bars can be moved back and forth in the spray plane.

And finally, in a further embodiment of the method, the Measure be made use of that according to the structural condition of the cast strand in accordance with the cooling that takes place with descaling changing deflection force measured continuously and then the amount of water to be added while maintaining the product of the amount of water and water pressure is set constantly.

This also compensates for parameter changes that are occasionally made by the Casting machine can run out, for example, due to a change in the casting speed or the casting temperature.

In a device for descaling, in particular having oscillation marks Surfaces of a cast strand which can be produced by the continuous casting process, in particular of thin slabs, for carrying out the method according to the invention, the cast strand in a subsequent hot strip mill with a compensating furnace and is reduced in thickness with several roll stands, is in the end Strand support and before entering the equalization furnace or before entering the rolling stands between a pair of directional driver rollers on the inlet side and one Pair of exit-side bending driver rollers present a descaling station that at least two spaced apart in the transport direction of the cast strand has opposite deflection bending rollers, which on each opposite side of the Cast strand spray bar with spray nozzles arranged in an inclined plane assigned.

Further advantageous embodiments of the device are in accordance with the subclaims intended.

Figur 1

eine Stranggießanlage mit darin angeordneter Vorrichtung zum Entzundern von Oszillationsmarken aufweisenden Oberflächen einer im Stranggießverfahren herstellbaren Dünnbramme in schematischer Darstellung;

Figur 2

in Seitenansicht und in vergrößertem Maßstab die Entzunderungsstation gemäß Fig. 1,

Figur 3 a

eine Draufsicht auf die Oberfläche einer Dünnbramme mit Oszillationsmarken,

Figur 3 b

das Strangstück gemäß Fig. 3a in Seitenansicht,

Figur 4

In Draufsicht ein Stück einer Dünnbramme mit darüber angeordneten Spritzbalken und Spritzdüsen.

Details, features and advantages of the invention result from the following explanation of an exemplary embodiment schematically illustrated in the drawings. Show it:

Figure 1

a continuous casting plant with a device arranged therein for descaling surfaces having oscillation marks of a thin slab producible in the continuous casting process in a schematic representation;

Figure 2

in a side view and on an enlarged scale, the descaling station according to FIG. 1,

Figure 3 a

a plan view of the surface of a thin slab with oscillation marks,

Figure 3 b

3a in side view,

Figure 4

A top view of a piece of thin slab with spray bars and spray nozzles arranged above it.

The area of a continuous caster shown in FIG. 1 shows the continuous caster 28 with downstream strand support 10 for guiding and supporting the Cast strand 1 in particular a thin slab. The thin slab is behind the continuous caster in a hot strip mill 32 with equalizing furnace 11 and with several rolling stands 33 reduced thickness. Between the equalization furnace 11 and A cropping shear 31 is arranged on the first roll stand 33. At the end of Strand support at the transition of the thin slab 1 in the horizontal transport direction there are four directional driver rollers 12, which the thin slab 1 in Interaction with the exit-side bending driver rollers 13 through the descaling station 14 convey through. Located in this descaling station 14 two mutually opposite deflection bending rollers 15 and 16. They are arranged in the transport direction of the slab at a distance from each other. This one Deflection bending rollers are a spray bar 17 on each opposite side of the slab, 18 associated with spray nozzles 6, 7 arranged in inclined planes, like this can be seen from Figures 3b and 4. The spray bars 17, 18 are, for example. Distance sensors 19, 20 and distance adjusting means 21, 22 are assigned. So that can the distance between the spray nozzles 6 and 7 and the surface 2, 3 of the Thin slab 1 are kept exactly constant.

The deflection bending rollers 15, 16 are controlled actuating cylinders 23, 24 and displacement sensors 25, 26 assigned. The deflection bending rollers 15, 16 can thus either be regulated away or load-controlled adjustable distance. For this you can the actuating cylinders 23, 24 control means for monitoring the deflection 4, 5 or the deflection forces. To protect against external influences the descaling station 14 is covered with a protective box 27.

It can be clearly seen from FIGS. 1 and 2 that the thin slab 1 between the end of the strand support 10 and before entering the equalization furnace 11 in one limited area 29 by at least twice deflecting from it horizontal transport direction in the region of each deflection 4, 5 of an expansion their surfaces 2, 3 is subjected, and that the surfaces 2, 3 in particular in the deflection areas 4, 5 by applying hard water jets 8, 9 are subjected to intensive cleaning.

The deflection bending rollers 15, 16 can be adjusted by means of the corresponding adjusting means 23-26 achieved that the extent of each deflection 4, 5 of the thin slab 1 after Provided their maximum allowable deformation is made.

The extent, here deflection 4, 5, can also be in accordance with the maximum permissible Surface tension can be made.

From Figures 3a, 3b and 4 it can also be seen that the thin slab 1 with a number each running in parallel planes x-x and arranged in series Water jets 8, 9 is applied, the planes x-x at the angle α or β to a plane perpendicular to the direction of transport of the slab y-y lie and the water jets 8, 9 obliquely to the surface 2, 3 of the thin slab 1 can be aligned. By means of the water jets 8, 9 in particular the Oscillation marks 30 cleaned to the bottom.

The water jets 8, 9 can also be sprayed with the spray bar 17, 18 can be moved back and forth in the plane y-y. The water jets 8,9 either according to FIG. 3b or FIG. 4 obliquely against the transport direction 34 the slab 1 be directed. However, they can also be aligned with the transport direction 34 be, the choice of this orientation depending on the prevailing Operating parameters can be set by the specialist from case to case.

Regarding FIG. 4, it should be noted that the water jets 8, 9 drawn as arrows emerge from the underside of the spray bars 17, 18, of course, like this 3b shows, and only for reasons of clarity are shown as if they were on the side facing away from the thin slab 1 the spray bars 17, 18 emerge.

According to the invention, the descaling device with the claims Features (Fig. 2) also before the entry of the thin slab in the roll stands 33 are provided.

Reference list

1

Cast strand, thin slab

2nd

surface

3rd

surface

4th

Deflection

5

Deflection

6

Spray nozzle

7

Spray nozzle

8th

Water jet

9

Water jet

10th

Strand support

11

Compensating furnace

12th

Directional Driver Roles

13

Bending driver rollers

14

Descaling station

15

Deflection bending roller

16

Deflection bending roller

17th

Spray bars

18th

Spray bars

19th

Distance sensor

20th

Distance sensor

21

Positioning means

22

Positioning means

23

Actuating cylinder

24th

Actuating cylinder

25th

Displacement sensor

26

Displacement sensor

27

Protective box

28

Continuous casting machine

29

Deflection range

30th

Oscillation marks

31

scissors

32

Hot strip mill

33

Mill stands

34

Pouring direction / transport direction

Claims (15)

Process for descaling, in particular surfaces (2, 3) with oscillation marks (30) of a cast strand (1) which can be produced by the continuous casting process, in particular thin slabs, which are carried out in a subsequent hot strip mill (32) with a compensating furnace (11) and preferably with a plurality of roll stands (33 ) be reduced in thickness,
characterized, that the cast strand (1) between the end of the strand support (10) and before the entry into the compensating furnace (11) or before the entry into the roll stands (33) in a limited area (29) by at least twice deflecting from its horizontal transport direction in Area of each deflection (4, 5) is subjected to an expansion of its surfaces (2,3), and that the strand surfaces (2, 3), in particular in the deflection areas (4, 5), are subjected to intensive cleaning by means of hard water jets (8, 9). The method of claim 1
characterized,
that the cast strand (1) is deflected sinusoidally or approximately sinusoidally. The method of claim 1 or 2,
characterized,
that the extent of each deflection (4, 5) of the cast strand (1) is carried out in accordance with the maximum permissible deformation of the cast strand (1). The method of claim 1 or 2,
characterized,
that the extent of each deflection (4, 5) of the cast strand (1) is carried out in accordance with the maximum permissible surface tension of the cast strand (1). The method of claim 1 or 2,
characterized,
that the extent of each deflection (4, 5) of the cast strand (1) according to the material temperature of the cast strand (1) is carried out under constant temperature control. Method according to one or more of claims 1 to 5,
characterized ,
that the distance between spray nozzles (6, 7) and the water-irradiated surface (2, 3) of the cast strand (1) is continuously measured and kept constant. Method according to one or more of claims 1 to 6,
characterized ,
that the pressure of the spray water is continuously checked and kept at a high pressure level. Method according to one or more of claims 1 to 7,
characterized ,
that the cast strand (1) is acted upon by a number of water jets (8, 9) running in parallel planes (xx) and arranged in a row, the planes (xx) being at an angle (α or β) to the transport direction of the Cast strand (1) perpendicular cutting plane (yy) and the water jets (8, 9) obliquely to the surface (2, 3) of the cast strand (1) can be aligned. A method according to claim 8,
characterized,
that the water jets (8, 9) can be moved back and forth in the plane (yy) with the spray nozzles (6, 7) of the spray bars (17, 18) that produce them. Method according to one or more of claims 1 to 9,
characterized,
that the deflection force, which changes according to the structural state of the cast strand (1) in accordance with the cooling taking place with the descaling, is continuously measured and then the amount of water to be dispensed is set constant while maintaining the product of the amount of water and the water pressure. Device for descaling surfaces (2, 3), in particular having oscillation marks (20), of a cast strand (1) which can be produced by the continuous casting process, in particular thin slabs, for carrying out the method according to claims 1 to 10, the cast strand (1) being carried out in a subsequent hot strip mill ( 32) is reduced in thickness with a compensating furnace (11) and preferably with a plurality of roll stands (33),
characterized,
that at the end of the strand support (10) and before entering the equalizing furnace (11) or before entering the rolling stands (33), a descaling station (14) is present between a pair of directional driver rollers (12) on the inlet side and a pair of bending driver rollers (13) on the outlet side which has at least two mutually opposite deflection bending rollers (15, 16) which are spaced apart in the transport direction of the cast strand (1) and which have spray bars (17, 18) on each opposite side of the cast strand (1, 18) with spray nozzles (6 , 7) are assigned. Device according to claim 11,
characterized ,
that the spray bars (17, 18) distance sensors (19, 20) and distance adjusting means (21, 22) are assigned. Device according to claim 11 or 12,
characterized,
that the deflection bending rollers (15, 16) are controlled adjusting cylinders (23, 24) and displacement sensors (25, 26) are assigned. Device according to one or more of claims 11 to 13,
characterized,
that control cylinders (23, 24) are assigned control means for monitoring the deflection forces. Device according to one or more of claims 11 to 14,
characterized,
that the descaling station (14) is covered with a protective box (27).

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