DE102022210993A1 - Supporting strand guide for a continuous casting plant, and method for cooling a cast strand - Google Patents

Abstract

The invention relates to a supporting strand guide (100) for a continuous casting plant, each of which comprises a plurality of cooling zones (102), wherein in each cooling zone (102) at least one row (105) of fluid outlets (104) extending transversely to the casting direction (G) of the continuous casting plant (10) is provided for discharging a cooling liquid in the direction of a cast strand (20). At least one cooling zone (102) of the supporting strand guide (100) has at least two subcooling zones (106) with associated rows (105) of fluid outlets (104) each extending transversely to the casting direction (G) of the continuous casting plant (10), wherein the subcooling zones (106) - seen in the casting direction (G) of the continuous casting plant (10) - are arranged one after the other and have a different cooling capacity compared to one another in that a different amount of cooling medium can be discharged in the direction of the cast strand (20) from the fluid outlets (104) assigned to the respective subcooling zones (106).

Description

The invention relates to a supporting strand guide according to the preamble of claim 1, and to a method for cooling a cast strand moved in a supporting strand guide of a continuous casting plant according to the preamble of claim 12.

When operating continuous casting plants, it is state of the art to cool the cast strand after it has left the mold in the so-called secondary cooling of a supporting strand guide of the plant until the cast strand has completely solidified. This is the case, for example, for EN 10 2018 220 386 A1 This cooling process plays an important role in the resulting quality of the cast strand and the products produced from it. Complete solidification of the cast strand should be achieved within the cooling segments of the supporting strand guide, which support the cast strand with the core still liquid.

The operation of the secondary cooling is usually carried out with a cooling medium in the form of spray or cooling water or by means of a dual-fluid cooling system, namely in the form of spray or cooling water and compressed air, whereby the amount of the cooling medium or the mixture of cooling water and compressed air that is applied to the surfaces of the cast strand is adjusted by specifying spray plans or target temperature curves.

The supporting strand guide of a continuous casting plant usually consists of several segments that are arranged on both sides of a cast strand moving in a casting direction or above and below it. With regard to such segments, it is known that a cooling zone of the supporting strand guide consists of one or more such segments. In other words, several such segments of a supporting strand guide can be combined to form a cooling zone. In a cooling zone, the same control circuit acts in the middle of the strand to apply a cooling medium to the cast strand, preferably in the form of water or two cooling media in the form of spray or cooling water and compressed air (also known as dual-fluid cooling), with the same specific amount of cooling medium being applied to the cast strand in the entire cooling zone.

There are usually several different cooling zones along the supporting strand guide of a continuous casting plant, each with a different cooling capacity, which results in different exposure to cooling medium or water. In other words, with a conventional supporting strand guide, the division into cooling zones for a cast strand that is moved through these cooling zones in the casting direction results in relatively large steps or "jumps" in the exposure to cooling medium or water between two adjacent cooling zones.

Another disadvantage of a conventional supporting strand guide and its cooling zones is that the fluid outlets or spray nozzles, which are each provided in a cooling zone, are all supplied with the same amount of cooling medium or water because they are each connected to the same control circuit for supplying cooling medium or water. With temperature control, the total amount of cooling medium or water in a respective cooling zone is varied in order to reach a predetermined target temperature. As a result, it can happen that parts of the cast strand within a cooling zone are supplied with amounts of water that are not optimal for these strand sections due to the process conditions.

10 shows a simplified top view of a portion of a supporting strand guide according to the prior art, with a cooling zone 102. In this cooling zone, a plurality of rows of fluid outlets 104 or nozzles are provided transversely to the casting direction G, each of which is arranged between adjacent support rollers 101 (shown here only in a simplified manner as a dashed line). The fluid outlets 104 or nozzles are generally all connected to a common water supply or a corresponding control circuit for the supply of a cooling medium or water. This means that when the temperature is controlled, the entire amount of water in this cooling zone is varied uniformly in order to achieve a predetermined target temperature. However, this can lead to the disadvantages already mentioned above.

A corresponding temperature profile of a conventional supporting strand guide according to 10 is in the 8th illustrated - from this it can be seen that in particular the temperature profile 132 of the average shell temperature of the cast strand and the temperature profile 134 of the middle of the top of the cast strand are each unsteady or have "jumps" depending on the distance from the casting level, both within the respective cooling zones and in particular in the border area between adjacent cooling zones. This is due, among other things, to the above-mentioned relatively large jumps in the application of cooling medium or water between two adjacent cooling zones.

If the specific water quantities in a cooling zone are significantly lower than those in the - If the temperatures are lower than the previous cooling zone - in the casting direction - for example by at least 50 l/min/m ² , preferably by at least 100 l/min/m ² , the cooling effect drops significantly and reheating occurs in a still liquid strand core. This can be seen in the temperature diagram of 8th for the temperature profile of curve 134 during temperature control at a distance of about 7 meters from the casting surface. This wave formation in the surface temperature can result in reheating in the strand shell. Since the material density decreases with increasing temperature, expansion occurs. This expansion can lead to internal cracks in the cast strand and the metallic products formed from it, particularly in the case of additional curvature changes such as in the bending or straightening area.

Accordingly, the invention is based on the object of achieving a more uniform temperature control for a cast strand during continuous casting and thus an improvement in the internal quality of a cast strand.

The above-mentioned object is achieved by a supporting strand guide with the features of claim 1 and by a method for cooling a cast strand specified with the features of claim 12. Advantageous developments of the invention are defined in the dependent claims.

The invention provides a supporting strand guide that can be used in a continuous casting plant and can also be retrofitted for this purpose if necessary. Such a supporting strand guide comprises a plurality of cooling zones, wherein in each cooling zone at least one row of fluid outlets extending transversely to the casting direction of the continuous casting plant is provided for discharging a cooling medium, preferably water, in the direction of a cast strand. At least one cooling zone of the supporting strand guide, preferably a plurality of the cooling zones or all cooling zones, each has at least two subcooling zones with associated rows of fluid outlets each extending transversely to the casting direction of the continuous casting plant, wherein the subcooling zones - seen in the casting direction of the continuous casting plant - are arranged one after the other and have a different cooling capacity compared to one another in that a different amount of cooling medium can be discharged in the direction of the cast strand from the fluid outlets assigned to the respective subcooling zones.

According to a preferred embodiment of the strand guide according to the invention, it is provided that the subcooling zones within a cooling zone - seen in the casting direction of the continuous casting plant - have a continuously decreasing cooling capacity compared to one another.

In the same way, the invention provides a method for cooling a cast strand moved in a supporting strand guide of a continuous casting plant. In this method, the supporting strand guide has a plurality of cooling zones which - viewed in the casting direction of the continuous casting plant - are arranged one after the other, with at least one row of fluid outlets extending transversely to the casting direction of the continuous casting plant being provided in each cooling zone for discharging at least one cooling medium, preferably water or a two-component mixture consisting of cooling water and compressed air, in the direction of the cast strand. The cast strand passes through at least two subcooling zones provided in at least one cooling zone of the supporting strand guide, with these subcooling zones being arranged one after the other - viewed in the casting direction of the continuous casting plant - and having a different cooling capacity compared to one another, in that a different amount of cooling medium is discharged in the direction of the cast strand from fluid outlets assigned to the respective subcooling zones.

The present invention further relates to a continuous casting plant for producing a metallic product, comprising a mold and a supporting strand guide which - viewed in the casting direction of the continuous casting plant - is arranged downstream of the mold. In this case, the supporting strand guide is designed in the form of a strand guide as explained above.

The invention is based on the essential finding that, at least within a certain cooling zone of a supporting strand guide, if this is equipped with at least two subcooling zones, a more uniform temperature control for a cast strand is possible compared to the prior art, in which - seen in the casting direction of the continuous casting plant - there are smaller temperature differences or jumps. Mutatis mutandis, this also applies to adjacent cooling zones of a supporting strand guide if these are each equipped with at least two subcooling zones. In this case, it is possible that the temperature jumps or differences between two adjacent cooling zones are smaller and in this respect a more uniform temperature control is achieved for a cast strand if it passes through the supporting strand guide according to the invention in the casting direction of an associated continuous casting plant.

In an advantageous development of the invention, several rows of fluid outlets can be arranged within a subcooling zone and thus this subcooling zone, whereby these rows of fluid outlets each extend transversely to the casting direction of the continuous casting plant and - viewed in the casting direction of the continuous casting plant - are arranged one after the other and parallel to one another. Alternatively, it is also possible for a subcooling zone in a cooling zone to be formed by only a single row of fluid outlets which extend transversely to the casting direction of the continuous casting plant.

In an advantageous development of the invention, the fluid outlets of the individual subcooling zones can each be connected to different control circuits for cooling liquid. In this case, it is also expedient if a process computer is provided which is equipped with a calculation model in terms of programming and is connected to the individual control circuits for the subcooling zones in terms of signals. This then makes it possible for changing process data of a continuous casting process to be recorded by the process computer and for the individual control circuits for the subcooling zones to be controlled on the basis of these changed process data using the calculation model in order to thereby achieve a predetermined amount of cooling liquid being applied to the cast product in the individual subcooling zones.

In an advantageous development, for at least one row of fluid outlets extending transversely to the casting direction of the continuous casting plant and arranged in a subcooling zone, it is provided that this row has a central region and adjacent edge regions, with the central region on the one hand and the two edge regions on the other hand each being connected to different control circuits for the supply of cooling medium. This is done for the purpose of allowing the cooling performance in the two edge regions to be adjusted in a different way compared to the cooling performance in the central region, namely by appropriately controlling the fluid outlets or supplying cooling medium. This means that in each subcooling zone at least one row of fluid outlets, preferably several such rows or even all rows of a specific subcooling zone, is or are divided transversely to the casting direction (i.e. across the strand width) into a central region and adjacent edge regions, with this central region on the one hand and the adjacent edge regions of such a row of fluid outlets on the other hand each being supplied with cooling medium by different control circuits.

It is also preferably possible for an edge region of a series of fluid outlets to be divided into at least two zones, each of which is connected to different control circuits for the supply of cooling fluid. If required, such an edge region can also be divided into more than two zones, for example into three, four or five zones, in order to achieve a differentiated supply of cooling fluid (i.e. in different quantities) in the individual zones of the edge region.

In an advantageous development of the method according to the invention, it is provided that the subcooling zones within a cooling zone - seen in the casting direction of the continuous casting plant - have a continuously decreasing cooling capacity compared to one another. This meets the requirement that in a continuous casting plant the specific water loading decreases from the plant head (= mold) to the plant end, whereby according to the invention the temperature differences within a cooling zone are less great thanks to the division into at least two subcooling zones.

In an advantageous development of the method according to the invention, it can be provided that the fluid outlets in a first subcooling zone and the fluid outlets in the second subcooling zone, which - seen in the casting direction of the continuous casting plant - is arranged downstream of the first subcooling zone, are each connected to different control circuits of cooling medium, so that a larger amount of cooling medium (specifically) is discharged from the fluid outlets of the first subcooling zone to cool the cast strand compared to the second subcooling zone. In this case, according to a further advantageous development of the method according to the invention, it is expedient that a process computer is provided which is equipped with a calculation model in terms of programming and is connected to the individual control circuits for the subcooling zones in terms of signals, whereby changing process data of a continuous casting process are recorded by the process computer and the individual control circuits for the subcooling zones are controlled on the basis of these changed process data by means of the calculation model in order to achieve a predetermined amount of cooling medium being applied to the cast product in the individual subcooling zones.

According to an advantageous development of the method according to the invention, it can be provided that the changing process data of the continuous casting process are selected from the group consisting of material change, casting temperature, casting speed and an age of the cast strand derived therefrom in a certain cooling zone, strand geometry and/or mold cooling.

• • Werkstoffwechsel,
• • Änderung der Gießtemperatur,
• • Änderung der Strangbreite oder Strangdicke, und/oder
• • Änderung der Kokillenkühlung (Gießspiegel, Kokillenwasser, Gießpulver).

Using the calculation model mentioned above, it is possible to calculate the Cast strand, which is moved along the supporting strand guide, to track or trace positions at which process conditions have changed during the production of the cast strand, e.g. by:

• • Material change,
• • Change of casting temperature,
• • Change in strand width or strand thickness, and/or
• • Change in the mold cooling (mold level, mold water, molding powder).

Such tracking enables improved and more targeted water application to the cast strand in a cooling zone, which, as explained, is equipped with at least two subcooling zones. In this context, it should be noted that the water quantities are specified per cooling zone in the spray plan as before. Nevertheless, the cooling zones can be divided into subcooling zones with their own control valves - up to and including individual switching of a row of nozzles. In this case, these subcooling zones can now be switched and controlled separately, depending on the position of the changed process values.

• • Automotive Stählen,
• • hochlegierten Stählen, und/oder
• • Sonderstählen

The present invention leads, among other things, to the advantage of a higher product quality compared to the prior art, in particular in:

• • Automotive steels,
• • high-alloy steels, and/or
• • Special steels

This means that the present invention is particularly used in the production of high-quality grades.

• 1 eine schematisch vereinfachte Seitenansicht einer Stranggießanlage, mit der ein Verfahren nach der vorliegenden Erfindung durchführbar ist und die mit einer erfindungsgemäßen stützenden Strangführung ausgestattet ist,
• 2 eine vereinfachte Draufsicht auf eine Kühlzone gemäß einer ersten Ausführungsform der Erfindung, als Teilbereich einer stützenden Strangführung, die Teil der Stranggießanlage von 1 sein kann,
• 3 eine vereinfachte Draufsicht auf eine Kühlzone gemäß einer zweiten Ausführungsform der Erfindung, als Teilbereich einer stützenden Strangführung, die Teil der Stranggießanlage von 1 sein kann,
• 4 eine prinzipiell vereinfachte Draufsicht auf eine Reihe von Fluidauslässen, die Teil einer stützenden Strangführung von 2 oder 3 ist,
• 5 eine prinzipiell vereinfachte Draufsicht auf eine Kühlzone, die eine Variante zur ersten Ausführungsform der Kühlzone von 2 darstellt,
• 6 eine prinzipiell vereinfachte Draufsicht auf eine Kühlzone, die eine weitere Variante zur ersten Ausführungsform der Kühlzone von 2 darstellt,
• 7 ein Diagramm für Temperaturverläufe von verschiedenen Bereichen eines Gießstrangs als Funktion eines Abstands vom Gießspiegel, und
• 9 ein Diagramm für Temperaturverläufe von verschiedenen Bereichen eines Gießstrangs als Funktion eines Abstands vom Gießspiegel.

Embodiments of the invention are described in detail below with reference to a schematically simplified drawing. They show:

• 1 a schematically simplified side view of a continuous casting plant with which a method according to the present invention can be carried out and which is equipped with a supporting strand guide according to the invention,
• 2 a simplified plan view of a cooling zone according to a first embodiment of the invention, as a portion of a supporting strand guide, which is part of the continuous casting plant of 1 can be,
• 3 a simplified plan view of a cooling zone according to a second embodiment of the invention, as a portion of a supporting strand guide, which is part of the continuous casting plant of 1 can be,
• 4 a basically simplified plan view of a series of fluid outlets that are part of a supporting strand guide of 2 or 3 is,
• 5 a basically simplified plan view of a cooling zone, which is a variant of the first embodiment of the cooling zone of 2 represents,
• 6 a basically simplified plan view of a cooling zone, which is a further variant of the first embodiment of the cooling zone of 2 represents,
• 7 a diagram for temperature profiles of different areas of a cast strand as a function of a distance from the casting level, and
• 9 a diagram showing temperature profiles of different areas of a cast strand as a function of a distance from the mold level.

Below, with reference to the 1 to 7 and 9 preferred embodiments for a supporting strand guide 100 and a method for cooling a cast strand moved in such a supporting strand guide of a continuous casting plant are explained, with which a more uniform cooling of the cast strand can be achieved. Identical features in the drawing are each provided with the same reference numerals. At this point, it is specifically pointed out that the drawing is only simplified and in particular is shown without a scale.

1 shows, in principle, a simplified side view of a continuous casting plant 10 according to the present invention, with which the target temperatures of associated cooling segments 12 of the associated supporting strand guide 100 can be set.

The continuous casting plant 10 according to 1 comprises a mold 15 which has a vertical outlet downwards. Liquid metal is poured into the mold 15 up to a casting level 16. The continuous casting plant 10 comprises a supporting strand guide 100 in the area of a secondary cooling 18, whereby a cast or metal strand 20 then exits downwards from the mold 15 and is moved or transported along the strand guide 100 in a conveying direction F. The individual cooling segments 12 are combined to form the supporting strand guide 100 and ensure the application of at least one cooling medium, in particular in the form of water, e.g. through spray nozzles, to both sides of the metal strand 20, whereby the metal strand 20 is cooled in a targeted manner.

In connection with the discharge of at least one cooling medium from the individual cooling segments 12, It should be noted that either water or a two-component mixture consisting of cooling water and compressed air is suitable for this purpose. The latter case, ie the use of a two-component mixture consisting of cooling water and compressed air, is also known as "two-component cooling". If the following explanation refers to the application of a cooling medium or liquid, this always also means the application of a two-component mixture consisting of cooling water and compressed air in the sense of the present invention.

The supporting strand guide 100 with its individual cooling segments 12 is arranged directly downstream of the mold 15 or downstream thereof, as seen in the conveying direction F of the metal strand 20. Accordingly, the metal strand 20, immediately after it has exited downwards from the mold 15, then runs into the downstream supporting strand guide 100.

The cooling segments 12 are each connected to control circuits 110 for the supply of cooling fluid and are each fed with cooling fluid (or a two-component mixture consisting of cooling water and compressed air, as explained above) via lines (not shown) and are each equipped with spray nozzles. Accordingly, it is possible to apply cooling fluid (or the said two-component mixture) to the surfaces of the metal strand 20, namely on its top and/or bottom, through the spray nozzles of the individual cooling segments 12.

According to the invention, a process computer 121 is also provided, which is connected to the cooling segments 12 of the supporting strand guide 100 via a signal path 23. This signal path 23 can be wired or wireless, e.g. via a radio link or the like. In this case, the process computer 121 can also be connected to individual control circuits of cooling zones and subcooling zones located therein for supplying a cooling liquid. The importance of these cooling zones and subcooling zones is explained elsewhere below.

The process computer 121 is connected to a data storage 24 in which the required process data for the continuous casting plant 10 are stored. In this respect, this data storage 24 forms a database. Via an interface (not shown) it is possible to enter or read individual process data PD into the data storage 24. This input option is provided in the 1 symbolized by the arrow with “PD”.

The continuous casting plant 10 is equipped with at least one temperature sensor 26, or a plurality of such sensors, which is or are arranged adjacent to the supporting strand guide 100. The temperature of the metal strand 20 can be determined by means of the sensor 26 or a plurality of such sensors in order to compare, for example, the previously calculated temperature of the metal strand 20 with the measurement. The temperature data of the sensor or sensors 26 are first fed to a data acquisition unit 28 and from there fed to the control or regulating unit 22.

In deviation from the representation of 1 It is also possible for the present invention that a temperature sensor 26 is arranged in the course of the supporting strand guide 100 between two adjacent cooling segments 12, and/or in the region of a cooling segment 12 or adjacent thereto.

The data memory 24 stores variables or parameters on the basis of which target temperatures can be set or determined for the individual cooling segments 12 along the strand guide 100. These variables are, for example, dependent on a specific material or a specific group of materials from which the metal strand 20 is manufactured, and in any case independent of a specific continuous casting plant.

2 shows a simplified plan view of a portion of the supporting strand guide 100 and an associated cooling zone 102 according to a first embodiment of the invention. Here, the conveying direction F or casting direction G, in which a cast strand 20 is moved along the supporting strand guide 100, is symbolized by a corresponding arrow "F/G" (in the 2 running from left to right).

The support rollers 101, which are provided in the supporting strand guide 100 and each run transversely to the casting direction, are shown in the illustration of 2 simplified and shown only as dashed lines.

Between the individual support rollers 101, a plurality of fluid outlets 104 are provided, which in the illustration of 2 are each symbolized in simplified form with an "x". During operation of the continuous casting plant 10, a cooling medium (a cooling liquid or a two-component mixture consisting of cooling water and compressed air, as explained above) is discharged from these fluid outlets 104 in a targeted manner in the direction of the cast strand 20.

In accordance with an alignment of the individual support rollers 101 transverse to the casting direction G, the said fluid outlets are also 104, which are each provided between the support rollers 101, each arranged transversely to the casting direction G and in the form of a row 105. This means that the fluid outlets 104 in the cooling zone 102 are each arranged in the form of individual rows 105.

The individual fluid outlets 104 can each be equipped with nozzles or spray nozzles (not shown), by means of which the discharge of cooling liquid in the direction of the cast strand is specifically improved.

The effective range of the individual fluid outlets 104, which can be equipped with nozzles as explained, is shown in the illustration of 2 with narrow rectangles that border on the center point "x" of these fluid outlets 104, and are designated with "W". In this regard, it should be emphasized that in a row of fluid outlets 104, the effective areas W of adjacent or neighboring fluid outlets 104 can overlap.

In the first embodiment of a cooling zone 102 according to 2 Two subcooling zones 106 are provided in this cooling zone, namely in the form of a first subcooling zone 106.1 and a second subcooling zone 106.2. Viewed in the pouring direction G, the first subcooling zone 106.1 is located upstream or in front of the second subcooling zone 106.2. Furthermore, it should be emphasized for this first embodiment of the cooling zone 102 that several rows 105 of fluid outlets 104 are each combined to form a subcooling zone 106. This applies equally to the first subcooling zone 106.1 and to the second subcooling zone 106.2.

Conveniently, in the first embodiment of the cooling zone 102 according to 2 It is provided that the first subcooling zone 106.1 has a greater cooling capacity than the second subcooling zone 106.2. This can be achieved, for example, by the fluid outlets 104 or the associated nozzles in the first subcooling zone 106.1 having a greater capacity than the nozzles in the second subcooling zone 106.2, so that a greater amount of cooling medium can be discharged from the nozzles in the first subcooling zone 106.1 than in the second subcooling zone 106.2.

With regard to the first subcooling zone 106.1 and the second subcooling zone 106.2, it is specifically pointed out at this point that these two subcooling zones and the individual rows 105 provided therein can be connected together at fluid outlets 104, i.e. they are all connected to a common water supply or a control circuit provided for this purpose.

In addition or as an alternative, in view of the said different cooling performance of the two subcooling zones 106.1, 106.2, it can be provided that the first and second subcooling zones 106.1, 106.2 are each connected to different control circuits for the supply of cooling liquid. This can also ensure that the amount of water supplied to the fluid outlets 104 in the first subcooling zone 106.1 is greater than the amount of water for the second subcooling zone 106.2. This makes it possible to reduce the water exposure of the cast strand 20 in the casting direction G as desired within the cooling zone 102, which as explained consists of the two subcooling zones 106.1, 106.2.

3 shows a simplified plan view of a portion of the supporting strand guide 100 and an associated cooling zone 102 according to a second embodiment of the invention. In contrast to the first embodiment of 2 The cooling zone 102 shown here consists of a plurality of individual subcooling zones 106, each of which is formed from a single row 105 of fluid outlets 104. In the same way as already described for 2 As explained, these rows 105 of fluid outlets 104 each extend transversely to the casting direction G of the continuous casting plant 10. According to the invention, these fluid outlets 104 are supplied with cooling liquid in such a way that the individual subcooling zones 106 (as explained: each formed from a single row 105 of fluid outlets 104) are each connected to separate control circuits of the water supply. This is expediently done in that the individual rows 105 of fluid outlets 104 or nozzles and the subcooling zones 106 formed thereby have their own control valves.

With respect to the cooling zone 102 according to 3 It is understood that the fluid outlets 104 of the individual subcooling zones 106, in the same way as in the cooling zone of 2 , each of which can be equipped with nozzles through which the discharge of a cooling liquid in the direction of the cast strand 20 is specifically improved.

According to the present invention, an operation of the continuous casting plant 10 provided with a supporting strand guide 100 according to the 2 or the 3 and thus an associated method for cooling the cast strand 20, which is moved in the supporting strand guide 100, in such a way that the subcooling zones 106, into which a cooling zone 102 is divided, are supplied with cooling liquid, with - in the casting direction G - each with a decreasing cooling capacity. This means that the subcooling zones 106 within a cooling zone 102 - seen in the casting direction G of the continuous casting plant 10 - have a continuously decreasing cooling capacity compared to one another.

As already explained above, it can be provided for a cooling zone 102 that the subcooling zones 106 provided therein with their associated fluid outlets 104 are each connected to different control circuits for the supply of a cooling liquid. This is equally possible for a plurality of cooling zones 102 that are provided along the casting direction G of the continuous casting plant within the supporting strand guide 100 and are each divided into at least two subcooling zones 106. In any case, it can be provided for a method according to the invention that changing process data of the continuous casting process are recorded by the process computer 121 and the individual control circuits 110 for the subcooling zones 106 are controlled on the basis of these changed process data by means of the calculation model 121 in order to thereby achieve a loading of the cast strand 20 with a predetermined amount of cooling liquid in the individual subcooling zones 106.

• • Werkstoffwechsel.
• • Änderung der Gießtemperatur,
• • Änderung der Strangbreite oder Strangdicke, und/oder
• • Änderung der Kokillenkühlung (Gießspiegel, Kokillenwasser, Gießpulver).

The process computer 121 (cf. 1 ) is equipped with a calculation model 122 in terms of programming. This process computer 121 thus makes it possible for the current values for the process parameters to be saved in the calculation model 122 when the cast strand 20 exits the mold 15 and to be assigned to a point on the cast strand 20 currently leaving the mold. These values now run through the continuous casting system 10 and its supporting strand guide 100 at the casting speed, whereby each calculation point in the casting direction has a separate value vector. In other words, the calculation model 122 can be used to track or trace the position at which the process conditions have changed, e.g. by:

• • Material change.
• • Change of casting temperature,
• • Change in strand width or strand thickness, and/or
• • Change in the mold cooling (mold level, mold water, molding powder).

Such tracking enables improved and more targeted water application in or along the supporting strand guide 102 and its associated cooling zones 102 or subcooling zones 106.

In the spray plan, the water quantities are specified as before for each cooling zone 102. As already explained above, the cooling zones 102 can be divided into subcooling zones 106 with their own control valves - up to an individual switching of a row 105 of fluid outlets 104 or nozzles. These subcooling zones 106 can now be switched and controlled separately, depending on the position of the changed process values.

Below, with reference to the 4-6 Variants of a cooling zone 102 according to the embodiments of 2 and 3 shown and explained. In the 4-6 The pouring direction is also marked with “G” and symbolized by a corresponding arrow.

4 shows a basically simplified plan view of a row 105 of fluid outlets 104 which are arranged in a subcooling zone 106 (or 106.1 and/or 106.2) of a cooling zone 102 of the supporting strand guide 100 according to the embodiment of 2 or 3 In such a row 105, the fluid outlets 104 contained therein are arranged in the same way as in 2 or 3 merely symbolized by an “x”.

For the series 105 according to 4 It should be emphasized that a central region M is provided in which, for example, two fluid outlets 104 or associated nozzles are arranged. Adjacent to this central region M, i.e. to the left and right of it, there is an edge region R of the row 105, with a fluid outlet 104 being provided in each of these edge regions R. In simple terms, the sum of a length of the central region M and the two edge regions R, seen transversely to the casting direction G, can correspond to a width B of the cast strand 20. This is shown in the plan view of 4 indicated accordingly by a curly bracket.

Regarding the supply of cooling medium to the fluid outlets located in row 105 of 4 are provided, it is specially emphasized at this point that on the one hand the central zone M and on the other hand the two edge zones R are each connected to different control circuits for the supply of cooling medium.

This is done so that the cooling capacity in the two edge regions R can be selected differently or set to a different value compared to the central region M. In concrete terms, this can be achieved by supplying a different amount of cooling medium to the fluid outlets 104 provided in the edge regions R of the row 105 than the fluid outlets 104 in the central region M of said row 105.

With respect to a row 105 of fluid outlets according to the embodiment of 4 It should be emphasized that according to the invention, at least two different control circuits for the supply of cooling medium are provided over the width B of the cast strand 20, namely on the one hand a control circuit for the central region M of the row 105, and on the other hand a further control circuit for the two edge regions R of the row 105. This is explained below with reference to the 5 shown and explained again.

5 shows a simplified plan view of a variant of the cooling zone 102 according to the first embodiment of 2 , whereby in this variant of 5 Now, in both the first subcooling zone 106.1 and the second subcooling zone 106.2, at least one row 105 of fluid outlets, as shown in the 4 Preferably, several rows 105 of fluid outlets 105 are provided in the respective subcooling zones 106.1, 106.2 as shown in 4 shown. Further preferably, all rows 105 of a respective subcooling zone 106.1, 106.2 are as in 4 In any case, the present invention is characterized for the variant according to 5 in that the fluid outlets 104 contained in the central region M of the first subcooling zone 106.1 are connected to a control circuit 107.1, whereby the fluid outlets 104 contained in the adjacent lateral edge regions R are each connected to another control circuit 108.1 in order to be supplied with cooling medium. Mutatis mutandis, this also applies to the second subcooling zone 106.2, in which the fluid outlets 104 of a respective

Row 105 in the central region M is connected to a control circuit 107.2, and the fluid outlets 104 in the two lateral edge regions R are each connected to another control circuit 108.2 in order to be supplied with cooling medium.

Regarding the cooling capacity of the two subcooling zones 106.1, 106.2 of 5 The same functional principle applies as already 2 explained: The amount of water or cooling fluid that is supplied to the fluid outlets 104 in the first subcooling zone 106.1 is greater than the amount of cooling fluid for the second subcooling zone 106.2. For example, a larger amount of cooling fluid is supplied by the control circuit 107.1, to which the fluid outlets 104 in the central region M of the first subcooling zone 106.1 are connected, than by the control circuit 107.2, to which the fluid outlets 104 in the central region M of the second subcooling zone 106.2 are connected. Mutatis mutandis, this also applies with regard to the two control circuits 108.1 (through which the fluid outlets in the edge regions R of the first subcooling zone 106.1 are supplied with cooling fluid) and 108.2 (through which the fluid outlets in the edge regions R of the second subcooling zone 106.2 are supplied with cooling fluid). As explained, the exposure of the cast strand 20 to cooling fluid - seen in the casting direction G - can thus be reduced within the cooling zone 102 along its subcooling zones 106.1, 106.2.

6 shows a simplified plan view of another variant of the cooling zone 102 according to the first embodiment of 2 Here too, it can be provided that in a respective subcooling zone 106.1, 106.2 at least one row 105 of fluid outlets 104 is included, which are connected to several different control circuits for the supply of cooling fluid across the strand width B. Preferably, in a respective subcooling zone 106.1, 106.2, there are several such rows 105 of fluid outlets, or even all rows 105 that are included in a subcooling zone 106 (or 106.1, 106.2).

In contrast to the variant of 5 are in the variant of 6 the respective edge regions R, which are provided for at least one row 105 of fluid outlets 104 in preferably each of the two subcooling zones 106.1, 106.2, are divided into two zones, namely a first zone Z1, which directly adjoins the central region M, and a second zone Z2, which then adjoins the first zone Z1 and borders on a longitudinal side edge of a cast strand 20.

For the variant according to 6 It is pointed out separately that each of the first and second zones Z1, Z2, from which a respective edge region R is formed, is connected to a separate control circuit for the supply of cooling fluid. 6 In the example shown, this means that the first zones Z1, which are located within the first subcooling zone 106.1, are connected to a control circuit 108.1, whereby the second zones Z2, which are located within the first subcooling zone 106.1, are connected to a control circuit 109.1 for the supply of cooling fluid. Mutatis mutandis, this also applies to the first and second zones Z1, Z2, which are each contained in the second subcooling zone 106.2. Specifically, the first zone Z1 (within the second subcooling zone 106.2) is connected to a control circuit 108.2, whereby the second zone Z2 (within the second subcooling zone 106.2) is connected to a control circuit 109.2.

Analogous to the variant of 5 also applies to the variant of a cooling zone 102 of 6 that within a respective subcooling zone 106.1, 106.2 using the zones Z1, Z2 it is possible to set the cooling capacity in an edge area R to a different value than in the central area M. In addition, using the zones Z1, Z2 in the variant according to 6 It is also possible to set a different cooling capacity within a respective edge region R by discharging a different amount of cooling fluid in the direction of the cast strand 20 from the fluid outlets arranged there.

The reduction of the cooling capacity of a cooling zone 102 according to the variant of 6 along the casting direction G, ie from the first subcooling zone 106.1 to the second subcooling zone, corresponds in the same way and thus unchanged to the functioning of 5 , so that reference may be made to it in order to avoid repetition. In this context, with regard to the provisions of the 6 and 6 shown hatchings, which are selected for the respective areas of a subcooling zone 106.1, 106.2, which are each located in the same place across the strand width B, it is specifically pointed out that the thickness of the hatching - viewed along the casting direction G - is selected to decrease. For example, the hatching of the central area M, which is connected to the control circuit 107.2 and is located within the second subcooling zone 106.2, is selected to be thinner than the hatching of the central area M, which is connected to the control circuit 107.1 and is located within the first subcooling zone 106.1. This shows that the cooling capacity in the central area M of the second subcooling zone 106.2 is set lower than in comparison to the central area of the first subcooling zone 106.1. This also applies in the same way to the edge areas R (cf. 5 ) and the zones Z1, Z2 contained therein (cf. 6 ) of the second subcooling zone 106.2 compared to those of the first subcooling zone 106.1.

With regard to the variants of a cooling zone 102 according to the 5 and 6 It is pointed out separately that all width control loops, ie the control loops to which the fluid outlets 104 of at least one row 105 in the individual areas M and R or the zones Z1, Z2 are connected, are divided or subdivided into at least two subcooling zones 106.1, 106.2, namely either by different control loops and/or by using different types of nozzles, seen in the pouring direction G. As already explained above, this can also be applied to a cooling zone 102 according to the second embodiment of 3 .

With regard to the variants of a cooling zone 102 according to 5 and 6 the control loops 107.1, 107.2, 108.1, 108.2, 109.1 and 109.2 explained here may (at least partially) be the control loops 110, which are described in the 1 and with which the cooling segments 12 of the supporting strand guide 100 are supplied with cooling fluid.

The diagram of 7 clarifies the current position of a higher casting temperature, which has been established due to a change in material, in relation to the temperature profile 130 of the core of the cast strand 20. As in the 5 indicated by an arrow, this "jump point" of the temperature change is currently at a value of about 6.5 meters from the casting level. Knowing this jump point or temperature change, which now "wanders" through the supporting strand guide 100 when the cast strand moves in the casting direction G or conveying direction F, the individual cooling zones 102 and the associated subcooling zones 106 can be suitably controlled in order to discharge a predetermined desired amount of cooling liquid through the fluid outlets 106 in the direction of the cast strand 20.

An advantageous effect of the inventive division of a cooling zone 102 into individual subcooling zones 106 is illustrated by a comparison of the 8th and 9 .

As already explained in the introduction, the 8th for a conventional supporting strand guide, the temperature profile 103 for the core of the cast strand, the temperature profile 132 of the average shell temperature of the cast strand 20 and the temperature profile 134 of the middle of the top of the cast strand. In the 8th Individual cooling zones 102 are provided at increasing distances from the mold level, the boundary areas of which are symbolized here by solid vertical lines.

In comparison, the 9 a diagram for temperature profiles of different areas of a cast strand as a function of a distance from the casting level, namely in relation to a supporting strand guide 100 according to the invention. Here, the respective cooling zones 102 are each divided into individual subcooling zones 106, the boundary areas of which in 9 are each symbolized by a vertical dotted line. A comparison of the temperature curves 132 and 134 of 9 with those of 8th clearly shows that a uniform progression along a distance from the casting level is established, particularly with regard to the average shell temperature and the center of the top of the casting strand 20. This is largely due to the fact that the cooling zones 102 are divided into subcooling zones 106, thanks to which a finely graduated application of cooling liquid to the casting strand 20 is possible.

Finally, the present invention is explained with respect to a spray plan with material change, a spray plan with change of the casting speed and with respect to a temperature control during material change.

Spray plan with material change:

In order to produce high-quality steels, each material group must be cooled using a separate spray plan. Without a tracking model, only one spray plan can be switched in the entire continuous casting plant. If the spray plan for the new material is switched over immediately when changing materials, the old material will receive the wrong amount of water. This can lead to poorer quality of the slab leaving the plant over the entire length of the cooling area.

When using the tracking according to the invention, it is known in which cooling zone the material change is located (see the point marked with the arrow in 5 , at a distance of about 6.5 meters from the mold level). Cooling zones in which only the old material is present receive the water quantities from the old spray plan, whereas the other cooling zones are supplied with water quantities according to the new spray plan.

If a cooling zone 102 consists of several (at least two) subcooling zones 106, the water quantity can be switched separately in each of these subcooling zones 106, depending on the position of the material change. The total water quantity of a cooling zone can be distributed linearly across the subcooling zones. As a rule, the specific water loading in a continuous casting plant decreases from the top of the plant (mold) to the end of the plant. This factorization can now also be transferred to the subcooling zones 106 according to the invention.

The following example illustrates this:

A material requires 100 l/min in the cooling zone "i". With two subcooling zones 106 of equal length and a linear distribution, 50 l/min of water is applied to each subcooling zone. In order to reduce the water application within the cooling zone "i" towards the end of the system, 60 l/min can be switched to the first subzone and 40 l/min to the second subzone.

Spray plan when changing the pouring speed:

In contrast to a change in material or width, a change in casting speed has an immediate effect on the entire strand. Direct tracking of the casting speed therefore makes no sense. Higher water quantities are stored in the injection plan for higher casting speeds.

Without tracking, the entire strand would immediately be exposed to the new amount of water if the casting speed were to change. With the so-called lifetime control, the water quantities are changed over the “lifetime” of the strand using the invention and the calculation model 122 with which the process computer 121 is equipped. A new section of the cast strand 20 that is leaving the mold immediately receives the new water quantities, whereas the section of the cast strand 20 that is leaving the last cooling zone 102 of the supporting strand guide 100 still receives the old amount of water. For all other zones, the water exposure is interpolated over the strand age. For this purpose, the strand age (or the age of the cast strand 20) is calculated for each calculation point in the casting direction G using the calculation model 122 and passed on to the next system position with the casting speed. A division into subcooling zones 106 refines the water exposure as a function of the strand age when the casting speed changes.

Temperature control when changing materials:

For all material groups, there are separate target temperature curves, similar to the injection plans. This means that a change in material is usually also associated with a change in the target temperature curve. Without tracking the position of the material change, the entire old casting strand 20 still in the system would be exposed to the water quantities according to the new temperature curve.

With the tracking according to the invention, the cooling zones in which only the new material is located can be supplied with the water quantities of the new temperature curve. The old outgoing strand receives the old water quantities. In the cooling zone in which the material change is currently taking place, the target temperature can be linearly interpolated from the old and the new target value from the current position of the material change. Since the strand head is often downgraded with a new ladle, it can be advantageous to produce the outgoing strand in the highest quality. To do this, cooling is always carried out with the old temperature curve in a cooling zone in which the material change is currently taking place. The old strand then has the optimal quality until the end - in contrast, the poor quality of the strand head is only further deteriorated with the new material. A division into subcooling zones 106 reduces the length of the incorrectly cooled strand section, meaning that less steel has to be downgraded.

List of reference symbols

10

Continuous casting plant

12

Cooling segments

15

Mould

16

Pouring level

18

Secondary cooling (of the continuous casting plant 10)

20

Casting strand

23

Signal path

24

Database or data storage

26

(Temperature) sensor

28

Data collection

F/G

Conveying direction or casting direction (for casting strand 20)

PD

Process data

100

supporting strand guide

101

Support roller(s)

102

Cooling zone(s)

104

Fluid outlet

105

Row (of fluid outlets 104)

106

Subcooling zone(s)

106.1

first subcooling zone

106.2

second subcooling zone

107.1

Control circuit (for the supply of cooling medium)

107.2

Control circuit (for the supply of cooling medium)

108.1

Control circuit (for the supply of cooling medium)

108.2

Control circuit (for the supply of cooling medium)

109.1

Control circuit (for the supply of cooling medium)

109.2

Control circuit (for the supply of cooling medium)

110

Control circuit (for the supply of cooling medium)

121

Process computer

122

Calculation model

130

Temperature profile of the core of the cast strand 20

132

Temperature profile of the average shell temperature of the cast strand 20

134

Temperature profile of the center of the top of the cast strand 20

B

Width (of the cast strand 20)

M

Central area (of a row 105 of fluid outlets 104)

R

Edge area (of a row 105 of fluid outlets 104)

W

Effective range (of a fluid outlet 104)

Z1

first zone (within an edge region R of a row 105 of fluid outlets 104)

Z2

second zone (within an edge region R of a row 105 of fluid outlets 104)

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 102018220386 A1 [0002]

Claims (19)

Supporting strand guide (100) for a continuous casting plant (10), each comprising a plurality of cooling zones (102), wherein in a cooling zone (102) at least one row (105) of fluid outlets (104) extending transversely to the casting direction (G) of the continuous casting plant (10) is provided for discharging at least one cooling medium, preferably water or a two-component mixture consisting of cooling water and compressed air, in the direction of a cast strand (20), characterized in that at least one cooling zone (102) of the supporting strand guide (100), preferably a plurality of the cooling zones (102) or all cooling zones (102), each has at least two subcooling zones (106) with associated rows (105) of fluid outlets (104) each extending transversely to the casting direction (G) of the continuous casting plant (10), wherein the subcooling zones (106) - seen in the casting direction (G) of the continuous casting plant (10) - are arranged one after the other and have a different cooling capacity compared to one another, in that a different amount of cooling medium can be discharged in the direction of the cast strand (20) from the fluid outlets (104) which are assigned to the respective subcooling zones (106). Strand guide (100) to Claim 1 , characterized in that the subcooling zones (106) within a cooling zone (102) - seen in the casting direction (G) of the continuous casting plant (10) - have a continuously decreasing cooling capacity compared to one another. Strand guide (100) to Claim 1 or 2 , characterized in that a plurality of rows (105) of fluid outlets (104) are arranged within a subcooling zone (106) and are thus combined to form this subcooling zone (106), wherein these rows (105) of fluid outlets (104) each extend transversely to the casting direction (G) of the continuous casting plant (10) and - viewed in the casting direction (G) of the continuous casting plant (10) - are each arranged one after the other and parallel to one another. Strand guide (100) to Claim 1 or 2 , characterized in that a subcooling zone (106) is formed by a single row (105) of fluid outlets (104), said row (105) of fluid outlets (104) extending transversely to the casting direction (G) of the continuous casting plant (10). Strand guide (100) according to one of the preceding claims, characterized in that at least one cooling zone (102) of the supporting strand guide (100) has subcooling zones (106) at least in the form of a first subcooling zone (106.1) and a second subcooling zone (106.2), wherein the first subcooling zone (106.1) - seen in the casting direction (G) of the continuous casting plant (10) - is arranged in front of or upstream of the second subcooling zone (106.2) and has a greater cooling capacity compared to the second subcooling zone (106.2). Strand guide (100) according to one of the preceding claims, characterized in that the fluid outlets (104) of the individual subcooling zones (106) are each equipped with nozzles. Strand guide (100) to Claim 6 , as far as related to Claim 5 , characterized in that the nozzles in the first subcooling zone (106.1) have a larger output size compared to the nozzles in the second subcooling zone (106.2), so that a larger amount of cooling medium can be discharged from the nozzles in the first subcooling zone (106.1) compared to the second subcooling zone (106.2). Strand guide (100) according to one of the Claims 5 until 7 , characterized in that the fluid outlets (104) in the individual subcooling zones (106.1, 106.2) are each connected to different control circuits (110) of cooling medium, so that a larger amount of cooling medium can be discharged from the fluid outlets (104) of the first subcooling zone (106.1) in comparison to the second subcooling zone (106.2). Strand guide (100) to Claim 8 , characterized by a process computer (121) which is programmed with a calculation model (122) and is connected to the individual control circuits (110) for the subcooling zones (106) in terms of signals, wherein changing process data of a continuous casting process can be recorded by the process computer (121) and the individual control circuits (110) for the subcooling zones (106) can be controlled on the basis of these changed process data by means of the calculation model in order to thereby achieve a predetermined application of a cooling medium to the cast strand (20) in the individual subcooling zones (106). Strand guide (100) according to one of the preceding claims, characterized in that at least one row (105) of a subcooling zone (106; 106.1, 106.2) of fluid outlets (104) extending transversely to the casting direction (G) of the continuous casting plant (10) has a central region (M) and adjacent edge regions (R), wherein on the one hand the central region (M) and on the other hand the two edge regions (R) are each connected to different control circuits (107.1; 108.1; 107.2, 108.2) are connected for the supply of cooling medium, such that the cooling capacity in the two edge regions (R) is variable in comparison to the cooling capacity in the central region (M). Continuous casting plant (10) for producing a metallic product, comprising a mold (15) and a supporting strand guide which - viewed in the casting direction (G) of the continuous casting plant (10) - is arranged downstream of the mold (15), characterized in that the supporting strand guide is in the form of a strand guide (100) according to one of the Claims 1 until 10 is trained. Method for cooling a cast strand (20) moved in a supporting strand guide (100) of a continuous casting plant (10), in which the supporting strand guide (100) has a plurality of cooling zones (102) which - viewed in the casting direction (G) of the continuous casting plant (10) - are arranged one after the other, wherein in each cooling zone (102) at least one row (105) of fluid outlets (104) extending transversely to the casting direction (G) of the continuous casting plant (10) is provided for discharging at least one cooling medium, preferably water or a two-component mixture consisting of cooling water and compressed air, in the direction of the cast strand (20), characterized in that the cast strand (20) passes through at least two subcooling zones (106) provided in at least one cooling zone (102) of the supporting strand guide (100), wherein these subcooling zones (106) - viewed in the casting direction (G) of the continuous casting plant (10) - are arranged one after the other and have a different cooling capacity compared to one another, in that a different amount of cooling medium is discharged in the direction of the cast strand (20) from fluid outlets (104) which are assigned to the respective subcooling zones (106). Procedure according to Claim 12 , characterized in that the subcooling zones (106) within a cooling zone (102) - seen in the casting direction (G) of the continuous casting plant (10) - have a continuously decreasing cooling capacity compared to one another. Procedure according to Claim 12 or 13 , characterized in that a cooling zone (102) of the supporting strand guide (100) has subcooling zones (106) at least in the form of a first subcooling zone (106) and a second subcooling zone (106), wherein the first subcooling zone (106) - seen in the casting direction (G) of the continuous casting plant (10) - is arranged in front of or upstream of the second subcooling zone (106) and has a greater cooling capacity compared to the second subcooling zone (106). Procedure according to Claim 14 , characterized in that the fluid outlets (104) of the individual subcooling zones (106) are each equipped with nozzles, wherein the nozzles in the first subcooling zone (106.1) have a larger output size compared to the nozzles in the second subcooling zone (106.2), so that a larger amount of cooling medium is discharged from the nozzles in the first subcooling zone (106.1) for cooling the cast strand (20) compared to the second subcooling zone (106.2). Procedure according to Claim 14 or 15 , characterized in that the fluid outlets (104) in the first subcooling zone (106.1) and the fluid outlets (104) in the second subcooling zone (106.2) are each connected to different control circuits (110) for the supply of cooling medium, so that a smaller amount of cooling medium is discharged from the fluid outlets (104) of the second subcooling zone (106.2) for cooling the cast strand (20) in comparison to the first subcooling zone (106.1). Method according to one of the Claims 12 until 16 , characterized in that at least one row (105) of fluid outlets (104) of a subcooling zone (106; 106.1, 106.2) extending transversely to the casting direction (G) of the continuous casting plant (10) has a central region (M) and adjacent edge regions (R), wherein on the one hand the central region (M) and on the other hand the two edge regions (R) are each connected to different control circuits (107.1; 108.1; 107.2, 108.2) for the supply of cooling medium, such that the cooling capacity in the two edge regions (R) is changed in comparison to the cooling capacity in the central region (M). Procedure according to Claim 16 or 17 , characterized in that a process computer (121) is provided which is programmed with a calculation model (122) and is connected in terms of signals to the individual control circuits (110) for the subcooling zones (106), wherein changing process data of a continuous casting process are recorded by the process computer (121) and the individual control circuits (110) for the subcooling zones (106) are controlled on the basis of these changed process data by means of the calculation model in order to thereby achieve an application of a predetermined amount of cooling medium to the cast product in the individual subcooling zones (106). Procedure according to Claim 18 , characterized in that the changing process data of the continuous casting process are selected from the group consisting of material change, casting temperature, casting speed and a derived age of the cast strand (20) in a specific cooling zone (102) and an associated subcooling zone (106; 106.1, 106.2), strand geometry and/or mold cooling.

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