EP2817425B1 - Cooling control - Google Patents

Description

The present invention relates to a method for controlling a cooling of a material with a coolant, a computer program product for carrying out such a method, a control device for controlling a cooling of a material with a coolant, and a cooling section of a rolling mill, comprising such a control device.

For cooling metal strips, in particular steel strips, it is known to apply to these large amounts of water as a coolant. In a cooling section, the coolant flow and thus the cooling intensity must be regulated so that the desired structure of the material to be cooled is determined with high precision.

DD 213 853 A1 describes a control device for controlling a water supply in a water cooling section, which is operated to cool a rolling stock. The control device comprises flow meter and control valves in supply lines to cooling nozzles, which are connected to a control element of a computer system in which, depending on the type of rolling stock one of several deposited cooling control programs is processed (EDV = electronic data processing).

DE 101 37 596 A1 describes a method for cooling workpieces, in particular steel rolled products. The pressure of the cooling water is adjusted by an adjustment of pressure control valves. In the process, it is constantly checked whether an impermissible deviation of measured actual pressure values from desired pressure values exists and, if appropriate, a regulation of the pressure values is carried out.

DE 10 2007 046 279 A1 a method for a cooling line with centralized detection of valve characteristics.

Such pressure control loops are constantly disturbed by changes in the desired amount of water to the valves of the cooling section. For the pressure control loop thus constantly changes the behavior of the controlled system. Conversely, all flow control loops are disturbed by pressure fluctuations. Therefore, such regulations of a cooling line are relatively slow. Particularly disadvantageous occurs this disadvantage in an intensive cooling, that is, in the case of high water demand at a water pressure greater than 1 bar. Such a high water pressure can not be provided alone with a high tank, so that the operation of the intensive cooling and a water pump of water management is no longer possible decoupled.

It is an object of the present invention to provide an improved cooling of a material with a coolant.

The object is achieved according to claim 1 by a method for controlling a cooling of a material with a coolant, wherein a supply of the coolant to the material is controlled by at least one actuator which is adjustable in two or more different positions, wherein the actuator is an actuator Characteristic map is assigned, which indicates a relationship between a coolant flow, a pressure of the coolant and a position of the actuator, wherein at least one coolant pump, which is arranged in front of the at least one actuator arranged in the flow direction of the coolant, a pump characteristic field is assigned, which a relationship between a rotational speed of the pump, a pressure difference of the coolant, which exists between a suction pressure at an input side of the pump and an output pressure at an output side of the pump, and a coolant flow, and wherein a coolant flow is adjusted by the pressure difference is determined, from the pump characteristic field to the determined pressure difference and a desired coolant flow corresponding speed is determined, the pump is set to the determined speed, the pressure of the coolant in the flow direction of the coolant is detected before the at least one actuator , from the actuator characteristic field corresponding to the determined pressure value and the desired coolant flow Position is determined, and the actuator is set in the determined position. The object is further achieved by a computer program product for controlling the cooling of a material with a coolant, wherein a supply of the coolant to the material is controlled by at least one actuator which is adjustable in two or more different positions, wherein the actuator is an actuator characteristic field is assigned, which indicates a relationship between a coolant flow, a pressure of the coolant and a position of the actuator, wherein at least one coolant pump, which is arranged in front of the at least one actuator arranged in the flow direction of the coolant, a pump characteristic field is assigned, which has a relationship between a rotational speed of the pump, a pressure difference of the coolant, which exists between a suction pressure at an input side of the pump and an output pressure at an output side of the pump, and a coolant flow, and wherein the computer program product, if it by ei ne computing unit is carried out, performs the following method steps: determining a corresponding to a pressure difference of the coolant between the input side and the output side of the pump and a desired coolant flow speed of the pump from the pump characteristic field; Determining a position corresponding to a pressure value of the coolant, which was determined in the flow direction of the coolant in front of the at least one actuator, and the desired coolant flow corresponding position from the actuator characteristic field; Generating a signal which triggers an adjustment of the actuator in the determined position at an actuator associated with the actuator; and generating a signal that triggers an adjustment to the determined speed at the at least one coolant pump. The object is also achieved by a control device for controlling a cooling of a material with a coolant, comprising at least one storage unit, which is used to store an actuator characteristic field that has a relationship between a coolant flow, a pressure of the coolant and a position at least one of the actuator of characteristics associated actuator for controlling the supply of the coolant to the material, and for storing a pump characteristic field, the relationship between a rotational speed of the pump, a pressure difference of the refrigerant, between a suction pressure at an input side of the pump and an output pressure at an output side The pump prevails, and indicates a coolant flow, is formed, a processor unit, which is adapted from the stored actuator characteristic field corresponding to a determined pressure value of the coolant and a desired coolant flow position of the at least one actuator and from the stored pump Characteristic field to determine the corresponding to a determined pressure difference of the coolant between the input side and the output side of the pump and a desired coolant flow corresponding speed of the pump, and a signal unit which is adapted to a signal for adjusting the at least to send an actuator in the determined position to an actuator and to send a signal for setting the at least one coolant pump to the determined speed to a speed controller.

A common coolant is water, especially for the cooling of a material such as metal. With respect to a coolant, in the description of the invention, the terms "flow" and "flow" are used equivalently: they describe an amount of coolant passing per unit time through a given cross-sectional area. In this case, the cooling in the form of a water jet cooling, often referred to as laminar cooling, take place. Water jet cooling is a cooling of the material with one or more jets of water. The intensive cooling can be considered as a special case of laminar cooling. For intensive cooling in the sense of the present description, a high water requirement at a water pressure greater than 1 bar is characteristic. The water requirement of the intensive cooling can not be covered from a pure water tank, so that the operation of the intensive cooling - in the case of water as a coolant - coupled with a water pump of the water industry. The valves of the intensive cooling are preferably continuously adjustable, ie, the amounts of water are continuously variable to allow accurate metering of the cooling capacity.

According to the invention, no flow control circuits are constructed, but the actuators of a coolant run are controlled directly. Furthermore, no pressure control loop is established for the amount of coolant to be supplied to the cooling. The present invention is based on the finding that a high setting speed of a required coolant flow, z. B. a cooling water flow in a cooling line, can only be achieved by a controller, whereas a conventional scheme is too slow and too susceptible to failure, especially under the conditions of intensive cooling.

Preferably, the procedure is as follows: Each actuator, z. B. in the form of a control valve or a valve, a first actuator characteristic field k = f (w, p) is assigned, which maps the input quantities coolant flow w and pressure p of the coolant to an actuator position k and from a desired coolant flow w a direct determination of a corresponding actuator position k allows. This characteristic field is either previously known or is determined at least once by "Auslitern" of the actuator. By "venting" is meant an experimental determination of the flow through the actuator as a function of the position of the valve and the pressure of the coolant. To calibrate the actuator characteristic field f (w, p) flow measurements can be made.

Alternatively, a second actuator characteristic field w = g (k, p) can be stored, which maps the input variables actuator position k and pressure p of the coolant to a coolant flow w. It is also possible that alternatively a third actuator characteristic field p = h (k, w) is stored, that the input variables actuator position k and coolant flow w to a pressure p of the coolant images.

A process computer controls the actuators using the associated characteristic fields such that the required coolant flow flows through each actuator. For this purpose, the actual pressure p is detected, inserted into the characteristic field of each actuator, and each desired coolant flow w is mapped to a corresponding desired actuator position k. Alternatively, the target pressure is used instead of the actual pressure in the characteristic field.

Tests have shown that actuators designed as dampers can be moved from 0% to 100% of their opening degree in 2 s and from 20% to 80% of their opening degree in 1 s, and moreover, the pump can be stopped in less than 1 s from standstill Maximum speed can be brought. As a result, a rapid adjustment of the coolant flow in each coolant inlet to the material and an even faster adjustment of the coolant flow to supply the intensive cooling is possible, even if the coolant to the intensive cooling only over a long supply line, z. B. over a length in the range of 100 to 200 m, zoom must be transported.

With the present invention, it is possible to use a large amount of coolant, as z. B. in an intensive cooling a cooling line of a rolling mill is required, for example, a cooling water amount of about 150 m ^{3 of} water, sufficiently fast to accelerate, with the entry of the material to be cooled, for. As a metal strip, in the cooling line in a very short time, z. B. on a time scale of typically 1 s to build a stable flow of coolant. Even with thin metal strips, which are transported through the cooling line at a speed of approx. 10 m / s, the length of insufficiently cooled material remains smaller than 10 m. For a laminar flow cooling line, this value is of the same order of magnitude.

• Der benötigte Kühlmittelstrom kann genau zum gewünschten Zeitpunkt, z. B. beim Eintritt eines Materialbandes in die Kühlstraße, bereitgestellt werden. Umgekehrt kann der Kühlmittelstrom entsprechend schnell genau zum gewünschten Zeitpunkt, z. B. beim Austritt eines Materialbandes aus der Kühlstraße, reduziert werden.
• Eine hohe Regeldynamik wird auch während des Bandlaufs am Anlagenlimit erreicht; damit ist auch im Falle einer Intensivkühlung eine genaue Einstellung der Haspeltemperatur möglich, analog wie bei einer Laminarkühlung. Im Falle einer Intensivkühlung verringert sich also gegenüber einer Laminarkühlung die Genauigkeit der Haspeltemperatur nicht.
• Ein dynamischer Betrieb ist sowohl unter Hochdruck als auch unter Niederdruck des Kühlmittels möglich. Wird ein großer Kühlmittelstrom benötigt, kann der Solldruck angehoben werden (= Hochdruckbetrieb). Für Anwendungen, für die lediglich ein geringerer Kühlmittelstrom benötigt wird, kann man als Solldruck den Versorgungsdruck p_saug der Pumpe wählen (= Niederdruckbetrieb). Die Pumpendrehzahl kann dabei so gewählt werden, dass die Pumpe einfach nur wie eine Wasseruhr mitdreht, ohne den Versorgungsdruck der Intensivkühlung selbst zu verändern.
• Ein kontinuierlicher Wechsel zwischen einem Niederdruckbetrieb und einem Hochdruckbetrieb, auch während eines laufenden Kühlprozesses, ist möglich. Dadurch ist eine große Flexibilität in den Kühlverfahren, z. B. in der Produktion in einem Stahlwerk, gewährleistet.
• Auf eine mit hohen Kosten verbundene dynamische Durchflussmessung mithilfe einer Messeinrichtung vor jedem Stellglied, z. B. jedem Ventil, der Intensivkühlung kann verzichtet werden. Damit kann außerdem auf eine ausreichend lang ausgelegte, geradlinige Beruhigungsstrecke verzichtet werden, die im Falle einer Durchflussmessung zusätzlich zu einer Messeinrichtung erforderlich ist und die Kühlanlage zusätzlich verteuert.
• Die Erfindung erlaubt eine Kühlung mit einem hohen Wirkungsgrad. Das gesamte Kühlmittel, das transportiert, insbesondere gepumpt wird, wird zur Kühlung, insbesondere zur Intensivkühlung, verwendet. Dabei kann der Energieverbrauch der Pumpe noch weiter dadurch reduziert werden, dass ein höherer Druck des Kühlmittels nur dann erzeugt wird, wenn dieser tatsächlich benötigt wird. Der Bedarf für einen Hochdruckbetrieb kann z. B. dadurch festgestellt werden, dass man Stellungen von Stellgliedern, z. B. Klappenstellungen von Ventilen, ermittelt und den Solldruck für die Pumpe erst dann anhebt, wenn die Stellung wenigstens eines Stellglieds eine bestimmte, als Grenzwert vorgegebene Öffnungsstellung überschreiten würde.
• Die Erfindung ist ein wesentlicher Baustein einer Anlage, die einen kombinierten, flexiblen Kühlbetrieb erlaubt, durch den die normale Produktion, z. B. in einem Stahlwerk, nicht gestört oder beeinträchtigt wird.

Cooling with the control of actuators according to the invention thus has the following advantages:

• The required coolant flow can be exactly at the desired time, for. B. upon entry of a strip of material in the cooling line, are provided. Conversely, the coolant flow can be correspondingly fast exactly at the desired time, for. B. at the exit of a strip of material from the cooling line can be reduced.
• High control dynamics are also achieved during the tape run at the system limit; Thus, even in the case of intensive cooling accurate adjustment of the reel temperature is possible, similar to a laminar cooling. In the case of intensive cooling, the accuracy of the reel temperature is therefore not reduced in comparison with laminar cooling.
• Dynamic operation is possible both under high pressure and under low pressure of the coolant. If a large coolant flow is required, the setpoint pressure can be raised (= high pressure operation). For applications for which only a lower coolant flow is required, you can _suck the supply pressure p as the set pressure of the pump select (= low-pressure operation). The pump speed can be chosen so that the pump simply rotates just like a water meter, without changing the supply pressure of the intensive cooling itself.
• A continuous change between a low-pressure operation and a high-pressure operation, even during a running cooling process, is possible. As a result, a great deal of flexibility in the cooling process, for. B. in the production in a steel mill, guaranteed.
• High-cost dynamic flow measurement using a measuring device in front of each actuator, eg B. each valve, the intensive cooling can be omitted. This can also be dispensed with a sufficiently long, straight calming section, which is required in the case of flow measurement in addition to a measuring device and the cooling system more expensive.
• The invention allows cooling with a high efficiency. The entire coolant that is transported, in particular pumped, is used for cooling, in particular for intensive cooling. In this case, the energy consumption of the pump can be further reduced by the fact that a higher pressure of the coolant is only generated when it is actually needed. The need for a high-pressure operation can z. B. be found that one positions of actuators, z. B. flap positions of valves, determined and the target pressure for the pump only raises when the position of at least one actuator would exceed a certain, predetermined limit value opening position.
• The invention is an essential component of a system that allows a combined, flexible cooling operation, through the normal production, for. B. in a steel mill, is not disturbed or impaired.

Advantageous embodiments and modifications of the invention will become apparent from the dependent claims. In this case, the inventive method can also be developed according to the dependent device claims, and vice versa.

According to a preferred embodiment of the invention, the at least one actuator is adjusted continuously in the determined position. Preferably, the at least one actuator is a continuously adjustable actuator. A continuous adjustment or adjustability of the at least one actuator means that the at least one actuator is continuously adjusted in the determined position. In the continuously variable actuator, it may, for. B. act a valve or a control valve.

A control method using continuously variable actuators is not significantly more expensive than the conventional equipment of cooling sections with simple switching valves. In this case, a high tank decouples the control of the water management from the control of the valves of the valves. Such a control avoids the switching jumps occurring in switching valves in temperature and is therefore particularly suitable for a model-predictive control of the temporal Abkühlverlaufs in the cooling section.

The development of the invention provides that the at least one coolant pump is assigned a pump characteristic field n = q (w, Δp), which has a pump speed n as a function of a coolant flow w and a pressure difference Δp of the coolant between a suction pressure on an input side the pump and an outlet pressure at an outlet side of the pump, indicating that the suction pressure of the coolant is detected, and the pump is operated at a speed which is determined to the pressure difference and a target coolant flow from the pump characteristic field.

Alternatively, it is also possible for the at least one coolant pump to be assigned a second pump characteristic field w = r (n, Δp) which determines the coolant flow w as a function of the pump rotational speed n and the pressure difference Δp of the coolant which exists between the suction pressure at the Input side of the pump and the outlet pressure at the outlet side of the pump. Alternatively, it is also possible that the at least one coolant pump, a third pump characteristic field Δp = s (n, w) is assigned, which is the pressure difference .DELTA.p of the refrigerant between the suction pressure at the input side of the pump and the output pressure at the output side of the Pump prevails as a function s of the pump speed n and the coolant flow w indicates.

The coolant pump, z. As a water pump that supplies the cooling device with coolant, a pump characteristic field n = q (w, pp _suction ) can be assigned. In this case, n denotes the target pump speed, w is the coolant flow to be conveyed, p is the pressure at the outlet side of the pump and p _sucks the suction pressure on the inlet side of the pump. In this case, w must be the sum of the coolant flows of all the actuators of the cooling, plus any further existing customers who receive coolant from the cooling pump. The pump is controlled by a process computer so that it runs at a speed n, which emerges at the onset of the desired coolant flow w and a target pressure increase pp _suction into the pump characteristic field. For this purpose, the suction pressure is advantageously measured on the input side of the pump. Alternatively, an estimate may also be used, e.g. B. calculated from the height difference between the location of the pump and the coolant level in a coolant tank, with which the suction side of the pump is supplied. Alternatively, a desired value of another control device can be used, which supplies the coolant to the pump on the suction side.

It is advantageous if a control device not only the actuators, but also the pumps, for. B. for the high tank, controls because the control device, the coolant flows to be provided are already known in advance. This can be provided in the form of a so-called intelligent coolant management: In this case, controls the control device in addition to actuators, for. B. the valves of the valves, the entire water management across and "knows" all water consumers in the system, d. H. takes into account their water consumption on the basis of previously collected and / or current consumption values. In particular, the control device also controls the intensive cooling.

The pump is preferably frequency-controlled with a converter. The characteristic field of the pump is either previously known or is determined at least once by Auslitern the pump.

It is advantageous that the position of the at least one actuator and the speed for operating the at least one coolant pump in one step as a common Setpoint set is determined, wherein the pressure of the coolant before the at least one actuator is identical to the output pressure at the output side of the pump.

A process computer determines the setpoint speed of the pump and the positions of the actuators, eg. As the positions of valves or flaps, preferably in one step as a common setpoint set (= cross-control). So there is no need to wait until the actual refrigerant pressure is actually present when the actuators are actuated, and vice versa. Furthermore, it is avoided that the pump can be damaged by operation in an impermissible area. Such damage could occur if a separate pump control due to an earlier estimate of the coolant demand, the pump in the sense of feedforward starts, but the process computer does not open the actuators as expected, because there is a fault and the setpoint set for the actuators does not arrive there. With a common setpoint set, however, consistency is always ensured.

It is also possible that the suction pressure of the refrigerant at the input side of the pump is determined by a measurement or an estimation.

According to one embodiment, the actuator characteristic field is adapted by determining the pressure of the coolant, in particular measured, the position of the actuator is determined from the actuator characteristic field of the determined values, ie pressure and position, corresponding coolant flow is determined, the coolant flow determined from the actuator characteristic field is compared with a measured coolant flow and the actuator characteristic field is changed so that the coolant flow determined from the actuator characteristic field coincides with the measured coolant flow.

According to one embodiment, the actuator characteristic field, which is given in a second form w = g (k _i , p), for adapting the actuator characteristic field by means of approach functions, in the form g (k _i , p) = Σ _j c _j g _j (k _i , p), wherein the gain factors c _j are chosen to be appropriate for the respectively associated approach functions g _j (k _i , p). The usual disadvantage of a control that the set coolant amounts are more inaccurate than in a control, can be compensated by an adaptation of the actuator characteristic field using the factors c _j .

If the recognition functions are local, e.g. For example, if they are B-splines that are different only in an environment around the zero evolution point, the adaptation converges very fast, because then the map is improved only in the vicinity of the current measurement and points of the map farther away from the current measurement are not changed, in particular not be degraded.

In this procedure, it is still necessary to check during or after the adaptation, the characteristic field, whether it is still strictly monotonically increasing. This can z. For example, if inaccurate measured values are detected or the initial characteristic field is very inaccurate and the adaptation must make major corrections. If the characteristic field is not strictly monotonically increasing after adaptation, the adaptation of the respective factor c _j must be reduced or reversed. Otherwise, the process computer from a given desired coolant flow w _soll and a pressure p no longer uniquely determined by dissolving the function w _soll = g (k _i , p) after k _i a position k _{i of} the actuator.

It is also possible, in an improved embodiment, to store the actuator characteristic field in a first characteristic curve k = f (w, p), which enables a direct determination of the actuator position k _i from a desired coolant flow w. Namely, it is possible in this case, in particular, the characteristic field stored in the first characteristic form k = f (w, p) directly adapt. For this purpose, the pressure p of the coolant and the coolant flow w of the coolant are determined, in particular measured, determined from the actuator characteristic field to the determined values, ie pressure and coolant flow, corresponding position of the actuator, the determined from the actuator characteristic field position of the actuator compared with a measured position of the actuator and the actuator characteristic field changed so that the determined from the actuator characteristic field position of the actuator coincides with the measured position of the actuator.

According to a preferred embodiment, the actuator characteristic field, which is given in the first form k = f (w, p), for adapting the actuator characteristic field by means of approach functions, in the form f (w, p) = Σ _j a _j f _j (w, p), where the gain factors a _j are chosen to be appropriate for the respectively associated approach functions f _j (w, p). In this case, the process computer can directly determine the required position k of the actuator from the pressure p and the desired water quantity W _soll according to k _i = f (w _soll , p), without first having to invert the characteristic field. It is particularly advantageous in this approach that when adapting the coefficients a _j by the adaptation does not need to be checked whether the characteristic field is still strictly monotonically increasing. Another advantage of this approach is that the computational effort involved in solving a nonlinear function for a variable is eliminated.

According to an advantageous embodiment of the invention, the pump characteristic field is adapted by determining the pressure difference and the flow of the coolant, from the pump characteristic field corresponding to the determined values pump speed is determined, the pump speed determined from the pump characteristic curve pump speed with a measured Pump speed is compared and the pump characteristic field is changed so that the determined from the pump characteristic field Pump speed coincides with the measured pump speed.

It is advantageous that the pump characteristic field, which is given in a first form n = q (w, pp _suction ), is represented for adaptation of the pump characteristic field by means of batch functions, in the form q (w, pp _suction ) = Σ _j b _j q _j (w, pp _suction), the gain factors b _j suited to the particular associated approach functions q _j (w, pp _suction) can be selected.

The usual disadvantage of a control that the set coolant amounts are more inaccurate than in a control, can be compensated by an adaptation of the pump characteristic field using the factors b _j .

It is also possible to _store the pump characteristic field in a second form w = r (n, pp _suction ). But then the pump characteristic field must be resolved to n, if the nominal speed of the pump is to be determined. This is particularly disadvantageous when the pump characteristic field will be adapted: If one wishes to pump characteristic field in the form w = r adapt (n, pp _suction) is not ensured that can be uniquely solved for the pump speed. Therefore, a malfunction can not be excluded in this case. The same applies if one represents the pump characteristic field in a third form Δp = pp _suction = s (n, w). Even then, the pump characteristic field must be resolved to n if the desired speed of the pump is to be determined.

According to a preferred embodiment, the control device comprises the at least one actuator, which is preferably designed as a valve or a control valve.

A further preferred embodiment of the invention is a cooling section of a rolling mill, comprising an above-described Control device for controlling the cooling of a material in the cooling section.

According to a preferred embodiment, the cooling section comprises an intensive cooling section and / or a laminar cooling section. Thus, the present invention can be used both for an intensive cooling section and for a laminar cooling section. The invention is not limited to intensive cooling. It is also possible to control a zone of a normal laminar cooling path with it if the actuators in this zone are continuously adjustable. In particular, the invention can also be carried out when the variable-speed pump is supplied directly from a coolant supply network with coolant, for. B. is supplied directly from the water supply network with water ,, d. H. without a high tank arranged therebetween and acting as a buffer.

With intensive cooling, a section of the cooling section with a particularly high cooling capacity, high cooling rates can be realized. An advantage of intensive cooling, which is also known as a "power cooling" method, is that even higher and high strength steels in a wide range of thicknesses even faster, d. H. with a higher cooling rate, can be cooled. This enables the high-precision and efficient production of additional steel grades, in particular steels with higher strengths than before.

An intensive cooling section may be particularly useful in the forward section of the cooling section to inhibit grain growth in a material material, accelerate the phase transformation of a material, and thereby increase the overall strength of the material. In certain cases, such intensive cooling but also be useful behind the roughing or be installed at other locations of the cooling section. It is also possible to arrange intensive cooling beams between stands of the finishing train.

For example, a strip cooling system for a hot rolling mill may include a pre-strip and a finish strip cooling, consisting of an intensive and a laminar cooling section. The pre-strip cooling can be installed behind a roughing stand in the area of the intermediate roller table. It provides temperature compensation over the entire length and width of the sliver before it arrives on the finishing train. At the exit of the finishing train an intensive cooling section can be arranged. Immediately behind the intensive cooling, a laminar cooling section can be positioned. Usually both systems are operated together.

Of particular importance for the application in the cooling section is a sufficiently large adjustment range of the cooling device towards low water volumes in order to use the intensive cooling as a normal laminar cooling can, when materials are produced, in which only low cooling rates may be applied. Since materials with high cooling performance are produced in the production mixed with standard products that require lower cooling capacities, the rapid change of the cooling capacity that is possible with the invention is very advantageous. The invention thus obviates the very unfavorable solution which requires pushing large pipes with each change in the amount of cooling water, such as a change from a high pressure operation to a low pressure operation by switching off booster pumps and activating a supply from a water tank for the low pressure operation. Such solutions can only z. B. during a roll change or another longer downtime, but not during production.

Another advantage of the invention is the dynamic change of large amounts of water when the belt is run in or when the belt leaves the intensive cooling again. A strip in the intensive cooling may require a cooling water amount in the range of 8000 m ³ / h. The intensive cooling can usually not be activated before the arrival of the tape in the cooling section, because with thinner tapes acting on the tape by the water forces can cause the tape to fly up. On the other hand, thicker tapes often require a warmer tape on the first tapes so that the reel can grip the tape and bend around the mandrel. This means that especially at the belt inlet and the belt outlet large amounts of water must be changed very dynamically. The present invention provides just this dynamic.

Furthermore, the present invention makes it possible to accurately meter the large amounts of water used in intensive cooling. The accuracy of the amount of water applied to the intensive cooling is critical to the accuracy of the reel temperature that can be achieved. This is particularly important in order not to let the advantage of high cooling rates, the increase in strength, turn into the disadvantage of poor reproducibility of the material properties. By achieving the accuracy of the coolant flow achievable with the invention, deterioration of reel temperature accuracy over standard laminar cooling can be avoided by operating the intensive cooling at low cooling power to produce standard products. However, the invention also avoids a significant deterioration of the reel temperature accuracy when operating at high cooling capacities.

Preferably, the present invention provides an application of a control method of coolant actuators according to a characteristic field and preferably additionally a coolant pump according to a characteristic field on a cooling path of a metalworking line, in particular in a hot strip mill, but the invention can also be applied in particular in a heavy plate mill , in which thick sheets are produced and must be cooled.

Fig. 1

eine Metallverarbeitungsstraße;

Fig. 2

ein erstes Stellglied-Kennlinienfeld;

Fig. 3

ein zweites Stellglied-Kennlinienfeld;

Fig. 4

ein erstes Pumpen-Kennlinienfeld;

Fig. 5

ein zweites Pumpen-Kennlinienfeld; und

Fig. 6

ein Schema einer Steuerung eines Kühlmittelstroms.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which will be described in detail in conjunction with the drawings. It shows

Fig. 1

a metal processing line;

Fig. 2

a first actuator characteristic field;

Fig. 3

a second actuator characteristic field;

Fig. 4

a first pump characteristic field;

Fig. 5

a second pump characteristic field; and

Fig. 6

a scheme of control of a coolant flow.

Fig. 1 shows a metalworking line 1, which is referred to here as a cooling line 2, also referred to as a cooling section. The cooling line 2 is connected downstream of a production line whose last rolling stand is indicated at 3. A material 4, which is designed here as a metal to be processed 4 in strip form, first passes through the production line and then the cooling section 2, whereupon it is for removal or caching until further processing on a reel 5, which is downstream of the cooling section 2 , is wound up.

The metalworking line 1 can z. B. be arranged in a hot strip mill of a steelworks.

The cooling section 2 comprises actuators 6, with which a defined coolant flow can be discharged onto the material 4, a coolant inlet 13, through which coolant from a coolant reservoir, for. As a water supply network or a high tank, are supplied to the actuators 6 can, and a switched into the coolant inlet 13 coolant pump 20, with which the pressure of the coolant at an output side 20a of the pump 20 against a pressure of the coolant at an input side 20e of the pump 20 can be changed. In this case, the actuators include 6 flaps and valves with which serving as a coolant water via cooling bars 14 on the band-shaped metal 4 can be applied, for. B. aufspritzbar, is to cool it.

Although in Fig. 1 However, only a few actuators 6 are shown, the cooling section 2 may include a large number of such actuators 6. All actuators can be supplied with coolant via the same pump. It is also possible that there are two or more pumps, each providing one or more actuators with coolant.

The cooling section 2 further comprises a control device 7, which in Fig. 1 is indicated schematically. The control device 7 comprises a computing unit 8, a memory unit 12, an input device 9 for inputting data into the computing unit 8 and a display device 10 for displaying data. The arithmetic unit 8 controls via control lines 15, the actuators 6, z. As valves, nozzles or flaps, according to an actuator characteristic map 11w. In addition, the arithmetic unit 8 controls the coolant pump 20 via control lines 15 in accordance with a pump characteristic field 11n.

In order to reduce the temperature of the material 4 targeted, the actuators 6 are individually controlled and thus the flow rates of the chilled beam 14 separately regulated. A high tank feeds the cooling bars 14 with coolant, in particular with water, via the coolant inlet 13. At particularly high cooling rates, the pump 20 can be switched on. In this way, the cooling of the respective produced material, for. As the steel grade, adapt.

It is possible that the control device 7 in a manual operating mode at least partially via the input device 9 can be changed by an operator, so that z. B. the actuators 6 can be controlled in groups or separately. The manual controllability does not have to be permanently provided, it is just as conceivable that it is possible to switch between an automatic operating mode and a manual operating mode.

In addition, the arithmetic unit 8 receives further information about the state of the cooling section 2 or the metal 4. In addition to measured values on the pressure of the coolant at different points of the coolant inlet 13 of the arithmetic unit 8 primary data of the metal 4, the metal 4 and its state when entering into describe the cooling section 2, z. As the chemical composition of the metal, the speed v and the temperature T of the metal supplied.

One or more actuator characteristic fields 11w and one or more pump characteristic fields 11n are stored in the memory unit 12. Depending on the type of actuator or the pump one of the stored characteristic fields is assigned to the respective component. Preferably, two or more actuators or pumps of the same type are assigned the same characteristic field; This achieves faster convergence in the cooling system, and cooling control can be faster. But it is also possible that each actuator 6 and each pump 20 is assigned its own characteristic field 11w or 11n.

Fig. 2 shows a diagrammatic representation of a first actuator characteristic field 11k, the w is the dependence of the coolant pressure P and the flow of coolant by an actuator 6 from each other with the position of k _i of the actuator 6 describes as a parameter: k = f (w, p). The coolant pressure p increases along the p-axis (= y-axis), starting at p = 0. The coolant flow w increases along the w-axis (= x-axis). The parameter curves k _i define the mutual dependence between the coolant pressure p and the coolant flow w for different positions k _{i of} the actuator 6; at k = 10% the opening degree of the actuator is 10 percent, at k = 90% the opening degree of the actuator is 90 percent. The actuator characteristics map 11k may be stored in a memory unit of a controller.

The actuator characteristic field 11k in the first characteristic form k = f (w, p) has the advantage that a direct determination of the actuator position k _i from a desired coolant flow w _{i, soll is} possible: A process computer of the control device detects for each actuator, the actual pressure p _i , this sets in the actuator associated with each actuator characteristic map 11k and determined based on the actuator characteristic field 11k to each desired coolant flow w _{i, should} a corresponding desired actuator position k _{i of} an actuator. Thereafter, the process computer controls the actuators accordingly. For this purpose, a signal unit of a control device sends a signal for setting the at least one actuator in the determined position k _i to an actuating unit, which serves to adjust the actuator.

Fig. 3 shows a graphical representation of another, second actuator characteristic field 11w, which describes the dependence of the position k of an actuator 6 and the coolant pressure p from each other with the coolant flow w as a parameter: w = g (k, p). The coolant pressure p increases along the p-axis (= y-axis), starting at p = 0. The position k _{i of} the actuator 6 increases along the k-axis (= x-axis); at k = 0 the opening degree of the actuator is 0 percent, at k = 100 the opening degree of the actuator is 100 percent. The parameter curves w define the mutual dependence between the coolant pressure p and the position k _{i of} an actuator for different coolant flows w.

The second actuator characteristic field 11w is used to determine a position k _{i of} an actuator 6, in which under a desired coolant flow p _i, a desired coolant flow, the desired coolant flow w _{i, soll} , results. Related to the in Fig. 1 2, the procedure is as follows: first, the pressure p _{i of} the coolant, as seen in the flow direction of the coolant between the coolant pump 20 and the actuator 6, is determined. This determination can be made by a pressure measurement or an estimate. Is from the actuator 6 associated actuator characteristic field 11w then the pressure value determined to the p _i and the desired coolant flow w _{i, soll} determined corresponding position k _i of the actuator. 6 Finally, the relevant actuator 6 is set in the determined position k _i .

If between the actual coolant flow, the z. B. is determined by a flow measurement of the coolant flow, and according to the actuator characteristic field 11w expected coolant flow w _{i, should} a difference occurs, which is above an allowable tolerance value, is preferably an adaptation of the actuator characteristic field 11w to the actual conditions carried out. For this purpose, the actuator characteristics field 11w, which is given in the form w = g (k, p), where w denotes the coolant flow, p the pressure of the coolant and k the position of the actuator, by means of attachment functions g _j (k, p) shown in the form of g (k, p) = Σ _j c _j f _j (k, p). The amplification factors c _j are suitably selected to the respective associated approach functions g _j (k, p) by the pressure p of the coolant is determined, in particular measured, is the position k of the actuator 6 is determined from it using the approach functions numerical values (= volume flows ) d _j = g _j (k, p) are determined, and using the numerical values d _j changes Δc _{j of} the gain factors c _j are chosen so that the determined coolant flow w _is approximated to the desired coolant flow w _soll and the changes .DELTA.c _{j of} the gain factors c _{j are} minimized.

Fig. 4 shows a diagrammatic representation of a pump characteristic field 12n which describes the dependence of the pressure difference Δp of the coolant pressures before and after the coolant pump 20 and the coolant flow w from each other with the rotational speed n of the coolant pump 20 as a parameter: n = q (w, Δp). The pressure difference Δp increases along the Δp-axis (= y-axis), starting at Δp = 0. The coolant flow w increases along the w-axis (= x-axis). The parameter curves n define the mutual dependence between the coolant pressure difference Δp and the coolant flow w for different rotational speeds n of the coolant pump 20.

The pump-12n characteristic field is used to determine a rotational speed n _i at which a desired coolant flow under a predetermined coolant pressure difference Dp, the target coolant flow w _{i, is intended} to result. Related to the in Fig. 1 2, the procedure is as follows: first, the suction pressure p _{suction of} the coolant, that is, the coolant pressure at the input side 20e of the pump 20, determined, and from the target pressure difference .DELTA.p _soll calculated. Subsequently, the pump speed n _{i is} determined from the pump characteristic field 12n to the calculated desired pressure difference Δp _soll and to a desired coolant flow w _i . Finally, the speed of the pump 20 is set to the determined value n _i .

If between the actual coolant flow, the z. B. is determined by a flow measurement of the coolant flow, and according to the pump characteristic field 12n expected coolant flow w _{i, should} a difference occurs, which is above an allowable tolerance value, is preferably an adaptation of the pump characteristic field 12n to the actual conditions carried out.

For this purpose, the pump characteristic field 12n, which is given in the form n = q (w, pp _suction ), where n is the pump speed, p the output pressure at the output side 20a of the pump 20, p _suction, the suction pressure at the input side 20e of the pump 20, and w denotes the coolant flow, represented by means of attachment functions, in the form q (w, pp _suction ) = Σ _j b _j q _j (w, pp _suction ). The amplification factors _j b _j (w, pp _suction) selected suitable to the respective corresponding basis functions q by the output pressure p of the refrigerant at the exit side 20a of the pump is determined, in particular measured is. From this, with the already known suction pressure p _{suction of} the coolant, ie the coolant pressure at the input side 20e of the pump 20, the pressure difference Δp of the coolant is determined. In addition, the coolant flow w _{i is} determined, preferably measured. From this, numerical values (= rotational speeds) e _j = q _j (w, pp _suction ) are determined by means of the approach functions and, using the numerical values e _j, changes Δb _{j of} the amplification factors b _j are selected such that the pump rotational speed expected according to the pump characteristic field 12 n the actual pump speed is approximated and the changes Δb _{j of} the gain factors b _{j are} minimized.

Fig. 5 shows a graphical representation of another, second pump characteristic field 12w, which describes the dependence of the pressure difference Ap of the coolant pressures before and after the coolant pump 20 and the pump speed n from each other with the coolant flow w as a parameter: w = r (n, Ap). The pressure difference Δp increases along the Δp-axis (= y-axis), starting at Δp = 0. The pump speed n increases along the n-axis (= x-axis). The parameter curves w define the mutual dependence between the coolant pressure difference Δp and the rotational speed n for different volume flows w of the coolant.

Fig. 6 shows a schematic representation of the control of the coolant flow to a material to be cooled 4. In a coolant inlet 13, z. Example in the form of a pipe, a pump 20 and subsequently a valve 6 are arranged in the flow direction of the coolant. In the flow direction of the coolant seen upstream of the pump 20, ie on the input side 20e of the pump 20, the coolant has a pressure which is referred to as the suction pressure p _intake. In the flow direction of the coolant seen by the pump 20, that is on the exit side 20a of the pump 20, the cooling means comprises a pressure simply referred to as p on which results on the generated by the pump 20 from the suction pressure change p _intake. The operation of the pump 20, in particular its speed n, is controlled by means of the pump characteristic field 12n. The flow rate of the valve 6, which is located downstream of the pump 20 when viewed in the flow direction of the coolant, is controlled by means of the actuator characteristic map 11k. The coolant flow w _{i of} the coolant to the material 4 can thus be precisely controlled by the pump 20 and the valve 6.

If there are no sources or sinks for the coolant between the pump 20 and the valve 6, as in Fig. 6 shown, the coolant flow w _i , which is pumped by the pump 20, the one which flows through the valve 6, ie w _i , valve = w _i , pump. Therefore, preferably, if the coolant flow w _i can not be determined, in particular measured, the actuator characteristics map 11k and the pump map 12n can be mutually adjusted to provide consistent results.

In addition, preferably, if the coolant flow w _i can not be determined, in particular can be measured, an adaptation with respect to the temperature of the material to be cooled, for. B. a metal part, take place. As a result, an error of the coolant flow w _{i can be} compensated or eliminated. If the temperature model is sufficiently known, it can be concluded that a certain coolant flow w _{i is} cooling by a certain temperature difference.

While the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims (14)

1. Method for controlling a cooling process for a material (4) by means of a coolant,
   wherein a supply (13) of the coolant to the material (4) is controlled by means of at least one actuator (6) which can be set to two or more different positions (k), wherein the actuator (6) is assigned an actuator characteristic curve set (11k, 11w) which specifies a relationship between a coolant flow (w), a pressure (p) of the coolant, and a position (k) of the actuator (6),
   wherein at least one coolant pump (20) which is arranged upstream of the at least one actuator (6), viewed in the flow direction of the coolant, is assigned a pump characteristic curve set (12n, 12w) which specifies a relationship between a rotational speed (n) of the pump (20), a pressure difference (Δp) of the coolant obtaining between a suction pressure (p_suction) at an inlet side (20e) of the pump (20) and an outlet pressure (p) at an outlet side (20a) of the pump (20), and a coolant flow (w), and
   wherein a coolant flow (w_i) is set in that the pressure difference (Δp) is ascertained, the rotational speed (n_i) corresponding to the ascertained pressure difference (Δp) and a target coolant flow (w_i, target) is ascertained from the pump characteristic curve set (11n), the pump (20) is set to the ascertained rotational speed (n_i), the pressure (p_i) of the coolant upstream of the at least one actuator (6), viewed in the flow direction of the coolant, is ascertained, the position (k_i) corresponding to the ascertained pressure value (p_i) and the target coolant flow (w_i, _target) is ascertained from the actuator characteristic curve set (11w), and the actuator (6) is set to the ascertained position (k_i).
2. Method according to claim 1, wherein the at least one actuator (6), which can be set to the two or more different positions (k) in a stepless manner, is continuously adjusted to the ascertained position (k_i).
3. Method according to one of the preceding claims, wherein the position (k_i) of the at least one actuator (6) and the rotational speed (n_i) for operating the at least one coolant pump (20) is ascertained in one step as a common target value set, wherein the pressure (p_i) of the coolant upstream of the at least one actuator (6) is identical to the outlet pressure (p) at the outlet side (20a) of the pump (20).
4. Method according to one of the preceding claims, wherein the suction pressure (p_suction) at the inlet side (20e) of the pump (20) is measured or estimated.
5. Method according to one of the preceding claims, wherein the actuator characteristic curve set (11k) is adapted in that the pressure (p_i) of the coolant is ascertained, in particular measured, the coolant flow (w_i) of the coolant is ascertained, in particular measured, the position of the actuator (6) corresponding to the ascertained values (w_i, p_i) is ascertained from the actuator characteristic curve set (11k), the position of the actuator (6) ascertained from the actuator characteristic curve set (11k) is compared with a measured position of the actuator (6), and the actuator characteristic curve set (11k) is modified such that the position of the actuator (6) ascertained from the actuator characteristic curve set (11k) corresponds to the measured position of the actuator (6).
6. Method according to claim 5,
   wherein the actuator characteristic curve set (11k), which is given in the form k = f(w, p), wherein w denotes the coolant flow, p the pressure of the coolant, and k the position of the actuator, is represented, for the purpose of adapting the actuator characteristic curve set (11k), by means of basis functions f_j (w, p), in the form f(w, p) = Σ_j a_j f_j (w, p), where the amplification factors a_j are suitably chosen in relation to the respective associated basis functions f_j (w, p).
7. Method according to one of the preceding claims, wherein the pump characteristic curve set (12n) is adapted in that the pressure difference (Δp) and the flow (w_i) of the coolant are ascertained, the pump speed (n) corresponding to the ascertained values (Δp, w_i) is ascertained from the pump characteristic curve set (12n), the pump speed ascertained from the pump characteristic curve set (12n) is compared with a measured pump speed, and the pump characteristic curve set (12n) is modified such that the pump speed ascertained from the pump characteristic curve set (12n) corresponds to the measured pump speed.
8. Method according to claim 7,
   wherein the pump characteristic curve set (12n), which is given in the form n = q(w, p-p_suction), wherein n denotes the pump speed, p the outlet pressure at the outlet side (20a) of the pump (20), p_suction the suction pressure at the inlet side (20e) of the pump (20), and w the coolant flow, is represented, for the purpose of adapting the pump characteristic curve set (12n), by means of basis functions, in the form q(p-p_suction, w) = Σ_j b_j q_j (w, p-p_suction), wherein the amplification factors b_j are suitably chosen in relation to the respective associated basis functions q(w, p-p_suction).
9. Computer program product for controlling the cooling process for a material (4) by means of a coolant,
   wherein a supply of the coolant to the material (4) is controlled by means of at least one actuator (6) which can be set to two or more different positions (k), wherein the actuator (6) is assigned an actuator characteristic curve set (11k, 11w) which specifies a relationship between a coolant flow (w), a pressure (p) of the coolant and a position (k) of the actuator (6),
   wherein at least one coolant pump (20) which is arranged upstream of the at least one actuator (6), viewed in the flow direction of the coolant, is assigned a pump characteristic curve set (12n, 12w) which specifies a relationship between a rotational speed (n) of the pump (20), a pressure difference (Δp) of the coolant obtaining between a suction pressure (p_suction) at an inlet side (20e) of the pump (20) and an outlet pressure (p) at an outlet side (20a) of the pump (20), and a coolant flow (w), and
   wherein the computer program product, when executed by means of a computing unit (8), performs the following method steps:

   - ascertaining a rotational speed (n_i) of the pump (20) corresponding to a pressure difference (Δp) of the coolant between the inlet side (20e) and the outlet side (20a) of the pump (20) and a target coolant flow (w_i, target) from the pump characteristic curve set (12n, 12w);

   - ascertaining a position (k_i) corresponding to a pressure value (p_i) of the coolant which was ascertained upstream of the at least one actuator (6), viewed in the flow direction of the coolant, and the target coolant flow (w_i) from the actuator characteristic curve set (11k, 11w);

   - generating a signal which triggers a setting of the actuator (6) to the ascertained position (k_i) at an actuating unit assigned to the actuator (6); and

   - generating a signal which triggers a setting to the ascertained rotational speed (n_i) at the at least one coolant pump (20).
10. Control device (7) for controlling a cooling process for a material (4) by means of a coolant, comprising

    - at least one memory unit (12) which is embodied for storing an actuator characteristic curve set (11k, 11w) which specifies a relationship between a coolant flow (w_i), a pressure (p) of the coolant and a position (k_i) of at least one actuator (6) assigned to the actuator characteristic curve set (w) for the purpose of controlling the supply of the coolant to the material (4), and for storing a pump characteristic curve set (12n, 12w) which specifies a relationship between a rotational speed (n) of the pump (20), a pressure difference (Δp) of the coolant obtaining between a suction pressure (p_suction) at an inlet side (20e) of the pump (20) and an outlet pressure (p) at an outlet side (20a) of the pump (20) and a coolant flow (w),

    - a processor unit (8) which is embodied to ascertain the position (k_i) of the at least one actuator (6) corresponding to an ascertained pressure value (p_i) of the coolant and a target coolant flow (w_i) from the stored actuator characteristic curve set (11k, 11w) and to ascertain the rotational speed (n_i) of the pump (20) corresponding to an ascertained pressure difference (Δp) of the coolant between the inlet side (20e) and the outlet side (20a) of the pump (20) and a target coolant flow (w_{i, target}) from the stored pump characteristic curve set (12n, 12w), and

    - a signal unit (22) which is embodied for sending a signal for setting the at least one actuator (6) to the ascertained position (k_i) to an actuating unit and for sending a signal for setting the at least one coolant pump (20) to the ascertained rotational speed (n_i) to a rotational speed governor.
11. Control device (7) according to claim 10,
    wherein the control device (7) comprises the at least one actuator (6), which is preferably embodied as a valve or a butterfly valve.
12. Control device (7) according to claim 11,
    wherein the at least one actuator (6) is continuously adjustable.
13. Cooling bed (2) of a metal processing train (1), in particular a rolling mill, comprising a control device (7) according to one of claims 10 to 12 for controlling the cooling process for a material (4) in the cooling bed (2).
14. Cooling bed (2) according to claim 13,
    wherein the cooling bed (2) comprises an intensive cooling line and/or a laminar cooling line.

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