JPH0857515A - Method for controlling edge drop at time of cold rolling - Google Patents

Abstract

PURPOSE: To prevent the deterioration of operability by previously preparing a numerical model taking differences in thickness as parameters and controlling a roll bender and roll shift based on the numerical model in which the measured value of the profile of a sheet is taken as a variable. CONSTITUTION: The differences in thickness to the reference position in plural points (x), (y) where distances from the end of the sheet are different are expressed by Fx, Fy. The edge drop of the metallic sheet to be rolled is expressed by the plural parameters Fx, Fy and the numerical model is previously prepared. The profile of base stock before rolling or the profile on the outlet side of the final stand is continuously measured. Based on the numerical model in which the measured values are taken as variables, the work roll bender, intermediate roll bender and intermediate roll shift at each stand are controlled so that the edge drop on the outlet side of the final stand coincides with the target value. Correction is always executed at each stand, so the breaking of sheet due to the deterioration in shape on the midway is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge drop control method for suppressing a defective shape of an end portion which tends to occur during rolling of a metal sheet.

[0002]

2. Description of the Related Art A cold rolled metal sheet is required to have a uniform thickness distribution in the sheet width direction. But,
An edge drop occurs near the edge in the sheet width direction due to plastic flow during rolling. As a means for suppressing edge drop, a tapered work roll shift method is usually adopted in which the roll body end portion is tapered and the work roll is shifted in the plate width direction. For example, Japanese Patent Application Laid-Open No. 4-91811 discloses that the optimum shift amount of a tapered work roll is controlled in order to prevent an edge drop in a rolling mill including a plurality of stands.
In this method, the edge profile is represented by a plurality of parameters. Then, the difference between the edge profile during rolling and the target edge profile on the exit side of the final pass is used as a dependent variable, and the width direction shift amount of the work roll is calculated according to a mathematical model in which the parameters representing the edge profile before rolling and the shift position are independent variables. Is being adjusted every moment. Further, JP-A-3-243204 discloses setting an optimum shift amount of a tapered work roll in order to control edge drop in a rolling mill including a plurality of stands. In this method, the edge drop amount on the delivery side of the final pass rolling mill is predicted from a mathematical model that is obtained in advance, and the work roll shift amount of the upstream rolling mill is set according to the prediction result.

[0003]

In the tapered work roll shift method, the edge drop is controlled by constantly correcting the work roll shift amount during rolling. Therefore, it takes a long time to move the work roll and the responsiveness is low. To taper the roll barrel end,
Work roll polishing is required. Further, when rolling a metal plate having a large plate width, it is necessary to properly use a plurality of tapered work rolls according to the plate width due to restrictions of the rolling mill regarding roll shift. As a result, it is necessary to replace the rolls, and the operability is reduced as compared with normal rolling. The present invention has been devised to solve such a problem, and effectively controls the edge drop by a work roll bender other than a tapered work roll, an intermediate roll bender, an intermediate roll shift, or the like, to obtain a strip width. The object is to obtain a metal plate having excellent uniformity of plate thickness distribution in the direction.

[0004]

In order to achieve the object, an edge drop control method according to the present invention is designed to achieve cold cooling by using a difference in plate thickness from a reference position at a plurality of points having different distances from a plate edge as a plurality of parameters. Representing the edge drop of the metal plate to be rolled, while creating a mathematical model representing these parameters in advance, continuously measuring the material profile before rolling or the profile on the exit side of the final stand, the mathematical expression with the measured value as a variable Based on the model, the work roll bender, intermediate roll bender, and intermediate roll shifter should be used on multiple stands from the first stand to the final stand one step before so that the edge drop on the exit side of the final stand matches the target value. The feature is that the edge drop improvement amount is constantly corrected by controlling one or more. .

The continuous measurement of the profile is performed on the material or the rolled material on the delivery side of the final stand, and the work roll bender, the intermediate roll bender, the intermediate roll shift, etc. are feed-forward-controlled or feedback-controlled accordingly. Alternatively, based on the mathematical model with the measured value as a variable, the work roll bender is provided at a plurality of stands from the first stand to the final stand one step before so that the edge drop on the exit side of the final stand matches the target value. It is also possible to adopt a preset method in which the edge drop improvement amount is set by controlling one or more of the intermediate roll bender and the intermediate roll shift.

The edge drop of the material is represented by F _x and F _y defined by the equations (1) and (2), respectively.
As shown in FIG. 1, F _x and F _y indicate the amount of reduction in the wall thickness of the material at the positions of distances x and y from the plate width direction end. The edge drop on the exit side of the final stand is represented by E _x and E _y defined by the equations (3) and (4), respectively. E
_As shown in FIG. 2, _x and E _y also indicate the amount of reduction in wall thickness at the positions of distances x and y from the end in the plate width direction. _{F x = H k -H x ····} (1) F y = H k -H y ···· (2) E x = h k -h x ···· (3) E y = h k -h _y ···· (4)

Where H _x , H _y and H _k are the plate thickness of the material at the distances x, y and k from the plate edge, respectively, and h
_x , h _y and h _k are plate thicknesses at the exit side of the final stand at the distances of x, y and k from the plate end, respectively. However,
Let x <y <k. The distances x, y, and k are empirically selected so as to properly represent the edge drop and to obtain an accurate mathematical model. The edge drops E _x and E _y on the exit side of the final stand defined as above are shown in FIG.
As shown in FIG. 6, there is a substantially linear relationship with the work roll bender, the intermediate roll bender, the intermediate roll shift amount, and the edge drop of the material at the same position. Therefore, the edge drop can be predicted by the following equations (5) and (6).

[0008]

[Equation 1]

In the formula, i is the rolling mill at the i-th stand from the upstream stand side, n is the number of stands, W _i is the control amount of the work roll bender of the i stand, I _i is the control amount of the intermediate roll bender of the i stand, δ _i is the control amount of the intermediate roll shift of the i stand, a _1i , a _2i , a _3i , a ₄ , a ₅ ,
b _1i , b _2i , b _3i , b ₄ , and b ₅ represent influence coefficients. Influence coefficients a _1i , a _2i , a _3i , a ₄ , b _1i , b _2i , b _3i , b ₄
Are respectively obtained from experiments or simulations by an analytical model in which elastic deformation analysis of the roll and plastic deformation analysis of the material are coupled. That is, when all other rolling conditions are made constant and the control amounts W _i , I _i , δ _{i of} each shape control means and the material edge drop amounts F ₁₀ , F ₃₀ are changed, the control amounts W _i , I are obtained. _i , δ _i , the edge drop amounts F ₁₀ , F _{30 of the} material, and the edge drop amount E on the delivery side of the final stand
It is calculated as the slope in the linear relationship established between ₁₀ and E ₃₀ . The influence coefficients a ₅ and b ₅ are
It is obtained as a constant term in the relationship.

At the same stand, the edge drop control characteristics of the work roll bender, the intermediate roll bender, and the intermediate roll shift are very similar as shown in FIG. 7, and can be expressed by the relation of the equation (7). it can. b _1i / a _1i = b _2i / a _2i = b _3i / a _3i (7) Therefore, the edge drop improvement amount (final stand exit side) at the distance x from the plate edge given by the i stand is S _xi
Then, _Ex and _Ey are expressed by the following equations (8) and (9), respectively.

[0011]

[Equation 2]

Here, b _6i is an influence coefficient and is expressed by the equation (1
0). _b6i = _b1i / _a1i ... (10) In feedforward control, the raw material profile before rolling is continuously measured, and _Fx and _Fy are calculated from Formulas (1) and (2). Then, so that E _x and E _y expressed by the equations (8) and (9) become the target values E _x 'and E _y ', respectively, the final stand output at the point of distance x from the plate edge given by the i stand. The edge drop improvement amount S _xi on the side is constantly corrected. Here, an X-ray plate thickness meter or the like that is movable in the plate width direction is used for measuring the material profile before rolling. In the preset control, the final values at the distance x from the plate edge given by the i stand are set so that E _x and E _y expressed by the equations (8) and (9) become the target values E _x 'and E _y ', respectively. The edge drop improvement amount S _xi on the stand output side is determined.

If the amount of edge drop improvement in each stand is too large, there is a risk that the shape on the way deteriorates and plate breakage occurs. This plate rupture can be prevented by providing an upper limit value S _xi ^MAX for the edge drop improvement amount in each stand. When the target values E _x 'and E _y ' of edge drop cannot be obtained by setting the upper limit value S _xi ^MAX , equation (11)
Introducing the evaluation function J ₁ indicated by, the edge drop improvement amount S _xi at each stand so that the evaluation function J ₁ is minimized.
Is constantly corrected. _{J 1 = w x (E x} -E x ') 2 + w y (E y -E y') ² ... (11), w _x, w _y denotes a weighting factor. When the target values E _x 'and E _y ' of the edge drop are obtained by the rolling mill having four or more stands, the edge drop improvement amount S _{xi at} each stand is obtained.
As for, any combination can be adopted. However, considering the shape in the middle, it is possible to introduce the evaluation function J ₂ as shown in Expression (12) and constantly correct the edge drop improvement amount S _xi in each stand so that the evaluation function J ₂ is minimized. preferable.

[0014]

(Equation 3)

The work roll bender control amount W _i , the intermediate roll bender control amount I _i , and the intermediate roll shift control amount δ _{i with} respect to the edge drop improvement amount S _xi in each stand can be set in any combination. it can. However, in consideration of responsiveness, it is preferable to give priority to the control amounts of the work roll bender and the intermediate roll bender over the intermediate roll shift. In addition, the edge drop on the exit side of the final stand is expressed by the equations (3) and (4) as E _x and E _y.
However, it is also possible to take E _z expressed by the equation (13) and express it. E _z of the equation (13) is further _calculated by the equation (1
It can also be expressed by Expression (15) from the relationship of 4).

[0016]

[Equation 4]

In the equation, c _6i represents the influence coefficient, and the following equation (1
It is represented by 6). _{c 6i = c 1i / a 1i} ···· (16) also has an evaluation function J ₃ represented by the following formula (17) is used. J ₃ = w _x (E _x −E _x ') ² + w _y (E _y −E _y ') ² + w _z (E _z −E _z ') ² (17) In feedback control, the final stand output The side edge drop is the work roll bender, the intermediate roll bender,
Since it has a linear relationship with the intermediate roll shift and the like, the edge drop control formula according to the following formulas (18) and (19) is used.

[0018]

(Equation 5)

In the formula, i is the rolling mill at the i-th stand from the upstream stand side, n is the number of stands, ΔW _i is the correction amount of the work roll bender force W _i of the i stand, and ΔI _i is the intermediate roll bender force of the i stand. The correction amount of I _i , Δδ _i, is the intermediate roll shift amount δ _i of the i stand. E _x ¹ and E _y ¹
_Are the values of E _x and E _y calculated by the equations (3) and (4) from the profile on the exit side of the final stand, which are continuously measured, and are represented by the equations (20) and (21), respectively. It E _x ¹ = h _k ¹ −h _x ¹ ··· (20) E _y ¹ = h _k ¹ −h _y ¹ ··· (21)

Here, h _x ¹ , h _y ¹ and h _k ¹ indicate the plate thicknesses on the delivery side of the final stand at the distances x, y and k from the continuously measured plate edges, respectively. Also in this case, the edge drop control characteristics of the work roll bender, the intermediate roll bender, and the intermediate roll shift on the same stand are very similar to each other, and the above-mentioned formula (7) is established. Thus, when expressed from a plate edge given by i stand correction amount of edge drop improvement amount S _xi final stand delivery side at a distance of x in [Delta] S _xi, E _x and E _y are respectively the following formulas (2
It is represented by 2) and (23).

[0021]

(Equation 6)

Therefore, the profile on the delivery side of the final stand during rolling is continuously measured, E _x ¹ and E _y ¹ are calculated according to equations (20) and (21), and equations (22) and (23) are used. Correction of the edge drop improvement amount S _xi on the exit side of the final stand at a point of a distance x from the plate edge given by the i stand so that the expressed E _x and E _y become the target values E _x 'and E _y ', respectively. Always set the quantity ΔS _xi . Also in this case, when there is a fear that the intermediate shape due to the excessive edge drop improvement amount in each stand may be deteriorated, the above equation (1
It is also possible to introduce the evaluation function J ₁ represented by 1) and always set the correction amount ΔS _xi of the edge drop improvement amount S _xi in each stand so that the evaluation function J ₁ is minimized.
It is also possible to introduce the evaluation function J ₂ represented by the equation (12) and always set the correction amount ΔS _xi of the edge drop improvement amount S _xi in each stand so that the evaluation function J ₂ is minimized.

[0023]

[Function] Unlike the tapered work roll shift method, edge drop control by the work roll bender, intermediate roll bender, and intermediate roll shift does not require work roll polishing for tapering. The exchange of rolls depending on the usage is also omitted. Therefore, the edge drop is controlled without reducing the operability. Also, work roll vendor,
The edge drop control using the intermediate roll bender and the intermediate roll shift has higher responsiveness than the tapered work roll shift method that requires a long time to move the work roll. Moreover, there is an advantage over the taper work roll shift method in that the increase in tension at the plate end is suppressed and plate breakage is less likely to occur.

The tension in the vicinity of the plate edge of the stand for improving the edge drop was measured at a position 10 mm from the plate edge, and as shown in FIG. 8, it increased as the improvement amount of the edge drop increased. However, comparing with the same edge drop improvement amount, when the edge drop is improved by the work roll bender, the intermediate roll bender, and the intermediate roll shift, compared with the tapered work roll shift method, the tension increase amount near the plate edge is increased. Less is.
This is because the stagnation of improvement in edge drop differs between the two. When the edge drop is improved by the work roll bender, the intermediate roll bender, and the intermediate roll shift, the difference in the elongation rate with respect to the center of the sheet width changes in the entire sheet width direction. On the other hand, when improving the edge drop with a tapered work roll, the difference in the elongation rate with respect to the center of the plate width changes only near the tapered plate edge, so the tension tends to increase intensively near the plate edge. . as a result,
In the tapered work roll method, the risk of plate breakage increases as described above.

The optimum control method for edge drop is preset control + feedforward control or preset control + feedback control. The preset control is for initializing the control amount of each shape control means and is indispensable for controlling the edge drop from the beginning of rolling. Further, since the profile of the material changes during rolling, the profile after rolling also changes. Correspondingly, there is feedforward control and / or feedback control as control for correcting the control amount of each shape control means during rolling. The feed-forward control has an advantage that the control time delay is smaller than that of the feedback control, but the control model error is likely to occur. Feedback control is superior in terms of accuracy.

[0026]

【Example】

Example 1 (Feedforward Control) In this example, a tandem rolling mill 5 provided with four stands 1 to 4 as shown in FIG. 9 was used. The rolling conditions are input to the host computer 6, and the process computer 7 sends No.
The optimum edge drop improvement amount for the first to third stands was calculated and input to the shape control means 8. Further, the pre-rolling profile of the steel sheet 10 being rolled was continuously measured by the X-ray plate thickness meter 9 movable in the plate width direction, and the measured value was taken into the host computer 6. The process computer 7 calculates the optimum edge drop improvement amount based on the measured value and the influence coefficient obtained in advance for each product type.
The calculated value is input to the shape control means 8 and feed-forward control of rolling conditions is performed at each stand.

Since the plate thickness guarantee point is 10 mm, x = 1
It was set to 0 mm. Further, when the edge drop is controlled and reduced, an edge-up which is a problem in a post process is likely to occur in the vicinity of 30 mm from the plate edge, so y = 30 mm is set. Under the rolling conditions of this example, the range in which the plate thickness does not change due to the edge drop control is 50 to 100 m from the plate edge.
Since it is located closer to the center in the plate width direction than m, the reference point for edge drop amount evaluation was set to k = 100 mm. The edge drop of the material is expressed by equations (24) and (25) as F ₁₀ ,
The edge drop on the exit side of the final stand is defined by F ₃₀ , and E ₁₀ and E ₃₀ shown in equations (26) and (27). _{F 10 = H 100 -H 10 ····} (24) F 30 = H 100 -H 30 ···· (25) E 10 = h 100 -h 10 ···· (26) E 30 = h 100 -H ₃₀ ... (27)

E ₁₀ and E ₃₀ are represented by equations (28) and (29), respectively. E ₁₀ and E ₃₀ are target values E, respectively
So that ₁₀ 'and E _30', the material profile before rolling continuously measured by X-ray thickness gauge 9, calculates the F ₁₀ and F ₃₀ in accordance with equation (24) and (25). And N
The edge drop improvement amount S _10i on the delivery side of the final stand at a distance of 10 mm from the plate edge given by the first to third stands was always corrected according to the following equations (28) and (29).

[0029]

(Equation 7)

At this time, in order to prevent the plate from breaking due to the deterioration of the shape on the way, the upper limit value S _10i ^MAX of the edge drop improvement amount in each stand for each manufacturing type is given a margin to prevent the plate from breaking. It was set according to the conditions. Upper limit S _10i
^When the target values E ₁₀ 'and E ₃₀ ' of the edge drop cannot be obtained by the setting of ^MAX, the evaluation function J shown in the equation (30)
₁ was introduced and the edge drop improvement amount S _10i in each stand was corrected so that the evaluation function J ₁ was minimized. _{J 1 = w 10 (E 10} -E 10 ') 2 + w 30 (E 30 -E 30') weighting factors w ₁₀ and w ₃₀ in ² .... (30) are each w ₁₀ = 1 and w ₃₀ = 2. Target value of edge drop E ₁₀ 'and E
_{When 30} 'is obtained, any combination can be adopted for the edge drop improvement amount S _10i in each stand.
In consideration of the adverse effect of the shape on the way, the evaluation function J ₂ of Expression (31) was introduced, and the edge drop improvement amount S _10i in each stand was constantly corrected so that the evaluation function J ₂ was minimized.

[0031]

[Equation 8]

When correcting the edge drop improvement amount S _10i , the control amounts of the work roll bender and the intermediate roll bender were corrected in consideration of responsiveness. Figure 10
Is a flow showing the procedure described above. The actual values of edge drop are compared with the target values E ₁₀ ′ and E ₃₀ ′ and shown in FIGS. 11 and 12. Further, the actual values of the edge drop by the conventional method are shown in FIGS. 13 and 14 in comparison with the target values E ₁₀ ′ and E ₃₀ ′. In the conventional method, the operator manually sets the control amount of each shape control means empirically. In the conventional method, the difference between the actual value of the edge drop and the target values E ₁₀ ′ and E ₃₀ ′ is ± 10 μm or more, and the edge drop control was insufficient.

On the other hand, when the control is performed according to the present invention, the actual value of the edge drop is ±± with reference to the target values E ₁₀ 'and E ₃₀ ' as shown in FIGS.
It is within the range of 5 μm, and it can be seen that the edge drop is improved with high accuracy. In addition, the upper limit of the amount of edge drop improvement at each stand for each product type S _10i ^{M
Since AX} is set, plate breakage due to deterioration of the shape on the way is also prevented. As a result, in No. 4 stand,
Since shape control is performed without edge drop control,
A product with a good shape was obtained.

Embodiment 2 (Feedback Control) In this embodiment, the equipment configuration is the same as that of FIG. 9 except that the X-ray plate thickness gauge 9 is arranged on the No. 4 stand exit side, and rolling is performed on the No. 4 stand exit side. The profile of the steel plate 10 was continuously measured by the X-ray plate thickness meter 9. The measured value of the plate thickness is taken into the host computer 6, and the optimum correction amount of the edge drop improvement amount in No. 1 to 3 stands is calculated by the process computer 7 according to the measured value and the influence coefficient obtained in advance for each product type. The shape control means 8 performs feedback control.

At this time, x = 10 m as in the first embodiment.
Setting m, y = 30 mm and k = 100 mm, No. 4
The edge drop on the stand exit side can be calculated using the formulas (32) and (3
It is represented by E ₁₀ and E ₃₀ defined in 3). _{E 10 = h 100 -h 10 ····} (32) E 30 = h 100 -h 30 ···· (33) E 10 and E ₃₀ is represented by each formula (34) and (35) . The profile on the outgoing side of the No. 4 stand during rolling was continuously measured with the X-ray plate thickness meter 9 so that E ₁₀ and E ₃₀ would be the target values E ₁₀ 'and E ₃₀ ', respectively, and the formula (36) was used. and to calculate the E ₁₀ ¹ and E ₃₀ ¹ in accordance with (37). Then, the correction amount ΔS _10i of the edge drop improvement amount S _10i on the exit side of the final stand at a point 10 mm away from the plate end given by No. 1 to 3 stands is always set according to the following equations (34) and (35).

[0036]

[Equation 9]

At this time, in order to prevent the plate from breaking due to the deterioration of the shape on the way, an upper limit value S _10i ^MAX of the edge drop improvement amount in each stand is set for each manufacturing type. Target value E of edge drop depending on the setting of upper limit value S _10i ^MAX
_{When 10} ′ and E ₃₀ ′ cannot be obtained, the evaluation function J ₁ shown in Expression (38) is introduced, and the correction amount ΔS _10i of the edge drop improvement amount S _10i in each stand is minimized so that the evaluation function J ₁ is minimized. Was always set. J ₁ = w ₁₀ (E ₁₀ −E ₁₀ ′) ² + w ₃₀ (E ₃₀ −E ₃₀ ′) ² ... (38) The weighting factors w ₁₀ and w ₃₀ in the equation are w ₁₀ = 1 and w ₃₀ = 2. Target value of edge drop E ₁₀ 'and E
_{When 30} 'is obtained, any combination can be adopted for the correction amount ΔS _10i of the edge drop improvement amount S _10i in each stand, but considering the adverse effect due to the shape in the middle, the evaluation function J ₂ of the formula (39) To introduce the evaluation function J ₂
The correction amount ΔS _10i of the edge drop improvement amount S _10i in each stand is always set so that

[0038]

[Equation 10]

When correcting the edge drop improvement amount S _10i , the control amounts of the work roll bender and the intermediate roll bender were corrected in consideration of responsiveness. FIG.
Is a flow showing the procedure described above. The actual values of edge drop are compared with the target values E ₁₀ ′ and E ₃₀ ′ and shown in FIGS. 16 and 17. As shown in FIGS. 16 and 17, the actual value of the edge drop is within ± 5 μm with reference to the target values E ₁₀ 'and E ₃₀ ', and the edge drop is improved with high accuracy. I understand. Further, since the upper limit S _10i ^MAX of the edge drop improvement amount at each stand is set for each manufacturing type, plate breakage due to deterioration of the shape on the way is also prevented. as a result,
With the No. 4 stand, shape control was performed without performing edge drop control, so a product with a good shape was obtained.

Embodiment 3 (Preset Control) In this embodiment, four stands 1 to 1 of the equipment configuration shown in FIG.
The tandem rolling mill 5 provided with No. 4 was used to input the edge drop information of the material and the rolling conditions into the host computer 6. The process computer 7 calculates the optimal improvement amount of the edge drop in the No. 1 to 3 stands according to the information from the host computer 6 based on the influence coefficient obtained in advance for each manufacturing type, and via the shape control means 8. I made a preset. As in Example 1, x = 10 mm, y = 30
mm and k = 100 mm, and the edge drop on the exit side of the final stand is given by E ₁₀ shown in equations (40) and (41),
Defined at E ₃₀ . _{E 10 = h 100 -h 10 ····} (40) E 30 = h 100 -h 30 ···· (41) E 10 and E ₃₀ is represented by each formula (42) and (43) . The edge drop improvement amount S _10i on the exit side of the final stand at the point 10 mm from the plate edge given by No. 1 to 3 stands is determined so that E ₁₀ and E ₃₀ become the target values E ₁₀ ′ and E ₃₀ ′, respectively. did.

[0041]

[Equation 11]

At this time, in order to prevent the plate from breaking due to the deterioration of the shape on the way, an upper limit value S _10i ^MAX of the edge drop improvement amount in each stand is set for each manufacturing type. Target value E of edge drop depending on the setting of upper limit value S _10i ^MAX
_{When 10} ′ and E ₃₀ ′ are not obtained, the evaluation function J ₁ shown in Expression (44) is introduced, and the edge drop improvement amount S _10i in each stand is determined so that the evaluation function J ₁ is minimized. J ₁ = w ₁₀ (E ₁₀ −E ₁₀ ′) ² + w ₃₀ (E ₃₀ −E ₃₀ ′) ² (44) The weighting factors w ₁₀ and w ₃₀ in the equation are w ₁₀ = 1 and w ₃₀ = 2. Target value of edge drop E ₁₀ 'and E
_{When 30} 'is obtained, any combination can be adopted for the edge drop improvement amount S _10i in each stand.
The evaluation function J ₂ of Expression (45) was introduced in consideration of the adverse effect of the shape on the way, and the edge drop improvement amount S _10i in each stand was determined so that the evaluation function J ₂ was minimized.

[0043]

[Equation 12]

FIG. 19 is a flow chart showing the procedure described above. The actual values of the edge drops are compared with the target values E ₁₀ 'and E ₃₀ ' and shown in FIGS. 20 and 21. The actual value of the edge drop is within ± 5 μm with reference to the target values E ₁₀ ′ and E ₃₀ ′ as shown in FIGS. 20 and 21, and the edge drop is improved with high accuracy. I understand. Further, since the upper limit S _10i ^MAX of the edge drop improvement amount at each stand is set for each manufacturing type, plate breakage due to deterioration of the shape on the way is also prevented. As a result, in the No. 4 stand, since the shape control was performed without performing the edge drop control, a product having a good shape was obtained.

[0045]

As described above, according to the present invention, the edge drop on the exit side of the final stand can be made to coincide with the target edge drop, and the plate breakage due to the deterioration of the shape on the way can be prevented. A good shape can be obtained on the stand exit side. Further, since the work roll bender, the intermediate roll bender, the intermediate roll shift, etc. are used as the edge drop control means, the operability is not lowered unlike the edge drop control by the tapered work roll shift method.

[Brief description of drawings]

FIG. 1 Edge drop of material represented by two parameters F _x and F _y

FIG. 2 is an edge drop on the exit side of the final stand represented by two parameters E _x and E _y.

[Fig. 3] Relationship between control amount of work roll bender and edge drop on final stand exit side

[Fig. 4] Relationship between the control amount of the intermediate roll bender and the edge drop on the exit side of the final stand

FIG. 5: Relationship between control amount of intermediate roll shift and edge drop on final stand exit side

[Fig. 6] Relationship between edge drop of material at the same position and edge drop on the exit side of the final stand

FIG. 7 is a comparative diagram showing edge drop control characteristics of a work roll bender, an intermediate roll bender, and an intermediate roll shift on the same stand.

FIG. 8: Relationship between edge drop improvement amount and tension near plate edge

9 is a tandem rolling mill used in Example 1. FIG.

FIG. 10 is a flow showing a procedure in the first embodiment.

FIG. 11 is a comparison between the actual value of the edge drop and the target value E ₁₀ ′ in the first embodiment.

FIG. 12: Comparison between the actual value of edge drop and the target value E ₃₀ 'in Example 1

FIG. 13: Comparison between the actual value of the edge drop and the target value E ₁₀ 'in the conventional method

FIG. 14: Comparison between the actual value of the edge drop and the target value E ₃₀ 'in the conventional method

FIG. 15 is a flowchart showing the procedure in the second embodiment.

16 is a comparison between the actual value of edge drop and the target value E ₁₀ 'in Example 2. FIG.

FIG. 17: Comparison between the actual value of edge drop and the target value E ₃₀ 'in Example 2

FIG. 18: Control mechanism of tandem rolling mill used in Example 3

FIG. 19 is a flow chart showing the procedure in the third embodiment.

FIG. 20: Comparison between the actual value of edge drop and the target value E ₁₀ 'in Example 3

FIG. 21: Comparison between the actual value of edge drop and the target value E ₃₀ 'in Example 3

[Explanation of symbols]

1-4: stand 5: tandem rolling mill 6: host computer 7: process computer 8: shape control means 9: X-ray plate thickness gauge 10: steel plate

Claims (2)

[Claims] 1. An edge drop of a cold-rolled metal sheet is represented by a plurality of parameters, which are differences in sheet thickness from a reference position at a plurality of points having different distances from the sheet edge, and a mathematical model representing these parameters is created in advance. In addition, continuously measure the material profile before rolling or the profile on the exit side of the final stand, and use the measured value as a variable based on the above mathematical model so that the edge drop on the exit side of the final stand matches the target value. In addition, the edge drop improvement amount is constantly corrected by controlling one or more of the work roll bender, the intermediate roll bender, and the intermediate roll shift in a plurality of stands from the first stand to the last stand one stage before. A method for controlling edge drop during cold rolling. 2. An edge drop of a cold-rolled metal sheet is represented by using, as a plurality of parameters, a difference in sheet thickness with respect to a reference position at a plurality of points having different distances from the sheet edge, and a mathematical model representing these parameters is created in advance. In addition, continuously measure the material profile before rolling or the profile on the exit side of the final stand, and use the measured value as a variable based on the above mathematical model so that the edge drop on the exit side of the final stand matches the target value. In addition, the edge drop improvement amount should always be set by controlling one or more of the work roll bender, the intermediate roll bender, and the intermediate roll shift in a plurality of stands from the first stand to the last stand one step before. A method for controlling edge drop during cold rolling.