Cooling system for rolling mills

Abstract

1. A method for cooling material in a cooling system of a rolling mill using a cooling fluid, the method comprising: conveying a length of material into the cooling system of the rolling mill by a transport mechanism; measuring a speed of the length of material by a sensor; comparing the measured speed to a setpoint speed by a control system, the setpoint speed having a corresponding first flow rate of the cooling fluid; calculating, by the control system, a second flow rate of the cooling fluid based on the comparison, the second flow rate being different from the first flow rate; and applying the cooling fluid at the second flow rate to the material in the cooling system.

Description

Technical Field

[0001] The present invention relates to a cooling system for rolling mills, including hot rolling mills and cold rolling mills.

Background Art

[0002] The production of material coils or plates typically involves the use of single-stand or multi-stand rolling mills. The final rolled product (i.e., the coil or plate) often needs to be passed through a cooling section to reduce the product temperature to the required target temperature. This is generally done by the application of water. The rate and accuracy at which the product temperature is reduced will affect the final mechanical properties of the product, namely the yield strength, tensile strength, and elongation.

[0003] Due to the length of the material, the product may be present in the rolling mill and the cooling section simultaneously. If the product is to be wound into a coil, the material may also be present in the coiler while being in the rolling mill and / or the cooling section. The speed at which the material progresses through the cooling section is fixed by the rolling mill or the coiler. During the cooling operation, the calculated water flow to be used by the cooling section will depend on the operating speeds of the rolling mill and the coiler. For example, a higher speed typically requires a higher water flow, and vice versa. The operating speed is predefined and known as the setpoint speed. This is supplied or set before the material passes through the cooling section to calculate the required water flow known as the flow reference.

[0004] In practice, the actual speed of the product may deviate from the setpoint speed for several reasons. Some of these reasons are as follows. a) The product may be present only in the rolling mill at a fixed speed that deviates from the initial setpoint speed. b) The product may be present in both the rolling mill and the coiler at a fixed speed that deviates from the initial setpoint speed. c) When the product leaves the rolling mill and is in the coiler alone, the loss of tension between the rolling mill and the coiler will result in a sudden change in speed. d) The product length may be such that the product is neither in the rolling mill nor the coiler, and therefore the product speed then depends on the speed of the roller table. e) If the product needs to be divided into smaller sections, for example using a flying crop shear (FCS), the product may be divided again, resulting in a loss of tension between the rolling mill, the product, and the coiler, thus causing a speed deviation.

[0005] Any deviation from the speed setpoint will result in a temperature error following cooling, ultimately causing the product to fall outside the temperature tolerance and thus resulting in changes in its mechanical properties over length. In particular, if the speed is higher than the original speed setpoint, the product will become hotter due to the reduced contact time with the coolant. Conversely, if the speed is lower than the original speed setpoint, the product will become colder due to the increased contact time with the coolant.

[0006] It is desirable to provide a method for cooling rolled products that reduces the effects of temperature fluctuations caused by changes in operating speed. [Overview of the project] [Means for solving the problem]

[0007] According to a first aspect, a method is provided for cooling a material in a cooling system of a rolling mill using a cooling fluid, the method comprising: transporting a material of a predetermined length into the cooling system of the rolling mill by a transport mechanism; measuring the speed of the material of the predetermined length by a sensor; comparing the measured speed with a setpoint speed by a control system, wherein the setpoint speed has a corresponding first flow rate of cooling fluid; calculating a second flow rate of cooling fluid by the control system based on the comparison, wherein the second flow rate is different from the first flow rate; and applying the cooling fluid to the material in the cooling system at the second flow rate.

[0008] The setpoint velocity can be the velocity at which the material is programmed to move through the cooling system, provided there are no factors that could interfere with this setpoint velocity. In this case, the cooling system can apply a first flow rate of cooling fluid to the material.

[0009] The result of the comparison can be a velocity difference, which can be considered as a change in velocity. The second flow rate is calculated based on the comparison and can be considered as an adjustment to the first flow rate that takes the velocity difference into account. Therefore, the control system can be considered to adjust the first flow rate to the second flow rate.

[0010] Therefore, the cooling method calculates the difference in material speed between the setpoint speed, which is the programmed operating speed of the rolling mill, and the actual speed at which the material moves through the rolling mill. This speed difference results in a temperature difference from the setpoint temperature after cooling, due to inadequate cooling of the material. For example, if the measured speed is higher than the setpoint speed, the material will become hotter due to reduced contact time with the cooling system. Conversely, if the measured speed is lower than the setpoint speed, the material will become colder due to increased contact time with the cooling system. By taking the speed difference into account, the amount of cooling fluid applied by the cooling system can be appropriately adjusted so that the contact time of the material with the cooling system is sufficient with respect to the speed at which the material is moving in order to cool the material to the desired temperature.

[0011] Preferably, the second flow rate is different from the first flow rate. In some cases, the second flow rate can be greater than the first flow rate. In other cases, the second flow rate can be less than the first flow rate. Thus, the first flow rate can be adjusted so that the cooling system applies more or less coolant depending on whether the measured speed is greater or less than the programmed operating speed.

[0012] The second flow rate may include a control value, which may be the result of a comparison between a measured velocity and a setpoint velocity. In some cases, the step of calculating the second flow rate includes adding the control value to the first flow rate to give the second flow rate. Preferably, the control value may be a value that minimizes the difference between the final temperature of a given length of material after that length has exited the cooling system and the setpoint temperature.

[0013] The method may further include the steps of: measuring the initial temperature of a predetermined length of material before it enters the cooling system using a first temperature sensor; comparing the measured temperature with a setpoint temperature; calculating a third flow rate based on the comparison using a control system; and combining the third flow rate with a second flow rate.

[0014] The result of comparing the measured temperature with the setpoint temperature can be the first temperature difference. The third flow rate can be calculated based on the comparison and considered as a flow rate adjustment that takes the temperature difference into account. Combining the third flow rate with the second flow rate can give the resulting flow rate.

[0015] The setpoint temperature can be the target final temperature of the material after cooling. Therefore, the control system can calculate how much coolant needs to be applied to cool the material from its initial temperature to the setpoint temperature. Based on this calculation, the control system can calculate the new flow rate corresponding to the amount by which the coolant flow rate needs to be adjusted to reach the target level of cooling. Thus, the cooling system applies more or less coolant according to the new flow rate, depending on the difference between the measured initial temperature and the setpoint temperature.

[0016] Preferably, the above method steps are carried out before applying the cooling fluid to the material according to a second flow rate. This allows both flow rates based on velocity difference and flow rates based on temperature difference to be taken into consideration before the cooling system applies the cooling liquid to the material.

[0017] The step of calculating the first flow rate may include: receiving a set of initial conditions related to the material by the control system; modeling the cooling process of the material by the control system and using the set of initial conditions; and calculating the first flow rate by the control system based on the modeled cooling process.

[0018] The initial state of a material can influence the rate at which it is cooled, and therefore the amount of liquid that needs to be applied to the material by the cooling system. The initial state of a material can be defined by a set of initial conditions. These initial conditions, while not limited to, can include the material's chemical composition and physical dimensions. Modeling can be carried out by a computer program model configured to run on a computing device as part of a control system. The model can use the initial conditions as input to model the cooling process of a particular material with a specific initial state. This can be used to calculate the flow rate of the cooling liquid that needs to be applied to the material to cool it to a setpoint temperature. Therefore, the cooling method can be adjusted and adapted to suit a wide variety of materials with a broad range of initial states.

[0019] Preferably, one set of initial conditions includes a setpoint temperature. The setpoint temperature can be considered as input to the model. This can help the modeling process to more accurately calculate how much liquid needs to be applied to the material to reach the target temperature, and thus calculate the appropriate flow rate.

[0020] Preferably, the first flow rate is combined with the second flow rate. This allows the cooling method to take into account the difference in rate, temperature, and the initial state of the material as the cooling system applies the cooling liquid to the material. Combining flow rates, for example, combining the first and second flow rates, may include the step of adding the first and second flow rates together.

[0021] The modeling step may further include: measuring the final temperature of a predetermined length of material after it has exited the cooling system using a second temperature sensor; comparing the measured final temperature with a predicted final temperature using a control system; and calculating the difference between the measured final temperature and the predicted final temperature using the control system, where the predicted final temperature is the final temperature predicted by the modeling process. The method may further include: modeling an enhanced cooling process of the material using a set of initial conditions and differences using a control system; calculating a fourth flow adjustment based on the modeled enhanced cooling process using the control system; and combining the fourth flow rate with the second flow rate.

[0022] Measuring the temperature of the material after it exits the cooling system indicates whether the material has been adequately cooled by the cooling system so that the setpoint temperature is substantially reached. The result of comparing the measured temperature with the predicted final temperature may be a second temperature difference. If the second temperature difference indicates that the final measured temperature differs from the setpoint temperature by a larger margin than an acceptable tolerance, the amount of cooling liquid applied to the material may be adjusted.

[0023] In this case, the second temperature difference can be an additional input to the model. The modeling process can be considered to take into account the performance of the cooling system for the previous length of the material and use this information as an input to subsequent modeling processes. That is, the model is informed about the actual level of cooling provided by the cooling system, and this information is used to more accurately model the cooling process of the material. In particular, the modeling process can calculate a more accurate flow rate of the cooling liquid that needs to be applied to subsequent lengths of the material by the cooling system based on the amount of cooling applied to the previous length of the material. Therefore, the modeling process can more accurately calculate how much liquid needs to be applied to the material to cool it to the setpoint temperature. Thus, the cooling method can be updated to take into account the real-time performance of the cooling system.

[0024] Preferably, the fourth flow rate is combined with the third flow rate. More preferably, the fourth flow rate is combined with the third and the second flow rates. This allows the cooling method to take into account the rate difference, the initial temperature difference, the initial state of the material, and the final temperature difference when the cooling system applies the cooling liquid to the material.

[0025] In some examples, the step of measuring the speed of a predetermined length of the material by a sensor includes the step of measuring the speed of a predetermined length of the material in the cooling system. In other examples, measuring the speed of a predetermined length of the material by a sensor includes measuring the speed of a predetermined length of the material before and / or after the cooling system. Generally, since the speed of the material will be the same at any point along the cooling section including before, during, and after cooling, the speed can be measured at any suitable first location. The reason is that this will also correspond to the material speed at another suitable location, for example, at a second and / or subsequent location.

[0026] The second flow rate can include a plurality of flow criteria. The cooling system can include a plurality of spray headers. The step of applying the cooling liquid at the second flow rate can include applying the cooling liquid to the material by each of the plurality of spray headers according to the corresponding flow criteria of the spray headers.

[0027] Thus, each spray header can be associated with different flow criteria, and thus each spray header can be configured to apply different amounts of cooling liquid to the material. This can enable the cooling system to finely adjust the cooling of the material by controlling the amount of liquid applied to the material along the length of the material.

[0028] According to another aspect, a system configured to cool a material in a rolling mill, the system including a transport mechanism configured to convey a predetermined length of the material into a cooling device of the rolling mill; a sensor configured to measure the speed of the predetermined length of the material; and a control system configured to compare the measured speed to a setpoint speed, the setpoint speed having a corresponding first flow rate of a cooling fluid; the control system configured to calculate a second flow rate of the cooling fluid based on the comparison, the second flow rate being different from the first flow rate; and the control system configured to apply the cooling fluid to the material in the cooling system at the second flow rate.

[0029] Preferably, the apparatus includes a first temperature sensor configured to measure an initial temperature of the predetermined length of the material before the predetermined length of the material is fed into the cooling system. The control system is further configured to compare the initial temperature to a setpoint temperature; further configured to calculate a third flow rate based on the comparison; and further configured to combine the third flow rate with the second flow rate.

[0030] In some examples, the control system is further configured to receive a set of initial conditions relating to a material; further configured to model a cooling process of the material using the set of initial conditions; and further configured to calculate a first flow rate based on the modeled cooling process.

[0031] The apparatus may further include a second temperature sensor configured to measure the final temperature of a predetermined length of material after that length has exited the cooling system. The control system may further be configured to compare the final temperature with a predicted final temperature; to calculate the difference between the measured final temperature and the predicted final temperature; to model an enhanced cooling process of the material using a set of initial conditions and differences; to calculate a fourth flow rate based on the modeled enhanced cooling process; and may further be configured to combine the fourth flow rate with the second flow rate.

[0032] In some cases, the sensor can be positioned within the cooling system.

[0033] Preferably, the cooling system includes a plurality of spray headers. Each spray header can be configured to apply a predetermined flow rate of cooling liquid to a predetermined length of material. Each flow header can be configured to apply a flow of liquid to a predetermined length of material at a second flow rate. [Brief explanation of the drawing]

[0034] [Figure 1] This is a schematic diagram of the cooling process. [Figure 2] This is a schematic diagram of another cooling process. [Figure 3] This is a diagram illustrating the steps of the cooling method. [Modes for carrying out the invention]

[0035] This disclosure relates to a method for cooling a material using a cooling system for a rolling mill that uses a cooling fluid, and to a corresponding system configured to carry out the cooling.

[0036] An exemplary cooling system 100 is shown overall in Figure 1. The cooling system 100 cools the sheet of material 6 rolled in the rolling mill 2 before the material is transformed into a final product. In some cases, to produce a final product, the sheet of material 6 is wound into a coil using, for example, a coiler 4 of an upcoiler. In other cases, the sheet of material 6 is divided into several smaller sections, which may be called plates, using, for example, a flying crop shear 5. The sheet of material 6 is optionally passed from the rolling mill 2 through the cooling system 100 to the coiler 4 using a transport mechanism (not shown). Typically, the transport mechanism takes the form of a series of rollers, on which the sheet of material 6 is placed, and the rotational movement of the rollers causes the material 6 to advance (from left to right in Figure 1) through various components of the rolling mill and cooling system 100. The material 6 is typically a metallic product, such as an elemental metal, or more generally, an alloy. In particular, metal products can be, for example, iron alloys such as steel or aluminum alloys.

[0037] The cooling system 100 includes a cooling device 102 and a control system 300, the cooling device 102 being configured to cool a material using a cooling fluid, and the control system 300 being configured to communicate with and control the cooling device 102. In particular, a sheet of material 6 is cooled by the cooling device 102, which is positioned to spray the cooling liquid onto the material 6 as it passes through the cooling system 100 via a transport mechanism. The specific form of the cooling liquid can vary depending on the type of material being cooled. For example, if material 6 is steel or steel-based, the cooling liquid is water. As another example, if material 6 is aluminum or aluminum-based, the cooling liquid is an oil-water mixture. In the example shown in Figure 1, the cooling device 102 includes a plurality of nozzles 101. The nozzles 101 spray the cooling liquid onto the outer surface of material 6 through the nozzles in order to cool material 6 using the cooling liquid. The plurality of nozzles can be divided into two groups. The first group of nozzles is located at the beginning of the cooling unit 102 and can be referred to as the spray header 103. The second group of nozzles is located at the end of the cooling unit 102 and can be referred to as the trim header 104.

[0038] The final temperature of the material sheet 6 is controlled by the cooling device 102 through the control of the amount of cooling liquid applied to the material 6 via various nozzles 101.

[0039] More specifically, the final temperature of material 6 is controlled using a combination of the initial temperature of the material 6 sheet when the material 6 sheet enters the cooling system 100 and the final temperature of the material 6 sheet when the material 6 sheet exits the cooling system 100. This can be referred to as feedforward control (using the initial temperature) and feedback control (using the final temperature). The trim headers 104 are configured to apply a fixed flow of cooling liquid to material 6, which is controlled as part of the feedback control loop. The fixed flow allows each trim header 104 to be either on or off, and when on, the flow of that trim header 104 is set to a fixed level. In other words, each trim header can either not apply cooling liquid or apply cooling liquid at a fixed flow rate. The spray headers 103 are configured to apply a variable flow of cooling liquid to material 6, which is controlled as part of the feedforward control loop. The variable flow allows each spray header 103 to be generally in the ON state, and the flow of that spray header 103 can be any flow rate from zero to the maximum flow rate. In other words, each spray header 103 can either not apply coolant or apply coolant at any flow rate up to the maximum flow rate. The feedforward control process and the feedback control process will be described in more detail later.

[0040] If no form of control loop (either feedforward control or feedback control) exists, the cooling system will apply the cooling fluid to the material at a first flow rate. The effect of including a control loop is to adjust the first flow rate to a new flow rate, generally different from the first flow rate, which will be applied to the material 6 by the nozzle 101. The new flow rate includes the first flow rate and the adjustment made to the first flow rate, the adjustment being referred to as the flow trim. The resulting new flow rate is referred to as the flow reference.

[0041] Several factors influence the amount of cooling liquid that needs to be applied to material 6 in order for the material to reach its final desired temperature (known as the setpoint temperature). These factors include various properties of material 6 (e.g., but not limited to, its chemical composition and physical dimensions), and the rate at which material 6 enters and passes through the cooling system 100. The first flow rate is calculated taking these factors into account.

[0042] These factors form part of a set of initial conditions 10 that are input into the cooling model 20 in the control system 300 to calculate the amount of cooling liquid defined by a first flow rate that will be applied to the material 6 by the cooling device 102. In particular, the cooling model 20 receives a set of initial conditions related to the material, and then, based on the initial conditions, models the physical cooling process to calculate the flow rate of cooling liquid required to be applied from the nozzle 101 by the cooling device 102. This calculated flow rate, calculated in the absence of any control loops, is the first flow rate. The first flow rate is passed from the cooling model 20 to the flow reference controller 40 in the control system 300.

[0043] To verify whether the amount of cooling liquid applied to material 6 is appropriate, such that the final temperature of the material after it exits the cooling system 100 is substantially the same as the setpoint temperature, within the industry-acceptable tolerance level of ±20 degrees Celsius, the temperature of material 6 after it exits the cooling system 100 is measured by a temperature sensor 108, which is in the form of a pyrometer and positioned between the cooling system 100 and the coiler 4. This temperature measurement can be referred to as the exit temperature.

[0044] The exit temperature is fed into a feedback controller 50, which forms part of the control system 300, and compares the exit temperature to the setpoint temperature. If the exit temperature differs from the setpoint temperature by more than the acceptable tolerance level, the cooler 102 is applying an inappropriate amount of coolant to the material, and therefore the flow rate of coolant from the nozzle 101 needs to be adjusted in some way. Any resulting temperature difference is used as part of the feedback control loop to adjust the control of the trim header 104. For example, if the exit temperature is too low compared to the setpoint temperature, it is necessary to apply less coolant to the material 6, and vice versa. The temperature difference is used to calculate the adjustment that needs to be made for the first flow rate. This adjustment can be referred to as a first temperature-based adjustment and is an example of a type of float trim. Other types of float trims are also possible, as will be discussed later.

[0045] The first temperature-based adjustment is sent to the flow reference controller 40, where it is combined with the first flow rate from the physical model 20 to give the resulting flow reference for the trim headers 104. The flow reference controller 40 controls the flow of the coolant from the trim headers 104 according to the flow reference, so that each trim header 104 can apply the same flow reference (i.e., the same amount) of coolant to the material 6. That is, the flow rate of all trim headers 104 in a group of trim headers 104 is the same across the group of trim headers 104. To adjust the flow rate of the coolant applied by the trim headers 104, the trim headers 104 can be switched on and off. In this case, each trim header 104 can be switched on and off independently of the other trim headers 104 in the group of trim headers, so that any number of trim headers 104 can be turned on. Therefore, by turning off some of the trim headers 104, it is possible to apply less coolant, and by turning on some of the trim headers 104, it is possible to apply more coolant. All trim headers 104 that are turned on apply coolant at the same flow rate, and therefore the amount of cooling depends on the number of trim headers 104 that are switched on at any given time.

[0046] The accuracy with which the physical model 20 calculates the flow criterion is improved and maintained by a heat transfer coefficient (HTC) adaptation process 70. This process 70 uses feedback in the form of exit temperature when the material leaves the cooling system 100. Based on the input 10, the HTC adaptation process 70 calculates the difference between the measured exit temperature and the exit temperature predicted by the physical model 20. This difference is fed back into the physical cooling model 10 so that it can be taken into account during subsequent modeling and calculations. Generally, this process can be thought of as modeling an enhanced cooling process for a material using both a set of initial conditions 10 and the calculated difference between the measured exit temperature and the predicted exit temperature. The calculated amount of cooling liquid to be applied by the cooling device 102 based on the enhanced physical model can be referred to as the fourth flow rate. This fourth flow rate is passed from the cooling model 20 to the flow criterion controller 40.

[0047] Furthermore, the amount by which material 6 needs to be cooled depends on the measured temperature of the material immediately before it enters the cooling system 100, compared to the setpoint temperature. A larger difference between the two temperatures will require more cooling, and vice versa.

[0048] Another temperature sensor 106, which is in the form of a pyrometer and is positioned between the cooling system 100 and the rolling mill 2, measures the temperature of the material just before it enters the cooling system 100. This temperature sensor 106 can be considered a first temperature sensor, and the previously described temperature sensor 108 can be considered a second temperature sensor.

[0049] The temperature measurement from the first temperature sensor 106, which may be referred to as the initial temperature or entry temperature, is input into the feedforward control 60, which is part of the control system 300. The feedforward control 60 compares the measured initial temperature to the setpoint temperature. Any resulting temperature difference is used as part of the feedforward control loop to adjust the control of the spray header 103. The temperature difference is used to calculate the adjustment that needs to be made for the first flow rate. This adjustment may be referred to as a second temperature-based adjustment and is another example of a type of float trim.

[0050] The second temperature-based adjustment is sent to the flow reference controller 40, where it is combined with the flow rate from the physical model 20 to give the resulting flow reference for the spray header 103. Thus, it is possible to think of the control system in general as calculating a third flow rate of the cooling liquid based on the result of the temperature comparison. Therefore, the second temperature-based adjustment can be thought of as the third flow rate. The flow reference controller 40 controls the flow of the cooling liquid from the spray header 103 according to this flow reference, where each spray header 103 can apply a different amount of cooling liquid to the material 6. That is, the flow rates of the spray headers 103 in multiple spray headers 103 can differ across the multiple spray headers 103.

[0051] Generally, the flow criterion sent from the flow criterion controller 40 and applied by the spray header 103 varies over a given time period, as the second temperature-based adjustment is not always the same. For example, in the first time period, there may be a large difference between the setpoint temperature and the initial measured temperature, which results in a large second temperature-based adjustment. However, in another time period, such as the second time period, there may be a small difference between the setpoint temperature and the initial measured temperature, which results in a small second temperature-based adjustment. By configuring the spray header 103 so that a variable flow rate can be applied to the material 6, it is possible to take into account different flow criterions resulting from different temperature differences.

[0052] More specifically, all spray headers 103 are generally on (rather than off). Therefore, the amount of cooling depends on the flow rate of each spray header 103. The entry temperature is measured and averaged with respect to segments of material having a predefined length, such as a segment of 1 m in length. The amount of liquid required to cool a segment of material is calculated to give a flow standard for the spray header 103 associated with a particular segment, as previously described. This calculation is repeated for each subsequent segment. The position of each segment passing through the cooling system 100 is tracked by the control system 300 so that the position of each segment of material relative to each spray header 103 is known at any given time. As each segment of material passes under a spray header 103, the flow standard calculated for that segment of material is applied by that particular spray header 103. As a segment of material moves through the cooling system 100 and passes under a subsequent spray header 103, the flow rate applied by the subsequent spray header 103 will be the flow standard calculated for that segment. As different segments of the material pass through the cooling system 100, different flow criteria are applied by the spray header 103, which are calculated for these different segments. Therefore, since the entry temperatures measured for each segment are generally different, the flow criteria calculated for each segment are different, and consequently, the flow rate applied by the spray header 103 changes as the material 6 passes through the cooling system 100.

[0053] As a result of the distance between the end of the cooling system 100 and the position where the second temperature sensor 108 is located, and therefore the position where the exit temperature is measured, an inherent delay exists in the temperature difference compensated by the control system 300. Consequently, there is a length of material whose temperature is outside the acceptable tolerance level, and this length corresponds to the distance from the cooling system exit and the exit temperature measurement position.

[0054] As can be seen in Figure 1, two control loops are used to calculate the flow rate of the cooling liquid. The first control loop includes a second temperature sensor 108, a feedback controller 50, and a flow reference controller 40 of the control system 300, which measures the temperature of the material 6 after it exits the cooling system 100 and uses this to perform several calculations to adjust the flow rate for each trim header 104. This control loop can be considered a feedback temperature control loop. The second control loop includes a first temperature sensor 106, a feedforward control 60, and a flow reference controller 40 of the control system 300, which measures the temperature of the material 6 before it enters the cooling system 100 and uses this to perform several calculations to adjust the flow rate for each spray header 103. This control loop can be considered a feedforward temperature control loop. Together, the feedback temperature control loop and the feedforward temperature control loop help ensure that the exit temperature of the material 6 is maintained at a substantially required setpoint temperature within an acceptable tolerance level.

[0055] During these calculations, it is assumed that the rate at which material 6 moves through the cooling system 100 matches the setpoint rate supplied to the cooling model 20, as part of the initial condition 10. However, as previously mentioned, the actual rate at which material 6 moves through the cooling system 100 is often different from this setpoint rate. This difference in rate can be referred to as a rate error. As a result of material 6 moving through the cooling system 100 at different rates, the flow rate of the cooling water applied to material 6 is not appropriate for the actual rate at which material 6 is moving. This is because the flow rate was calculated based on the setpoint rate that affects the exit temperature of material 6.

[0056] To improve the cooling of material 6 so that the exit temperature is substantially the same as the setpoint temperature, the difference in the velocity of material 6 must be taken into account when calculating the flow rate. This process will be illustrated with reference to Figure 2.

[0057] Figure 2 shows another exemplary cooling system 200 similar to Figure 1, with similar reference numbers representing similar features and processes, which will not be described again. A typical way of using the apparatus in Figure 2 is illustrated in Figure 3. The cooling device 202 of the cooling system 200 includes multiple nozzles 201. However, in this case, all nozzles 201 are spray headers 203, and there is no trim header 104. This is because this cooling system 200 does not include the feedback temperature control loop of Figure 1, which feeds the exit temperature back into the flow reference controller 40.

[0058] As before, and referring to Figure 3, in order to cool the material using a cooling fluid, the transport mechanism first transports a predetermined length of material into the cooling system of the rolling mill S300. During the cooling process, as the material 6 passes through the cooling system 200, a sensor measures the speed of the material over the predetermined length S302. In particular, the actual speed at which the material 6 moves through the cooling system 200 is repeatedly measured using at least one speed sensor 80. In some examples, the speed sensor 80 can take the form of one or more speed encoders on the transport mechanism over which the material 6 passes. In other examples, the speed sensor 80 can take the form of a laser speed device.

[0059] The velocity measured by the velocity sensor 80 is input into a velocity-related flow controller 90, which is part of the control system 500. The velocity-related flow controller compares the measured velocity to the setpoint velocity. In other words, the control system then compares the measured velocity to the setpoint velocity S304, where the setpoint velocity has a corresponding first flow rate of the cooling fluid associated with it. As previously discussed, if the velocity of material 6 passing through the cooling system 200 deviates from the setpoint velocity, the exit temperature will deviate from the desired setpoint temperature. Any resulting difference between the measured material velocity and the setpoint velocity can be considered a velocity error. In some cases, the velocity error will indicate that material 6 is moving faster than expected, and in other cases, the velocity error will indicate that material 6 is moving slower than expected. The resulting velocity difference is used to adjust the control of the spray header 203 as part of another feedforward control loop. The velocity difference is used to calculate the adjustments that need to be made to the first flow rate. This type of adjustment can be called velocity-based adjustment and is another example of a type of float trim. Velocity-based adjustment is the amount by which the resulting temperature difference is minimized. As the velocity error changes over time, the velocity-controlled flow rate also changes over time.

[0060] Generally, velocity-based adjustments are input into the feedforward control 260 and then sent to the flow reference controller 240, where they are combined with the flow rate from the physical model 20 to give the resulting flow reference for the spray header. Thus, generally, this process can be considered as the control system calculating a second flow rate (velocity-based adjustment) of the cooling fluid based on the comparison results S306, and then applying the cooling fluid to the material according to the second flow rate S308.

[0061] In most cases, the adjustments calculated as a result of both temperature comparison and velocity comparison are not considered separately but together. In this case, the velocity-based adjustment is input into the feedforward control 260, where it is combined with the temperature-based adjustment calculated based on the initial temperature to give the resulting feedforward adjustment. The resulting feedforward adjustment is another type of float trim.

[0062] The resulting feedforward adjustment is then sent to the flow reference controller 240, where it is combined with the flow rate from the physical model 20 to give the resulting flow reference for the spray header 203. The flow reference controller 240 controls the flow of the coolant from the spray header 203 according to this flow reference, where each spray header can apply different amounts of coolant to the material 6 in a manner similar to that described with reference to Figure 1. This means that the resulting flow reference compensates for errors in both temperature and velocity. Therefore, it is possible to consider that the feedforward control 260 plays a role in compensating for both temperature and velocity errors.

[0063] As can be seen in Figure 2, two control loops exist within the control system 500. The first control loop, which includes the first temperature sensor 106 of the control system 300, the feedforward control 260, and the flow reference controller 240, is substantially the same as the feedforward temperature control loop in Figure 1. Thus, this control loop is also a feedforward temperature control loop. This feedforward temperature control loop regulates the flow rate for each spray header 204. The second control loop includes the velocity sensor 80 of the control system 500, the velocity-related flow control 90, the feedforward control 260, and the flow reference controller 240. This second control loop measures the velocity at which the material moves through the cooling system 200 and uses this to perform several calculations to regulate the flow rate for all spray headers 204, so that the exit temperature of the material 6 is maintained at a substantially required setpoint temperature within an acceptable tolerance level. This second control loop can be considered a feedforward velocity control loop.

[0064] By using a combination of two feedforward control loops—namely, a feedforward temperature control loop and a feedforward velocity control loop—differences in both temperature and velocity are significantly reduced.

[0065] Further details on how changes in material rate are taken into account will be explained here.

[0066] The cooling model 20 is a physics-based model that models the cooling process within a material. Model 20 includes a finite difference temperature model and a microstructure model, including details of the heat transfer coefficient from the cooling liquid to the material (e.g., the heat transfer coefficient from water to steel). Model 20 can predict the change in material temperature as the material is cooled, and can also predict the final exit temperature at a second temperature sensor 108 after the material 6 exits the cooling system 200, based on inputs into the cooling model 20, including a first flow rate, setpoint velocity, and material properties (e.g., thickness, temperature, and chemistry).

[0067] The distance the material travels through the cooling section 200 is fixed by the length of the cooling section 200 and is known as the cooling distance. This is the distance traveled by the material 6 while it is being cooled. The length of time the material 6 is inside the cooling section 6, and therefore the length of time the material is being cooled, is known as the cooling time.

[0068] Since the cooling distance is fixed, any velocity error will result in a change in cooling time. This is because the material will be present in the cooling system 200 for a longer or shorter period of time. For example, if the velocity of the material increases from the setpoint, the cooling time decreases, and vice versa. Therefore, since a change in velocity is equivalent to a change in cooling time, the cooling time can be varied to calculate the effect of the change in velocity. The physical model 20 uses the cooling time (based on the setpoint velocity) to calculate how much heat will be removed from the material 6, and as a result, the exit temperature can be predicted by the model 20. To account for velocity variations, by applying a small deviation to the cooling time for the nominal set conditions, the rate of change in the material exit temperature with respect to velocity can then be calculated by the physical model 20.

[0069] Furthermore, fluctuations in the flow rate of the cooling liquid result in a change in the rate of heat removal from the surface of material 6. For example, a high flow rate corresponding to a large flow criterion leads to a high rate of heat removal from the material, and therefore the material is cooled rapidly. Conversely, a low flow rate corresponding to a small flow criterion leads to a low rate of heat removal from the material, and therefore the material is cooled slowly. Thus, a change in flow rate that causes a change in the rate of heat removal causes a change in the material's exit temperature. The relationship between the change in flow rate and the change in exit temperature can be determined and taken into account by physical model 20. In order to take into account fluctuations in the flow rate of the cooling liquid, the rate of change in material exit temperature with respect to flow rate can be calculated by the physical model by applying a small deviation to the flow rate for a nominal set of conditions.

[0070] By combining the relationship between velocity and exit temperature with the relationship between flow rate and exit temperature, the relationship between flow rate and velocity can be calculated as follows.

[0071] Physical model 20 generates two relationships using nominal conditions. The first relationship is the rate of change of temperature (i.e., exit temperature) at the second temperature sensor 108 with respect to a change in material velocity, given by dT / dv, where T is the temperature in Celsius and v is the velocity in meters per second. The second relationship is the rate of change of temperature (i.e., exit temperature) at the second temperature sensor 108 with respect to the flow rate of the cooling liquid from the nozzle, given by dT / dF, where T is the temperature in Celsius and F is the flow rate in liters per second.

[0072] These two relationships can be combined to give the rate of change of flow rate in response to a change in velocity, as follows:

[0073]

number

[0074] Here, the change in flow rate dF (in liters per second) is given by the following:

[0075]

number

[0076] Therefore, Model 20 makes it possible to predict what changes in exit temperature will occur when the material rate is changed by a specific percentage. The flow rate can then be adjusted to compensate for any overcooling or undercooling that may result from the rate change. The flow rate change applies to all spray headers 203. This means that the proportional change in flow rate is the same in each spray header 203 because the instantaneous change in material rate is the same for each spray header 203.

[0077] The use of two feedforward control loops compensates for rate and temperature fluctuations that occur during the process. The main steps of the control process are as follows: a) A step of measuring the velocity error by comparing the setpoint velocity of the material with the actual measured velocity. b) A step of calculating the variation in exit temperature due to velocity and the variation in exit temperature due to flow rate. c) A step of combining the calculated fluctuations to give a velocity-dependent flow rate variation, which is a change in flow rate required to compensate for the velocity fluctuation. d) A step of calculating the float trim as a result of the change in velocity and applying that float trim to the float trim calculated as a result of the feedforward temperature control loop. e) A step of adjusting and maintaining the flow rate in an updated flow reference supplied by a feedforward controller, based on the flow trim received from the feedforward temperature control loop and the feedforward velocity control loop.

[0078] In summary, the cooling systems and processes described herein provide improved temperature performance of the material being cooled, which results in a reduction of out-of-tolerance products and, therefore, a reduction in operating costs. [Explanation of symbols]

[0079] 2 Rolling mill 4 Coilers 5 Flying Cropsshire 6 Materials 10 inputs 20. Physical models, cooling models 40 Flow-Based Controller 50 Feedback Controllers 60 Feedforward control 70. Heat Transfer Coefficient (HTC) Compliant Process 80 Speed ​​Sensor 90. Flow control related to speed 100 Cooling System 101 Nozzles 102 Cooling device 103 Spray Header 104 Trim Header 106 First temperature sensor 108 Second temperature sensor 200 Cooling System 201 Nozzle 202 Cooling device 203 Spray Header 240 Flow-Based Controller 260 Feedforward control 300 Control Systems 500 Control Systems

Claims

1. A method of cooling a material in the cooling system of a rolling mill using a cooling fluid, The transport mechanism involves the steps of conveying a material of a predetermined length into the cooling system of the rolling mill; The steps include: measuring the speed of the material of a predetermined length using a sensor; The control system comprises the steps of comparing the measured speed with a setpoint speed, which is the programmed operating speed of the rolling mill, wherein the setpoint speed has a corresponding first flow rate of the cooling fluid; The control system calculates a second flow rate of the cooling fluid based on the comparison, wherein the second flow rate is different from the first flow rate; The steps include applying the cooling fluid to the material in the cooling system at the second flow rate, and Includes, The second flow rate includes a control value, the control value being the result of the comparison between the measured velocity and the setpoint velocity, and the step of calculating the second flow rate includes adding the control value to the first flow rate to give the second flow rate. The adjustment value is a value that minimizes the difference between the final temperature of the material of the predetermined length after it has left the cooling system and the set point temperature, which is the target final temperature of the material after cooling. The step of calculating the first flow rate is: The control system takes the step of receiving a set of initial conditions related to the material; The steps include: modeling the cooling process of the material using the control system and the set of initial conditions; The control system includes the step of calculating the first flow rate based on the modeled cooling process, The aforementioned modeling step is, A second temperature sensor measures the final temperature of the material of a predetermined length after it has left the cooling system; The control system includes the steps of comparing the measured final temperature with the predicted final temperature; The control system includes the steps of: calculating the difference between the measured final temperature and the predicted final temperature; A step of modeling an enhanced cooling process for the material using the aforementioned set of initial conditions and the aforementioned difference; The control system includes the steps of calculating a fourth flow rate for flow rate adjustment that takes the difference into account, based on the enhanced cooling process modeled by the control system; A method further comprising the step of adding a fourth flow rate for flow rate adjustment to the second flow rate.

2. The aforementioned method, A first temperature sensor measures the initial temperature of the material of a predetermined length before it enters the cooling system; The steps include: comparing the measured temperature with the setpoint temperature; The control system includes the steps of calculating a third flow rate for flow rate adjustment, taking into account the difference between the measured temperature and the setpoint temperature, based on the comparison; The steps include adding the third flow rate for flow rate adjustment to the second flow rate, The method according to claim 1, further comprising:

3. The method according to claim 1, wherein the step of measuring the velocity of the material of a predetermined length by a sensor includes the step of measuring the velocity of the material of a predetermined length in the cooling system.

4. The second flow rate includes a plurality of flow criteria, the cooling system includes a plurality of spray headers, and the step of applying the cooling fluid at the second flow rate is, The step of applying the cooling fluid to the material by each of the plurality of spray headers according to the corresponding flow criteria of the spray headers. The method according to claim 1, including the method described in claim 1.

5. A cooling system configured to cool material inside a rolling mill using a cooling fluid, A transport mechanism configured to transport material of a predetermined length into the cooling unit of a rolling mill; A sensor configured to measure the speed of a material of a predetermined length; Control system and Includes, The control system is configured to compare the measured speed with a setpoint speed, which is the programmed operating speed of the rolling mill, the setpoint speed having a corresponding first flow rate of the cooling fluid; The control system is configured to calculate a second flow rate of the cooling fluid based on the comparison, wherein the second flow rate is different from the first flow rate; The control system is configured to apply the cooling fluid to the material in the cooling system at the second flow rate, The second flow rate includes a control value, the control value being the result of the comparison between the measured velocity and the setpoint velocity, and the step of calculating the second flow rate includes adding the control value to the first flow rate to give the second flow rate. The adjustment value is a value that minimizes the difference between the final temperature of the material of the predetermined length after it has left the cooling system and the set point temperature, which is the target final temperature of the material after cooling. The control system is It is configured to receive a set of initial conditions related to the aforementioned material; The system is configured to model the cooling process of the material using the aforementioned set of initial conditions; It is configured to calculate the first flow rate based on the modeled cooling process, The cooling system further includes a second temperature sensor configured to measure the final temperature of a predetermined length of material after the material has left the cooling system; The control system is The system is further configured to compare the aforementioned final temperature with the predicted final temperature; It is further configured to calculate the difference between the measured final temperature and the predicted final temperature; It is further configured to model an enhanced cooling process for the material using a set of initial conditions and the aforementioned difference; Based on the modeled enhanced cooling process, it is further configured to calculate a fourth flow rate for flow rate adjustment taking the difference into account; A cooling system further configured to add a fourth flow rate for flow rate adjustment to the second flow rate.

6. The cooling system further includes a first temperature sensor configured to measure the initial temperature of a predetermined length of material before that length is fed into the cooling system; The control system is The system is further configured to compare the initial temperature with the setpoint temperature, which is the target final temperature of the material after cooling; Based on the above comparison, it is further configured to calculate a third flow rate for flow rate adjustment that takes into account the difference between the initial temperature and the setpoint temperature; The cooling system according to claim 5, further configured to add the third flow rate for flow rate adjustment to the second flow rate.

7. The cooling system according to claim 5, wherein the sensor is located within the cooling system.

8. The cooling system according to claim 5, wherein the cooling system includes a plurality of spray headers.

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