JP2006181609A - Method for controlling rolling mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling a rolling mill by which the edge thickness of a rolled stock is surely made to coincide with the target value. <P>SOLUTION: A thickness meter 10A is installed on the downstream side of a rolling mill 4 and a plurality of thickness meters 10B are installed on the downstream side of the thickness meter 10A. After the tip T of the rolled stock 9 reaches the thickness meters 10B, a predicted sheet crown Cr is corrected by using a center thickness hc and edge thicknesses he actually measured with this thickness meters 10b. By predicting the edge thicknesses he from the predicted sheet crown Cr after correction and the center thickness hc measured with the thickness meter 10A, the rolling mill 4 is controlled so that the difference between the edge thicknesses he and the target edge thickness haim is minimized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control method for a rolling apparatus for rolling thick plates and the like.

Conventionally, when rolling a rolled material such as a thick plate, rough rolling is performed with a roughing mill based on a predetermined rolling pass schedule, and then finish rolling is performed with a finish rolling mill. In particular, in a finish rolling mill, a rolling load, a roll gap, and the like are appropriate because the thickness of the rolled material (particularly, the edge thickness that is the thickness of the end portion in the width direction of the rolled material) is set to a predetermined value. Control was done so.
Such control is disclosed in Patent Document 1, for example. The rolling apparatus of this technique includes a thickness gauge A for measuring a center plate thickness (plate thickness in the center in the width direction of the rolled material) in the vicinity of the downstream side of the rolling mill, and an edge plate thickness on the downstream side of the thickness gauge A. Are provided with a thickness gauge B for measuring the center plate thickness measured with the thickness gauge A and the edge plate measured with the thickness gauge B after the rolled material from the rolling mill reaches the thickness gauge B. The smaller plate thickness is selected by comparing with the thickness, and the roll gap of the rolling mill is adjusted with the selected plate thickness.
Japanese Patent No. 3542879 (FIG. 1)

However, in the technique described in Patent Document 1, the center plate thickness is measured by the plate thickness meter A, while the edge plate thickness is a plate thickness that is set apart on the downstream side of the plate thickness meter A. It is measured by the total B. That is, the edge plate thickness has “dead time” with respect to the center plate thickness.
Here, the dead time is a characteristic in which an output signal comes out with a delay of a certain time with respect to an input signal to a certain control target, and the waveform is kept as it is. A transfer function is e ^−Ls (L : Dead time), and it is necessary to consider the influence in the control.

In this way, when the edge plate thickness including the dead time is used as the control input value in the same row as the center plate thickness, not only accurate control cannot be performed, but the edge plate thickness of the rolled material matches the target value. May be difficult to do. In order to take into account the effect of dead time, even if the control function is applied and the transfer function e ^-Ls is applied to the edge plate thickness and ^used as a control input value, the actual rolling mill will accurately use the delay time L. The delay time is not constant for each pass.
Then, an object of this invention is to provide the control method of the rolling apparatus which can make the edge board thickness of a rolling material correspond with a target value reliably in view of the said problem.

In order to achieve the above object, the present invention takes the following technical means.
That is, technical means for solving the problems in the present invention include a rolling mill that rolls a rolled material, and a center plate thickness that is disposed on the downstream side of the rolling mill and that is the thickness of the center in the width direction of the rolled material. Thickness gauge A to be measured, and a plurality of thickness gauges B provided on the downstream side of the thickness gauge A to measure the center thickness and the edge thickness which is the thickness of the end in the width direction of the rolled material, In the control method of the rolling apparatus, after the tip of the rolled material reaches the plate thickness meter B, the predicted plate crown is corrected using the center plate thickness and the edge plate thickness actually measured by the plate thickness meter B, The edge plate thickness is predicted from the corrected predicted plate crown and the center plate thickness measured by the plate thickness meter A so that the difference between the predicted edge plate thickness and the target edge plate thickness is minimized. It is characterized by controlling the rolling mill.

The reason why it becomes possible to control the rolling apparatus with high accuracy by this technical means will be described below.
The prediction plate crown Cr for predicting the crown amount of the rolled material is a function of the rolling load P, the roll gap S of the rolling mill (gap between the work rolls 2 and 2), and the roll crown profile Φ (x) of the rolling roll. Can be represented. That is,

Cr = f (P, S, Φ (x)) (1)

It is.

Considering the input variables of equation (1), the rolling load P and the roll gap S of the rolling mill are values that can be measured by the rolling mill, and the roll crown profile Φ (x) is the shape of the rolling roll (x is the roll axis). It is self-evident that none of them is affected by the “dead time” due to the transport of the rolled material.
Therefore, as in the present technical means, the predicted sheet crown at the rolling mill exit side, that is, at the position of the thickness gauge A, is measured by the thickness gauge B located downstream of the thickness gauge A and having “dead time”. It is possible to make corrections based on the edge plate thickness, and this correction can make the predicted plate crown more accurate.

Furthermore, a high-precision rolling device is obtained by estimating the edge plate thickness (exit side edge plate thickness) at the position of the plate thickness meter A based on the corrected predicted plate crown and controlling the rolling mill with that value. You will be able to control.
Preferably, the plurality of thickness gauges B are composed of three thickness gauges arranged in a line in the sheet width direction of the rolled material, and one thickness gauge measures the center thickness, and the other 2 The two plate thickness gauges may measure the edge plate thickness on both sides in the width direction of the rolled material.
By doing so, it becomes possible to reliably obtain the actually measured plate crown at the position of the plate thickness meter B (plate thickness at the plate width center-plate thickness at the plate width end).

Further, when the tip of the rolled material exceeds the thickness gauge A and does not reach the thickness gauge B, the center thickness is measured by the thickness gauge A, and the measured center thickness and the predicted plate crown are measured. It is preferable to control the rolling mill so as to minimize the deviation between the predicted edge plate thickness and the target edge plate thickness.
By carrying out like this, in the situation where the front-end | tip part of a rolling material has reached the plate thickness meter A but it does not reach the plate thickness meter B, the exit side plate thickness of the rolled material can be controlled by the monitor AGC.
In order to accurately control the plate thickness of the rolled material, it is very preferable to apply the above technical means to the final rolling pass of the rolled material.

  By controlling the rolling device using this control method, it becomes possible to reliably match the edge plate thickness on the rolled material exit side with the target value.

Hereinafter, a control method of a rolling device according to the present invention will be described by illustrating reverse rolling of a thick steel plate.
The rolled material heated to a predetermined temperature in the heating furnace is reverse-rolled in accordance with a predetermined pass schedule in a rough rolling device, and then transferred to a finish rolling device installed downstream of the rough rolling device. Reverse rolling is applied.
In the finish rolling apparatus, the rolled material is finished into a product shape, that is, a predetermined width and plate thickness. Regarding the plate thickness, there are “center plate thickness” which is the plate thickness at the center in the width direction of the rolled material and “edge plate thickness” which is the plate thickness at both ends in the width direction. The thickness is defined as a value that matches the target value.

FIG. 1 shows an outline of a finish rolling device 1 (hereinafter referred to as a rolling device).
The rolling device 1 includes a rolling mill 4 including a pair of work rolls 2 and 2 and a pair of backup rolls 3 and 3. Above the upper backup roll 3 of the rolling mill 4, a hydraulic reduction device 5 that can adjust the roll gap S that is a gap between the work rolls 2 and 2, and a roll gap detector that measures the distance of the roll gap S 6. A rolling load detector 7 is provided. In addition, the rolling mill 4 is also provided with a rotation speed detector 8 for measuring the rotation speed of the work roll 2.

As shown in [Plan A] in FIG. 1, a thickness gauge 10 </ b> A for measuring the center plate thickness (exit-side center plate thickness) hc of the rolled material 9 on the exit side of the rolling mill 4 is provided on the rolling mill 4. On the downstream side, it is installed above the rolled material 9 and at the approximate center in the width direction. For convenience of explanation, the position where the thickness gauge 10A is installed is referred to as a line LA.
In addition, as shown in [Top view B] in FIG. 1, the three thickness gauges 10B are arranged on the downstream side of the thickness gauge 10A so as to be arranged substantially in a row above the rolled material 9 and in the width direction. ing. This position is referred to as a line LB for convenience of explanation. One of these three thickness gauges 10B is installed at the approximate center in the width direction of the rolled material 9, and the other two are installed at both ends of the rolled material 9, respectively. The center plate thickness hc is measured, and the edge plate thickness he is measured by the plate thickness gauges 10B and 10B on both sides in the width direction. These plate thickness gauges 10A and 10B are composed of gamma ray thickness gauges.

The data of the thickness gauges 10 </ b> A and 10 </ b> B described above are taken into the control means 12 via the thickness gauge controller 11. The control means 12 also receives data from the rotational speed detector 8 and adjusts the roll gap S of the rolling mill 4 based on these data.
In the control means 12, control is performed so as to control the gap of the rolling mill 4 so that the outlet edge plate thickness he of the rolling mill 4 matches the target edge plate thickness haim. That is, in the control method according to the present invention, after the tip T of the rolled material 9 reaches the plate thickness meter 10B, the predicted plate is obtained using the center plate thickness hc and the edge plate thickness he measured by the plate thickness meter 10B. The crown Cr is corrected, the edge plate thickness he is predicted from the corrected predicted plate crown Cr and the center plate thickness hc measured by the plate thickness meter 10A, and the predicted edge plate thickness he and the target edge The rolling mill 4 is controlled so that the difference from the plate thickness haim is minimized. Calculations necessary for such control are calculated by the process computer 13 connected to the control means 12.

Hereinafter, the details of the control method of the rolling apparatus 1 performed by the control means 12 and the process computer 13 will be described based on the flowchart of FIG.
This control method includes three methods when controlling the roll gap S of the rolling mill 4, and one of the three methods is selected depending on the location where the tip T of the rolled material 9 is located. It is like that.

First, consider a case where the rolled material 9 is being rolled and transferred from the upstream side to the downstream side of the rolling mill 4 and the tip T of the rolled material 9 has not reached the thickness gauge 10A.
The gap control in that case is as shown in FIG.
(i) The outlet side edge thickness he of the rolled material 9 is determined using the concept of the gauge meter AGC. Specifically, considering the elasticity (mill constant) of the rolling mill 4,
he = So + P / M (2)
Thus, the outlet edge plate thickness he is calculated. Here, the rolling load P, the mill constant M,
This is the roll gap initial value So.
(ii) Next, a deviation amount Δh between the obtained outlet edge plate thickness he and the target edge plate thickness haim is calculated. That is,
Δh = he−haim (3)
It is.
(iii) Therefore, the roll gap S is corrected so that the deviation amount Δh is 0 or the minimum. That is, based on the relationship of ΔS · M = Δh · (M + Q), the gap change amount ΔS such that Δh becomes 0 is
ΔS = −Δh · (M + Q) / M (4)
Therefore, the roll gap S is changed by ΔS obtained by this equation. Q is a plastic coefficient of the rolled material 9.

Next, a state where the tip T of the rolled material 9 is between the thickness gauge 10A and the thickness gauge 10B will be considered. At this time, since the tip T of the rolled material 9 does not reach the plate thickness meter 10B, the plate thickness by the plate thickness meter 10B cannot be obtained.
The gap control of the rolling mill 4 in this case is as shown in FIG.
(i) The center plate thickness (exit-side center plate thickness) hc at the line LA is measured by the plate thickness meter 10A.
(ii) Next, by applying the measured delivery center plate thickness hc to the predicted plate crown Cr, the edge plate thickness at the line LA, that is, the delivery side edge plate thickness he is predicted.
(iii) The amount of deviation Δh between the outlet edge thickness he and the target edge thickness haim thus determined is calculated.
(iv) The calculated deviation amount Δh is used, and the roll gap S of the rolling mill 4 is corrected so that the deviation amount ΔS becomes 0 or the minimum by using the equation (4) of the gauge meter. .
This method is called a monitor AGC.

Next, a state in which the tip T of the rolled material 9 has advanced beyond the thickness gauge 10B is considered.
The gap control of the rolling mill 4 in this case is as shown in FIG.
(i) The center plate thickness (exit-side center plate thickness) hc at the line LA is measured by the plate thickness meter 10A. In addition, the center plate thickness hc and the edge plate thickness he in the line LB are measured by the plate thickness meter 10B, and the measured plate crown is obtained.
(ii) The difference ΔCH between the calculated actual plate crown Cr ′ and the predicted plate crown Cr is calculated.
(iii) Based on the obtained difference ΔCH, the predicted plate crown Cr is corrected.
(iv) The edge plate thickness (exit side edge plate thickness) he at line LA is predicted using the corrected predicted plate crown Cr and the output side center plate thickness hc obtained by the plate thickness meter 10A.
(v) The amount of deviation Δh between the predicted outlet edge thickness he and the target edge thickness haim is calculated.
(vi) Using the gauge meter equation (4), the roll gap S of the rolling mill 4 is corrected so that the deviation amount ΔS becomes 0 or minimum using the calculated deviation amount Δh. To do.

The control method described above is calculated by the process computer 13, and the roll gap S of the rolling mill 4 is changed by the control means 12 via the hydraulic reduction device 5 based on the result.
Note that the predicted plate crown Cr described above can be expressed as a function of the rolling load P, the roll gap S of the rolling mill 4, and the roll crown profile Φ (x) of the rolling roll. That is,

Cr = f (P, S, Φ (x)) (1)

It is.

The rolling load P in the formula (1) and the roll gap S of the rolling mill 4 are values that can be measured by the rolling mill 4, and the roll crown profile Φ (x) is the shape of the rolling roll (x is the distance in the roll axis direction). It is self-evident that neither is affected by dead time. Therefore, it can be considered that the prediction plate crown itself is not affected by the dead time. Therefore, the predicted plate crown Cr corrected by the plate thickness meter 10B can be applied to the plate thickness meter 10A attached to the upstream side from the plate thickness meter 10B.
Various methods can be employed as the above-described “correcting the predicted plate crown Cr based on the obtained difference ΔCH”. For example, it is preferable to adopt the following method.

That is, the predicted plate crown Cr varies depending on the roll crown profile Φ (x) and is related as follows.
Cr = F (Φ (x)) (5)
The actual plate crown Cr ′ can be calculated as follows using the actual roll crown profile Φ ′ (x).
Cr ′ = F (Φ (x) + ΔΦ (x)) (6)
The function F (Φ (x)) of the equations (5) and (6) is defined as follows.
F (Φ (x)) = [α1 × [CWT (0) -CWT (x0)] + α2] (7)
F (Φ (x) + ΔΦ (x)) = [α1 × [CWT ′ (0) −CWT ′ (x0)] + α2] (7 ′)
However,
CWT (x): Predictive role profile
CWT '(x): Actual roll profile
x0: Coordinates of sheet thickness defining points α1, α2: Constants determined by the influence coefficient of roll profile on the amount of sheet crown, rolling size and rolling conditions.

When the difference ΔCH between the measured plate crown Cr ′ and the predicted plate crown Cr is expressed using the above formulas (5) to (7),
ΔCH = Cr'- Cr = F (Φ + ΔΦ) -F (Φ)
= [α1 × [CWT '(0) -CWT' (x0)] + α2]-[α1 × [CWT (0) -CWT (x0)] + α2]
= α1 × [CWT '(0) -CWT (0)]-[CWT' (x0) -CWT (x0)]
= α1 × [err (0)-err (x0)] (8)
However, err (x) = Φ (x) = CWT ′ (x) −CWT (x).

In the case of this embodiment,
err (x) = err0 × [1- (x / A) ² ], A is a constant (9)
Let's say. Then
err (0) -err (x0) = err0 × [1- (0 / A) ² ] -err0 × [1- (x0 / A) ² ] = err0 × (x0 / A) ²
Therefore, Equation (8) is
ΔCH = α1 × err0 × (x0 / A) ² (8 ')
It becomes.

From the equations (8 ′) and (9), the roll profile error ΔΦ, that is, err (x) is
ΔΦ (x) = err (x) = (ΔCH / [α1 × (x0 / A) ² ]) × [1- (x / A) ² ] (10)
It becomes. The predicted roll profile may be calculated using the roll profile error ΔΦ calculated by the equation (10), and the predicted plate crown Cr may be corrected based on the calculated predicted roll profile.
FIG. 3 shows an example of the result of rolling the rolled material 9 using the control method described above. In conventional rolling that does not use this control method, this control is compared with the deviation of the delivery edge thickness he (measured value of delivery edge thickness-target edge thickness) of about 0.08 mm. In the rolling using the method, the deviation was 0.065 mm or less.
As can be seen from this, by using this control method, the edge plate thickness on the rolling mill exit side can be surely matched with the target value.

The present invention is not limited to the above embodiment.
That is, the rolling device 1 of the present embodiment includes the thickness gauges 10A and 10B on the downstream side of the rolling mill 4 and controls the rolling mill 4 based on the data, but on the upstream side of the rolling mill 4. Also, the thickness gauges 10A and 10B may be installed. By doing so, in the reverse rolling in the rolling mill 4, this control method can be applied not only in the upstream → downstream rolling but also in the downstream → upstream rolling.

  Moreover, although this embodiment illustrated and demonstrated the control method of the rolling apparatus in the finish rolling mill 4, you may employ | adopt the said control method to a rough rolling apparatus. There is no problem even if it is adopted in both the rough rolling device and the finish rolling device.

It is the schematic of a rolling apparatus. It is a flowchart of this control means. It is the figure which showed the result of having rolled using this control method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling device 2 Work roll 3 Backup roll 4 Rolling machine 5 Hydraulic reduction device 6 Roll gap detector 7 Rolling load detector 8 Rotational speed detector 9 Rolled material 10A Thickness gauge A
10B Thickness gauge B
11 Plate thickness controller 12 Control means 13 Process computer

Claims (4)

A rolling mill that rolls the rolled material, a sheet thickness meter A that is disposed on the downstream side of the rolling mill and measures a center plate thickness that is a thickness in the center in the width direction of the rolled material, and downstream of the thickness meter A In the control method of the rolling apparatus having a plurality of thickness gauges B that are provided on the side and measure the edge plate thickness, which is the plate thickness of the center plate thickness and the end portion in the width direction of the rolled material,
After the tip of the rolled material reaches the plate thickness meter B, the predicted plate crown is corrected using the center plate thickness and the edge plate thickness actually measured by the plate thickness meter B, and the corrected predicted plate crown and the An edge plate thickness is predicted from the center plate thickness measured by the plate thickness meter A, and the rolling mill is controlled so that the difference between the predicted edge plate thickness and the target edge plate thickness is minimized. A control method of the rolling apparatus.   When the tip of the rolled material exceeds the thickness gauge A and does not reach the thickness gauge B, the center thickness is measured by the thickness gauge A, and the measured center thickness and the predicted sheet crown are used. 2. The rolling mill control according to claim 1, wherein the edge plate thickness is predicted to control the rolling mill so that a deviation between the predicted edge plate thickness and the target edge plate thickness is minimized. Method.   The plurality of thickness gauges B are composed of three thickness gauges arranged in a line in the sheet width direction of the rolled material, one thickness gauge measures the center thickness, and the other two thickness gauges are rolled. The method for controlling a rolling apparatus according to claim 1 or 2, wherein edge plate thicknesses on both sides in the width direction of the material are respectively measured.   A control method for a rolling apparatus, wherein the control method according to any one of claims 1 to 3 is applied to a final rolling pass of a rolled material.

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