JP4268582B2 - Plate thickness control method and plate thickness / shape non-interference control method - Google Patents

Description

  The present invention is a sheet thickness / shape control method focusing on the vicinity of a joint for minimizing off-gauge in rolling including a joint including cold tandem rolling, and further, so-called stable rolling is difficult similarly to the joint. The present invention relates to a method for controlling the thickness and shape of the unsteady portion. Here, the unsteady part is the vicinity of the hot-rolled joint, immediately after biting of the hot-rolling, immediately before the tail end of the tail end, immediately after the start of rolling after changing the roll of cold-rolled, or unstable such as gauge hunting Represents when rolling.

  In cold tandem rolling, a method of joining coils and continuously rolling them is common. In recent years, the hot rolling has been continued. The demand for high-precision sheet thickness continues to rise, and the control in the vicinity of the joint is the same for both hot rolling and cold rolling. However, many mills perform cold rolling regardless of steel type. Since the demand is great in rolling, the rest of this section will mainly describe cold rolling. In cold tandem rolling, in recent years, not only the steady portion where rolling is stable, but also the demand for improving the plate thickness accuracy of the unsteady portion is increasing. There are various control systems in cold tandem rolling depending on the thought of the mill at the time when it was assembled, but the first stand performs the reduction control, and the first and subsequent stands perform the tension control that changes the roll peripheral speed. There are many. In many cases, the first stand is added with tension control for changing the roll peripheral speed based on the output of the thickness gauge installed on the exit side of one of the subsequent stages. A schematic diagram is shown in FIG. 1 as an example of a general plate thickness control system. In FIG. 1, the gauge meter AGC is applied to the first stand, and the tension AGC based on the output of the thickness meter on the exit side of the final stand is applied to all the stands. In FIG. 1, 1a and 1b indicate work rolls, 2a and 2b indicate intermediate rolls, and 3a and 3b indicate backup rolls. 4 is a rolled material, 5 is a thickness gauge, and 6 is a mill motor. Further, 7 is a load detector, 8 is a hydraulic pressure reducing device, 9 is a tension meter, and 10 is a bender.

For the first stand, a relative value gauge meter AGC such as BISRA-AGC or mass flow AGC is mainly used. In these plate thickness controls, there are a method of estimating the plate thickness itself and obtaining the difference Δh from the target plate thickness, and a method of obtaining Δh as the difference between the reference plate thickness and the current plate thickness estimated value. Basically, the reduction position is controlled so that the obtained Δh is zero. PI control as shown in FIG. 2 is often used in the plate thickness control as a control for compensating for the deviation of Δh. Therefore, hereinafter, PI control will be described. A deviation at time t and e (t), proportional gain _{K P,} and an integral gain _{K I} control amount u (t) is expressed by Equation (1).

K _P and K _I are set so that the stability in control is not impaired and at the same time, the deviation is eliminated quickly, and both are usually smaller than 1. Furthermore, as an actual control amount, a control gain α is often multiplied to obtain a reduction position change amount ΔS = αu (t). α is sometimes called a scale factor. The above-described contents are the same for, for example, P control, I control, PID control, and the concept is the same for modern control.

  A control gain is usually created with a table based on a constant value, steel type, size, etc., and a value based on the table is used. However, as in Patent Document 1, a part of the control gain is focused on a low frequency component such as a skid mark by hot rolling. There are also a method of changing the gain and a method of setting the gain using a fuzzy rule from a change in the ratio of the inlet side plate thickness deviation and the outlet side plate thickness deviation as in Patent Document 2.

  Further, as measures for improving the plate thickness accuracy of the unsteady portion, Patent Documents 3 to 7 disclose methods for increasing the plate thickness by changing the tension and the reduction position from the intermediate stand to the final stand.

  Up to now, the thickness control by the absolute value gauge meter AGC has been performed in a hot-rolling finishing stand or the like. In order to apply the absolute gauge meter AGC, a high-precision mill stretch model for accurately grasping the increment of the gap between the upper and lower work rolls due to elastic deformation of the rolling mill called mill stretch is required. A technology related to the basic configuration and basic usage is disclosed. Patent Document 9 discloses a technique related to a sheet thickness control method using an influence coefficient by calculating an influence coefficient of a rolling load and a roll bending force from this model only when this model is used in hot rolling. Has been.

  Patent Document 10 discloses a plate thickness / shape non-interference control technique using an influence coefficient of a load and a bending force on a plate thickness and a crown amount. It is sufficient if the mill stretch amount can be calculated for each AGC cycle. However, in a control that requires high responsiveness such as an absolute value gauge meter AGC, it is difficult to calculate the stretch amount in real time and reflect it in AGC from the viewpoint of calculation time. A technique using an influence coefficient is generally applied.

Also, when roll-down control using a gauge meter type is performed, roll eccentricity may become a problem, and various inventions have been made for roll eccentricity control, but as in Patent Documents 11 and 12 A method of compensating based on frequency analysis from the roll rotation is mainly used, and there are many applications for different detection means, analysis means, and control means.
JP-A-5-261419 JP-A-5-31516 JP-A-5-123725 JP 5-123726 A JP-A-5-123727 JP-A-5-123728 JP-A-6-12631 JP-A-60-30508 JP-A-6-285525 JP-A-57-177818 Patent 19870824 JP 2003-80305 A

  As disclosed in Patent Documents 1 and 2, the method of setting the control gain from the skid mark and the input / output side plate thickness deviation is effective for plate thickness control, but the system is complicated to change the control gain in various ways depending on conditions. The point is. One reason why many types of control gains must be applied is that it is difficult to accurately estimate the thickness immediately below the roll tool. In particular, when the plate thickness in the vicinity of the joint changes in a short cycle, accurate estimation of the plate thickness immediately below the roll bite is the mass flow AGC and BISR AGC that are often used as a cold rolling reduction control method. Monitor AGC is impossible for the following reasons, and it is difficult to set the control gain, proportional gain, and integral gain high.

  In the mass flow AGC, the first stand outlet side plate thickness can be estimated from the mass flow constant law if an inlet side plate thickness meter, an inlet / outlet plate speed meter, or a measuring device equivalent thereto is provided. However, the data of the thickness gauge installed in the mill includes the influence of filters, etc., and it is difficult to capture the abrupt change when there is a sudden change in the thickness of the joint. . In addition, since the plate thickness changes sharply, tension fluctuations also occur. For example, in the case of a plate speedometer such as a pulse generator, it is questionable whether an accurate speed can be measured. Even if the estimated plate thickness is accurate, if the tracking is not accurate, it is difficult to change the reduction position when the portion comes directly under the mill. From the above situation, it is difficult to set the control gain high in the mass flow AGC.

  BISRA AGC is a method in which a mill constant is obtained in advance, lock-on is performed under a certain rolling condition, and the reduction position is compensated according to a load change from the rolling condition. Since the absolute value of the plate thickness cannot be estimated, when the lock-on plate thickness deviates from the target plate thickness, it cannot be controlled to the target plate thickness. Therefore, it is indispensable to use together with the monitor AGC using a sheet thickness meter on the delivery side of the rolling mill. It is possible to estimate the thickness of the next coil as an absolute value based on the information of the previous coil if it is the same steel type, the same width, and the same thickness on both the input and output sides. Rolling with continuous sheet width is frequently performed, and the mill stretch cannot be estimated in absolute values for rolled materials that differ by any one of steel grade, sheet thickness, and sheet width before and after the joint. It is impossible to estimate the thickness as an absolute value. From the above situation, it is difficult to set the control gain high in BISRA AGC.

  Next, since the monitor AGC is controlled using the output of the thickness gauge installed on the stand exit side, it cannot be controlled for steep variations in thickness near the joint, and the control gain is Difficult to set high.

  In either case, since the estimated value of the outlet side plate thickness cannot be said to be sufficiently accurate, there is a problem that the control gain cannot be increased and high-precision plate thickness control is impossible in the first stand. The same applies when the control gain in the above sentence is replaced with a proportional gain, an integral gain, or a combination thereof.

  Prior art patent documents 3 to 7 are cited as plate thickness control techniques in the vicinity of the joint, and when rolling a material having a hardness variation such as in the vicinity of the joint, the plate in the intermediate stand is used. A method of correcting the thickness variation using the first stand and the second stand from the final stand is disclosed. This method is characterized in that the control is performed by paying attention to the plate thickness on the exit side of the final stand, and this control can completely eliminate the variation when considering variations in the plate thickness, tension, etc. near the joint. Difficult and there is room for improvement.

  Patent Documents 8 to 10 disclose a calculation method of a high-precision mill stretch model used for an absolute value gauge meter AGC and a method for using the same. Since this technology can estimate the plate thickness directly under the roll tool with high accuracy, it is considered to be the best plate thickness estimation method at present.

  Patent Documents 11 and 12 disclose roll eccentricity control technology. Regardless of the relative value gauge meter AGC or the absolute value gauge meter AGC, when the gauge meter AGC is used, roll eccentricity may be a problem, and these eccentricity control techniques are effective. However, the frequency analysis method has practically difficult points such as requiring a detecting means for the backup roll and difficult to match the timing accurately.

  Further, although the control gains are disclosed in Patent Documents 1 and 2, neither of the above methods discloses a method for individually changing the proportional gain and the integral gain as necessary.

  In consideration of these points, the present invention can obtain high-precision plate thickness / shape control not only in the steady portion but also in the unsteady portion only by changing the software without distinguishing between cold rolling, hot rolling, and thick plate. It is an object.

The present invention is for solving the problems of the conventional methods as described above,
(1) In continuous rolling performed by joining a preceding material and a succeeding material, the sheet thickness is estimated based on a mill stretch model used for an absolute gauge meter AGC in a rolling mill having a load detection means and a reduction position correction means. The plate thickness control gain, proportional gain, and integral gain in any fixed section of the unsteady portion are set to one or more from the steady portion so that the target value and the estimated value of the plate thickness of the unsteady portion coincide with each other. A plate thickness control method comprising correcting the reduction position by increasing.
(2) In continuous rolling performed by joining the preceding material and the succeeding material, the influence coefficient and the bending force of the load on the sheet thickness in advance by a rolling mill having a load detecting means, a bending force detecting means, a reduction position correcting means and a bender. The influence coefficient of the load and the influence coefficient of the bending force on the mechanical plate crown at an arbitrary definition point are calculated, and the target value and absolute value of the unsteady part thickness are calculated using these four influence coefficients. Any one or more of control gain, proportional gain, integral gain for plate thickness control in an arbitrary constant section of the unsteady part so that the estimated value based on the mill stretch model used for the value gauge meter AGC matches. Is increased from the steady part to correct the reduction position, and the control gain and proportional gain for shape control in any fixed section of the unsteady part Thickness and shape decoupling control method characterized by operating the vendor as one of the integral gain or two or more increases than the steady section to compensate for the mechanical strip crown variation.
(3) In the invention of (2) , an estimation plate based on a mill stretch model used for a detection plate thickness and an absolute value gauge meter AGC in a stationary part, having plate thickness detection means and shape detection means on the stand exit side Comparing the thickness and comparing the detection shape of an arbitrary defined point with a predetermined target shape, based on the difference between the plate thickness detection value and the plate thickness estimation value, and the difference between the shape detection value and the shape target value Furthermore, the rolling position and bending force are further corrected using the influence coefficient of the load and the bending force on the plate thickness and the influence coefficient of the load and the bending force on the mechanical plate crown at an arbitrary defined point. A plate thickness / shape non-interference control method characterized by correcting an estimated plate thickness.

According to the first invention, since the gain is set to be large in the unsteady portion where the plate thickness largely changes, it becomes possible to control the target plate thickness in a short time. If the gain is too large in the steady portion, there is a concern about the influence of roll eccentricity. Furthermore, since the present gain has sufficient plate thickness control accuracy , there is no need to increase it forcibly. As a result, high-precision plate thickness control can be performed not only in the steady portion but also in the unsteady portion.

According to the second invention , since the thickness and shape are estimated and controlled using the influence coefficient, the load on the computer is small and high-speed calculation is possible, so the thickness and shape can be controlled with high accuracy online. Suitable for doing. The effect of changing the gain is the same as in the first aspect of the invention, and the higher the calculation is possible in the unsteady part, the more accurate control becomes possible. Therefore, the present invention can be used in the unsteady part in addition to the steady part. The plate thickness and shape can be controlled. In addition, since the influence of the correction of the reduction position on the plate thickness / shape and the correction of the vendor interfere with each other, the reduction amount of the reduction position and the vendor correction amount are simultaneously obtained from the amount of change of the plate thickness and the amount of change of the shape. Therefore, a significant effect can be obtained by controlling without causing interference.

According to the third aspect of the invention , it is possible to increase the accuracy of the plate thickness and shape by taking into account the influence of factors that change over time that are not included in the model. In other words, it means that the thermal crown and wear grow when the roll is rolled, and the influence is taken into consideration. Since the estimated plate thickness error can be corrected to the target value in the stable part of the steady-state control, and the shape can be changed to the preset target value, it is compared with the case without the present invention. This improves the thickness and shape control accuracy. The point which obtains a significant effect by performing non-interference control of plate thickness and shape is the same as that of the 2nd invention .

  As described above, according to the plate thickness / shape control method of the present invention, the effect can be expected only by changing the software. It is possible to improve the yield and reduce the cost. Further, the application of the present invention can be expected not only for cold rolling tandem rolling mills but also for single stand rolling mills, hot rolling and thick plate rolling.

  In cold tandem rolling, continuous rolling is performed by welding on the mill entry side, regardless of the steel type. FIG. 1 shows a four-stand tandem rolling mill as an example. As shown in the example of FIG. 1, the plate thickness control is generally a reduction control in the first stand, and in particular, a mill having a hydraulic reduction. In this case, the reduction position can be changed in a short cycle, so that high-precision control is possible. In the plate thickness control, as described above, the amount of the difference Δh between the target plate thickness and the estimated plate thickness is not changed, but the control amount calculated by using the proportional gain / integral gain is multiplied by the control gain α. To change the value. The control gain and the proportional / integral gain are determined in consideration of the fact that the deviation is quickly eliminated when there is a deviation while maintaining the stability of the control system.

  The control gain will be described below in the gain, but the concept is the same for the integral gain and the proportional gain. If α = 1, the calculated control amount is changed as it is, but is usually set to a value of 1 or less in consideration of the stability of the system. In cold tandem rolling, there are two major control ranges for control purposes. That is, a stationary part and an unsteady part.

  As described above, the unsteady portion is a portion where the plate thickness changes abruptly as represented by about 10 m before and after the vicinity of the joint portion, and the non-steady portion also when the plate thickness suddenly changes in a short cycle other than the joint portion. Included. The concept is the same for the shape. The stationary part is the other part. Since the change is originally small in the steady portion, the thickness deviation Δh itself is small, and it is not necessary to change the reduction position or the like so much. In that case, it is not necessary to increase the control gain. Since a sudden change occurs in the unsteady portion, it is necessary to greatly change the reduction position. In particular, if the time delay is so small that it does not cause a problem in control, and the plate thickness directly under the roll tool can be accurately estimated, it is preferable to take a large control gain and quickly remove the deviation to converge. That is, as shown in FIG. 3, it is preferable to detect the unsteady part set in advance by tracking and change the control gain.

  Here, the problem is whether or not the plate thickness can be accurately estimated in a state where there is almost no time delay, but the absolute value gauge meter AGC using the gauge meter formula introduced in Patent Documents 8 to 10 in the prior art. The inventors have obtained as knowledge that the sheet thickness can be accurately estimated in a range of ± 0.5% in cold rolling by applying the above. Since there is almost no time delay in this control method, the control gain may be increased.

  Therefore, using this control method, an experiment was conducted to increase the control gain near the joint. For rolling, plain steel with a plate width of 100 mm was rolled using a 4Hi single stand laboratory rolling mill. The leading material was reduced from 3.2 mm to 2.1 mm, and the trailing material was reduced from 4.2 mm to 3.5 mm. For comparison, control by BISRA AGC / mass flow AGC was also performed. The result of comparing the on-gauge rates is shown in FIG. Here, the on-gauge rate was calculated by setting the on-gauge range to ± 1.5% of the target plate thickness. The contents of the experiment are also described below, but the rolling conditions are the same in the following, and only the changes are described.

  The absolute gauge gauge AGC can be used to accurately estimate the thickness just below the roll bite, so increasing the control gain will greatly improve the on-gauge rate. However, with BISRA AGC, the thickness just below the roll bite should be accurately estimated. However, it was confirmed that when the control gain is increased, the on-gauge rate is improved up to a certain point, but it gets worse when the control gain is increased. In other words, it was confirmed that if a plate thickness control method that can be accurately estimated is used, there is an effect of increasing the control gain. The mass flow AGC has an effect close to that of the absolute value gauge meter AGC if there is no tracking failure. However, when there is a tracking failure, it has been found that it is better to decrease the control gain rather than increase it. Note that it is difficult to accurately specify the position of a rolled material that extends in the rolling direction during rolling, and it is still difficult to perform tracking with high accuracy. Here, tracking with high accuracy means that the tracking is accurately performed in units of several millimeters. In the present invention, the set length of the unsteady portion is considered at a level of about 10 m, so the above-described tracking is performed. There is no problem in the unsteady part determination by.

  Regardless of whether the control method is a relative value gauge meter AGC or an absolute value gauge meter AGC, when the gauge meter AGC is used, the roll eccentricity works in a direction in which the plate thickness is estimated in the reverse direction. Care should be taken if there is. In recent years, the effect of roller bearings has been reduced, but it is necessary to take measures because oil film bearings still remain and the core may be slightly displaced depending on the roll polishing method. As for roll eccentricity, a method of compensating in synchronization with the rotation cycle of the backup roll is the mainstream, but even this method cannot be completely eliminated. Therefore, since it is not necessary to change the reduction position significantly in the steady portion, a method of increasing only the gain of the unsteady portion while keeping the control gain at the current small value on the assumption that roll eccentricity occurs. It is good to take.

  Table 1 shows the result of changing the control gain using the above-mentioned lab mill. When oil film bearings are used as a backup roll and rolling is performed using an absolute value gauge meter AGC in a situation where roll eccentricity is likely to occur, the control gain switching is the unsteady part accuracy / steady part It was confirmed that the accuracy was good. Since the plate thickness variation is larger at the joint than the roll eccentric amount, it can be said that it is better to control the plate thickness variation with priority over the error of the roll eccentric amount.

ここでΔｈは推定板厚と検出板厚の偏差、ΔＣは検出形状と目標形状の偏差から設定される変更すべきメカニカル板クラウン量、Ｋ_ｈＰは板厚に及ぼす荷重の影響係数、Ｋ_ｈＦは板厚に及ぼすベンディング力の影響係数、Ｋ_ＣＰはメカニカル板クラウンに及ぼす荷重の影響係数、Ｋ_ＣＦはメカニカル板クラウンに及ぼすベンディング力の影響係数、ΔＰはΔｈとΔＣを満足させるために変化させるべき荷重変化量、ΔＦはΔｈとΔＣを満足させるために変化させるべきベンディング力変化量である。
この連立方程式をΔＰとΔＦについて解くと

これは目標の板厚とメカニカル板クラウンに変化させるための荷重変化量とベンディング力変化量である。ベンディング力変化は通常油柱の圧力等で検出しているので、その値がΔＦ分変化するように油柱位置を変化させればよい。荷重変化は圧下位置の変化によって得られるが、圧下位置変化は式（６）のように当該荷重時の影響係数Ｋ_ｈＰを乗じた値となる。

この差Δｈ’は式（１）に従ってＰＩ制御を行う際にはｅ（ｔ）に対応する。ベンディング力変更についても同様に制御を行う場合にはΔＦがｅ（ｔ）に対応する。 If the rolling position is changed to perform plate thickness control, load fluctuations may occur and shape defects may be induced. In the absolute value gauge meter AGC, since the estimated thickness value is accurate, it is possible to increase the control gain at the joint, and in this case, the amount of change in the reduction position becomes large. The shape can be compensated by keeping the mechanical plate crown at the crown definition point constant, so the influence coefficient of load and bending force on the mechanical plate crown is obtained in advance, and the bending force is changed based on the influence coefficient. Can be compensated for. Since the change of the rolling position and the change of the bender affect both the thickness and shape, in order to compensate for both the thickness and shape at the same time, the influence coefficient of the load and bending force on the thickness is also obtained, What is necessary is just to obtain | require and control the change amount of a reduction position and bending force by solving simultaneous equations of Formula (2) and (3) so that a plate | board crown may become a desired value.

Where Δh is the deviation between the estimated plate thickness and the detected plate thickness, ΔC is the mechanical plate crown amount to be changed set from the deviation between the detected shape and the target shape, K _hP is the coefficient of influence of the load on the plate thickness, and K _hF is Influence factor of bending force on plate thickness, K _CP is influence factor of load on mechanical plate crown, K _CF is influence factor of bending force on mechanical plate crown, ΔP should be changed to satisfy Δh and ΔC The load change amount, ΔF, is a bending force change amount that should be changed to satisfy Δh and ΔC.
Solving these simultaneous equations for ΔP and ΔF

This is the load change amount and bending force change amount for changing to the target plate thickness and mechanical plate crown. Since the bending force change is normally detected by the oil column pressure or the like, the oil column position may be changed so that the value changes by ΔF. Although the load change is obtained by the change in the reduction position, the change in the reduction position is a value _obtained by multiplying the influence coefficient K _hP at the time of the load as shown in Expression (6).

This difference Δh ′ corresponds to e (t) when performing PI control according to the equation (1). When the bending force change is similarly controlled, ΔF corresponds to e (t).

  Measure the thickness and shape when the plate thickness / shape non-interference control using the above influence coefficient is performed with the control gain switching type of the joint portion, which is a steady portion and an unsteady portion, and when only the plate thickness control is performed. did. Table 2 shows the results. Although there is almost no difference in the on-gauge ratio between the stationary part and the unsteady part and the shape fluctuation of the stationary part, it can be seen that the shape fluctuation of the unsteady part having a large load fluctuation is halved, which is effective.

  As the number of rolled sheets increases, errors occur in the estimated thickness and the thickness detected by the thickness gauge due to the growth of the thermal crown and roll wear. Further, in the above-described constant control of the mechanical plate crown, the control end is changed so as to lock on when the desired shape is obtained and the mechanical plate crown is maintained. There is no choice but to change. Since changing the bender also affects the plate thickness, it is necessary to perform plate thickness / shape non-interference control in order to obtain a desired shape. The shape is preferably controlled based on the output of the shape detector on the rolling mill exit side. Formulas (2) and (3) are established using the influence coefficient from the deviation between the desired shape and the detected shape, and the deviation between the target plate thickness and the estimated plate thickness at the same point, and the reduction position and bender are changed. The quantity can be calculated and compensated.

  Immediately after the start of rolling, the mechanical plate crown cannot be locked on at a desired value, so this control is effective even immediately after the start of rolling. Therefore, the sheet thickness and shape stability immediately after the start of rolling were investigated. When the plate thickness is controlled only by the estimated plate thickness without performing feedback from the delivery side plate thickness gauge, the growth of the thermal crown increases as the number of rolling increases as shown in FIG. occured. Since the number of rolling is small, no wear occurs, but when the number is increased, wear is also caused and the deviation is changed. Therefore, it is necessary to take the same measures as this thermal crown. In addition, since the relationship between the number of rolling rolls and the growth amount of the thermal crown seen this time varies depending on the rolling conditions, it is meaningless to model the current relationship as it is. Since the deviation is captured by the thickness gauge, the deviation thickness and shape non-interference control may be used to compensate using the influence coefficient.

  The shapes were compared by shape control immediately after the start of rolling. As shown in FIG. 6, when non-interference control is performed based on the influence coefficient, it is possible to perform early control based on the difference from the target value, so that the shape is stabilized quickly, but the thickness / shape non-interference control is performed If not, it takes time to stabilize because there is no choice but to change gradually. The effect of plate thickness / shape non-interference control can be confirmed.

ここでｈ_ｏｌｄはこれまで使用していた推定板厚であり、検出板厚による補正を行う前もしくは前回補正を行った値、Ｓは初期の圧下位置であり上下ロールの無負荷時のギャップに相当し、ＭＳはある任意の特定荷重がかかった際のミルストレッチであり、ｈが学習によって新たに設定される推定板厚である。 Further, since the difference Δh ″ between the estimated plate thickness and the detection plate thickness is caused by a factor with a slow change with time, such as a thermal crown, it is not normally considered that Δh ″ changes rapidly. Therefore, if this Δh ″ is added to the model estimated value as shown in the equation (7), it can be controlled on the basis of that, and this is effective.

Here h _old is an estimated thickness that has been used so far, the value was before or previous correction corrects the detection plate thickness, S is the initial pressing position to the gap at the time of no load of the upper and lower rolls Correspondingly, MS is a mill stretch when an arbitrary specific load is applied, and h is an estimated plate thickness newly set by learning.

  As described above, after obtaining the deviation from the estimated plate thickness and the target plate thickness, the output is obtained according to the PI control, and the reduction position is changed by multiplying it by the control gain. If the deviation between the estimated plate thickness and the target plate thickness is large, the larger proportional control gain will change the reduction position abruptly with respect to the target value, so if you can maintain stability, multiply the larger gain There are good things mentioned above. In terms of hardware, high-performance hydraulic pressure reduction is being introduced, and the gain can be increased. On the other hand, elements for determining a control amount for finally changing the reduction position and the bender position are also in the proportional gain and the integral gain in the case of PI control. Since the proportional gain directly calculates the control amount by multiplying the deviation, if the proportional gain is large at the joint where the deviation is large, it will be output so as to greatly change the reduction position, and the thickness deviation will be removed quickly. And show its power. However, as described repeatedly until now, it is an essential condition that the estimated thickness is highly accurate. Since the integral gain outputs a value integrated with time in order to remove the deviation, the same concept as the proportional gain holds for the integral gain at the junction which is a non-stationary portion where there is a high possibility that a large deviation has occurred. That is, the same effect can be obtained even if the integral gain is increased at the junction. Needless to say, both may be increased simultaneously. However, care must be taken not to over-control the two.

  Needless to say, the present invention is not affected by the difference between hot rolling and cold rolling, the mill type, the mill configuration, and the application stand.

  In order to confirm the effect of the present invention, a rolling experiment using a 4Hi single stand cold tandem rolling mill was performed. An X-ray thickness gauge is installed on the stand exit side, and the stand is equipped with a load cell, a hydraulic reduction device, and a work roll bender. Two types of (1) BISRA AGC and (2) absolute value gauge meter AGC were used this time, and a monitor AGC from the final stand outlet side thickness gauge was added to each. The proportional gain, integral gain, and control gain shown in Table 3 were used.

  Rolling is performed by joining two pieces at each gain, and the thickness change is abrupt in the vicinity of the joint, and it is difficult to measure with an X-ray thickness gauge due to the filter. The effect of each control system was determined by measuring with a thickness gauge. Both of the coils are plain steel, and the first coil has a plate width of 1210 mm, an inlet plate thickness of 4.8 mm, and an outlet plate thickness of 3.426 mm. The second coil has a plate width of 1111 mm, an inlet plate thickness of 4.3 mm, and an outlet plate thickness of 3.088 mm. As the roll diameter of the rolling mill, backup roll diameters of 1098 and 1028 mm and work roll diameters of 418.2 and 418.5 mm were used. The bending force was constant and 100 kN / chock, and the rolling speed of the joint was 100 m / min on the outlet side. The location where the gain is changed is 6 m before and after the joint. Each control system compared off-gauges at 12 m before and after the joint. Considering the future, considering the future, the target plate thickness is set to ± 1.0%, which is more severe than the current strict material. The on-gauge rate was calculated from the length to the part.

  As a result of rolling, as shown in FIG. 7, in the absolute value gauge meter AGC, the thickness estimation is highly accurate, and it can be seen that increasing the respective gains reduces the off gauge and is effective. On the other hand, with BISRA AGC, it is difficult to estimate the plate thickness at the joint, and it can be seen that off-gauge increases conversely when the gain is increased. It was confirmed that gain increase would be effective when combined with AGC, which has good thickness accuracy.

It was verified the effect of the thickness and shape decoupling control using the influence coefficients using laboratory rolling machine shown in Example 1. The shape was confirmed by visual observation of a sample obtained by cutting out the joint. Compared with Example 1, it was confirmed that the shape was clearly improved visually.

It is a figure which shows the example of the plate | board thickness control of cold tandem rolling. It is a figure which shows the example of the plate | board thickness control using PI control. It is a figure which shows the example of the gain adjustment method of this invention. It is a figure which shows an on gauge rate at the time of changing a control gain in a junction part. It is a conceptual diagram which shows the deviation of the estimated board thickness and target board thickness which generate | occur | produce by disturbance (here thermal crown). It is a figure which shows the shape control performance by the presence or absence of the shape control using an influence coefficient. It is a figure which shows the on gauge rate at the time of changing a control gain, a proportional gain, and an integral gain.

Explanation of symbols

1a, 1b: Work rolls 2a, 2b: Intermediate rolls 3a, 3b: Backup roll 4: Rolled material 5: Sheet thickness meter 6: Mill motor 7: Load detection device 8: Hydraulic reduction device 9: Tension meter 10: Bender

Claims (3)

  In continuous rolling performed by joining the preceding material and the following material, the sheet thickness is estimated based on the mill stretch model used for the absolute value gauge meter AGC in the rolling mill having the load detecting means and the reduction position correcting means, and is unsteady. Increase the plate thickness control gain, proportional gain, integral gain in any fixed section of the unsteady part or more than the steady part so that the target value of the plate thickness and the estimated value match A plate thickness control method characterized by correcting a reduction position.   In continuous rolling performed by joining the preceding and succeeding materials, the influence coefficient of the load and the influence coefficient of the bending force on the sheet thickness in advance by a rolling mill having a load detection means, a bending force detection means, a reduction position correction means and a bender. In addition, the influence coefficient of the load and the influence coefficient of the bending force on the mechanical plate crown at any defined point are calculated, and the target value and absolute value gauge meter of the unsteady part thickness are calculated using these four influence coefficients. The steady part is one or more of control gain, proportional gain, integral gain for plate thickness control in an arbitrary constant section of the unsteady part so that the estimated value based on the mill stretch model used for AGC matches. The control position, proportional gain, integration for shape control in an arbitrary fixed section of the unsteady part Thickness and shape decoupling control method characterized by operating the vendor to any or more than one-in is increased than the steady section to compensate for the mechanical strip crown varies. It has a plate thickness detection means and a shape detection means on the stand exit side, and compares the detection plate thickness in the stationary part with the estimated plate thickness based on the mill stretch model used for the absolute value gauge meter AGC and Compare the detected shape with a predetermined target shape, and based on the difference between the plate thickness detection value and the plate thickness estimated value and the difference between the shape detection value and the shape target value, the influence coefficient of the load on the plate thickness and and correcting the estimated thickness with further correcting the pressing position and the bending force with the influence coefficient of the influence coefficient and bending force loads on the mechanical strip crown in influence coefficient as well as any defined point of bending force The thickness / shape non-interference control method according to claim 2 .

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