JPH0890037A - Control method for coiling temp. of hot rolling - Google Patents

Abstract

PURPOSE: To precisely control a target coiling temp. with reduced computing quantity in the case a passing speed is rapidly changed in coiling a rolled sheet by a coiler. CONSTITUTION: When a rolled sheet finished by hot rolling process is introduced into a cooling equipment and is coiled to the prescribed coiling device while pouring cooling water to rolled sheet, while a pouring quantity (pouring distance) is estimated, at a virtual cut sheet of the prescribed length set to rolled sheet, based on the measured temp. at the outlet side of finish rolling mill and the passing speed set beforehand, the water pouring to virtual cut sheet is executed. The water pouring quantity 6 for the virtual cut sheet, in which a passing speed 1 is accelerated in linear like B, is in a simple way set to the value linearly increasing/decreasing, an error 7 from the target temp. generated as a result is compensated to the adjusting zone arranged at the latter part of cooling equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot rolling coiling temperature control method, and particularly to hot rolling suitable for winding a rolled plate such as a rolled steel plate produced by a hot rolling process into a coiler. The present invention relates to a winding temperature control method.

[0002]

2. Description of the Related Art Generally, in hot rolling, a steel plate rolled to a desired thickness by a finishing mill is finally wound around a coiler, but the product quality is maintained during the winding. In order to prevent this, cooling to a predetermined winding temperature is performed. The control of the winding temperature in this hot rolling process is usually performed by a cooling facility arranged between the finish rolling mill and the coiler.

FIG. 6 conceptually shows the positional relationship of these facilities. Cooling is provided between the final stand SF of the finish rolling mill and the coiler 10 for winding the steel sheet S rolled by the finish rolling mill. A facility 12 is provided, and between the final stand SF and the cooling facility 12, the finish rolling mill outlet side temperature (Fin of the steel sheet S
ishar Delivaly Temperature (hereinafter also referred to as FDT)
An FDT meter 14 for measuring the temperature is also provided between the cooling equipment 12 and the coiler 10 (Coiling Temperature).
re, hereinafter also referred to as CT) CT meter 16 for measuring
Is installed.

Inside the cooling equipment 12, a large number of water injection headers 1 are provided above and below the steel plate S traveling in the direction of the arrow, as schematically shown in the perspective view of FIG.
8 (indicated by a straight line extending in the width direction of the steel plate S) are arranged. In each of these water injection headers 18, a plurality of nozzles 1 are opened by opening / closing a valve (actuator) 20.
8A (indicated by 7 straight lines perpendicular to the upper or lower surface of the steel plate S in the figure), cooling water (indicated by a mesh pattern in the figure) is sprayed (water injection) on both front and back surfaces of the steel plate S. In addition, all water injection headers have substantially the same cooling capacity.

The steel sheet S is cooled by the cooling equipment 12 and CT
When the CT measured by the total 16 is controlled to be constant, conventionally, as shown in FIG. 8, virtual cutting plates i 1, i +1, i +2, ... ··· Considering the temperature of the steel plate S with the FDT meter 14 for each virtual cutting plate (or predicting), and considering the FDT and fluctuations in the strip running speed predicted from the schedule until winding by the coiler 10. Then, an appropriate amount of water injection (cooling amount) is estimated, and the valve 20 is opened / closed in accordance with the timing at which the virtual cutting plate reaches the amount of water injection (actually, there is a response delay such as opening / closing of the valve. The water injection distance (the number of headers 18 for injecting the cooling water from the inlet side to the outlet side of the cooling facility 12) is adjusted by first advancing appropriately.

By the way, generally, in a finish rolling mill in a hot rolling line, rolling is performed while changing the speed according to a rolling schedule represented by a rolling speed that changes with time as shown in FIG. That is, after the start of rolling, until the tip of the steel plate S is wound around the coiler 10, a constant low speed A
After rolling, the speed is changed to a high speed state C through an acceleration state B of a substantially constant acceleration rate to reduce the rolling time, and after maintaining that state, a deceleration of a substantially constant deceleration rate is applied to adjust the coil shape. After the state D, the low speed state E is set, and the rolling is finished after a lapse of a predetermined time.

When finish rolling according to the rolling schedule shown in FIG. 9, the speed of the steel sheet S passing through the cooling equipment 12 also changes substantially at the same fluctuations as the rolling speed shown in FIG. . Therefore, when the FDT of the virtual cutting board measured by the FDT meter 14 is constant, the same C
Since the amount of cooling (cooling time) required to achieve T may be constant, the sheet steel S passes through the cooling facility 12 in accordance with fluctuations in speed (passing speed), that is, the speed in FIG. The opening / closing of the valve 20 may be controlled so that the water injection distance is proportional to the fluctuation.

However, in the actually measured FDT, as shown in FIG. 10, the skid mark SM on which the temperature of the steel plate S periodically fluctuates in the length direction (from tip to tail end) with respect to the target FDT, the tail end side is Rundown RD, which has a lower temperature than the tip side,
On the contrary, the fluctuations are caused by the run-up RU or the like in which the tail end side becomes hotter than the tip end side. Where skid mark S
M is a periodic temperature fluctuation that occurs corresponding to the skid position because the slab was placed on a skid and heated by a heating furnace (not shown) before finish rolling, and rundown R
When the slab discharged from the heating furnace is rolled, there is a difference in rolling start time between the tip end and the tail end, and therefore D is a variation due to the fact that the rolling start is delayed as it is closer to the tail end, and the slab is cooled. The run-up RU is a fluctuation caused by the fact that the degree of cooling during the rolling by the finish rolling mill decreases due to the acceleration of the rolling speed, which exceeds the degree of run-down.

As described above, since the FDT actually measured on the exit side of the finish rolling mill is actually fluctuating, the virtual cutting plates i, i +
For each 1, i +2, ..., measured FDT and speed fluctuation until winding (including difference in air cooling amount due to difference in strip running time)
The water injection distance estimated based on the
_As shown in FIG. 11, the relationship between _i , t _{i + 1} , t _{i + 2} , ... Is different for each virtual cutting board.

FIG. 12 shows the FDT for each virtual cutting plate when the finish rolling is executed according to the schedule shown in FIG.
The water injection distance (the number of water injection headers that open the valves in the cooling maintenance 12) obtained by the estimation calculation based on the FDT actually measured by the total 14 and the predicted plate passing speed, etc. It is a graph which showed notionally for every virtual cutting board. In this figure, as the elapsed time is shorter, the number i of the virtual cutting plate is smaller. Therefore, the water injection distance is displayed on the left side of the virtual cutting plate having the smaller number.

As described above, the water pouring distance is estimated and calculated for each virtual cutting plate, and the water pouring distance (water pouring amount) is calculated by opening and closing the valve at a timing corresponding to the virtual cutting plate based on the estimation result. In the rolling schedule shown in FIG. 9 in the rolling schedule shown in FIG. 9 such that the steel sheet S is controlled to have the same winding temperature. Now, the case where the speed fluctuates to a high constant speed state will be examined in more detail.

FIG. 13 shows, as shown in Graph 1, the strip running when the rolling schedule is linearly accelerated from a low speed state to a high speed state like A → B → C as in the rolling schedule shown in FIG. The relationship between speed, water injection distance (water injection end position in the figure) and coiling temperature error is shown in a simplified manner, ignoring thin FDT fluctuations. From the constant speed state of A to the acceleration state B to C
Although the speed is changed to the constant speed state of No. 2, if the water injection distance is the same without changing as in Graph 2, an error as shown in Graph 3 will occur in the coiling temperature by the coiler. Become. This error becomes larger as the speed difference before and after acceleration becomes larger, and sometimes becomes 100 to 200 ° C. In order to make this error approximately 0 ° C. as shown in Graph 4, it is necessary to correspond to the temperature fluctuation in Graph 3. The water injection distance setting must be changed as shown in Graph 5. Although such a change in the setting of the water injection distance is the reverse of the phenomenon, C → in FIG.
It is also necessary when decelerating as D → E.

[0013]

However, in order to properly estimate and change the water injection distance according to the speed fluctuation as described above, the allowable winding temperature error is ΔT [° C]. For example, it is necessary to estimate and calculate the water pouring distance such that the actual error falls within this range by performing complicated calculation processing such as repeated convergence calculation in a short time (Δt) for each virtual cutting plate.

That is, in the constant speed states A and C, since the winding temperature error is relatively small, there is no problem, but the water injection distance (water injection amount) according to the speed fluctuation is estimated for each virtual cutting plate, When the cooling water is sprayed from the water injection header 18 to the steel plate S to control the winding temperature, even if there is no large fluctuation in the FDT, if an equal control accuracy is always attempted, the acceleration rate of the strip running speed is increased. The larger (or the deceleration rate) or the plate passing speed itself, the smaller the length of the virtual cutting plate, which is the unit of calculation, must be reduced.

As a result, the calculation cycle Δt becomes short, and the calculation processing by the CPU (central processing unit) of the controller for controlling the cooling equipment may not be in time, which makes it impossible to control the winding temperature with high accuracy. There is. This problem becomes more serious as the temperature calculation model formula (estimation formula) used for estimating the water injection amount becomes complicated, and the amount of calculation processing by the CPU increases accordingly. This means that the calculation cycle has a limit determined by the calculation processing capacity of the controller and the calculation amount required for one estimation.

The present invention has been made to solve the above-mentioned conventional problems, and when winding a rolled sheet to be hot-rolled according to a schedule with a coiler, even if the stripping speed changes abruptly, An object of the present invention is to provide a hot rolling coiling temperature control method capable of controlling the coiling temperature to a target coiling temperature with high accuracy without increasing the calculation processing capacity.

[0017]

Means for Solving the Problems The present invention, when a rolled sheet finish-rolled in a hot rolling process is introduced into a cooling facility and cooling water is poured into the rolled sheet to cool it to a predetermined coiling temperature,
Estimate the injection amount of cooling water for each virtual cutting plate of a predetermined length that is virtually set on the rolling plate based on the measured finish rolling mill outlet temperature and the preset strip passing speed, and estimate In the hot rolling coiling temperature control method of pouring the cooling water of the specified water injection amount into the virtual cutting plate in accordance with the timing when the corresponding virtual cutting plate arrives, pouring is performed on the virtual cutting plate whose passing speed is fluctuating. The amount of water is changed from the amount of water injection before change calculated in advance based on the measured or predicted exit side temperature of the finishing mill and the set strip passing speed to the amount of water injection after change calculated in the same way. The problem is solved by simply setting a value that gradually increases or decreases at an arbitrary rate.

In the winding temperature control method according to the present invention, the amount of water injected to the virtual cutting plate in which the strip passing speed is linearly varying is simply set to a value that linearly increases or decreases. Is.

Further, in the present invention, in the above-described winding temperature control method, an error from the target winding temperature, which is predicted to be generated from the finish rolling mill outlet side temperature measured during the fluctuation of the strip running speed, is simply set. The adjustment zone is provided in the cooling equipment behind the control zone that injects the amount of cooling water.

[0020]

In the present invention, the amount of water injected to the virtual cutting plate whose passage speed is changing is simply set to a value that gradually increases or gradually decreases from the amount of water before change to the amount of water after change. Therefore, the amount of water injection before and after the change is applied to the estimation formula by the FDT and the strip running speed, which are actually measured or predicted, and highly accurately determined in advance, and during the change, the amount of water injection before the change finally changes. It is possible to sequentially change the amount of water to be injected later in accordance with the ratio of speed fluctuations obtained in advance.

Therefore, during the fluctuation, it is sufficient to add the value obtained by multiplying the difference in the amount of water before and after the fluctuation by a predetermined ratio to the amount of water before the fluctuation, and thus the time is calculated by the same method for each virtual cutting plate. Since the amount of calculation can be significantly reduced compared to the case of performing a costly estimation calculation, even if the rate of change in speed is large, highly accurate winding temperature control can be performed without increasing the processing capacity of the controller. It becomes possible to do.

Further, in the present invention, when the water injection amount for the virtual cutting plate in which the strip passing speed is linearly changing is simply set to a value that linearly gradually increases or decreases, it is set while the strip passing speed is changing. Since it is possible to obtain the water injection amount by a simple proportional calculation, it becomes easier for the controller to perform the calculation process. Therefore, it is possible to very effectively cope with monotonous and continuous fluctuations such as speed fluctuations set as a rolling schedule.

Further, in the present invention, the error from the target coiling temperature, which is predicted to be generated from the temperature on the exit side of the finish rolling mill actually measured during the fluctuation of the strip running speed, is injected with the cooling water of the amount that is simply set. When compensating in the adjustment zone provided in the cooling equipment behind the control zone, even if there is an error due to cooling by calculating the water injection amount set during the fluctuation of strip running speed by the above-mentioned simple calculation, Since the cooling, which requires a rapid correction of the water injection amount with time, has already been completed based on the above-mentioned simple calculation, both the inclination and the magnitude of the fluctuation are small. Therefore, it is possible to lengthen the calculation cycle for calculating the water injection amount that compensates for the above error, so that it is possible to calculate the water injection amount using an accurate estimation formula, and apply the water injection amount to reduce the error. Because it can be resolved,
It is possible to control the winding temperature with extremely high accuracy.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a drawing corresponding to FIG. 6 conceptually showing the arrangement of cooling equipment applied to one embodiment according to the present invention, and FIG. 2 is a winding temperature control method of this embodiment. FIG. 14 is a diagram conceptually showing the characteristics of FIG.

As in the conventional case, the cooling equipment 12 applied to the present embodiment has therein a large number of water injection headers 18 arranged in the traveling direction of the steel plate S, as shown in FIG. By opening and closing the valve 20, the water injection header 18
The cooling water pouring distance (water pouring amount) can be corrected, and the cooling zone over the entire length of the cooling equipment 12 is the upstream control zone 12A and the downstream adjustment zone 12B. Separated, the water injection distance in each zone is adjusted independently.

Similar to the case of FIG. 13, the winding temperature control method of the present embodiment is characterized in that the passing speed varies from A to C through an acceleration state B as shown in FIG. Will be explained.

In this embodiment, in the control zone 12A, the water injection distance is set to change with respect to the virtual cut plate as shown in Graph 6, and the valve is opened and closed in accordance with the timing when the virtual cut plate reaches. After that, the number is adjusted, and the steel plate S is cooled by correcting the water injection distance set for each virtual cutting plate.

In this embodiment, when the strip running speed is in the low speed state A and the high speed state C, the FDT is actually measured as in the conventional case, and the water injection distance is estimated and calculated using the actually measured FDT and set. However, after the passage speed starts to accelerate linearly, the water injection distance is increased linearly as follows.

The water pouring distance at low speed set before acceleration is accurately estimated in advance based on the measured (or predicted) FDT and the strip speed determined from the schedule, and the water pouring distance at high speed is set after acceleration. Is accurately estimated and calculated in advance by a method described later based on the predicted FDT and the strip running speed determined from the schedule, and the water injection distance set after the strip running speed is accelerated is set to the start point 6S at the same time as the acceleration start point 1S. It is calculated as a value that linearly changes from the end point to the end point 6E.

That is, the water injection distance in the case of passing through all the cooling zones at a speed before acceleration and a speed at which acceleration is completed is obtained in advance by highly accurate processing, and then the water injection distance before and after acceleration can be applied. While seeking each range,
The time range for changing the water injection distance is determined by the simple method of setting the water injection distance calculated by the simple calculation that linearly connects both water injection distances. The water injection distance set by this simple calculation is shown in FIG. 3 in correspondence with FIG.

This estimation operation is a model expression (because it is complicated, omitted) according to the flow shown in the block diagram of FIG.
The temperature T of the target point is calculated by applying the steel plate specifications (thickness, etc.), FDT, ON / OFF combination of the water injection header determined from an arbitrary water injection distance, the moving time in the cooling equipment, etc. Then, the calculated temperature T is compared with the target temperature T0, the temperature calculation is repeated while increasing or decreasing the water injection distance until the absolute value of the difference δ converges to a value smaller than the allowable error δ0, and the water injection distance at the time of convergence is calculated. This can be done by using an estimated value.

The reason for performing the simple calculation for linearly varying the water injection distance as described above will be described. The linear variation of the water injection distance in this embodiment means that the water injection time for each virtual cutting plate is constant. If the water injection time is kept constant, the temperature drop due to water cooling will be almost constant, but the air cooling time will change linearly with linear velocity fluctuations, and the temperature drop due to air cooling will change substantially linearly. By making the water injection time constant when the speed changes (that is, changing the water injection distance linearly), the overall temperature drop amount can be changed substantially linearly.

In the present embodiment, the time point 6S at which the change of the water injection distance is started is set at the same time as the time point 1S at which the acceleration of the strip passing speed is started in order to facilitate the control, but the change of the water injection distance is completed. The time point 6E is set after a lapse of time ΔE from the time point 1E at which the acceleration of the strip passing speed is completed. This time ΔE is the time required for the part that has entered the cooling zone at the end of acceleration to leave the cooling zone.

The water injection distance of the graph 6 shown in FIG.
It can be easily obtained by the above-mentioned method, and can be repeatedly used if it is calculated once for a rolled plate of the same kind and determined.

When the plate passing speed changes linearly as described above, the water injection distance that changes linearly is set, and the timing (time) for operating the water injection valve is determined so that each water injection distance is reached. The steel sheet S is cooled by opening the valve 20 at the timing.

By the way, during the speed fluctuation, the control zone 12A
Then, when the valve 20 is adjusted so as to have the water injection distance of the above graph 6, the actually required water injection distance (shown by the broken line in FIG. 2) shown as the graph 5 in FIG. 13 and the graph 6 Since there is a difference between the linearly increasing water injection distance shown by, the error of the winding temperature shown as a graph 7 in FIG. 2 occurs.

The above-mentioned error is smaller than ΔT ° C as shown in FIG. 13, because both the inclination and the magnitude of the variation are smaller than the temperature variation when the water injection distance is set in Graph 5. The frequency of calculation required to achieve the control accuracy of the coiling temperature is reduced, and the calculation cycle Δ
Since it becomes possible to take a long t, it becomes easy to deal with the calculation processing by a complicated estimation formula, and it is possible to realize highly accurate control.

In the present embodiment, the winding temperature error caused by the above-mentioned simple method is corrected in the adjustment zone 12B provided on the downstream side of the cooling equipment.

In this compensation method, for example, for each virtual cutting plate, the current temperature is appropriately calculated based on the actually measured FDT and the actual speed and water injection status while existing inside the control zone 12A. The error is eliminated by estimating the water injection distance (water injection amount) required for correction based on the calculated temperature at the obtained current position and the expected speed thereafter, and setting the water injection distance as the water injection amount in the adjustment zone 12B. The estimation operation of the water injection distance here is similarly performed according to the above-described calculation procedure by replacing "FDT" in (2) with "calculation temperature at the current position" in the flow shown in FIG. You can

FIG. 1 when the method of this embodiment is applied.
FIG. 5 conceptually shows the water injection distance set for each virtual cutting plate corresponding to 2. “Water injection by simple calculation” performed in the adjustment zone shown in this figure means that water is previously supplied at some fixed water injection distance so that the water injection distance can be increased or decreased when the water injection distance is compensated.

According to this embodiment described in detail above, for example,
In hot rolling coiling temperature control for ordinary steel, there are cases in which it is difficult to execute complex processing in a proper cycle, which was caused by the computational load on the CPU of the conventional controller. However, it is possible to eliminate this, and by performing high-precision calculation processing only for the adjustment zone at appropriate timing, it is possible to achieve high-precision winding temperature control.

The present invention has been specifically described above, but the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the scope of the invention.

For example, in the above embodiment, the case where the water injection amount is the water injection distance has been described, but the water injection amount may be corrected by adjusting the opening degree of the actuator such as the nozzle.

Further, according to the present invention, not only the monotonous acceleration / deceleration such as the acceleration in the first half and the deceleration in the latter half of the rolling schedule shown in FIG. It may be applied to a zigzag threading plate in which acceleration and deceleration are alternately and repeatedly switched in a short time.

The actuator for allowing cooling water to be injected is not limited to the valve.

[0047]

As described above, according to the present invention,
When rolling a rolled sheet that is hot-rolled according to a schedule with a coiler, even if the stripping speed changes abruptly, control the target winding temperature with high accuracy without increasing the calculation processing capacity of the controller. You can

[Brief description of drawings]

FIG. 1 is an explanatory view showing a positional relationship of cooling equipment in a hot rolling line applied to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a winding temperature control method of the present embodiment.

FIG. 3 is a diagram showing the features of this embodiment.

FIG. 4 is a block diagram showing a procedure for estimating and calculating a water injection distance.

FIG. 5 is an explanatory view conceptually showing the water injection distance over the entire length when this embodiment is applied.

FIG. 6 is an explanatory diagram showing a layout relationship of conventional cooling equipment.

FIG. 7 is a perspective view showing an outline of a main configuration inside a cooling facility.

FIG. 8 is a diagram for explaining a virtual cutting board.

FIG. 9 is a diagram showing speed fluctuations due to a general rolling schedule.

FIG. 10 is a diagram for explaining the cause of FDT fluctuation.

FIG. 11 is a diagram for explaining a conventional setting condition of a water injection distance.

FIG. 12 is a diagram corresponding to FIG. 4, showing a water injection distance set in a cooling facility in conventional finish rolling.

FIG. 13 is a diagram for explaining the problems of the conventional winding temperature control method.

[Explanation of symbols]

 10 ... Coiler 12 ... Cooling equipment 12A ... Control zone 12B ... Adjustment zone 14 ... FDT meter 16 ... CT meter 18 ... Water injection header 20 ... Valve

Claims (3)

[Claims] 1. When a rolled plate finish-rolled in a hot rolling process is introduced into a cooling facility and cooling water is poured into the rolled plate to cool it to a predetermined coiling temperature, For each virtual cut plate of a predetermined length virtually set on the plate, it is estimated based on the measured finish rolling mill outlet temperature and the preset strip passing speed, and the estimated amount of cooling water is In the hot rolling coiling temperature control method in which water is poured into the virtual cutting plate at the timing when the corresponding virtual cutting plate arrives, the water injection amount for the virtual cutting plate whose striping speed is fluctuating is measured or predicted. From the water injection amount before the change which is estimated and calculated in advance based on the finish rolling mill outlet temperature and the set strip passing speed,
Similarly, a hot rolling coiling temperature control method is characterized in that it is simply set to a value that gradually increases or decreases gradually at an arbitrary ratio toward the estimated and calculated changed water injection amount. 2. The hot rolling coiling temperature according to claim 1, wherein the water injection amount for the virtual cutting plate in which the strip passing speed is linearly changing is simply set to a value that gradually increases or decreases linearly. Control method. 3. The cooling water according to claim 1 or 2, wherein an error from a target winding temperature, which is predicted to be generated from the temperature on the exit side of the finish rolling mill actually measured during the fluctuation of the strip running speed, is simply set as the cooling water. A hot rolling coiling temperature control method, characterized in that compensation is performed in an adjusting zone provided in a cooling facility behind a control zone for water injection.