JP2005118840A - Plate shape control method in cold rolling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate shape control method in cold rolling for realizing non-interfered control of the plate thickness and the shape by calculating the load/the change quantity of a bender via a model expression. <P>SOLUTION: The crown and the plate thickness are measured on the inlet side of a rolling mill. The plate thickness on the outlet side and the mechanical plate crown are estimated. The tension difference between at the center of the plate width and at the other point is estimated by the model expression prepared in advance. The change in the mechanical plate crown is calculated from the difference between the tension difference and the target value, and the change in plate thickness to achieve the target plate thickness is calculated. The reduction position and the bender position are controlled to control the plate shape so that the change in the mechanical plate crown and the change in the plate thickness are simultaneously the target values, respectively. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention measures the crown on the entrance side of the rolling mill and uses a function model formula that links the tension difference quantitatively representing the plate shape and the rolling conditions, so that the exit side of each rolling mill or each stand exit side of the tandem rolling mill is used. The present invention relates to a plate shape control method in cold rolling, in which a shape is estimated, a rolling condition change amount is calculated from the plate shape, and the plate shape is controlled based on the calculated value.

  The shape change of cold rolling is classified into a short cycle change and a long cycle change. Examples of short cycle changes include shape changes caused by rapid changes in speed and load fluctuations due to short period hardness fluctuations of the original sheet. A long-period change may be paraphrased as a steady-state deviation, and examples thereof include growth of a thermal crown.

It is impossible to compensate for a short period of shape change by feedback control from a sensor such as a shape detector installed on the exit side of the rolling mill. Therefore, there is a technique for detecting and compensating in the rolling mill, and typical techniques include the following.
(1) Detecting the rolling load during rolling and modeling the relationship between the width direction thickness distribution realized when the width direction load distribution between the rolled material and the work roll is uniform, and the rolling conditions There is a technique for correcting the width direction plate thickness distribution by substituting the measured value of the rolling load and calculating the change amount of the bender. This is based on the rolling mill specifications, sheet width, roll shift amount, rolling load, etc., and the influence coefficient of the load of the stand and roll bending force on the plate shape (crown) of the rolled material on the exit side of the rolling mill. This is a technique that calculates and keeps the shape constant according to equation (1).
ΔC = K _CP × ΔP + K _CF × ΔF (1)
Where ΔC is a crown change amount at an arbitrary definition point, K _CP and K _CF are coefficients of influence of rolling load and roll bending force on the crown calculated from the model, ΔP is a change amount of rolling load, and ΔF is roll bending. It is the amount of change in force.
If the shape is good at some point during rolling and there is no need to change the crown, ΔC = 0, so equation (1) can be solved for the rolling load or roll bending force, for example, by some disturbance When the load changes, the shape at a certain point in time can be maintained by changing the roll bending force so as to cancel the influence. Conversely, when the roll bending force changes due to disturbance, the load can be changed so as to cancel the influence. According to this method, since the calculation formula is very simple, it is possible to move the bender almost simultaneously with detecting the change in rolling load, and this method is suitable for short-cycle shape change compensation (see, for example, Patent Document 1). ).
(2) The sheet thickness direction thickness distribution of the rolling material is measured in the longitudinal direction, the target mechanical sheet crown distribution in the longitudinal direction is calculated, and the rolling mill is based on the mechanical sheet crown target value at a certain point that changes from moment to moment. There is also a method of controlling by calculating the operation amount of the control end (see, for example, Patent Document 2).
(3) There is also a method in which a mathematical model representing an elongation difference is created in advance using a material crown or a rolling load as a variable, and the control end of the rolling mill is operated so that the elongation difference matches a target value (for example, patent document) 3).

On the other hand, regarding long-cycle shape change (steady deviation) compensation,
(4) A method of correcting the intermediate roll shift amount, roll bending force, reduction position, etc. via a mathematical model after approximating the plate shape with a quartic function to recognize the plate shape pattern (for example, non-patent document) 1)
(5) A method of correcting the vendor value when the plate shape is disturbed by visual observation by the operator,
(6) When there is a shape detector on the exit side of the rolling mill, a method for quickly compensating the shape by calculating a reasonable operation amount at the control end of the rolling mill based on the output of the shape detector (for example, a patent Reference 4).
JP-A-57-177818 JP-A-10-5837 JP 2002-292414 A Japan Iron and Steel Institute, “Theory and Practice of Plate Rolling”, published on September 1, 1984, p309-312 Japanese Patent Application No. 2002-329084

  With regard to the technique (1) for compensating the short-cycle shape change, when the load changes, it is certainly possible to compensate the change margin by the bender, and the rolling mill exit side shape is a good shape with no steady deviation. There is no problem if it is locked on under such rolling conditions. However, this technique is a technique for operating the control end so as to maintain the current shape, and if it is locked on in a state of being originally rolled into a bad shape, it cannot be made into a good shape. In order to change a defective shape to a good shape by this method, ΔC in equation (1) must be calculated, but there is no means for quantitatively evaluating ΔC at present.

The method (2) of measuring the crown of the material and determining the shape of the mechanical plate crown target value is obtained by analytically calculating the deformation of the rolling mill. However, it is difficult to calculate the manipulated variable directly online because a model formula that links the crown ratio change and the plate shape is not yet developed.
In the method of (3), which matches the elongation difference calculated by the model formula using the material crown and load with the target value, the elongation difference calculated by the model formula and the operation amount of the control end of the rolling mill are rational. Therefore, it is difficult to accurately control the plate and the rolling machine where the change is large, such as the unsteady part.

  Compensation for long-period shape change (steady deviation) has a time delay compared to short-period compensation, but it is desirable to remove the defect as quickly as possible when a defect is found. In that regard, with respect to the above (4), since the amount of change in rolling conditions for calculating the desired shape from the actually measured shape is calculated, it is possible to remove the steady deviation, but it is necessary to repeatedly calculate, so rolling It takes time to modify the conditions, and it is not optimal as an online model. Regarding the monitoring of the operator in (5) above, it is an operation that relies on human senses, and depends on the ability of the individual, and cannot be said to be a technology that can be secured for the future. Further, in the method (6), the output of the shape detector is used to obtain a reasonable operation amount of the control end, so that high precision and relatively fast control is possible. From the point of using the value, there is always a waste time in control, and it is impossible to perform control with a short period.

  As described above, with the conventional technology, it is difficult to remove shape variation with high accuracy in a short period. In recent years, demands on the plate shape of customers have become stricter, and a technology capable of compensating the shape under all conditions is required because cost reduction is essential. Therefore, it is desirable to use a method in which the current shape is estimated and controlled by a control end such as a roll bending force instead of using the output on the rolling mill exit side. In addition, a technique capable of considering the balance between the rolling load and the change in the roll bending force and eliminating the shape variation is necessary so that the plate thickness does not change even when the roll bending force is changed.

  Therefore, the present invention can compensate for a poor plate shape with high response, and directly estimates the amount of change in rolling conditions to obtain a desired plate thickness and shape from the input crown without repeated calculation. A plate shape control method in cold rolling can be provided, which can compensate for irregularities in the plate shape with high accuracy, and therefore can achieve yield improvement and cold rolling at low cost. It is intended to do. According to this technology, it is possible not only to improve the shape of the single stand rolling mill and the final stand exit side, but also to estimate and control the shape between the stands of the tandem rolling mill. It is possible to avoid troubles such as a diaphragm due to a shape defect in the case.

The present invention is to advantageously solve the problems of the conventional methods as described above, and the gist thereof is as follows.
(1) Measure or estimate the sheet crown on the rolling mill or rolling mill group entry side, and use a sheet crown (mechanical sheet crown) realized at least when a uniform load is applied to the entry side plate crown and the roll axis direction. Then, the tension difference at at least one location other than the center of the plate width and the center of the plate width is estimated by the tension difference estimation model formula, and the plate is controlled by the rolling position control and / or the bender control so that the estimated tension difference matches the target value. A plate shape control method in cold rolling, wherein the shape is controlled.
(2) The plate shape control method in cold rolling as described in (1) above, wherein a polynomial relating to a change in crown ratio (C / h-C _H / H) is used as the tension difference estimation model formula.
However, the mechanical plate crown is C, the entry side crown is C _H , the rolling mill exit side plate width center plate thickness is h, and the rolling mill entry side plate width center plate thickness is H.
(3) The plate shape control method in cold rolling according to (1) or (2), wherein the following equation is used as the tension difference estimation model equation.
T = a * (C / h- _CH / H) ² + b * (C / h- _CH / H) + c
Where T is the tension difference. The mechanical plate crown is C, the entry side crown is C _H , the rolling mill exit side plate width center plate thickness is h, and the rolling mill entry side plate width center plate thickness is H. Moreover, a, b, and c are functions of H, h, plate width W, and roll diameter D.
(4) In estimating the tension difference in the cold tandem rolling mill, the mechanical plate crown is estimated for each rolling mill, and the first stand entry side plate thickness is the measured value or the previous thickness as the rolling plate width center plate thickness. Using the estimated value from the process, the measured value or model estimated value is used as the entry side plate thickness after the second stand, the model estimated value is used as the exit side plate thickness, and the measured value is used as the first stand entry side crown. And calculating the crown by the rolling reduction ratio from the measured value of the first stand entry side plate crown for each stand entry side plate crown after the second stand, and estimating the tension difference using the tension difference estimation model formula. The plate shape control method in cold rolling according to (2) or (3) above, characterized in that:
(5) At the same time as calculating the mechanical plate crown at the present time, the target mechanical plate crown is calculated back from the tension difference estimation model formula, and the difference is calculated. Calculate the difference of the thickness target value, and simultaneously determine the mechanical plate crown and the center width of the plate width from the influence coefficient of the load and bender force on the mechanical plate crown and the influence coefficient of the load and bender force on the center plate thickness. The plate shape control method in cold rolling according to any one of the above (1) to (4), characterized in that a reduction position and a bender position are calculated and controlled.

  According to the plate shape control method in the cold rolling of the present invention, it is possible to obtain a rolled material having a good shape with high accuracy, so that it is possible to improve yield, trouble-free plate passing, etc., reduce manufacturing costs, and produce It becomes possible to improve the performance.

  In the present invention, in the cold rolling, from the knowledge that the tension difference and the shape other than the center of the sheet width and the center of the sheet width correspond one-to-one, the disorder of the shape is detected by estimating the tension difference, and the disorder is compensated. To control. It is difficult to compensate for a shape variation caused by a change in rolling conditions with a short period because there is a waste time in the control in the feedback control system based on the output from the shape detector on the delivery side of the rolling mill. To control short-term fluctuations, it is necessary to perform feed-forward control or to perform highly-responsive Fordback control using measurement values such as load cells that have little measurement waste time. In consideration of these points, the present invention has been applied to the above-described prior arts (1), (2), and (4) to create a technique for removing short-term shape variations with high accuracy.

As described above, there has been no means for quantitatively evaluating ΔC in formula (1) when the shape is poor. Further, it is described that the relationship between the change in the crown ratio and the tension is used when obtaining the target value of the mechanical plate crown in the prior art (2). If a model formula is used here, the mechanical plate crown for a desired plate shape is described. It is possible to freely calculate the target value. Meanwhile, there is a control in the plate width central thickness as the operational important parameters, thickness variation Δh is the K _MP influence coefficient of the load on the plate width central thickness, the K _MF in plate width center thickness When the influence coefficient of the bending force exerted is expressed by the equation (2). Here, for the sake of simplicity, the terms of the intermediate roll shift amount and the intermediate roll bending force are omitted, but the same applies if they are added. The same applies to equation (1).
Δh = K _MP × ΔP + K _MF × ΔF (2)
Each influence coefficient of the formula (1) and the formula (2) can be calculated from a model formula or the like, and Δh is calculated from an actual measurement value or a model estimated value by a difference between a target plate thickness and an actual plate thickness. Therefore, if ΔC can be quantitatively evaluated, the amount of change in the load and bending force, that is, the reduction position and the bender position to be set can be known according to the expressions (1) and (2). Solving this binary equation means that both the plate thickness and the crown (shape) are simultaneously set to desired values. Therefore, a means for estimating ΔC is provided.

  In cold tandem rolling, a continuous process in which coils are joined and rolled is the mainstream. When rolling the coil joint, the rolling speed is decreased and accelerated after passing to shift to steady rolling. When the joining portion of the next coil approaches, the state of decelerating again and passing the joining portion is repeated. The coil joint is a so-called unsteady part, and the behavior of the rolling mill is likely to be disturbed, and its influence is likely to appear on the plate thickness and shape. This is because the rolling conditions (for example, the load, the rolling position, the rolling speed, the tension, etc.) are constantly changing at the joint (in the unsteady part), and the behavior of the rolling mill is likely to change. Moreover, since the roll is worn when rolling, it is necessary to replace the roll at an appropriate interval. After the roll exchange, rolling is started, but the behavior of the rolling mill during acceleration is also easily disturbed, which is an unsteady part. In the unsteady portion, if the plate thickness or the shape is largely disturbed, the plate may be broken or squeezed. In this way, it is very important to control the thickness and shape at the unsteady part, but since there are many short-cycle changes in the unsteady part, it is necessary to apply feedback control using the output on the rolling mill exit side. It is effective to use a feedback control method with good responsiveness that estimates and controls the current plate thickness and shape online.

Therefore, a method for estimating the shape online is provided. In the case of cold rolling, there is little width spread, so if there is a load difference in the sheet width direction, the shape on the exit side of the rolling mill appears as an elongation strain difference. If an elongation strain difference occurs in the sheet width direction, a tension difference exists in the sheet width direction, so that the shape and the tension difference can be regarded as one-to-one correspondence. With respect to the tension difference, when the tension difference at the center other than the center of the sheet width and the center of the sheet width is T, T represents a change in the crown ratio (C / h−C _H / H as shown in Equation (3)). ), And the coefficient was found to be a function of the inlet side plate thickness, the outlet side plate thickness, the reduction ratio, and the work roll diameter (FIG. 1). Here, as for the work roll diameter, it is desirable to input each of the upper and lower roll diameters, but if the difference between the upper and lower roll diameters is small, there is no problem even if an average value or a representative value is used.
T = a * (C / h- _CH / H) ² + b * (C / h- _CH / H) + c (3)

  Also, within the cold rolling operation range, the load distribution rarely has two or more extreme values, and the tension difference is unlikely to have a complicated distribution, so the tension at the center of the plate width and one other point When the difference is obtained and approximated to a simple equation of the second or fourth order, the tension difference over the entire plate width can be estimated, and it was confirmed that the difference between the actual tension difference and the estimated tension difference is small. . The tension difference can be expressed in a power form. However, considering the load on the computer, it is desirable to use a polynomial form, so it is expressed in the form of Equation (3). Further, although equation (3) may be a higher order polynomial than the second order for higher accuracy, it should be noted that the load on the computer increases.

  When a uniform load is applied in the roll axis direction, there is no difference in elongation strain at one location other than the center of the plate width and the center of the plate width, so the tension difference T = 0, and at this time, the shape is not disturbed. When an elongation strain difference occurs, the tension difference T increases, and depending on the steel type and material, a restriction is induced when a certain value is exceeded. Therefore, it was investigated how much tension difference occurred from past operation data when throttling occurred. However, the evaluation here is based on the steepness (FIG. 2). The steepness is a value obtained by dividing the wave height by the wave pitch in a state where the plate shape is disturbed and wavy. Assuming that the steepness is a sinusoidal wave, there is no problem in evaluating the shape with the steepness because it corresponds to the tension difference (Japan Steel Association, “Theory and Practice of Sheet Rolling”, 1984 (See September 96, page 96).

  From the survey results, it can be seen that the occurrence of throttling increases sharply when the steepness is 2%. Therefore, it is desirable to set the steepness within ± 2% for the control of the present invention. Furthermore, if there is no restriction in the lower process or the cold rolling process, it is preferable to aim for a steepness of 0%. The presence of plus and minus in the steepness indicates whether the central portion of the plate width is expanded or contracted compared to the plate end. In addition, since the steepness is calculated using the tension difference and the Young's modulus, it should be noted that even if the steepness is ± 2%, for example, the tension difference allowed between the steel plate and aluminum is different.

  By the way, parameters necessary for control by the expression (3) are considered. The entrance side plate width central plate thickness H of the single stand and the tandem rolling mill is measured. In the tandem rolling mill, the inlet side plate thickness after the second stand can be set to the immediately preceding stand outlet side plate thickness. The plate thickness may be measured, or a mass flow estimated value or other mill stretch model estimated value may be used. The entrance crown is based on the measured value on the stand entrance side in the case of a single stand, and on the first stand entrance side in the case of a tandem rolling mill. As a measuring method, a thickness gauge may be scanned in the plate width direction and continuously measured in the longitudinal direction, or a certain point in the width direction may be continuously measured. The value measured after hot rolling may have changed due to pickling, so it is desirable to measure immediately before entering the cold rolling mill, but the crown cannot be measured due to equipment limitations. Alternatively, the measurement value in the above process may be used as it is, or may be estimated based on the measurement value, or the current crown may be estimated by preparing a table value for each plate thickness or plate width, for example. In that case, it is necessary to create a tension estimation model from the measurement value sample of the upper process in advance, or to take control measures such as lowering the control gain in consideration of including an error. In addition, since it is necessary to estimate and control the rolling mill outlet shape at the moment when the estimated crown comes directly under the rolling mill, the time from tracking and measurement point to the rolling mill is estimated considering the rolling speed. Needless to say, it is necessary.

  Further, in order to estimate and control the shape without waste time by a rolling mill, it is necessary to continuously measure the crown that changes every moment. The entry crown after the second stand of the tandem rolling mill can be calculated based on the idea of correcting the rolling crown by the amount of reduction from the measurement crown on the entry side of the first stand. The rolling reduction can be achieved by using the central plate thickness on the stand entry / exit side, and there is no problem if the rolling reduction is constant using the target value in the steady part where there is no significant change, but the entry / exit thickness changes from time to time in the unsteady part. When doing so, it is better to calculate the rolling reduction rate continuously to calculate the entrance crown. It is desirable to use the model estimated value for the outlet side plate thickness in order to minimize the waste time in control. However, since the model estimated value may include a long-period variation such as a thermal crown as an error, it is desirable to add a learning function. Since it seems that there is little fluctuation regarding the plate width, a set value or a value measured in advance may be used. A mechanical plate crown is used as the outlet crown. Since the mechanical plate crown can be calculated by analytically solving the deformation of the rolling mill, the calculation time is short and suitable as an online model. In order to calculate the tension difference that changes from moment to moment online, it is better to calculate with a value that does not include control waste time as much as possible. The mechanical plate crown and the outlet plate thickness may be calculated each time depending on the model, or the reference mechanical plate crown and outlet plate thickness and the influence coefficient of each load / bending force are calculated in advance. It may be calculated as a change amount. If there is a margin in the calculation function, it is desirable to calculate the mechanical plate crown and the outlet side plate thickness at each calculation cycle because it is more accurate. However, it was confirmed that there was almost no error even within the cold rolling operation range even with the method using the influence coefficient.

If the tension difference estimated in this way is within the allowable range, the control may not be performed. However, if the tension difference is out of the allowable range, the reduction position and the bender position need to be changed to be within the allowable range. . The method is described. Since the target value should exist together with the allowable range of the tension difference, the target tension difference = α will be discussed here. Since Equation (3) is a quadratic equation, (C / h-C _H / H) can be calculated. Here, a, b, and c are also functions of the inlet side plate thickness H, the outlet side plate thickness h, the plate width W, and the roll diameter D, where H is a measured value, W is a measured value or set value, and D is when the roll is assembled. The measured value may be used. Since must become tension difference when changing the target thickness is recommended tension difference and for h, can be substituted for the target value h _r. Further, Equation (4) is obtained when the mechanical strip crown of the target at that time and C _{r.
(C r / h r -C H} / H) = β ... (4)
Where β is the solution value.
Equation (5) is obtained by solving this case _{C r.}
C _r = (β + C _H / H) × h _r (5)
Since the current mechanical plate crown C is obtained separately when calculating the tension difference, the value ΔC to be changed can be calculated, and equation (6) is obtained.
ΔC = C−C _r (6)
On the other hand, when the bending force is changed, the load distribution acting between the plate and the work roll is changed, so that the plate width central plate thickness h is also changed. Since the present delivery side plate thickness estimated value h has been calculated, the plate thickness change amount Δh can be calculated and is expressed by the equation (7).
_{Δh = h-h r ... (} 7)

By the way, the influence coefficient of the load / bending force on the mechanical plate crown and the influence coefficient of the load / bending force on the center plate thickness of the plate width can be calculated from the model, and the respective amounts of change can be calculated by the equation (8), (9).
ΔC = K _CP × ΔP + K _CF × ΔF (8)
Δh = K _MP × ΔP + K _MF × ΔF (9)
Where K _CP is the influence coefficient of the load on the mechanical plate crown, K _CF is the influence coefficient of the bending force on the mechanical plate crown, K _MP is the influence coefficient of the load on the plate width center plate thickness, and K _MF is the plate width center. It is the coefficient of influence of bending force on sheet thickness.
Since the amount of change in the mechanical plate crown and the plate width center plate thickness is calculated in this way by the equations (8) and (9), the change amount of the load and bending force can be calculated. The reduction position and the bender position may be changed in consideration of the rigidity. Further, it is desirable to add a learning function in consideration of the influence of a long-period change represented by a thermal crown or the like on the mechanical plate crown or the plate width center plate thickness.

  According to this method, since the measured value on the delivery side of the rolling mill is not used, it is possible to perform on-line control with very little waste time for control. In the above description, the influence of the intermediate roll shift on the crown is not taken into consideration, but if the intermediate roll is changed during rolling, it is desirable to take into account the shape control. The same applies to the intermediate roll bending force.

  The tension difference was estimated online in real time, and shape control was performed using this model. The actual machine 6Hi5 stand tandem cold rolling mill shown in FIG. 3 was used for the test. In the figure, 1a and 1b are work rolls, 2a and 2b are intermediate rolls, 3a and 3b are backup rolls, 4 is a thickness gauge, 5 is a crown gauge, and 6 is a shape gauge. The thickness gauge is an X-ray system and is installed at a distance of 0.5m between the entrance and exit side of the first stand and the exit side of the final stand. An X-ray thickness gauge that can operate at 25 mm from the edge of the plate is always installed, and is used as a crown gauge. A contact-type shape detector is installed at a distance of 1.5 m from the final stand exit side, and continuously measures the thickness and tension difference. The roll dimension is about 420mm in diameter for the upper and lower work rolls, 1600mm for the upper and lower rolls, about 480mm in diameter for the upper and lower rolls, 1600mm for the upper and lower rolls, and about 1100mm in diameter for the upper and lower backup rolls. Not.

  Immediately after the start of rolling, measurement of the entrance side plate width central plate thickness H and the entrance side crown was started. In addition, the influence coefficient of rolling load and roll bending force on the crown and plate thickness was calculated immediately after the start of rolling. The current tension difference is estimated while measuring the load and bending force, and the amount of change in the mechanical plate crown is calculated from the difference from the tension difference target value (this time, modeled at the plate edge and the tension difference target value = 0). At the same time, the plate thickness change amount was calculated from the difference between the current plate thickness estimated value and the target value, and the reduction position and the bender were continuously controlled using equations (7) and (8). Ten coils were rolled continuously, but there was no trouble in passing the plate. The plate thickness was within ± 20 μm over the entire length of the coil, and the steepness was 0.4% on average and 0.8% at maximum.

  Similarly, rolling was performed by a method in which the bending force was manually operated without performing the main shape control and only the plate thickness control was performed. When the investigation was conducted after rolling 10 coils in the same manner as described above, the ratio within ± 20 μm decreased to 97.8% over the entire length of the coil, the steepness averaged 1.1%, and the maximum was 2.3%. It was. This time, the coil was not cut off, but the maximum steepness exceeded 2%, indicating that there was a risk of throttling.

  In the same way, two types of shape control are carried out in the case of using the table value classified by the plate width and thickness as the value of the entry side crown and the measurement crown value of the hot rolled plate. ,evaluated. When the table value is used, the ratio within ± 20 μm is 98.0%, the average of the steepness is 0.75%, the maximum value is 1.7%, and when the crown of the hot-rolled sheet is used, ± 20 μm The ratio was 98.8%, the average of the steepness was 0.77%, and the maximum value was 1.6%. It has been found that sufficient accuracy can be obtained even if the estimated value is used for the entrance plate crown.

It is a figure which shows an example of the relationship between a crown ratio change and a shape parameter. It is a figure which shows the result of having investigated the steepness and the ratio of throttling generation | occurrence | production from the past operation data. It is the schematic of the rolling mill used in the rolling experiment for confirming the effect of a shape control model.

Explanation of symbols

1a, 1b: Work roll 2a, 2b: Intermediate roll 3a, 3b: Backup roll 4: Plate thickness meter 5: Crown meter 6: Shape meter

Claims (5)

Measure or estimate the sheet crown on the rolling mill or rolling mill group entry side, and at least use the sheet crown (hereinafter referred to as mechanical plate crown) realized when a uniform load is applied to the entry side plate crown and the roll axis direction. Then, the tension difference at at least one location other than the center of the plate width and the center of the plate width is estimated by the tension difference estimation model formula, and the plate is controlled by the rolling position control and / or the bender control so that the estimated tension difference matches the target value. A plate shape control method in cold rolling, wherein the shape is controlled. 2. The plate shape control method in cold rolling according to claim 1, wherein a polynomial relating to a crown ratio change (C / h−C _H / H) is used as the tension difference estimation model formula.
However, the mechanical plate crown is C, the entry side crown is C _H , the rolling mill exit side plate width center plate thickness is h, and the rolling mill entry side plate width center plate thickness is H. The plate shape control method in cold rolling according to claim 1 or 2, wherein the following equation is used as the tension difference estimation model equation.
T = a * (C / h- _CH / H) ² + b * (C / h- _CH / H) + c
Where T is the tension difference. The mechanical plate crown is C, the entry side crown is C _H , the rolling mill exit side plate width center plate thickness is h, and the rolling mill entry side plate width center plate thickness is H. Moreover, a, b, and c are functions of H, h, plate width W, and roll diameter D. In estimating the tension difference in the cold tandem rolling mill, the mechanical plate crown is estimated for each rolling mill, and the first stand entry side plate thickness as the rolling plate width of the rolling plate is the measured value or from the previous process. Using the estimated value, the measured value or model estimated value is used as the entry side plate thickness after the second stand, the estimated model value is used as the exit side plate thickness, the measured value is used as the first stand entry side crown, and the second The crown after each stand is calculated so that the crown is changed by the rolling reduction ratio from the measured value of the first crown at the first crown, and the tension difference is estimated by using the tension difference estimation model formula. The plate shape control method in the cold rolling according to claim 2 or 3. At the same time as calculating the current mechanical plate crown, calculate the difference by calculating back the target mechanical plate crown from the tension difference estimation model formula, and calculating the model estimated value or the measured value and the target thickness value of the center plate thickness. To calculate the mechanical plate crown and the center width of the plate at the same time from the influence coefficient of the load and the bender force on the mechanical plate crown and the influence coefficient of the load and the bender force on the center plate thickness. The plate shape control method in cold rolling according to any one of claims 1 to 4, wherein the reduction position and the bender position are calculated and controlled.

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