JP2004025271A - Method for controlling edge drop in tandem cold rolling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the accuracy of a strip thickness in the thickness direction of a strip and to make a yield higher by controlling edge drop with good accuracy. <P>SOLUTION: A model equation having constants that are learning items separately on a work side and a drive side is previously formed as a model equation which predicts the amount of the edge drop on the outlet side of a tandem rolling mill and which includes the amount of the edge drop and the amount of work roll shift of the strip to be rolled as parameters. The learning items are updated separately on the work side and the drive side in such a manner that the values predicted by the model equation and the values actually measured by the edge drop gage on the outlet side of the tandem rolling mill coincide. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an edge drop control method in tandem cold rolling of a strip-shaped metal sheet, and particularly to a tapered shape at one end, which is suitable for use in cold rolling of a strip-shaped metal sheet (hereinafter, referred to as a strip). The present invention relates to a method for controlling edge drop of a strip to be rolled by shifting a work roll having the roll in the sheet width direction.
[0002]
[Prior art]
A strip such as a steel plate is rolled by a rolling mill to produce one having a desired size. When a strip is rolled by a work roll in a rolling mill, a cross-sectional shape (hereinafter, referred to as a crown shape) in a longitudinal direction of the strip to be rolled, that is, a width direction orthogonal to a traveling direction of the strip to be rolled 1 during rolling, Normally, as shown exaggeratedly in FIG. 6, both edge portions are thinner than the central portion (hereinafter, referred to as edge drop). Here, the edge drop amount is, for example, the difference (t100−t15) between the plate thickness t100 at the position of 100 mm from the edge and the plate thickness t15 at the position of 15 mm in the center direction of the strip width, but also in the case of other measurement methods. is there. Rolled strips to be rolled are required to have the desired thickness accuracy, but at present, the demand for high quality and high dimensional accuracy of rolled products is increasing more and more. However, the demand for higher accuracy not only severely limits the thickness variation in the longitudinal direction, but also tends to make the thickness distribution in the width direction more severe. For this reason, conventionally, various techniques have been disclosed for more precisely controlling the edge drop amount at both ends in the width direction of the strip to be rolled after rolling.
[0003]
For example, in Japanese Patent Application Laid-Open No. Sho 61-2222619, a pair of rolled strips are provided so as to face each other with a tapered shape at one end in a direction opposite to the axial direction, and are each movable in the axial direction. Using a rolling stand equipped with work rolls (hereinafter referred to as a rolling stand for a tapered work roll), the thickness distribution at the end in the width direction on the outgoing side is calculated from the thickness distribution at the end on the incoming side in the width direction. A technique is disclosed in which the work roll of the stand is estimated, the estimated value is compared with the target thickness distribution, and the work roll of the stand is moved to a position where the difference between the two is minimized.
[0004]
Also, in Japanese Patent Application Laid-Open No. 3-243204, a rolling stand of a work roll having a tapered shape as described above is used, and a mathematical model showing an edge drop amount of a rolled material represented by at least two or more parameters is used. A technique is disclosed in which a roll stand exit side edge drop amount is predicted and the above-mentioned work roll is moved so that the edge drop amount matches a target value.
[0005]
Japanese Patent Application Laid-Open No. 4-294809 also uses a rolling stand for a work roll having a tapered shape as described above, and measures the thickness distribution on the entry side to determine the starting point of the edge drop region at both ends in the width direction of the plate. There is disclosed a technique in which a work roll is moved so that a boundary between a center portion of the work roll and a tapered shape portion coincides with a start point.
[0006]
In each case, a model formula for estimating the thickness distribution on the exit side in the width direction from the thickness distribution on the entrance side is created, and the input side edge drop amount of each of the work side and drive side is substituted into the model equation. Then, the output side edge drop amount of each of the work side and the drive side is estimated. JP-A-5-253609 and JP-A-5-285515 further disclose a method of updating a coefficient (model parameter) of a model formula in consideration of a control error due to a change in rolling characteristics of a rolling mill over time.
[0007]
[Problems to be solved by the invention]
However, in an actual tandem rolling mill, the polishing accuracy of the taper, the abrasion of the taper, the meandering of the strip to be rolled, the mill rigidity, and the like are different between the work side and the drive side of the rolling mill, and the output side edge is different. Affects drop volume. For example, even if the rolled strip having the same edge drop amount on both the input side and the roll side is rolled with the work roll shift position being the same on the work side and drive side, there will be a difference in the edge drop amount on the output side. There is. In the prior art, even though the difference in the amount of edge drop at both ends on the entry side of the strip to be rolled is taken into account, the difference in the rolling characteristics between the work side and the drive side of the rolling mill as described above is not taken into account. However, it was not possible to accurately estimate the amount of edge drop on the exit side of each drive side.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to control edge drop with high accuracy, improve the thickness accuracy in the width direction of the plate, and further improve the yield.
[0009]
[Means for Solving the Problems]
The present invention provides a work roll which is disposed to face one pair via a rolled strip, has a tapered shape at one end on the opposite side in the width direction of the rolled strip, and is movable in the axial direction. In a tandem rolling mill having one or more rolling stands provided, or in a rolling mill in which the work rolls are further crossed with each other, in advance, between the inlet side of the tandem rolling mill and the output side of the hot rolling step which is the preceding step. A learning term is used as a model formula for predicting the edge drop amount on the tandem rolling mill exit side including the measured edge drop amount of the strip to be rolled as a parameter (including the cross angle when a work roll is crossed). A model formula having constants on the work side and the drive side has been created separately, and the inlet side of the tandem rolling mill and the outlet side of the hot rolling process, which is the previous process, are prepared. The difference between the predicted value of the edge drop amount on the exit side of the tandem rolling mill and the target value of the edge drop amount on the exit side of the tandem rolling mill obtained by substituting the edge drop amounts of the work side and the drive side measured between the respective model formulas. The upper and lower work rolls of the stand are individually set at the work roll shift position that minimizes, and furthermore, the predicted value of the tandem rolling mill output side edge drop amount by the model formula and the measured value by the tandem rolling mill output side edge drop meter are calculated. This problem has been solved by updating the learning terms separately for the work side and the drive side so that they match.
[0010]
In the present invention, a pair of work rolls are provided opposite to each other via a strip to be rolled, have a tapered shape at one end in a direction opposite to the axial direction, and are each movable in the axial direction. Rolling stand, for example, in a tandem rolling mill having at least one stand including at least the first stand on the entry side, or a rolling mill in which the work rolls can be further crossed up and down with each other in a hot rolling step as a preceding step. The thickness distribution formed on the strip to be rolled is detected between the entry side of the tandem rolling mill and the hot rolling production side which is the preceding step. The parameters include the edge drop amount of the strip to be rolled and the work roll shift amount measured between the entrance side of the tandem rolling mill and the exit side of the hot rolling step, which is the preceding step, as a parameter. (A corner is also included as a parameter.) As a model formula for predicting the amount of edge drop on the exit side of a tandem rolling mill, a model formula having constants, which are learning terms, on the work side and the drive side is prepared in advance. The predicted value of the edge drop amount on the exit side of the tandem rolling mill and the exit side of the tandem rolling mill obtained by substituting the edge drop amount on the entrance side of the tandem rolling mill on each of the work side and drive side recognized from the detected thickness distribution into the respective model formulas The upper and lower work rolls of the stand are individually set at positions where the difference from the edge drop amount target value is minimized. Further, the learning term is updated separately for the work side and the drive side so that the predicted value of the edge drop amount on the exit side of the tandem rolling mill based on the model formula matches the actual value measured by the edge drop meter on the exit side of the tandem rolling mill. The thickness accuracy in the direction can be improved, and the yield can be further improved.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0012]
In the first embodiment of the present invention, for example, as shown in FIG. 1, in a first stand 4 of a tandem rolling mill, an edge drop of a strip 1 to be rolled is controlled and corrected by the present invention. FIG. 1A shows a work side, and FIG. 1B shows a drive side.
[0013]
As shown in FIG. 2, in the rolling mill 4, work rolls 5, 6 having a tapered shape at one end opposite to each other in the width direction of the strip 1 to be rolled (the left-right direction in FIG. 2), Each is provided so as to be movable in the axial direction as shown by arrows A and B. In FIG. 2, reference numerals 7 and 8 are backup rolls.
[0014]
Further, between the front side of the first stand 4 of the tandem rolling mill and the exit side of the hot rolling step, which is the preceding step, an inlet side for detecting the thickness distribution of the end of the strip 1 in the sheet width direction. An edge drop meter 2 is provided. The input side edge drop amounts of the work side and the drive side detected by the input side edge drop meter 2 are input to the edge drop control device 17.
[0015]
In the edge drop control device 17, the input side edge drop amounts ED _W0 and ED _D0 of the work side and the drive side are predicted from the following output side edge drop amounts ED _W1 and ED _D1 of the work side and the drive side. Is assigned to each model expression.
[0016]
ED _w1 = a · S _w + b · ED _w0 + c _w (1)
ED _D1 = a · S _D + b · ED _D0 + c _D (2)
_Here, ED W1, _{ED D1} each workpiece side, a tandem rolling mill exit side edge drop amount of the drive _side, ED W0, _{ED D0} respectively workpiece side, the drive-side tandem mill entry side edge drop _{amount, S} w, each S _D is the work side, work roll shift of the drive side, also, a, b and c _w, c _D is characteristic of the material (rolled strip) (material, thickness, plate width, etc.) by or rolling conditions It is a model parameter (effect coefficient) that changes, and is a value determined in advance by an experiment. Further, c _w and c _D are values updated as learning terms of the model equations of the work side and the drive side, respectively.
[0017]
Next, the optimum values of the work rolls 5 and 6 are set so that the difference between the output side edge drop amount at both ends in the sheet width direction and the output side edge drop target value predicted from the model formula is minimized for each of the work side and the drive side. The work roll shift amount is calculated and input to the work roll shift amount control device 18.
[0018]
The work roll shift amount control device 18 individually sets the work rolls 5 and 6 to the corresponding work roll shift positions according to the input work roll shift amount.
[0019]
The edge drop control device 17 further calculates the output side end edge drop amounts obtained by substituting the input side edge drop amounts and the work roll shift amounts of the work side and the drive side when actually rolling into the respective model equations. as measured value of the predicted value and the tandem rolling mill exit side edge drop meter 3 and are aligned, the learning term c _w, c _D is updated work side, the drive side separately. The model parameters are updated by exponential smoothing.
[0020]
For example, the edge drop prediction equation of the work side (1), and updates the model parameters c _w in _c'w based on the following equation.
[0021]
c ′ _w = α · [ED _w1 − (a · S _w + b · ED _w0 + c _w )] + (1−α) · c _w (3)
Here, _c'w: currently calculated value of the model parameter _{c w c w:} previous value of the model parameter _{c w} alpha: exponential smoothing coefficient 0 <alpha <1
ED _w1: actual entry side edge drop amount of the work side when rolled ED _w0, tandem mill exit side edge drop quantity obtained by work roll shift S _w (work side by tandem rolling mill exit side edge drop meter Measured value)
[0022]
Further, in the drive-side edge drop prediction equation (2), and updates the model parameters c _D in _c'D calculated based on the following equation.
[0023]
c ′ _D = α · [ED _D1 − (a · S _D + b · ED _D0 + c _D )] + (1−α) · C _D (4)
Here, _c'D: currently calculated value of the model parameter _{c D c D:} previous value of the model parameter _{c D} alpha: exponential smoothing coefficient 0 <alpha <1
ED _D1 : Drive side entrance edge drop amount ED _D0 when actually rolling, tandem rolling mill exit side edge drop amount obtained from work roll shift amount _SD (drive side by tandem rolling mill exit side edge drop meter) Measured value)
[0024]
Next, a second embodiment of the present invention will be described.
[0025]
This embodiment is an edge drop control system for controlling and correcting an edge drop of a strip 1 to be rolled in a first stand 4 of a tandem rolling mill according to the present invention, as shown in FIG. 3, for example. FIG. 3A shows the work side, and FIG. 3B shows the drive side.
[0026]
As shown in FIG. 4, in the rolling mill 4, as in the first embodiment, the work rolls 5, 6 each having a tapered shape on one side end can cross each other up and down as shown by an arrow C. It is.
[0027]
Further, between the front side of the first stand 4 of the tandem rolling mill and the exit side of the hot rolling step, which is the preceding step, an inlet side for detecting the thickness distribution of the end of the strip 1 in the sheet width direction. An edge drop meter 2 is provided. The input side edge drop amounts of the work side and the drive side detected by the input side edge drop meter 2 are input to the edge drop control device 17.
[0028]
In the edge drop control device 17, the input side edge drop amounts ED _W0 , ED _D0 and the work roll cross angle θ of each of the work side and the drive side are set to the following output side edge drop amounts ED _W1 of the work side and the drive side. ED _D1 is substituted into each model equation for prediction.
[0029]
ED _W1 = f _W (S _W , ED _W0 , θ) + c _W (5)
ED _D1 = f _D (S _D , ED _D0 , θ) + c _D (6)
_Here, ED W1, _{ED D1} each workpiece side, a tandem rolling mill exit side edge drop amount of the drive _side, ED W0, _{ED D0} each workpiece side, tandem mill entry side edge drop amount of the drive _{side, S} W, _SD is the work roll shift amount on the work side and the drive side, and θ is the work roll cross angle (see FIG. 4). Equations (5) and (6) include model parameters (effect coefficients) that change depending on the characteristics (material, plate thickness, plate width, etc.) of the material (rolled strip) and rolling conditions. c _W and c _D are learning terms of the model equations of the work side and the drive side, respectively.
[0030]
Next, the work rolls 5 and 6 are respectively adjusted so that the difference between the output edge drop amounts at both ends in the sheet width direction predicted from the model formula and the output edge drop target values for each of them is minimized for each of the work side and the drive side. Is calculated and input to the work roll shift amount control device 18.
[0031]
The work roll shift amount control device 18 individually sets the work rolls 5 and 6 to the corresponding work roll shift positions according to the input work roll shift amount.
[0032]
Further, in the edge drop control device 17, the output side obtained by substituting the input side edge drop amount, the work roll shift amount, and the work roll cross angle of each of the work side and the drive side at the time of actual rolling into the respective model equations. as predicted value and the measured value of the tandem rolling mill exit side edge drop meter 3 across the edge drop amount and are aligned, the learning term c _W, c _D is updated work side, the drive side separately. The model parameters are updated by exponential smoothing.
[0033]
For example, in the work side of the edge drop prediction equation (5), and updates the model parameters c _w in _c'w based on the following equation.
[0034]
_{c'w = α · [ED w1} - {f w (S w, ED w0, θ) + c w}] + (1-α) · c w
… (7)
Here, _c'w: currently calculated value of the model parameter _{c w c w:} previous value of the model parameter _{c w} alpha: exponential smoothing coefficient 0 <alpha <1
ED _w1: actually rolled workpiece side of the ingress edge drop amount ED w0 of _time, work side by work roll shift S tandem mill exit side edge drop quantity obtained by _w (tandem mill delivery side edge drop meter 3 Measured value)
[0035]
Further, in the drive-side edge drop prediction equation (6), and updates the model parameters c _D in _c'D calculated based on the following equation.
[0036]
c ′ _D = α · [ED _D1 − {f _D (S _D , ED _D0 , θ) + c _D }] + (1−α) · c _D
… (8)
Here, _c'D: currently calculated value of the model parameter _{c D c D:} previous value of the model parameter _{c D} alpha: exponential smoothing coefficient 0 <alpha <1
ED _D1 : Drive side entrance edge drop amount ED _D0 at the time of actual rolling, tandem rolling mill exit side edge drop amount obtained from work roll shift amount _SD (drive side by tandem rolling mill exit side edge drop total 3) Measured value)
[0037]
【Example】
In order to verify the effect of the present invention, 150 low carbon steels were used in both the case where the conventional example (Japanese Unexamined Patent Application Publication No. 61-2222619) was applied and the case where the example of the present invention (first embodiment) was applied. Cold tandem rolling was performed, and the actual value of the edge drop amount was compared between the work side and the drive side. As shown in FIG. 6, the edge drop amount was defined as a sheet thickness difference (t100-t15) between the 100 mm position and the same 15 mm position from the edge toward the center of the band width. When the edge drop amount is positive, the edge is up, and when the edge drop amount is negative, the edge is dropped. Here, the edge drop ratio (%) in the figure was calculated as: tandem rolling mill exit side edge drop amount / tandem rolling mill exit side plate thickness × 100.
[0038]
In comparison with the conventional method, it can be seen that in the present invention, the variation of the edge drop amount is small, and the variation falls within the target range between the two vertical lines. Therefore, it can be seen that the edge drop amount can be controlled as desired with higher accuracy.
[0039]
【The invention's effect】
As described above, according to the present invention, in consideration of the difference in the rolling characteristics between the work side and the drive side of the rolling mill, the edge drop amount at both ends in the sheet width direction is more accurately controlled, so that And the yield can be further improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a tandem cold rolling mill according to a first embodiment to which the present invention is applied; FIG. 2 is a front view showing a main part configuration of a rolling stand; FIG. FIG. 4 is a plan view showing a configuration of a main part of a rolling stand according to the second embodiment. FIG. 5 is a diagram showing a result of control using the same model of a work side and a drive side, FIG. 6 is a diagram comparing the results of control using individual learning terms for the side and the drive side. FIG. 6 is a cross-sectional view illustrating the definition of the edge drop amount.
DESCRIPTION OF SYMBOLS 1 ... Strip to be rolled 2 ... Edge drop total on tandem rolling mill 3 ... Edge drop total on tandem rolling machine 4 ... First stand 5 and 6 of tandem rolling mill ... Work roll with one taper 7, 8 ... Backup roll 17 ... Edge drop control device 18 ... Work roll shift amount control device

Claims (2)

A rolling device having a pair of work rolls disposed opposite to each other with a rolled strip in between and having a tapered shape at one end on the opposite side in the width direction of the rolled strip and each of which is movable in the axial direction. In a tandem rolling mill having one or more stands, in advance, the edge drop amount and the work roll shift amount of the strip to be rolled measured between the tandem rolling mill entrance side and the hot rolling process exit side which is the preceding step. As a model formula for predicting the tandem rolling mill exit side edge drop amount including as a parameter, a model formula having a constant which is a learning term on a work side and a drive side individually is created,
Edge drop of tandem rolling mill obtained by substituting the edge drop amount of each of the work side and drive side measured between the entrance side of tandem rolling mill and the exit side of hot rolling process, which is the previous process, into each model formula. The upper and lower work rolls of the stand are individually set at the work roll shift position that minimizes the difference between the amount predicted value and the target value of the edge drop amount on the exit side of the tandem rolling mill,
Further, the learning term is updated separately for the work side and the drive side so that the predicted value based on the model formula and the actual value measured by the edge drop meter on the output side of the tandem rolling mill are updated. Control method. 2. The edge drop control method according to claim 1, wherein upper and lower work rolls of the rolling stand are crossed and rolled.

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