JPH08238509A - Method for controlling edge drop at time of cold rolling - Google Patents

Abstract

PURPOSE: To control edge drop without lowering operability with high accuracy at the time of cold-rolling a metallic sheet. CONSTITUTION: At the time of controlling the edge drop of the metallic sheet with a rolling mill consisting of plural stands which are provided with controlling means such as work roll benders, intermediate roll benders and intermediate roll shifters, the edge drop of a base stock and/or a rolled stock is expressed by parameters at plural points at different distances from the sheet edge and a numerical formula model in which these parameters are incorporated is preliminarily prepared. The profile of the base stock and the profile of the rolled stock on the outlet side of the final stand are continuously measured during rolling, measured values are substituted for the numerical formula model and one or more of the work roll bender, intermediate roll bender and intermediate roll shifter are controlled or preset so that the edge drop on the outlet side of the final stand is made to coincide with the target value.

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.

In order to solve such a problem, the inventors of the present invention have used an edge of a cold-rolled metal sheet with a plurality of parameters having a difference in sheet thickness from a reference position at a plurality of points having different distances from the sheet edge. A mathematical model representing the drop and these parameters is created in advance, and the material profile before rolling or the profile on the final stand exit side is continuously measured, and the measured value is used as a variable based on the mathematical model to determine the final stand output. One or more of the work roll bender, the intermediate roll bender, and the intermediate roll shift are controlled in a plurality of stands from the first stand to the last stand one stage before so that the edge drop on the side matches the target value. Edge drop control during cold rolling, which is characterized by constantly correcting the edge drop improvement amount. The method was developed (Japanese Patent Application No. 6-214
259). With this control method, the accuracy of edge drop improvement has been greatly improved. However, in this edge drop control method, although the upper limit value is set for the edge drop improvement amount at each stand, the upper limit value of this edge drop improvement amount is empirically set with a margin on the safe side. , The target edge drop may not be obtained.

Particularly, if the edge drop is greatly improved in the front stand, a target edge drop is obtained in a thick gauge steel plate having a product thickness of 1 mm or more, which is apt to cause edge up in a post process in the vicinity of 30 mm from the end. In order to achieve this, it is necessary to take a large amount of edge drop improvement on the stand one step before the final stage, but it often happens that the target edge drop improvement amount cannot be obtained because the upper limit of the edge drop improvement amount is caught. . Therefore, it is important to effectively control the edge drop while preventing breakage by predicting the tension of the plate end that is an index of plate breakage and setting the upper limit of the tension. The present invention is a further improvement of the method proposed in the prior application, in which edge drop is effectively controlled by a work roll bender other than a tapered work roll, an intermediate roll bender, an intermediate roll shift, etc. The object is to obtain a metal plate having excellent uniformity in plate thickness distribution.

[0006]

The present inventor has conducted extensive studies on an edge drop control method incorporating a mathematical model expressing the tension at the plate end, and has completed the present invention. That is, the edge-drop control method of the present invention represents the edge-drop of a cold-rolled metal sheet with a plurality of parameters being the difference in sheet thickness with respect to the reference position at a plurality of positions with different distances from the sheet edge, and these parameters In addition, a mathematical model representing the tension at a position at a predetermined distance from the plate edge from the first stand to the last stand one step before is created in advance, and the material profile before rolling or the profile on the exit side of the final stand is set. Measured continuously, based on the mathematical model with this measured value as a variable,
Within a range in which the tension does not exceed the limit value, the work roll bender in 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 characterized in that the edge drop improvement amount is constantly corrected by controlling one or more of the intermediate roll bender and the intermediate roll shift.

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 expressed 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).

[0010]

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 the} shape control means and the edge drop amounts F _x , F _{y of the} material are changed, the control amounts W _i , I are obtained. _i , δ _i , the edge drop amounts F _x and F _{y 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 _x and E _y . The influence coefficients a ₅ and b ₅ are
It is obtained as a constant term in the relationship.

In 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 relationship 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.

[0013] Here, b _6i is an influence coefficient and is represented by Expression (10). _b6i = _b1i / _a1i ... (10)

In feed-forward control, the material profile before rolling is continuously measured, and equations (1) and (2) are used.
Calculate F _x and F _y from 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, E _x and E _y expressed by the equations (8) and (9) are the target values E _x '
And E _y ′, the edge drop improvement amount S _xi on the exit side of the final stand is determined at a distance x from the plate edge given by the i stand.

If the amount of edge drop improvement in each stand is too large, the shape on the way deteriorates and there is a risk of plate breakage. This is because the tension at the plate edge becomes excessive. Therefore, this plate rupture can be prevented by setting an upper limit value for the tension at the plate end. The tension at the plate end of each stand is the tension T _{i at} a position at a predetermined distance from the plate end.
Evaluate with. In addition, it is desirable that the position of the predetermined distance is close to the plate edge. As shown in FIG. 8, the tension T _i at a position at a predetermined distance from the plate end in each stand has a substantially linear relationship with the edge drop improvement amount S _Xi regardless of the control means. Therefore, the tension T _i can be predicted by the equation (11). T _i = d _1i S _Xi + d _2i ... (11)

In the equation, d _1i and d _2i represent influence coefficients. The influence coefficients d _1i and d _2i 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, the influence coefficient d _1i is constant when all the other rolling conditions are set, and when the edge drop improvement amount S _Xi is changed by changing the control amounts W _1, I _i, δ _i of each shape control means, the edge drop It is obtained as a slope in a linear relationship that is established between the improvement amount S _Xi and the tension T _i at a position at a predetermined distance from the plate end. The influence coefficient d _2i is obtained as a constant term in the relationship. The influence coefficient d _2i changes depending on the profile of the material and the edge drop improvement amount of the stand before the stand.
Since it is smaller than the change amount of the value of the first term in 1), it is set to a constant value.

[0017] Equation (11) the upper limit T _i ^MAX provided from plate end shown in tension T _i of position at a predetermined distance, the tension T _i is edge drop improvement so as not to exceed the upper limit value T _i ^MAX By constantly correcting the amount S _Xi , plate breakage can be prevented. The upper limit value T _i ^MAX is set to the deformation resistance level of the rolled material. If the target values E _x 'and E _y ' of the edge drop cannot be obtained by setting the upper limit value T _i ^MAX , equation (12)
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') (12) wherein, W _x, W _y represents a weighting coefficient. When the target values E _x 'and E _y ' of the edge drop are obtained on a rolling mill with four or more stands, the edge drop improvement amount S at each stand is S.
Any combination of _xi can be adopted. However, considering the shape in the middle, it is possible to introduce the evaluation function J ₂ as shown in Expression (13) and constantly correct the edge drop improvement amount S _xi in each stand so that the evaluation function J ₂ is minimized. preferable.

[0018] 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 are as follows.
It can be set in any combination. 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. Further, although the edge drop on the delivery side of the final stand is expressed by E _x and E _y shown in the formulas (3) and (4), it can be expressed by incorporating E _z shown in the formula (14). Further, E _{z in} Expression (14) can be expressed by Expression (16) from the relationship of Expression (15).

[0019]

In the equation, c _6i represents an influence coefficient, and the following equation (1
It is represented by 7). _{c 6i = c 1i / a 1i} ···· (17) also has an evaluation function J ₃ represented by the following formula (18) 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 (18) 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 equation according to the following equations (19) and (20) is used.

[0021]

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 correction amount of 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 equations (3) and (4) from the profile on the exit side of the final stand, which are continuously measured, respectively, and equations (21) and (2
2). E _x ¹ = h _k ¹ −h _x ¹ ... (21) E _y ¹ = h _k ¹ −h _y ¹ ... (22) where h _x ¹ , h _y ¹ and h _k ¹ Indicates the plate thickness on the delivery side of the final stand at the distances x, y and k from the plate edge measured continuously. 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 the following equations (23) and (2
4).

[0023]

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 the equations (21) and (22), and the equations (23) and (24) 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 2) 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 Expression (13) 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.

[0025]

[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. 9, 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 improved forms of edge drop are different 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.

Further, in the present invention, a mathematical model expressing the tension at the plate end is created, and an upper limit value of the tension is provided to improve the edge drop so that the tension at the plate end does not exceed the upper limit value. The edge drop can be effectively controlled within the range where plate breakage does not occur. 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. Corresponding to this, as a control for correcting the control amount of each shape control means during rolling, feedforward control and / or
Or there is feedback control. 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. The method of controlling the edge drop within the range in which the tension does not exceed the limit value based on the mathematical model representing the tension at a position at a predetermined distance from the plate edge that constitutes the present invention uses a tapered work roll. It goes without saying that the edge drop control can also be used.

[0028]

【Example】

Examples 1 and 2 (Feedforward Control) In Japanese Patent Application No. 6-214259, which was previously invented by the present inventors, because of the upper limit of the edge drop improvement amount, there were few cases where the target edge drop could not be obtained. Cold-rolled steel sheet having a plate thickness of 0.5 mm (Example 1) Rolling of a cold-rolled steel sheet having a plate thickness of 1.5 mm (Example 2), which was often the case where a target edge drop was not obtained, according to the present invention. The method is compared with the method according to Japanese Patent Application No. 6-214259.
In this example, a tandem rolling mill 5 provided with four stands 1 to 4 as shown in FIG. 10 was used. The rolling conditions are input to the host computer 6 and the process computer 7 inputs N
o. The optimum amount of edge drop improvement in the 1 to 3 stands was calculated and input to the shape control means 8. In addition, the X-ray plate thickness meter 9 movable in the plate width direction is used to measure the steel plate 10 being rolled.
The profile before rolling was continuously measured, and the measured values were imported into the host computer 6. Process computer 7
Then, the optimum edge drop improvement amount is calculated based on the actual measurement 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 = 10 mm was set. Also,
When the edge drop is controlled and reduced, edge-up, which is a problem in the post-process, is likely to occur in the vicinity of 30 mm from the plate edge, so y = 30 mm was set. Under the rolling conditions of the present example, the range in which the plate thickness does not change due to the edge drop control is on the center side in the plate width direction from 50 to 100 mm from the plate end, so the reference point for edge drop amount evaluation is k = 1.
It was set to 00 mm.

The edge drop of the material is defined by F ₁₀ and F ₃₀ shown in equations (25) and (26), and the edge drop on the delivery side of the final stand is E ₁₀ and E ₃₀ shown in equations (27) and (28). Defined in. _{F 10 = H 100 -H 10 ····} (25) F 30 = H 100 -H 30 ···· (26) E 10 = h 100 -h 10 ···· (27) E 30 = h 100 -h ₃₀ · · · · (28) E ₁₀ and E ₃₀ is represented by each formula (29) and (30). The material profile before rolling was continuously measured by the X-ray plate thickness gauge 9 so that E ₁₀ and E ₃₀ were the target values E ₁₀ ′ and E ₃₀ ′, respectively, and F was calculated according to the equations (25) and (26). Calculate ₁₀ and F ₃₀ . Then, the edge drop improvement amount S _10i on the delivery side of the final stand at a distance of 10 mm from the plate end given by No. 1 to 3 stands is given by the following equation (2)
It was constantly corrected according to 9) and (30).

[0030]

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 T _i of the tension T _{i at} the distance of 10 mm from the plate end in each stand represented by the formula (31) for each product type. ^MAX was set to the deformation resistance value of the rolled material. T _i = d _1i S _10i + d _2i (31) The target value E of the edge drop depending on the setting of the upper limit value T _i ^MAX.
_{When 10} ′ and E ₃₀ ′ are not obtained, the evaluation function J ₁ shown in Expression (32) is introduced, and the edge drop improvement amount S _10i in each stand is corrected 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 ... (32) 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.
Considering the adverse effect of the shape on the way, the evaluation function J ₂ of Expression (33) 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.

[0032]

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 11
Is a flow showing the procedure described above. Regarding the cold rolled steel sheet having a product sheet thickness of 0.5 mm (Example 1), the actual values of the edge drop are compared with the target values E ₁₀ ′ and E ₃₀ ′, and the results are shown in FIGS. 12 and 13. In addition, Japanese Patent Application No. 6-214259
The actual values of edge drop by the method of No. ₁₀ are shown in FIGS. 14 and 15 in comparison with the target values E ₁₀ ′ and E ₃₀ ′.
In both the method according to the present invention and the method according to Japanese Patent Application No. 6-214259, the actual value of the edge drop is the target value E ₁₀ 'and E.
It is within ± 5 μm with ₃₀ 'as the reference, and it can be seen that the edge drop is improved with high accuracy. For the cold rolled steel sheet having a product sheet thickness of 1.5 mm (Example 2), the actual value of the edge drop was compared with the target values E ₁₀ 'and E ₃₀ ',
This is shown in FIGS. 16 and 17. In addition, Japanese Patent Application No. 6-214259
The actual value of edge drop by the method of No. is the target value E ₁₀ '
And E ₃₀ ', as shown in FIGS. 18 and 19.

In the method of Japanese Patent Application No. 6-214259, the upper limit value S _10i ^{M AX} of the edge drop improvement amount is set on the safe side with a margin, so that the edge drop at the position 10 mm from the plate edge The actual value is the target value E ₁₀ '
On the plus side with respect to, the range exceeds +5 μm.
On the other hand, when controlled according to the present invention, 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. 16 and 17. It can be seen that the edge drop is improved with high accuracy. In rolling cold-rolled steel sheet having a product sheet thickness of 0.5 mm and cold-rolled sheet metal sheet having a product sheet thickness of 1.5 mm, both the method according to the present invention and the method according to Japanese Patent Application No. 6-214259 are used to measure the tension in each stand. Since the upper limit value T _i ^MAX and the upper limit value S _10i ^MAX of the edge drop improvement amount are set,
Breakage due to deterioration of the shape on the way is also prevented. As a result, No. Since the shape control was performed without edge drop control in the 4-stand, a product having a good shape was obtained.

Example 3 (feedback control) In the method of Japanese Patent Application No. 6-214259 previously invented by the present inventors, since the upper limit of the edge drop improvement amount,
Feedback control was performed on rolling of a cold rolled steel sheet having a product sheet thickness of 1.5 mm, which was often the case where a target edge drop was not obtained. In this embodiment, No. 4 X on the exit side
With the same equipment configuration as in FIG. 10 except that the line plate thickness gauge 9 is arranged,
o. The profile of the steel plate 10 during rolling on the delivery side of the four stands was continuously measured by an 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 as in the first and second embodiments.
mm, y = 30 mm and k = 100 mm, No.
4 The edge drop on the outlet side is expressed by the formulas (34) and (3
It is represented by E ₁₀ and E ₃₀ defined in 5). _{E 10 = h 100 -h 10 ····} (34) E 30 = h 100 -h 30 ···· (35) E 10 and E ₃₀ is represented by each formula (36) and (37) . The profile on the exit 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 were the target values E ₁₀ ′ and E ₃₀ ′, respectively, and the formula (38) was used. and to calculate the E ₁₀ ¹ and E ₃₀ ¹ in accordance with (39). Then, the correction amount ΔS _10i of the edge drop improvement amount S _{10i on} the _delivery 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 (36) and (37).

[0037]

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 T _i of the tension T _{i at} the distance of 10 mm from the plate end in each stand represented by the formula (40) for each product type. ^MAX was set to the deformation resistance value of the rolled material. T _i = d _1i S _10i + d _2i (40) When the target values E ₁₀ 'and E ₃₀ ' of the edge drop cannot be obtained by setting the upper limit value T _i ^MAX , the evaluation function J shown in the equation (41) ₁ was introduced and the correction amount ΔS _10i of the edge drop improvement amount S _10i in each stand was constantly set so that the evaluation function J ₁ was minimized. _{J 1 = w 10 (E 10} -E 10 ') 2 + w 30 (E 30 -E 30') 2 ···· (41) weighting coefficients w ₁₀ and w ₃₀ in the formula, each w ₁₀ = 1 and w ₃₀ = 2. Target value of edge drop E ₁₀ 'and E
_{When 30} 'is obtained, an arbitrary 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 (42) can be used. 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

[0039]

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. 21 and 22. As shown in FIGS. 21 and 22, 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. In addition, the upper limit T of tension at each stand for each product type
_Since ^iMAX is set, 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.

Example 4 (Preset control) In the method of Japanese Patent Application No. 6-214259 previously invented by the present inventors, since the upper limit value of the edge drop improvement amount,
Rolling of cold-rolled steel sheet having a product sheet thickness of 1.5 mm, which was often the case where the target edge drop was not obtained, was preset controlled. In this embodiment, the tandem rolling mill 5 including the four stands 1 to 4 having the equipment configuration shown in FIG. 23 was used, and the edge drop information of the material and the rolling conditions were input to 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 =
E is set to 30 mm and k = 100 mm, and the edge drop on the exit side of the final stand is shown in equations (43) and (44).
_10, defined in the E _{30. E 10 = h 100 -h 10 ····} (43) E 30 = h 100 -h 30 ···· (44) E 10 and E ₃₀ is represented by each formula (45) and (46) . 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.

[0042]

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 T _i of the tension T _{i at} the distance of 10 mm from the plate end in each stand represented by the formula (47) for each product type. ^MAX was set to the deformation resistance value of the rolled material. T _i = d _1i S _10i + d _2i (47) Target value E of edge drop depending on setting of upper limit value T _i ^MAX
_{When 10} ′ and E ₃₀ ′ are not obtained, the evaluation function J ₁ shown in Expression (48) 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 (48) 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 (49) was introduced in consideration of the adverse effect of the shape on the way, and the edge drop improvement amount S _10i at each stand was determined so that the evaluation function J ₂ was minimized.

[0044]

FIG. 24 is a flow chart showing the procedure described above. The actual value of the edge drop is compared with the target values E ₁₀ ′ and E ₃₀ ′ and shown in FIGS. 25 and 26. 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. 25 and 26, and the edge drop is improved with high accuracy. I understand. Further, since the upper limit T _i ^MAX of the tension in 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.

[0046]

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

FIG. 9 is a comparison diagram of a work roll bender, an intermediate roll bender, an intermediate roll shift, and a tapered work roll shift in relation to the edge drop improvement amount and the tension near the plate edge.

FIG. 10: Tandem rolling mill used in Examples 1 and 2

FIG. 11 is a flow chart showing the procedure in the first and second embodiments.

FIG. 12 is a comparison between the actual value of the edge drop and the target value E ₁₀ ′ in the first embodiment.

FIG. 13 is a comparison between the actual value of edge drop and the target value E ₃₀ 'in Example 1.

FIG. 14: Comparison between the actual value of the edge drop and the target value E ₁₀ ′ in the method of Japanese Patent Application No. 6-214259 (cold rolled steel sheet with a product sheet thickness of 0.5 mm)

FIG. 15: Comparison between the actual value of edge drop and the target value E ₃₀ ′ in the method of Japanese Patent Application No. 6-214259 (cold rolled steel sheet with a product sheet thickness of 0.5 mm)

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: Comparison between the actual value of the edge drop and the target value E ₁₀ ′ in the method of Japanese Patent Application No. 6-214259 (cold rolled steel sheet with a product sheet thickness of 1.5 mm)

FIG. 19: Comparison between the actual value of the edge drop and the target value E ₃₀ ′ in the method of Japanese Patent Application No. 6-214259 (cold rolled steel sheet with a product sheet thickness of 1.5 mm)

FIG. 20 is a flowchart showing the procedure in the third embodiment.

FIG. 21: Comparison between the actual value of edge drop and the target value E ₁₀ 'in Example 3

22 is a comparison between the actual value of edge drop and the target value E ₃₀ 'in Example 3. FIG.

FIG. 23: Control mechanism of tandem rolling mill used in Example 4

FIG. 24 is a flow chart showing the procedure in the fourth embodiment.

FIG. 25: Comparison between the actual value of edge drop and the target value E ₁₀ 'in Example 4

26 is a comparison between the actual value of edge drop and the target value E ₃₀ ′ in Example 4. FIG.

[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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaki Otsuka 5th Ishizu Nishimachi, Sakai City, Osaka Prefecture Sakai Works (72) Inventor Junya Hayakawa 5th Ishizu Nishimachi, Sakai City, Osaka Nisshin Steel Co., Ltd. Sakai Factory

Claims (3)

[Claims] 1. An edge drop of a cold-rolled metal sheet is represented by a plurality of parameters, which are differences in plate thickness from a reference position at a plurality of points having different distances from the sheet edge, and these parameters and the first stand are used to determine the edge drop. A mathematical model representing the tension at a position at a predetermined distance from the plate edge to the stand one step before is created in advance, and the material profile before rolling or the profile on the delivery side of the final stand is continuously measured. From the first stand to the last stand one step before, so that the edge drop on the exit side of the final stand matches the target value, within the range where the tension does not exceed the limit value, using the measured value as a variable, based on the mathematical model. By controlling one or more of the work roll bender, the intermediate roll bender, and the intermediate roll shift on multiple stands of the An edge drop control method during cold rolling, which constantly corrects the edge drop improvement amount. 2. An edge drop of a cold-rolled metal sheet is represented by a plurality of parameters, which are differences in sheet thickness with respect to a reference position at a plurality of points having different distances from the sheet edge, and these parameters and the first stand are used to determine the edge drop. A mathematical model representing the tension at a position at a predetermined distance from the plate edge to the stand one step before is created in advance, and the material profile before rolling or the profile on the delivery side of the final stand is continuously measured. From the first stand to the last stand one step before, so that the edge drop on the exit side of the final stand matches the target value, within the range where the tension does not exceed the limit value, using the measured value as a variable, based on the mathematical model. By controlling one or more of the work roll bender, the intermediate roll bender, and the intermediate roll shift on multiple stands of the An edge drop control method during cold rolling, which is characterized by constantly setting an edge drop improvement amount. 3. An edge drop is controlled within a range in which the tension does not exceed a limit value, based on a mathematical model expressing tension at a position at a predetermined distance from the plate edge from the first stand to the last stand one step before. An edge drop control method at the time of cold rolling.