WO2011122070A1

WO2011122070A1 - Rolling of metal strip

Info

Publication number: WO2011122070A1
Application number: PCT/JP2011/050785
Authority: WO
Inventors: 小川　茂; 比護　剛志; 邦彦若月
Original assignee: 新日本製鐵株式会社
Priority date: 2010-03-31
Filing date: 2011-01-12
Publication date: 2011-10-06
Also published as: KR20120127511A; KR101300237B1; EP2554284A1; CN102834192A; BR112012024207A2; EP2554284A4; TW201139001A; TWI401123B; EP2554284B1; CN102834192B

Abstract

Disclosed is a method for rolling in a rolling mill which has a bending decreasing device with a responsivity lower than that of a bending increasing device, the method intended for realizing a quick-response strip crown and shape control function even under a setting condition in which roll bending decreasing force is applied. To solve the aforementioned challenge, the method is executed as follows. Before starting rolling, both bending increasing force and bending decreasing force are applied to allow the resultant force, or roll bending force equivalent to roll balance force, to act upon a work roll chock. At the start of rolling, the bending increasing force is varied with the bending decreasing force kept at a constant value, allowing the resultant force or predetermined roll bending force (bending decreasing force) to act on the work roll chock for rolling. At the end of the rolling, the bending increasing force is reset to the pre-rolling value, and as the resultant force with the bending decreasing force, the roll bending force equivalent to the roll balance force is exerted on the work roll chock, allowing the rolling to end under this condition.

Description

Metal plate rolling method

The present invention relates to a rolling mill for metal sheet material, and relates to a rolling mill capable of imparting a high response and strong roll bending force. In particular, the present invention relates to a method for rolling a metal sheet that can provide a highly responsive sheet crown and shape control function even in a multi-stage rolling mill in which the response of the decrease bending apparatus is lower than that of the increment bending apparatus.

Roll bending for imparting bending force to work roll chock and roll shift for displacing the roll in the roll axis direction as a control method when performing plate crown and shape control rolling in a multi-high rolling mill such as a 4-high rolling mill or a 6-high rolling mill There is a roll cross that gives a cross angle to the roll.

Among these control methods, it is difficult to quickly change the setting of roll shift and roll cloth during rolling. For this reason, it is not suitable for sheet crown / shape control rolling that requires control during rolling. On the other hand, the roll bending apparatus controls the hydraulic pressure and can change the roll bending force during rolling, and is therefore suitable for plate crown / shape controlled rolling.
Patent Document 1 describes a method of continuously rolling a rolled material obtained by joining steel materials having different sheet widths, sheet thicknesses, steel types, and the like using a hot finish rolling mill having a roll bending mechanism and a roll shift mechanism. Yes. However, since the change speed of the roll shift position is very slow compared to the change speed of the roll bending force, the roll shift position is fixed during rolling, and the crown control is performed only with the roll bending force with high responsiveness. is there.

In this case, the plate crown / shape control is controlled by the control speed of the roll bending apparatus, and conventionally, high response is desired for the roll bending apparatus.
Patent Document 2 describes that it is the secondary pipe length of the servo valve that determines the responsiveness of the roll bending apparatus (see paragraph [0014] of FIG. 1 and FIG. 1). For this reason, the bending force is controlled by a servo valve that controls the difference in hydraulic pressure between the increase side and the decrease side. In order to ensure high responsiveness, these servo valves are arranged on the side of the housing post at a total of four locations on the drive side and the operation side of the rolling mill housing, and from each servo valve to the hydraulic cylinder. The piping length is up to 2m.

JP-A-6-55207 JP-A-8-215730

However, it is not only the pipe length from the servo valve to the hydraulic cylinder that determines the responsiveness of the roll bending apparatus.
For example, the rolling mill shown in FIG. 1 is a four-high rolling mill provided with a pair of upper and lower work rolls 1-1 and 1-2 and a pair of upper and lower reinforcing rolls 2-1 and 2-2 for supporting them. Increment bending devices 6-1 to 6-4 are incorporated into project blocks 5-1 and 5-2, and decrease bending devices 7-1 to 7-4 are incorporated into upper and lower reinforcing roll chocks 4-1 and 4-2. This type of rolling mill. In this type of rolling mill, the response speed of the decrease bending apparatus is delayed as compared with the response speed of the increment bending apparatus.
Therefore, when the increase bending force is applied to the work roll for the plate crown and shape control, it is possible to control with high response.However, when the decrease bending force is applied, it can be quickly performed during rolling. The setting cannot be changed. Therefore, disturbance factors that change during rolling, such as the rolling material entry side plate thickness and the rolling material temperature, cannot be removed, and the product quality and the yield may be reduced.

Moreover, the reason why the response of the decrease bending apparatus does not increase is because the fixed pipe cannot be used. That is, since the work roll is more easily worn than the reinforcing roll by rolling operation, it is necessary to periodically change the roll. However, since the rolling mill shown in FIG. 1 incorporates the increment bending device into the project block, it is not necessary to attach or detach the hydraulic piping of the increment bending device every time the roll is changed. Can be connected. Thus, a servo valve for high response hydraulic control can be employed. On the other hand, since the decrease bending apparatus of the rolling mill shown in FIG. 1 is incorporated into the upper and lower reinforcing roll chock, the hydraulic piping of the decrease bending apparatus must be attached and detached each time the roll is changed. Since there is a high possibility that minute foreign matters will be mixed in the hydraulic piping when the hydraulic piping is attached or detached, it is not possible to employ a servo valve for high response hydraulic control. In addition, since the hydraulic control valve must be connected via a flexible and detachable hydraulic piping such as a flexible piping, fluctuations in the hydraulic pressure to be transmitted may be absorbed and relaxed.
That is, it can be connected to the hydraulic control valve via a fixed hydraulic pipe, or it must be connected to the hydraulic control valve via a flexible and detachable hydraulic pipe such as a flexible pipe. This is the biggest cause that the response of the decrease bending apparatus must be lower than the response of the increase bending apparatus.

Also, since the decrease bending device cannot be controlled with high response, rolling becomes unstable at the start of rolling, when the bending bending force is applied at the end of rolling, and when released, causing product quality to deteriorate and productivity to decrease. ing.
That is, the decrease bending force cannot be applied during idling when no rolling load is applied. Therefore, it is necessary to quickly apply the decrease bending force at the start of rolling, while it is necessary to quickly return to the roll balance state at the end of rolling. Here, when the roll bending force is changed under the control of a decrease bending device having poor responsiveness, a predetermined defect bending force is not applied to the leading end of the rolled material, and the defective shape portion becomes long. .
That is, the second finding is that when the decrease bending bending force is applied to the rolling mill of the type shown in FIG. 1, it is difficult to quickly change the setting during rolling. This is because disturbance factors that change during rolling, such as material temperature, could not be removed, and product quality and yield were reduced.

The problem to be solved by the present invention is that, in a rolling mill in which the response of the decrease bending apparatus is lower than the response of the increase bending apparatus, even when the decrease bending force is applied to the work roll, It is providing the rolling method of the metal plate material which can provide a shape control function.

As a result of intensive studies to solve the above problems, the present inventor has found that the bending force due to the resultant force of both bending devices is a rolling mill in which the response of the decrease bending device is lower than the response of the increment bending device. It has been found that the control during rolling and rolling is performed only by the highly responsive increment bending apparatus, thereby enabling highly responsive sheet crown and shape control, and the present invention has been achieved.
That is, when a decrease bending force is applied as a work roll bending force for the purpose of plate crown and shape control, a highly responsive incremental bending device is used to change the roll bending force at the start and end of rolling. Rolling method. This means that a highly responsive increase bending apparatus can compensate (cover) the responsiveness of the decrease bending apparatus.
In addition, it is possible to build a good plate crown and shape by controlling with a highly responsive increment bending device against disturbances that change during rolling, such as the rolling material entry side plate thickness and rolling material temperature. Product quality and productivity can be significantly improved.

For example, the rolling mill shown in FIG. 1 is a rolling mill having a structure in which a flexible and detachable hydraulic pipe is adopted as the hydraulic pipe of the decrease bending apparatus because of easy attachment / detachment of the pipe at the time of roll replacement. As a result, the responsiveness of the decrease bending apparatus must be lower than the responsiveness of the increment bending apparatus. However, since this rolling mill has a structure in which an increase bending device is provided in the project block, a large capacity increase bending device can be provided in the project block, and the hydraulic pressure can be obtained through a fixed hydraulic pipe. Since it can be connected to a control valve, it has an excellent characteristic that it can be an ink-bending device with high responsiveness. Therefore, the roll bending force control with high responsiveness can be performed.

Based on these findings, the present inventor is able to provide a metal crown that can provide a highly responsive plate crown and shape control function even in a rolling mill in which the response of the decrease bending apparatus is lower than that of the increment bending apparatus. Invented a method of rolling plate materials. The gist is as follows.

(1) In a rolling mill having an increment bending apparatus that generates an increase bending force and a decrease bending apparatus that generates a decrease bending force, the response of the decrease bending apparatus is higher than that of the increase bending apparatus. A method of rolling a metal sheet using a low rolling mill,
Before starting rolling, both the increase bending force and the decrease bending force are applied, and a roll bending force corresponding to the roll balance force is applied to the work roll chock as a resultant force.
After that, while changing the decrease bending force so as to become the decrease bending force during the predetermined rolling, the increase bending force is changed so that the resultant balance of the decrease bending force and the increase bending force maintains the roll balance force. Let In this step, the increase bending force is applied to the work roll chock so that the decrease bending force is initially set as the decrease bending force during rolling, and the resultant balance of the decrease bending force and the increase bending force becomes the roll balance force. If you let it, you can omit it.
After that, at the start of rolling, the increase bending force is changed to the work roll chock as a resultant force while changing the increase bending force while continuing the control of maintaining the decrease bending force during the predetermined rolling. Make it work.
During rolling, by controlling the increment bending force, the rolling is performed so as to maintain the work roll bending force during the predetermined rolling,
Thereafter, at the end of rolling, the increment bending force is changed, and the roll bending force corresponding to the roll balance force is applied to the work roll chock as a resultant force with the decrease bending force, and the rolling of the metal plate material is finished in this state.
Thereafter, the decrease bending force and the increase bending force are decreased so as to maintain the roll balance force as the resultant force. This step also maintains the decrease bending force during the specified rolling, and the increase bending force is set so that the resultant balance of the decrease bending force and the increase bending force becomes the roll balance force. Can be omitted if it works.
It is the rolling method of the metal plate material characterized by the above.
(2) The rolling mill includes at least a pair of upper and lower work rolls and a pair of upper and lower reinforcing rolls that respectively support the upper and lower work rolls, and an increase hydraulic cylinder constituting the increase bending apparatus for each of the upper and lower work rolls is fixed. Connected to each hydraulic control valve via a hydraulic pipe, and incorporated into a project block projecting inside the rolling mill housing,
Further, the decrease hydraulic cylinder constituting the decrease bending apparatus for at least the upper work roll is connected to the hydraulic control valve via a flexible and detachable hydraulic pipe and has a structure incorporated into the upper reinforcing roll chock. It is a rolling machine, Comprising: The rolling method of the metal plate material as described in (1) characterized by performing using the said rolling mill.

(3) Measure the hydraulic pressure in the decrease hydraulic cylinder or in the hydraulic piping connected to the cylinder, and based on the measured value, increase the bending bending force so that the roll bending force acting on the work roll chock becomes a predetermined value. The method for rolling a metal sheet according to (2), wherein the method is controlled.
Here, the predetermined value of the roll bending force is a roll bending force value obtained in advance from rolling conditions and the like. Further, the roll bending force acting on the work roll chock is a resultant force of the increment bending force and the decrease bending force.

In the rolling method according to the present invention, the roll bending force at the start of rolling and at the end of rolling is changed using an increase bending responsive apparatus.
For this reason, by adopting a flexible and detachable hydraulic piping for the hydraulic piping of the decrease bending device due to the ease of piping attachment and detachment at the time of roll replacement, the response of the decrease bending device can be improved. Even in rolling mills with lower responsiveness, the high-responding increment bending device can compensate for the responsiveness of the decrease bending device, thereby providing a highly responsive and powerful plate crown and shape control function. it can.
Therefore, according to the rolling method of the present invention, it is possible to build a good plate crown and shape against disturbances that change during rolling, such as the rolled material entry side plate thickness and the rolled material temperature, and the product quality And the yield can be greatly improved.

It is a side view which shows an example of the structure of the rolling mill which this invention makes object. It is a figure which shows an example of the operation flow of the rolling method which concerns on this invention. It is a figure which shows time-sequential changes, such as roll bending force accompanying the operation flow of FIG. It is a figure which shows time-sequential changes, such as roll bending force, when the responsiveness of a decrease bending apparatus is low. It is a figure which shows another example of the operation flow of the rolling method which concerns on this invention. It is a figure which shows time-sequential changes, such as roll bending force accompanying the operation flow of FIG. It is a side view which shows another example of the structure of the rolling mill which this invention makes object. It is a side view which shows another example of the structure of the rolling mill which this invention makes object.

Hereinafter, the rolling method according to the present invention will be described with reference to FIGS.
FIG. 1 is a side view showing an example of the structure of a rolling mill targeted by the present invention, and this rolling mill will be described as an example. As shown in the figure, the rolling mill targeted by the present invention includes a pair of upper and lower work rolls 1-1 and 1-2 and a pair of upper and lower reinforcing rolls 2-1 and 2-2 for supporting them. It is a multi-stage rolling mill.
In addition, although the rolling mill shown in the figure is a four-high rolling mill of the type adopted for a finishing tandem rolling mill of a thin steel plate strip or the like, it is not limited to this and may be a six-high rolling mill.

In this rolling mill, the upper increment bending devices 6-1 and 6-2 that apply an increase bending force to the upper work roll 1-1, and the lower operation load that applies an increase bending force to the lower work roll 1-2. Increment bending apparatuses 6-3 and 6-4 are incorporated in project blocks 5-1 and 5-2 protruding inside the housing 9.
For this reason, the work rolls 1-1 and 1-2 require periodic roll reassignment due to wear and tear due to rolling operation. However, the rolling mill of FIG. 1 does not need to attach or detach the hydraulic piping of the increment bending apparatus every time the roll is reassigned. Each of the increment bending apparatuses 6-1 to 6-4 can be connected to each hydraulic control valve via a fixed hydraulic pipe, thereby adopting a servo valve for high response hydraulic control. be able to. Therefore, it is possible to provide an incremental bending apparatus with high responsiveness.

On the other hand, the upper decrease bending apparatuses 7-1 and 7-2 for applying a decrease bending force to the upper work roll 1-1 are incorporated in the upper reinforcing roll chock 4-1, and the decrease bending bending force is applied to the lower work roll 1-2. The lower decrease bending apparatuses 7-3 and 7-4 that load the lower reinforcement roll chock 4-2 are incorporated.
For this reason, the reinforcing rolls 2-1 and 2-2 are also worn out by the rolling operation although not as much as the work rolls, and therefore it is necessary to periodically change the roll. Thus, in this rolling mill, the hydraulic piping of the decrease bending devices 7-1 to 7-4 has to be attached / detached every time the roll is changed, and there is a possibility that minute foreign matter will be mixed in the hydraulic piping at the time of attachment / detachment. Becomes higher. For this reason, it becomes difficult to employ a servo valve for high response hydraulic control in each of the decrease bending apparatuses 7-1 to 7-4. In addition, if it is necessary to connect to each hydraulic control valve via flexible piping such as flexible piping and detachable hydraulic piping in order to facilitate mounting and dismounting of the piping, fluctuations in hydraulic pressure are absorbed and mitigated because of the flexible structure. Sometimes it ends up.

Therefore, if flexible piping is used instead of servo valves for the hydraulic piping of the decrease bending devices 7-1 to 7-4 due to the ease of pipe attachment and detachment during roll replacement, the decrease bending device is The responsiveness is lower than the responsiveness of the increment bending apparatus.
For this reason, when a decrease bending force is applied as a work roll bending force for the purpose of plate crown and shape control, it is difficult to quickly change the setting during rolling. For this reason, appropriate roll bending control cannot be performed with respect to disturbance factors that change during rolling, such as the rolled material entry side plate thickness and the rolled material temperature, and the product quality and yield may be reduced.

On the other hand, the decrease bending force cannot be applied during idling when no rolling load is applied. When applying the decrease bending force, it is necessary to quickly switch from the roll balance state at the time of idling to the decrease bending force at the start of rolling and to quickly return to the roll balance state at the end of rolling.
Therefore, if the roll bending force is changed under the control of the decrease bending device having poor responsiveness, a predetermined defect bending force may not be applied to the leading end of the rolled material, and the shape defect portion may become long. .

Here, in the roll bending apparatus described in Patent Document 2, the responsiveness of the roll bending apparatus is determined by the secondary pipe length of the servo valve. In other words, the pipe length from each servo valve to the hydraulic cylinder is shortened to within 2m, and the difference between the oil pressure on the lease side and the oil pressure on the decrease side is controlled via the servo valve, resulting in high responsiveness of bending force. Can be secured. However, it is impractical to use fixed hydraulic piping on both the lease side and the decrease side because the work rolls and the reinforcement rolls must be reassembled regularly. For this reason, it is not possible to sufficiently increase the responsiveness when the decrease bending, which is the subject of the present invention, is applied.

The rolling method according to the present invention also solves the problem in Patent Document 2.
The increment bending apparatus means a hydraulic apparatus that applies a force in the direction of increasing the roll opening degree to the work roll chock. The increment bending apparatus is a general term for apparatuses including a hydraulic cylinder as an actuator. In the present invention, in order to simplify the description, the increment bending apparatus refers to a hydraulic cylinder that is an actuator thereof unless otherwise specified. A force applied to the work roll by the increase bending apparatus is referred to as an increase bending force. On the other hand, a hydraulic device that applies a force in the direction of decreasing the roll opening degree to the work roll chock is referred to as a decrease bending device, and a force applied to the work roll by this is referred to as a decrease bending force. The decrease bending apparatus is a general term for apparatuses including a hydraulic cylinder as an actuator. However, in the present invention, in order to simplify the description, the decrease bending apparatus refers to a hydraulic cylinder that is an actuator thereof unless otherwise specified.

FIG. 2 is a diagram showing an example of the operation flow of the rolling method according to the present invention. More specifically, FIG. 2 shows the operation of an increase bending device having a high responsiveness and a slightly bending responsive bending device. It is a figure which shows a flow.
FIG. 3 shows time-series changes in roll bending force and the like accompanying a rolling operation for a single rolled material when this rolling method is followed. FIG. 3 shows time-series changes in the rolling load, the output of the increment bending apparatus, the output of the decrease bending apparatus, and the work roll bending force as a resultant force from the top. Hereinafter, a description will be given with reference to FIGS.

First before the start of rolling, then performs the setting calculations corresponding to the rolling member rolling, which calculates and outputs the set value F _R of the work roll bending force. Here F _R is a negative value, that is, those which are calculated as decrease-bending force. In the present invention, the roll bending force is the increase bending force (the force in the increase direction (the direction in which the roll is opened)), and the decrease bending force (the force in the decrease direction (the direction in which the roll is pressed)). Is defined as a negative value.

Prior to the start of rolling, both the increase bending force and the decrease bending force are applied, and the roll bending force on the increase side corresponding to the roll balance force (F _B ) is applied to the work roll chock as a resultant force.
That is, at idle before rolling, the increment bending device output is I _B (> 0), the decrease bending device output is D _B (<0), and I _B + D _B is the roll balance force F _B (> 0). Works.
Incidentally, the roll balancing force F _B is rolls as a work roll and a driven which are driven by an electric motor in mill deceleration idling state is determined as a force that does not slip, also D _B working actuator of decrease-bending device What is necessary is just to set it with the minimum oil pressure that does not leave the roll chock.

And in a rolling immediately before the start timing (a point on the time axis), a sufficient predetermined rolling in decrease-bending device output D _S to exert the work roll bending force F _R during rolling D _{S =} F _R - computing the I _R. As the roll balancing force _{(F B)} is constant, at the same time outputs the _{D S} and _{I S.}
Here, I _R is-bending device output during rolling, is determined in advance to a value close to the minimum controllable value such that the absolute value of D _S is not excessive, I _S is I _{_S +} D _S = and F _B to become so-determined-bending device output.
Therefore, in the setting timing, the work roll bending force of the resultant force is substantially unchanged remains F _B.

Next, immediately after the start of rolling, the increase bending force is decreased while continuing the control to keep the constant bending force constant, so that the roll bending force on the predetermined decrease side acts on the work roll chock as a resultant force. Rolling.
That is, in the rolling start timing (b point on the time axis), is changed to I _R ink bending device output from the I _S. The control of the quick-bending apparatus responsive remains of such slow decrease-bending device output response by the D _S, the decrease-the work roll bending force of the resultant force from the roll balancing force F _{B (>} 0) can be quickly switched to-bending force _F R (<0).
Note that the rolling start time (b) refers to the time point when the rolling is started, and the detection thereof is, for example, the load detected by the load cell for measuring the rolling load of the rolling mill is the rolling load predicted and calculated in the setting calculation. For example, it may be determined by a method in which the timing exceeds 30%. This value is preferably set between 10 and 30%. This is because it can be distinguished from fluctuations in roll balance force, and the start of rolling can be detected quickly.

Then, at the end of rolling, the roll bending force is returned to the state before starting rolling, and the roll bending force on the increase side corresponding to the roll balance force is applied to the work roll chock as a resultant force, and the rolling of the metal plate material is finished in this state. To do.
That is, in the rolling end timing (c point on the time axis), decrease-bending device output returns the fast-bending device output response remains D _S from I _R to I _S. In this way, the work roll bending force as a resultant force can be quickly switched from the decrease bending force F _R (<0) to the roll balance force F _B (> 0).
The rolling end timing (point c on the time axis) refers to the end of rolling. The detection may be determined by a method in which the load detected by the load cell for measuring the rolling load of the rolling mill is set to a timing when the actual rolling load during rolling is less than 50% of a value obtained by time-series averaging, for example. This value can be set arbitrarily, but is preferably set between 50 and 80%. This is because it can be distinguished from fluctuations in roll bending force during rolling, and the end of rolling can be detected quickly.

Then a rolled end timing, for example, the time of the lapse of one to three seconds and work completion timing d, at this timing, the increase-bending device output I _B, the decrease-bending device output and D _B. This change work roll bending force of the resultant force is substantially maintained in the roll balancing force F _B.

As shown in FIGS. 2 and 3, in the rolling method according to the present invention, the roll bending force is changed at the start of rolling and at the end of rolling using a highly responsive increment bending apparatus provided in the project block. For this reason, even if it is unavoidable to deploy a decrease bending device that is less responsive than an increase bending device, a highly responsive increase bending device compensates for this. In addition, a powerful plate crown / shape control function can be provided.
Furthermore, even when the rolling force changes due to various factors (disturbances) during rolling, it is possible to quickly control to maintain the optimal work roll bending force with a highly responsive incremental bending device. It is.
That is, according to the rolling method of the present invention, it is possible to build a good plate crown and shape against disturbances that change during rolling, such as the rolled material entry side plate thickness and the rolled material temperature, and the product quality And the yield can be greatly improved.

FIG. 4 is a diagram showing time-series changes in roll bending force and the like when the response of the decrease bending apparatus is low (especially when the reaction force is reduced and the pressure drops when the reaction force is released). Similar to FIG. 3, a time-series change in roll bending force and the like accompanying a rolling operation on a single rolled material when the operation flow of the increment bending apparatus and the decrease bending apparatus shown in FIG. 2 is followed is shown. . That is, an example in which the response speed of the decrease bending apparatus is slower than in the case of FIGS.

When the response of the decrease bending apparatus is low as in this example, the increase bending apparatus having high response at the timings b and c changes abruptly, and the output of the decrease bending apparatus having poor response varies. . As a result, the work roll bending force as resultant force, delays to reach the timing b in F _R, it will be delayed possible to reach the timing c in F _B. The rolling method shown in FIG. 5 solves this problem.

FIG. 5 is a diagram showing another example of the operation flow of the rolling method according to the present invention, in which the operation of the incremental bending apparatus with high responsiveness and the decrease bending apparatus with low responsiveness compared to the case of FIGS. It is a figure which shows a flow. Hereinafter, a description will be given based on the drawing.
In the rolling method shown in FIG. 5, the increment bending apparatus based on the decrease bending force obtained by measuring the hydraulic pressure in the hydraulic pipe connected to the decrease bending apparatus or the decrease bending force measured by the load cell installed in the apparatus. To control. That is, before and after rolling, as the work roll bending force is roll balancing force F _B, as the work roll bending force for during rolling becomes F _R, the output of the increase-bending device, decrease-bending force or decrease- Control according to the hydraulic pressure of the leasing bending machine. The other control is the same as the rolling method shown in FIG.
By rolling with the rolling method shown in FIG. 5, as shown in FIG. 6, the increase bending device compensates for the fluctuation of the output of the decrease bending device, and the work roll bending force is realized with high response control. be able to.
In addition, it is possible to predict the fluctuation of the output of the decrease bending apparatus in advance and set the output of the increment bending apparatus to compensate for it without the need for measuring the bending bending force during rolling or feedback control by measuring the hydraulic pressure. In this way, the same effect can be obtained.

7 and 8 are side views showing another example of the structure of the rolling mill targeted by the present invention. These rolling mills can receive the rolling direction force applied to the body of the upper work roll 1-1 not by the project blocks 5-1 and 5-2 but by the housing window 12 so that the roll opening degree can be increased. It is an improvement.
Among these, the rolling mill shown in FIG. 7 is a rolling mill in which lower decrease bending apparatuses 7-3 and 7-4 for applying a decrease bending force to the lower work roll 1-2 are arranged in the lower reinforcing roll chock 4-2. . The rolling mill shown in FIG. 8 is a rolling machine in which the lower decrease bending apparatuses 7-3 and 7-4 are arranged in dedicated project blocks 5-3 and 5-4 located below the project blocks 5-1 and 5-2. Machine.
The rolling method according to the present invention can also be applied to these rolling mills, and this makes it possible to produce a good plate crown and shape against disturbances that change during rolling, such as the thickness of the rolled material entry side and the temperature of the rolled material. Product quality and yield can be greatly improved.

The present invention can be used for rolling a steel sheet, particularly a reverse rolling mill that requires a large opening.

1-1 Upper Work Roll 1-2 Lower Work Roll 2-1 Upper Reinforcement Roll 2-2 Lower Reinforcement Roll 3-1 Upper Work Roll Chock 3-2 Lower Work Roll Chock 4-1 Upper Reinforcement Roll Chock 4-2 Lower Reinforcement Roll Chock 5- 1 Incoming Project Block 5-2 Outgoing Project Block 5-3 Incoming Lower Project Block 5-4 Outgoing Lower Project Block 6-1 Incoming Upper Increase Bending Device 6-2 Outgoing Upper Increase Bending Device 6- 3 Incoming Lower Increase Bending Device 6-4 Outgoing Lower Increase Bending Device 7-1 Incoming Upper Decrease Bending Device 7-2 Outgoing Upper Decrease Bending Device 7-3 Incoming Lower Decrease Bending Device 7- 4 Outgoing lower decrease bending device 8-1 Entry-side reinforcing roll balance device -2 exit side rolls balancing device 9 housing 10 the material to be rolled 11 screw down device 12 housing window

Claims

A rolling mill having an increment bending device that generates an increase bending force and a decrease bending device that generates a decrease bending force is used, and the responsiveness of the decrease bending device is lower than that of the increase bending device. A method of rolling a metal sheet,
Before starting rolling, both the increase bending force and the decrease bending force are applied, and the roll bending force corresponding to the roll balance force is applied to the work roll chock as a resultant force.
Thereafter, at the start of rolling, the increase bending force is changed while maintaining the decrease bending force during the predetermined rolling, and the work roll bending force during the predetermined rolling is applied to the work roll chock as a resultant force.
During rolling, by controlling the increment bending force, the rolling is performed so as to maintain the work roll bending force during the predetermined rolling,
Then, at the end of rolling, change the increment bending force, and apply the roll bending force corresponding to the roll balance force to the work roll chock as a resultant force with the decrease bending force, and finish rolling the metal sheet in this state A method for rolling a metal sheet.
The rolling mill further includes a pair of upper and lower work rolls and a pair of upper and lower reinforcing rolls that respectively support them,
An increase hydraulic cylinder constituting the increase bending apparatus for each of the upper and lower work rolls is incorporated in a project block protruding inside the rolling mill housing, and a hydraulic pipe fixed to the hydraulic control valve of the increase hydraulic cylinder is provided. Having a connected structure,
Further, the decrease hydraulic cylinder constituting the decrease bending apparatus for the upper work roll is incorporated in the upper reinforcing roll chock, and a flexible and detachable hydraulic pipe is connected to the hydraulic control valve of the decrease hydraulic cylinder. The rolling method for a metal sheet according to claim 1, wherein the rolling is performed using the rolling mill.
Measure the hydraulic pressure in the decrease hydraulic cylinder or in the hydraulic piping connected to the cylinder, and control the increase bending force so that the roll bending force acting on the work roll chock becomes a predetermined value based on the measured value. The method for rolling a metal sheet according to claim 2.