JP2013123732A - Hot finish rolling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide technology capable of controlling temperature of a plate after finish rolling to be target temperature at the outlet side of finishing roll with good accuracy without reducing finish rolling speed more than necessary.SOLUTION: A hot finish rolling method controls plate temperature at a finish rolling machine outlet side to be the target temperature at the outlet side of finishing roll by cooling a plate with a cooling device while carrying out finish rolling with a finish rolling speed pattern which is preliminarily set along the longitudinal direction of the hot-rolled metal plate. A target cooling amount that makes plate temperature at a finish rolling machine outlet side to be the target temperature at the outlet side of finishing roll is obtained from plate temperature at a finish rolling machine inlet side per cut plate made by virtually dividing the plate along the longitudinal direction. Whether or not the target cooling amount exceeds a maximum cooling amount output by a cooling device is determined, finish rolling speed of a cut plate part determined that the target cooling amount exceeds the maximum cooling amount is set and changed to finish rolling speed less than a set finish rolling speed set by the finish rolling speed pattern.

Description

  The present invention relates to a hot finish rolling technique characterized by cooling control in hot finish rolling of a hot rolled metal sheet such as a hot rolled steel sheet.

In general, in the hot rolling steel finishing rolling equipment, operation is performed with the goal of high-efficiency operation within a range that satisfies the quality. For this reason, if it can operate by setting the finishing rolling speed to the limit of the equipment within the range where the quality can be satisfied, it leads to a great merit in terms of efficiency improvement.
Here, in the hot finish side temperature control, which is one of the controls during finish rolling to satisfy the quality, the slab is heated in a heating furnace and rolled with a roughing mill to form a rough bar. A plate portion for every 1 m (each cut plate) in the bar is set as a control target, and a discharge pattern (target cooling amount) is calculated for each control target (for every 1 m of coarse bar, that is, every cut plate). And by controlling the discharge and stop of each cooling water of the cooling device with the discharge pattern calculated for each cut plate, the temperature of the plate after finish rolling is controlled to be the finish target temperature. Here, the cooling amount is usually the finish rolling speed, the actual temperature on the entry side, the finish target temperature on the entry side (the reference temperature on the entry side obtained by converting the finish side target temperature to the temperature on the entry side). Calculated from

  For example, in the technique described in Patent Document 1, the preset finishing rolling speed is within the range where it is estimated that the finishing target temperature can be satisfied from the past results, and the performance of the rolling equipment such as a rolling mill is used. Was set up. That is, in the conventional hot finish delivery side temperature control, cooling control is performed on the premise that the product is operated at a finish rolling speed that satisfies the quality. Patent Document 2 describes a method of increasing the finishing rolling speed when the actual temperature is lower than the finishing delivery target temperature.

JP 2007-210009 A JP 2009-95852 A

However, since the maximum finishing speed that is estimated to satisfy the finishing delivery target temperature from the past results is mechanically set, there is a risk that the finishing maximum speed may be set lower. There was a possibility that it could not be rolled.
The present invention takes the above-mentioned points into consideration, and provides a technique capable of controlling the temperature of the plate after finish rolling to the finish target temperature more accurately without reducing the finish rolling speed more than necessary. The purpose is to do.

In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention is characterized in that the plate is cooled by a cooling device while performing finish rolling at a preset finish rolling speed pattern along the longitudinal direction of the hot-rolled metal plate. In the hot finish rolling method for controlling the plate temperature on the exit side of the finishing mill to the finish target temperature,
For each cut plate obtained by virtually dividing the plate along the longitudinal direction, from the plate temperature on the finishing mill entry side, the target cooling amount for setting the plate temperature on the exit side of the finishing mill as the finishing target temperature is set to Seeking
It is determined whether the target cooling amount exceeds the maximum cooling amount that can be output by the cooling device, and the finish rolling speed of the cut plate portion that is determined that the target cooling amount exceeds the maximum cooling amount is represented by the finish rolling speed pattern. The setting is changed to a finishing rolling speed lower than the set finishing rolling speed.

Next, in the invention described in claim 2, the maximum finish rolling speed of the finish rolling speed pattern is the maximum finish rolling speed that can be rolled by a finish rolling mill or the maximum thereof. The finishing rolling speed is set to be lower than the finishing rolling speed by a margin speed set in advance.
Next, in the invention described in claim 3, in the configuration described in claim 1 or claim 2, whether or not the target cooling amount exceeds the maximum cooling amount is determined as a target hot rolled metal. It is carried out before the finish rolling of the plate is performed.

Next, when the invention described in claim 4 determines that the target cooling amount exceeds the maximum cooling amount with respect to the configuration described in any one of claims 1 to 3, the maximum cooling amount is determined. The upper limit finish rolling, which is the upper limit of the finish rolling speed that can make the plate temperature on the exit side of the finish mill the finish side target temperature when the cut plate portion determined to exceed the maximum cooling amount is cooled. Calculate the speed,
The maximum finish rolling speed of the preset finish rolling speed pattern is changed to the upper limit finishing rolling speed or less, and the finish rolling speed pattern of the target plate is reset.
Next, the invention described in claim 5 is characterized in that, when the finish rolling speed pattern is reset with respect to the invention described in claim 4, the target cooling amount is recalculated. .

  According to the present invention, it is possible to more accurately control the temperature of the plate after finish rolling to the finish side target temperature without reducing the finish rolling speed more than necessary.

It is a schematic diagram of the finishing rolling mill and its control part concerning an embodiment based on the present invention. It is a figure which shows the structure of the cooling control controller which concerns on embodiment based on this invention. It is a figure explaining the process of the target cooling amount calculating part which concerns on embodiment based on this invention. It is a figure explaining the state before applying this invention, (a) is a figure explaining the temperature and target cooling temperature of a cut plate unit, (b) explains the finishing rolling speed pattern before setting change. It is a figure to do. It is a figure explaining the state at the time of applying embodiment based on this invention, (a) is a figure which shows the finishing rolling speed pattern after a setting change, (b) is the temperature and target cooling temperature of a plate unit. It is a figure explaining. It is a figure which shows the other finish rolling speed pattern after a setting change.

Next, embodiments of the present invention will be described with reference to the drawings.
"Constitution"
(Equipment configuration)
As shown in FIG. 1, the finish rolling mill 1 of the present embodiment includes seven stands F <b> 1 to F <b> 7, and a cooling device 2 is disposed between the stands F <b> 1 to F <b> 7. The cooling device 2 is composed of a cooling water spray device, for example, and can spray cooling water toward the surface of the hot-rolled metal plate 6. In addition, air cooling will be performed in the location which does not spray cooling water. In the present embodiment, as an example of the arrangement of the cooling device 2, as shown in FIG. 1, one of the seven stands F1 to F7 is located in front of the F5, F6, and F7 stands (2e, 2f, and 2g in FIG. 1). , F1 and F4 stand (2a and 2d in FIG. 1), F2 and F3 stand (3b and 2c in FIG. 1), a total of 13 cooling devices are illustrated. In FIG. 1, only the cooling device existing above the plate 6 is illustrated, but actually, the cooling device is similarly disposed below the plate 6, and the plate 6 is viewed from both above and below the plate 6. The cooling can be performed.

An entry side thermometer 3 is installed on the entry side of the finish rolling mill 1 and an exit side thermometer 4 is installed on the exit side of the finish rolling mill 1. It is used to measure the actual temperature on the entry and exit sides.
In addition, on the upstream side of the finish rolling mill 1, a rough rolling mill for rolling the heated slab is disposed, and between the exit side of the rough rolling mill and the entrance side of the finish rolling mill 1, A bar heater BH and an edge heater EH for compensating a temperature drop or the like of the plate 6 are arranged, and the temperature of the plate is compensated from rough rolling to finish rolling. In FIG. 1, symbol R5 illustrates the final stand of the rough rolling mill. Moreover, the 2nd thermometer 5 is arrange | positioned at the delivery side of a rough rolling mill, and it can measure the temperature of the board 6 which is rough-rolled and conveyed to the finishing mill 1.
Further, a pinch roll (not shown) and a winder (not shown) for changing the direction of the plate 6 are arranged on the downstream side of the finish rolling mill 1, and the finish-rolled plate 6 is sequentially wound up by the winder. It is configured to wind up with.

(Rolling control)
The finish rolling control controller 11 controls the reduction amount in each stand F1 to F7 to each target reduction amount corresponding to the plate thickness on the finishing mill entry side, the target plate thickness on the delivery side of the rolling mill, and the finish rolling speed.
The finish rolling speed pattern used as a reference for transporting the plate 6 at the time of finish rolling is preset to a speed pattern that can be rolled at high efficiency based on the specifications of the rolling equipment for each plate. .
Specifically, the finish rolling speed pattern in this embodiment is set as shown in FIG. That is, the finish rolling speed is gradually increased at the first acceleration until a stable tension is generated between the winder and the finishing mill 1 when the tip of the plate 6 after finish rolling is wound around the winding machine. When the winding machine starts winding, the finishing rolling speed is increased at a second acceleration larger than the first acceleration, and the maximum finishing rolling speed (the maximum finishing speed) determined by the specifications of the rolling mill. (Also called speed). Thereafter, rolling is performed at the maximum finish rolling speed until the transition to the tail end side rolling of the plate 6, but when it reaches the tail end side of the plate 6, the finish rolling speed is gradually reduced at the first deceleration. The finish rolling speed pattern shown in FIG. 4 is an example. However, based on such an idea, various finish rolling speed patterns are preset for each piece of equipment.
In the finish rolling control, the reduction control is performed on the cut plate units obtained by virtually dividing the plate 6 into predetermined units along the longitudinal direction.

(Control section for hot finish delivery temperature control)
Next, temperature control (cooling control) during finish rolling will be described. This temperature control is a temperature control in which cooling is performed using the cooling device 2 during finish rolling so that the plate temperature on the exit side of the finish rolling mill becomes the finish target temperature. This temperature control is performed for each cut plate unit in which the plate 6 is virtually divided into predetermined units along the longitudinal direction. This hot finish delivery side temperature control is performed by the cooling controller 10.
As shown in FIG. 1, the cooling controller 10 functionally includes a cooling amount setting adjustment unit 10A and a cooling control unit body 10B.

As shown in FIG. 2, the cooling amount setting adjustment unit 10A includes a temperature tracking unit 10Aa and a spray cooling control unit 10Ab.
The temperature tracking unit 10Aa tracks the position of the cut plate in the finish rolling mill 1 for each cut plate. For example, each cut plate position is estimated by the finish rolling speed. The temperature tracking unit 10Aa outputs tracking information to the spray cooling control unit 10Ab.
Spray cooling control unit 10Ab, based on the target amount of cooling per Setsuban the cooling control unit main body 10B has output C ^*, each switching plate, the cooling water of the cooling apparatus for a target amount of cooling C ^* ejection pattern To decide. Then, referring to the tracking information of each cut plate from the temperature tracking unit 10Aa, the discharge of each cooling device 2 is controlled to adjust the cooling amount to each cut plate to the target cooling amount C *. .

The cooling control unit main body 10B is a control unit that calculates a target cooling amount C ^* for each cut plate with respect to the target plate 6. As shown in FIG. 2, the cooling control unit main body 10B includes a target cooling amount calculation unit 10Ba and a target cooling amount resetting unit 10Bb.
The target cooling amount calculation unit 10Ba changes the setting of the finish rolling speed pattern for the target plate 6 as necessary, and calculates the target cooling amount C ^* for each cut plate.
The target cooling amount resetting unit 10Bb performs a resetting process of the target cooling amount C ^* for the cut plate whose set finishing rolling speed has been changed.

Next, the processing of the target cooling amount calculation unit 10Ba will be described with reference to the flowchart of FIG. Note that the cutting plate at the tip of the target plate 6 is set to n = 1, and the value of the cutting plate n is set to be larger toward the tail end side. The number of cut plates is predetermined for each plate. The processing of the target cooling amount calculation unit 10Ba of the present embodiment is executed when the plate 6 targeted for the position of the second thermometer 5 (rough rolling mill outlet side position) passes.
First, in step S10, the target cooling amount calculation unit 10Ba initializes the cut plate number n, and proceeds to step S20.

In step S20, the finish rolling speed of the target cut plate is acquired based on the finish rolling speed pattern preset for the target plate 6. In step S20, the amount of temperature drop in the case where there is no cooling by the cooling device is calculated using the input finishing rolling speed and a preset temperature model for each cut plate. Then, based on the calculated temperature drop, the preset finish target temperature is converted into the input target temperature. For example, a value obtained by adding the calculated temperature drop amount to the finishing delivery target temperature is set as the entry target temperature.
The temperature drop during finish rolling is a known heat transfer for the temperature effect during finish rolling, taking into account the effects of air cooling, water cooling, roll contact, roll friction, and plastic heat generation determined by the material temperature and plate thickness. Since the temperature can be calculated using a temperature model, the temperature drop amount is calculated using such a known temperature model.

Next, in step S30, a target cooling amount C ^* for the cut plate n is calculated. In step S30, the temperature at the entrance of the finishing mill (for example, the temperature at the position of the entrance thermometer 3) is estimated from the measured value by the second thermometer 5 on the exit side of the roughing mill, and the estimated temperature and step A target cooling amount C ^* is calculated from the deviation from the entry-side target temperature obtained in S20. The obtained target cooling amount C ^* is stored in a table.
The estimated temperature is estimated in consideration of the temperature drop from the second thermometer 5 to the entry-side thermometer 3. In addition, since temperature compensation is performed by appropriately heating the bar heater BH and the edge heater EH on the way, it is possible to estimate the actual temperature in the entry side thermometer 3 with high accuracy.

Further, for example, a value obtained by subtracting the incoming target temperature from the estimated incoming actual temperature is set as the target cooling amount C ^* .
Here, the finishing maximum speed of the finishing rolling speed pattern of the plate 6 to be dealt with is set to the equipment limit speed of the finishing mill 1 or a speed that is lower than the marginal speed as described above.

Next, in step S40, a maximum cooling amount CMAX (maximum cooling amount for the cooling device full discharge pattern) obtained by adding the cooling capacities of all the cooling devices is obtained.
Next, in step S50, it is determined whether or not the target cooling amount C ^* is larger than the maximum cooling amount CMAX. When this determination condition is satisfied (target cooling amount C ^* −maximum cooling amount CMAX> 0), the process proceeds to step S60. On the other hand, if the determination condition is not satisfied, the process proceeds to step S80.

In step S60, when the target cooling amount C ^* is the maximum cooling amount CMAX, the maximum finishing rolling speed at which the cut sheet can be cooled to the finishing delivery target temperature is calculated. The calculated maximum finishing rolling speed is then output to the finishing rolling speed pattern setting unit 12 as the upper limit value of the finishing rolling speed of the cut sheet.
Here, the finishing rolling speed pattern setting unit 12 changes the setting of the finishing rolling speed pattern using the upper limit value of the finishing rolling speed of the subsequent cut plates as the maximum finishing rolling speed calculated in step S60.

Next, in step S70, the current cut sheet (cut sheet with the finished rolling speed changed) is stored, and the target cooling amount C ^* of the cut sheet is changed to the maximum cooling amount CMAX.
In step S80, it is determined whether to set a target amount of cooling C ^* to the switching plate of the tail end of the plate 6 of interest, if it is determined that setting the target amount of cooling C ^* to the end of the switching plate, handle finish. If not, in step S90, it is changed to the next cut plate, and the process proceeds to step S20 to repeat the above process.

In addition, the target cooling amount resetting unit 10Bb operates when a cutting plate targeting the position of the entry-side thermometer 3 passes. And the said target cooling amount resetting part 10Bb is the cutting temperature memorize | stored with the entrance side thermometer 3 with respect to the cut-plate part memorize | stored in step S70 of the said target cooling amount calculating part 10Ba, and the finishing rolling speed after resetting. Based on the above, the target cooling temperature is recalculated and set in the table.
Here, the resetting by the target cooling amount resetting unit 10Bb may not be executed.

"Operation and others"
Fig.4 (a) is the figure which showed the temperature in the finishing mill entrance side of the one plate 6 after rough rolling for every cut plate. The horizontal axis of FIG. 4 shows the position of the cut plate on the tail end side as the left side is the tip of the plate 6 and goes to the right side.
When the single plate 6 is viewed in the cut plate unit in the longitudinal direction, as shown in FIG. 4 (a), the actual temperature of the plate 6 on the entrance side of the finishing mill is lower toward the tail end. This is because the waiting time from exiting the heating furnace to finish rolling becomes longer as it goes to the tail end.

On the other hand, considering the rolling efficiency, the finish rolling speed pattern gradually increases from the tip and reaches the maximum speed on the way, as shown in FIG. 4B, and the finish rolling speed decreases as the tail end is approached. It becomes a speed pattern like this. In addition, the finishing rolling speed | rate of the cut plate shown in FIG.4 (b) has shown with the speed | rate in the 7th stand delivery side of the finishing mill 1. FIG. Here, even when the temperature drop amount of the cut plate is the same, the higher the finish rolling speed, the shorter the cooling time and the larger the required cooling amount (target cooling amount C ^* ).

Then, the target cooling amount C ^* (before changing the setting of the finish rolling speed pattern) for each cut plate based on the actual temperature at the entrance of the finishing mill, taking this finishing rolling speed into account, is also shown in FIG. 4 (a). To do.
The maximum cooling amount CMAX that can be output by the cooling device is also shown in FIG.
Here, with respect to the target plate 6, the finish rolling speed pattern is set as shown in FIG. 4B, with the maximum conveying speed of the plate 6 when the finishing rolling facility is operated at the maximum efficiency as the upper limit. Keep it.

When finishing rolling is performed at the set finishing rolling speed pattern, if the target cooling amount C ^* is within the maximum cooling amount CMAX for all the cut plates, the finishing rolling facility is operated at the maximum efficiency. On the other hand, it is possible to suppress the temperature variation on the delivery side of the finish rolling mill and the variation in the actual temperature from the target temperature on the finish side. In addition, the hot-rolled metal plate 6 of the stable quality can be manufactured, so that the variation in performance temperature is small.

On the other hand, in the case as shown in FIG. 4B, the target cooling amount C ^* exceeds the maximum cooling amount CMAX at the number of cut plates X. When cooling control is performed during finish rolling without changing the setting of the finish rolling speed pattern in this state (when rolling is performed with the finish rolling speed pattern of FIG. 4B), there is insufficient cooling in the portion of the number of cut plates X. Occurs and the variation in actual temperature increases accordingly.

On the other hand, in the present embodiment, the target cooling amount calculation unit 10Ba is based on the actual temperature on the rough rolling delivery side so that the target cooling amount C ^* is equal to or less than the maximum cooling amount CMAX for all the cut plates before finish rolling. Then, the finishing rolling speed pattern is reset. In this embodiment, the resetting process determines whether the target cooling amount C ^* exceeds the maximum cooling amount CMAX in order from the cut plate at the tip of the plate 6 before finish rolling. When a cut sheet having a target cooling amount C ^* exceeding the maximum cooling amount CMAX is detected, when the maximum cooling amount CMAX is set to the target cooling amount C ^* with respect to the cut plate, the finish rolling mill outlet temperature is equal to the above finish. The finish rolling speed at which the delivery target temperature is reached is obtained, and the finish rolling speed pattern is reset with the obtained speed as the maximum finish rolling speed for the transitioned cut plate. In the subsequent cut plates, the finish rolling speed pattern is reset every time a cut plate whose target cooling amount C ^* exceeds the maximum cooling amount CMAX is detected.

Fig.5 (a) is a figure which shows the finishing rolling speed pattern after resetting a finishing rolling speed with respect to the said FIG.4 (b).
By resetting the finish rolling speed pattern as shown in FIG. 5 (a), as shown in FIG. 5 (b), the target cooling amount C ^* of all the cut plates in one plate 6 is the maximum cooling. The amount is CMAX or less. As a result, it is possible to minimize variations in the actual temperature from the target temperature on the finisher side for the temperature record on the finisher side while performing finish rolling as much as possible with the maximum efficiency limited by the finish rolling equipment. Become. That is, the maximum finishing speed that satisfies the finishing output target temperature at the time of entering the finishing mill is obtained, and the cooling device discharge pattern (cooling amount) is determined by reflecting the speed on the finishing rolling speed. Maximum-efficiency rolling can be performed on the rolled material.

Here, the actual temperature at the rough rolling delivery side is estimated, the actual temperature at the finishing mill entry side is estimated and the finish rolling speed pattern is reset, but by performing temperature compensation with the bar heater BH, etc., It is possible to estimate the actual temperature at the entrance of the finishing mill with high accuracy.
Furthermore, in this embodiment, based on the actual temperature of the plate 6 on the finishing mill entry side measured by the entry side thermometer 3, the target cooling amount C ^* is at least for the cut plate whose finishing rolling speed is changed. Perform recalculation. This further improves the accuracy of finish rolling delivery temperature control.

Here, in the above-described embodiment, when a cut sheet having a target cooling amount C ^* exceeding the maximum cooling amount CMAX is detected, when the cut plate is cooled by the maximum cooling amount CMAX, the finish rolling mill discharge side temperature is set to the above-described finishing output. The finish rolling speed at which the target temperature is reached is calculated, and the calculated finish rolling speed is set as the upper limit finishing temperature. And the case where the finish rolling speed pattern was reset so that the maximum value of the finishing rolling speed for the cut sheets after the cut sheet would be the upper limit finishing temperature was exemplified.

However, the resetting process is not limited to this. For example, the finish rolling speed pattern may be reset by restricting the maximum value of the finishing rolling speed of all the cut plates to the upper finishing temperature. In this case, when the target cooling amount C ^* exceeds the maximum cooling amount CMAX with a plurality of cut plates, the smallest value among the above-mentioned upper finishing temperatures at each cut plate is adopted as the upper limit value.
Alternatively, as the resetting process, only the finishing rolling speed of the cut plate portion where the target cooling amount C ^* exceeds the maximum cooling amount CMAX may be reset. The finish rolling speed pattern after resetting in this case is shown in FIG.

  Moreover, in the said embodiment, after resetting a finish rolling speed pattern once, the finish rolling of the board 6 is implemented, However, Finishing rolling about the cut board which the reset processing of the finish rolling speed was complete | finished The finishing rolling speed may be reset for other cut plates. Further, the finishing rolling speed resetting process performed by the target cooling amount calculation unit 10Ba may be performed based on the measured value of the inlet side temperature itself.

Moreover, in the said embodiment, when the target cooling amount C ^{* is made} into the maximum cooling amount CMAX in step S60 of the target cooling amount calculating part 10Ba, the maximum finishing rolling which can cool the cut plate to the finishing side target temperature is possible. It calculates the speed, the maximum finish rolling speed that computed, then as the upper limit of the finish rolling speed of Setsuban, target cooling quantity C ^* suppresses the finish rolling speed of Setsuban portion exceeding the maximum amount of cooling CMAX However, it is not limited to this. For example, the preset finishing rolling speed may be reduced by a preset speed reduction.
Further, the processing of the target cooling amount resetting unit 10Bb may be omitted.
Moreover, in the said embodiment, although demonstrated in the case where the hot-rolled steel plate 6 is made into object, this invention is applicable also to hot-rolled metal plates 6 other than the hot-rolled steel plate 6 as finish rolling object.

DESCRIPTION OF SYMBOLS 1 Finishing rolling mill 2 Cooling device 3 Incoming side thermometer 4 Outlet side thermometer 5 Second thermometer 6 Hot-rolled metal plate 10 Cooling control controller 10A Cooling amount setting adjustment part 10Aa Temperature tracking part 10Ab Spray cooling control part 10B Cooling control Main body 10Ba Target cooling amount calculation unit 10Bb Target cooling amount resetting unit 11 Finish rolling control controller 12 Finish rolling speed pattern setting unit

Claims (5)

While performing finish rolling at a preset finish rolling speed pattern along the longitudinal direction of the hot-rolled metal plate, the plate is cooled by a cooling device, and the plate temperature at the finish rolling mill delivery side is set to the finish delivery target temperature. In the hot finish rolling method to control,
For each cut plate obtained by virtually dividing the plate along the longitudinal direction, from the plate temperature on the finishing mill entry side, the target cooling amount for setting the plate temperature on the exit side of the finishing mill as the finishing target temperature is set to Seeking
It is determined whether the target cooling amount exceeds the maximum cooling amount that can be output by the cooling device, and the finish rolling speed of the cut plate portion that is determined that the target cooling amount exceeds the maximum cooling amount is represented by the finish rolling speed pattern. A hot finish rolling method characterized in that the setting is changed to a finish rolling speed lower than the set finish finish rolling speed.   The maximum finish rolling speed of the above finish rolling speed pattern is set to the maximum finish rolling speed that can be rolled by a finish rolling mill or a finish rolling speed that is lower than the maximum finish rolling speed by a preset margin speed. The hot finish rolling method according to claim 1.   The determination as to whether or not the target cooling amount exceeds the maximum cooling amount is performed before execution of finish rolling of the target hot-rolled metal sheet. Intermediate finish rolling method. If it is determined that the target cooling amount exceeds the maximum cooling amount, the plate temperature at the finishing mill exit side is finished when the cut plate portion determined to exceed the maximum cooling amount is cooled at the maximum cooling amount. The upper limit finishing rolling speed, which is the upper limit of the finishing rolling speed that can be set as the side target temperature, is calculated,
The maximum finishing rolling speed of the preset finishing rolling speed pattern is changed to be equal to or lower than the upper limit finishing rolling speed, and the finishing rolling speed pattern of the target plate is reset. The hot finish rolling method according to claim 3. The hot finish rolling method according to claim 4, wherein when the finish rolling speed pattern is reset, the target cooling amount is recalculated.

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