Cooling of rolled products upstream of the finishing train of a hot rolling mill

Abstract

The invention relates to a method for cooling a rolled product (15) in a cooling section (19) located upstream of a finishing train (9) of a hot rolling mill (1), the cooling section (19) comprising at least one cooling device (21, 22, 23) capable of providing a coolant flow rate of a coolant (35) onto the rolled product surface (29) of the rolled product (15). In the method, a coolant flow rate is provided by each cooling device (21, 22, 23) onto the rolled product surface (29) in each cooling section pass, the coolant flow rate being set to a setpoint assigned to the associated cooling device (21, 22, 23) of the cooling section pass. The setpoint for a cooling section pass is determined in a simulation of the cooling section pass, such that the surface temperature of the rolled product surface (29) upon leaving the effective area (31, 32, 33) of the cooling device (21, 22, 23) determined in the simulation does not exceed a minimum surface temperature of the rolled product surface (29).

Description

Technical Field

[0001] The present invention relates to a method and a cooling section for cooling a rolled product upstream of the finishing train of a hot rolling mill.

Background Art

[0002] In a hot rolling mill, a metal rolled material such as a steel strip is rolled to reduce its thickness. The hot rolling mill often has a so-called roughing train and a so-called finishing train. In the roughing train, the rolled material is rolled into a so-called transfer bar having a transfer bar thickness. The transfer bar is supplied to the finishing train via a so-called intermediate roller table, where the thickness of the rolled product is further reduced from the transfer bar thickness to the final thickness.

[0003] The rolled material is supplied to the roughing train at a temperature in the range of, for example, 1100°C to 1200°C. For example, the rolled material is heated to this temperature in a heating furnace before the roughing train, or the already heated rolled material is directly supplied to the roughing train. In the intermediate roller table, the rolled product is not reformed. That is, the thickness does not decrease due to rolling, and the rolled product is simply cooled. That is, the temperature of the transfer bar drops to a temperature in the range of, for example, 700°C to 900°C.

[0004] Cooling the rolled product in the intermediate roller table serves to limit the inlet temperature of the rolled product when entering the finishing train. The inlet temperature is restricted for metallurgical reasons, particularly in the production of so-called thermomechanically rolled products such as tubular steel and microalloy steel, to suppress recrystallization of the rolled product during conveyance of the rolled product through the finishing train, and / or to achieve high surface quality in the production of automotive outer skins and can sheet metal, etc. Furthermore, when conveying the rolled product through the intermediate roller table, it is often advantageous to achieve the desired inlet temperature of the finishing train as soon as possible.

[0005] On the one hand, excessive cooling of the rolled product on the intermediate roller table may cause insufficient cooling of the surface area of the surface of the rolled product. In the area close to the surface of the rolled product, such supercooling causes a phase transformation and may impair the quality of the product manufactured during the rolling process, so it is necessary to avoid it. In order to prevent such supercooling, it is necessary that the surface temperature of the surface of the rolled product on the intermediate roller table does not fall below a certain minimum value.

[0006] Patent Document 1 discloses an operating method for cooling a flat rolled product in a cooling section provided with a cooling device arranged along the cooling section, and a coolant can be supplied onto the rolled product from each cooling device when the rolled product passes through the cooling section. The cooling capacity of the cooling device is determined by simulating the conveyance of the points of the rolled product passing through the cooling section, and the cooling device is controlled according to these cooling capacities during the conveyance of the rolled product passing through the cooling section.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Non-Patent Documents

[0008]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] The object of the present invention is to provide a method and a cooling section for cooling a rolled product upstream of the finishing train of a hot rolling mill, which cool the rolled product so that the surface temperature of the rolled product surface of the rolled product does not fall below a predetermined minimum value.

Means for Solving the Problems

[0010] According to the present invention, this object is achieved by a method having the features of claim 1 and a cooling section having the features of claim 13.

[0011] Advantageous embodiments of the present invention are the subject matter of the dependent claims.

[0012] In the method according to the present invention, the rolled product is cooled in the cooling section, the cooling section is arranged upstream of the finishing train of the hot rolling mill, and the rolled product is conveyed once through the cooling section along the cooling section path at a predetermined conveying speed, or several times in alternating directions at a predetermined conveying speed each time. The predetermined conveying speed may change over time. However, it may be constant over time. The cooling section has one cooling device having an effective area, or a plurality of cooling devices arranged one after another along the cooling section path, each having an effective area, and the effective areas of adjacent cooling devices are directly adjacent to each other. By each cooling device in each effective area, the coolant flow rate of the coolant can be supplied onto the rolled product surface of the rolled product, and the coolant flow rate can be set between a value of zero and a maximum value specific to the cooling device.

[0013] In the method according to the present invention, during the conveyance of the rolled product through the cooling section, a minimum value of the surface temperature of the rolled product surface is accepted. In order to maintain the minimum value, for each passage through the cooling section, a set value of the coolant flow rate is assigned to each cooling device, and the coolant flow rate is sent onto the rolled product surface by each cooling device for each passage through the cooling section, and the coolant flow rate is set to the set value assigned to the relevant cooling device for the passage through the cooling section.

[0014] To determine the set values for passing through the cooling section, at least one simulation of passing through the cooling section is performed on the rolled product section of the rolled product passing through the cooling section at a predetermined conveying speed. For each pass through the cooling section by simulation, the following values are continuously determined for each cooling device. - The default value of the coolant flow rate supplied by the cooling device is received or determined at the latest immediately before the rolled product section enters the effective area of the cooling device. - Based on the initial enthalpy distribution and / or initial temperature distribution of the rolled product section when entering the effective area of the cooling device, a physical model is used to calculate the enthalpy distribution and / or temperature distribution of the rolled product section when exiting the effective area of the cooling device. - The set value is such that the set value does not exceed the default value, and the surface temperature of the rolled product surface derived from the initial enthalpy distribution and / or initial temperature distribution, or the surface temperature of the rolled product surface derived from the calculated enthalpy distribution and / or calculated temperature distribution of the rolled product section, does not fall below the minimum value when exiting the effective area of the cooling device. The coolant flow rate supplied from the cooling device to the rolled product surface is determined to be quasi-maximized under these secondary conditions.

[0015] During the simulation of passing through the cooling section, for each two effective areas that the rolled product part continuously passes through immediately after passing through the cooling section, when exiting the first effective area passed through, the enthalpy distribution and / or calculated temperature distribution calculated for the first effective area passed through are further assigned to other effective areas as the initial enthalpy distribution and / or initial temperature distribution when entering the other effective areas. The original initial enthalpy distribution and / or original initial temperature distribution are accepted for the first cooling device through which the rolled product section passes during passing through the cooling section.

[0016] Therefore, in the method according to the invention, each passage of the rolling product through the cooling section is first simulated at least once for the rolling product section of the rolling product, and the set values of the coolant flow rates of all the cooling devices are determined during the simulation. These set values are used to control the cooling devices during the actual passage of the rolling product through the cooling section. The set values of the cooling devices are such that, during the simulation of the passage through the cooling section, the coolant flow rate determined by the set value does not exceed the default value, and the surface temperature of the rolling product surface determined during the simulation does not fall below the minimum value when exiting the effective region of the cooling device, and is determined to be quasi-maximal under these secondary conditions. The default value of the coolant flow rate of the cooling device is determined during the simulation or received, for example, from a higher-level control system.

[0017] The quasi-maximal coolant flow rate here is understood to be the coolant flow rate that is maximal under the specified secondary conditions or approximates the maximal coolant flow rate as part of the control design. This is because the simulation is based on a mathematical model that only models the cooling section, and therefore does not accurately represent the cooling section. So, in practice, it is not necessary to accurately maximize the coolant flow rate. Thus, it takes into account that any slight deviation of the simulation from the actual cooling process in the cooling section must be accepted anyway. Furthermore, accurately maximizing the coolant flow rate requires an unduly high computational effort and may prevent the simulation from being executed as quickly as possible.

[0018] By quasi-maximizing the coolant flow rate, there is an advantage that the cooling of the rolled product can be optimized during conveyance through the cooling section. Using the default value of the set value of the coolant flow rate, the target temperature at the end of the cooling section of the rolled product can be specified, and this temperature is adapted to the desired inlet temperature of the rolled product at the time of entry into the finishing train. The secondary condition that the surface temperature of the rolled product surface determined during the simulation does not fall below the minimum value of the surface temperature when exiting the effective region of the cooling device occurs during the conveyance of the rolled product through the cooling section, and advantageously prevents the above-described overcooling of the rolled product surface where the quality of the product deteriorates. Therefore, the minimum value is set so that such overcooling of the rolled product surface does not occur.

[0019] In one embodiment of the method according to the invention, for each passage of the rolled product section through the cooling section by simulation, at least one cooling device, in particular each cooling device,

Number

Number

Number

Number

Number

Number

[0020] In the foregoing embodiment of the method according to the present invention, the secondary condition that the set value does not exceed the default value is realized in that the function f i (T) does not exceed the value 1. The secondary condition that the surface temperature of the rolled product surface does not fall below the minimum value when exiting the effective region of the cooling device is the preliminary temperature difference [Number] can be achieved by appropriately selecting. The quasi-maximization of the coolant flow rate is achieved by monotonically increasing the function f i (T) from 0 to 1.

[0021] In an embodiment of the method according to the present invention that replaces the foregoing embodiment, first, the surface temperature of the rolled product surface when exiting the effective region of the cooling device is calculated for the default value of the coolant flow rate of the cooling device, so that the set value of at least one cooling device, in particular each cooling device, is determined for each pass through the cooling section by simulation. If the surface temperature calculated for the default value does not fall below the minimum value, the set value is set equal to the default value. Otherwise, in order to determine the set value of the coolant flow rate at which the calculated surface temperature when exiting the effective region coincides with the minimum value with sufficient accuracy, the calculation of the surface temperature when exiting the effective region is repeated for at least one coolant flow rate smaller than the default value. A sufficiently accurate coincidence is understood to mean, for example, a coincidence in which the quantity does not exceed a specified tolerance value, except for absolute or relative deviations.

[0022] The above-described embodiments of the method according to the invention also fulfill the above-described secondary conditions. This embodiment achieves an exact maximization of the coolant flow rate if the surface temperature actually corresponds to the minimum value after the iterative calculation. However, slightly exceeding the minimum value is allowed for the reasons stated above and means that the coolant flow rate is quasi-maximized.

[0023] In a further embodiment of the method according to the invention, for each cooling device, the maximum value of the coolant flow rate specific to the associated cooling device is accepted as the default value of the coolant flow rate for each pass through the cooling section by simulation.

[0024] The above-described embodiments of the method according to the invention enable, in particular, cooling the rolled product as quickly as possible during passage through the cooling section by setting each default value to the maximum value of the coolant flow rate specific to the associated cooling device.

[0025] In one embodiment of the method according to the invention, as an alternative to the above-described embodiments, for the simulation of the passage of the rolled product section through the cooling section, the total coolant amount of the coolant supplied in total to the surface portion of the surface of the rolled product belonging to the rolled product section during passage through the cooling section is determined, and the default value of the coolant flow rate for the passage of the cooling section by simulation is determined according to the total coolant amount specified for the passage of the cooling section and the conveying speed. The term "coolant amount" always means the integral of the coolant flow rate during the operating time of the rolled product section under consideration through the effective area of one or more cooling devices. It is possible that the coolant flow rate acting on the rolled product section does not always have the same effect. In this case, the coolant amount refers to the integral weighted according to the cooling effect of the coolant flow rate. The physical unit of the coolant flow rate corresponds, for example, to m 3 / s for a specific coolant flow rate (m 2 / s) per meter of width of the cooling device. The physical unit of the coolant amount is m 2 and corresponds to the coolant amount per meter of width of the cooling device (m 3 ).

[0026] In the foregoing embodiments of the method according to the invention, the cooling effect throughout the passage through the cooling section, and thus the target temperature of the rolled product after passage through the cooling section, can be determined in advance by the total coolant quantity. The default value of the coolant flow rate for the simulated passage through the cooling section is determined as a function of the total coolant quantity, and the total coolant quantity is distributed to the cooling devices according to the default value.

[0027] In a development of the above-described embodiment of the method according to the invention, the target average temperature of the rolled product is received after passage through the cooling section. In each simulation of the passage of the rolled product section through the cooling section, the average temperature of the rolled product section at the end of the passage through the cooling section is calculated, and if the calculated average temperature does not correspond sufficiently accurately to the target average temperature, the total quantity of coolant is changed for subsequent simulations of the passage of the rolled product section through the cooling section in order to bring the calculated average temperature into agreement with the target average temperature. This has the advantage that it is possible to repeatedly change the total coolant quantity in order to achieve the target average temperature with sufficient accuracy at the end of the passage through the cooling section. A sufficiently accurate agreement between the calculated average temperature and the target average temperature is understood to mean, for example, an agreement in which the quantity, apart from an absolute or relative deviation, does not exceed a specified tolerance value. In this further design, the target average temperature of the rolled product after passage through the cooling section is specified as the target temperature of the rolled product, and the total quantity of coolant is adjusted in accordance with the target average temperature.

[0028] Furthermore, during the simulation of the passage of the rolled product section through the cooling section, a residual coolant quantity may be allocated to each cooling device. The total coolant quantity is allocated as the residual coolant quantity to the first cooling device of the passage through the cooling section. To each further cooling device there is allocated, as the residual coolant quantity, the residual coolant quantity of the preceding cooling device minus the quantity of coolant supplied by the preceding cooling device in accordance with the coolant flow rate setting value determined for the surface portion of the rolled product surface belonging to the rolled product section for the preceding cooling device of the passage through the cooling section. Thus, the default value of the coolant flow rate of the cooling device is

Number

Number

Number

Number

Number

Number

Number

[0029] Alternatively, if during the simulation of the passage of the rolled product section through the cooling section, a set value smaller than the default value received for the cooling device is determined for the cooling device, and if there is at least one subsequent cooling device that is reached later during the passage through the cooling section and the received default value is smaller than the maximum value of the coolant flow rate of this cooling device, in order to adapt the total amount of coolant supplied to the surface portion of the surface of the rolled product belonging to the rolled product section during the passage through the cooling section to the total amount of coolant determined for the passage through the cooling section, the default value of at least one such subsequent cooling device may be increased. This embodiment of the method according to the invention is based on the default value received at the start of the simulation. If the set value determined for the cooling device during the simulation is below the relevant default value, the default value is adjusted during the simulation as necessary. When adapting the default value, if possible, the default value of the subsequent cooling device is increased in order to adapt the cooling effect of the passage through the cooling section to the cooling effect corresponding to the total coolant amount.

[0030] In a further embodiment of the method according to the invention, during the simulation of the passage of the rolled product section through the cooling section, a one-dimensional heat conduction equation describing the enthalpy distribution and / or temperature distribution of the rolled product section along the thickness direction of the rolled product is solved in order to calculate the enthalpy distribution and / or temperature distribution of the rolled product section when exiting the effective area of the cooling device. In order to solve the heat conduction equation, boundary conditions are considered that parameterize, for example, the cooling of the rolled product section by thermal radiation, the coolant supplied to the surface of the rolled product, the heat dissipated to the ambient air, and the heat dissipated to the conveyor rollers transporting the rolled product. The thickness direction of the rolled product is the direction from the upper surface to the lower surface of the rolled product, or the reverse direction from the lower surface to the upper surface of the rolled product.

[0031] The above-described embodiments of the method according to the invention take into account that the heat flow in the longitudinal or transverse direction in the rolled product is negligible compared to the heat flow in the thickness direction of the rolled product. Therefore, the enthalpy distribution and / or temperature distribution in the rolled product section can be calculated with sufficient accuracy using a one-dimensional heat conduction equation that describes the enthalpy distribution and / or temperature distribution in the rolled product section along the thickness direction of the rolled product. This significantly reduces the computational effort and computational time compared to the case of using a two-dimensional or three-dimensional heat conduction equation. The above-described boundary conditions take into account the main influences on the development of the enthalpy distribution and temperature distribution in the rolled product.

[0032] In a further embodiment of the method according to the invention, the surface temperature of the surface portion of the rolled product surface belonging to the rolled product section is measured at at least one measurement point through which the rolled product section passes before passing through the cooling section, and the original initial enthalpy distribution and / or the original initial temperature distribution for the simulation of the passage of the rolled product section through the cooling section are determined according to the at least one measured surface temperature.

[0033] The method according to the invention can also be carried out separately for the upper surface or the bottom surface of the rolled product, or for the upper surface and the bottom surface of the rolled product.

[0034] The cooling section according to the invention for cooling the rolled product upstream of the finishing train of the hot rolling mill is - one or more cooling devices, the plurality of cooling devices being arranged one behind the other along the cooling path through the cooling section, and each of the plurality of cooling devices being able to supply a coolant flow rate of the coolant onto the rolled product surface of the rolled product, the coolant flow rate being adjustable between a value of zero and a maximum value specific to the cooling device, one or more cooling devices; - a plurality of conveying rollers designed to convey the rolled product along the cooling section path through the cooling section; - a control unit designed to operate the cooling section according to the method according to the invention according to any one of the preceding claims; and comprises.

[0035] In one embodiment of the cooling section according to the present invention, which includes a plurality of cooling devices, the cooling devices are arranged along the cooling section path according to the maximum value of the coolant flow rate they can supply, and the maximum value is monotonically decreasing towards the finishing row. This enables rapid cooling of the rolled product at the start of the cooling section. Furthermore, since the surface temperature of the rolled product generally reaches its minimum value already at the rear part of the cooling section, only a low cooling capacity is required there, so the cooling devices at the rear part of the cooling section can be designed to be simpler and more cost-effective than those at the front part of the cooling section.

[0036] The characteristics, features, and advantages of the present invention described above, as well as the ways in which they are achieved, will be more clearly and distinctly understood in conjunction with the following description of exemplary embodiments, which will be explained in more detail in conjunction with the drawings.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0038] The corresponding parts in the figures are denoted by the same reference numerals.

[0039] FIG. 1 is a diagram schematically showing a hot rolling mill 1. The hot rolling mill 1 includes a heating furnace 3, a roughing train 5, an intermediate roller table 7, a finishing train 9, an exit cooling region 11, and a coiler region 13. A rolled product 15 is conveyed through the hot rolling mill 1 in the direction from the heating furnace 3 to the coiler region 13.

[0040] The heating furnace 3 is arranged upstream of the roughing train 5 and is set to heat the rolled product 15 to a specific temperature, for example, in the range of 1100°C to 1200°C.

[0041] The roughing train 5 has at least one roughing train rolling stand 17. In the roughing train 5, the rolled product 15 is rolled into a transfer bar having a transfer bar thickness in the range of, for example, 30 mm to 170 mm.

[0042] The intermediate roller table 7 conveys the rolled product 15 from the roughing train 5 to the finishing train 9 at a predetermined conveying speed. The intermediate roller table 7 has an exemplary embodiment of a cooling unit 19 according to the present invention. The cooling unit 19 includes a plurality of cooling devices 21, 22, 23 arranged longitudinally along a cooling unit path passing through the cooling unit, a plurality of conveying rollers 25 designed to convey the rolled product 15 along the cooling unit path passing through the cooling unit, and a control unit 27 designed to operate the cooling unit 19 according to an exemplary embodiment of the method according to the present invention for cooling the rolled product 15. An exemplary embodiment of the method according to the present invention will be described below with reference to FIGS. 2 to 6. FIG. 1 shows an example of the cooling unit 19 having three cooling devices 21, 22, 23. However, the cooling unit 19 can also have a different number of cooling devices 21, 22, 23.

[0043] By each of the cooling devices 21, 22, 23, a coolant flow rate of the coolant 35 that can be set between zero and a maximum value specific to the cooling devices 21, 22, 23 can be supplied onto the rolled product surface 29 of the rolled product 15 within the effective regions 31, 32, 33 of the cooling devices 21, 22, 23. The coolant 35 is, for example, water. In FIG. 1, the rolled product surface 29 is the upper surface of the rolled product 15. In other exemplary embodiments, the rolled product surface 29 may be the bottom surface of the rolled product 15, in which case the cooling devices 21, 22, 23 are arranged below the rolled product 15. Further, the cooling section 19 can be provided with the cooling devices 21, 22, 23 on both the upper and lower surfaces of the rolled product 15. In the latter case, the method according to the invention is carried out separately for the upper and lower surfaces of the rolled product 15.

[0044] Each of the cooling devices 21, 22, 23 is designed, for example, as a cooling bar having a plurality of nozzles that extend along the width of the rolled product 15 and can supply the coolant 35 onto the rolled product surface 29. The effective regions 31, 32, 33 are assigned to the cooling devices 21, 22, 23 such that the effective regions 31, 32, 33 of adjacent cooling devices 21, 22, 23 are directly adjacent to each other. For example, the cooling devices 21, 22, 23 are arranged along the cooling path according to the maximum value of the supplyable coolant flow rate, and the maximum value monotonically decreases towards the finishing stand 9.

[0045] The intermediate roller table 7 is also provided with a measuring device 37 at a measuring point 39 upstream of the cooling section 19, and the measuring device 37 is set to detect the surface temperature of the rolled product surface 29. For example, the measuring device 37 is equipped with a pyrometer for this purpose.

[0046] The finishing stand 9 includes a plurality of finishing stand rolling stands 41 and finishing stand cooling devices 43, and each of the finishing stand cooling devices 43 is arranged between two finishing stand rolling stands 41 and can supply each finishing stand coolant 45 onto the rolled product surface 29. In the finishing stand 9, the finishing stand rolling stands 41 are used to reduce the plate thickness of the rolled product 15 to the final plate thickness.

[0047] In the outlet cooling area 11, outlet cooling devices 47, 49 are arranged, and the outlet coolant 51 can be supplied onto the surface 29 of the rolled product by using the outlet cooling devices 47, 49. In the outlet cooling area 11, the rolled product 15 is cooled after the finishing row 9.

[0048] At least one rolled product coiler 53 is arranged in the coiler area 13 and is designed to wind up the rolled product 15.

[0049] FIG. 2 shows a flowchart of a method according to the invention, including method steps 100, 200, 300 for cooling the rolled product 15 in the cooling section 19.

[0050] In a first method step 100, the control unit 27 receives a minimum value T of the surface temperature of the surface 29 of the rolled product during the conveyance of the rolled product 15 through the cooling section 19. min The minimum value T min is specified, for example, by a higher-level control system (not shown) or by an operator of the hot rolling mill 1. The minimum value T min is the surface temperature of the surface 29 of the rolled product that is not exceeded during the conveyance of the rolled product 15 passing through the cooling section 19.

[0051] In a second method step 200, during the passage of the rolled product 15 through the cooling section 19, a set value of the coolant flow rate supplied from the cooling devices 21, 22, 23 onto the surface 29 of the rolled product is assigned to each of the cooling devices 21, 22, 23. An exemplary embodiment of the second method step 200 will be described in more detail below with reference to FIGS. 3 to 6.

[0052] In a third method step 300, during the passage through the cooling section, the coolant flow rate is sent onto the surface 29 of the rolled product by each of the cooling devices 21, 22, 23, and the coolant flow rate is set to the set value assigned to the associated cooling devices 21, 22, 23 for the passage through the cooling section in the second method step 200.

[0053] Method steps 200 and 300 can also be executed several times so that the set values of the cooling devices 21, 22, 23 can be changed during the conveyance of the rolled product 15 through the cooling section 19. This is indicated by the dashed arrow symbol in FIG. 2.

[0054] For example, the rolled product 15 is divided into a plurality of rolled product portions that pass through the effective regions 31, 32, 33 of the cooling devices 21, 22, 23 in sequence, and method steps 200 and 300 are continuously executed for each rolled product portion. In this case, in the second method step 200, the set value of the coolant flow rate supplied to the portion of the rolled product surface 29 belonging to the rolled product portion by the cooling devices 21, 22, 23 is assigned to each cooling device 21, 22, 23 for the passage of the rolled product portion through the cooling section 19.

[0055] In the third method step 300, the coolant flow rate is supplied onto the portion of the rolled product surface 29 belonging to the rolled product portion by each cooling device 21, 22, 23 during the passage of the rolled product portion through the cooling section, and the coolant flow rate is set to the set value assigned to the associated cooling devices 21, 22, 23 for the passage of the rolled product portion through the cooling section in the second method step 200. Preferably, for each cooling device 21, 22, 23, a delay period elapsed until the change in the set value of the cooling device 21, 22, 23 and the coolant flow rate actually supplied by the cooling device 21, 22, 23 changes to the changed set value is considered, and the set value of the cooling device 21, 22, 23 is changed at a time earlier than the time when the rolled product portion enters the effective regions 31, 32, 33 of the cooling devices 21, 22, 23 by the delay period.

[0056] Figure 3 shows a first exemplary embodiment of a second method step 200 having sub-steps 201 to 216 for determining set values of the cooling devices 21, 22, 23 for the passage of the rolled product 15 through the cooling section 19. In this case, the passage through the cooling section is simulated at least once for the rolled product section of the rolled product 15 at the conveyance speed specified therefor. The execution indices i = 1, …, n number the effective areas 31, 32, 33 of the cooling devices 21, 22, 23 in the order in which the rolled product section passes through during the passage through the cooling section, where n represents the number of cooling devices 21, 22, 23 (as already explained above, only three cooling devices 21, 22, 23 are shown as an example in FIG. 1. This method will be explained below for a general number of cooling devices 21, 22, 23).

[0057] In a first sub-step 201, after the passage through the cooling section, i.e., after the passage through all the effective areas 31, 32, 33, the target average temperature

Number

[0058] In a second sub-step 202, the total coolant amount W of the coolant 35 is accepted, and the coolant 35 will be supplied in total at most while the cooling section passes through the surface portion of the rolled product surface 29 belonging to the rolled product section. After the second sub-step 202, a third sub-step 203 is executed.

[0059] In a third sub-step 203, the residual coolant amount W R is substituted as an initial value for the total coolant amount W, and the value 1 is substituted for the execution index i as an initial value. After the third sub-step 203, a fourth sub-step 204 is executed for the execution index value i = 1.

[0060] In a fourth sub-step 204, the initial temperature distribution of the rolled product section along the thickness direction of the rolled product when entering the effective areas 31, 32, 33 with the current value of the execution index i

Number

[0061] When the execution index value i = 1, the original initial temperature distribution is, for example, the initial temperature distribution derived from the surface temperature of the rolled product surface 29 recorded by the measuring device 37 and / or from the heating temperature of the heating furnace 3

Number

Number

[0062] For each execution index value i > 1, the temperature distribution determined in the previous execution of sub-step 207 for the effective regions 31, 32, 33 having the execution index value i - 1

Number

Number

Number

[0063] The initial temperature distribution

Number

Number

[0064] In the fifth sub-step 205, the current value of the execution index i is used to determine the default values of the coolant flow rates of the cooling devices 21, 22, 23

Number

Number

Number

Number

Number

Number

Number

Number

Number

[0065] In other words, the residual coolant amount W R the current value of is the maximum coolant amount

Number

Number

Number

Number

Number

Number

[0066] In the sixth sub-step 206, the set value w i of the coolant flow rate of the cooling devices 21, 22, 23 with the current value of the execution index i is the default value

Number

[0067] In the seventh sub-step 207, using the current value of the execution index i, the temperature distribution of the rolled product portion along the thickness direction of the rolled product when exiting the effective regions 31, 32, 33

Number

Number

Number

[0068] The temperature distribution in the seventh sub-step 207

Number

Number

Number

[0069] The simple form of the heat conduction equation is as follows. [Number] Here, [Number] is the thermal diffusivity of the rolled product 15, λ is the thermal conductivity, [Number] is the density, and c is the specific heat capacity.

[0070] The boundary conditions required for the heat conduction equation (3) are the heat flux density j o on the upper surface (x = 0) and the heat flux density j u on the lower surface (x = d) of the rolled product 15. For example, in the case of the upper surface, [Number] is used, and for the bottom surface, [Number] is used. Here, v is the average transport velocity when passing through the effective region, and hereinafter it is simply called the transport velocity, and ε o is the radiation coefficient of heat radiation from the upper surface, and ε u is the heat radiation coefficient from the bottom surface, which is smaller than ε o due to the reflection of heat radiation at the transport roller 25. f [[ID=5)) L (T o , T e , v) and f ) L (T u , T e , v) are functions that describe the cooling effect of the ambient air depending on the surface temperature T o of the upper surface of the rolled product 15 or the surface temperature T u of the bottom surface of the rolled product 15, and describe the ambient temperature T e and the transport velocity v. f R (T u , T e , v) is the surface temperature T u , the ambient temperature T eand a function f that describes the cooling effect of the conveying roller 25 according to the conveying speed v. w (T o 、v、T w 、w oi ) is a function that explains the cooling effect of the upper surface cooling devices 21, 22, 23, that is, the cooling devices 21, 22, 23 that cool the upper surface of the rolled product 15, and the surface temperature T o 、conveying speed v, coolant temperature T w 、and the set value w oi has an execution index value i that depends on the coolant flow rate of the cooling devices 21, 22, 23 given by. Therefore, f w (T u 、v、T w 、w ui ) is a function that describes the cooling effect of the bottom side cooling devices 21, 22, 23, and the surface temperature T u 、conveying speed v, coolant temperature T w 、and the set value w ui has an execution index value i that depends on the coolant flow rate of the cooling devices 21, 22, 23 given by.

[0071] The function f w is often separated to enable simpler parameterization. For example, to make it easier to explain the dependency of the cooling effect f T (T, v) on the conveying speed v and the related surface temperature T = T o or T = T u using the execution index value i, the dependency of the cooling effect g T (T w ) on the coolant temperature T w and the dependency of the cooling effect h w (w) of the upper side or bottom side cooling devices 21, 22, 23 on the coolant flow rate w = w oi or w = w ui are included, f w (T, v, T w 、w) = f T (T, v) g T (T w ) h w (w) (4c) It becomes as follows. At the points along the cooling path where the coolant flow rate is not supplied onto the rolled product 15 from the upper cooling devices 21, 22, 23, the following equation: f w (T o , v, T w , w oi ) = 0 is applied. Accordingly, at the points along the cooling section path where the coolant flow rate is not supplied onto the rolled product 15 from the bottom cooling devices 21, 22, 23, f w (T u , v, T w , w oi ) = 0 is applied.

[0072] When the method according to the present invention is executed for the upper and lower cooling devices 21, 22, 23, it is executed separately for the upper cooling devices 21, 22, 23 and the lower cooling devices 21, 22, 23. Therefore, in FIG. 3, the following: wi = w oi is applied to the upper cooling devices 21, 22, 23, and for the lower cooling devices 21, 22, 23, accordingly, w i = w ui etc. are applied. Here, the execution range of the execution index i of the upper cooling devices 21, 22, 23 may be different from the execution range of the execution index i of the lower cooling devices 21, 22, 23.

[0073] Another form of the heat conduction equation is as follows.

Equation

Equation

[0074] The phase fractions can be calculated here if necessary, especially in combination with the solution of the heat conduction equation. For example, a system of coupled differential equations can be used for the phase components.

Number

[0075] Equation (3), as well as equations (5) and (6), using the current value of the execution index i, gives the temperature distribution

Number

Number

Number

Number

Number

[0076] The functions f L , f w , f R are appropriately parameterized by methods known from the prior art, such as, for example, the so-called B-spline. In some cases, a closed representation can also be specified. In this regard, see, for example, Non-Patent Document 1. Here, in Eq. (6), the heat flow constant

Number

[0077] After the seventh sub-step 207, the eighth sub-step 208 is executed.

[0078] In the eighth sub-step 208, the temperature

Number

Number

Number

[0079] Therefore, when the calculated surface temperature of the rolled product surface 29 when exiting the effective regions 31, 32, 33 with the current value of the execution index i is lower than the minimum value T min that is, when the current set value w i for this value of the execution index i is too high, the ninth sub-step 209 is always executed. In the ninth sub-step 209, therefore, to this set value w i a new set value w i is assigned a new (smaller) value, for example using Newton's method, such that the calculated surface temperature for it is approximated to the minimum value T min . Next, the seventh sub-step 207 and the eighth sub-step 208 are executed again. That is, the surface temperature when exiting the effective regions 31, 32, 33 with the current value of the execution index i is calculated for the new set value w i . This is repeated until the calculated surface temperature coincides with the minimum value T min , slightly exceeds the minimum value T min , or slightly exceeds it, for example up to a maximum of 10 °C, preferably up to a maximum of 5 °C. Next, the tenth sub-step 210 is executed.

[0080] In the tenth sub-step 210, the value of the residual coolant amount W R is changed from the previous value by subtracting the coolant amount W i corresponding to the set value w i sent to the surface portion of the rolled product surface 29 belonging to the rolled product section by the cooling devices 21, 22, 23 together with the current value of the execution index i. The coolant amount W i can be calculated, for example

Number

[0081] After the 10th sub-step 210, the 11th sub-step 211 is executed.

[0082] In the 11th sub-step 211, it is checked whether the current value of the execution index i has reached the final value n, that is, whether the cooling part passage by simulation has ended. If not, the 12th sub-step 212 is executed. If not, the 13th sub-step 213 is executed.

[0083] In the 12th sub-step 212, the value of the execution index i is incremented. Next, the 4th sub-step 204 is executed for the new value of the execution index i.

[0084] In the 13th sub-step 213, after the passage of the cooling part by simulation, that is, after the passage of all the effective regions 31, 32, 33 by simulation, the average temperature of the rolled product part is calculated. This average temperature is, for example, the temperature distribution calculated in the previous execution of the 7th sub-step 207

Number

Number

[0085] In the 14th sub-step 214, the average temperature calculated in the previous execution of the 13th sub-step 213

Number

Number

Number

Number

[0086] Therefore, if the calculated average temperature after passing through the cooling section by simulation

Number

Number

Number

Number

Number

Number

Number

Number

Number

Number

[0087] After the 15th sub-step 215, the 3rd sub-step 203 is executed using the new value of the total coolant amount W. That is, a further simulation of the cooling section passage of the rolled product section is started by changing the value of the total coolant amount W. The simulation of the cooling section passage continues until the calculated average temperature

Number

Number

Number

[0088] Calculated average temperature after passing through the cooling section by simulation

Number

Number

[0089] When the value of the total coolant amount W becomes zero, each set value w i , i = 1, …, n is assigned the value 0. That is, ∀i: w i = 0 is used, and then the 16th sub-step 216 is executed. When the value of the total coolant amount W reaches or exceeds the maximum value W max each set value w i is assigned the maximum value

Number

Number

[0090] In the 16th sub-step 216, the second method step 200 ends, and the last coolant flow rate setting value w of the coolant flow rate determined in the method step 200 i is stored for each of the cooling devices 21, 22, 23. The coolant flow rates of the associated cooling devices 21, 22, 23 are set to this setting value w i in the third method step 300.

[0091] FIG. 4 shows a second exemplary embodiment of the method step 200. This exemplary embodiment differs from the first exemplary embodiment described with reference to FIG. 3 only in the modification of the sub-step 206 and the omission of the sub-steps 208 and 209. Therefore, below, only the differences from the first exemplary embodiment described with reference to FIG. 3 will be described and commented on.

[0092] In the sub-step 206 of this exemplary embodiment, during the passage of the cooling section by simulation of the rolled product section, the setting value w of the coolant flow rate of the cooling devices 21, 22, 23 according to the current value of the execution index i i is

Number

[0093] In Equation (9),

Number

Number

Number

Number

Number

[0094] f i (T) is 0 when T ≦ T min and 1 when

Number

Number

Number

Number

[0095] T min is the minimum value allowed in the first method step 100 for the surface temperature of the rolled product surface 29 during the conveyance of the rolled product 15 through the cooling section 19.

Number

Number

Number

Number

Number

[0096] A second exemplary embodiment of method step 200 shown in FIG. 4 is simpler than the first exemplary embodiment shown in FIG. 3 because sub-steps 208 and 209, and thus the potential repetition of sub-steps 207 to 209, are omitted. In particular, the second exemplary embodiment of method step 200 generally requires less computational effort than the first exemplary embodiment, and thus generally also requires less computing time or lower computing power. In contrast, the first exemplary embodiment of method step 200 can more accurately match the set values of the coolant flow rates of the cooling devices 21, 22, 23 to the minimum value T min by repeating sub-steps 207 to 209, thus generally enabling faster cooling of the rolled product 15 than the second exemplary embodiment.

[0097] It has already been explained that one embodiment of the method according to the invention provides method steps 200 and 300 which are continuously executed on the rolled product portion of the rolled product 15 passing continuously through the effective regions 31, 32, 33 of the cooling devices 21, 22, 23. In this embodiment of the method according to the invention, method step 200 is carried out for each rolled product portion, for example, according to one of the exemplary embodiments described with reference to FIG. 3 or FIG. 4. However, instead, it is also possible to modify the exemplary embodiments described with reference to FIGS. 3 and 4 for this embodiment of the method according to the invention.

[0098] FIG. 5 shows such a modification of the exemplary embodiment shown in FIG. 3. In this change, a second execution index j for numbering the rolled product portions is used. In the second sub-step 202, an initial total coolant amount W of the coolant 35 is received as in the exemplary embodiment shown in FIG. 3. Further, in the second sub-step 202, a value 1 is assigned to the second execution index j as an initial value. Sub-steps 203 to 214 are carried out for the relevant current value of the second execution index j, that is, for the relevant rolled product portion, in the same manner as sub-steps 203 to 214 of the exemplary embodiment shown in FIG. 3.

[0099] The average temperature calculated in sub-step 213

Number

Number

Number

Number

Number

[0100] After sub-step 217, sub-step 203 is executed for the new value of the second execution index j. That is, the simulation of the subsequent rolled product part passing through the cooling section is started using the total coolant amount W that may have been changed. In the exemplary embodiment shown in FIG. 5, therefore, the passing through the cooling section is simulated only once for each rolled product part, and the total coolant amount W that is probably adapted in sub-step 215 is transferred to the simulation of the subsequent rolled product part passing through the cooling section. In this way, the second method step 200 executed for a rolled product part is linked to the second method step 200 executed for a subsequent rolled product part. After each execution of the second method step 200, for each cooling device 21, 22, 23, the set value w of the coolant flow rate determined in this embodiment of the method step 200i is stored as the associated value of the second execution index j. The set value w stored for the value of the second execution index j i is not overwritten by the set value w determined for another value of the second execution index j i .

[0101] The repeated execution of the second method step 200 ends when the second execution index j reaches the final value. For example, each time the second method step 200 is executed, it is checked whether the second execution index j has reached the final value, and the sub-step 217 is executed only if not. Otherwise, the repeated execution of the second method step 200 is terminated. For clarity, this is not shown in FIG. 5.

[0102] Furthermore, in FIG. 5, strictly speaking, variables with index i or n need to have an additional index j if these variables may be different from each other when the value of the second execution index j is different. For example, the set value is w i instead of w ij and needs to be referred to. This is also omitted in FIG. 5 for clarity.

[0103] The third method step 300 can also be executed separately for each rolled product section and independently of the other rolled product sections. For one value k of the second execution index, the third method step 300 can already be executed, where, during the passage of the rolled product section having the value k of the second execution index through the cooling section, the coolant flow rate w determined for this value k by the cooling devices 21, 22, 23 iis supplied onto the rolled product section, while a second method step 200 is carried out for a value j of a second execution index with j > k. For this purpose, in method step 300, when the rolled product section having the value k enters the effective regions 31, 32, 33 of the cooling devices 21, 22, 23, it is determined for each cooling device 21, 22, 23 as a function of the conveying speed or the time course of the conveying speed. Taking into account the associated delay times, the cooling devices 21, 22, 23 then supply exactly the coolant flow rate w determined for this value k when the rolled product section having the value k is located in the effective regions 31, 32, 33 of the cooling devices 21, 22, 23 i is set to be supplied.

[0104] FIG. 6 shows a modification similar to FIG. 5 of an exemplary embodiment of the second method step 200 shown in FIG. 4.

[0105] The exemplary embodiment of the method according to the invention described above can also be carried out when the rolled product is conveyed a plurality of times through the cooling section 19. For example, the finishing train 9 can comprise reversing stands in which the rolled product 15 is guided a plurality of times in alternating directions. The rolled product 15 can then also be conveyed a plurality of times in alternating directions through the cooling section 19. In this case, method steps 200 and 300 are carried out for each passage through the cooling section. In this case, for example, a second measuring point is provided downstream of the cooling section 19, that is to say between the intermediate roller table 7 and the finishing train 9, at which the surface temperature of the surface portion of the rolled product surface 29 belonging to the rolled product section is recorded before the rolled product section passes through the cooling section 19 from the second measuring point. In the simulation of the passage of the rolled product section through the cooling section, the original initial enthalpy distribution and / or the original initial temperature distribution are determined as a function of the surface temperature of the surface portion of the rolled product surface 29 belonging to the rolled product section detected at the second measuring point.

[0106] Furthermore, the intermediate roller table 7 can have a plurality of cooling sections 19, or the cooling section 19 can have a plurality of partial cooling sections, and the method according to the invention can be carried out separately for each of them (wherein each partial cooling section is understood as a cooling section in the meaning of the invention). For example, if an intermediate measuring point where the surface temperature of the rolled product 15 is recorded is arranged on the intermediate roller table 7, the method according to the invention can be carried out individually for the first partial cooling section or the cooling section arranged between the first measuring point 39 and the intermediate measuring point, and for the second partial cooling section or the cooling section arranged between the intermediate measuring point and the finishing row 9. Next, the original initial temperature distribution and / or the original initial enthalpy distribution of the second partial cooling section or the second cooling section are determined according to the surface temperature of the rolled product 15 recorded at the intermediate measuring point. The same applies when a plurality of intermediate measuring points are arranged on the intermediate roller table 7 and the surface temperature of the rolled product 15 is recorded at each intermediate measuring point.

[0107] FIG. 7 shows the temperature T K 、T S and

No.

No.

[0108] The rolled product section enters the cooling section 19 at about 3 seconds after the time zero point. Due to the cooling effect of the cooling devices 21, 22, 23 at the head of the cooling section 19, the surface temperature T S is from about 1070 °C when the rolled product section enters the cooling section 19 to about 800 °C in this case, and the surface temperature T is already at about 5.5 seconds after the time zero point.S The minimum value T reached min rapidly decreases until. During further passage of the rolled product section through the cooling section, the surface temperature T of the latter S is maintained relatively constant at the minimum value T by the cooling devices 21, 22, 23 of the cooling section 19 according to the present invention from the time zero point until the rolled product section exits the cooling section 19 approximately 7.7 seconds later min . Thereafter, since heat is conducted from the inside of the rolled product section to the surface 29 of the rolled product, the surface temperature T rises again due to insufficient cooling S . The central temperature T of the rolled product section K is maintained relatively constant at approximately 1100 °C during passage through the cooling section. The average temperature of the rolled product section

Number

[0109] Although the present invention has been illustrated and described in detail by preferred exemplary embodiments, the present invention is not limited by the disclosed examples, and those skilled in the art will be able to derive other variations without departing from the scope of protection of the present invention

Explanation of reference numerals

[0110] 1 Hot rolling mill 3 Heating furnace 5 Roughing train 7 Intermediate roller table 9 Finishing train 11 Exit cooling area 13 Coiler area 15 Rolled product 17 Roughing train rolling stand 19 Cooling section 21, 22, 23 Cooling devices 25 Conveyor roller 27 Control unit 29 Rolled product surface 31, 32, 33 Effective area 35 Coolant 37 Measuring device 39 Measuring point 41 Finishing train rolling stand 43 Finishing train cooling device 45 Finishing train coolant 47, 49 Exit cooling device 51 Exit coolant 53 Rolled product coiler 100, 200, 300 Method steps 201 - 217 Sub - steps t Time T K Central temperature T S Surface temperature

Number

Claims

1. A method for cooling a rolled product (15) in a cooling section (19), wherein the cooling section (19) is arranged upstream of the finishing train (9) of a hot rolling mill (1), and the rolled product (15) passes through the cooling section (19) once along a cooling section path at a predetermined conveying speed or several times in alternating directions at a predetermined conveying speed each time. The cooling section (19) has one cooling device (21, 22, 23) having effective regions (31, 32, 33), or a plurality of cooling devices (21, 22, 23) arranged one after another along the cooling section path, each having effective regions (31, 32, 33), and the effective regions (31, 32, 33) of adjacent cooling devices (21, 22, 23) are directly adjacent to each other. By each cooling device (21, 22, 23) in each effective region (31, 32, 33), the coolant flow rate of the coolant (35) can be supplied onto the surface (29) of the rolled product of the rolled product (15), and the coolant flow rate can be set between a value of zero and a maximum value specific to the cooling device (21, 22, 23). - During the conveyance of the rolled product (15) through the cooling section (19), the minimum value of the surface temperature (T Ｓ ) of the rolled product surface (29) is accepted, - In order to maintain the minimum value, for each passage of the cooling section (19), a set value of the coolant flow rate is assigned to each cooling device (21, 22, 23). - The coolant flow rate is sent onto the surface (29) of the rolled product by each cooling device (21, 22, 23) for each passage of the cooling section, and the coolant flow rate is set to the set value assigned to the relevant cooling device (21, 22, 23) of the passage of the cooling section. - In order to determine the set value for the passage of the cooling section, at least one simulation is performed on the rolled product section of the rolled product (15) passing through the cooling section (19) at the predetermined conveying speed. For each passage of the cooling section by simulation, the following values are continuously determined for each cooling device (21, 22, 23), that is, - - The default value of the coolant flow rate supplied by the cooling device (21, 22, 23) is received or determined at the latest immediately before the rolled product section enters the effective region (31, 32, 33) of the cooling device (21, 22, 23). - - Based on the initial enthalpy distribution and / or initial temperature distribution in the rolled product section when entering the effective regions (31, 32, 33) of the cooling devices (21, 22, 23), using a physical model, calculate the enthalpy distribution and / or temperature distribution in the rolled product section when exiting the effective regions (31, 32, 33) of the cooling devices (21, 22, 23), - - The set value does not exceed the default value, and the surface temperature of the rolled product surface (29) derived from the initial enthalpy distribution and / or initial temperature distribution, or the surface temperature of the rolled product surface (29) derived from the calculated enthalpy distribution and / or calculated temperature distribution of the rolled product section does not fall below the minimum value when exiting the effective regions (31, 32, 33) of the cooling devices (21, 22, 23). The coolant flow rate supplied from the cooling devices (21, 22, 23) to the rolled product surface (29) is determined to be quasi-maximized under these secondary conditions, - - For each pair of two effective regions (31, 32, 33) that the rolled product section continuously passes through immediately after passing through the cooling section, the calculated enthalpy distribution and / or calculated temperature distribution for the first effective region (31, 32, 33) that has passed through is assigned to the other effective region (31, 32, 33) as the initial enthalpy distribution and / or initial temperature distribution when entering the other effective region (31, 32, 33), - - The original initial enthalpy distribution and / or original initial temperature distribution is accepted for the first cooling device (21, 22, 23) through which the rolled product section passes during passage through the cooling section, Method.

2. For each passage of the rolled product section through the cooling section by simulation, to at least one cooling device (21, 22, 23), 【Number 1】 The set value is assigned according to, 【Number 2】 Is the default value of the coolant flow rate supplied by the cooling device (21, 22, 23), 【Mathematics 3】 is the surface temperature of the surface (29) of the rolled product, derived from the initial enthalpy distribution and / or the initial temperature distribution when entering the effective region (31, 32, 33) of the cooling devices (21, 22, 23), T ｍｉｎ is the surface temperature (T Ｓ ) of the surface of the rolled product, which is the minimum value of 【Number 4】 is a preliminary temperature difference that can be determined in advance, and f ｉ (T) is 0 when T ≤ T ｍｉｎ and 【Number 5】 In the case of 1, interval 【Number 6】 Is a strictly monotonically increasing function in. The method according to claim 1.

3. First, calculate the surface temperature of the rolled product surface (29) when exiting the effective region (31, 32, 33) of the cooling devices (21, 22, 23) with respect to the default value of the coolant flow rate of the cooling devices (21, 22, 23). When the surface temperature calculated with respect to the default value does not fall below the minimum value, set the set value equal to the default value, whereby the set value of at least one cooling device (21, 22, 23) is determined for each pass through the cooling section by simulation. When the surface temperature calculated with respect to the default value falls below the minimum value, in order to determine the set value of the coolant flow rate at which the calculated surface temperature when exiting the effective region (31, 32, 33) coincides with the minimum value, the calculation of the surface temperature when exiting the effective region (31, 32, 33) is repeated for at least one coolant flow rate smaller than the default value. The method according to claim 1.

4. For each cooling device (21, 22, 23), the maximum value of the coolant flow rate specific to the associated cooling device (21, 22, 23) is accepted as the default value of the coolant flow rate for each pass through the cooling section by simulation. The method according to claim 1.

5. For the simulation of the pass through the cooling section of the rolled product section, the total coolant amount of the coolant (35) supplied in total to the surface portion of the rolled product surface (29) belonging to the rolled product section during the pass through the cooling section is determined, and the default value of the coolant flow rate for the pass through the cooling section by simulation is determined according to the total coolant amount specified for the pass through the cooling section and the conveying speed. The method according to claim 1.

6. The target average temperature of the rolled product (15) is received after passing through the cooling section. In each simulation of the pass through the cooling section of the rolled product section, the average temperature of the rolled product section at the end of the pass through the cooling section is calculated. When the calculated average temperature does not correspond to the target average temperature, the total amount of coolant is changed for subsequent simulations of the pass through the cooling section of the rolled product section in order to make the calculated average temperature coincide with the target average temperature. The method according to claim 5.

7. During the simulation of the passage of the rolling product section through the cooling section, a residual coolant amount is assigned to each cooling device (21, 22, 23), and the total coolant amount is assigned as the residual coolant amount to the first cooling device (21, 22, 23) through which the cooling section passes. For each further cooling device (21, 22, 23), as the residual coolant amount, the amount of coolant supplied by the preceding cooling device (21, 22, 23) according to the coolant flow rate set value determined for the surface portion of the rolling product surface (29) belonging to the rolling product section with respect to the preceding cooling device (21, 22, 23) is subtracted from the residual coolant amount of the preceding cooling device (21, 22, 23). The default value of the coolant flow rate of the cooling device (21, 22, 23) is 【Number 7】 calculated according to 【Number 8】 is the maximum value of the coolant flow rate of the cooling devices (21, 22, 23), and is W Ｒ is the remaining coolant amount assigned to the cooling devices (21, 22, 23), 【Number 9】 the maximum amount of coolant that can be supplied onto the surface portion of the rolling product surface (29) belonging to the rolling product section by the cooling device (21, 22, 23) during the passage through the cooling section. The method according to claim 5.

8. During the simulation of the passage of the rolling product section through the cooling section, if a set value smaller than the default value received for the cooling device (21, 22, 23) is determined for the cooling device (21, 22, 23), and if there is at least one subsequent cooling device (21, 22, 23) that is reached later during the passage through the cooling section and the received default value is smaller than the maximum value of the coolant flow rate of the cooling device (21, 22, 23), in order to adapt the total amount of coolant supplied onto the surface portion of the rolling product surface (29) belonging to the rolling product section during the passage through the cooling section to the total amount of coolant determined for the passage through the cooling section, the default value of at least one of the subsequent cooling devices (21, 22, 23) is increased. The method according to claim 5.

9. During the simulation of the passage of the rolling product section through the cooling section, in order to calculate the enthalpy distribution and / or temperature distribution of the rolling product section when exiting from the effective regions (31, 32, 33) of the cooling device (21, 22, 23), a one-dimensional heat conduction equation describing the enthalpy distribution and / or temperature distribution of the rolling product section along the thickness direction of the rolling product is solved. The method according to claim 1.

10. In order to solve the one-dimensional heat conduction equation, boundary conditions are considered which parameterize the cooling of the rolled product section by thermal radiation, the coolant supplied to the surface (29) of the rolled product, the heat dissipated from the rolled product section to the ambient air, and the heat dissipated from the rolled product section to the conveying rollers (15) that convey the rolled product (15). The method according to claim 9.

11. The surface temperature (T Ｓ ) of the surface portion of the surface (29) of the rolled product belonging to the rolled product section is measured at at least one measurement point (39) through which the rolled product section passes before passing through the cooling section, and the original initial enthalpy distribution and / or the original initial temperature distribution for the simulation of the passage of the rolled product section through the cooling section are determined according to at least one measured surface temperature (T Ｓ ), the method according to claim 1.

12. The method according to claim 1, which is carried out separately for the upper surface (29) or the lower surface (29) of the rolled product (15), or for the upper surface (29) and the lower surface (29) of the rolled product.

13. A cooling section (19) for cooling the rolled product (15) upstream of the finishing train (9) of the hot rolling mill (1), the cooling section (19) comprising - One cooling device (21, 22, 23) or a plurality of cooling devices (21, 22, 23), the plurality of cooling devices (21, 22, 23) being arranged one after another along the cooling path passing through the cooling section (19), and each of the plurality of cooling devices (21, 22, 23) being capable of supplying a coolant flow rate of the coolant (35) onto the surface (29) of the rolled product (15), the coolant flow rate being settable between a value of zero and a maximum value specific to the cooling device (21, 22, 23), one cooling device (21, 22, 23) or a plurality of cooling devices (21, 22, 23); and - A plurality of conveying rollers (25) designed to convey the rolled product (15) along the cooling section path passing through the cooling section (19); and - A control unit (27) designed to operate the cooling section (19) according to the method according to any one of claims 1 to 12. The cooling section (19) comprising the above.

14. The cooling section (19) according to claim 13, comprising a plurality of cooling devices (21, 22, 23), the plurality of cooling devices (21, 22, 23) being arranged along the cooling section path according to the maximum value of the coolant flow rate that can be supplied by the plurality of cooling devices (21, 22, 23), the maximum value being monotonically decreasing towards the finishing train (9).

Images