JPH0211205A - Method for controlling plate thickness in hot rolling mill - Google Patents

Abstract

PURPOSE:To improve the product plate thickness accuracy by installing a plate thickness sensor in the vicinity of a reversible rolling mill and performing feedback control in a pass in which a stock approaches the sensor and feedforward control in a pass in which the stock approaches the mill. CONSTITUTION:A sheet thickness sensor 6 is installed in a position being a prescribed distance (l) apart from the center of a reversible rolling mill 1 and sampling data for plate thicknesses from the sensor 6 is inputted to a digital controller 7. In that time, various parameter from a host computer 8 are inputted to the controller 7 and a feedback or a feedforward control amount is inputted to an analog AGC control panel 9 based on the above parameters and a sheet thickness detection value. In a pass in which a stock 2 to be rolled approaches the sensor 6, feedback control is performed and in an opposite pass, feedforward control is performed. Thus, the product sheet thickness accuracy is improved because influence of accuracy of a gage-meter system is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling plate thickness in a hot rolling mill, and in particular to controlling the plate thickness of a material to be rolled using a reversible rolling mill such as a thick plate mill. The present invention relates to a method for controlling plate thickness of a hot rolling mill, which is suitable for controlling the thickness of a hot rolling mill.

[Conventional technology]

Conventionally, in reversible hot rolling mills, so-called automatic plate thickness control (hereinafter referred to as AGC) is often introduced for the purpose of reducing the plate thickness distribution in the longitudinal direction of the rolled material. Generally, a lock-on type feed bank AGC is used as this AGC, and the feed bank amount is the rolling load F detected by a load meter,
The exit side plate thickness is calculated using the gauge meter equation (1) below based on the roll opening degree S detected by the rolling position detection device.

h=S+F/M ・・・・・・・・・・・・(1)
Here, M is the mill constant of the rolling mill.

This lock-on type feed bank AGC has limited responsiveness and cannot completely satisfy recent high quality demands.

Therefore, as previously disclosed in JP-A No. 56-26611, the present applicant has determined that the thickness of the bus in the bus is The longitudinal temperature distribution of the rolled material is determined, and then the longitudinal temperature distribution of the rolled material in the next bus is predicted from the longitudinal temperature distribution of the current pass and the rolling conditions of the next bus. Temperature distribution prediction: Similarly, the longitudinal rolling load distribution in the next bus is predicted from the target plate thickness of the next bus and the longitudinal outlet side plate thickness distribution of the bus, and from the longitudinal rolling load distribution of the next pass, the next Predict the longitudinal plasticity constant distribution of the rolled material in the bus,
Based on this, we have proposed a feedforward type AGC that controls the rolling reduction amount in the next pass, and this feedforward type AGC also uses the exit side Fi and thickness calculated using the gauge meter formula in (1) 2. is used for control.

[Problem to be solved by the invention]

However, the above conventional feedforward method AG
In case of C, it is clear that the accuracy of the gauge meter type (Type 11) affects the accuracy of the exit side plate thickness, and as a result, it also affects the accuracy of the 1-thickness control wholesaler. Accuracy control of the formula is an important factor in maintaining plate thickness accuracy.In addition, due to various conditions that are not reflected in the gauge meter formula, the calculated exit plate thickness using the gauge meter formula may differ from the actual exit plate thickness. There was an unresolved problem that it would go away.

In addition, the above feedforward method A is used in a reversible rolling mill.
When using GC, time is required to transport the material to be rolled between the detection operation of the plate thickness distribution of the pressurized abrasive and the actual rolling control operation. This feedforward type AGC is suitable for variations in plate thickness distribution.
In addition, in order to match the output timing of the rolling reduction control signal based on the plate thickness distribution detected in the preceding pass so that it corresponds to the actual plate thickness distribution, it is necessary to There was also an unresolved issue in that complicated processing was required because it was necessary to take into account the elongation of the material in the longitudinal direction.

Therefore, this invention was made by focusing on the unresolved problems of the above-mentioned conventional example, and aims to improve the thickness accuracy of the product and to simplify the complicated process for phase alignment mentioned above. The purpose of the present invention is to provide a method for controlling plate thickness in a hot rolling mill that enables the following.

[Means to solve the problem]

In order to achieve the above object, the method for controlling the plate thickness of a hot rolling mill according to the present invention is to control the plate thickness of a hot rolling mill by adjusting the amount of reduction of a hot rolling mill that rolls a material to be rolled. In the thickness control method, a plate thickness sensor is disposed on one outlet side of the reversible rolling mill, and the rolling amount of the hot rolling machine is determined based on the plate thickness detection value of the plate thickness sensor, so that the rolled material is Feedback control is performed on a path with a large steady-state deviation in the path from the hot rolling mill to the plate thickness sensor, and feedforward control is performed on a path with a large plate thickness deviation in the path from the plate thickness sensor to the hot rolling machine. It is characterized by minimizing plate thickness deviation and steady-state deviation.

[Effect]

In this invention, the actual plate thickness of the rolled material rolled by the hot rolling mill is detected by the plate thickness sensor, and when the rolled material is rolled toward the plate thickness sensor side and the steady deviation is large, Feedback control of the rolling reduction amount based on the detected value of the plate thickness sensor reduces the plate thickness offset i, and the plate thickness deviation is large when the material to be rolled is rolled from the plate) 7 sensor side. Sometimes, by performing feedforward control of the rolling distance based on the detected value of the plate thickness sensor, the plate thickness deviation in the longitudinal direction of the plate thickness is reduced and the plate thickness accuracy of the rolled material is improved.

Furthermore, since both controls are performed based on the plate thickness detection value of the plate thickness sensor, the plate thickness accuracy does not deteriorate due to various conditions that are not reflected in the gauge meter type.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a system diagram showing a control system when the present invention is applied to a reversible hot rolling mill.

In the figure, ■ is a reversible hot rolling mill, and is equipped with work rolls 3a and 3b facing each other with a material to be rolled 2 in between, and a pair of Panoqua knob rolls 4a and 4b in rolling contact with these. The amount of reduction of the work roll 3a is controlled by the hydraulic reduction device 5, and the material to be rolled 2 is sequentially rolled by reciprocating the material 2 a plurality of times.

In the mill housing on the left side of the hot rolling mill 1, a plate thickness sensor 6 made of, for example, a TvA thickness gauge is arranged facing the rolled material 2 at a position a predetermined distance l from the mill center line. A detected value of the plate thickness of the material to be rolled 2 is output from the plate thickness sensor 6, and this is sampled by the digital controller 7 at predetermined time intervals or every time the material to be rolled moves a predetermined distance. The number of samples for plate thickness detection values depends on the transfer speed of the rolled material, but up to 60 samples per bus.
That's about it.

This digital controller 7 includes various controls from a host computer 8 that controls the entire hot rolling line. 'llll parameters are manually input, and based on these control parameters and the plate thickness detection value, foot control and feedforward control amounts are selectively calculated, and the calculated control amounts are sent to the analog AGC control panel 9. Output to. Here, the feed hack control amount is performed by the bus in which the material to be rolled 2 goes from the hot rolling a1 to the plate thickness sensor 6, and the feed forward control is performed when the material to be rolled 2 is transferred from the plate thickness sensor 6 side to the hot rolling mill 1. Do it on the bus you're heading towards. Feedforward control is performed in the first half of the thickening bath, where it is relatively easy to eliminate variations in the thickness of the rolled material 2, and feed hacking is performed in the final 1.2 bath of thickening to obtain the target thickness of the product. The basic idea is to control.

The analog AGC control panel 9 is a digital controller 7
The hydraulic rolling down device 5 is controlled based on the control amount inputted from the machine, and the roll opening degree is changed to control the thickness of the material to be rolled.

The foot bank control by the digital controller 7 is performed based on the target plate thickness h3. ．． and the plate thickness detection value h' detected by the plate thickness sensor 6 are input to the digital controller 7. Here, the plate thickness detection value h' includes the dead time element 10 of the transfer function e - S L based on the time t required for the rolled material to move the distance β between the mill center line and the plate thickness sensor 6. A delay time between the transfer function e-5Ls and the dead time element 11 based on the response time t of the plate thickness sensor 6 is included.

The digital controller 7 controls the target plate thickness h aiffi
Calculate the deviation Δh between
The roll opening movement amount ΔS is calculated by proportional/integral compensation expressed by the following round equation based on
It is output to the hydraulic pressure lowering device 5 via the C panel 9.

Here, G is the gain calculated by the host computer 8 for each rolling bus, T is the time constant of the integral element in the digital controller 7, S is the Laplace operator, and the time constant T
is the time t (-
ff/v, v is the transfer speed of the rolled material 2) and the plate thickness sensor 6
is a function of the response time ts.

T=f (t, ts) ・・・・・・・・・・・・
The 00 hydraulic rolling down device 5 changes the roll opening degree S according to the roll opening degree movement amount ΔS, and as a result, the exit side plate thickness of the rolled material 2 as a control target is controlled. By performing this feed bank control, as shown in FIG.
AGC using the conventional gauge meter type shown in Figure (b)
Compared to the above, the thickness of the plate is smaller, and the plate can be brought closer to the target plate 17.

In addition, in the feedforward control, as shown in the block diagram of FIG. The disturbance ΔH is added to the rolling mill system 12 including the rolling device 5 as a disturbance, and this disturbance ΔH is transmitted to the rolling mill system 12 based on the time required for the rolled material to move the distance M1 between the mill center line and the plate thickness sensor 6. It is transmitted to the digital controller via the dead time element 10 of the function e-SL, while it is transmitted to the digital controller through the dead time element 11 of the transfer function e-3Ls based on the response time of the plate thickness sensor 6. .

The digital controller 7 calculates the roll opening movement amount ΔS to the hydraulic lowering device 5 according to the following Cl5I formula.

ΔS = GzΔH・・・・・・・・・・・・05)
Here, G2 is a control gain, which is calculated by the host computer 8 as described below.

In other words, the roll opening movement amount ΔS and the entrance plate thickness disturbance Δ■
The transfer function from 1 to the outlet thickness deviation Δh is G,
When and GH, the relationship Δh=Q, ・ΔS+GH・ΔH...Oe is established, and the roll opening movement amount ΔS when the exit side plate thickness deviation Δh−〇 is set at G6) 2. The relationship with the disturbance ΔH is as follows: Δ5=(Go/Gs)ΔH...0η, and the coefficient part (-cH/cs) on the right side of this equation (171) becomes the control gain G2.

The disturbance ΔH detected by the plate thickness sensor 6 actually affects the rolling mill system 12 to be controlled because of the dead time element 1.
0 is delayed by the delay time t, the roll opening movement amount ΔS calculated by the formula 09 is delayed by the time calculated by the formula 08 below by the shift memory 13, and then transferred via the analog AGC board 9. It is output to the hydraulic pressure reduction device 5.

This delay time t1 is determined by the distance l between the plate thickness sensor 6 and the mill center line, the transfer speed of the rolled material 2, and the plate thickness sensor 6.
Due to the response time t, 1m ``'' I! /V
L 5 ......08) is given.

By performing this feedforward control, as shown in Fig. 5 (al), the deviation in the in-machine plate thickness due to skin marks is reduced compared to the AGC using the conventional gauge meter type shown in Fig. 5 (b). can be done.

Furthermore, examples of combinations of feedforward control FF and feedback system 4iFB are shown in Tables 1 and 2 below. Here, Table 1 shows a control example when the rolled material 2 is passed through 5 passes, and Table 2 shows a control example when the pressed abrasive material 2 is passed through 6 passes. In addition, blank spaces in Tables 1 and 2 are as follows:
AGC control using a conventional gauge meter type (see, for example, Japanese Patent Laid-Open No. 5,626,611) is performed.

As shown in Table 1 and Table 2, according to the above embodiment, based on the plate Ig and the detected value of the plate thickness sensor 6, at least in passes where the in-machine thickness deviation of the rolled material is large, the rolled material 2 is By performing feedforward control when going from the plate thickness sensor 6 to the hot rolling mill 1, the in-machine plate thickness deviation can be reduced, and at least there is a difference between the measured plate thickness of the rolled material and the target plate thickness. In a pass with steady deviation (offset), the rolled material 2
By performing feed bank control when the steel passes from the hot rolling mill 1 to the plate thickness sensor 6, the offset amount of the plate thickness can be reduced, and the plate thickness accuracy of the product can be improved. Further, during feedforward control, phase matching can be performed simply by providing the delay time t7 using the shift memory 13, and this phase matching process can be simplified. Moreover, since feedback control and feedforward control are performed based on the plate thickness detection value directly measured by the plate thickness sensor, it is possible to reliably prevent plate thickness accuracy from deteriorating due to various conditions that are not reflected in the gauge meter method. can do.

Therefore, in the case of the reversible hot rolling mill 1 as described above, both feedback control and feedforward control can be performed, so as shown in Table 3 below, it is possible to perform both feedback control and feedforward control. Compared to AGC, it is possible to further improve the accuracy of the product thickness.

Table 3 Note that in the above embodiment, the case where the present invention is applied to the reversible hot rolling mill 1 has been explained, but the present invention is not limited to this, and the present invention is not limited to this, and the present invention is not limited to this. It can also be applied to hot rolling mills such as When placed in the position, feedback control is performed.

〔Effect of the invention〕

As explained above, according to the present invention, when the steady deviation is large during rolling of the material to be rolled from the hot rolling mill to the plate thickness sensor, feedback is provided based on the plate thickness detection value detected by the plate thickness sensor. Since the rolling reduction amount of the hot rolling mill is controlled, the amount of sheet thickness offset is reduced, and
When the rolled material is being rolled from the plate thickness sensor to the hot rolling mill and there is a large thickness deviation in the machine, feedforward control is performed based on the plate thickness detection value detected by the plate thickness sensor to control the hot rolling machine. Since the reduction amount is controlled, the thickness deviation in the longitudinal direction of the plate thickness is reduced, improving the thickness accuracy of the rolled material, and the directly measured plate thickness detection value can be used for feedback control and feedforward control. Since this is reflected, effects such as being able to reliably prevent plate thickness accuracy from deteriorating due to various conditions that are not reflected in the gauge meter system can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of feedback control applicable to this invention, and FIG. 3 is a block diagram of feedforward control applicable to this invention. Figures 4 (a) and (bl) are characteristic diagrams showing plate thickness deviations in feedback control according to the method of the present invention and AGC control according to the conventional method, respectively, and Figure 5 (al
and fbl are characteristic diagrams showing plate thickness deviations of feedforward control according to the present invention method and AGC control according to the conventional method, respectively. In the figure, l is a hot rolling machine, 2 is a rolled material, 5 is a hydraulic rolling device, 6 is a plate thickness sensor, 7 is a digital controller, 8
is a host computer, and 9 is an analog AGC control panel.

Claims (1)

[Claims] (1) In a method for controlling plate thickness of a hot rolling mill that controls plate thickness by adjusting the rolling reduction amount of a hot rolling mill that rolls a material to be rolled,
A plate thickness sensor is disposed near the reversible rolling mill, and the rolling amount of the hot rolling mill is determined based on the plate thickness detection value of the plate thickness sensor, so that the rolled material is transferred from the hot rolling machine to the plate thickness. Feedback control is performed on a path with a large steady-state deviation in the path toward the sensor, and feedforward control is performed on a path with a large in-machine thickness deviation in the path from the plate thickness sensor to the hot rolling mill, thereby controlling the in-machine plate thickness deviation and the steady-state deviation. A method for controlling plate thickness in a hot rolling mill, characterized in that the thickness is minimized.