EP2782688A1

EP2782688A1 - Method and device for cleaning a surface of a steel product

Info

Publication number: EP2782688A1
Application number: EP12788555.6A
Authority: EP
Inventors: Eberhard Sowka
Original assignee: ThyssenKrupp Steel Europe AG
Current assignee: ThyssenKrupp Steel Europe AG
Priority date: 2011-11-25
Filing date: 2012-11-22
Publication date: 2014-10-01
Anticipated expiration: 2032-11-22
Also published as: EP2782688B1; US20140290704A1; WO2013076187A1; CN104066524A; ES2556038T3; DE102011119334A1; CN104066524B

Abstract

The invention relates to a method and to a device for cleaning a surface of a steel product (3). In the method, a liquid jet (S1) is directed at the surface (2) from a nozzle (6), which is located at a position associated with an edge (11) of the surface (2) to be cleaned, relative motion occurs between the nozzle (6) and the steel product (3) during the cleaning process, and the liquid jet (S1) is oriented perpendicular to the direction (R) of the relative motion of the steel product (3) and the nozzle (6). According to the invention, in order in particular to minimize the danger of cracks forming on the edges of the steel product to be cleaned, an additional liquid jet (S2) oriented perpendicular to the direction (R) of the relative motion between the nozzles (6, 7) and the steel product (3) is directed at the surface (2) from an additional nozzle (7) without intersecting with the first liquid jet (S1), said additional nozzle being located at a position associated with the edge (12) of the surface (2) that is opposite the edge (6) of the steel product (3) associated with the first nozzle (6), wherein the incidence region (AB1, AB2) of the liquid jets (S1, S2) is at a distance from the edge (11, 12) associated with the nozzle (6, 7) that outputs the liquid jet (S1, S2).

Description

Method and apparatus for cleaning a surface of a steel product

The invention relates to a method for cleaning a surface of a steel product, wherein a jet of liquid is directed onto the surface to be cleaned from a nozzle which is located at an edge of the surface to be cleaned. During the cleaning process, a relative movement takes place between the nozzle and the steel product and the

Fluid jet is transverse to the direction of

Oriented relative movement of steel product and nozzle.

The invention also relates to a device suitable for carrying out such a method, which has a nozzle associated with an edge of the surface of the steel product to be cleaned for discharging a first nozzle

Fluid jet has.

The term "steel products" are here in particular slabs, thin slabs or flat steel products, such as thin slabs or slabs hot rolled hot strip or

sheet metal, each having at least one level, across the width of the respective steel product

have extending surface. Methods and devices of the type according to the invention are in particular for use in a so-called

Casting plant determined. In such plants is in a continuous production process

Molten steel melt into a strand, from which then thin slabs with a thickness, which is typically up to 100 mm, are divided, which are then hot rolled in a standing in line with the caster hot rolling line to a hot strip. Between their production and the hot rolling pass through the thin slabs

if necessary, a furnace in which they are brought to the optimal temperature for hot rolling.

It is important in the production of steel products

at least one of the surfaces of the respective intermediate product present at any given time during the manufacturing process,

Reaction products resulting from the reaction of existing on the surface of the steel product

Steel components with the ambient atmosphere arise. In order to ensure an optimal surface finish of the hot strip, for example, in the production of hot strip in a Gießwalzanlage the above-mentioned type of hot-rolling on the respective

Thin-slab-adhering scale is largely removed before the thin slab enters the first rolling stand of the hot-rolling line.

If scale particles on the surface of a

Flat steel product when entering a rolling stand each hot-rolling slab are present, so they are registered with the nip and lead to defects in the form of so-called

"Zunderschiffchen" on the surface of the preserved

Hot strip. These tinder boats are high grade

problematic, since they are bad ausbeizbar, cause increased roughness on the strip surface and in the case that the hot strip with a metallic, before

Corrosion protective layer to be coated,

Can cause coating defects.

In the case of increased occurrence of scale deposits on the steel product to be rolled in each case, the problem is to be expected that the working rolls coming into contact with the scale-bearing surface of the

Rolling stands are damaged. Thus, it may come to peeling off roll material or it may accumulate scale on the roll surface. Both events can cause so-called "scale marks" on the rolled strip and lead to increased wear of the rolls of the affected rolling stand.

On the steel strip existing dirt and

Reaction products can be put through in practice

Remove high pressure jets from the affected surface. In this case, a highly pressurized liquid jet is directed to the surface to be cleaned. The adhering to the surface

Contaminations and oxide accumulations are said to be due to the high kinetic energy impinging on them

Liquid jet separated from the surface and the effluent from the steel product be washed away. Water is typically used as blasting liquid.

In practice on cast rolling mills for cleaning of

Thin slabs used before hot rolling

Blasting devices usually comprise at least one on the operating side in front of the first rolling stand

Rolling arranged nozzle device, the surface of the guided on rollers slabs with a water jet at a fixed flat angle

applied. It has proved to be problematic in this case that it is only possible to react poorly with such jet devices if steel products are used successively

different width to be processed. So must always with the known jet devices

ensure that the liquid jet in each case the entire width of the surface to be cleaned

evenly swept over. In addition, it has been shown that in such a way with a liquid jet

executed surface cleaning the risk of

Cracking in the area of the liquid jet

struck edges of the steel product consists.

Against this background, the object of the invention was to provide a method and apparatus for removing adhering to the surface of a steel product

To create pollutions and oxidation products, which can be easily adapted to changed dimensions of each steel product to be cleaned and at the same time the risk of

The formation of cracks at the edges of the steel product to be cleaned is minimized. With regard to the method, this object has been achieved according to the invention in that such a method comprises the steps specified in claim 1.

With respect to the device, the above object has been achieved according to the invention in that such a device has the features mentioned in claim 12.

Advantageous embodiments of the invention are specified in the dependent claims and are explained in more detail below as the general inventive concept.

Accordingly, in accordance with the beginning

indicated prior art in the invention

Method for cleaning a surface of a

Steel product from a nozzle, which is located at an edge of the surface to be cleaned, a liquid jet directed to the surface to be cleaned. At the same time during the cleaning process, a relative movement between the nozzle and the steel product takes place. The liquid jet is transverse to the direction of the relative movement of

Steel product and nozzle aligned.

According to the invention, another nozzle, which is located at a position adjacent to that edge of the surface to be cleaned, faces the edge of the steel product associated with the first nozzle, another aligned transversely to the direction of relative movement between the nozzles and the steel product

Liquid jet in relation to the first Liquid jet overlap on the zu

directed to cleansing surface.

At the same time according to the invention is the respective

Impact region, in which the liquid jets meet each of the surface to be cleaned, spaced from the edge, which is associated with the respective liquid jet emitting nozzle.

A device according to the invention for carrying out the method according to the invention accordingly has a nozzle assigned to an edge of the surface of the steel product to be cleaned for discharging a first one

Liquid jet, wherein according to the invention a second nozzle for discharging a second directed onto the surface of the liquid jet is provided, wherein the second nozzle to the edge of the surface to be cleaned

is assigned, which is opposite to the edge, which is associated with the other liquid jet emitting nozzle, and wherein the nozzles are aligned such that the fluid jets they discharge meet without overlap in an impact area on the surface to be cleaned of the steel product, which is spaced apart the edge to which the respective

Liquid jet emitting nozzle is associated.

According to the invention, the cleaning of the respective surface of the steel product is carried out by liquid jets, which are applied from opposite edges of the steel product and directed in their flow direction against each other. The liquid jets are aligned so that their impact areas in the direction the relative movement seen in a central region of the surface to be cleaned overlap.

If here the term "across the direction of the

Relative movement "is used to describe the orientation of the liquid jets, then it is meant any orientation that is transverse to the direction of the

Relative movement directed component, ie in principle each deviating from a parallel to the direction of relative movement alignment. Seen in plan view of the surface to be cleaned, the

Fluid jets thus the direction of the

Relative movement or aligned in the direction of relative movement straight line in each case at an angle of, for example, 30 - 90 intersect, wherein at a relative to the direction of the relative movement or a correspondingly aligned straight orthogonal

Alignment of the liquid jets optimal

Cleaning results are expected.

Due to the non-overlapping alignment of the

according to the invention in opposite directions

Liquid jets will prevent the

Liquid jets hit and kinetic energy is lost through a collision, which then no longer removes the surface to be cleaned

existing contaminants, oxides and deposits is available.

At the same time, the liquid jets

According to the invention aligned so that they

each cleaning surface at a certain distance meet the edge, which is associated with each of them discharging nozzle. The impact area of the

Liquid jets are therefore arranged offset in the direction of the respective opposite edge of the surface to be cleaned. As a result, the edge region of the surface to be cleaned, which adjoins the surface edge assigned to the respective nozzle, does not directly emerge from the nozzle associated with this edge

Struck liquid jet, but only swept by that liquid jet, which of the

opposite edge of the surface associated nozzle is discharged. Since the latter liquid jet has already traveled a greater distance on its way to the relevant edge region, it only hits the critical edge region with a lower kinetic energy. Alternatively, the impact area of the liquid jet can be focused on the surface to be cleaned in such a way that the liquid of the

Liquid jet only rinsed the critical area in a shooting flow, without the liquid jet directing a direct impulse to the critical edge area. As a result, a less rugged cooling of the edge area is achieved so that the otherwise existing risk of stress cracking due to overcooling is minimized.

Another advantage of the inventive provision, the liquid jets to hit with a certain distance from its edge on the surface to be cleaned and provide at least two of opposite sides and in opposite directions flowing liquid jets, is that in this way without major alterations or major adjustment effort

Surfaces of different widths with the same

Device operated according to the invention can be cleaned. It is only essential that between the edge, which is assigned to the respective liquid jet emitting nozzle, and the impingement of the

a sufficient distance is present, that the critical marginal edge region is not hit directly by the liquid jet.

The impact areas of flowing in opposite directions, but not crossing each other

Liquid jets on the surface to be cleaned according to the invention are aligned so that the

total cleaning surface is swept over its entire width by liquid. In the most extreme case, the liquid jets could be aligned so that their impact area in their respective

Seen flow direction begins at the center line of the surface to be cleaned. In this case, the one liquid jet would cover one half and the other liquid jet the other half of the surface to be cleaned. Because such an exact

Alignment in practice, however, usually can not be accomplished with the necessary reliability and to have a good cleaning action specifically in the

Center area of the surface to be cleaned

However, it is advantageous if in

Direction of flow of the respective liquid jet seen the impact area of the liquid jets each begins between the center line of the steel product and that edge of the steel product, the respective liquid jet emitting nozzle

assigned.

In practice, the distance KR between the beginning of the impingement of the respective liquid jet and the edge, which the respective

Fluid jet emitting nozzle is assigned, depending on the width B of the steel product and the width KA, over which the of the den

According to the formula, overlapping liquid jets applied to opposite edges of the steel product associated nozzles overlap in the direction of relative movement

KR ^ 0.5 x (B - KA) can be estimated. It will

in that the condition KA ^ B - 60 mm is maintained, the distance KR thus each at least 30 mm

is sufficient to ensure a sufficient distance to the respective edge.

Due to the fact that a distance KR of at least 30 mm

is complied with, it is ensured under the conditions prevailing in practice that the marginal edge regions of the steel product to be cleaned, which are critical for rapid cooling, are not directly separated from the

Liquid jet are hit and there a

optimal ductility avoiding cracking is maintained. Depending on the respective width of the too

cleaning surface and the available plant technology have in practice distances between the beginning of the impact area of the respective

Liquid jet and that edge, which is assigned to the respective liquid jet emitting nozzle, proven of 30 - 500 mm, in particular 30 - 200 mm. In order to ensure optimum cleaning action in the center region of the surface to be cleaned, it is favorable if the impact areas of the liquid jets overlap in the direction of relative movement over a width which corresponds to at least 20% of the distance which exists between the edges of the steel product, which are associated with the liquid jets emitting nozzles. In the case of cleaning the surfaces of thin slabs where the width of the to be cleaned

Surface today typically in the range of

900 - 2100 mm, in particular 900 - 1600 mm, it has proved in practical experiments to be favorable if the impact areas of the liquid jets are each selected so that in the direction of

Relative movement seen adjusts an at least 500 mm wide overlap area.

According to the invention, the liquid jets are directed onto the surface to be cleaned in such a way that, via their impact area, they remove any dirt present on the surface to be cleaned

apply sufficient impulse. For this purpose, with appropriately designed commercial spray nozzles, the liquid jets on a certain

Spray angle area fanned out. In practice, this spray angle have proven to be between 10 ° and 45 °, preferably between 15 ° and 30 °. If the fanning out is too small, the flow directly overflowed by the respective liquid jet

Impact area has been found to be too small to reliably remove scale particles adhering to the surface. The procedure according to the invention and a device according to the invention are particularly suitable

advantageous to use for cleaning flat surfaces, such as those in cuboid steel products, in particular slabs or thin slabs, are present, in which the surface to be cleaned in each case extends just over the width and length of the steel product. Thus, the invention is particularly suitable in one

Casting rolling plant for cleaning during hot rolling with the work rolls of the rolling mills of the hot rolling line in

Contact coming thin slab surfaces, wherein the inventive cleaning of these surfaces before the entry of the respective thin slab in the first

Hot rolling mill takes place. Another example of

Steel products for which the invention is particularly suitable are flat steel products, such as hot rolled

Steel bands or sheets. Here is the invention

for example, following a conventional

Descalers or scale scrubbers are used to gently remove after the breaking of the scale on the steel strip existing scale from the surface of the flat steel product.

In principle, it is conceivable that the edges of the surface to be cleaned associated with the nozzles

Liquid jets are applied, so to arrange above the surface to be cleaned, that they are in

Top view of the surface to be cleaned viewed in the direction of their respectively assigned edge offset each sit within the surface to be cleaned. However, according to a robust and functionally stable embodiment of the invention, the nozzles are arranged so that they are arranged during the cleaning process with a certain distance laterally next to their respective associated edge of the steel product to be cleaned. The spacing in question is advantageously dimensioned such that the width spectrum provided for the steel products to be cleaned according to the invention is the

Can pass through the device according to the invention without an adjustment of the distance of the nozzle must be made.

The relative movement between the to be cleaned

Steel product and the liquid jets in

According to the invention performing nozzle can be effected in that the nozzles are moved along their associated edges of the surface to be cleaned. In production processes in which the steel product is conveyed in a continuous process on a conveyor line from one to the next processing station, however, it is expedient if the nozzles are arranged stationary and the movement of the already provided

Steel product is used for the relative movement. Such conditions are for example when cleaning

Thin slabs in the feed to the hot rolling line of a

Casting mill given.

An optimally uniform cleaning effect can be achieved by aligning the liquid jets, which are applied in accordance with the invention, parallel to one another. The non-intersecting alignment of the liquid jets across the direction of

Relative movement can thereby be accomplished in a simple manner that in the direction of As seen relative movement between the nozzles and the steel product, the nozzle associated with one edge is positioned offset from the nozzle associated with the other edge. In this way, the distance between both the liquid jets as well as their respective

Increase impact areas arbitrarily, creating a

mutual influence of the two liquid jets can be avoided even after their respective impact on the surface of the flat steel product.

Alternatively it is also possible to use the nozzles directly

To arrange opposite to each other and align the liquid jets discharged by them so that they intersect the center line of the surface to be cleaned each at an acute angle. Again, a parallel alignment of the liquid jets can be made to achieve an intense uniform cleaning effect.

The angle of incidence of the jets of liquid can also be influenced by the height at which the nozzles are in relation to the surface to be cleaned

Flat steel product are arranged. The farther the nozzles are from this surface, the steeper the impact of the liquid jets. At too steep an angle of incidence of the liquid jets, however, there is a risk that they are reflected too much. Therefore, according to another practical embodiment of the invention, the respective solder spacing of the nozzles to the surface to be cleaned of

Flat steel product not more than 45%, in particular not more than 12,5%, of the maximum width of the flat steel product. at a typical in practice width of the

Flat steel product of 900 - 1600 mm this corresponds to a Lotabstand of at most 700 mm, preferably one

Solder distance of at most 200 mm. To ensure that the nozzles do not interfere with the steel product to be cleaned under the conditions prevailing in practice

collide, the minimum distance between the nozzles and the surface to be cleaned in height should be at least 20 mm, in particular at least 40 mm.

The angle of incidence of the liquid jets on the surface to be cleaned is also determined by the angle of inclination enclosed by an obtuse angle between a vertical and the central axis of the liquid jets, below which is the central axis of the jets of liquid discharged from the jets

aligned, determined. To prevent the jets of liquid from wholly or partially passing the surface of the flat steel product, the jets should not be directed away from the surface to be cleaned. At the same time, the angle of inclination should also not be too great to prevent the liquid jets at too steep an angle of impact on the

cleansing surface. Accordingly, according to an advantageous embodiment of the invention is the

Inclination angle in the range of> 90 ° - 135 °, in particular> 90 ° - 105 °, so that the central axis of

Liquid jets with horizontal alignment of the surface of the steel product to be cleaned at an angle of> 0 ° - 45 °, in particular> 0 ° - 15 °, to the

cleansing surface meets. Of course, the edges of the surface to be cleaned of the steel product may be assigned to two or more nozzles, if appropriate, for example, to increase the productivity or to even out the cleaning result.

The inventive method and the device according to the invention are particularly suitable for use in cast rolling, strip casting or hot strip mills for cleaning slabs, thin slabs, cast strip or hot rolled steel strips ("hot strips").

The invention is based on

Embodiments explained in more detail. Each show schematically:

Fig. 1 a on a roller table of a casting rolling mill

arranged device for cleaning the surface of thin slabs in plan view of the surface to be cleaned of the thin slab;

FIG. 2 shows the device according to FIG. 1 in a view from the front; FIG.

Fig. 3 shows the device according to FIGS. 1 and 2 in one

lateral view.

The device 1 for cleaning a surface 2 of a cuboid thin slab 3 is arranged on a roller table 4, on which the thin slab 3, for example, to the first rolling stand of a not shown here Hot rolling line is transported, which is part of a cast rolling mill also not shown here.

The thin slab 3 has, for example, a thickness D of 60 mm, a width B of 1500 mm and a length L of 40 m. The cleaned to be largely flat surface 2 is here on the exposed upper side of the thin slab 3, with their to the

cleaning surface 2 opposite bottom on the rollers 5 of the roller table 2 lying in the conveying direction R is moved. The thin slab 3 is so in one

rectilinear relative movement along the fixed

arranged device 1 promoted. The thin slab 3 is in relation to the width B4 of the roller table 4 in

Aligned substantially centrally, so that in the conveying direction R of the relative movement extending

Center line M of the surface to be cleaned 2 under optimum operating conditions seen in plan view (Fig. 1) coincides with the center line of the roller table 4.

On the surface to be cleaned 2 of the thin slab 3 are scale particles and others from the

previous steps in thin slab production.

The device 1 for cleaning the surface 2 comprises two nozzles 6, 7, of which the one nozzle 6 on the so-called operator side 8a of the roller table 4, from which usually service work on the roller table. 4

be made, and the other nozzle 7 is arranged on the so-called Äntriebsseite 8b of the roller table 4, at which the sake of clarity not here shown drives the rollers 5 of the roller table 4 are located.

The nozzles 6, 7 may be, for example

Conventional flat jet nozzles and flat jet tongue nozzles act.

The liquid jets S 1, S 2 are made of water, which is supplied with a sufficiently high pressure via a supply device (not shown here) to the nozzles 6, 7.

The nozzles 6,7 are each on a frame 9,10

attached, over which their height h over the surface to be cleaned 2, the distance b to their respective associated edge 11,12 of the thin slab 3 and between the

Vertical V and the central axis A of the nozzles 6, 7 respectively discharged liquid jets S1, S2 measured inclination angle Θ can be adjusted. The nozzles 6,7 are to each one horizontally

aligned support arm 13,14 of the frames 9,10 mounted so that they are seen in the direction of conveyance R at a distance c offset from one another. The maximum spacing of the nozzles 6, 7 is dimensioned such that the entire width spectrum in which the thin slabs can be produced in the cast rolling mill can pass through the device 1 without any fundamental modifications.

The nozzles 6,7 bring the liquid jets S1, S2 in the manner of a cutting knife jet in such a way that, in

Seen top view, its central axis A, the center line M of the surface to be cleaned 2 under a right Angle intersects and on the one hand the measured in the conveying direction R width BS of the liquid jets Sl, S2 each is closely limited and on the other hand, the liquid jets S1, S2 after leaving the nozzle 6,7 under a

Fan spray angle γ. The alignment of the nozzles 6, 7 and the liquid jets S1, S2 discharged by them is simultaneously selected such that the

Liquid jets S1, S2 parallel to each other and with opposite aligned

Flow directions SRl, SR2 to be cleaned

Surface 2 of the thin slab 3 meet without getting

to interfere with each other by overlapping. The

Impact areas 15, 16, in which the liquid jets S1, S2 strike the surface 2 to be cleaned, are at a distance KR from the respective one

Liquid jet S1, S2 emitting nozzle 6,7

associated edge 11,12 arranged so that the

Liquid jets S1, S2 seen in the conveying direction R (Fig. 2) via an ideal to the center line M

overlap symmetrically oriented width KA.

In the adjacent to the respective edge 11,12, each extending over the distance KR and the length L of the thin slab KR edge region 17,18 hits the one

Liquid jet S1, S2, which is discharged from the respective edge 11,12 associated nozzle 6,7, therefore not directly on. Instead, the respective edge regions 15, 16 are only washed over by the liquid jet S2, S1, which is ejected by the nozzle 7, 6 arranged on the respectively opposite side. The distance KR is in practice 30-200 mm,

preferably 100-150 mm to ensure that the edges on the lateral edges 11,12 of the surface 2 are not hit. In this way, sufficient to avoid edge errors during subsequent hot rolling ductility of the thin slab 2 in the

Edge areas 15,16 guaranteed.

The width KA of the overlap of the liquid jets S1, S2 should in practice be at least 250 mm in order to ensure sufficiently intensive cleaning of the center region of the surface 2 to be cleaned.

The spray angle γ should be in the range of 10 - 45 °,

in particular 10 to 30 °. At one too low

Spray angle γ sweep the liquid jets S1, S2 when hitting the surface to be cleaned 2 too small impact area AB1, AB2, so that no sufficient cleaning or removal loser

Scale particle occurs. At a clear

Exceeding 45 °, however, the spray fan is too spread and the achievable by the impact and flow of the liquid jet impulse is too low for adequate cleaning.

The greater the height h of the nozzles is selected over the surface to be cleaned 2, the greater the should

Inclination angle Θ be selected in order to reach with the underside of the water fan formed from the respective liquid jet S1, S2 the predetermined impact area AB1, AB2 on the surface 2 to be cleaned. At a height above 700 mm, this angle would be the case today usual thin slabs 3 so steep that the respective

Liquid jet S1, S3 when hitting the

Surface 2 would be strongly reflected upwards and no adequate cleaning would be given. A significant drop below 20 mm is not appropriate, since then there is a risk that the nozzles 6, 7 are damaged as a result of a collision with a non-centric transported over the roller table 4 thin slab 3.

The inclination angle Θ is chosen as a function of the height h so that the water fan formed from the respective liquid jet S1, S2 the predetermined

Impact area ABl, AB2 safely reached. Inclination angles Θ significantly below 90 ° are usually not

makes sense, because then most of the splash water shoots unused on the thin slab. Angle much greater than 135 ° are also not useful, because then they are so steep that the water jet could be reflected strongly when hitting the top of the slab up and no sufficient cleaning would be given.

The distance c of the two liquid jets S1, S2 from each other in the direction R of the relative movement is chosen so that the liquid jets are not

hinder each other.

With the schematically shown in the figures

Device 1 ten attempts El - E10 have been performed. The parameters set width B of each cleaned thin slab 3, spray angle γ of the nozzle 6,7, inclination angle Θ, distance KR, width KA of the overlap region, height h of the nozzle 6,7 on the zu cleaning surface 2, lateral distance b of the nozzles 6,7 to the thin slab 3 and distance c of the

Liquid jets Sl, S2 in the conveying direction R and the nozzle type used in each case, an evaluation of the finished strip in the form of Zundereinwalzungen

detectable "scale error" and an assessment of the edge defects that occurred during subsequent hot rolling are given in Table 1.

It was found that in the case of the procedure according to the invention (tests El-E10), at most only a few slight errors

(Assessment "+") or no errors (assessment "++") are determined on the hot strip produced in each case from a thin slab 3 in accordance with the invention.

For comparison, two further attempts V1, V2 have been carried out with a device not shown here, the basic structure of which corresponded to the device 1, but with two nozzles on the same side 11

have been set up and have been directed without adherence to a distance KR on the edge of each slab to be cleaned. However, this arrangement had significant errors

(Rating "-") or many serious errors (rating "-") result.

REFERENCE SIGN

1 Device for cleaning the surface of

Thin slab 3

2 surface to be cleaned of the thin slab 3

3 thin slab

4 roller table

5 rolls of roller table 2

6.7 nozzles for discharging the liquid jets

Sl, S2

8a operator side of the roller table 4

8b drive side of the roller table 4

9,10 racks

11,12 edge of the surface 2 to be cleaned

Thin slab 3

13,14 support arm of the racks 9,10

15,16 impact areas of the liquid jets S1, S2 on the surface 2 to be cleaned

17,18 edge areas of the surface to be cleaned 2 γ spray angle

Θ Inclination angle

b distance of the nozzles 6,7 to them respectively

associated edge 11,12 of the thin slab 3 c distance

h height of the nozzles 6,7

A respective central axis of

Liquid jets Sl, S2

ABl, AB2 impact area of the liquid jets Sl, S2

B Width of the thin slab 3

B4 width of the roller table 4

BS width of the liquid jets S1, S2

D Thickness of the thin slab 3

KA width over which the liquid jets in

Overlap conveying direction R seen

KR distance to the respective liquid jet

S1, S2 emitting nozzle 6,7 associated edge 11, 12th

L length of the thin slab 3

M center line of the surface to be cleaned 2

R conveying direction in which the respective thin slab 3 is moved relative to the stationary arranged nozzles 6,7

S1, S2 liquid jets

SR1, SR2 Flow direction of liquid jets S1, S2 V Vertical

Claims

P A T E N T A N S P R E C H E

1. A method for cleaning a surface of a

Steel product (3), comprising a nozzle (6) located at one edge (11) of the one to be cleaned

Surface (2) assigned position, a liquid jet (Sl) to be cleaned

Surface (2) is directed, in which during the cleaning process, a relative movement between the nozzle (6) and the steel product (3) takes place and in which the liquid jet (Sl) transversely to the direction (R) of the relative movement of steel product (3) and nozzle (6) is aligned by

g e k e n c i n e,

- That from a further nozzle (7) which is located at one of those edge (12) of the surface to be cleaned (2), which is opposite to the first nozzle (6) associated edge (6) of the steel product (3), a further liquid jet (S2) oriented transversely to the direction (R) of the relative movement between the nozzles (6, 7) and the steel product (3) is directed onto the surface (2) to be cleaned without any overlap in relation to the first liquid jet (S1), and

- That the respective impact area (AB1, AB2), in which the liquid jets (S1, S2) meet each on the surface to be cleaned (2), is spaced from the edge (11,12), that of the respective Liquid jet (Sl, S2) emitting nozzle (6,7) is associated.

2. The method of claim 1, d a d u r c h

g e n c i n e s, s e s in

Flow direction (SR1, SR2) of the respective

Liquid jet (S1, S2) seen in the

Impact area (AB1, AB2) of the liquid jets (S1, S2) in each case between the center line (M) of the surface to be cleaned (2) of the steel product (3) and that edge (11,12) of the steel product (3) begins, the associated with each liquid jet (S1, S2) emitting nozzle (6,7).

3. The method of claim 2, d a d u r c h

e g e s e n e, that is, the distance KR between the beginning of the impact area

(AB1, AB2) of the respective liquid jet (S1, S2) and that edge (11, 12) to which the nozzle (6, 7) discharging the respective liquid jet (S1, S2) is assigned, as a function of the width B of the steel product (3) and the width KA over which the liquid jets (S1, S2) discharged from the nozzles (6, 7) associated with the opposite edges (11, 12) of the steel product (3)

Overlap direction (R) of the relative motion, set according to the following formula:

KR ^ 0.5 x (B - KA). Method according to claim 3, characterized

e g e n e, e s the distance (KR) between the respective impact area

(AB1, AB2) of the liquid jets (S1, S2) and the edge (1,12), which of the respective

Liquid jet (S1, S2) associated with discharging nozzle (6,7) is at least 30 mm.

Method according to one of the preceding claims, characterized in that in the direction (R) of the relative movement seen the impact areas (ABL, AB2) of the liquid jets

(S1, S2) overlap over a width (KA) corresponding to at least 20% of the distance (B) present between the edges (11, 12) of the steel product (3), that of the liquid jets

(S1, S2) emitting nozzles (6,7) are assigned.

Method according to one of the preceding claims, characterized in that the spray angle (γ) over which the respective liquid jet (S1, S2) fans out after exiting the nozzle (6, 7) is 10 ° -45 °.

Method according to one of the preceding claims, characterized in that the angle of inclination (Θ) included as an obtuse angle between a vertical and the central axis (A) of the liquid jets (S1, S2)

> 90 ° - 135 °.

8. Method according to one of the preceding claims, characterized in that the steel product (3) is cuboid and the surface (2) to be cleaned extends in each case just over the width and length of the steel product (3).

9. The method according to any one of the preceding claims, characterized in that the liquid jets (S1, S2) emitting nozzles (6,7) each side of the steel product (3) and spaced from their respective associated edge (11,12) of the steel product ( 3) are arranged.

10. The method according to any one of the preceding claims, characterized in that seen in the direction (R) of the relative movement between the nozzles (6,7) and the steel product (3), the one edge (11) associated nozzle (6) offset from the the nozzle (7) associated with the other edge (12) is positioned.

11. Method according to one of the preceding claims, wherein the nozzles (6, 7) are arranged stationary and the steel product (3) is moved on a conveying path (4) relative to the nozzles (6, 7).

12. The method according to any one of the preceding claims, characterized in that at least the liquid jet (S1, S2) discharged from the one nozzle (6, 7) is aligned orthogonally relative to the direction (R) of the relative movement between the steel product (3) and the nozzles (6, 7).

13. Method according to one of the preceding claims, characterized in casters, cast roll mills or

Hot strip mills for cleaning slabs,

Thin slabs, cast strip or hot rolled steel strips is used.

14. An apparatus for carrying out a method according to any one of claims 1 to 13, wherein the device (1) has a nozzle (6) associated with an edge (11) of the surface (2) of the steel product (3) to be cleaned for discharging a first liquid jet (Sl), characterized in that a second nozzle (7) for discharging a second on the

Surface (2) directed liquid jet (S2) is provided, d a s s the second nozzle (7) the edge (12) of the surface to be cleaned (2)

associated with the edge (11) facing the other liquid jet (S1)

discharging nozzle (6) is assigned, and that the nozzles (6,7) are aligned such that the liquid jets (S1, S2) discharged by them in each case without overlapping Impact area (AB1, AB2) on the surface to be cleaned (2) of the steel product (3) which is spaced from the edge (11,12) to which the respective liquid jet (S1, S2) auszustende nozzle (6,7) assigned.

Use of a device according to claim 14 for cleaning slabs, thin slabs, cast strips or hot strips in strip casting plants, cast roll mills or hot strip mills.