EP2866957B1 - Method and device for cooling surfaces in casting installations, rolling installations or other strip processing lines - Google Patents

Description

Field of the invention

The present invention is directed to a method and a device for cooling surfaces in casting plants, rolling mills or other strip processing lines. In this case, cooling medium is preferably applied to the surface of a cast or rolled stock, in particular a metal strip or sheet, or a roll.

State of the art

From the prior art, a variety of methods for cooling metal strips or rolls is known.

The DE 41 16 019 A1 refers, for example, to a device for cooling a metal strip with liquid nozzles arranged on both sides, which are designed as full jet nozzles. Impinging jets are formed by these nozzles, with areas of shooting flow forming around the impact point of the individual impact jets. In this device, the beams hit the belt surface freely and without any guidance or confinement. A disadvantage of such a device, for example, the relatively high water consumption and despite the efforts made difficult to avoid formation of a vapor layer between the firing flow and the surface to be cooled.

The DE 27 51 013 A1 discloses a cooling device in which a spray containing water droplets is generated and directed onto a metal plate to be cooled. The nozzles required for this purpose are designed as Venturi tubes, through which a targeted mixing of air and water is promoted. The resulting multiphase Kühlmittelsfrom leads to a vapor layer formation, which significantly affects the cooling effect.

The JP 2005118838 A discloses a device for cooling by spray nozzles. By using the spray nozzles, a jet of liquid and gaseous components is formed. This also forms a vapor layer on the material to be cooled, which precludes effective cooling.

The JP S57 156 830 A discloses a rolled strip metal cooling apparatus having a nozzle and a plate-like guide extending from said nozzle parallel to the surface of the metal strip to be cooled. The cooling water flowing out of the nozzle forms between the plate-like guide and the surface to be cooled a water film for cooling the metal strip. The nozzle and the plate-like guide are fixedly mounted via a spray bar on a height-adjustable cross member, so that the distance between the nozzle and the surface of the metal strip to be cooled is adjustable by raising and lowering the cross member.

The object of the invention is to provide an improved method for cooling foundry material, rolling stock or rolls. The object is preferably to overcome at least one of the above-mentioned disadvantages. In particular, the required amount of coolant should preferably be reduced or the efficiency, effectiveness and / or flexibility of the cooling should be improved.

Disclosure of the invention

The technical problem is solved by the features of independent claim 1. According to the claimed method for cooling a surface of foundry material, rolling stock (in particular metal strip or sheet metal) or a roll, a nozzle is provided which has an inlet with a first clear or inner cross section and an outlet opposite the surface to be cooled with a second clear or Inner cross-section includes, which is preferably larger than the first cross section. Furthermore, a preferably single-phase volumetric flow of a cooling fluid is provided, which is supplied via the inlet of the nozzle and leaves the nozzle through the outlet. At least the nozzle outlet or the nozzle is stored at a variable (or freely adjustable) distance to the surface to be cooled. The volume flow of the cooling fluid supplied to the inlet of the nozzle is also adjusted in such a way that the nozzle or the nozzle outlet adheres to the surface to be cooled in accordance with the Bernoulli principle (or the hydrodynamic paradox).

Characterized in that the nozzle is stored with a variable or freely adjustable distance to the surface to be cooled and the volume flow of the cooling fluid flowing through the nozzle is adjusted such that it automatically according to the Bernoulli principle (English: Bernoulli's principle) on the surface Suction, effective cooling of the surface is made possible. According to the said principle, when the cooling fluid (for example water, air or an emulsion of water and oil) flows out of the nozzle outlet, a lower pressure (negative pressure) is created relative to the surroundings of the nozzle, which causes the nozzle to contact the vacuum to be cooled surface or in other words, the distance between the outlet and the surface is reduced independently. This can for example be caused by the fact that the flow rate of the fluid flowing out of the outlet is increased, whereby, according to the Bernoulli principle, the pressure of the liquid flowing out of the nozzle is lowered. As a result of this pressure reduction in the region of the flow between the surface to be cooled and the nozzle outlet, a state is reached in which the nozzle on the surface to be cooled becomes saturated due to the pressure difference to the pressure in the vicinity of the nozzle. However, the nozzle does not collide with the surface to be cooled, since the volume flow (permanent) is fed or tracked through the inlet of the nozzle. Thus, at a preferably constant volume flow, a substantially constant distance between the Nozzle outlet and the surface to be cooled guaranteed. This distance is self-regulating or in other words, the distance adjusts itself.

The variable or movable mounting of the nozzle at a distance from the surface may preferably be in a range between 0.1 mm and 5 mm, preferably between 0.5 mm and 2 mm.

Further advantages of the invention include high heat transfer coefficients between the surface to be cooled and the nozzle and an increase in efficiency over known systems. In addition, the length of a cooling device can be reduced when cooling a tape in the direction of tape travel by the increased efficiency. In particular, coolant can be applied directly to a required location, so that, on the one hand, individual areas of the surface to be cooled are specifically cooled and, on the other hand, losses of coolant for cooling are avoided. On the surface vaporizing cooling medium is shielded by the nozzle of the actual cooling zone. Thus, the cooling performance of the nozzle is largely independent of the stray cooling medium. If multiple nozzles are distributed across a roller or belt width, portions of the roller or belt may either be less cooled or remain completely uncooled by shutting off nozzles in those areas.

According to a preferred embodiment of the method, the distance of the outlet is (exclusively) variable in a direction substantially perpendicular to the surface to be cooled. This means that the distance is not limited to a fixed amount. The distance is adjustable by the volume flow.

According to a further preferred embodiment of the method, the nozzle is at least partially slidably mounted by a guide. Such a guide may comprise, for example, a sliding bearing, wherein the nozzle slidably in a sleeve the bearing is slidably mounted. The storage can be made such that only a movement is possible in a direction perpendicular to the surface to be cooled. This ensures a force-free independent adjustment of the distance between the nozzle outlet and the surface to be cooled.

According to a further preferred embodiment of the method, the nozzle is mounted resiliently and / or additionally provided with a damping device. Preferably, the nozzle is biased in a direction perpendicular to the surface direction. It is possible that the surface to be cooled is carried by one or more nozzles. In this case, the prestressed mounting of the nozzles is particularly advantageous because, on the one hand, the surface to be cooled and, for example, rolled or cast material can be carried, but on the other hand, a self-adjusting distance between the surface to be cooled and the strip is made possible. Such nozzles can be arranged both on the top of a metal strip or sheet and on its underside.

According to a further preferred embodiment of the method, the nozzle is substantially parallel to the surface to be cooled, in particular oscillatable by an oscillating device. By such a feature, uneven cooling of the surface can be counteracted. In particular, a larger surface area can be covered with a limited number of nozzles. The oscillation preferably has at least one component perpendicular to the strip running direction or parallel to the axial direction of a roll. Preferably, the oscillation takes place in a plane parallel to the surface to be cooled. In an arrangement with several nozzles, they can also oscillate in different directions and with different frequencies.

According to a further preferred embodiment of the method, the nozzle has a guide region between the inlet and the outlet, in which the coolant is guided substantially in a direction perpendicular to the surface to be cooled and is laterally enclosed by this. In other words, the volume flow is supplied to the outlet substantially perpendicular to its cross-section standing. As a result, unwanted turbulences can be avoided, in particular when using a cooling liquid, which could lead to the formation of air bubbles. Because the heat transfer between the coolant and the surface to be cooled can be significantly improved by avoiding air bubbles.

According to a further preferred embodiment of the method, the cross section of the outlet of the nozzle increases in the direction of the surface to be cooled. By a widening or widening shape of the outlet in the direction of the surface to be cooled, parts of the coolant flow can be deflected in a horizontal direction. Such a shape can further enhance the effect of the suction. Preferably, said expansion is continuous and / or, for example, funnel-shaped or outwardly curved.

According to a preferred embodiment of the method, the second cross section is formed substantially rotationally symmetrical in a plane lying parallel to the surface to be cooled. In other words, the cross section may be substantially circular. By such a configuration, a homogeneous supply of coolant can be achieved.

According to a further preferred embodiment of the method, the nozzle is non-rotationally symmetrical in a plane lying parallel to the surface to be cooled. It is preferably elongate, in particular elliptical. By such a feature, for example, an asymmetric cooling zone can be counteracted with moving cooling surfaces.

According to another preferred embodiment of the method, adjusting the volume flow comprises adjusting it Flow velocity and / or its pressure. The exact values of such a pressure or volume flow depend on the particular geometry and size of the nozzle.

According to a further preferred embodiment of the method, the variable distance between the outlet and the surface to be cooled is kept greater than 0.1 mm and preferably greater than 0.5 mm by a limiting element (irrespective of the volumetric flow provided). By such a limiting element or by such a stop, for example, even in the case of a failure of the volume flow, a collision of the nozzle can be avoided with the surface to be cooled.

According to a further preferred embodiment of the method, a plurality of nozzles are arranged in a grid-like manner in a plane opposite the surface to be cooled. By this grid-like arrangement of nozzles, a large area of the surface to be cooled can be covered. In other words, a plurality of nozzles is arranged side by side opposite the surface to be cooled. Stated differently, multiple nozzles may be arranged in a row, for example, more than four nozzles. In the case of cooling a roller, preferably a plurality of nozzles may be arranged in a direction parallel to the roller axis. In general, several such rows can be provided. In the case of cooling of rolled or cast material, such as a metal strip, such rows may extend transversely to the strip running direction. In addition, several rows can be arranged one behind the other in the strip running direction. It is also possible that the rows are offset relative to one another transversely to the strip running direction, so that viewed in the direction of tape travel, lie in the interstices of two adjacent nozzles of a row, nozzles of an adjacent tape running direction series. It is also possible for individual nozzles or nozzle rows to oscillate in the same direction or at different levels, parallel to the cooling surface, in order to obtain the most uniform possible cooling result.

According to a further preferred embodiment of the method, the outlet of the nozzle is arranged opposite the surface of a roll or arranged opposite the surface of a metal strip, in particular between two roll stands of a rolling train. Especially in such positions, the inventive method is of particular advantage.

In addition, the invention is directed to a cooling device for cooling a surface of a metal strip, a sheet or a roller for carrying out the method according to one of the preceding embodiments. In this case, the device comprises at least one nozzle, comprising an inlet with a first cross section for directing a volume flow and an outlet opposite the surface to be cooled with a second cross section for directing the volumetric flow, which is greater than the first cross section, and wherein the cooling device further such is formed so that the distance of the outlet of the nozzle is perpendicular to the surface to be cooled between 0.1 mm and 10 mm, preferably between 0.5 mm and 5 mm or between 0.5 mm and 2 mm variable or freely adjustable. In particular, the nozzle may be slidably guided by a guide.

Further, the invention is directed to a rolling mill for rolling rolling, which comprises said cooling device. The rolling device comprises at least one roller with a roll surface to be cooled on which the nozzle outlet is directed for cooling the roll surface. Alternatively or additionally, the rolling device comprises at least two rolling stands for rolling a metal strip, wherein a cooling device according to the invention is arranged between the two rolling stands for cooling the surface of the metal strip located between the two rolling stands.

Furthermore, the nozzle is preferably used to locally, that is, at the location of the nozzle, specific structural processes in the body to be cooled (in particular the rolling stock) cause.

All features of the embodiments described above can be combined with each other or replaced.

Brief description of the figures

Figur 1

eine schematische Querschnittsansicht eines Ausführungsbeispiels einer erfindungsgemäßen Düse;

Figur 2

eine schematische Querschnittsansicht eines Ausführungsbeispiels einer erfindungsgemäßen Kühlvorrichtung; und

Figur 3

eine teiltransparente, schematische Draufsicht auf ein weiteres erfindungsgemäßes Ausführungsbeispiel einer Kühlvorrichtung.

The figures of the embodiments will be briefly described below. Further details can be found in the detailed description of the embodiments. Show it:

FIG. 1

a schematic cross-sectional view of an embodiment of a nozzle according to the invention;

FIG. 2

a schematic cross-sectional view of an embodiment of a cooling device according to the invention; and

FIG. 3

a partially transparent, schematic plan view of another inventive embodiment of a cooling device.

Detailed description of the embodiments

The FIG. 1 2 shows a schematic cross section of an embodiment of a nozzle 2 which can be used for the method according to the invention. The illustrated nozzle 2 comprises an inlet 3 and an outlet 5 arranged opposite the surface of a body or belt 1 to be cooled Nozzle 2 preferably has an area for guiding 9 a volume flow V directed into the inlet 3 to the outlet 5. The volume flow V is preferably perpendicular to the to be cooled Standing surface supplied to the outlet 5. The inlet 3 preferably has a smaller clear diameter or cross section E than the outlet 5. In other words, the outlet 5 has a larger clear diameter or cross section A than the inlet region 3 and / or the guide region 9. The nozzle 2 or its outlet 5 widens in the direction of the surface to be cooled and is preferably in the guide region 9 mounted displaceably by a guide element 7 or mounted relative to the surface of the belt to be cooled 1 such that the distance d between the belt to be cooled 1 and the outlet 5 of the nozzle 2 is variable. In this case, the nozzle 2 preferably slides in the guide 7. This movement preferably takes place in a direction S perpendicular to the surface to be cooled. Through the guide 7, the nozzle 2 is particularly secured against tilting moments. From or in the direction S, the nozzle outlet 5 is preferably flown through by the volume flow V of the cooling fluid. Fluids may generally be liquids, in particular water or oil-water mixtures. Alternatively, cooling by gases, such as air or inert gases, is also possible. Preferably, however, a liquid is generally used as the coolant, since in this way higher heat transfer coefficients than in the case of gases can be realized. Preferably, however, only a single-phase cooling fluid should be used. If the volume flow V is adjusted accordingly, the nozzle 2 may become stuck to the surface to be cooled. This is done as already described above according to the Bernoulli principle or in other words according to the hydrodynamic paradox. The adjustment can be done by adjusting the pressure or the speed of the nozzle 2 supplied volume flow V.

The Bernoulli principle itself is known to the person skilled in the art. A corresponding effect, for example, also occurs when passing a car on a truck, wherein, while both vehicles are at the same height, the car is sucked relative to the truck. After passage of the truck, the car moves back across its direction of travel. The while passing through arising suction is caused by the constricted and accelerated air flow between both vehicles. According to the principle of Bernoulli, this narrowed, accelerated air flow results in a negative pressure between both vehicles relative to the air pressure in the remaining environment of the vehicles. However, this discussion is intended to be illustrative only and should not be taken as limiting.

With respect to the invention or the described embodiment, a suction effect occurs when the volume flow V 'emerging from the outlet 5 between the outlet 5 and the surface 1 to be cooled has reached a sufficiently high relative speed, so that the pressure within the between the outlet 5 and the surface 1 to be cooled flowing volume flow V 'below the nozzle 2 surrounding pressure drops. This pressure can correspond to the atmospheric pressure. If the volumetric flow V is kept constant when the suction effect has set, according to the Bernoulli principle there is a self-sustaining equilibrium of forces. If now the distance d between the surface to be cooled and the nozzle outlet 5 is changed, the nozzle automatically restores the distance in the equilibrium of forces. Such variations in distance may be caused, for example, by an irregular surface to be cooled or, for example, by a deformed roll surface or inaccurate guidance of a metal strip 1. The same may apply to the cooling of rolls for irregular roll surfaces.

In general, the nozzle 2 or the method according to the invention can be used on a strip top side, but also on a strip underside.

The FIG. 2 shows a schematic cross section of an embodiment of a cooling device 10 for cooling a metal strip 1. For simplicity, the same reference numerals as in the. For identical or analogous elements FIG. 1 used. The in the FIG. 2 illustrated device 10 has a Variety of nozzles 2, which are fed together by a cooling fluid container 14. The cooling device 10 is arranged in each case on the upper side of the strip and on the underside of the strip for cooling the metal strip 1. The individual nozzles 2 are arranged in the tape running direction B in successive rows. Each row preferably extends transversely to the tape running direction B. These rows may be offset perpendicularly to the tape running direction B, so that viewed in the tape running direction B, a greater part of the width of the tape 1 is covered by the nozzles 2 than by one of the rows. The nozzles 2 are similar as in the FIG. 1 shown in each case with a volume flow V fed via its inlet 3. In this case, the container 14 can be correspondingly under pressure to press the cooling fluid into the inlets 3 of the nozzles 2. The nozzles 2 are slidably guided perpendicularly to the surface to be cooled by guide elements 7 (for example slide bearings), so that the distance d between the nozzle outlet 5 and the surface to be cooled is variable. Nevertheless, the distance d, for example mechanically, may be limited. To prevent a collision with the surface to be cooled, the device 10, in particular the nozzles 2 and / or the guide elements 3, preferably stops 11, which limit the movement of the nozzles 2 in the direction of the surface to be cooled. In addition, the nozzles 2 may be biased by elastic means and / or spring elements 13 substantially in the perpendicular to the surface to be cooled.

Furthermore, it is generally possible for the cooling device 10 to comprise one or more oscillation devices (not shown), which is either designed to oscillate each individual nozzle 2 parallel to the surface to be cooled or to oscillate all the nozzles 2 of the device 10 together. Preferably, an oscillation of the entire container 14 together with the nozzle 2 mounted on this would be possible.

The FIG. 3 shows a partially transparent plan view of an embodiment of a cooling device 10 '. This device 10 'essentially corresponds to that according to FIG FIG. 2 However, six are in the tape direction B provided successively arranged nozzle rows. The device according to FIG. 2 has only four such rows. The nozzles 2 are supplied with cooling fluid by the fluid container 14 '. The fluid emerges in the form of the volume flow V 'from the outlets 5 of the nozzles 2, so that a heat transfer between the belt 1 and the cooling fluid or the volume flow V' can take place. Like in the FIG. 3 As shown, the volumetric flow V 'leaves the outlet 5 of the nozzle preferably and generally in a direction substantially parallel to the surface to be cooled. If the nozzle outlet 5 has the illustrated rotationally symmetric or circular shape, then the volume flow V 'leaving the outlet moves substantially concentrically away from the nozzle 2.

In general, a nozzle 2 according to the invention may have different shapes, such as slit-like or round shapes. In a slit-like configuration, the nozzle 2 may extend at least over part of the width of the surface to be cooled, such as across the width of a roll or a metal strip.

In general, however, the cross-section of the nozzles 2 or of the nozzle outlet 5 can likewise be adapted to an asymmetrical effective range which arises as a result of a movement of the surface to be cooled.

The clear diameter of the nozzle outlet may furthermore preferably be between 0.5 cm and 10 cm or preferably between 1 cm and 5 cm.

In the case of cooling with a gas, such as air or an inert gas, the distance between the outlet 5 of the nozzle 2 and the surface to be cooled may for example be between 0.1 mm and 5 mm, or preferably between 0.1 mm and 3 mm.

In the case of cooling with a liquid, such as with water, a water mixture or an emulsion, the distance between the outlet 5 of the nozzle 2 and the surface to be cooled, for example, between 0.5 mm and 5 mm or preferably between 1 mm and 5 mm or even between 1 mm and 2 mm.

Even smaller distances than those mentioned are generally not advantageous since in such a case an increased risk of a collision between the surface to be cooled and the nozzle 2 would exist. Such a collision can damage the nozzle 2 and / or the surface to be cooled.

If a plurality of nozzles are arranged opposite the surface to be cooled, they may preferably have spacings between one another which correspond to 0.5 times to 5 times or preferably 1 to 2 times the clear diameter of the outlet 5.

Above all, the embodiments described above serve to better understand the invention and should not be understood as limiting. The scope of protection of the present patent application results from the patent claims.

The features of the described embodiments can be combined or replaced with each other.

Furthermore, the features described can be adapted by the skilled person to existing circumstances or existing requirements.

LIST OF REFERENCE NUMBERS

1

Rolling stock, foundry, metal strip or sheet metal

2

jet

3

inlet

5

outlet

7

guide element

9

guide region

10

cooler

10 '

cooler

11

limiting element

13

Biasing element / spring element / damping element

14

fluid container

14 '

fluid container

A

Cross section of the outlet

B

Tape direction

e

Cross section of the inlet

S

vertical direction to the surface to be cooled

V

Volume flow of the coolant

V '

from the outlet of the nozzle exiting flow

d

Distance of the nozzle to the surface to be cooled

Claims (16)

1. Method of cooling a surface of cast material, rolling stock (1) or a roll, comprising the following steps:

   providing a nozzle (2), which comprises an inlet (3) and an outlet (5) which is opposite the surface to be cooled,

   and providing a preferably single-phase volume flow (V) of a cooling fluid, which Is fed to the nozzle (2) by way of the inlet (3) and leaves the nozzle (2) through the outlet (5),

   characterised in that

   at least the nozzle outlet (5) is mounted at a variable spacing (d) from the surface to be cooled and

   the volume flow (V) of the cooling fluid fed to the inlet (3) of the nozzle (2) is set in such a way that the nozzle (2) firmly sucks against the surface (1), which is to be cooled, in accordance with the Bernoulli principle.
2. Method according to claim 1, wherein the spacing (d) of the outlet (5) from the surface to the cooled is variable substantially in a direction (8) perpendicular to the surface to be cooled.
3. Method according to claim 1 or 2, wherein the nozzle (2) is mounted to be at least partly sliding in a guide (7).
4. Method according to any one of the preceding claims, wherein the nozzle (2) is mounted to be biased substantially perpendicularly to the surface to be cooled.
5. Method according to any one of the preceding claims, wherein the cross-section (A) of the outlet (5) is formed to be substantially rotationally symmetrical in a plane lying parallel with the surface to be cooled or, alternatively, is formed to be elongate, particularly substantially elliptical, to counteract the influence of a surface to be cooled which is moved.
6. Method according to any one of the preceding claims, wherein the nozzle (2) is subjected to oscillatory movement substantially parallel to the surface (1) to be cooled.
7. Method according to any one of the preceding claims, wherein several nozzles (2) or rows of nozzles (2) are subjected to oscillatory movements substantially parallel to the surface (1) to be cooled and the oscillation of adjacent nozzles (2) or nozzle rows (2) takes place at least in part in the same sense or in opposite sense.
8. Method according to any one of the preceding claims, wherein the nozzle (2) has between the inlet (3) and the outlet (5) a guide region (9) in which the coolant is guided substantially in a direction (S) perpendicular to the surface (1) to be cooled from the inlet (3) to the outlet (5) and is laterally enclosed by this.
9. Method according to any one of the preceding claims, wherein the cross-section (A) of the outlet (5) widens, preferably constantly, in downstream direction.
10. Method according to any one of the preceding claims, wherein the setting of the volume flow comprises setting of the flow speed thereof and/or the pressure thereof.
11. Method according to any one of the preceding claims, wherein the variable spacing (d) between the outlet (5) and the surface (1) to be cooled is kept by a limiting element (11) to be larger than 0.09 millimetres and preferably larger than 0.5 millimetres independently of the volume flow (V) provided.
12. Method according to any one of the preceding claims, wherein the supplied volume flow (V) is formed by a cooling liquid.
13. Method according to any one of the preceding claims, wherein the outlet (5) of the nozzle (2) is arranged opposite the surface of a roll or opposite the surface of a metal strip (1) between two roll stands of a roll train.
14. Method according to any one of the preceding claims, wherein several nozzles (2) are arranged in grid-like form in a plane opposite the surface (1) to be cooled or several nozzles (2) are arranged in each of a plurality of mutually adjacent rows opposite the surface to be cooled.
15. A cooling device (10) for cooling a surface of cast material, rolling stock (1) or a roll and for carrying out the method according to any one of the preceding claims, comprising:

    at least one nozzle (2) comprising an inlet (3) with a first clear cross-section (E) and an outlet (5), which Is opposite the surface (1) to be cooled, with a second clear cross-section (A) greater than the first cross-section (E), wherein the cooling device (10) is additionally constructed so that the spacing (d), which is perpendicular to the surface to be cooled, between the outlet (5) of the nozzle (2) and the surface to be cooled is variable between 0.1 millimetres and 5 millimetres, preferably between 0.5 millimetres and 2 millimetres.
16. A rolling device for the rolling of rolling stock, comprising at least one cooling device (10) according to claim 15,
    wherein the rolling device comprises at least one roll with a roll surface to be cooled and the outlet (5) of the nozzle (2) for cooling is directed towards the roll surface; or
    wherein the rolling device comprises at least two mutually adjacent roll stands for rolling a metal strip (1) and the cooling device (10) is arranged between the two roll stands for cooling the surface of the metal strip (1) present between the two roll stands.

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