CN104334754B - The control of cooling procedure - Google Patents

Abstract

The present invention relates to a method for controlling the cooling process of a material (4) using a coolant, wherein the delivery (13) of the coolant to the material (4) is controlled by at least one actuator (6), the actuator being adjustable to two or more different positions (k), wherein the actuator (6) is associated with an actuator characteristic curve family (11k) which gives the relationship between the coolant flow rate (w), the coolant pressure (p) and the position (k) of the actuator (6), and wherein the coolant flow rate (w _i ) is adjusted, for this purpose the coolant pressure ( _pi ) located upstream of at least one actuator (6) in the coolant flow direction is measured, the position ( _ki ) corresponding to the measured pressure value ( _pi ) and the rated coolant flow rate is determined by the actuator characteristic curve family (11k), and the actuator (6) is adjusted to the measured position ( _ki ).

Description

Control of the cooling process

technical field

The invention relates to a method for controlling the cooling process of a material with a coolant, a computer program product for implementing the method, a control device for controlling the cooling process of a material with a coolant, And a cooling section of a rolling mill installation, which includes the control device.

Background technique

In order to cool metal strips, in particular steel strips, it is known to apply large quantities of water as coolant to the metal strips. In the cooling section, the coolant flow rate and thus the cooling intensity must be adjusted in such a way that the desired structure of the material to be cooled is determined with high precision.

DD 213 853 A1 describes a regulating device for regulating the supply of water in a water-cooling path, which is operated for cooling a rolling stock. The regulating device consists of a flow meter and a regulating valve in the delivery duct leading to the cooling nozzle, which is connected to the regulating mechanism of the EDV plant, wherein one of several stored cooling regulating programs (EDV = electronic data processing).

DE 101 37 596 A1 describes a method for cooling workpieces, in particular rolling products made of steel. The pressure of the cooling water is adjusted by adjusting the pressure regulating valve. In this case, it is continuously monitored whether there is an impermissible deviation of the measured actual pressure value from the setpoint pressure value, and a pressure value adjustment is carried out if possible.

Such a pressure control circuit is constantly disturbed by changes in the setpoint water quantity at the valves of the cooling section. For a control loop, therefore, the behavior of the control path is constantly changing. Conversely, all flow regulation circuits are disturbed by pressure fluctuations. Therefore, this regulation of the cooling section is relatively slow. This disadvantage becomes particularly disturbing in the case of intensive cooling, ie in the case of high water demands at water pressures greater than 1 bar. This high water pressure cannot be provided only with high water tanks, so that the operation of the intensive cooling system can no longer be separated from the water pumps of the water supply.

Contents of the invention

The object of the invention is to provide better cooling of the material with a coolant.

This object is achieved by a method for controlling a cooling process of a material with a coolant, wherein the delivery of the coolant to the material is controlled by at least one actuator which can be adjusted to two or more different positions, The actuator is assigned an actuator characteristic curve which specifies the relationship between the coolant flow, the coolant pressure and the actuator position, wherein at least one coolant pump is assigned a pump characteristic curve which in the Arranged upstream of at least one actuator as viewed in the flow direction of the coolant, the pump characteristic diagram shows the relationship between the rotational speed of the pump, the differential pressure of the coolant and the coolant flow, which pressure differential occurs on the input side of the pump Between the suction pressure at the pump and the output pressure at the output side of the pump, and in which the coolant flow is adjusted, the differential pressure is determined for this purpose, and the pressure corresponding to the determined differential pressure and the nominal coolant flow is determined from the pump characteristic curve speed, setting the pump to the determined speed, determining the pressure of the coolant upstream of at least one actuator as seen in the flow direction of the coolant, the pressure values determined and measured from the actuator characteristic curve and the rated cooling The position corresponding to the agent flow, and adjust the actuator to the determined position. This task is further achieved by a computer program product for controlling the cooling process of a material with a coolant, wherein the delivery of the coolant to the material is controlled by at least one actuator, which can be adjusted to two or more different positions, wherein the actuator is assigned an actuator characteristic curve, which gives the relationship between the coolant flow, the coolant pressure and the position of the actuator, wherein at least one coolant pump is assigned a pump characteristic curve , the coolant pump is arranged upstream of at least one actuator in the flow direction of the coolant, the pump characteristic curve family gives the relationship between the pump speed, the pressure difference of the coolant, and the coolant flow rate, said A pressure difference is generated between a suction pressure at the input side of the pump and an output pressure at the output side of the pump, and wherein, when the computer program product is executed by the computing unit, the computer program product implements the following method steps: by the pump The characteristic curve family determines the speed of the pump corresponding to the pressure difference between the inlet and outlet sides of the pump and the rated coolant flow; it is determined from the actuator characteristic curve family and is at least A position corresponding to the determined coolant pressure value upstream of the actuator and the setpoint coolant flow rate; generating a signal which triggers an adjustment of the actuator to the determined position at the regulating unit assigned to the actuator; and generating A signal which triggers an adjustment to the determined rotational speed at the at least one coolant pump. Furthermore, the object is achieved by a control device for controlling a cooling process of a material with a coolant, which comprises at least one memory unit, which is designed to store an actuator characteristic curve and to store a pump characteristic a family of curves, a family of actuator characteristic curves giving the relationship between coolant flow, coolant pressure and the position of at least one actuator corresponding to the actuator characteristic curve for controlling the delivery of coolant to the material, The pump characteristic curve family gives the relationship between the pump speed, the differential pressure of the coolant that arises between the suction pressure at the input side of the pump and the output pressure at the output side of the pump, and the coolant flow rate The control device includes a processor unit designed to determine the position of the at least one actuator corresponding to the measured coolant pressure value and the setpoint coolant flow rate from the stored actuator characteristic curve, and by the determined The stored pump characteristic curves determine the rotational speed corresponding to the determined differential pressure of the coolant between the inlet side and the outlet side of the pump and the nominal coolant flow rate; and the control device includes a signal unit designed to make the user A signal for adjusting the at least one actuator to the determined position is sent to the control unit, and a signal for adjusting the at least one coolant pump to the determined rotational speed is sent to the rotational speed controller.

A common coolant is water, which is used in particular for cooling materials such as metals. The terms "flow" and "flow" are used synonymously in the description of the present invention when referring to coolant; they describe the amount of coolant that flows through a given cross-sectional area per unit of time. In this case, the cooling can take place in the form of water jet cooling, often also referred to as laminar cooling. Water jet cooling is a cooling of materials using one or more jets of water. Intensive cooling can be considered a special case of laminar cooling. Intensive cooling within the meaning of the description is characterized by a high water demand at water pressures greater than 1 bar. The water demand for intensive cooling cannot be met from the high water tank alone, so that the operation of intensive cooling - in the case of using water as coolant - is associated with the water pumps of the water supply. In this case, the valve for the intensive cooling is preferably continuously adjustable, ie the water quantity can be changed continuously, in order to be able to precisely quantify the cooling efficiency.

According to the invention, no flow control circuit is constructed, but the actuators for the coolant flow are directly actuated. Furthermore, no pressure regulation circuit is formed for the coolant quantity to be supplied to the cooling system. Here, the invention is based on the recognition that a high regulation rate for the required coolant flow, for example the cooling water flow in the cooling train, is achieved only by control, whereas the conventional regulation for this is too slow and extremely slow. Susceptible to interference, especially in conditions of intense cooling.

In this case, it preferably proceeds as follows: each actuator, for example in the form of a control valve or a valve, is assigned a first actuator characteristic curve k=f(w,p), which will input the variables coolant flow w and The coolant pressure p is mapped onto the actuator position k, and the corresponding actuator position k can be determined directly from the setpoint coolant flow w. This characteristic curve is either known in advance or determined at least once by means of a "volume measurement" of the actuator. "Volume measurement" is understood to be the experimental determination of the flow through the actuator as a function of valve position and coolant pressure. In order to calibrate the actuator characteristic curve f(w,p), a flow measurement can be carried out.

Alternatively, a second actuator characteristic curve w=g(k,p) can be stored, which maps the input variables actuator position k and coolant pressure p to the coolant flow rate w. It is also possible instead to store a third actuator characteristic diagram p=h(k,w), which maps the input variables actuator position k and coolant flow w to coolant pressure p.

Using the corresponding characteristic curves, the process computer actuates the actuators in such a way that the required coolant flow flows through each actuator. For this purpose, the actual pressure p is detected, inserted into the characteristic map of each actuator, and each setpoint coolant flow w is mapped to the corresponding setpoint actuator position k. Alternatively, the setpoint pressure is inserted into the characteristic curve instead of the actual pressure.

Test results show that the actuator designed to regulate the valve is able to move from its 0% opening to its 100% opening within 2s and from its 20% opening to its 80% opening within 1s degrees, and moreover, the pump is able to reach maximum speed from standstill in less than 1 s. Thus, the coolant flow rate can be quickly adjusted each time coolant is added to the material, and in order to provide intensive cooling, even if the coolant has to be transported first through very long conveying conduits, for example over a length in the range of 100 to 200 m For a more powerful cooling system, the coolant flow can also be adjusted more quickly.

With the invention it is possible to accelerate large quantities of coolant, such as eg approximately 150 m ³ of water, required in an intensive cooling system of a cooling train of a rolling mill plant, sufficiently quickly so that as the coolant to be cooled When the material, such as a metal strip, enters the cooling train, a stable coolant flow builds up in a very short time, for example on a timescale of typically 1 s. Thus, even in the case of thin metal strips transported through cooling trains at a speed of about 10 m/s, the length of insufficiently cooled material remains less than 10 m. In cooler trains utilizing laminar cooling, this value is in the same order of magnitude.

Cooling with the control according to the invention by the actuator therefore has the following advantages:

- Ability to provide the required coolant flow exactly at the desired point in time, eg when the strip enters the cooling train. Conversely, the coolant flow can be reduced correspondingly and rapidly at exactly the desired point in time, for example when the strip exits the cooling train.

- High regulation dynamics are also achieved during strip operation at plant limits; thus the coiling temperature can also be precisely adjusted in the case of intensive cooling, similar to that of laminar cooling. Therefore, in the case of intensive cooling, there is no reduction in the accuracy of the coiling temperature compared to laminar cooling.

- Dynamic operation not only at high coolant pressure but also at low coolant pressure is possible. If a large coolant flow is required, the nominal pressure can be increased (=high pressure operation). For applications requiring only a small coolant flow, the supply pressure p _saug of the pump can be selected as nominal pressure (=low pressure operation). In this case, the pump rotational speed can be selected such that the pump merely follows the rotation like a water meter, without changing the supply pressure of the intensive cooling itself.

- Continuous switching between low-pressure and high-pressure operation is also possible during the running cooling process. This ensures a high degree of flexibility in the cooling method, for example in steelworks production.

- The cost-intensive dynamic flow measurement by means of measuring devices upstream of each actuator, eg each valve, of the intensive cooling system can be dispensed with. Furthermore, it is also possible to omit a sufficiently long, rectilinear damping path, which is required in addition to the measuring device when measuring the flow rate and which additionally increases the cost of the cooling system.

- The invention allows efficient cooling. All coolants that are transported, in particular pumped, are used for cooling, especially for intensive cooling. In this case, the energy consumption of the pump can be further reduced by producing a higher pressure of the coolant only when actually required. For example, the need for high-pressure operation can be determined by ascertaining the position of the actuators, such as the cover position of a valve, and increasing the pressure only when the position of at least one actuator exceeds a specified opening position preset as a limit value. The rated pressure of the pump.

- The invention is an important module of a plant which allows a flexible combined cooling operation by which normal production is not disturbed or hindered, for example in a steel mill.

According to a preferred refinement of the invention, at least one actuator is adjusted continuously to the determined position. Preferably, at least one actuator is a continuously adjustable actuator. Continuous adjustment or adjustability of the at least one actuator means that the at least one actuator is adjusted steplessly to a determined position. The infinitely adjustable actuator can be, for example, a valve or a control flap.

A control method using a continuously adjustable actuator is not significantly more expensive than a cooling section with simple switching valves. In this case, the high tank decouples the water utility controls from the valve cover controls. This type of control avoids the switching valves that occur at certain temperatures, and is therefore particularly suitable for model-predictive control of time-varying cooling processes in the cooling section.

A preferred development of the invention provides that at least one coolant pump is assigned a pump characteristic curve n=q(w, Δp), which gives the coolant flow rate w and the coolant pressure difference Δp pump speed n as a function of p, the differential pressure arising between the suction pressure at the input side of the pump and the output pressure at the output side of the pump; determine the suction pressure of the coolant; and compare this differential pressure with the rated Operate the pump at a speed determined from the pump characteristic curve with an adapted coolant flow.

Alternatively, it is also possible for at least one coolant pump to be assigned a second pump characteristic curve w=r(n, Δp), which characteristic curve gives the pump speed n as a function of the coolant differential pressure Δp The coolant flow rate w of r, the pressure difference is created between the suction pressure at the input side of the pump and the output pressure at the output side of the pump. Alternatively, it is also possible for at least one coolant pump to be assigned a third pump characteristic curve Δp=s(n,w), which specifies the pump speed n as a function of the coolant flow rate w s The pressure difference Δp of the coolant that arises between the suction pressure at the input side of the pump and the output pressure at the output side of the pump.

A coolant pump, such as a water pump, which supplies coolant to a cooling installation, can be assigned a pump characteristic curve n=q(w,pp _saug ). In this case, n stands for the nominal pump speed, w stands for the coolant flow to be delivered for cooling, p stands for the pressure on the outlet side of the pump, and _psaug stands for the suction pressure on the inlet side of the pump. In this case, w must be the sum of the coolant flows of all actuators of the cooling system, including possibly also existing consumers that draw coolant from the cooling system pumps. The pump is controlled by the program computer in such a way that the pump is operated at a rotational speed n which results when the setpoint coolant flow w and the setpoint pressure increase pp _{saug are} inserted into the pump characteristic map. Advantageously, the suction pressure is measured on the inlet side of the pump for this purpose. Alternatively, an estimated value can also be used, which is determined, for example, from the height difference between the location of the pump and the coolant level in the coolant tank with which the suction side of the pump is supplied. Alternatively, it is also possible to use other desired values of the regulating device which supplies the pump with coolant on the suction side.

Advantageously, the control device not only controls the actuator, but also, for example, the pump for the high water tank, since the control device already knows in advance the coolant flow to be delivered. This can be provided in the form of so-called intelligent coolant management: in this case, in addition to actuators, such as valve covers, the control device also comprehensively operates the entire water supply and "identifies" all water in the system Consumers, ie the water consumption of the system is taken into account based on the accumulated and/or current consumption values up to now. The control device in particular also controls the intensive cooling system.

Preferably, the pump is actuated frequency-adjusted by means of a converter. The characteristic curve of the pump is either known in advance or at least once determined by measuring the volume of the pump.

Advantageously, the position of the at least one actuator and the rotational speed for operating the at least one coolant pump are determined in one step as a setpoint value set as a whole, wherein the pressure of the coolant upstream of the at least one actuator is related to the pressure at the pump The output voltages at the output side are equal.

Preferably, the process computer determines the setpoint speed of the pump and the position of the actuator, for example the position of a valve or cover, as a whole setpoint value set (=overall control) in one step. Therefore, it is not necessary to wait until actual coolant pressure does exist when operating the actuator, and vice versa. Furthermore, it is avoided that the pump could be damaged due to operation in an impermissible range. That is, when a separate pump regulation system accelerates the pump in pre-control based on a previous estimate of coolant demand, but the process computer does not open the actuator as expected, this damage can occur because there are fault and there is no setpoint group for the actuator at this time. Conversely, continuity is always ensured when there is an overall setpoint value group.

It is also possible to determine the suction pressure of the coolant on the inlet side of the pump by measurement or estimation.

According to one refinement, the characteristic curve of the actuator is adjusted, for this purpose, the pressure of the coolant is determined, in particular measured; the position of the actuator is determined; Corresponding coolant flow; compare the coolant flow determined by the actuator characteristic curve with the measured coolant flow; and change the actuator characteristic curve such that the cooling determined by the actuator characteristic curve The coolant flow is consistent with the measured coolant flow.

According to a design scheme, in order to adjust the characteristic curve family of the actuator, the characteristic curve family of the actuator given in the second form w=g(k _i , p) uses the basis function as g(k _i , p)=∑ _j c _j g _j (k _i , p) in the form c j g j (k i , p), wherein a suitable amplification factor c _j is selected for the corresponding associated basis function g _j (k _i , p). The usual disadvantage of this control, namely that the regulated coolant quantity is inaccurate compared to the case of a control system, can be compensated by adapting the characteristic curve of the actuator by means of the factor _cj .

When the basis function is a local function, for example when it is B-splines (B-Splines) that are not zero only around the expansion point, the adaptation converges particularly quickly, because the characteristic curve family is only in the currently measured The vicinity is improved, and the points of the characteristic curve which are remote from the current measurement are not changed, in particular not deteriorated.

In this approach it is also necessary to check whether the characteristic curves are still strictly monotonically increasing during or after the adaptation. This can occur, for example, when inaccurate measured values are detected, or when the initial characteristic curves are extremely inaccurate and the adaptation has to carry out extensive corrections. If the characteristic curve family is not strictly monotonically increasing after the adjustment, then the adjustment amount of the corresponding factor c _j is reduced or rolled back. Otherwise, the process computer would not be able to uniquely determine the position _ki of the actuator from a given setpoint coolant flow w _soll and pressure p by solving the equation w _soll =g( _ki , p) from _ki .

It is also possible, in an improved embodiment, to store the actuator characteristic curves in the form of a first characteristic curve k=f(w,p), which enables the direct determination of the actuator position k from the setpoint coolant flow w _i . That is to say that in this case in particular the characteristic curve set stored in the first characteristic curve form k=f(w,p) is adapted directly. For this determination, in particular the pressure p of the coolant and the coolant flow w of the coolant are measured, and the position of the actuator corresponding to the determined values, namely the pressure and the coolant flow, is determined from the actuator characteristic curve such that The actuator position determined from the actuator characteristic curve is compared with the measured actuator position and the actuator characteristic curve is changed as follows so that the actuator position determined from the actuator characteristic curve corresponds to the measured actuator position The location is the same.

According to a preferred design scheme, in order to adjust the characteristic curve family of the actuator, the characteristic curve family of the actuator given in the first form k=f(w, p) uses the basis function as f(w, p)=∑ _j a _j f _j (w, p), wherein a suitable amplification factor a _j is selected for the corresponding associated basis function 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 nominal water volume w _soll according to _ki = f(w _soll , p), without having to invert the characteristic curves beforehand. It is particularly advantageous in this procedure that when the coefficients a _j are adjusted by the adaptation, it is not necessary to check whether the characteristic curve is still strictly monotonically increasing. Another advantage of this approach is that it eliminates the computational cost of unwrapping nonlinear functions in terms of variables.

According to an advantageous development of the invention, the pump characteristic curves are adjusted, for this purpose, the differential pressure and the flow rate of the coolant are determined, the pump speed corresponding to the determined values is determined from the pump characteristic curves, the pump characteristic curves The pump rotational speed determined from the pump characteristic curve is compared with the measured rotational speed, and the pump characteristic curve family is changed in such a way that the pump rotational speed determined from the pump characteristic curve coincides with the measured pump rotational speed.

Advantageously, in order to adjust the pump characteristic curves, the pump characteristic curves given in the second form n=q(w,pp _saug ) with the aid of basis functions q(w,pp _saug )=∑ _j c _j g _j (w, pp _saug ), wherein a suitable amplification factor b _j is selected for the corresponding associated basis function q _j (w, pp _saug ).

The usual disadvantage of this control, namely that the adjusted coolant quantity is inaccurate compared with the situation of the control system, can be compensated by an adaptation of the pump characteristic curve by means of the factor _bj .

It is also possible to store the pump characteristic curves in the second form w=r(n,pp _saug ). However, when the rated speed of the pump is to be determined, the pump characteristic curve must be unwrapped in terms of n. This is particularly disadvantageous when the pump characteristic curve is to be adjusted; if it is desired to adjust the pump characteristic curve in the form w=r(n, pp _saug ), it cannot be guaranteed to be unwrapped uniquely as a function of the pump speed. Therefore, error control cannot be ruled out in this case. Correspondingly, the same is true when the pump characteristic curve family is expressed in the third form Δp=pp _saug =s(n,w). When the nominal rotational speed of the pump is to be determined, this pump characteristic curve must also be unwound in this case as a function of n.

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

Another preferred development of the invention is a cooling section of a rolling mill installation, which comprises the aforementioned control device for controlling the cooling of the material in the cooling section.

According to a preferred design solution, the cooling section includes an intensive cooling section and/or a laminar cooling section. Thus, the invention can be used not only in intensive cooling sections, but also in laminar cooling sections. The invention is not limited to intensive cooling. As the actuator is continuously adjustable in the region of the normal laminar cooling section, this region can also be controlled in this way. In particular, the invention can also be implemented when the variable-speed pump supplies the coolant directly from the coolant supply network, for example water directly from the water supply network, ie without a tall water tank arranged therein and serving as a buffer zone.

With intensive cooling, sections of the cooling section with particularly high cooling efficiency can achieve high cooling rates. The advantage of intensive cooling, also known as the "Power Cooling" method, is that it is thereby possible to cool faster, i.e. at a higher cooling rate, harder and high hardness materials over a wide range of thicknesses. of steel. This enables a highly accurate and efficient production of additional steel grades, in particular steel grades with a higher hardness than hitherto.

It can be particularly expedient for an intensive cooling section to be carried out in the front region of the cooling section in order to limit grain growth in the raw material, accelerate phase transformation of the material and thus increase the hardness of the material overall. In certain cases, however, it can also make sense for this intensive cooling to take place after the blooming stand, or it can be installed at another location in the cooling section. It is also possible to arrange intensively chilled beams between the stands of the finishing train.

For example, a strip cooling system for a hot rolling mill can include semi-finished strip cooling as well as finished strip cooling, and the system consists of an intensive cooling section and a laminar cooling section. Here, the semi-finished strip cooling system can be installed in the area of the intermediate roller table behind the blooming stand. It equalizes the temperature of the semi-finished strip over its entire length and width before entering the finishing train. An intensive cooling section can be arranged at the output end of the finishing train. A laminar cooling section can be positioned immediately after the intensive cooling system. Typically, these two devices operate together.

For applications in the cooling section, it is of particular interest that the adjustment range of the cooling facility is large enough in the direction of small water volumes so that when producing materials that only allow the use of low cooling rates, intensive cooling can be performed as Normal laminar cooling is used as well. Since during production materials with high cooling efficiency are mixed with standard products requiring low cooling efficiency, the rapid switching of cooling efficiency achieved by the present invention is extremely advantageous. Thus, the invention bypasses the extremely disadvantageous solution that requires pushing out large pipes every time the cooling water volume is switched, for example from high pressure operation to low pressure operation by shutting off the booster pump and activating the supply from the tank for low pressure operation conversion. Such a solution can only be switched, for example, during a roll change or other longer standstills, but not during ongoing production.

Another advantage of the present invention is the dynamic transfer of large water volumes when the strip enters or when the strip leaves the intensive cooling system again. Strips in intensive cooling may require cooling water volumes in the range of 8000m ³ /h. In general, the intensive cooling cannot already be activated before the strip enters the cooling section, because in the case of thin strips, the forces acting on the strip by the water can cause the strip to lift. On the other hand, when the strip is thicker, generally a hotter strip is required over the first few meters of the strip so that the take-up device can grab the strip and bend it around the mandrel. This means that, in particular, large water volumes must be changed highly dynamically when the strip is entering and when the strip is leaving. The present invention provides this dynamic.

Furthermore, the invention makes it possible to precisely dose the high water volumes used in intensive cooling. The exact amount of water used to apply intensive cooling is decisive for the exact coiling temperature that can be achieved. This is particularly important so that the advantages of high cooling rates, increased hardness, cannot be translated into disadvantages of poor reproducibility of the material properties. By utilizing the accuracy of coolant flow that the present invention enables, when running intensive cooling at low cooling efficiencies to manufacture standard products, it is possible to avoid that coil temperature accuracy is degraded compared to standard laminar cooling. However, the present invention also avoids a noticeable deterioration in coil temperature accuracy when operating at high cooling efficiencies.

Preferably, the present invention represents the application of a control method for coolant actuators according to characteristic diagrams in the cooling section of a metal processing train, in particular in a hot strip shop, and preferably additionally according to Application of the characteristic curve family to the control method of the coolant pump. However, the invention can also be used in particular in heavy plate trains, in which thick plates have to be produced and cooled.

Description of drawings

The above-mentioned properties, features and advantages of the present invention as well as the ways and means for achieving them will become more comprehensible in conjunction with the following description of the embodiments in detail with the aid of the accompanying drawings. which shows:

Fig. 1 is a row of metal processing machines;

Fig. 2 is the characteristic curve family of the first actuator;

Fig. 3 is the characteristic curve family of the second actuator;

Fig. 4 is the first pump characteristic curve family;

Figure 5 is a second family of pump characteristic curves; and

Figure 6 is a suitable diagram for coolant flow control.

detailed description

FIG. 1 shows a metal processing train 1 , which is designed here as a cooling train 2 , also referred to as a cooling section. A cooling train 2 is downstream of the finishing train, the last rolling stand of which is indicated at 3 . The material 4 of the metal 4 to be processed, which is formed in the form of a strip, first passes through the finishing train and then through the cooling section 2 and is then coiled in the cooling zone for transport or for intermediate storage until further processing. On the coiler 5 downstream of section 2.

The metal processing train 1 can be arranged, for example, in a hot-strip mill of a steel plant.

The cooling section 2 comprises an actuator 6 with which a defined coolant flow can be delivered to the material 4 and a coolant delivery system 13 by which the coolant can be delivered from a coolant store, for example from In the water supply network or high water tank, delivered to the actuator 6; and includes a coolant pump 20 connected to the coolant delivery system 13, with which the pump can be changed for the coolant pressure on the input side 20e of the pump 20 The coolant pressure on the output side 20a of 20. In this case, the actuator 6 comprises a cover and a valve, with which water, which can be used as coolant, is applied, for example sprayed, via the cooling beams 14 onto the strip metal 4 in order to cool the metal.

Although only a few actuators 6 are shown in FIG. 1 , the cooling section 2 can contain a large number of such actuators 6 . In this case, all actuators can be supplied with coolant by the same pump. It is also possible that there are two or more pumps which each supply one or more actuators with coolant.

The cooling section 2 also includes a control device 7 which is shown schematically in FIG. 1 . The control device 7 comprises a computing unit 8, a storage unit 12, an input facility 9 for inputting data into the computing unit 8, and a display facility 10 for displaying the data. The computing unit 8 controls an actuator 6 , for example a valve, a nozzle or a cap, via a control line 15 according to the actuator characteristic map 11w. Furthermore, the computing unit 8 controls the coolant pump 20 via the control line 15 as a function of the pump characteristic map 11n.

In order to be able to reduce the temperature of the material 4 in a targeted manner, the actuators 6 are individually actuated and thus the throughflow rates of the cooling beams 14 are adjusted individually. The high water tank feeds the chilled beams 14 with coolant, in particular water, via a coolant delivery system 13 . At particularly high cooling rates, the pump 20 can be switched on. In this way, the cooling can be adjusted depending on the material produced in question, for example the type of steel.

It is possible that the control device 7 can be changed in the manual operating mode by an operator at least partially via the input device 9 so that, for example, the actuators 6 can be actuated in groups or individually. The manual drivability does not have to be designed to be permanent, but it is also conceivable to be able to switch between automatic and manual operating modes.

In addition, computing unit 8 obtains further information about the state of cooling section 2 or metal 4 . In addition to the measured values relating to the coolant pressure at the different locations of the coolant delivery system 13 , preliminary data of the metal 4 describing the metal 4 or its state when entering the cooling section 2 are also supplied to the computing unit 8 , Such as the chemical composition of the metal, the velocity v and the metal temperature T.

One or more actuator characteristic curves 11w and one or more pump characteristic curves 11n are stored in the storage unit 12 . Depending on the type of actuator or pump, one of the stored characteristic curves is assigned to the corresponding component. Preferably, two or more actuators or pumps of the same type are assigned the same characteristic curve; this results in faster convergence in the cooling system and faster control of the cooling. However, it is also possible to assign individual characteristic curves 11w or 11n to each actuator 6 and each pump 20 .

FIG. 2 shows a diagram of a first actuator characteristic diagram 11k, which describes the dependence of the coolant pressure p and the coolant flow w through the actuator 6 on one another using the position _ki of the actuator 6 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 rate w increases along the w-axis (=x-axis). The parameter curve _ki defines the correlation between the coolant pressure p and the coolant flow w for different positions _ki of the actuator 6; when k=10%, the opening degree of the actuator is 10%, and at When k=90%, the opening degree of the actuator is 90%. The actuator characteristic map 11k can be stored in a memory unit of the control device.

The actuator characteristic curve 11k in the form of the first characteristic curve k=f(w,p) has the advantage that the actuator position k _i can be determined directly from the setpoint coolant flow w _{i, soll} : the process computer of the control device for each Each actuator determines the actual pressure p _i , inserts it into the actuator characteristic curve 11k of the associated corresponding actuator, and based on the actuator characteristic curve 11k for each nominal coolant flow w _{i, soll} determines the execution The corresponding nominal actuator position _ki of the mechanism. The process computer then controls the actuators accordingly. For this purpose, the signal unit of the control device sends a signal for adjusting at least one actuator to the determined position _ki to an adjusting unit for adjusting the actuator.

FIG. 3 shows a further second actuator characteristic curve 11w in a drawing, which describes the dependence of the position k of the actuator 6 and the coolant pressure p on each other using the coolant flow rate 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 _ki of the actuator 6 increases along the k-axis (=x-axis); when k=0, the opening degree of the actuator is 0 percent, and when k=100, the opening degree of the actuator is 100 percent of 100. The parameter curve w defines the mutual dependence of the coolant pressure p and the position _ki of the actuator for different coolant flows w.

The second actuator characteristic curve 11w is used to determine the position k _i of the actuator 6 in which the desired coolant flow rate, ie the setpoint coolant flow rate w i , is obtained at a preset coolant pressure p _{i , soll} . According to the cooling section 2 shown in FIG. 1 , this proceeds as follows: First, the pressure p _i of the coolant seen in the flow direction of the coolant between the coolant pump 20 and the actuator 6 is determined. This determination can be performed by pressure measurement or estimation. Subsequently, the position ki of the actuator 6 corresponding to the determined pressure value p _i and the setpoint coolant flow w _{i , soll} is determined from the actuator characteristic diagram 11 w assigned to the actuator 6 . Finally, the relevant actuator 6 is adjusted to the determined position k _i .

If a difference greater than a permissible tolerance value occurs between the actual coolant flow, determined for example by flow measurement of the coolant flow, and the coolant flow w _{i, soll} expected from the actuator characteristic map 11w, preferably , an adaptation of the actuator characteristic curve 11w to the actual relationship is carried out. To this end, the actuator characteristic curve family 11w given in the form of w=g(k,p), with the basis function g _j (k,p) with g(k,p)=∑ _j c _j f _j (k, p) where w represents coolant flow, p represents coolant pressure and k represents actuator position. A suitable amplification factor c _j is selected for the associated basis function g _j (k, p), for which purpose the pressure p of the coolant is determined, in particular the pressure p of the coolant is determined, the position k of the actuator 6 is determined from which the value is determined by means of the basis function (= volumetric flow rate) d _j = g _j (k, p), and the amount of change Δc _j of the amplification factor c _j is selected by using the value d _j as follows so that the measured coolant flow rate w approaches the rated coolant flow rate w _soll , and minimize the variation △c _j of the amplification factor c _j .

FIG. 4 graphically shows a pump characteristic diagram 12n, which describes the difference Δp of the coolant pressure upstream and downstream of the coolant pump 20 and the coolant flow w relative to each other using the rotational speed n of the coolant pump 20 as a parameter. The correlation between: n=q(w, △p). The pressure difference Δp increases along the Δp axis (=y axis), starting at Δp=0. The coolant flow rate w increases along the w-axis (=x-axis). The parameter curve n defines the correlation between the coolant differential pressure Δp and the coolant flow rate w for different rotational speeds n of the coolant pump 20 .

The pump characteristic diagram 12n is used to determine the rotational speed n _i at which the desired coolant flow, ie the setpoint coolant flow w _i,soll , is obtained at a predetermined coolant pressure difference Δp. According to the cooling section 2 shown in FIG. 1 , this proceeds as follows: firstly the suction pressure p _saug of the coolant, ie the coolant pressure at the inlet side 20 e of the pump 20 , is determined and the nominal differential pressure Δp _soll is calculated therefrom . The pump rotational speed n _i is then determined from the pump characteristic diagram 12n for the calculated setpoint differential pressure Δp _soll and setpoint coolant flow w _{i, soll} . Finally, the rotational speed of the pump 20 is adjusted to the determined value _ni .

If a difference greater than a permissible tolerance value occurs between the actual coolant flow, determined for example by flow measurement of the coolant flow, and the expected coolant flow w _{i, soll} according to the pump characteristic curve 12n, preferably, the execution Adaptation of the pump characteristic curve 12n to the actual relationship.

For this purpose, the pump characteristic curve 12n given in the form n=q(w, pp _saug ) is represented by means of basis functions in the form q(w, pp _saug )=∑ _j b _j q _j (w, pp _saug ) where n represents the pump speed, p represents the output pressure at the output side 20a of the pump 20, p _saug represents the suction pressure at the input side 20e of the pump 20, and w represents the coolant flow rate. A suitable amplification factor b _j is selected for the corresponding associated basis function q _j (w, pp _saug ), for which purpose the coolant delivery pressure p at the delivery side 20 a of the pump is determined, in particular measured. From this, the coolant pressure difference Δp is determined using the known coolant suction pressure p _saug , ie the coolant pressure at the inlet side 20 e of the pump 20 . Furthermore, the coolant flow w _i is determined, preferably measured. From this, the value (=rotational speed) e _j =q _j (w, pp _saug ) is determined with the aid of the basis function, and the variation Δb _j of the amplification factor b _j is selected by using the value e _j as follows such that the pump characteristic curve 12n according to The expected pump speed is close to the actual pump speed and minimizes the variation Δb _j of the amplification factor b _j .

FIG. 5 shows a further second pump characteristic diagram 12w in the figure, which describes the difference Δp of the coolant pressure upstream and downstream of the coolant pump 20 and the pump speed n relative to each other using the coolant flow rate w as a parameter. The correlation among them: w=r(n, △p). 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 curve w defines the correlation between the coolant differential pressure Δp and the rotational speed n for different volume flow rates w of the coolant.

FIG. 6 schematically shows the control of the coolant flow to the material 4 to be cooled. In the coolant delivery system 13 in the form of a pipe, a pump 20 is arranged in the flow direction of the coolant and a valve 6 is arranged downstream thereof. Upstream of the pump 20 , ie at the inlet side 20 e of the pump 20 , as seen in the flow direction of the coolant, the coolant has a pressure referred to as the suction pressure p _saug . Downstream of the pump 20 , ie at the output side 20 a of the pump 20 , seen in the flow direction of the coolant, the coolant has a pressure referred to simply as p, which is induced by the pressure change produced by the pump 20 by the suction Obtained from pressing p _saug . The operation of the pump 20 , in particular its rotational speed n, is controlled by means of the pump characteristic map 12n. The flow rate of the valve 6 arranged downstream of the pump 20 , viewed in the flow direction of the coolant, is controlled by means of the actuator characteristic map 11 k . Thus, the coolant flow w _i of coolant onto the material 4 can be accurately controlled by the pump 20 and the valve 6 .

If there is neither a coolant source nor a coolant _outlet between the pump 20 and the valve 6, as shown in FIG. Agent flow, that is, w _{i, valve} = w _{i, pump} . Preferably, therefore, if it is not possible to determine, in particular if it is not possible to measure the coolant flow rate w _i , the actuator characteristic diagram 11 k and the pump characteristic diagram 12 n can be adjusted relative to each other as follows such that they provide non-contradictory results.

Furthermore, preferably if it cannot be determined, in particular if the coolant flow w _i cannot be measured, it can be adapted as a function of the temperature of the material to be cooled, eg a metal part. Errors in the coolant flow w _i can thus be compensated or eliminated. When the temperature pattern is sufficiently known, it is possible to deduce from the specified coolant flow w _i the cooling down with a determined temperature difference.

Although the invention has been illustrated and illustrated in detail by preferred exemplary embodiments, the invention is not restricted to the disclosed examples and a person skilled in the art can derive other variants therefrom without departing from the scope of protection of the invention.

Claims (20)

1. A method for controlling the cooling process of a material (4) with a coolant, wherein the delivery (13) of said coolant to said material (4) is controlled by at least one actuator (6) which can be adjusted to two or more different positions (k), wherein said The actuator (6) is assigned a monotonic actuator characteristic curve (11k, 11w), which specifies the coolant flow rate (w), the coolant pressure (p) and the actuator The relationship between the positions (k) of the means (6), wherein at least one coolant pump (20) arranged upstream of at least one of the actuators (6), as seen in the flow direction of the coolant, is associated with Monotonic pump characteristic curve family (12n, 12w), described pump characteristic curve family gives at the rotational speed (n) of the pump (20), the differential pressure of the coolant (Δp) and the coolant flow rate ( w) the relationship between the pressure difference between the suction pressure (p _saug ) at the input side (20e) of the pump (20) and the output pressure at the output side (20a) of the pump (20) obtained between; and where the coolant flow rate (w _i ) is adjusted, for which the differential pressure (Δp) is determined, and the differential pressure (Δp) of the pump is determined from the pump characteristic curve (11n) The rotational speed (n _i ) corresponding to the nominal coolant flow rate (w _{i, soll} ), the pump (20) is adjusted to the determined rotational speed ( _ni ), measured in the flow direction of the coolant as seen in The pressure (p _i ) of the coolant upstream of at least one of the actuators ( 6 ), the measured pressure (pi ) of the actuator and the measured pressure ( _pi ) of the actuator are determined from the actuator characteristic curves ( 11w The position (ki ) corresponding to the rated coolant flow rate (w _{i , soll} ) is determined, and the actuator (6) is adjusted to the determined position ( _ki ). 2. The method of claim 1, In this case, at least one actuator ( 6 ), which is steplessly adjustable to two or more different said positions (k), is continuously adjusted to said determined position ( _ki ). 3. The method according to claim 1 or 2, wherein the position of at least one actuator (6) and the rotational speed for operating at least one coolant pump (20) are determined in one step as an overall setpoint value set, Therein, the pressure of the coolant upstream of at least one of the actuators (6) is equal to the output pressure at the output side (20a) of the pump (20). 4. The method according to claim 1 or 2, Therein, the suction pressure (p _saug ) at the input side ( 20 e ) of the pump ( 20 ) is measured or estimated. 5. The method of claim 3, Therein, the suction pressure (p _saug ) at the input side ( 20 e ) of the pump ( 20 ) is measured or estimated. 6. The method according to claim 1 or 2, Wherein, the actuator characteristic curve family (11k) is adjusted, the pressure of the coolant (p _i ) is determined for this purpose, the coolant flow rate (w _i ) of the coolant is determined, and the actuator characteristic curve family (11k) Determining the position of said actuator (6) corresponding to the measured value (w _i , p _i ), the position of said actuator (6) measured from said actuator characteristic curve (11k) The position is compared with the measured position of the actuator (6), and the actuator characteristic curve (11k) is changed such that the actuator (6) determined from the actuator characteristic curve (11k) ) is consistent with the measured position of the actuator (6). 7. The method of claim 5, Wherein, the actuator characteristic curve family (11k) is adjusted, for which the pressure of the coolant is determined, and the coolant flow rate (w _i ) of the coolant is determined, determined from the actuator characteristic curve family (11k) The position of the actuator (6) corresponding to the measured values (w _i , p _i ), the position of the actuator (6) determined from the actuator characteristic curve (11k) is related to the The measured position of the actuator (6) is compared and the actuator characteristic curve (11k) is changed such that the position of the actuator (6) determined by the actuator characteristic curve (11k) is equal to The measured positions of the actuators (6) coincide. 8. The method of claim 6, Wherein, the actuator characteristic curve family (11k) is given in the form of k=f(w,p), where w represents the coolant flow rate, p represents the pressure of the coolant and k represents the position of the actuator, in order to adjust the actuator characteristic curve (11k), the actuator characteristic curve with the aid of the basis function f _j (w, p) is expressed in the form of f(w, p)=∑ _j a _j f _j (w, p), wherein the selection of the basis function f _j (w, p) suitable for the corresponding assignment Amplification factor a _j . 9. The method of claim 7, Wherein, the actuator characteristic curve family (11k) is given in the form of k=f(w, p), where w represents the coolant flow rate, p represents the pressure of the coolant and k represents the position of the actuator, in order to adjust the actuator characteristic curve (11k), the actuator characteristic curve with the aid of the basis function f _j (w, p) is expressed in the form of f(w, p)=∑ _j a _j f _j (w, p), wherein the selection of the basis function f _j (w, p) suitable for the corresponding assignment Amplification factor a _j . 10. The method according to claim 1 or 2, Wherein, the pump characteristic curve family (12n) is adjusted, and the pressure difference (△p) and the flow rate (w _i ) of the coolant are determined for this purpose, which is determined by the pump characteristic curve family (12n) and determined The pump speed (n) corresponding to the value (Δp, w _i ), the pump speed determined by the pump characteristic curve (12n) is compared with the measured pump speed, and the pump characteristic curve is changed family (12n), such that the pump speed determined from the pump characteristic curve family (12n) coincides with the measured pump speed. 11. The method of claim 9, Wherein, the pump characteristic curve family (12n) is adjusted, and the pressure difference (△p) and the flow rate (w _i ) of the coolant are determined for this purpose, which is determined by the pump characteristic curve family (12n) and determined The pump speed (n) corresponding to the value (Δp, w _i ), the pump speed determined by the pump characteristic curve (12n) is compared with the measured pump speed, and the pump characteristic curve is changed family (12n), such that the pump speed determined from the pump characteristic curve family (12n) coincides with the measured pump speed. 12. The method of claim 10, Wherein, the pump characteristic curve family (12n) is given in the form of n=q(w, pp _saug ), Wherein, n represents the pump speed, p represents the output pressure on the output side (20a) of the pump (20), and p _saug represents the output pressure on the input side (20e) of the pump (20). The suction pressure of , and w represents the coolant flow rate, in order to adjust the pump characteristic curve family (12n), the pump characteristic curve family is expressed as q(pp _saug , w)=∑ _j b by basis functions _j q _j (w, pp _saug ), wherein the amplification factor b _j is chosen to be suitable for the corresponding associated basis function q _j (w, pp _saug ). 13. The method of claim 11, Wherein, the pump characteristic curve family (12n) is given in the form of n=q(w, pp _saug ), Wherein, n represents the pump speed, p represents the output pressure on the output side (20a) of the pump (20), and p _saug represents the output pressure on the input side (20e) of the pump (20). The suction pressure of , and w represents the coolant flow rate, in order to adjust the pump characteristic curve family (12n), the pump characteristic curve family is expressed as q(pp _saug , w)=∑ _j b by basis functions _j q _j (w, pp _saug ), wherein the amplification factor b _j is chosen to be suitable for the corresponding associated basis function q _j (w, pp _saug ). 14. A control device (7) for controlling the cooling process of a material (4) with a coolant, comprising - at least one memory unit (12) designed to store actuator characteristic curves (11k, 11w) which give the coolant flow rate (w _i ), the coolant between the pressure (p) of the coolant and the position ( _ki ) of at least one actuator (6) assigned to the actuator characteristic curve for controlling the delivery of the coolant to the material (4) relationship; and the storage unit is designed to store the pump characteristic curve family (12n, 12w), the pump characteristic curve family gives the rotational speed (n) of the pump (20), the differential pressure of the coolant (Δp ) and the coolant flow rate (w), the pressure difference is the suction pressure (p _saug ) at the input side (20e) of the coolant pump (20) and the coolant pump (20) Obtained between the output pressure at the output side (20a) of the - a processor unit (8), which is designed to determine from the stored actuator characteristic curves (11k, 11w) and the determined value of at least one actuator (6) The pressure of the coolant (p _i ) and the position ( _ki ) corresponding to the nominal coolant flow rate (w _i ) are determined from the stored characteristic curves of the pump (12n, 12w) and the determined, the The coolant pressure difference (Δp) between the input side (20e) and the output side (20a) of the pump (20) corresponds to the rated coolant flow rate (w _{i, soll} ). the rotational speed (n _i ) of the pump (20), - a signal unit (22), which is designed to transmit a signal for adjusting at least one of the actuators (6) to the determined position ( _ki ) to the adjustment unit, and to transmit a signal for A signal for regulating at least one of the coolant pumps (20) to the determined rotational speed (n _i ) is sent to the rotational speed controller. 15. The control device (7) according to claim 14, Wherein, the control device (7) includes at least one actuator (6). 16. The control device (7) according to claim 15, wherein the actuator is preferably designed as a valve or a regulating valve. 17. The control device (7) according to claim 15, In this case, at least one actuator (6) can be adjusted continuously. 18. A cooling section (2) of a metalworking train (1), comprising a control device (7) according to any one of claims 14 to 17, for controlling the cooling section (2) in the cooling section (2) The cooling process of material (4). 19. The cooling section of claim 18, wherein the metal working train is a rolling mill installation. 20. The cooling section (2) according to claim 19, wherein the cooling section (2) comprises an intensive cooling section and/or a laminar cooling section.