EP2782688B1 - Method for cleaning a surface of a steel product - Google Patents

Description

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 liquid jet is oriented transversely to the direction of the relative movement of the steel product and the nozzle.

Here is a method in which the specified in the preamble of claim 1 steps are completed, already from the JP 03-230809 A known.

The term "steel products" here in particular slabs, thin slabs or flat steel products, such as thin slabs or slabs hot rolled hot strip or sheet combined, each having at least one flat, extending over the width of the respective steel product surface.

Methods of the type according to the invention are in particular intended for use in a so-called "cast roll mill". In such facilities will be in a continuous molten steel, 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. If necessary, between their production and the hot rolling, the thin slabs pass through an oven in which they are brought to the optimal temperature for hot rolling.

In the manufacture of steel products, at various points in the manufacturing process, it is necessary to free at least one of the surfaces of the intermediate product at any one time from any contaminants or reaction products adhering to it which may be due to the reaction of the steel components present on the surface of the steel product 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 continuous casting plant of the above-mentioned type of adhering to each hot-rolling thin slab scale removed as far as possible before the thin slab enters the first rolling mill of the hot rolling line.

If scale particles are present on the surface of a flat steel product when entering a roll stand on the respective slab to be hot rolled, then they are introduced into the roll gap and lead to defects in the form of so-called "Tinder boat" on the surface of the obtained hot strip. These scale boats are highly problematic because they are difficult to salinize, cause increased roughness on the belt surface and, if the hot strip is to be coated with a metallic corrosion preventive layer, can cause coating defects.

In the case of increased occurrence of scale buildup on the respective steel product to be rolled, there is an additional problem to be expected that the work rolls of the rolling stands coming in contact with the scale-bearing surface will be 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 contaminants and reaction products can be removed in practice by high-pressure blasting the respective affected surface. In this case, a highly pressurized liquid jet is directed to the surface to be cleaned. The surface-adhering contaminants and oxide build-up are to be separated from the surface by the high kinetic energy jet impinging on them and swept away from the effluent by the steel product. Water is typically used as blasting liquid.

In practice, used on casting mills for cleaning thin slabs before hot rolling blasting devices usually comprise at least one arranged on the operating side in front of the first stand of the rolling mill nozzle device which acts at a fixed flat angle, the surface of the rollers guided on slabs with a water jet , It has proved to be problematic in this case that it is only possible to react poorly with such jet devices if steel products of different widths are to be processed in succession. Thus, it must always be ensured in the known jet devices that the liquid jet in each case covers the entire width of the surface to be cleaned uniformly. In addition, it has been found that with a surface cleaning carried out in this way with a liquid jet, there is the risk of crack formation in the region of the edges of the steel product struck by the liquid jet.

Against this background, the object of the invention to provide a method for removing adhering to the surface of a steel product contaminants 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 emergence of cracks at the edges of the steel product to be cleaned is minimized.

This object has been achieved by a method with the steps specified in claim 1.

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

Thus, in accordance with the prior art set forth in the method of the invention for cleaning a surface of a steel product from a nozzle located at an edge of the surface to be cleaned, a liquid jet is directed onto 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 aligned transversely to the direction of the relative movement of steel product and nozzle.

In this case, from a further nozzle, which is located at one of those edge of the surface to be cleaned associated with the first nozzle associated with the edge of the steel product, another transverse to the direction of relative movement between the nozzle and the steel product aligned liquid jet with respect to directed the first liquid jet without intersection on the surface to be cleaned.

At the same time, the respective impact area in which the liquid jets strike the surface to be cleaned is at a distance from the edge which is associated with the nozzle delivering the respective liquid jet.

An apparatus for carrying out the method according to the invention accordingly has a nozzle for dispensing a first liquid jet assigned to an edge of the surface of the steel product to be cleaned, a second nozzle being provided for dispensing a second liquid jet directed onto the surface, the second nozzle being adjacent to the edge of the liquid jet is associated with the surface to be cleaned, which is opposite to the edge associated with the other liquid jet emitting nozzle, and wherein the nozzles are aligned such that the liquid jets they impinge meet without interference in an impact area on the surface to be cleaned of the steel product, the is spaced from the edge, which is associated with the respective liquid jet emitting nozzle.

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 of relative movement overlap in a central region of the surface to be cleaned.

Here, when the term "transverse to the direction of relative movement" is used to describe the orientation of the liquid jets, then it is meant any orientation having a direction transverse to the direction of relative movement component, so basically each of a parallel to the direction of Relative movement deviating orientation. Seen in plan view of the surface to be cleaned, the liquid jets can thus intersect the direction of the relative movement or aligned in the direction of relative movement straight at an angle of for example 30-90 °, wherein at one with respect to the direction of the relative movement or a correspondingly aligned straight orthogonal alignment of the liquid jets optimal cleaning results can be expected.

The non-overlapping alignment of the jets of fluid applied in opposite directions prevents the jets of fluid from colliding and losing kinetic energy due to a collision, which is then no longer available to remove the contaminants, oxides and deposits present on the surface to be cleaned.

At the same time the liquid jets are aligned in the process according to the invention so that they meet the surface to be cleaned in each case at a certain distance to the edge, which is assigned to each of them discharging nozzle. The impact area of the liquid jets is accordingly 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 respective nozzle associated surface edge, not hit directly from the nozzle associated with this edge nozzle liquid jet, but only swept by that liquid jet, the 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 overflows 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 rule, 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 can be cleaned with the same device operated according to the invention. It is only essential that there is a sufficient distance between the edge, which is assigned to the respective liquid jet emitting nozzle, and the impingement of the respective liquid jet, so that the critical edge edge region is not hit directly by the liquid jet.

The impact areas of the flowing in opposite directions, but not intersecting liquid jets on the surface to be cleaned according to the invention are aligned so that the surface to be cleaned is swept across over its entire width of liquid. In the most extreme case, the liquid jets could be oriented in such a way that their impact area, viewed in their respective 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. Since such an exact alignment in practice, however, usually can not be accomplished with the necessary reliability and to ensure a good cleaning effect especially in the central region of the surface to be cleaned, it is advantageous if seen in the flow direction of the respective liquid jet of the impact area Liquid jets in each case between the center line of the steel product and that edge of the steel product is assigned, which is assigned to the respective liquid jet emitting nozzle.

For this purpose, according to the invention, the distance KR between the beginning of the impingement of the respective liquid jet and the edge, which is associated with the respective liquid jet emitting nozzle, depending on the width B of the steel product and the width KA, over which the of the opposite edges associated with the steel product Nozzles overlap liquid jets overlap seen in the direction of relative movement, estimated according to the formula KR ≥ 0.5 x (B - KA). Due to the fact that the condition KA ≦ B - 60 mm is maintained, the distance KR thus amounts to at least 30 mm, a sufficient distance to the respective edge is ensured.

By maintaining a distance KR of at least 30 mm, 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 struck directly by the liquid jet and there optimum ductility avoiding crack formation preserved. Depending on the respective width of the surface to be cleaned and the available installation technology, in practice distances between the beginning of the impact area of the respective liquid jet and the edge to which the nozzle discharging the respective liquid jet is from 30 to 500 mm, in particular 30 - 200 mm proven.

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 surface to be cleaned is typically in the range of 900 - 2100 mm, in particular 900-1600 mm, it has proved in practical tests to be favorable if the impact areas of the liquid jets are each selected such that, viewed in the direction of relative movement, an overlap region of at least 500 mm width is established.

According to the invention, the liquid jets are directed onto the surface to be cleaned in such a way that they impart sufficient momentum over their impact area to remove the dirt present on the surface to be cleaned. For this purpose, the liquid jets can be spread fanned over a certain spray angle range with appropriately designed commercial spray nozzles. 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, experience has shown that the impact area directly swept by the respective liquid jet is too small to reliably remove tinder particles adhering to the surface.

The procedure according to the invention can be used particularly advantageously for cleaning flat surfaces, as are present, for example, with cuboid steel products, in particular slabs or thin slabs, in which the surface to be cleaned extends just over the width and length of the steel product. Thus, the invention is particularly suitable in a cast roll plant for cleaning during hot rolling with the work rolls of the rolling stands of the hot rolling line in Contact coming thin slab surfaces, wherein the cleaning of these surfaces according to the invention takes place before the entry of the respective thin slab in the first hot rolling mill. Another example of steel products for which the invention is particularly useful are flat steel products, such as hot rolled steel strip or sheet. Here, the invention can be used, for example, following a conventional descaling or scale scrubber 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 nozzles assigned to the edges of the surface to be cleaned, via which liquid jets are applied, are arranged above the surface to be cleaned in such a way that, viewed in plan view of the surface to be cleaned, they are displaced in the direction of their associated edge, respectively sit to be cleaned surface. According to a robust and functionally stable embodiment of the invention, however, 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 distance in question is advantageously dimensioned such that the width spectrum provided for the steel products to be cleaned according to the invention can pass through the device provided for carrying out the method according to the invention, without having to adapt the spacing of the nozzles.

The relative movement between the steel product to be cleaned and the nozzles discharging the liquid jets in accordance with the invention can be effected by moving the nozzles 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, it is expedient if the nozzles are arranged stationary and the already provided movement of the steel product is used for the relative movement. Such conditions are given for example when cleaning thin slabs in the feed to the hot rolling line of a casting rolling mill.

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-overlapping alignment of the liquid jets transversely to the direction of the relative movement can thereby be accomplished in a simple manner that seen in the direction of the relative movement between the nozzles and the steel product, the nozzle associated with one edge is positioned offset to the nozzle associated with the other edge. In this way, the distance between the two liquid jets as well as their respective impact areas can be arbitrarily increased, whereby 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 arrange the nozzles directly opposite each other and to align the liquid jets they emit so that they each intersect the center line of the surface to be cleaned 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 jets are arranged with respect to the surface of the flat steel product to be cleaned. The farther the nozzles are from this surface, the steeper the angle of impact of the jets of liquid. 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 of the flat steel product to be cleaned is at most 45%, in particular at most 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 a Lotabstand of at most 200 mm. In order to ensure that the nozzles do not collide under the conditions prevailing in practice with the steel product to be cleaned, the minimum distance between the nozzles and the surface to be cleaned should be at least 20 mm in height, in particular at least 40 mm.

The angle of incidence of the liquid jets on the surface to be cleaned is also significantly determined by the included as an obtuse angle between a vertical and the central axis of the liquid jets angle of inclination, under which the central axis of each discharged from the nozzle liquid jets is aligned. 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 from hitting the surface to be cleaned at too steep an angle of impact. Accordingly, according to an advantageous embodiment of the invention, the angle of inclination in the range of> 90 ° - 135 °, in particular> 90 ° - 105 °, so that the central axis of the liquid jets at a horizontal orientation of the surface of the steel product to be cleaned at an angle of> 0 ° - 45 °, in particular> 0 ° - 15 °, strikes the surface to be cleaned.

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 is 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").

Fig. 1

eine an einem Rollgang einer Gießwalzanlage angeordnete Vorrichtung zum Reinigen der Oberfläche von Dünnbrammen in Draufsicht auf die zu reinigende Oberfläche der Dünnbramme;

Fig. 2

die Vorrichtung gemäß Fig. 1 in einer Ansicht von vorne;

Fig. 3

die Vorrichtung gemäß Fig. 1 und 2 in einer seitlichen Ansicht.

The invention will be explained in more detail by means of exemplary embodiments. Each show schematically:

Fig. 1

a device arranged on a roller table of a continuous casting plant for cleaning the surface of thin slabs in plan view of the surface to be cleaned of the thin slab;

Fig. 2

the device according to Fig. 1 in a view from the front;

Fig. 3

the device according to Fig. 1 and 2 in a side 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 is transported, for example, to the first rolling mill of a hot rolling line, not shown here, which is part of a casting rolling plant 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 surface 2 to be cleaned, largely flat, is located here on the exposed upper side of the thin slab 3, which lies with its underside, which is opposite the surface 2 to be cleaned, on the rollers 5 of the roller table 2 in the conveying direction R. is moved. The thin slab 3 is thus conveyed in a rectilinear relative movement along the stationarily arranged device 1. The thin slab 3 is aligned substantially centrally with respect to the width B4 of the roller table 4, so that the center line M of the surface 2 to be cleaned extending in the conveying direction R of the relative movement is seen in top view under optimum operating conditions (FIG. 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 other originating from the preceding steps of the thin slab production contaminants.

The device 1 for cleaning the surface 2 comprises two nozzles 6,7, of which 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 are made, and the other nozzle 7 on the so-called drive side 8b of the roller table 4 is arranged, at which the sake of clarity, not shown drives of the rollers 5 of the roller table 4 are located.

The nozzles 6, 7 may, for example, be conventional flat jet nozzles and flat jet tongue nozzles.

The liquid jets S1, S2 consist 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 fastened to a frame 9, 10, via which their height h is above the surface 2 to be cleaned, the distance b to their associated edge 11, 12 of the thin slab 3 and that between the vertical V and the central one Axis A of the nozzles 6, 7 respectively discharged liquid jets S1, S2 measured inclination angle Θ can be adjusted. For this purpose, the nozzles 6, 7 are respectively mounted on a horizontally oriented support arm 13, 14 of the racks 9, 10 in such a way that, as seen in the direction of conveyance R, they are arranged 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 beam such that, seen in plan view, its central axis A intersects the center line M of the surface to be cleaned 2 at a right angle and on the one hand measured in the conveying direction R width BS the liquid jets S1, S2 are each narrowly defined and, on the other hand, the liquid jets S1, S2 fan out after leaving the nozzles 6, 7 at a 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 meet the surface 2 of the thin slab 3 to be cleaned parallel to one another and with flow directions SR1, SR2 aligned in opposite directions. without interfering 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 arranged at a distance KR from the edge 11, 12 assigned to the respective liquid jet S1, S2, so that the Liquid jets S1, S2 seen in the conveying direction R ( Fig. 2 ) overlap over a width KA symmetrically oriented to the center line M, ideally.

In the adjoining the respective edge 11,12, respectively over the distance KR and the length L of the thin slab KR extending edge region 17,18 that liquid jet S1, S2, which from the respective edge 11,12 associated nozzle 6,7 hits is applied, so 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, a sufficient ductility of the thin slab 2 in the edge regions 15,16 is ensured to avoid edge defects during subsequent hot rolling.

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 - 30 °. If the spraying angle γ is too low, the liquid jets S1, S2 strike an impinging area AB1, AB2 that is too small on impact with the surface 2 to be cleaned, so that there is no adequate cleaning or removal of loose scale particles. On the other hand, with a clear overshoot of 45 °, the spray fan is spread too much and the impulse that can be achieved due to the impingement and outflow of the liquid jet is too small for adequate cleaning.

The greater the height h of the nozzles is selected over the surface to be cleaned 2, the greater the inclination angle Θ should be selected to the underside of the water fan formed from the respective liquid jet S1, S2 the predetermined impact area AB1, AB2 on the surface to be cleaned 2 to reach. At a height above 700 mm, this angle would be so steep in today's conventional thin slabs 3, that the respective liquid jet S1, S3 would be strongly reflected when hitting the surface 2 and no sufficient cleaning would be more. 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 such that the water fan formed from the respective liquid jet S1, S2 reliably reaches the predetermined impingement area AB1, AB2. Inclination angle Θ well below 90 ° are usually not useful, because then shoots most of the splash water 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 do not interfere with each other.

With the apparatus 1 shown schematically in the figures, ten tests E1 - E10 have been carried out. 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 surface to be cleaned 2, lateral distance b of the nozzle 6,7 to the thin slab 3 and distance c of the liquid jets S1, S2 in the conveying direction R and the nozzle type used in each case, an assessment of the "tinder error" which can be detected on the finished strip in the form of Zundereinwalzungen and an assessment of the occurred during subsequent hot rolling edge defects are in the table 1 indicated.

It was found that in the case of the procedure according to the invention (tests E1-E10) only a few slight errors (rating "+") or no errors (rating "++") at most be determined from a thin slab 3 in accordance with the invention each produced hot strip.

For comparison, two further experiments V1, V2 have been carried out with a device not shown here, the basic structure of the device 1 corresponded, but in which two nozzles placed on the same page 11 and without adhering to a distance KR on the edge of each slab to be cleaned have been directed. However, this arrangement resulted in significant errors (rating "-") and many severe errors (rating "-").

REFERENCE NUMBERS

1

Device for cleaning the surface of the thin slab 3

2

Surface to be cleaned of the thin slab 3

3

thin slab

4

roller table

5

Rollers of roller table 2

6, 7

Nozzles for discharging the liquid jets S1, 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 to be cleaned 2 of the 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 regions of the surface 2 to be cleaned

γ

spray angle

Θ

tilt angle

b

Distance of the nozzles 6,7 to their respective associated edge 11,12 of the thin slab. 3

c

distance

H

Height of the nozzles 6,7

A

respective central axis of the liquid jets S1, S2

AB1, AB2

Impact area of the liquid jets S1, 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 thin slab 3

KA

Width over which the liquid jets overlap seen in the conveying direction R.

KR

Distance to the respective liquid jet S1, S2 emitting nozzle 6,7 associated edge 11,12

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 the liquid jets S1, S2

V

vertical

Table 1 No. B [mm] γ [°] Θ [°] KR [mm] Comb] h [mm] b [mm] c [mm] nozzle type scale defects edge cracks E1 1520 15 97 410 700 150 190 150 flat jet + + E2 1280 15 97 290 700 150 310 150 flat jet + ++ E3 961 15 97 130 700 150 470 150 flat jet ++ ++ E4 1075 15 97 188 700 150 413 150 flat jet ++ ++ E5 1387 15 97 344 700 150 257 150 flat jet ++ ++ E6 1416 15 97 358 700 150 242 150 flat jet ++ ++ E7 1459 15 97 380 700 150 221 150 flat jet ++ ++ E8 1555 15 97 428 700 150 173 150 flat jet ++ ++ E9 1561 15 97 431 700 150 170 150 flat jet ++ ++ E10 1593 15 97 447 700 150 154 150 flat jet ++ ++ V1 1280 30 110 0 1280 150 310 100 flat jet - - V2 1270 30 110 0 1270 150 315 100 flat jet - -

Claims (11)

1. Method for cleaning a surface of a steel product (3), in which a fluid jet (S1) is directed from a nozzle (6), which is located in a position which is associated with an edge (11) of the surface (2) to be cleaned, onto the surface (2) to be cleaned, wherein, during the cleaning operation, there is produced a relative movement between the nozzle (6) and the steel product (3) and wherein the fluid jet (S1) is orientated transversely relative to the direction (R) of the relative movement of the steel product (3) and nozzle (6),

   - wherein from another nozzle (7) which is located in a position which is associated with the edge (12) of the surface (2) to be cleaned, which edge (12) is opposite the edge (11) of the steel product (3) associated with the first nozzle (6), another fluid jet (S2), which is orientated transversely relative to the direction (R) of the relative movement between the nozzles (6,7) and the steel product (3), with respect to the first fluid jet (S1) is directed onto the surface (2) to be cleaned without any overlap,

   - wherein the respective striking region (AB1,AB2) in which the fluid jets (S1, S2) strike the surface (2) to be cleaned is spaced apart from the edge (11,12) which is associated with the nozzle (6,7) which produces the fluid jet (S1, S2), respectively and

   - wherein when viewed in the flow direction (SR1, SR2) of the respective fluid jet (S1, S2), the striking region (AB1, AB2) of the fluid jets (S1, S2) begins between the centre line (M) of the surface (2) to be cleaned of the steel product (3) and the edge (11,12) of the steel product (3), which (11,12) edge is associated with the nozzle (6,7) which produces the respective fluid jet (S1, S2)

   characterised in that the spacing (KR) between the beginning of the striking region (AB1, AB2) of the respective fluid jet (S1, S2) and the edge (11,12) with which the nozzle (6,7) producing the respective fluid jet (S1, S2) is associated, is adjusted, in accordance with the width (B) of the steel product (3) and with the width (KA) over which the fluid jets (S1, S2) which are produced by the nozzles (6,7) associated with the opposing edges (11,12) of the steel product (3) overlap when viewed in the direction (R) of the relative movement, according to the following formula: $$\mathrm{KR}\ge \mathrm{0.5}\mathrm{x}\left(\mathrm{B}-\mathrm{KA}\right)\mathrm{.}$$

   
2. Method according to claim 1, characterised in that the spacing (KR) between the striking region (AB1,AB2) of the fluid jets (S1, S2) and the edge (11,12) which is associated with the nozzle (6,7) which produces the respective fluid jet (S1, S2) is at least 30 mm.
3. Method according to any one of the preceding claims, characterised in that, when viewed in the direction (R) of the relative movement, the striking regions (AB1,AB2) of the fluid jets (S1, S2) overlap over a width (KA) which corresponds to at least 20% of the spacing (B) which is provided between the edges (11,12) of the steel product (3) which are associated with the nozzles (6,7) which produce the fluid jets (S1, S2).
4. Method according to any one of the preceding claims, characterised in that the spraying angle (γ) over which the fluid jet (S1, S2) spreads after the discharge from the nozzle (6,7) is from 10° to 45°.
5. Method according to any one of the preceding claims, characterised in that the inclination angle (Θ) enclosed as an obtuse angle between a vertical line and the centre axis (A) of the fluid jets (S1, S2) is > 90° to 135°.
6. Method according to any one of the preceding claims, characterised in that the steel product (3) is parallelepipedal and the surface (2) to be cleaned extends in a planar manner over the width and length of the steel product (3).
7. Method according to any one of the preceding claims, characterised in that the nozzles (6,7) which produce the fluid jets (S1, S2) are each arranged at the side of the steel product (3) and with spacing from the edge (11,12) of the steel product (3) associated therewith.
8. Method according to any one of the preceding claims, characterised in that, when viewed in the direction (R) of the relative movement between the nozzles (6,7) and the steel product (3), the nozzle (6) which is associated with one edge (11) is positioned offset with respect to the nozzle (7) associated with the other edge (12).
9. Method according to any one of the preceding claims, characterised in that the nozzles (6,7) are arranged so as to be fixed in position and the steel product (3) is moved on a conveying path (4) relative to the nozzles (6,7).
10. Method according to any one of the preceding claims, characterised in that at least the fluid jet (S1, S2) which is produced by one nozzle (6,7) is orientated orthogonally relative to the direction (R) of the relative movement between the steel product (3) and the nozzles (6,7).
11. Method according to any one of the preceding claims, characterised in that it is used in strip casting installations, casting and rolling installations or hot-rolling works for cleaning slabs, thin slabs, cast strip or hot-rolled steel strips.

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