EP2361699A1 - Method for cooling sheet metal with a cooling section, cooling section and control and/or regulating device for a cooling section - Google Patents

Abstract

The method for cooling a sheet metal (B) using a cooling section (1), which includes first coolant delivery devices (2) for cooling a sheet metal upper side (O) and second coolant delivery devices for cooling a sheet metal lower side (U), comprises achieving a predetermined target state of the sheet metal at a reference point by cooling during and/or after discharging from the cooling section, and determining a coolant delivery for first and second coolant delivery devices, where the first and second coolant delivery devices are oppositely arranged relative to the sheet metal. The method for cooling a sheet metal (B) using a cooling section (1), which includes first coolant delivery devices (2) for cooling a sheet metal upper side (O) and second coolant delivery devices for cooling a sheet metal lower side (U), comprises achieving a predetermined target state of the sheet metal at a reference point by cooling during and/or after discharging from the cooling section, and determining a coolant delivery for first and second coolant delivery devices, where the first and second coolant delivery devices are oppositely arranged relative to the sheet metal. The determination of the coolant delivery of the coolant delivery devices takes place based on a predetermined heat stream to be supplied from the sheet metal side turned towards the respective coolant delivery device, where a surface temperature of the sheet metal is considered for the heat stream to be supplied. A ratio of the heat steam to be supplied from the sheet metal upper side to the sheet metal lower side is adjusted in dependent of a flatness of the sheet metal when it enters into the cooling section, where the ratio is equal to one when the even sheet metal running into the cooling section. The ratio is adjusted when the uneven sheet metal running into the cooling section, so that the flatness of the sheet metal after passing through the cooling section is reduced relative to the unflatness of the sheet metal before passing through the cooling section. The determination step takes place based a specified equation. The coolant delivery for the coolant delivery devices is determined independent of the coolant delivery of the other opposite coolant delivery device relative to the sheet metal. The determination step takes place, so that the sheet metal is virtually divided into a first sheet metal and a second sheet metal parallel to the upper side or lower side, where the coolant delivery is separately determined for the first and second sheet metals. During the respective determination, a heat exchange is considered between the first and second sheet metals. For the first and second sheet metals, an individual temporal progression of a parameter described to an energetic state of the sheet metal is determined. The heat stream to be supplied for the sheet metal upper side and the sheet metal lower side is determined based on the parameter. During the consideration of the determination of the coolant delivery, the temperature of the sheet metal upper side and/or the temperature of the sheet metal lower side is always greater or equal to a predetermined boundary temperature of 350[deg] C during the passage through the cooling section. One of the sheet metal sides has a temperature that is greater or equal to the predetermined boundary temperature and is turned towards the coolant delivery device. Independent claims are included for: (1) a control- and/or regulating device for a cooling section; (2) a machine-readable program code for a control- and/or regulating device for a cooling section; (3) a storage medium with a machine-readable program code; and (4) a cooling section for cooling a sheet metal.

Description

The invention relates to a method for cooling a sheet, in particular heavy plate, by means of a cooling section, wherein the cooling section comprises a plurality of coolant delivery means for cooling a top sheet and a plurality of coolant delivery means for cooling a bottom sheet, wherein by means of cooling a predetermined target state of the sheet on a Reference point is achieved at and / or after exiting the cooling section, wherein a coolant delivery for a first and a second coolant delivery device is determined, wherein the first and the second coolant discharge means are arranged relative to the sheet opposite. Furthermore, the invention relates to a method for cooling a sheet by means of a cooling section, wherein the cooling section comprises a plurality of coolant discharge means for cooling a sheet metal top and a plurality of coolant delivery means for cooling a sheet metal bottom, wherein by means of cooling a predetermined target state of the sheet at least and / or is reached after exiting the cooling section, wherein a coolant delivery is determined for at least one of the coolant discharge device. Moreover, the invention relates to a control and / or regulating device for a cooling section.

The invention is in the technical field of rolling mills, in particular plate rolling mills and in particular relates to the cooling of heavy plate.

The cooling or operation of the cooling section significantly influences the quality and properties of the sheet produced. The cooling section of a plate mill is used in particular to adjust the material properties of the sheet in the desired manner.

When cooling heavy plate, it can lead to unevenness due to the relatively high thickness and the associated heat content during cooling, which are caused by thermal stresses. These thermal stresses can be influenced by the operation of the cooling section. The aim is always to produce a flat sheet, which has the desired mechanical properties.

Heavy plate usually has a thickness of 3 mm or more and thus complies with the definition according to EN 10029.

From the European patent application EP 2070608 A1 For example, a method for cooling plate is known. Here, a coolant delivery of the actuators above and below the sheet is set individually, in particular such that the same heat transfer coefficient is present for the sheet metal top and the sheet metal bottom. This has the disadvantage that, despite the comparatively exact determination of the heat transfer coefficient, unevenness in the cooling section can continue to arise. Also, this could not be remedied any unevenness of the sheet, which have arisen before the cooling section.

The object of the invention is to further increase the flatness of manufactured heavy plate in the production of heavy plate while high throughput of the plate mill.

The procedural part is achieved by a method for cooling a sheet by means of a cooling section, wherein the cooling section comprises a plurality of coolant discharge means for cooling a sheet top and a plurality of coolant discharge means for cooling a sheet bottom, wherein by means of cooling a predetermined target state of the sheet at a reference point , in particular at the latest, at and / or after leaving the cooling section, wherein a coolant delivery is determined for a first and a second coolant delivery device, wherein the the first and the second coolant delivery device are arranged opposite to the sheet opposite, wherein the determination of the coolant delivery for the first and second coolant delivery device based on a predetermined dissipated heat flow from the respective coolant delivery device facing sheet metal side, wherein for each dissipated heat flow, a temperature, in particular surface temperature, the respective sheet side is taken into account.

The inventor has recognized that it is not sufficient for the best possible compliance with the flatness, only to take into account the heat transfer coefficients for each top and bottom and to match these.

Rather, as flat as possible sheet metal, for example. Will be achieved if - at plan incoming sheet - the heat flow for the top and bottom is the same size. For this, however, the temperature of the top and the bottom must be explicitly taken into account, since this directly influences the dissipated heat flow. This is not considered in the prior art. Rather, in the prior art, the equality of the heat transfer coefficient for top and bottom sought. At different temperatures of the upper side of the sheet metal and the lower side of the sheet, however, this leads precisely to an uneven heat flow for the upper and lower side, which can cause an unevenness in the case of a sheet entering the sheet. This can be avoided by the present invention.

The temperature of the upper side of the sheet or underside of the sheet can be determined by means of a measurement, for example by means of a pyrometer. Alternatively, it is also possible to use calculated actual temperatures, for example known from a sheet-metal tracking calculation.

Under coolant delivery is understood both the quantitative release of the coolant per unit time, as well as the manner of delivery of the coolant, for example. The setting of the application angle, etc .... Often, only the amount of coolant per unit time is set.

As a coolant dispensing means, a device is considered which is designed for dispensing coolant on the sheet.

The coolant delivery device may be a single switchable valve assembly having one or more coolant outlets. Alternatively, this may also be a plurality of individually switchable valve-outlet devices, which are jointly controlled or operated. The first embodiment is preferred for the invention, since this allows a more flexible adjustment or a more flexible operation of the cooling section.

Preferably, all the coolant delivery devices of the cooling section, both for cooling the sheet metal underside, as well as for cooling the sheet metal top, are each formed as individually switchable valve arrangements with associated coolant outlets.

As a final state for a sheet, a desired temperature to be reached or a desired microstructure or a desired phase composition of the sheet can be considered. The final state ensures that a desired product is actually provided by the cooling path of the plate rolling mill. If the final state is not reached, the product produced is generally inferior or discard as scrap.

In an advantageous embodiment of the invention, a ratio of dissipating heat flow from the top side of the sheet to the underside of the sheet is set as a function of a flatness of the sheet, in particular when it enters the cooling section. This makes it possible to act on the sheet by means of the cooling path or the cooling, as it is needed. In particular, by means of the cooling section corrective to be acted upon the flatness of the sheet, if necessary. As a result, the cooling section can be used to maintain product quality, since on the one hand already unplanes sheet can be converted into flat sheet, on the other hand plan flat in the cooling section incoming sheet also runs out plan from the cooling section. Advantageously, for this purpose, the control and / or regulating device for the cooling section can be operatively connected to a flatness measuring device in front of the cooling section, so that the cooling section can be controlled and / or regulated in accordance with the detected flatness, in particular such that the unevenness of one in the Cooling line incoming unplaned sheet metal are reduced and flat in the cooling section incoming sheet is maintained.

In a preferred embodiment, the ratio of the heat flow to be dissipated from the top side and the heat flow to be dissipated from the bottom side is essentially equal to one for a flat sheet, in particular a sheet entering the cooling section. That the dissipated heat per unit time on the top is equal to the heat dissipated per unit time on the bottom. Due to the possibly different temperatures and the different coolant residence time on the sheet, in particular for sheet metal top and bottom sheet, this means that for the top and bottom different amounts of coolant must be applied.

In a further advantageous variant of the invention, the ratio is set such that the unevenness of the sheet is reduced after passing through the cooling section relative to the unevenness of the sheet before passing through the cooling section with an unplaned sheet metal. Not only does this ensure that a desired product is produced by means of the cooling section, but also the quality of the product produced can be influenced with regard to flatness by means of the cooling section. It can in particular by a correspondingly adapted cooling, ie corresponding unequal distribution of the heat flow for top sheet metal and bottom sheet, flatness error of the sheet in the cooling section can still be corrected, which possibly increases the yield of the plate mill.

wobei
x: ein vorgebbarer Faktor zwischen 0 und 1 ist, wobei dieser von der Planheit des in die Kühlstrecke einlaufenden Blechs oder einer Temperatur, insbesondere einer Temperaturdifferenz zwischen Blechoberseite und Blechunterseite, abhängen kann,
j _oben: ein abzuführender Wärmestrom von der Oberseite des Blechs,
j _unten: ein abzuführender Wärmestrom von der Unterseite des Blechs, und
j _ges: ein abzuführender und vorzugebender Gesamtwärmestrom.It is particularly advantageous to determine the coolant delivery for the first and second coolant delivery devices by means of the following equations: $$\begin{array}{c}0=x\cdot j_{\mathit{above}}-\left(1-x\right)\cdot j_{\mathit{below}}\\ \hfill j_{\mathit{ges}}=j_{\mathit{above}}+j_{\mathit{below}}\end{array}$$

in which
x: a predeterminable factor between 0 and 1, which may depend on the flatness of the sheet entering the cooling section or a temperature, in particular a temperature difference between the upper side of the sheet metal and the underside of the sheet,
j _above : a dissipated heat flow from the top of the sheet,
j _down : a dissipated heat flow from the bottom of the sheet, and
j _ges : a total heat flow to be dissipated and specified.

The respective heat flow can be modeled via an empirical, physical or empirical-physical model. This can be determined by the expert, for example, with the help of cooled in the past sheets. The model of the heat flow is usually at least a function of the respective temperature of the sheet side, the respective temperature of the coolant, which is used for cooling, the sheet speed, and the amount of coolant. Other parameters may occur, such as the rate at which the coolant impinges on the sheet surface.

Based on the above equation system, a coolant quantity for a coolant delivery device can then be determined in order to set a desired heat flow. Preferably, additionally or as a secondary condition, that during the passage of the cooling section the temperature of the top side of the sheet and / or the temperature of the underside of the sheet is always greater than or equal to a predetermined limit temperature, in particular 350 ° C. As the limit temperature, a surface temperature of the sheet is preferably used. The amount of the limit temperature is, for example, determined such that the cooling effect principle for the entire cooling section is the same. If the cooling effect principle for the sheet changes as it passes through the cooling section, the cooling becomes difficult to control. For this reason, it is provided to operate the cooling section in such a way that this limit temperature is preferably not exceeded by either the upper side of the sheet or the underside of the sheet during the passage of the cooling section. For this one can either reduce j _ges so far that the mentioned secondary condition is taken into account (= additional), or one can subsequently reduce the calculated heat flow on the side, which would otherwise lead to an undershooting (= substitute), that the undershooting does not he follows.

For example. the limit temperature can be selected from a temperature range of 420 ° C to 300 ° C. In this surface temperature range of the sheet occurs - depending on the respective cooling conditions in a cooling section - in particular on the top of a change in the coolant behavior in the cooling of the sheet, which is accompanied by a change of the cooling mechanism or cooling effect principle. This change leads to difficult-to-control cooling conditions, which lead to the sheet unscheduled leaking out of the cooling section. By setting a limit temperature, which must not be less than the sheet top and / or the sheet underside, and taking into account this limit temperature in determining the coolant delivery, it can be ensured that a critical, hardly controllable for the cooling temperature regime of the sheet surface during the passage of the sheet through the cooling section is avoided. While the operation of the coolant dispensers located above and below the sheet is coupled in the above manner by using a system of equations, alternatively, a separate calculation may be made for coolant dispensers located above and below the sheet.

In an alternative advantageous embodiment, the coolant delivery is determined for at least one of the coolant delivery devices, regardless of the coolant delivery of another coolant delivery device, in particular a relative to the sheet opposite coolant delivery device.

This is possible because at two-sided heat dissipation in the thickness direction of the sheet there is at least one point at which the heat flow disappears or is equal to zero. There is no heat exchange for this point in the thickness direction. The sheet can be thought-divided at this point, without changing the result. Therefore, a calculation of the dissipated heat flow or a quantity of coolant required for this purpose can generally be carried out on one side adiabatically, i. it must be considered in the calculation of one side, for example, the top, not the interaction with the other side, for example, the bottom of the sheet.

Advantageously, the determination is carried out such that the sheet, in particular without explicit calculation of the above point, substantially parallel to the top or bottom is virtually divided into a first sheet and a second sheet, the coolant delivery each separately for the first and the second Sheet is determined, with the respective determination, a heat exchange between the first sheet and the second sheet is disregarded.

In other words, this means that for the first sheet, for example, the upper, the amount of coolant is determined, wherein for the second sheet, eg the lower sheet, facing interface of the first sheet no heat exchange is taken into account. Furthermore, the coolant delivery for the second, eg the lower, sheet is calculated, with no heat exchange being taken into account for the boundary surface of the second sheet facing the first sheet. The heat exchange between the first and the second sheet thus remains uncorrected computationally. This gives an equation with an unknown, which is thus solvable.

The term "virtual" in this context means that the division of the sheet takes place only from a calculation perspective. There is therefore no actual, i. physical, division of the sheet.

For the above separate calculation for first sheet metal and second sheet is advantageously proceeded such that in each case an individual, in particular temporal course of an energetic state of the sheet descriptive size is determined for the first sheet and the second sheet, based on which a dissipated heat flow for the respective top side of the sheet metal and the underside of the sheet is determined. For example, a variable, in particular calculated, actual temperature profile, actual enthalpy profile or a course of another suitable variable can be used as the variable describing the energetic state. When using a time course of this is preferably given individually for a variety of defined sheet metal sections, so that the greatest possible dynamics is achieved for the cooling and the entire sheet has consistently the desired properties.

Preferably, it is taken into account for the determination of the coolant delivery that, during the passage through the cooling section, the temperature of the top side of the sheet and / or the temperature of the underside of the sheet are always greater than or equal to a predetermined limit temperature, in particular 350 ° C. As the limit temperature, a surface temperature of the sheet is preferably used. The amount of the limit temperature is, for example, such determines that the cooling effect principle is the same for the entire cooling section. If the cooling effect principle for the sheet changes as it passes through the cooling section, the cooling becomes difficult to control. For this reason, it is provided to operate the cooling section in such a way that this limit temperature is preferably not exceeded by either the upper side of the sheet or the underside of the sheet during the passage of the cooling section. In this method, simply the predetermined boundary surface temperature is taken into account as a secondary condition in the determination of the respective heat flow.

The object is likewise achieved by a method for cooling a sheet by means of a cooling section, the cooling section having a plurality of coolant delivery devices for cooling a sheet metal top side and a plurality of coolant delivery devices for cooling a sheet metal bottom, wherein by means of cooling a predetermined target state of the sheet at least at and is reached after exiting the cooling section, wherein a coolant delivery is determined for at least one of the coolant delivery devices, is taken into account in the determination of the coolant delivery for at least one of the coolant delivery devices that the sheet side, which faces this coolant delivery device, in particular during the implementation of Cooling, always has a temperature greater than or equal to a predetermined limit temperature.

Regardless of the manner of cooling a sheet in a cooling section, it is desirable to avoid getting into a temperature range of the sheet at which the cooling mechanism of the cooling section changes. The cooling mechanism is usually determined by the behavior of the coolant on the sheet, for example formation of steam cushions in water cooling, the manner of distribution of the vapor on the sheet, etc. If it comes due to the temperature profile of the surface of the sheet to a change in the behavior of the Coolant of the sheet and thus to a change in the cooling mechanism, This leads to a poor controllability of the cooling and thus to a product that does not usually correspond to the customer's wishes. For example. This is particularly the case on the top, when away from the immediate impact or directly in the vicinity of the coolant jet about excess, on the top effluent coolant is no longer separated by a vapor layer of the sheet surface, but uncontrolled in the liquid phase over the sheet moved while gradually evaporating.

In particular, there may be an unscheduled product when changing the cooling mechanism, since the heat flow due to the change of the cooling mechanism, especially on the top sheet is difficult to predict and difficult to predict. This leads to corresponding temperature deviations, which cause material stresses. These cause the sheet to distort and become unplaned.

By considering a limit temperature in the determination of the coolant delivery, this problem can be avoided, whereby the flatness of the sheet is improved at the same time high throughput.

The object is also achieved by a control and / or regulating device for a cooling section, with a machine-readable program code, which comprises control commands which cause the control and / or regulating device in its execution for carrying out the method according to one of claims 1 to 10.

The invention further extends to a machine-readable program code for a control and / or regulating device for a cooling section, wherein the program code has control commands which cause the regulating and / or control device to carry out the method according to one of claims 1 to 10.

In addition, the invention extends to a storage medium with a stored thereon machine-readable program code according to claim 12. As a storage medium, all storage media in question, on which the corresponding program code can be stored, for example. This CDs, DVDs, flash memory storage, such as USB Sticks, or memory cards.

The object is likewise achieved by a cooling section for cooling sheet metal, the cooling section having a plurality of coolant delivery devices for cooling a sheet metal top side and a plurality of coolant delivery device for cooling a sheet metal underside, wherein the cooling section is operatively connected to a control and / or regulating device according to claim 11 is, wherein the coolant discharge means by means of the control and / or regulating device according to claim 11 are controllable and / or controllable. As a result, a cooling section is provided, by means of which the flatness of the sheet to be cooled is improved.

FIG 1

eine schematische Darstellung einer Kühlstrecke zum Kühlen von Grobblech mit einer Mehrzahl an Kühlmittelabgabeeinrichtungen,

FIG 2

ein Ablaufdiagramm zur Ermittlung einer Kühlmittelabgabe für eine Kühlmittelabgabeeinrichtung auf Basis eines Gleichungssystems,

FIG 3

ein Ablaufdiagramm zur Ermittlung einer Kühlmittelabgabe für eine Kühlmittelabgabeeinrichtung auf Basis einer getrennten Ermittlung für Blechoberseite und Blechunterseite

FIG 4

ein Ablaufdiagramm zur Ermittlung einer Kühlmittelabgabe unter Berücksichtigung einer Grenztemperatur.

Further advantages of the invention will become apparent from an embodiment which is explained in more detail below with reference to the schematic drawings. Show it:

FIG. 1

a schematic representation of a cooling section for cooling heavy plate with a plurality of coolant delivery devices,

FIG. 2

a flowchart for determining a coolant delivery for a coolant delivery device based on a system of equations,

FIG. 3

a flowchart for determining a coolant delivery for a coolant delivery device based on a separate determination for sheet top and bottom sheet

FIG. 4

a flowchart for determining a coolant delivery taking into account a limit temperature.

FIG. 1 shows an exemplary cooling section 1 for cooling heavy plate B. This is part of a heavy plate mill, not shown in detail.

The cooling line 1 comprises a plurality of coolant delivery devices 2, which are arranged both above and below the sheet B. Their coolant delivery is individually adjustable, whereby the greatest possible flexibility and dynamics of the cooling section 1 is possible.

Frequently, each coolant delivery device 2 of the cooling section 1 is associated with a directly opposite coolant delivery device 2. If these coolant delivery devices arranged directly opposite one another are in operation, they each cool the same sheet metal section. The coolant delivery device 2 arranged above the metal sheet cools an upper side O of the sheet metal section, while the coolant discharge device 2 arranged below the sheet B cools a lower side U of the sheet metal section.

Furthermore, the cooling section 1 is preceded by a flatness measuring device 3 in the direction of mass flow, by means of which a flatness of the sheet B entering the cooling section 1 can be detected.

In the present embodiment, the cooling section 1 are further preceded by two temperature measuring devices 4 and 5, of which the above the sheet B arranged temperature measuring device 4 detects the temperature of the top sheet metal O and arranged below the sheet B temperature measuring device 5, the temperature of the sheet bottom U. Alternatively, the temperature be determined by sheet metal top O and / or bottom plate U before entering the cooling section 1 by means of a model. As a rule, the sheet B is calculated divided into a plurality of sheet metal sections and each of these sheet metal sections is followed by calculation, the actual temperature of the top sheet metal and / or the bottom sheet for a particular sheet metal section be determined at a predetermined reference point in front of the cooling section by means of sheet metal tracking calculation. This has the advantage that the temperature measuring devices 4, 5 can be omitted in whole or in part before the cooling section 1. In the event that only one temperature measurement, z. B. a temperature measurement on the top, is present, the temperature distribution calculated by a model on the sheet thickness based on the temperature measurement initially adapted so that measured and calculated temperature on the side of the measurement match. Then the calculated value on the opposite side, where the measurement is missing, can be taken from the model.

Furthermore, the cooling section has a temperature measuring device 6, which is arranged behind the cooling section 1 in the direction of mass flow. These temperature values detected after the cooling line 1 can be used to correct, e.g. in the context of a model adaptation, the calculation of the coolant delivery are used.

The coolant delivery device 2, the temperature detection devices 4, 5 and 6, and the flatness measuring device 3 is or are operatively connected to a control and / or regulating device 10. By means of the control and / or regulating device 10, the operation of the cooling section 1, in particular the coolant delivery, controlled or regulated. On this control and / or regulating device 10, therefore, the corresponding calculation method for determining the coolant delivery are deposited.

In particular, the control and / or regulating device 10 has a machine-readable program code 12. This includes control commands which cause the control and / or regulating device 10 to carry out an embodiment of the method according to the invention. The machine-readable program code 12 is stored, for example, by means of a storage medium 11, for example a CD, a DVD, a flash memory device, for example a USB stick, or other data carriers. Alternatively, you can the machine-readable program code 12 is supplied to the control and / or regulating device 10 via a network.

In particular, the machine-readable program code 12 is stored on a storage medium, which is part of the control and / or regulating device 10.

The following describes methods which can be advantageously carried out with a cooling section 1 configured in this way.

FIG. 2 shows a flowchart according to which the coolant delivery, in particular the amount of coolant to be dispensed per unit time, for a pair of directly opposite arranged coolant discharge means is determined.

In a method step 100, the temperature To of the upper side of the sheet metal and the temperature Tu of the underside of the sheet are determined. This can be done, for example, by means of a measurement, as in accordance with FIG. 1 Alternatively, these temperatures can be determined from the running model calculations.

In a process step 101, based on the desired target state of the sheet after the cooling section, a total heat flow is determined, which is required, the sheet from its known initial state in front of the two opposite coolant discharge devices in the desired final state behind the two opposite coolant delivery devices, e.g. to a desired initial state before the two next opposite coolant discharge devices or the cooling stop temperature. Characterized in that the temperature of the top surface of the sheet metal and the underside of the sheet is known, this can be done with increased accuracy.

Thus, for each pair of oppositely disposed coolant delivery devices, a total heat flow resulting from This pair should be removed so that the desired final state of the sheet is achieved.

This required total heat flow is now to be distributed among the individual coolant delivery device pairs, taking into account that a predetermined limit temperature of the top side of the sheet metal and the underside of the sheet metal must not be exceeded. It is also taken into account that the dissipated heat flow is strongly temperature-dependent. Furthermore, the flatness of the sheet before entry into the cooling section is taken into account.

For this purpose, a numerical value x, 0 < x <1 is first determined in a method step 102, for example, depending on the flatness measured value of the sheet. This can be done, for example, by means of a table which, for a given flatness measured value, has a suitable value for x z. X = 0.5 for sheet metal, x = 0.6 for sheet bent slightly upwards and x = 0.4 for sheet bent slightly downwards.

die Wärmeströme der Oberseite, j_oben und der Unterseite, j_unten , berechnet. Dabei bezeichnet x die im Schritt 102 berechnete Konstante. Sodann wird mittels des Modells geprüft, ob eine vorgegebene Grenztemperatur der Blechoberseite und der Blechunterseite unterschritten wird. Ist dies nicht der Fall, kann sofort mit dem Schritt 103 mit a=1 weiterverfahren werden. Ist dies der Fall, wird eine Zahl a, 0 < a <1, derart berechnet, dass bei Anwendung der Wärmeströme aj_oben anstelle J_oben und/oder aj_unten anstelle j_unten bei größtmöglichem Wert von a diese Grenztemperatur gerade noch eingehalten wird. Mit diesen Wärmeströmen wird dann mit Schritt 103 weiterverfahren.Then, in method step 103, the total heat flow j _ges determined in method step 101 is distributed to the two coolant delivery devices. From the total heat flow j _ges determined in method step 101, first, by means of the equation $$\begin{array}{c}0=x\cdot j_{\mathit{above}}-\left(1-x\right)\cdot j_{\mathit{below}}\\ \hfill j_{\mathit{ges}}=j_{\mathit{above}}+j_{\mathit{below}}.\end{array}$$

the heat flows of the top, j _top and bottom, j _down , calculated. In this case, x denotes the constant calculated in step 102. Then it is checked by means of the model, whether a predetermined limit temperature of the upper side of the sheet metal and the underside of the sheet is exceeded. If this is not the case, it is immediately possible to continue with step 103 with a = 1 . If this is the case, a number a, 0 <a <1, is calculated such that when applying the heat flows aj _above instead of J _above and / or aj _down instead of j _down at the maximum value of a, this limit temperature just barely maintained becomes. These heat flows then proceed to step 103.

From this, the coolant quantities for the coolant delivery device can be determined above the metal sheet and below the metal sheet for the respective pair of coolant devices. This takes place in a method step 104.

If, for example, a flat sheet enters the cooling section, the heat flow is set in such a way that the same heat flow is dissipated from the upper side of the sheet metal and the underside of the sheet, taking into account the different temperatures of the upper sheet side and the lower sheet side. Namely, since the temperature of the sheet upper side and the sheet lower side is generally different, this causes a change in the coolant amounts for the coolant discharge means arranged above the sheet and for the coolant discharge means located below the sheet compared to the coolant quantities determined according to the prior art. However, uniform cooling is only possible if the heat flow on the upper side of the sheet metal and the underside of the sheet is the same, which is achieved by a procedure according to one of the embodiments of the method according to the invention.

Possibly. can also be a targeted non-uniform cooling of the top sheet metal and bottom sheet be desired, eg., When the sheet enters already unplan in the cooling section. This is detected by means of the flatness measuring device. The result of the flatness measurement is thus included in the further operation of the cooling section, wherein the cooling is adjusted so that the unevenness of the sheet is counteracted.

Another reason for a non-uniform setting of the heat flow for the top side of the sheet metal and the underside of the sheet can also be an excessive difference in temperature between the sheet metal top and the underside of the sheet metal. This can be known today with methods of cooling lead to unevenness of the sheet in the cooling section. For example. If the temperature difference between the upper side of the sheet metal and the lower side of the sheet is too great, it may no longer be possible to cool the sheet such that the surface temperature always remains above a limit temperature, but at the same time a higher heat dissipation is required to obtain a flat sheet which also has the desired target state reached. The targeted unequal distribution of the heat flow between the upper side of the sheet and the underside of the sheet is suitable for reducing such temperature differences, and to produce a flat sheet.

This procedure is carried out for all opposite coolant delivery devices in this way. Whether this is to take place for further coolant dispensing devices arranged opposite one another is queried in each case in a method step 105.

If, for example, a final state of the sheet is achieved without further cooling, then no further query is required for a further coolant quantity determination for mass-flow downstream coolant delivery devices. Such a query step may advantageously be provided between method step 103 and method step 104. This avoids further calculation cycles whose result is already known from the outset, namely that the amount of coolant to be dispensed in these cases is equal to zero.

Thus, for the required pairs of coolant dispensing devices, a coolant quantity to be dispensed individually from the respective coolant dispensing device is determined, which ensures the achievement of the target state of the metal sheet while maintaining the corresponding boundary conditions.

Subsequently, a corresponding setting of the coolant delivery devices of the cooling section in the above manner, so that the desired final state of the sheet is achieved.

An alternative procedure for determining the coolant delivery is in FIG. 3 shown schematically.

According to FIG. 3 For the determination of the coolant delivery for the coolant delivery devices above and below the sheet, a calculation method is used which determines the coolant delivery or quantity separately for sheet metal top side and sheet metal bottom side. For this purpose, the sheet is computationally divided into an upper and a lower plate, with a heat exchange between this upper and lower plate is disregarded.

In a method step 200, a numerical value x , 0 < x <1 is first determined, for example, depending on the flatness measured value of the sheet. This can be done, for example, by means of a table which, for a given flatness measured value, has a suitable value for x z. B. x = 0.5 for flat sheet metal, x = 0.6 for sheet bent slightly upwards and x = 0.4 for sheet bent slightly downwards. Subsequently, the sheet is virtually divided at the height x into an upper sheet and a lower sheet. In this case, x means the ratio of the thickness of the lower sheet relative to the total sheet thickness. The division is made virtually at height x times sheet thickness, measured from the bottom of the sheet to the top.

In a method step 200, the temperature of the top side of the sheet metal and the bottom side of the sheet in front of the cooling section is determined. From this and in knowledge of the temperature profile in the thickness direction of the sheet, an average temperature for the upper sheet and an average temperature for the lower sheet is determined.

In a method step 201, for example, an average temperature profile over time for a specific sheet-metal section of the sheet is specified for the upper sheet, so that it is transferred from a known average initial temperature before cooling to an average desired final temperature. This happens analogously for the lower plate in one Process step 204. The predetermined temperature profiles are generally different for the upper sheet and the lower sheet due to the different initial temperature and the different coolant behavior on the sheet metal top and sheet metal underside. However, the final state to be achieved is usually the same for the upper and lower plates.

As an alternative to a temporal temperature curve, it is also possible to specify a local temperature profile for the two metal sheets. Also conceivable is a specification of a temporal or local enthalpy curve for the upper and lower sheet, so that the sheet reaches a desired final state.

In a method step 202 or 205, a respective heat flow for the upper or lower sheet is determined from the respective given course, which is required to set the desired curve for the upper sheet or the lower sheet. This is done with the usual physical equations describing the temperature evolution and the heat transfer.

In a method step 203 or 206, the coolant output, in particular the coolant quantity per unit time, for the coolant delivery device arranged above the metal sheet and for the coolant discharge device arranged below the metal sheet is determined from the determined heat flows for the upper metal sheet and the lower metal sheet.

In a method step 207, a corresponding adjustment of the coolant delivery devices of the cooling section takes place in the above manner, so that the desired final state of the sheet is achieved.

FIG. 4 shows a flowchart, which takes into account a limit temperature in a determination of a coolant delivery for a coolant delivery device. The consideration of a Such a limit temperature is therefore very advantageous because - depending on the coolant used - the cooling effect depends largely on the coolant behavior. The behavior of the coolant may change, for example, due to the temperature of the sheet.

When using water, it can be observed that, for example, at temperatures of the sheet surface below 350 ° C, the behavior of the cooling water changes. It comes to the Leidenfrosteffekt. This requires that especially on the top of the belt, the cooling effect of the water and thus the cooling of the sheet is hardly to control. On the bottom, the effect is not so strong, because there excess coolant can easily fall off the surface. On the other hand, a high cooling capacity, i. a high amount of coolant per unit of time may be required to achieve a desired state of the sheet.

However, this means that significantly more heat is dissipated from the surface than can flow from the interior of the sheet. There is a strong cooling on the surface of the sheet in conjunction with a high temperature gradient in the thickness direction of the sheet. If it falls below a critical surface temperature, this usually leads to an unevenness of the sheet. Often, this unplane sheet is to be regarded as a production committee and no longer usable. Furthermore, there is a risk that system components will be damaged.

In order to avoid this, the coolant delivery can take place taking into account a limit temperature, which may not be exceeded during cooling, at least not on the upper side of the sheet, possibly not on the underside of the sheet metal.

In a method step 300, the temperature of the top side of the sheet metal and / or the temperature of the bottom side of the sheet are determined. This can be done model-based as described above or by means of a measurement.

The determination of the coolant delivery can be carried out according to any method, preferably according to one of the above-described methods. This happens according to FIG. 4 in a method step 301.

In a method step 302, a surface temperature is pre-calculated, which occurs when the amount of coolant per unit time calculated according to method step 301 is applied to the surface of the sheet or sheet metal section.

Compliance with the limit temperature is checked in a method step 303.

If the temperature of the sheet-metal surface which adjusts itself due to the application of the coolant falls below the limit temperature, then the cooling capacity is redistributed or reduced, for example, to downstream coolant-discharging devices in a mass flow direction.

Subsequently, a coolant discharge is again determined on the basis of the redistributed or reduced cooling capacity, according to method step 301. This results in a new surface temperature, which is compared with the limit temperature. If this continues to fall, cooling capacity is redistributed or reduced until the limit temperature is maintained.

In the redistribution or reduction of cooling power, the temperature of the sheet is preferably included, and determines how the cooling capacity of the subsequent coolant delivery devices is set to, for example, dissipate a desired heat flow, comply with the limit temperature and to achieve the desired final state.

The redistribution of the cooling capacity on subsequent coolant delivery devices on the one hand ensures compliance the limit temperature, on the other hand reaching the target state of the sheet after passing through the cooling.

The compliance check may be successively, i. be done separately for each coolant delivery device separately, or be calculated for the entire cooling line in total.

In a method step 305, the coolant deliveries determined in accordance with the above method are set in the cooling section.

Preferably, this method becomes online, i. performed during the cooling of heavy plate, so that in real time the cooling process is optimized and accordingly no waste is generated by falling below the limit temperature.

Alternatively, a coolant delivery, in particular quantity of coolant to be dispensed per unit of time, is preferably already determined before the sheet enters the cooling section so that the limit temperature is already taken into account and is not undershot. This is less time consuming because no control loops are required. The calculated coolant delivery is then timed in the correct time during the passage of the sheet through the cooling section.

Claims (14)

Method for cooling a sheet (B) by means of a cooling section (1), the cooling section (1) having a plurality of coolant delivery devices (2) for cooling a sheet metal upper side (O) and a plurality of coolant delivery devices (2) for cooling a sheet metal underside (U) wherein by means of the cooling a predetermined target state of the sheet (B) at a reference point at and / or after exiting the cooling section (1) is achieved, wherein a coolant delivery for a first and a second coolant delivery device (2) is determined, the the first and the second coolant delivery device (2) are arranged opposite one another relative to the metal sheet (B),
characterized in that the determination of the coolant delivery for the first and second coolant delivery device (2) based on a predetermined dissipated heat flow from the respective coolant delivery device (2) facing sheet side (O, U), wherein for each dissipated heat flow, a temperature, in particular surface temperature (To, Tu), the respective sheet side (O, U) is taken into account. Method according to claim 1,
characterized in that a ratio of dissipating heat flow from the top side of the sheet metal (O) to the underside of the sheet metal (U) is set as a function of a planarity of the sheet (B), in particular when entering the cooling section (1). Method according to claim 2,
characterized in that in a plan, in particular a plan in the cooling section (1) incoming sheet (B), the ratio is substantially equal to one. Method according to claim 2,
characterized in that in an unplaned, in particular a unplan in the cooling section (1) incoming sheet (B), the ratio is adjusted such that the unevenness of the sheet after passing through the cooling section relative to the unevenness of the sheet (B) before passing through the cooling section (1) is reduced. Method according to one of the preceding claims,
characterized in that the determination of the coolant delivery the first and second coolant delivery device (2) based on the equation: $$\begin{array}{c}0=x\cdot j_{\mathit{above}}-\left(1-x\right)\cdot j_{\mathit{below}}\\ \hfill j_{\mathit{ges}}=j_{\mathit{above}}+j_{\mathit{below}}\end{array}$$

takes place, where
x: a predeterminable factor between 0 and 1,
J _above : a dissipated heat flow from the top of the sheet,
J _down : a heat flow to be dissipated from the bottom of the sheet, and
J _ges : a total heat flow to be dissipated and specified. Method according to claim 1,
characterized in that for at least one of the coolant delivery devices (2) the coolant delivery is determined independently of the coolant delivery of another coolant delivery device (2), in particular a relative to the sheet opposite coolant delivery device. Method according to claim 6,
characterized in that the determination is made such that the sheet (2) substantially parallel to the top (O) or bottom (U) is virtually divided into a first sheet and a second sheet, wherein the coolant delivery separately for the first and the second sheet is determined, with the respective determination a Heat exchange between the first sheet and the second sheet is disregarded. Method according to claim 7,
characterized in that for the first sheet and the second sheet each an individual time course of an energetic state of the sheet (B) descriptive size is determined, based determined by a dissipated heat flow for each sheet top (O) and the bottom surface (U) becomes. Method according to one of the preceding claims,
characterized in that is taken into account in the determination of the coolant delivery that during the passage of the cooling section (1) the temperature of the sheet top (O) and / or the temperature of the sheet bottom (U) always greater than or equal to a predetermined limit temperature, in particular 350 ° C, is. Method for cooling a sheet (B) by means of a cooling section (1), wherein the cooling section (1) has a plurality of coolant delivery devices (2) for cooling a sheet metal top and a plurality of coolant delivery devices (2) for cooling a sheet metal bottom, wherein by means of cooling a predetermined target state of the sheet (B) is achieved at least at and / or after leaving the cooling section, wherein a coolant delivery for at least one of the coolant delivery device (2) is determined,
characterized in that in determining the coolant delivery for at least one of the coolant delivery devices (2) is taken into account that that sheet side (O, U), which this coolant delivery device (2) faces, in particular during the implementation of the cooling, always a temperature greater or equal to a predetermined limit temperature. Control and / or regulating device (10) for a cooling line (1), with a machine-readable program code (12) which contains control commands, which the control and / or regulating device (10) carries out during execution of the method according to one of the preceding claims cause. Machine-readable program code (12) for a control and / or regulating device (10) for a cooling line (1), the program code having control commands which the control and / or regulating device (10) for carrying out the method according to one of claims 1 to 10 cause. A storage medium (11) having a machine-readable program code stored thereon according to claim 12. Cooling section (1) for cooling sheet metal (B), wherein the cooling section (1) has a plurality of coolant discharge means (2) for cooling a sheet metal top (O) and a plurality of coolant delivery means (2) for cooling a sheet metal underside (U) a control and / or regulating device (10) according to claim 11, wherein the coolant discharge means (2) are operatively connected to the control and / or regulating device (10) and are controllable and / or controllable therewith.

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