JP6781411B2 - Metal plate thickness control method and equipment, and metal plate manufacturing method and equipment - Google Patents

Description

The present invention relates to a method and apparatus for controlling the thickness of a metal plate using automatic plate thickness control (AGC: Automatic Gauge Control), and a method and equipment for manufacturing the metal plate.

One of the AGCs is the monitoring AGC. When a metal plate is rolled by a rolling mill, Monitoring AGC actually measures the outside plate thickness of the metal plate rolled by the rolling machine with a plate thickness gauge, and the deviation between the measured output side plate thickness and the target plate thickness becomes zero. This is a control method that controls the roll gap of the rolling mill by feedback control.

When the control gain of the monitoring AGC is small, it takes a long time for the actual plate thickness to converge to the target plate thickness, and when the control gain is large, hunting occurs and the plate thickness accuracy deteriorates. Further, in the conventional method, an appropriate control amount is calculated by the difference between the plate thickness at the rolling point and the plate thickness measured by the plate thickness gauge, which is caused by the transport time from the rolling point to the plate thickness gauge (wasting time of the control system). However, the plate thickness accuracy may deteriorate.

In order to improve the control gain of the monitoring AGC and accelerate the control start timing, there is an attempt to compensate for the wasted time by adding a Smith compensator. FIG. 4A shows the configuration of a normal feedback control system, and FIG. 4B shows the configuration of the feedback control system of the Smith compensation method. By adding a Smith compensator, it becomes possible to put the waste time e- ^{Lp · s out} of the control loop and control it as a first-order lag system.

For example, in Patent Document 1, the target plate thickness is set to the plate thickness estimated by the gauge meter method from the time when the tip of the metal plate reaches the rolling mill until it reaches the plate thickness gauge installed on the rear surface side of the rolling mill. After the rolling position was controlled and the tip of the metal plate reached the plate thickness gauge, it was estimated by a gauge meter method corrected by the difference between the plate thickness detected by the plate thickness gauge and the target plate thickness at the time of rolling at the detection point. The rolling position is controlled so that the plate thickness reaches the target plate thickness, and after the rolling point when the tip of the metal plate reaches the plate thickness gauge reaches the plate thickness gauge, the plate thickness detected by the plate thickness gauge is measured. The plate thickness control method used is disclosed.

However, when a Smith compensator was added to the monitoring AGC and a rolling test was performed with an actual machine, the amount of operation of the rolling machine by the monitoring AGC became unstable as shown in Fig. 5, and the target thickness deviation was accompanied by this. Was found to increase. The vertical axis in FIG. 5A is the operation amount of the monitoring AGC, and the horizontal axis is the position in the longitudinal direction of the plate. Further, the vertical axis in FIG. 5B is the deviation of the thickness of the protruding side plate from the target thickness, the horizontal axis is the position in the longitudinal direction of the plate, and the left side in the figure is the biting end.

Japanese Unexamined Patent Publication No. 61-86019

An object of the present invention is to shorten the time until the monitoring AGC stabilizes and to stably improve the plate thickness accuracy even in a control system in which the transfer time (waste time) between the plate thickness gauge and the rolling mill is long. ..

In order to solve the above problems, the present inventors have conducted diligent research on the cause of instability of the monitoring AGC when the Smith compensator is introduced into an actual machine. The Smith compensation method presupposes accurate identification of the dead time of the controlled object, but in actual operation, unlike the simulation, the error of the plate thickness gauge, the tracking error due to the fluctuation of the advanced rate, and the gauge meter plate thickness Control becomes unstable due to disturbances such as an error from the actual plate thickness. In the present invention, very good control was obtained by introducing the exponential smoothing process in addition to applying the Smith compensation method to the monitoring AGC.

Specifically, in the first aspect of the present invention, the plate thickness at the rolling point when rolling down a metal plate with a rolling mill is calculated from the gauge meter type as the gauge meter plate thickness, and the gauge meter plate thickness is calculated as described above. Tracking to the measurement point of the plate thickness gauge installed on the rear surface of the rolling mill, the deviation between the plate thickness measured by the plate thickness gauge and the tracked gauge meter plate thickness at the measurement point, and the rolling point. A metal plate thickness control method that dynamically controls the rolling position in the rolling mill so that the difference between the gauge meter plate thickness and the deviation between the target plate thickness is used as the monitoring operation amount. , The difference between the deviation between the plate thickness measured by the plate thickness gauge at the measurement point and the tracked gauge meter plate thickness, and the deviation between the gauge meter plate thickness and the target plate thickness at the rolling point. This is a sheet thickness control method for a metal plate that dynamically controls a rolling position in the rolling mill so that the target plate thickness is obtained by using an exponentially smoothed monitoring operation amount as the corrected monitoring operation amount.

The second aspect of the present invention is the plate thickness control method for a metal plate in which the calculation cycle of the gauge meter plate thickness and the measurement cycle of the plate thickness meter are set to be the same in the first aspect of the present invention.

A third aspect of the present invention is a method for producing a metal plate, which comprises rolling a metal plate using the method for controlling the thickness of the metal plate according to the first or second aspect of the present invention.

In the fourth aspect of the present invention, the plate thickness at the rolling point when rolling down a metal plate with a rolling mill is calculated as the gauge meter plate thickness from the gauge meter type, and the gauge meter plate thickness is applied to the rear surface of the rolling mill. Tracking to the measurement point of the installed plate thickness gauge, the deviation between the plate thickness measured by the plate thickness gauge at the measurement point and the tracked gauge meter plate thickness, and the gauge meter plate thickness at the rolling point. A metal plate thickness control device that dynamically controls the rolling position in the rolling mill so that the target plate thickness is obtained by using the difference between the deviation between the target plate thickness and the target plate thickness as the monitoring operation amount, at the measurement point. The monitoring operation amount, which is the difference between the deviation between the plate thickness measured by the plate thickness meter and the tracked gauge meter plate thickness, and the deviation between the gauge meter plate thickness and the target plate thickness at the rolling point. It is a plate thickness control device for a metal plate provided with an exponential smoothing circuit for correction by exponential smoothing.

A fifth aspect of the present invention is the plate thickness control device for a metal plate in which the calculation cycle of the gauge meter plate thickness and the measurement cycle of the plate thickness meter are set to be the same in the fourth aspect of the present invention.

A sixth aspect of the present invention is a metal plate manufacturing facility including a rolling mill for rolling a metal plate and a sheet thickness control device for the metal plate according to the fourth or fifth aspect of the present invention.

According to the present invention, since the exponential smoothing circuit suppresses a sudden change in the monitoring operation amount, the actual plate thickness can be increased regardless of the distance between the reduction point and the plate thickness gauge and the gain of the operation amount of the monitoring AGC. It converges smoothly and quickly to the target plate thickness. It is also possible to adjust the responsiveness of the monitoring AGC by adjusting the exponential smoothing constant (gain).

It is a schematic block diagram of the main part of the metal plate manufacturing equipment to which the plate thickness control method and apparatus of one Embodiment of this invention are applied. It is a block diagram of the plate thickness control device of the embodiment of this invention. (A) is a graph showing the displacement of the operation amount of the monitoring AGC corrected by the exponential smoothing circuit when the automatic plate thickness control according to the embodiment of the present invention is performed, and (b) is the aim at that time. It is a graph which shows the plate thickness deviation with respect to the thickness. (A) is a block diagram showing the configuration of a normal feedback control system, and (b) is a block diagram showing the configuration of a feedback control system introduced by the Smith Act. It is a graph which shows the displacement in the plate thickness direction of the operation amount of the monitoring AGC when the conventional automatic plate thickness control is performed, and (b) is the graph which shows the plate thickness deviation with respect to the target thickness at that time.

Hereinafter, an embodiment of a method and apparatus for controlling the thickness of a metal plate of the present invention using monitoring AGC and a method and equipment for manufacturing a metal plate will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a main part of a metal plate manufacturing facility to which the plate thickness control method and apparatus of the present embodiment are applied. This manufacturing facility includes a rolling mill 1 for rolling a metal plate such as a steel plate. The rolling mill 1 includes upper and lower work rolls 1a and 1b and upper and lower backup rolls 1c and 1d. In the example of the manufacturing equipment of the present embodiment, a metal plate such as a steel plate is conveyed from the left side of the drawing, and is rolled by the rolling mill 1 from the left side to the right side of the drawing so as to have a target plate thickness. The metal plate rolled to a predetermined plate thickness is conveyed to a post-process (not shown) provided on the right side of the drawing. The rolling mill may be either a reversible type or a non-reversible type. In FIG. 1, h _{GM (TRK)} indicates the tracked gauge meter plate thickness described later, and Δh _GM is the deviation between the measurement plate thickness h _γ and the tracked gauge meter plate thickness h _{GM (TRK)} and the reduction point. The difference between the gauge meter plate thickness h _{GM (compression point)} and the deviation between the target plate thickness h ₀ is shown, and ΔS indicates the difference between the reference gap and the actual gap.

The plate thickness control device for the metal plate in the present embodiment is arranged on the rear surface side of the rolling mill 1, and has a plate thickness gauge 2 such as a γ-ray plate thickness gauge for measuring the output side plate thickness of the metal plate, and upper and lower work rolls 1a. The opening degree between 1b and 1b, that is, the opening degree changing mechanism 3 including a hydraulic cylinder, the load meter (load cell) 4 for measuring the rolling load P at the time of reduction, and the reduction position by the work rolls 1a and 1b. A gauge meter plate thickness h _GM estimated based on the rolling load P and the roll opening measured by the rolling mill 1 is provided with a reduction position detector 5 for detecting the rolling load, a monitoring controller 6, and a plate thickness controller 7. There is a combination of a gauge meter AGC that controls the plate thickness using the gauge meter AGC and a monitoring AGC that controls the plate thickness using the plate thickness h _γ measured by the plate thickness meter 2.

FIG. 2 shows a block diagram of the plate thickness control system. In the figure, "h" is the output side plate thickness (actual plate thickness), "S" is the roll opening (final gap between the work rolls 1a and 1b), and "P" is the rolling load (actual load). "K" is the mill constant, "Km" is the predicted mill constant, "M" is the plastic constant, "Kg" is the control gain, "α" is the tuning rate, "h _γ " is the measuring plate thickness (actual thickness), and ""PI" is the PI control controller, " _Sagc-mon " is the indication gap after monitoring AGC, " _Sagc-ag " is the operation amount of the gauge meter AGC, and "0" attached to a letter or symbol in the figure. Represents the target value, and "Δ" represents the deviation. Further, reference numeral 9 in the drawing is a rolling load calculation unit that calculates the rolling load P back from the roll opening degree S, reference numeral 10 is a gauge meter AGC operation amount calculation unit, and reference numeral 11 is a gauge meter thickness calculation unit. , Reference numeral 12 is an addition unit that generates a difference between the measurement plate thickness h _γ and the tracked gauge meter thickness h _{GM (TRK),} and reference numeral 13 is a measurement plate thickness h _γ and the tracked gauge meter thickness h _{GM (reference} numeral 12 _). It is an addition part that generates a deviation between the difference from _TRK) and the difference between the gauge meter thickness h _{GM (reduction point)} and the target plate thickness h ₀ at the _{reduction point} , and reference numeral 14 is a monitoring operation amount and roll opening. It is an addition part that generates a difference from the target S _{0 of the} degree.

First, the gauge meter AGC will be described. When a load fluctuation (difference load indicated by ΔP in the figure) occurs due to a plastic fluctuation or a fluctuation of the inlet plate thickness, the fluctuation of the outlet side plate thickness is shown in the following equation (1) using the mill constant K according to the concept of the gauge meter formula. Will be done.
Δh = ΔP / K (1)
The idea of the gauge meter AGC is to compensate for this output side plate thickness fluctuation Δh by opening operation, and the compensation amount _Sagc-ag is as follows using the load fluctuation ΔP, the tuning rate α, and the expected mill constant Km. It becomes the formula (2). The tuning rate α has a value in the range of 0 ≦ α ≦ 1, and is a so-called control gain.
_Sagc-ag = α ・ ΔP / Km ・ ・ ・ ・ ・ (2)
That is, in the gauge meter AGC, fluctuations in plate thickness are eliminated by compensating for the increase in load so that the work rolls 1a and 1b are closed.

On the other hand, the monitoring AGC uses the difference between the plate thickness h _γ measured by the plate thickness meter 2 and the target plate thickness h ₀ as the manipulated variable, and compensates the plate thickness by proportional integration control. With the gauge meter AGC, it is difficult to accurately control the plate thickness to the target thickness due to the error of the gauge meter type, but with the monitoring AGC, the measured plate thickness is fed back, which can greatly contribute to the removal of the target thickness deviation. it can. However, the problem with the monitoring AGC is that waste time occurs in the control system due to the delay in transport time caused by the deviation between the rolling point of the rolling mill 1 and the measurement point of the plate thickness gauge 2. Therefore, in the present embodiment, a Smith compensator is added to compensate for the wasted time. The Smith compensator predicts and controls process activity by using a dynamic characteristic model, but in this embodiment, a gauge meter type is used as this dynamic characteristic model. The gauge meter plate thickness h _GM is expressed by the following equation (3) using the mill constant K.
Note that β is a gauge meter thickness correction term.
h _GM = P / K + S ₀ + β ... (3)

Further, "e- ^Ls " in the block diagram of FIG. 2 is the wasted time caused by the delay in the transport time from the rolling mill 1 to the plate thickness gauge 2, and the gauge meter plate thickness h _GM at the rolling point is actually used. It is a tracking unit that tracks up to the position of the plate thickness meter 2. Therefore, when the Smith compensator is introduced, tracking error, gauge meter error, etc. due to fluctuations in the advanced rate may occur, and the operation amount of the monitoring AGC may become unstable. Therefore, in the plate thickness control device of the present embodiment, the difference between the gauge meter plate thickness h _{GM (TRK)} tracked from the reduction point and the measurement plate thickness h _γ measured by the plate thickness meter 2 and the gauge meter at the reduction point When the difference between the plate thickness h _{GM (compression point)} and the target plate thickness h ₀ is set as the monitoring operation amount to be compensated, the monitoring operation amount is corrected by exponential smoothing, and the value is corrected by the plate thickness controller 7. The exponential smoothing circuit 8 is provided as a monitoring operation amount after correction. The exponential smoothing circuit 8 may be arranged after the addition unit 13 in FIG. The processing by the exponential smoothing circuit 8 is represented by the following equation (4).
Output _i = a x Input _i + (1-a) x Output _i-1 ... (4)
The input _i is the monitoring operation amount before correction input to the exponential smoothing circuit, the output _i is the monitor rig operation amount corrected by exponential smoothing output from the exponential smoothing circuit, and the output _i-1 is the previous time. The output value. Further, a is a smoothing constant and has a value in the range of 0 <a <1. If the smoothing constant a is large, the weighting on the input value is large, so that the degree of smoothing is low. If the smoothing constant a is small, the weighting on the previous output value is large, so that the degree of smoothing is large. Since the tracking error, gauge meter error, etc. are different for each rolling mill, the optimum smoothing constant a is different for each rolling mill, but according to the research by the inventors, a can be set in the range of 0.02 to 0.10. It was found that the monitoring operation amount of the monitoring AGC can be substantially stabilized.

Further, if the calculation cycle of the gauge meter plate thickness h _{GM (compression point) at} the _{reduction point} and the sampling cycle of the plate thickness meter 2 do not match, it may cause deterioration of the control amount, and therefore, as in the present embodiment. It is preferable to provide a sampling cycle adjusting unit 15 for adjusting the sampling cycle of the plate thickness gauge. The sampling cycle adjusting unit 15 has a function of making the sampling cycle of the plate thickness h _γ by the plate thickness gauge 2 the same as the calculation cycle of the gauge meter plate thickness h _{GM (compression point) at} the _{reduction point} .

As described above, by correcting the monitoring operation amount in the monitoring AGC by exponential smoothing, the monitoring operation amount in the monitoring AGC can be stabilized and the in-plate fluctuation can be suppressed. Further, by making the calculation cycle of the gauge meter plate thickness at the reduction point and the sampling cycle of the plate thickness meter the same, it is possible to further suppress the fluctuation in the plate.

As an example, using the rolling mill and the plate thickness control device shown in FIGS. 1 and 2, a steel plate having a thickness of 10 mm as a metal plate was rolled to a target plate thickness of 8 mm. A gamma-ray plate thickness gauge was used as the plate thickness gauge. In this embodiment, the sampling period of the plate thickness gauge is set to 100 mm intervals, and the rolling load P at the rolling point and the gauge meter plate thickness h _GM at the rolling point are tracked at 100 mm intervals, and the tracking points reach the plate thickness gauge. The difference between the measured plate thickness h _γ of the plate thickness gauge and the tracked gauge meter plate thickness h _{GM (TRK)} was obtained, and this difference, the gauge meter plate thickness h _{GM (rolling point) at the rolling point,} and the target When the rolling position in the rolling mill is dynamically controlled so that the deviation from the difference between the plate thickness h ₀ is used as the monitoring operation amount to reach the target plate thickness, this monitoring operation amount is exponentially smoothed by an exponential smoothing circuit and corrected. Then, the corrected value was added to the plate thickness controller as a monitoring operation amount. The smoothing constant of the exponential smoothing circuit was 0.04. The main conditions in the plate thickness control device were a mill constant of 900 ton / mm, a predicted mill constant of 950 ton / mm, and a plastic constant of 1500 ton / mm.

The monitoring operation amount corrected by the exponential smoothing circuit (referred to as "monitor operation amount" or "monitoring AGC operation amount" in the figure) of the monitoring AGC when the automatic plate thickness control according to this embodiment is performed is shown in FIG. In (a), the plate thickness deviation with respect to the target thickness (described as “γ-thickness deviation” or “target thickness deviation” in the figure) is shown in FIG. 3 (b), respectively. As described above, it was confirmed that by applying the present invention, the monitoring operation amount of the monitoring AGC was stabilized, and the plate thickness deviation with respect to the target thickness converged at an early stage.

According to the present invention, it is possible to shorten the time until the monitoring AGC stabilizes and stably improve the plate thickness accuracy even in a control system in which the transfer time (waste time) between the plate thickness gauge and the rolling mill is long. It was.

1 Rolling machine 1a, 1b Work roll 1c, 1d Backup roll 2 Plate thickness meter 3 Opening change mechanism 4 Load meter 5 Reduction position detector 6 Monitoring controller 7 Plate thickness controller 8 Exponential smoothing circuit 9 Rolling load calculation unit 10 gauge Meter AGC operation amount calculation unit 11 Gauge meter thickness calculation unit 12, 13, 14 Addition unit 15 Sampling cycle adjustment unit

Claims (6)

The plate thickness at the rolling point when rolling down a metal plate with a rolling mill is calculated as the gauge meter plate thickness from the gauge meter type, and the gauge meter plate thickness is measured at the measuring point of the plate thickness gauge installed on the rear surface of the rolling mill. Tracking up to, the deviation between the plate thickness measured by the plate thickness gauge at the measurement point and the tracked gauge meter plate thickness, and the deviation between the gauge meter plate thickness and the target plate thickness at the rolling point. It is a method of controlling the thickness of a metal plate that dynamically controls the rolling position in the rolling mill so that the difference is used as the monitoring operation amount to reach the target thickness.
The difference between the deviation between the plate thickness measured by the plate thickness gauge at the measurement point and the tracked gauge meter plate thickness, and the deviation between the gauge meter plate thickness and the target plate thickness at the rolling point. A method for controlling the thickness of a metal plate, which comprises dynamically controlling a rolling position in the rolling mill so that the target plate thickness is obtained by using an exponentially smoothed monitoring operation amount as the corrected monitoring operation amount. The method for controlling the thickness of a metal plate according to claim 1, wherein the calculation cycle of the gauge meter plate thickness and the measurement cycle of the plate thickness gauge are set to be the same. A method for manufacturing a metal plate, which comprises rolling the metal plate by using the method for controlling the thickness of the metal plate according to claim 1 or 2. The plate thickness at the rolling point when rolling down a metal plate with a rolling mill is calculated as the gauge meter plate thickness from the gauge meter type, and the gauge meter plate thickness is measured at the measuring point of the plate thickness gauge installed on the rear surface of the rolling mill. The deviation between the plate thickness measured by the plate thickness gauge at the measurement point and the tracked gauge meter plate thickness, and the deviation between the gauge meter plate thickness and the target plate thickness at the rolling point. A metal plate thickness control device that dynamically controls the rolling position in the rolling mill so that the target plate thickness is obtained by using the difference as the monitoring operation amount.
The difference between the deviation between the plate thickness measured by the plate thickness gauge at the measurement point and the tracked gauge meter plate thickness, and the deviation between the gauge meter plate thickness and the target plate thickness at the reduction point. A plate thickness control device for a metal plate, which comprises an exponential smoothing circuit that corrects a monitoring operation amount by exponential smoothing. The plate thickness control device for a metal plate according to claim 4, wherein the calculation cycle of the gauge meter plate thickness and the measurement cycle of the plate thickness gauge are set to be the same. A metal plate manufacturing facility including a rolling mill for rolling a metal plate and a sheet thickness control device for the metal plate according to claim 4 or 5.

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