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

Abstract

The invention 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. In order to be able 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 according to the invention provides for the acquisition of actual characteristic data for the component during and / or after the period of use of the component 3. These actual characteristic data are compared with predetermined target characteristic data, in order to determine a possible characteristic data deviation Δ, which represents a malfunction of the component 3 with respect to its new state. The present invention then provides various measures for minimising the characteristic data deviation, if this exceeds a predetermined threshold value.

Description

[0001] Method, computer program and cooling system for monitoring a component of the cooling system in a rolling mill

[0002] The invention relates to a method and a computer program for monitoring a component of a cooling system in a rolling mill, wherein the cooling system with the component serves to apply a coolant to a rolling stock to be cooled. Furthermore, the invention also relates to the corresponding cooling system.

[0003] State of the art

[0004] Known cooling systems in rolling mills essentially consist of a cooling section with a plurality of spray nozzles supplied with a coolant via a system of pumps and valves. The coolant is preferably supplied 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 to the rolling stock to be cooled. Various components of the cooling system, such as the pumps, valves, or the spray nozzles themselves, serve as actuators.These control devices or control loops offer the advantage of dynamic and precise coolant application at a desired target pressure or flow rate. The use of speed-controlled pumps makes it possible to minimize pressure loss—and thus energy loss—generated by these actuators in the cooling system.

[0005] A large number of publications deal with the control and regulation systems described above and their optimization. One such publication is European patent application EP 3 495 056 A1. This document describes an operating method for a cooling line for cooling hot rolled metal stock, wherein the cooling line has a pump that draws coolant from a coolant reservoir and supplies the coolant via a system of lines to a number of coolant outlets, which are controlled by valves arranged upstream of the coolant outlets. The control device of the cooling line cyclically performs the following steps: Taking into account the coolant flows that are to be discharged via the coolant outlets at a given time, control states for the valves are determined in conjunction with the working pressure of the coolant present at the inlet side of the valves.By summing the coolant flows, a total coolant flow is determined. Taking into account the total coolant flow and the coolant's working pressure, a pump pressure is determined that should prevail on the pump inlet side so that the working pressure is reached on the valve inlet side. Taking into account the total coolant flow, the pump pressure, and a suction pressure prevailing on the pump inlet side, a control state for the pump is determined. The valves and pump are controlled according to the determined control states.In order to be able to provide the required amount of coolant at any time with high accuracy in an inefficient manner 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 for the respective time when determining the pump pressure.

[0006] Notwithstanding this state of the art, it is common practice to record a calibration curve for the actuators when commissioning a cooling system in order to be able to quickly adjust their operating points later. The calibration curve of the actuators, also called the basic characteristic curve, consists of target characteristics of the actuator that describe the calibrated behavior of the actuator in a wear- and fault-free condition during operation of the cooling system, which is preferably also wear- and fault-free. In practice, over time, contamination, deposits, corrosion, and wear occur 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 clogged, so that the maximum cooling water quantities can no longer be set.A uniform cooling of the rolled material across the width of the bench is then no longer possible and this may lead to quality losses during production.

[0007] All of these negative changes to the actuator or its surroundings are traditionally recorded in a so-called system characteristic curve, which can change over the course of the cooling system's operating life. The term "change in the system characteristic curve" is used below as a synonym for these negative changes.

[0008] For precise and current adjustment of a component or actuator in a cooling system, it is therefore necessary to know its current operating characteristic, which results from superimposing the basic characteristic with the system characteristic; see the lecture notes "Measurement and Control Engineering" of the Institute of Process Engineering at the University of Linz, Wälser Str. 42, 4060 Leonding / A.

[0009] Manual condition monitoring of the cooling system can usually only be carried out during a plant shutdown and is usually very labor-intensive, especially given the typical size of a cooling line in a rolling mill with a large number of actuators that need to be monitored with regard to their condition.

[0010] The invention is based on the object of developing a known method and computer program for monitoring a component of a cooling system in a rolling mill as well as a corresponding known cooling system with the component for applying a coolant to a rolling stock to be cooled in such a way that even if the system characteristic changes over time, the coolant is always applied to the rolling stock to be cooled at a desired target pressure or a desired target volume flow.

[0011] This object is achieved by the method claimed in patent claim 1. The purpose of the invention is to establish a preferably continuous condition monitoring of the components or actuators of cooling systems in a rolling mill. The method provides that during and / or after an operating time of the component or actuator of the cooling system, actual characteristic data for the component are recorded and subsequently compared with the previously determined or specified target characteristic data for the component. The actual characteristic data represent or include the actual condition of the component in its environment, including all potentially present negative changes. The target characteristic data, on the other hand, represent the component and its environment in a fault-free, in particular wear-free, condition. The comparison enables the determination of any characteristic data adjustment that represents or indicates a malfunction of the component.The process then stipulates that measures for minimization and adjustment are taken if the characteristic data deviation exceeds a predetermined threshold. Using the recorded actual characteristic data for the component and comparing it with the target characteristic data for the component, it is possible to determine the wear conditions on the component. This also allows reliable data to be determined for maintenance and repair. In this way, the rolling mill's production uptime can be increased by avoiding unplanned plant downtimes during production and shifting maintenance work to scheduled downtimes.

[0012] According to a first embodiment, the measure to be taken to minimize the characteristic deviation may be to issue a warning or an indication to an operator of the cooling system or to a reporting system for inspection and, if necessary, repair or replacement of the respective component.

[0013] An additional or alternative measure to minimize the characteristic data deviation can include: applying the characteristic data deviation or a correction value calculated from it as a disturbance variable to the control device or controller to determine a corrected manipulated variable and outputting the corrected manipulated variable to the component at the output of the control device or controller. This allows for even better consideration of a system characteristic curve that has changed over time when controlling the component.

[0014] According to a further measure, the characteristic data deviation or the correction value calculated from it can also be applied as a disturbance variable to a setpoint specification device, which is typically connected upstream of the control device or regulator. The applied characteristic data deviation or the correction value calculated from it is then used in the setpoint specification device to adjust the setpoint for the control device or regulator accordingly.

[0015] According to a further embodiment, at least some of the steps (b) to (d3) are repeated multiple times, preferably continuously, during operation of the cooling system or during periods of non-operation of the cooling system. With a high frequency of repetitions, even small changes in the system characteristic curve can be detected and taken into account when controlling the component or actuator.

[0016] The component is, for example, a pump, a valve or a spray nozzle within the cooling system.

[0017] The actual characteristics are at least individual points of a component's operating characteristic curve, which describes the behavior of the used component during operation of the cooling system at the time of recording. The term "used component" means that the component exhibits altered behavior compared to its new or fault-free condition due to signs of wear, for example, due to deposits or wear. The target characteristics of at least individual points of a calibrated characteristic curve of the component in fault-free condition are measured during operation of the cooling system, typically during commissioning.

[0018] The above-mentioned object of the invention is further achieved by a computer program product according to claim 9 and by a cooling system according to claim 10. The advantages of this solution correspond to the advantages mentioned above with regard to the said method.

[0019] The computer program product is a physical, distributable software product that includes software code sections as a program.

[0020] The description includes a total of 5 figures, where

[0021] Figure 1 shows the coolant side of the cooling system;

[0022] Figure 2 shows the control part of the cooling system according to a first embodiment;

[0023] Figure 3 shows a comparison of a calibrated characteristic curve and an operating characteristic curve of a component of the cooling system;

[0024] Figure 4 shows the control part of the cooling system according to the invention according to a second embodiment; and

[0025] Figure 5 shows the control-related part of the cooling system according to the invention according to a third exemplary embodiment. The invention is described in detail below with reference to the figures mentioned in the form of exemplary embodiments. In all figures, identical technical elements are designated by identical reference numerals.

[0026] Figure 1 shows the coolant-side part of the cooling system 100 according to the invention. The cooling system serves to cool a rolled stock 20 in a rolling mill. For this purpose, the cooling system has a supply device 10 to provide the coolant, preferably at a predetermined pressure, for cooling the rolled stock. The coolant is conducted via at least one line 12 from the supply device 10 to an application device 4, for example, a cooling beam with spray nozzles for applying the coolant to 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 supplied to the application device 4. A pressure or volume flow meter 5 is also installed in the line to determine the current actual pressure or actual volume flow of the coolant in the line.

[0027] The horizontal arrow to the left shown in Figure 1 indicates the flow direction of the coolant from the supply device 10 to the application device 4.

[0028] Figure 2 shows the control-technical part of the cooling system 100. It can be seen that component 3, here for example, functions as an actuator in a control loop. In addition to component 3, the control loop has a setpoint specification device 1, for example in the form of a cooling model for specifying a setpoint pressure or a setpoint volume flow with which the coolant is to be supplied to the application device 4 and applied to the rolling stock 20. The control loop provides that these setpoint values ​​are compared with the actual values ​​for the pressure or volume flow determined by the pressure or volume flow meter 5 by forming a difference in order to determine a control deviation, which is input into a controller 2. The controller 2 itself serves to output a manipulated variable to the component 3 connected downstream of the controller 2, in particular a pump.The controller 2 is designed to form the manipulated variable in such a way that the current actual pressure or actual volume flow of the coolant is adjusted or regulated to the specified target pressure or target volume flow.

[0029] As an alternative to the control loop shown in Figure 2, the coolant can also be simply adjusted to the specified target pressure or target flow rate within a control system. In contrast to the control loop, the control system does not provide feedback of the actual pressure or actual flow rate of the coolant in line 12 determined by the pressure or flow meter 5. Therefore, the dimensioning of the manipulated variable is generally not based on a deviation between the target and actual data, but rather based on empirical values.

[0030] Experience has shown that component 3 does not remain in its original, faultless condition during its service life in the cooling system 100, but rather is subject to contamination, deposits, corrosion, and / or wear. As a result, the component, in its said used condition, no longer exhibits the same control behavior as when it was in new or faultless condition.

[0031] Figure 3 illustrates this different behavior of the component by comparing a calibrated characteristic curve and an operating characteristic curve for the same component. For both characteristic curves, the flow rate Q is plotted against the valve opening y of the component as an example according to Figure 3. The calibrated characteristic curve represents the target characteristic curve, which shows the optimal behavior of component 3 in a new or fault-free condition. In contrast, the operating characteristic curve of the same component according to Figure 3 is somewhat flatter. The operating characteristic curve represents - unlike the calibrated characteristic curve - the actual behavior of the same component in a used condition after a certain period of operation or use. At least individual points on the calibrated characteristic curve are hereinafter referred to as target characteristic data, while at least individual points on the operating characteristic curve are hereinafter referred to 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 Figure 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 new and used condition, is referred to below as characteristic deviation A.

[0032] To take this changed adjustment behavior of the component into account, the present invention provides that the cooling system 100 has a detection device 3a for the respective current degree of opening y of the component 3 and a characteristic data detection device 6 for determining at least individual points of the actual operating characteristic curve for the component 3.

[0033] As previously explained with reference to Figure 3, the operating characteristic curve is a diagram in which, for example, the actual flow rate Q or actual volume flow V is plotted against the degree of opening y of component 3. Alternatively, for example, the actual pressure of the coolant can also be plotted against the degree of opening 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 detected by the measuring device 5 and the respectively associated detected degree of opening of the component.

[0034] Furthermore, the present invention provides that 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 desired characteristic data, which represent at least individual points of a calibrated characteristic curve for the component. The Q(y) diagram in Figures 2, 4, and 5 shows the desired characteristic data and the calibrated characteristic curve, respectively. This comparison enables the characteristic data deviation A illustrated in Figure 3 to be determined and allows this characteristic data deviation to be evaluated to determine whether or not it exceeds a predetermined threshold value. Finally, the cooling system according to the invention provides an output device 8 for outputting an indication or warning to an operator of the cooling system 100 or to a reporting system if the characteristic data deviation A exceeds the threshold value.Alternatively or in addition to this information, an error derived from it can also be output.

[0035] Advantageously, the characteristic data deviation A is not only determined, but also used effectively for the closed-loop or closed-loop control of component 3. This is achieved, for example, by applying the characteristic data deviation, which, as mentioned, represents the deviating behavior of the used component 3 compared to the new, fault-free component, or a correction value calculated from it as a disturbance variable to the control device or controller 2. This disturbance variable feedforward 9 enables the control device or controller 2 to determine a corrected manipulated variable and output it to component 3. Unlike the original, uncorrected manipulated variable, the corrected manipulated variable takes into account the used state of the component and its resulting changed setting behavior.In this way, a more precise setting or control of the actual pressure or the actual volume flow of the coolant to the corresponding given target values ​​is possible.

[0036] Alternatively or additionally, the characteristic data deviation A or the correction value calculated from it can also be output as a disturbance variable to the setpoint input device 1. In this case, the setpoint input device 1 takes into account the changed setting behavior of component 3 due to use when calculating the setpoint pressure or the setpoint volume flow, which is output to the control device or regulator 2. These two variants are illustrated in Figures 4 and 5. Figure 4 shows the feedforward of the disturbance variable to both the control device or regulator 2 and to the setpoint input device 1. Figure 5 shows the feedforward of the disturbance variable to the setpoint input device 1 alone.

[0037] 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 condition. 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 when the component 3 is operated in its new or fault-free condition in a preferably also new or fault-free system environment. These at least individual points of the calibrated characteristic curve, also called target characteristic data, are typically measured during commissioning of the cooling system and, in particular, the component.

[0038] List of reference symbols

[0039] 1 setpoint setting device

[0040] 2 controllers, control device

[0041] 3 Component (= actuator), in particular valve, pump or spray nozzle

[0042] 3a Detection device for opening degree, volume flow, pressure of the component

[0043] 4 Application device, in particular spray nozzle

[0044] 5 Measuring device (pressure and / or volume flow)

[0045] 6 Recording device for the characteristic data or operating characteristic of the component;

[0046] 7 Comparison and evaluation device

[0047] 8 Output device

[0048] 9 Disturbance feedforward device

[0049] A Characteristic data deviation

[0050] 10 Coolant supply device

[0051] 12 Line

[0052] 20 rolled goods

[0053] 100 Cooling system

[0054] A Characteristic data deviation y Valve opening degree

[0055] Q flow

Claims

Patent claims:

1. A method for monitoring a component (3) of a cooling system (100) in a rolling mill, wherein the cooling system (100) with the component (3) is used to apply a coolant to a rolling stock (20) to be cooled, and wherein the method comprises the following steps: a) specifying target characteristic data for the component (3), wherein the target characteristic data describe the calibrated behavior of the component (3) in a fault-free state during operation of the cooling system (100); b) recording actual characteristic data for the component (3) during and / or after a period of use of the component (3); c) comparing the actual characteristic data with the target characteristic data for the component (3) and determining a possible characteristic data deviation (A) that represents a malfunction of the component (3); and d) taking a measure to minimize the characteristic data deviation (A) if it exceeds a predetermined threshold value.

2. Method according to claim 1, characterized by the following measure according to method step d): d1) issuing a warning to an operator of the cooling system (100) or to a reporting system for checking the component (3).

3. Method according to one of the preceding claims, wherein the cooling system (100) has a control device or a regulator (2) each for outputting a manipulated variable to the component (3) as an actuator connected downstream of the control device or the regulator for setting or regulating the actual pressure or the actual volume flow with which the coolant is applied to the rolling stock (20) to be cooled, to a predetermined target pressure or target volume flow, at least in the case of regulation according to the characteristic data deviation (A), which represents the difference between the target characteristic data and the actual characteristic data; characterized by the following measure according to method step d): d2) applying the characteristic data deviation (A) or a correction value calculated therefrom as a disturbance variable in the sense of a disturbance variable feedforward (9) to the control device or the controller (2) for determining a corrected manipulated variable and for outputting the corrected manipulated variable at the output of the control device or the controller (2) to the component (3).Method according to one of the preceding claims, wherein the cooling system (100) has a control device or a regulator (2), each with an upstream setpoint specification device (1) and with the component (3) as a downstream actuator for setting or regulating the pressure or the volume flow with which the coolant is applied to the rolling stock (20) to be cooled, characterized by the following measure according to method step d): d3) applying the characteristic data deviation (A) or a correction value calculated therefrom as a disturbance variable in the sense of a disturbance variable application (9) to the setpoint specification device (1) for adapting the setpoint for the control device or the regulator (2). Method according to one of the preceding claims, characterized in that at least some of the steps b) to d3) are repeated several times, preferably continuously, during operation of the cooling system (100) or during operational breaks.Method according to one of the preceding claims, characterized in that the component (3) is a pump or a valve or a spray nozzle. Method according to one of the preceding claims, characterized in that the actual characteristic data are at least individual points of an actual operating characteristic curve of the component (3), which describes the behavior of the used component (3) during operation of the cooling system (100) during the time interval of their detection. Method according to one of the preceding claims, characterized in that the desired characteristic data are at least individual points of a calibrated characteristic curve (10) of the component (3), which describes the behavior of the new, fault-free component (3) during operation of the preferably likewise new and fault-free cooling system (100) during the time interval of their detection.A computer program product that can be loaded directly into the internal memory of a digital computer and comprises software code sections with which the steps according to the method according to one of the preceding claims are carried out when the product is run on the computer. Cooling system (100) for cooling a rolled stock (20) in a rolling mill, comprising: a supply device (10) for providing a coolant for the cooling system (100) at a predetermined pressure; a cooling section with at least one application device (4), in particular a spray nozzle, for applying the coolant to the rolled stock (20); at least one line (12) for supplying the coolant from the supply device to the application device (4); at least one pressure or volume flow meter (5) for determining the actual pressure or the actual volume flow in the line; a setpoint 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 applied to the rolling stock (20); at least one component (3), such as a pump, a valve and / or the spray nozzle (5) in the line; a control device or a regulator (2), each for outputting a manipulated variable to an actuator connected downstream of the control device or the regulator in the form of the component (3) for setting or regulating the actual pressure or the actual volume flow with which the coolant is applied to the rolling stock (20) to be cooled, to the specified target pressure or target volume flow, at least in the case of regulation according to a characteristic data deviation (A), which represents the difference between the target characteristic data and the actual characteristic data; characterized by a detection device (3a) for the degree of opening of the component (3);a characteristic data acquisition device (6) for determining at least individual points of the actual operating characteristic curve for the component (3) as actual characteristic data in accordance with the actual pressure or the actual volume flow detected by the measuring device (5) and the detected degree of opening of the component (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 component (3), for determining a characteristic data deviation (A) and for evaluating the characteristic data deviation (A) to determine whether it exceeds a predetermined threshold value. Cooling system (100) according to claim 10, characterized by an output device (8) for outputting an indication or a warning to an operator of the cooling system (100) or to a reporting system that the characteristic data deviation (A) exceeds the threshold value; exceeds and / or that the components (3) have to be checked. Cooling system (100) according to claim 10 or 11, characterized by a disturbance variable feedforward device (9) for feeding the characteristic data deviation (A) or a correction value calculated therefrom as a disturbance variable to the control device or the regulator (2) for determining a corrected manipulated variable and for outputting the corrected manipulated variable at the output of the control device or the regulator to the component (3). Cooling system (100) according to claim 10, 11 or 12, characterized in that the disturbance variable feedforward device (9) is further designed to feed the characteristic data deviation (A) or the correction value calculated therefrom as a disturbance variable to the setpoint specification device (1) for adapting the setpoint pressure or the setpoint volume flow for the control device or the regulator (2).Cooling system (100) according to one of claims 10 to 13, characterized in that the characteristic data acquisition device (6) is further configured to acquire the calibrated characteristic curve of the component (3) when the cooling system (100) and the component (3) are each in mint condition or fault-free. Cooling system (100) according to one of claims 10 to 14, characterized in that the cooling system is configured and configured to carry out the method according to one of claims 1 to 8.

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