JP2003112213A - Controller, controlling method, computer program and computer readable recording medium for rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform appropriate control to an arbitrary material to be rolled in the case that tension control is performed by reduction. SOLUTION: In the reduction command value calculating part 8a of a tension controller 8, a reduction command value to an (i+1) stand 3 for making the unit tension deviation of a steel sheet 1 between stands 2, 3 as substantially zero is calculated by using a transfer function by P control, PI control or PID control and the reduction command value is sent out to the reduction mechanism 6 of the (i+1) stand 3. In such a case, in the control gain changing part 8b of the tension controller 8, the control gain (proportional gain, integral gain or the like) in the P control, PI control or PID control of the transfer function used in the reduction command value calculating part 8a is changed in accordance with the width of the steel sheet 1 between the stands 2, 3 which is measured with width measuring apparatus 9 and the threading speed of the steel sheet 1 which is passed through the (i+1) stand 3 which is measured with a threading speed measuring apparatus 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling mill control apparatus and method suitable for controlling tension by rolling when rolling a steel sheet or the like by a tandem rolling mill equipped with a plurality of stands. , A computer program, and a computer-readable recording medium.

[0002]

2. Description of the Related Art Sheet thickness is one of the evaluation criteria for products in hot rolling and cold rolling of steel products, and automatic gauge control (AGC) is performed in a rolling mill. The applicant of the present application has filed Japanese Patent Application Laid-Open No. 4-3
No. 61809, Japanese Unexamined Patent Publication No. 5-261418, Japanese Unexamined Patent Publication No. 2000-33410 and the like disclose tension control by rolling down.

The basic principle of tension control by rolling will be described. Disturbances that cause the deviation of the strip thickness in the hot rolling process include skid mark disturbances and roll eccentricity disturbances. Skid mark disturbance is a disturbance caused by temperature unevenness in the longitudinal direction of the material to be rolled due to the skid on which the material to be rolled is placed, and even if the material to be rolled has no plate thickness deviation, the deformation resistance due to high or low temperature Fluctuates and becomes a factor of deviation of the plate thickness on the output side. Further, the roll eccentric disturbance is a disturbance caused by the roll moving up and down due to the deviation between the geometric center and the mass center of the backup roll in contact with the work roll, and the roll gap (rolling position) fluctuating. .

As a physical quantity for detecting the influence of the skid mark disturbance and roll eccentricity disturbance on the outgoing side plate thickness, attention is paid to the unit tension of the material to be rolled between the stands, and the tension control by the rolling reduction is performed, whereby the skid mark disturbance is controlled. Also, the deviation of the outlet plate thickness caused by the roll eccentricity disturbance is suppressed.

Now, in the i + 1 stand, when the entrance side plate thickness H (i + 1) and the exit side velocity v (i + 1) are constant, the output side plate thickness h (i + 1) is targeted by the influence of skid mark disturbance or roll eccentricity disturbance. Departure-side plate thickness deviation Δ from the value h ₀ (i + 1)
Suppose that h (i + 1) has occurred.

In any case, the volume entering and leaving the i + 1 stand in the unit time is the same, so the following equation (1) is established. h (i + 1) ・ v (i + 1) ・ b (i + 1) = H (i + 1) ・ V (i + 1) ・ B (i + 1) (1) However, h (i + 1): i + 1 stand exit side plate thickness [mm] v (i + 1): i + 1 stand exit side speed [mm / s] b (i + 1): i + 1 stand exit side plate width [mm] H (i + 1): i + 1 stand entrance plate thickness [mm] V (i + 1): i + 1 stand entrance side Velocity [mm / s] B (i + 1): i + 1 Stand entrance side plate width [mm]

When the plate width does not fluctuate, B (i
Since +1) = b (i + 1) is established, the following equation (2) is introduced, and the outlet side plate thickness deviation Δh (i + 1) corresponds to the i + 1 stand entrance side velocity V (i + 1). h (i + 1) · v (i + 1) = H (i + 1) · V (i + 1) (2)

Further, the unit tension T (i) of the material to be rolled between the stands is expressed by the following equation (3) by using the i + 1 stand entry side velocity V (i + 1) and the i stand exit side velocity v (i). As described above, the amount is determined by the integral of the difference (the sum within the time during which the material to be rolled passes between the stands). Therefore, i +
When the velocity V (i + 1) on one stand entry side fluctuates, the unit tension T (i) of the material to be rolled between the stands changes. T (i) = (E / L) ∫ {V (i + 1) -v (i)} dt (3) However, E: Young's modulus [kgf / mm ² ] L: Distance between stands [mm]

From the above, if the influence of the looper between stands is not considered, the deviation of the outlet plate thickness Δh (i + 1) due to the influence of skid mark disturbance or roll eccentric disturbance.
And the unit tension deviation ΔT (i) of the material to be rolled between the stands have a one-to-one correspondence. That is, operating the reduction position to keep the tension constant eliminates the plate pressure deviation Δh (i + 1). Further, even if the delivery side plate thickness deviation Δh (i + 1) is generated just below the roll bite due to the fluctuation of the oil film thickness of the i + 1 stand and the influence of the roll expansion coefficient, it is completely removed by the same principle.

[0010]

When performing the tension control by the above-described reduction, it is necessary to accurately grasp and control the influence coefficient as to how the tension changes when the reduction is operated. If the same parameters are used for any rolled material without capturing such influence coefficient,
Even if appropriate control is performed on a certain material to be rolled, there is a possibility that appropriate control is not performed on other material to be rolled.

The present invention has been made in view of the above points, and it is an object of the present invention to make it possible to appropriately control an arbitrary material to be rolled when tension control by rolling is performed. To aim.

[0012]

The control device for a rolling mill according to the present invention uses the above i + 1 stand in order to make the unit tension deviation of the material to be rolled between the i stand and the i + 1 stand of the tandem rolling mill substantially zero. A rolling mill controller for controlling the rolling position of the rolling mill, and a rolling reduction command value calculating unit for calculating a rolling reduction command value for the i + 1 stand for making the unit tension deviation of the material to be rolled between the stands substantially zero. And a parameter changing unit that changes a parameter in the calculation process in the reduction command value calculation unit according to at least one of the strip width of the rolled material between the stands and the strip passing speed in the i + 1 stand. It is characterized in that it is equipped.

The control device for another rolling mill according to the present invention is
In order to make the unit tension deviation of the rolled material between the i stand and the i + 1 stand of the tandem rolling mill substantially zero, the above i
A controller of a rolling mill for controlling a rolling position of a +1 stand, wherein a rolling command value is calculated for calculating a rolling command value for the i + 1 stand for making a unit tension deviation of a material to be rolled between the stands substantially zero. Section, the plate width of the rolled material between the stands, and a parameter for changing the parameter in the calculation process in the reduction command value calculation unit according to at least one of the plate thickness of the rolled material between the stands It is characterized in that it includes a changing unit.

In the rolling mill control method of the present invention, the rolling position of the i + 1 stand is controlled so that the unit tension deviation of the material to be rolled between the i stand and the i + 1 stand of the tandem rolling mill is substantially zero. A method of controlling a rolling mill, comprising: a procedure for calculating a rolling-down command value for the i + 1 stand for making the unit tension deviation of the rolled material between the stands substantially zero; and a plate of the rolled material between the stands. Width and
It is characterized in that it has a procedure of changing the parameter in the above-mentioned calculation procedure according to at least one of the strip passing speeds at the i + 1 stand.

Further, another method of controlling a rolling mill according to the present invention is
In order to make the unit tension deviation of the rolled material between the i stand and the i + 1 stand of the tandem rolling mill substantially zero, the above i
A method of controlling a rolling mill for controlling a rolling position of a +1 stand, comprising the steps of calculating a rolling command value for the i + 1 stand for making a unit tension deviation of a material to be rolled between the stands substantially zero, It is characterized in that it has a plate width of the rolled material between the stands and a procedure for changing the parameters in the calculation procedure according to at least one of the plate thickness of the rolled material between the stands.

The computer program of the present invention sets the above i + 1 to make the unit tension deviation of the rolled material between the i stand and the i + 1 stand of the tandem rolling mill substantially zero.
A computer program for controlling the rolling position of a stand, the process of calculating a rolling command value for the i + 1 stand for making the unit tension deviation of the material to be rolled between the stands substantially zero; The process for changing the parameter in the calculation process according to at least one of the strip width of the rolled material and the strip passing speed at the i + 1 stand is characterized by being performed.

Another computer program of the present invention controls the rolling position of the i + 1 stand so that the unit tension deviation of the material to be rolled between the i stand and the i + 1 stand of the tandem rolling mill is substantially zero. And a process for calculating a reduction command value for the i + 1 stand to make the unit tension deviation of the rolled material between the stands substantially zero, and a plate of the rolled material between the stands. It is characterized in that processing for changing the parameter in the calculation processing is executed according to at least one of the width and the plate thickness of the rolled material between the stands.

The computer-readable recording medium of the present invention is characterized in that the computer program is stored.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a rolling mill control device, method, computer program, and computer-readable recording medium according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration for controlling the rolling mill in the present embodiment. Here, a tandem rolling mill in the hot rolling process will be described. Normally, a tandem rolling mill has 6 to 7 stands, but only i stand and i + 1 stand are shown in FIG. 1 (i = 1.
~ N).

In the figure, 1 is a steel plate which is a material to be rolled. 2 is an i stand, 3 is an i + 1 stand, and these stands 2, 3 are a rolling roll 5 composed of a backup roll and a work roll, and a rolling roll 5 for applying a rolling pressure necessary to obtain a predetermined plate thickness. And a device 6.

Reference numeral 4 is a looper for controlling the mass flow between the stands 2 and 3. 7 stands 2
It is a tension measuring device which measures the unit tension of the steel plate 1 between.
Reference numeral 9 is a plate width measuring device for measuring the plate width of the steel plate 1 between the stands 2 and 3. Reference numeral 10 is a strip running speed measuring device for measuring the strip running speed of the steel plate 1 passing through the i + 1 stand 3.

Numeral 8 is a tension control device, which is based on the unit tension of the steel plate 1 between the stands 2 and 3 measured by the tension measuring device 7 through the rolling down device 6 and the i + 1 stand 3
The tension of the steel plate 1 is controlled by controlling the rolling position of the roll.

In the rolling reduction command value calculation section 8a of the tension control device 8, the rolling reduction command value for the i + 1 stand 3 for making the unit tension deviation of the steel plate 1 between the stands 2 and 3 substantially zero is P control or PI control. Alternatively, it is calculated using the transfer function by PID control, and the reduction command value is sent to the reduction device 6 of the i + 1 stand 3.

Further, in the control gain changing section 8b of the tension control device 8, the plate width of the steel plate 1 between the stands 2 and 3 measured by the plate width measuring device 9 and the plate passing speed measuring device 10 are measured.
According to the stripping speed of the steel sheet 1 passing through the i + 1 stand 3 measured by, the parameter in the calculation process in the reduction command value calculation unit 8a, specifically, the parameter used in the reduction command value calculation unit 8a. The control gain (proportional gain, P gain) in P control or PI control or PID control of the transfer function
Change the integral gain, etc.).

Next, the operation in the case of performing the tension control by rolling down will be described. As shown in FIG. 1, the steel sheet 1 is sequentially rolled by the i stand 2 and the i + 1 stand 3.

In the tension control device 8, for example, the representative value (or moving average value) of the actual unit tension values of the steel sheet 1 between the stands 2 and 3 measured after the start of rolling is used as the unit between the stands 2 and 3. Set the target tension value T _aim .

After that, in the tension controller 8, the actual unit tension value T (i) of the steel plate 1 between the stands 2 and 3 is measured, and the unit tension deviation ΔT (i) with respect to the target value T _aim is substantially zero. Command value ΔS of the i + 1 stand 3 for
_{Ref (i + 1)} is calculated by the following equation (4). ΔS _{Ref (i + 1)} = F (ΔT (i)) (4)

Then, the calculated rolling reduction command value ΔS
_{The rolling down} device 6 of the i + 1 stand 3 is controlled based on _{Ref (i + 1)} . As described above, if the influence of the looper 4 between the stands 2 and 3 is not considered, the deviation of the outgoing plate thickness Δh due to the influence of the skid mark disturbance or the roll eccentric disturbance.
Unit tension deviation Δ of steel plate 1 between (i + 1) and stands 2 and 3
Since there is a one-to-one correspondence with T (i), the unit tension deviation ΔT
(i) The reduction command value ΔS _{Ref (i + 1)} of the i + 1 stand 3 for making it substantially zero is calculated, and the reduction command value ΔS _Re is calculated.
By controlling the rolling down device 6 of the i + 1 stand 3 based on _{f (i + 1)} , it is possible to remove the outlet side plate pressure deviation Δh (i + 1).

As a result of diligent research conducted by the present inventors in the tension control by means of the rolling reduction as described above, the influence coefficient as to how the tension fluctuates when the rolling reduction is operated is determined by the passing speed and the strip width. It came to the technical idea that it fluctuated due to.

In adjusting the tension control system by rolling down,
It is important to accurately understand the "transfer function from the rolling command to the rear tension (unit tension deviation between stands)". The inventors have determined a backward tension Δσ _(i) (= unit tension deviation ΔT (i) of the steel plate 1 between the stands 2 and 3 ₎ from the reduction command value ΔS _{Ref (i + 1)} to the reduction device 6 of the i + 1 stand 3. The transfer function (open loop) to is expressed by the following equations (5) to (7).
I got the recognition that it is described in. In FIG. 2, there is a feedback section for the unit tension fluctuation amount to the reverse rate fluctuation amount, but this is not artificial feedback, and should be mitigated when the unit tension between stands fluctuates. It is a natural phenomenon that causes the reverse rate to change, and is hereinafter referred to as a "natural phenomenon of reverse rate fluctuation based on unit tension fluctuation".

[0032]

[Equation 1]

The following symbols are used, and the deviation means the deviation from the reference value. ΔS _{Ref (i + 1)} : Reduction command value to i stand [mm] ΔS _(i) : i stand reduction position deviation [mm] Δσ _(i) : Unit tension deviation between stands [kgf / mm ² ] ΔV _{n ( i)} : Deviation of the neutral point speed (passing speed) of the i stand [m
m / s] ΔH _(i) : i-stand entrance side plate thickness deviation [mm] Δh _(i) : i-stand exit side plate thickness deviation [mm] ΔB _(i) : i-stand entrance side plate width deviation [mm] Δb _(i) : I stand stand-out side plate width deviation [mm] f _(i) : i stand advanced rate [no unit] β _(i) : i stand reverse rate [no unit] ω _(i) : i stand compression system resonance frequency [rad / s] η _(i) : i stand rolling-down damping coefficient [no unit] Q _(i) : i stand plasticity coefficient [Ton / mm] (1 [T
on] = 1000 [kgf] M _(i) : i stand mill rigidity coefficient [Ton / mm] (1
[Ton] = 1000 [kgf] K _{1 (i)} : i stand coefficient K _{2 (i)} : i stand coefficient ∂f _(i) / ∂h _(i) : f _(i) when f _{( i)} is changed. influence coefficient ∂f representing the momentum of _{i) (i) / ∂σ (} i): σ ( influence coefficients representing the momentum of f when the _i) was varied _{(i) ∂h (i) /} ∂σ (i _): sigma _(i) influence coefficient representing the momentum of f _(i) in the case of varying the _{∂b (i) / ∂σ (i} ): the influence of sigma _(sigma when the _i) was varied _(i) Coefficient E _(i) : Young's modulus [kgf / mm ² ] L _(i) : Distance between stands [mm]

Here, as a transfer function from the reduction command value ΔS _{Ref (i + 1)} to the reduction device 6 of the i + 1 stand 3 to the rear tension (unit tension deviation between stands) Δσ _(i) , the above equations (5) to (5) The point where (7) is derived will be described. Note that the secondary system part of the above equation (1) shows the response of the drive system (mill motor part), and the primary system part relates to the plate speed between the outlet side and the inlet side of the adjacent stands. It is derived based on the mechanism by which unit tension is generated by "integration of speed difference (see the above equation (3))". Therefore, the essential part of the primary system will be described below.

Considering a system for controlling the reduction command value ΔS _{Ref (i + 1)} to the reduction device 6 of the i + 1 stand 3 to the rear tension (= unit tension deviation between stands) Δσ _(i) , the block shown in FIG. Expressed as a diagram. It should be noted that the feedback portion in the block diagram of FIG. 2 is a loop existing in the natural phenomenon world and can be said to be an open loop, not an artificial addition.

In summary, the reduction command value ΔS
_{When Ref (i + 1)} is operated, fluctuation Δh _{(i + 1)} occurs in the plate thickness,
As a result, the forward rate f _{(i + 1)} and the reverse rate β _{(i + 1 )} of the i + 1 stand 3 fluctuate, and as a result, the entrance speed of the i + 1 stand 3 fluctuates. The unit tension deviation Δσ _{(i) of the} steel plate 1 changes. In addition, the steel plate 1 expands and contracts in a direction to suppress the fluctuation of the unit tension, thereby changing the reverse speed. This is the mechanism of the above-mentioned "natural phenomenon of reverse rate fluctuation based on unit tension fluctuation".

First, the variation Δh _{(i + 1)} of the plate thickness when the reduction command value ΔS _{Ref (i + 1)} is manipulated will be described. The plasticity coefficient Q _{(i + 1)} (plate width When the i stand mill stiffness coefficient M _(i) is given, the following equation (8)
The relationship shown in is established (see block 101 in FIG. 2). Δh _{(i + 1)} = ΔS _{Ref (i + 1)} · {M _{(i + 1)} / (M _{(i + 1)} + Q _{(i + 1)} )} (8)

Next, the fluctuation β _{(i + 1)} of the backward movement rate with respect to the fluctuation Δh _{(i + 1)} of the plate thickness will be described. The relationship shown is established (see block 102 in FIG. 2). Δβ _{(i + 1)} = {∂β _{(i + 1)} / ∂h _{(i + 1)} } · Δh _{(i + 1)}・ ・ ・ (9)

Explaining the variation β _{(i + 1)} of the backward movement rate with respect to the variation ΔΣ _(i) of the unit tension, the relationship shown in the following equation (10) is obtained by the predetermined influence coefficient that is not influenced by the strip width. Is true (see block 103 in FIG. 2). Δβ _{(i + 1)} = {∂β _{(i + 1)} / ∂σ _(i) } ・ Δσ _(i)・ ・ ・ (10)

Since the growth changes depending on the total (subtraction) of the fluctuations in the reverse speed, the relationship shown in the following equation (11) is established (see block 104 in FIG. 2). V _{R (i + 1)} is the roll peripheral speed. The final elongation (hereinafter referred to as “elongation”) that is input to the block 104 in FIG. 2 is: elongation = {(∂β _{(i + 1)} / ∂h _{(i + 1)} ) · Δh _{(i + 1 )} − (∂β _{(i + 1)} / ∂σ _(i) ) · Δσ _(i) } · VR _{(i + 1)} ... (11).

The integral of the above "stretch" is calculated by the distance L between stands.
divided by _(i), the multiplied by Young's modulus E _(i) (see block 105 of FIG. 2), the unit tension deviation .DELTA..sigma _(i).

From the block diagram (see FIG. 2) obtained as described above, the transfer function is described by the above equations (5) to (7).

Now, in the above equations (5) to (7), K _{1 (i)} ∝ V _{n (i + 1)} ... (12) K _{2 (i)} ∝ V _{n (i + 1).} (13) K _{2 (i)} ∝ M _{(i + 1)} / (M _{(i + 1)} + Q _{(i + 1)} ) (14) The pole (K _{1 (i)} ) of the transfer function is dominated by the strip running speed (V _{n (i + 1)} ), and (2). The direct-current gain (K _{2 (i)} / K _{1 (i)} ) of the transfer function is the strip speed (V _{n (i + 1)} )
Then, it can be seen that there is a possibility that the plasticity coefficient (Q _{(i + 1)} ) is dominated. In this case, when the Bode diagram is considered for the transfer function, the outline is as shown in FIG.

Here, in FIG. 4A, the strip passing speed V
_{n (i + 1)}The pole K of the transfer function with the change of_{1 (i)}Shows the change of.
As can be seen from the figure, the pole K of the transfer function_{1 (i)}Through
Plate speed V _{n (i + 1)}Is changing in response to changes in. Meanwhile, the figure
As shown in FIG. 4 (B), the pole K of the transfer function_{1 (i)}Is the width change
It is almost constant regardless of. From this data,
Regarding the characteristics of the transfer function from the reduction command to the rear tension,
Pole of reaching function K_{1 (i)}Is the passing speed V_{n (i + 1)}Controlled by
Was confirmed.

FIG. 5 shows the relationship between the plasticity coefficient Q _{(i + 1)} and the plate width B _{(i + 1)} of the steel plate 1 between the stands 2 and 3.
As shown in the figure, the plasticity coefficient Q _{(i + 1)} and the stands 2, 3
It is confirmed that there is a substantially proportional relationship with the plate width B _{(i + 1)} of the steel plate 1 between them. That is, the direct-current gain (K _{2 (i)} / K _{1 (i)} ) of the transfer function is the strip running speed (V _{n (i + 1)} ) and the plasticity coefficient (Q _{(i + 1)} ). , The width of the steel plate 1 between the stands 2 and 3 (B _{(i + 1)} ).

Then, FIG. 6B shows a change in the DC gain K _{2 (i)} / K _{1 (i)} of the transfer function with a change in the plate width B _{(i + 1)} . As can be understood from the figure, the DC gain K _{2 (i)} / K _{1 (i)} of the transfer function changes according to the change of the strip width B _{(i + 1)} . On the other hand, as shown in FIG. 6 (A), the DC gain K _{2 (i)} / K _{1 (i)} of the transfer function is almost constant regardless of the change in strip passing speed. From this data as well, regarding the characteristics of the transfer function from the reduction command to the rear tension, the DC gain (K _{2 (i)} / K _{1 (i)} ) of the transfer function is i stand and i + 1.
It was confirmed that the width of the steel plate between the stands (B _{(i + 1)} ) was controlled.

Summarizing the above results, the coefficient of influence as to how the tension fluctuates when the rolling operation is carried out fluctuates depending on the plate width and the plate passing speed. Therefore, depending on the strip width and the strip passing speed, the parameters in the calculation process in the reduction command value calculation unit 8a, specifically, the P control or PI of the transfer function used in the reduction command value calculation unit 8a.
By changing the control gain (proportional gain, integral gain, etc.) in the control or PID control, for example, appropriate control can be performed on wide and narrow steel plates and steel plates with slow and fast strip passing speeds. it can.

When the control gain is changed, the control gains of the plate width and the plate passing speed which are the reference are determined in advance, and the control gain is increased or decreased according to the plate width and the plate passing speed from the reference. Alternatively, the control gains corresponding to a plurality of strip widths and strip passing speeds may be tabulated in advance and the control gains may be changed according to the strip width and strip passing speeds.

Further, in the above-mentioned embodiment, the strip speed is measured by the strip speed measuring device 10 for measuring the strip speed of the steel plate 1. However, in practice, the FSU is just before the finish rolling mill biting. Since it is first calculated and determined by software on the computer called (Finisher Set Up), there is a problem that it is slow to change the control gain after obtaining the strip speed.

Therefore, there is a correlation between the strip running speed and the final stand exit side plate thickness.
Paying attention to the tendency that the thicker the steel plate is, the slower the strip running speed is, and the control gain may be changed according to the final stand outgoing side plate thickness instead of the strip running speed.

(Other Embodiments) In order to operate various devices so as to realize the functions of the above-described embodiments, a computer in an apparatus or system connected to the various devices is operated in the above-described embodiment. The present invention also includes a computer program for realizing the functions of the above, which is executed by operating the above various devices according to the program stored in the computer (CPU or MPU) of the system or apparatus. .

Further, in this case, the computer program itself realizes the functions of the above-described embodiments, and constitutes the present invention. As a transmission medium of the computer program, a computer network (L) for propagating and supplying program information as a carrier wave is supplied.
A communication medium (a wired line such as an optical fiber or a wireless line) in a system such as an AN, a WAN such as the Internet, a wireless communication network, or the like can be used.

Further, means for supplying the computer program to the computer, for example, a recording medium storing the computer program constitutes the present invention. Examples of such recording media include flexible disks, hard disks, optical disks, magneto-optical disks,
CD-ROM, magnetic tape, non-volatile memory card,
ROM or the like can be used.

[0054]

As described above, according to the present invention, when tension control by rolling is performed, an arbitrary rolled material (wide,
Appropriate control can be performed for a narrow steel plate and a steel plate having a low or high sheet passing speed. Therefore, stable rolling performance can be obtained and yield can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration for controlling a rolling mill in the present embodiment.

FIG. 2 is a block diagram showing a system of control from a reduction command value to rearward tension.

FIG. 3 is a diagram showing an outline of a transfer function from a reduction command value to a rear tension.

FIG. 4 is a diagram showing a change in a pole [rad / s] of a transfer function with a change in a strip passing speed [mpm] and a change in a strip width [mm].

FIG. 5 is a diagram showing a relationship between a plasticity coefficient [Ton / mm] and a plate width [mm] of a steel plate between stands.

FIG. 6 is a diagram showing a change in DC gain of a transfer function due to a change in strip passing speed and a change in strip width.

[Explanation of symbols]

1 steel plate 2 i stand 3 i + 1 stand 4 Looper 5 Rolling roller 6 Rolling down device 7 Tension measuring device 8 Tension control device 8a Reduction command value calculation unit 8b Control gain change unit 9 Board width measuring device 10 Strip speed measuring device

Claims (7)

[Claims] 1. A rolling mill controller for controlling the rolling position of the i + 1 stand so that the unit tension deviation of the rolled material between the i stand and the i + 1 stand of the tandem rolling mill is substantially zero. A rolling reduction command value calculation unit for calculating a rolling reduction command value for the i + 1 stand for making the unit tension deviation of the rolling material between the stands substantially zero, a strip width of the rolling material between the stands, and A controller for a rolling mill, comprising: a parameter changing unit that changes a parameter in a calculation process in the reduction command value calculation unit according to at least one of the strip passing speeds at the i + 1 stand. 2. A rolling mill controller for controlling the rolling position of the i + 1 stand so that the unit tension deviation of the material to be rolled between the i stand and the i + 1 stand of the tandem rolling mill is substantially zero. A rolling reduction command value calculation unit for calculating a rolling reduction command value for the i + 1 stand for making the unit tension deviation of the rolling material between the stands substantially zero, a strip width of the rolling material between the stands, and A controller for a rolling mill, comprising: a parameter changing unit that changes a parameter in a calculation process in the reduction command value calculation unit according to at least one of the plate thicknesses of rolled materials between the stands. . 3. A rolling mill control method for controlling the rolling position of the i + 1 stand so that the unit tension deviation of the material to be rolled between the i stand and the i + 1 stand of the tandem rolling mill is substantially zero. , A procedure for calculating a rolling reduction command value for the i + 1 stand for making the unit tension deviation of the rolled material between the stands substantially zero, a plate width of the rolled material between the stands, and the i + 1 stand And a procedure for changing a parameter in the calculation procedure according to at least one of the strip passing speeds. 4. A rolling mill control method for controlling the rolling position of the i + 1 stand so that the unit tension deviation of the material to be rolled between the i stand and the i + 1 stand of the tandem rolling mill is substantially zero. A procedure for calculating a reduction command value for the i + 1 stand for making the unit tension deviation of the rolled material between the stands substantially zero, a plate width of the rolled material between the stands, and a distance between the stands And a procedure for changing the parameters in the above-described calculation procedure according to at least one of the plate thicknesses of the material to be rolled. 5. A computer program for controlling the rolling position of the i + 1 stand so that the unit tension deviation of the material to be rolled between the i stand and the i + 1 stand of the tandem rolling mill is substantially zero. A process of calculating a reduction command value for the i + 1 stand for making the unit tension deviation of the rolled material between the stands substantially zero, a plate width of the rolled material between the stands, and a process in the i + 1 stand A computer program that executes a process of changing a parameter in the calculation process according to at least one of the strip passing speeds. 6. A computer program for controlling the rolling position of the i + 1 stand to make the unit tension deviation of the material to be rolled between the i stand and the i + 1 stand of the tandem rolling mill substantially zero. A process of calculating a reduction command value for the i + 1 stand for making the unit tension deviation of the rolled material between the stands substantially zero; a plate width of the rolled material between the stands; A computer program for executing a process of changing a parameter in the calculation process according to at least one of the plate thicknesses of rolled materials. 7. A computer-readable recording medium having the computer program according to claim 5 or 6 stored therein.