JPS63160714A - Automatic plate thickness control method for rolling mill - Google Patents

Abstract

PURPOSE:To improve the accuracy in plate thickness by using a detection plate thick ness and detection plate length at an inlet side and outlet side, correcting a rolling reduction amt. based on the established rule of a mass flow in the case of a rolling mill being at the time of an acceleration and speed reduction and correcting the rolling reduction amount by using the detection plate thickness in the case of a constant speed time. CONSTITUTION:The plate lengths at the inlet side and outlet side of a rolling mill are detected by an inlet side plate length gage 24, outlet side plate length gage 34. The plate thickness at the inlet side of a rolling mill is detected. Then, whether the rolling speed of a rolling mill is in a constant speed state or in a speed acceleration and reduction state is detected in order to operate or judge the output of the rolling reduction with the automatic plate thickness controller of either that by the established rule of a mass flow or that by a feed forward control. At the time of a speed accelera tion or deceleration, the operation of the value to correct the rolling reduction amt. is performed to perform the automatic plate thickness control by the mass flow estab lished rule and at a constant speed time the rolling reduction correction amt. is operat ed with that by a feed forward control. This correction amt. is outputted to an electro- hydraulic servo valve 30 to perform the plate thickness control.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an automatic plate thickness control method for a rolling mill, and in particular, an automatic plate thickness i control method for a rolling mill suitable for use when performing automatic plate thickness control to improve the plate jXFs degree over the entire length of the coil.
Concerning improvements in control methods.

[Conventional technology]

In determining the quality of a rolled plate, the thickness of the plate is one of the important quality control items. Automatic plate thickness control (automatic gauge control: AGC) is a technology for increasing this plate thickness to -2, and one of them is the automatic rolling reduction rate control of a rolling mill shown in Japanese Patent Application Laid-open No. 57-181711. There is a way. In this automatic rolling reduction rate control method, the length of the outlet plate is calculated from the length of the plate entering the rolling machine, the thickness of the plate entering the rolling machine, and the target rolling rate based on the constant Jjt flow rate law (constant mass flow law) of the rolled material. The length is compared with the actually measured outlet plate length, and the rolling reduction amount of the rolling mill is controlled based on the comparison result. By the way, according to the law of constant mass flow rate, the relationship between the volume V HJ of a predetermined portion of the plate material before rolling at a certain moment and the volume VOJ when the predetermined portion is rolled and comes out on the exit side is expressed by the following equation (1). The state of change in the thickness of the predetermined portion (indicated by section j in the figure) before and after rolling is shown in Figures 4(A) to (C).
). V i J ”V Oj・
・・・・・・・・・ (1) Note that FIG.
(hereinafter referred to as section j) is located immediately before the work roll 16 of the rolling mill. Figure (B) shows the case where the section j is being rolled and the next section j+1 is located immediately before the work roll 16. The same figure (C) shows a state in which the rolling of the section j has been completed and the next section j+1 is being rolled. Here, Lij is the length of the plate on the entrance side of the rolling machine for the above classification j, Gij is the set value of the plate thickness on the inlet side, ΔG i J is the deviation of the actual value of the plate thickness from the set value GiJ, and is the length of the plate on the exit side. L
Oj, the set value of the outlet plate thickness is GOJ, the deviation of the actual value from the set value GOj of the outlet plate thickness is ΔGOJ, and if the plate corrugation in the width direction is ignored, equation (1) becomes the following equation (2). It can be converted as follows. Li, ・(GIJ+ΔG+J) = Lo j ・(Go J + ΔGo
J) ・"・=(2>Also, if it is assumed that the actual exit plate thickness becomes the set plate thickness GOj (if the exit plate thickness deviation ΔGo J = O), then j − as shown in FIG. In the first division J-1, the inlet side plate thickness G i ; -1' becomes as shown in the following equation (3) from equation (2): GiJ-*'=(LoJ-z/Lij-t)xGoJ-
t ・・・・・・(3) Therefore, the difference ΔGJ between this entrance side plate thickness GiJ-1' and the actual entrance side plate thickness GiJ' of section j is expressed by the following formula (4) % formula % And this difference ΔGJ If the hydraulic cylinder of the rolling mill is operated accordingly and the entry side plate thickness deviation ΔciJ is corrected,
The exit plate thickness deviation ΔGOJ should be zero.

[Problems to be solved by the invention]

However, when a touch roll is used to detect the length of the plate when correcting the one-hole difference in the entrance plate thickness based on the constant mass flow rate law as described above, slippage occurs between the touch roll and the plate during high-speed rolling. In some cases, the plate thickness accuracy could not be said to be good even at a constant speed. On the other hand, automatic plate thickness control has conventionally been based on feedforward control in addition to the feedback control described above. This feedback forward control will be explained with reference to FIG. 4, for example. The reduction cylinder is operated from the section j, j-1st entry side plate thickness deviation ΔciJ, ΔGiJ-1, and the value to correct the reduction amount, that is, the reduction correction amount ΔGJ ' with the following formula (
5). ΔG j ''' (G i J+ΔG+J)−(Gi
J-1+ΔGij-1> =ΔG i j−ΔGiJ-1 ・・・・・・・・・(5) Equation (5) is based on the following equation: determined to be equal. By the way, the automatic plate thickness control using the feedforward control described above detects only the entry side plate thickness Gi to determine the reduction amount, so the change in state that occurs when the plate material moves from the entry side thickness gauge to the work roll poses a problem. . This state change includes, for example, a change in the thickness of the oil film between the work roll and the plate material. In addition, the rolling speed changes due to the state change, and during rolling acceleration/deceleration when the state change occurs, for example, at the start and stop of rolling, the plate thickness accuracy is generally lower than the conventional automatic plate thickness control based on the constant mass flow rate law. will also be inferior. On the other hand, when rolling at a constant speed with little change in state, particularly during high-speed rolling, better plate thickness accuracy can be obtained than automatic plate thickness control based on the constant mass flow rate law, which causes the problem of touch roll slipping. As mentioned above, automatic plate thickness control using the constant mass flow rate law and automatic plate thickness control using feedforward control each have their advantages and disadvantages, but it is important to understand these advantages and disadvantages and take advantage of only their strengths to improve plate thickness accuracy. Automatic plate thickness i that can improve
1. Conventionally, there was no control.

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned problems of the conventional art, and takes advantage of both automatic plate thickness control based on the constant mass flow rate law and automatic plate thickness control based on feedforward control to achieve automatic plate thickness control. It is an object of the present invention to provide an automatic plate thickness control method for a rolling mill that can perform control, compensate for the drawbacks of both, and reliably improve plate thickness accuracy.

[Means to solve the problem]

In order to set the thickness of a plate material rolled by a rolling mill to a target thickness, the present invention measures the rolling reduction amount of the rolling mill by measuring the plate thickness detected at the input side of the rolling machine, the input side, and the output side of the rolling mill. When performing automatic plate thickness control with correction based on the plate length, if the rolling mill is accelerating or decelerating, the detected plate thickness and the detected plate lengths on the entry and exit sides are used to control the constant mass flow rate. The above object is achieved by correcting the reduction amount based on the detected plate thickness when the rolling mill is at a constant speed.

[Effect]

In the present invention, when performing automatic plate thickness control, when the rolling mill is accelerating or decelerating, the plate thickness detected at the input side of the rolling mill, and the plate length detected at the input side and exit side of the rolling machine are The rolling reduction amount of the rolling mill is corrected based on the constant mass flow rate law, and when the rolling mill is at a constant speed, the rolling reduction amount is corrected using the detected plate thickness. Therefore, automatic plate thickness III OII can be performed by incorporating only the advantages of both automatic plate thickness control based on the constant mass flow law and automatic plate thickness control using feedforward maj, and it is possible to reliably improve plate thickness accuracy. be able to.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. In this embodiment, the automatic plate thickness M control device as shown in Fig. 2 is controlled using the control procedure shown in Fig. 1 to optimize the plate thickness during rolling acceleration. It is something. The reversible rolling mill shown in FIG. 2 includes a payoff reel 12 for unwinding g1910, a deflector roll 14 for delivering the copper strip 10, a work roll 16 for rolling the delivered copper strip 10, and a backup roll. A roll 18, a deflector roll 20 around which the rolled copper strip 10 is wound, and a tension reel 2 for winding up the rolled steel strip 10.
2 is provided. Further, the automatic plate thickness control device for controlling the reversible rolling mill includes an entry side plate length gauge 24 for detecting the plate length of the steel strip 10 on the entry side of the rolling mill, and An entry side thickness meter 26 for detecting the thickness, a hydraulic cylinder 28 for applying a reduction blade to the backup roll 18, and a hydraulic cylinder 28 for converting an input electric signal into control hydraulic pressure and supplying it to the hydraulic cylinder 28. Electro-hydraulic servo valve 30 and steel strip 10 after rolling
an exit side thickness gauge 32 for detecting the thickness of the steel strip 10, an exit side plate length gauge 34 for detecting the length of the steel strip 10 on the exit side, the input side plate length meter 24 and the exit side plate length. Total of 34 outputs L1
, L, and the outputs of the input side thickness gauge 26 and the output side thickness gauge 32, G i J + ΔG i J, GOj + ΔGOJ, and the input side plate thickness i α difference ΔGi, The electro-hydraulic servo valve 3 is operated based on the outputs of the plate thickness deviation output circuit 38, the counter 36, and the plate thickness deviation output circuit 38 for calculating the actual outlet side plate thickness deviation ΔCO.
A control device 42 is provided for automatically controlling the plate thickness by controlling the thickness of the plate. The effects of the embodiment will be explained below. In this embodiment, the plate thickness accuracy of the steel strip 10 is improved by automatically controlling the plate thickness according to the control procedure shown in the flowchart of FIG. That is, in the control procedure shown in the figure, first, in step 110, the plate lengths Li and L on the rolling mill entry side and exit side are determined. is detected by the inlet side plate length meter 24 and the outlet side plate length meter. Next, in step 120, the plate thickness Gi at the entrance of the rolling machine is detected.In step 130, rolling is performed by either automatic plate thickness control based on the constant mass flow wall law or automatic plate thickness control based on feedforward control. In order to determine whether to calculate the output, it is detected whether the rolling speed of the rolling mill is in a constant speed state or in an acceleration/deceleration state.Next, in step 140, whether the rolling speed is in an acceleration/deceleration state is detected. It is determined whether or not the speed is being increased or decreased, and if the speed is increasing or decreasing, the process proceeds to step 150, and if the speed is not being accelerated or decelerated but is in a constant state, the process proceeds to step 160. In step 150, in order to perform automatic plate thickness control (AGC) based on a constant mass flow rate (mass flow),
Using equations 1) to (4), a value to be corrected for the reduction amount of the rolling mill to obtain the target plate thickness, that is, a reduction correction amount ΔGJ is calculated.Meanwhile, in step 160, the automatic plate thickness is calculated by feedforward control. The reduction correction amount ΔGj' is calculated using control or equation (5) above. After the arithmetic processing in steps 150 and 160 is completed, in step 170, the calculated reduction correction amounts ΔGj, ΔGj' are output to the electro-hydraulic servo valve 30 to control the plate thickness.Next, in step 180, a check is made to determine whether rolling has ended. If it is determined that rolling has not yet been completed, the process returns to step 110 and this rrA control procedure is repeated.On the other hand, if it is determined that rolling has been completed, this control procedure is terminated. In addition, the frequency of outputting the reduction correction amount ΔGJ or ΔGJ' in step 170 is that it is output every time the entrance plate length moves a predetermined length, and the automatic plate thickness is determined by the constant JM flow rate law or feedforward control. In either case of control, the same length is output. In addition, since the correction amount is calculated in either step 150 or 160, the number of calculations required for automatic plate thickness control does not overlap.Furthermore, the control timing of each plate Jzov control for the rolling speed according to the above control procedure is The relationship is as shown in FIG. Automatic plate thickness control is shown in the same figure (B). Further, in the figure, time t1 to t2 indicates acceleration, t2 to t3 indicates constant speed, and t3 to t4 indicates deceleration. The results of automatically controlling the plate thickness of stainless steel as a plate material according to the above embodiment are shown below. In this case, the material of the stainless steel is 5US430
, the plate width was 1000n, and the plate thickness was 1.011. The ratio of the length of the plate whose thickness deviation falls within the target deviation to the total length of the plate, that is, the on-gauge rate, was 96.5% in the conventional method shown in (A) in Figure 3, but in the case of (B) in the same figure, the on-gauge rate was 96.5%. ), it was confirmed that the method of the present invention improved to 97.0%. In the above embodiments, stainless steel is used as an example of the plate material, but the plate material is not certified as such, and the method of the present invention is carried out when rolling plate materials of other materials or dimensions with a rolling mill. Is possible. In addition, in the above embodiments, the present invention was applied to the automatic plate thickness i! of a reversible rolling mill. Although the present invention is adopted in a II control device, the scope of the present invention is not limited thereto, and it is clear that it can be similarly applied to, for example, an automatic plate thickness control device of a continuous rolling mill.

【Effect of the invention】

As explained above, according to the present invention, it is possible to perform automatic plate thickness control by taking advantage of only the advantages of automatic plate thickness control based on the constant mass flow rate law and automatic plate thickness control using feedforward control. An excellent effect can be obtained in that the drawbacks of both can be compensated for and the plate thickness accuracy can be reliably improved.

[Brief explanation of the drawing]

Figure 1 shows the rv of an automatic plate thickness control device which is an embodiment of the present invention.
FIG. 2 is a cross-sectional view, including a partial block diagram, showing the overall configuration of the automatic plate thickness 1c11 control device of the above embodiment; FIG. 3 is for explaining the operation of the above embodiment. A diagram showing an example of the relationship between automatic plate thickness control by the conventional method and the method of the present invention with respect to rolling speed, and Figures 4 (A) to (C) are examples of the state of the plate before and after rolling based on the constant mass flow rate law. FIG. DESCRIPTION OF SYMBOLS 10... Copper strip, 16... Work roll, 18... Backup roll, 24... Entrance plate length gauge, 26... Entrance thickness gauge, 28... Hydraulic cylinder, 30... - Electro-hydraulic servo valve, 32... Outlet side thickness gauge, 34... Outlet side plate length gauge, 36... Counter, 38... Plate thickness deviation output circuit, 42... Control device.

Claims (1)

[Claims] (1) In order to set the thickness of the plate material rolled by the rolling mill to the target thickness, the reduction amount of the rolling mill is determined by the plate thickness detected at the input side of the rolling machine, the plate thickness detected at the input side, and the plate thickness detected at the output side of the rolling machine. When performing automatic plate thickness control with correction based on the length, if the rolling mill is accelerating or decelerating, the detected plate thickness and the detected plate lengths on the entry side and exit side are used, and the control is performed based on the constant mass flow rate law. An automatic plate thickness control method for a rolling mill, comprising: correcting a reduction amount; and, when the rolling mill is at a constant speed, correcting the reduction amount using the detected plate thickness.