US20260008087A1

US20260008087A1 - Method, computer program and cooling system for monitoring a component of the cooling system in a rolling mill

Info

Publication number: US20260008087A1
Application number: US18/881,690
Authority: US
Inventors: Christoph Hassel; Ulrich Cramer; Jens Kiessling-Romanus; August Sprock; Frank Theobald
Original assignee: SMS Group GmbH
Current assignee: SMS Group GmbH
Priority date: 2022-08-15
Filing date: 2023-07-21
Publication date: 2026-01-08
Also published as: EP4572901A1; JP2025529779A; WO2024037827A1; DE102022208447A1

Abstract

A method allows monitoring a component of a cooling system in a rolling mill, the cooling system including the component being used to apply a coolant on a rolled stock to be cooled. To apply a coolant on the rolling stock with a desired target pressure or target volume flow, not only when the component is in the new state but also with the component in the used state, the cooling system provides for the acquisition of actual characteristic data for the component during and/or after the period of use of the component. These actual characteristic data are compared with predetermined target characteristic data, in order to determine a possible characteristic data deviation A, which represents a malfunction of the component with respect to its new state. The method then provides various measures for minimizing the characteristic data deviation, if this exceeds a predetermined threshold value.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a national stage application, filed under 35 U.S.C. § 371, of International Patent Application PCT/EP2023/070324, filed on Jul. 21, 2023, which claims the benefit of German Patent Application DE 10 2022 208 447.0, filed on Aug. 15, 2022.

TECHNICAL FIELD

The disclosure relates to a method and a computer program for monitoring a component of a cooling system in a rolling mill, wherein the cooling system comprising the component is used to apply a coolant on a rolled stock to be cooled. The disclosure also relates to the corresponding cooling system.

BACKGROUND

Known cooling systems in rolling mills substantially consist of a cooling section with a plurality of spray nozzles, which are supplied with a coolant via a system of pumps and valves. The coolant is preferably fed to the spray nozzles at the required pressure; for this purpose, the coolant is stored in an elevated tank and/or the required pressure is generated by one or more pumps. In general, the known cooling system typically comprises a control device or a control loop with an actuator for setting or regulating the actual pressure or the actual volume flow with which the coolant is applied on the rolled stock to be cooled. Thereby, various components of the cooling system, such as the pumps, valves or the spray nozzles themselves, are used as actuators. The aforementioned control devices or control loops offer the advantage of dynamic and precise application of the coolant at a desired target pressure or target volume flow. The use of speed-controlled pumps makes it possible to keep pressure losses-and thus energy losses-caused by the aforementioned actuators in the cooling system as low as possible.
A large number of publications deal with the control and regulation systems described above and their optimization. One such publication is, for example, the European patent application EP 3 495 056 A1. This document describes an operating method for a cooling section for cooling hot rolled stock made of metal, wherein the cooling section has a pump that draws coolant from a coolant reservoir and feeds the coolant via a line system to a number of coolant outlets that are controlled via valves arranged upstream of the coolant outlets. The control unit of the cooling section carries out the following steps cyclically: Taking into account the coolant flows that are to be discharged via the coolant outlets at any given point in time, control states for the valves are determined in conjunction with the working pressure of the coolant on the inlet side of the valves. A total coolant flow is determined by adding up the coolant flows. Taking into account the total coolant flow and the working pressure of the coolant, a pump pressure is determined that should prevail on the inlet side of the pump, such that the working pressure is reached on the inlet side of the valves. Taking into account the total coolant flow, the pump pressure and a suction pressure prevailing on the inlet side of the pump, a control state for the pump is determined. The valves and the pump are controlled according to the control states determined. In order to be able to provide the required quantity of coolant with high accuracy at all times, even without a storage option for coolant between the pump and the coolant outlets, the control device cyclically takes into account a change in the total coolant flow in addition to the total coolant flow and the working pressure of the coolant when determining the pump pressure for the given point in time.
Irrespective of this prior art, it is common practice to record a calibration characteristic of the actuators when commissioning a cooling system, in order to be able to quickly set their operating points later. The calibration characteristic curve of the actuators, also known as the baseline characteristic curve, comprises the target characteristic data of the actuator that describes the calibrated behavior of the actuator in a wear-free and fault-free state during the operation of the cooling system, which is preferably also wear-free and fault-free. In practice, contamination, deposits, corrosion and wear occur in the course of time on the actuator and in the system in which the actuator is operated. It can also happen that the outlet openings of the spray nozzles become blocked, such that the maximum cooling water quantities can no longer be set. A uniform cooling of the rolled stock across the width of the strip is then no longer possible, which may result in a loss of quality during production.
All of these negative changes to the actuator or in the environment of the actuator are traditionally acquired in a so-called “system characteristic curve,” which can change over the course of the operating time of the cooling system. The term “change in the system characteristic curve” is used below as a synonym for the aforementioned negative changes.
For an exact/current setting of a component/an actuator in a cooling system, it is therefore necessary to know its current operating characteristic curve, which results from a superimposition of the baseline characteristic curve with the system characteristic curve; see the lecture notes “Measurement, Control and Regulation Engineering” from the Institute of Process Engineering at the University of Linz, Wälser Str. 42, 4060 Leonding/A.
A manual state monitoring of the cooling system can usually only be performed during a system shutdown and is usually highly labor-intensive, in particular with the typical size of a cooling section in a rolling mill with a large number of actuators to be monitored with regard to their state.

SUMMARY

The disclosure is based on the object of further developing a known method and computer program for monitoring a component of a cooling system in a rolling mill along with a corresponding known cooling system comprising the component for applying a coolant on a rolled stock to be cooled, in such a way that the coolant is always applied on the rolled stock to be cooled at a desired target pressure or a desired target volume flow, even if the system characteristic curve changes in the course of time.
This object is achieved by the method as disclosed and claimed.
The purpose of the disclosure is to establish a preferably continuous state monitoring of the components/actuators of cooling systems in a rolling mill. The method provides that during and/or after an operating period of the component/actuator of the cooling system, actual characteristic data for the component are acquired and subsequently compared with previously determined/specified target characteristic data for the component. Thereby, the actual characteristic data represent/include the actual state of the component in its environment, including all negative changes that possibly exist. On the other hand, the target characteristic data represent the component and its environment in a fault-free, in particular wear-free state. The comparison makes possible the determination of a possible characteristic data adjustment, which represents/indicates a malfunction of the component. The method provides that measures for minimization or adjustment are taken if the deviation in characteristic data exceeds a predetermined threshold value. With the acquired actual characteristic data for the component and its comparison with the target characteristic data for the component, it is possible to draw conclusions about the wear states of the component. As a result, reliable data can also be determined for maintenance and servicing. In this manner, the production time of the rolling mill can be increased by avoiding unplanned system downtimes during production operations and postponing maintenance work to the planned maintenance downtimes.
In accordance with a first exemplary embodiment, the measure to be taken for minimizing the characteristic data deviation can consist of outputting a warning or a notice to an operator of the cooling system or to a signaling system for the purpose of checking and, if necessary, repairing or replacing the particular component.
An additional or alternative measure for minimizing the characteristic data deviation can be provided: Introducing of the characteristic data deviation or a correction value calculated from it as a disturbance variable in the sense of a disturbance variable introduction to the open-loop or closed-loop controller for determining a corrected control variable and for outputting the corrected control variable at the output of the open-loop or closed-loop controller to the component. As a result, an even better consideration of a system characteristic curve that changes in the course of time can be achieved when controlling the component.
In accordance with a further measure, the characteristic data deviation or the correction value calculated from it can alternatively or additionally be applied as a disturbance variable to a target value specification device, which is typically connected upstream of the open-loop or closed-loop controller. The introduced characteristic data deviation or the introduced correction value calculated from it is then used in the target value specification device to adjust the target value for the open-loop or closed-loop controller accordingly.
In accordance with a further exemplary embodiment, at least some of the steps are repeated several times, preferably continuously, during the operation of the cooling system or during breaks in operation of the cooling system. With a high frequency of repetitions, even small changes in the system characteristic curve can be acquired and taken into account when controlling the component/actuator.
The component comprises, for example, a pump, a valve or a spray nozzle within the cooling system.
The actual characteristic data comprise at least individual points of an operating characteristic curve of the component, which describes the behavior of the used component during the operation of the cooling system at the point in time of its acquisition. The term “used component” means that the component exhibits altered behavior due to signs of use, for example due to deposits or wear, for example, compared to its like-new or fault-free state.
The target characteristic data of at least individual points of a calibrated characteristic curve of the component in a fault-free state are measured during the operation of the cooling system, typically during startup.
The object mentioned above is further achieved by a computer program product and by a cooling system. The advantages of this solution correspond to the advantages mentioned above in relation to the aforementioned method.
The computer program product comprises a physical distributable software product that comprises software code sections as a program.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the part of the cooling system on the coolant side;

FIG. 2 shows the control-related part of the cooling system in accordance with a first exemplary embodiment;

FIG. 3 shows a comparison of a calibrated characteristic curve and an operating characteristic curve of a component of the cooling system;

FIG. 4 shows the control-related part of the cooling system in accordance with a second embodiment; and

FIG. 5 shows the control-related part of the cooling system in accordance with a third exemplary embodiment.

DETAILED DESCRIPTION

The invention is described in detail below with reference to the specified figures in the form of exemplary embodiments. In all figures, the same technical elements are designated with the same reference signs.
FIG. 1 shows the part of the cooling system 100 on the coolant side. The cooling system is used for cooling a rolled stock 20 in a rolling mill. For this purpose, the cooling system has a supply device 10 in order to provide the coolant, preferably at a predetermined pressure, for cooling the rolled stock. The coolant is fed via at least one line 12 from the supply device 10 to an application device 4, for example a cooling bar with spray nozzles, for applying the coolant on the rolled stock 20. A component 3, for example in the form of a pump or a valve, is typically installed in the line 12 for controlling or regulating the pressure of the volume flow with which the coolant is to be fed to the application device 4. A pressure or volume flow meter 5 is also installed in the line for determining the current actual pressure or actual volume flow of the coolant in the line.
The horizontal arrow pointing to the left, to be seen in FIG. 1 , indicates the direction of flow of the coolant from the supply device 10 to the application device 4.
FIG. 2 shows the control-related part of the cooling system 100. It can be seen that the component 3, shown here by way of example, functions as an actuator in a control loop. In addition to the component 3, the control loop has a target value specification device 1, for example in the form of a cooling model for specifying a target pressure or a target volume flow, with which the coolant is to be fed to the application device 4 and applied on the rolled stock 20. The control loop provides that these target values are compared with the actual values for the pressure or volume flow determined by the pressure or volume flow meter 5 by forming the difference in order to determine a control deviation, which is fed into a controller 2. The controller 2 itself is used for outputting a control variable to the component 3 connected downstream of the controller 2, in particular a pump. The controller 2 is designed to form the control variable such that the current actual pressure or actual volume flow of the coolant is adjusted/controlled to the specified target pressure or target volume flow.
As an alternative to the control loop shown in FIG. 2 , the coolant can also simply be set to the specified target pressure or target volume flow as part of a control system. With the control system, unlike in the control loop, there is no feedback of the actual pressure or actual volume flow of the coolant in the line 12, as determined by the pressure or volume flow meter 5. For this reason, the dimensioning of the control variable is usually not carried out in accordance with a deviation between the target and actual data, but rather in accordance with empirical values.
Experience has shown that the component 3 does not remain in its original fault-free state during its service life in the cooling system 100, but is instead subject to contamination, deposits, corrosion and/or wear. This has the result that the component in its aforementioned used state will no longer exhibit the same control behavior as it does in a like-new/fault-free state.
FIG. 3 illustrates this different behavior of the component in the form of a comparison of a calibrated characteristic curve and an operating characteristic curve for the same component. For both characteristic curves, the flow rate Q over the valve opening y of the component is plotted by way of example in FIG. 3 . Thereby, the calibrated characteristic curve represents the target characteristic curve, which shows the optimum behavior of the component 3 in a like-new/fault-free state. In contrast, the operating characteristic curve of the same component in accordance with FIG. 3 is somewhat flatter. Unlike the calibrated characteristic curve, the operating characteristic curve represents the real behavior of the same component in a used state after a certain operating time/period of use. At least individual points on the calibrated characteristic curve are also referred to below as target characteristic data, while at least individual points on the operating characteristic curve are also referred to below as actual characteristic data. The operating characteristic curve is also referred to as the actual operating characteristic curve. The vertical difference in the diagram in FIG. 3 , i.e. the difference in the flow rate of the component at the same valve opening position between the calibrated characteristic curve and the operating characteristic curve, i.e. between the as-new state and the used state, is referred to below as the characteristic data deviation A.
For taking into account this changed setting behavior of the component, the cooling system 100 has an acquisition device 3 a for the current opening degree y of the component 3 and a characteristic data acquisition device 6 for determining at least individual points of the actual operating characteristic curve for the component 3.
As previously explained with reference to FIG. 3 , the operating characteristic curve comprises a diagram in which, for example, the actual flow rate Q/actual volume flow {dot over (V)} is plotted against the opening degree y of the component 3. Alternatively, for example, the actual pressure of the coolant can also be plotted against the opening degree of the component. The characteristic data acquisition device 6 is designed to generate at least individual points of this actual operating characteristic curve for the component as actual characteristic data in accordance with the actual pressure or actual volume flow acquired by the measuring device 5 and the particular associated acquired opening degree of the component.
Furthermore, the cooling system 100 has a comparison and evaluation device 7 for comparing the actual characteristic data from the characteristic data acquisition device 6 with target characteristic data representing at least individual points of a calibrated characteristic curve for the component. The Q(y) diagram in FIGS. 2, 4 and 5 shows, in each case, the target characteristic data/the calibrated characteristic curve. This comparison makes it possible to determine the characteristic data deviation A illustrated in FIG. 3 and allows this characteristic data deviation to be evaluated as to whether or not it exceeds a specified threshold value. Finally, the cooling system provides an output device 8 for outputting an indication or a warning to an operator of the cooling system 100 or to a signaling system if the characteristic data deviation Δ exceeds the threshold value. Alternatively, or in addition to this information, a fault derived from this can also be output.
Advantageously, however, the characteristic data deviation A is not only determined, but also used sensibly for the regulation or control of the component 3. This is achieved, for example, by introducing the characteristic data deviation, which, as already mentioned, represents the deviating behavior of the used component 3 with respect to the like-new, fault-free component, or a correction value calculated from it that is introduced as a disturbance variable to the open-loop or closed-loop controller 2. This disturbance variable introduction 9 enables the control device or controller 2 to determine a corrected control variable and output it to the component 3. Unlike the original uncorrected control variable, the corrected control variable takes into account the used state of the component and the resulting change in its setting behavior. In this manner, a more precise setting or regulating of the actual pressure or the actual volume flow of the coolant to the corresponding given target values is possible.
Alternatively, or additionally, the characteristic data deviation Δ or the correction value calculated from it can also be output to the target value specification device 1 as a disturbance variable. In this case, the target value specification device 1 also takes into account the setting behavior of the component 3 that has changed through use when calculating the target pressure or the target volume flow that is output to the open-loop or closed-loop controller 2. These two variants are illustrated in FIGS. 4 and 5 . FIG. 4 shows the introduction of the disturbance variable both to the open-loop or closed-loop controller 2 and to the target value specification device 1. FIG. 5 shows the disturbance variable introduction solely to the target value specification device 1.
The aforementioned characteristic data acquisition device 6 is not only suitable for determining at least individual points of the actual operating characteristic curve for the component 3 in its used state. Rather, the characteristic data acquisition device 6 is equally suitable for determining at least individual points of the calibrated characteristic curve for the component, namely if the component 3 is operated in its like-new/fault-free state in a system environment that is preferably also like-new/fault-free. These at least individual points of the calibrated characteristic curve, also known as target characteristic data, are typically measured during the commissioning of the cooling system and in particular the component.

LIST OF REFERENCE SIGNS

- 1 Target value specification device
- 2 Controller, control device
- 3 Component (=actuator), in particular valve, pump or spray nozzle
- 3 a Acquisition device for opening degree, volume flow, pressure of the component
- 4 Application device, in particular spray nozzle
- 5 Measuring device (pressure and/or volume flow)
- 6 Acquisition device for characteristic data/operating characteristic curve of the component;
- 7 Comparison and evaluation device
- 8 Outputting device
- 9 Disturbance variable introducing device
- Δ A Characteristic data deviation
- 10 Supply device for coolant
- 12 Line
- 20 Rolled stock
- 100 Cooling system
- Δ Characteristic data deviation
- y Valve opening degree
- Q Flow rate

Claims

1-15. (canceled)

16. A method for monitoring a component (3) of a cooling system (100) in a rolling mill, wherein the cooling system (100) is used to apply a coolant on a rolled stock (20) to be cooled, the method comprising:

specifying target characteristic data for the component (3), wherein the target characteristic data describe a calibrated behavior of the component (3) in a fault-free state during operation of the cooling system (100);

acquiring actual characteristic data for the component (3) during and/or after a period of use of the component (3);

comparing the actual characteristic data with the target characteristic data for the component (3) and determining a characteristic data deviation (Δ), which represents a malfunction of the component (3); and

taking a measure for minimizing the characteristic data deviation (Δ) if the characteristic data deviation (Δ) exceeds a predetermined threshold value.

17. The method according to claim 16,

wherein the measure comprises outputting a warning to an operator of the cooling system (100) or to a signaling system for checking the component (3).

18. The method according to claim 16,

wherein the cooling system (100) includes an open-loop or closed-loop controller (2),

wherein the component (3) is an actuator connected downstream of the open-loop or closed-loop controller,

wherein the method further comprises outputting a control variable to the actuator for setting or regulating an actual pressure or an actual volume flow with which the coolant is applied to the rolled stock (20) to a specified target pressure or target volume flow, and

wherein the measure comprises introducing the characteristic data deviation (Δ) or a correction value calculated from the characteristic data deviation (Δ) as a disturbance variable (9) to the open-loop or closed-loop controller (2) for determining a corrected control variable and for outputting the corrected control variable at an output of the open-loop or closed-loop controller (2) to the actuator (3).

19. The method according to claim 16,

wherein the cooling system (100) has an open-loop or closed-loop controller (2) with an upstream target value specification device (1),

wherein the component (3) is actuator for setting or controlling a pressure or a volume flow with which the coolant is applied on the rolled stock (20), and

wherein the measure comprises introducing the characteristic data deviation (Δ) or a correction value calculated from the characteristic data deviation (Δ) as a disturbance variable (9) to the upstream target value specification device (1) for adjusting a target value for the open-loop or closed-loop controller (2).

20. The method according to claim 16,

wherein at least some of

acquiring the actual characteristic data for the component (3),

comparing the actual characteristic data with the target characteristic data for the component (3) and determining the characteristic data deviation (Δ), and

taking the measure for minimizing the characteristic data deviation (Δ)

are repeated continuously during the operation of the cooling system (100) or during breaks in operation.

21. The method according to claim 16,

wherein the component (3) comprises a pump or a valve or a spray nozzle.

22. The method according to claim 16,

wherein the actual characteristic data comprise at least individual points of an actual operating characteristic curve of the component (3), which describes a behavior of the component (3) when used during the operation of the cooling system (100) during a time interval of its acquisition.

23. The method according to claim 16,

wherein the target characteristic data comprise at least individual points of a calibrated characteristic curve (10) of the component (3), which describes a behavior of the component (3) when like-new and fault-free in the operation of the cooling system (100) during a time interval of its acquisition.

24. A computer program product that can be loaded directly into an internal memory of a digital computer and comprises sections of software code with which the method according to claim 16 is carried out if the computer program product is running on the digital computer.

25. A cooling system (100) for cooling a rolled stock (20) in a rolling mill, comprising:

a supply device (10) for supplying a coolant for the cooling system (100) at a predetermined pressure;

a cooling section with a spray nozzle (4) for applying the coolant on the rolled stock (20);

a line (12) for feeding the coolant from the supply device to the spray nozzle (4);

a pressure or volume flow meter (5) for determining an actual pressure or an actual volume flow in the line;

a target value specification device (1) in form of a cooling model for specifying a target pressure or a target volume flow with which the coolant is to be applied on the rolled stock (20);

an actuator (3) selected from the group consisting of a pump, a valve, and the spray nozzle (5) in the line;

an open-loop or closed-loop controller (2) for outputting a control variable to the actuator (3) downstream of the open-loop or closed-loop controller for setting or regulating the actual pressure or the actual volume flow with which the coolant is applied on the rolled stock (20) to be cooled, to the specified target pressure or target volume flow;

an acquisition device (3 a) for an opening degree of the actuator (3);

a characteristic data acquisition device (6) for determining at least individual points of an actual operating characteristic curve for the actuator (3) as actual characteristic data in accordance with the actual pressure or the actual volume flow acquired by the pressure or volume flow meter (5) and the acquired opening degree of the actuator (3); and

a comparison and evaluation device (7) for comparing the actual characteristic data with target characteristic data which represent at least individual points of a calibrated characteristic curve for the actuator (3), for determining a characteristic data deviation (Δ) and for evaluating the characteristic data deviation (Δ) to determine whether the characteristic data deviation (Δ) exceeds a specified threshold value.

26. The cooling system (100) according to claim 25,

further comprising an output device (8) for outputting an indication or a warning to an operator of the cooling system (100) or to a signaling system that the characteristic data deviation (Δ) exceeds the specified threshold value and/or that the actuator (3) must be checked.

27. The cooling system (100) according to claim 25,

further comprising a disturbance variable introducing device (9) for introducing the characteristic data deviation (Δ) or a correction value calculated from it as a disturbance variable to the open-loop or closed-loop controller (2) for determining a corrected control variable and for outputting the corrected control variable at the output of the open-loop or closed-loop controller to the actuator (3).

28. The cooling system (100) according to claim 27,

wherein the disturbance variable introducing device (9) is designed for introducing the characteristic data deviation (Δ) or the correction value calculated from it as a disturbance variable to the target value specification device (1) for adjusting the target pressure or the target volume flow for the open-loop or closed-loop controller (2).

29. The cooling system (100) according to claim 25,

wherein the characteristic data acquisition device (6) is designed to acquire the calibrated characteristic curve of the actuator (3) if the cooling system (100) and the actuator (3) are in each case like-new or fault-free.