JPH0910809A - Method for controlling continuous hot rolling mill - Google Patents

Abstract

PURPOSE: To obtain a control method by which follow-up performance to the reference values of thickness, interstand tension and looper angle is improved while suppressing the mutual interference among the thickness, interstand tension and looper angle in a continuous hot rolling mill and the design and adjustment of the control system are facilitated. CONSTITUTION: By dealing with the effect by the speed and thickness of the sheet on the outlet side of a stand 2 on the inlet side using a controller 10 designed based on the multivariable control theory such as the 2 degrees of freedom type optimum servo theory, the order of the equation of state is reduced (Only deviation of thickness on the outlet side, deviation of looper angle, deviation of angular speed of looper, deviation of interstand tension, deviation of speed difference of interstand speed of the sheet and deviation of looper torque are state variables.) and the screw-down location and looper torque of the stand 3 on the outlet side and mill speed of the stand on the inlet side or the outlet side are simultaneously operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the plate thickness, stand tension and looper angle of a hot continuous rolling mill,
In particular, the present invention relates to a hot continuous rolling mill control method for controlling a looper angle, a stand tension, and a stand exit side plate thickness to desired target values by using a rolling position control device, a mill speed control device, and a looper torque control device.

[0002]

2. Description of the Related Art In a hot continuous rolling mill, it is already known that plate thickness and inter-stand tension, and inter-stand tension and looper angle form a mutual interference system. There is a problem that the dimensional accuracy deteriorates. As a conventional method for solving the problem due to the mutual interference, Japanese Patent Laid-Open No. 49-28557 discloses that all stands are treated as one rolling phenomenon, and the control system of the continuous rolling mill is used as a solution of the optimal regulator problem. A method of configuring is disclosed. Further, in Japanese Patent Laid-Open No. 63-188416, a control system for rolling phenomenon is constructed as a solution of an optimal regulator problem on the basis of two stands, and when the number of stands is extended to three or more stands, the order of state equation should be increased. Discloses the method of application. Further, JP-A-2-211906 discloses a rolling phenomenon model in which a plate thickness control system, a stand tension control system and a looper angle control system independently arranged for each stand and looper are represented by a linear equation of state. And the linear state equations of the control system are made simultaneous to form a solution of the optimal regulator problem as one multivariable control system.

[0003]

However, in the above-mentioned Japanese Patent Laid-Open No. 49-28557, since all stands are treated as one rolling phenomenon, the order of the equation of state becomes very large, and the optimum regulator problem occurs. However, there is a problem that adjustment of weight matrices generally called Q and R matrices becomes very difficult.
Further, in the above-mentioned Japanese Patent Laid-Open No. 63-188416, when an optimum regulator is composed of a plurality of stands,
There is the same problem as 49-28557. Further, in the above-mentioned Japanese Patent Laid-Open No. 2-211906, feedback is provided by an optimum regulator for the plate thickness control system, the inter-stand tension control system and the looper angle control system that are independently arranged for each stand and looper. Therefore, in addition to the problem that the ability of each actuator cannot be fully utilized, there is the problem of the order as in the above-mentioned JP-A-49-28557 and JP-A-63-188416.

By the way, as described in Reference 1 (Fujisaki, Ikeda, "Construction of Optimal Servo Type with Two-Degree-of-Freedom Integration", Proceedings of the Society of Instrument and Control Engineers, Vol. 27, No. 8, pp.907-914). From the standpoint of a two-degree-of-freedom control system, the tracking characteristics for the reference input and the control characteristics for the modeling error of the controlled object and the constant value disturbance should be designed independently. In any of the above-mentioned JP-A-49-28557, JP-A-63-188416, and JP-A-2-211906, the configuration is such that it cannot be called the optimum servo system for the tracking error, and it is based on the reference value. The tracking characteristic is not considered. Therefore, there is a problem that the response of the output value when the reference value (for example, the target plate thickness) is changed during rolling is not always desirable.

The present invention has been made to solve the above problems, and suppresses the mutual interference of the plate thickness, the tension between the stands, and the looper angle, while suppressing the plate thickness, the tension between the stands, and the looper angle. It is an object of the present invention to provide a control method for a hot continuous rolling mill, which controls the temperature using a control device that can follow the reference value with good responsiveness and that can easily design and adjust the control system.

[0006]

A method of controlling a hot continuous rolling mill according to the present invention includes a torque control device for a looper arranged between stands of a hot continuous rolling mill, and a mill arranged at each stand. In a method for controlling a delivery side plate thickness, a looper angle and a tension between stands to desired values by using a speed control device and a rolling position control device, a delivery side plate thickness deviation, a looper angle deviation, a looper angular velocity deviation, a stand tension deviation, and a stand tension deviation, Set the state equation with the inter-plate speed difference deviation and looper torque deviation as state variables, and the output stand pressure reduction position deviation instruction value, looper torque deviation instruction value, and mill speed deviation instruction value of the input stand or the output stand as operation variables. At the same time, the thickness deviation of the incoming side stand and the perturbation of the outgoing side plate speed due to the change in the advance rate of the incoming side stand out of the incoming side stand speed are referred to as disturbances. , The output side plate thickness deviation, looper angle deviation and inter-stand tension deviation are set as output variables, and the output side plate thickness deviation target value, looper angle deviation target value and inter-stand tension deviation target value are used as reference value variables. ,
With the control device obtained by the multivariable control theory that can independently design the control characteristic for constant value disturbance and modeling error and the tracking characteristic for the reference input, the output stand pressure reduction position, looper torque and the input side stand or the output side stand mill. It is characterized by operating the speeds at the same time. That is, the present invention uses a looper torque control device, a mill speed control device and a rolling position control device of a hot continuous rolling mill to perform control so that the looper angle, delivery side plate thickness and inter-stand tension follow a reference value. At this time, in a rolling model of one stand with one looper, a state equation using the output side plate thickness deviation, looper angle deviation, looper angular velocity deviation, interstand tension deviation, interstand plate speed difference deviation, and looper torque deviation of the stand as state variables is calculated. Set. At this time, the deviation of the input side plate thickness of the stand and the fluctuation (perturbation) of the output side plate speed of the input side stand due to the change in the advanced rate are treated as disturbances, and excluded from the state equation to reduce the order of the state variable, In addition, since the state variables do not interfere with the adjacent one stand with one looper, when applied to a plurality of one stand with one looper, the control device is independently mounted for each one stand with one looper. By doing so, it is not necessary to expand the order of the state variable. The output stand output side plate thickness deviation, looper angle deviation, and inter-stand tension deviation are used as output variables, and the output stand pressure reduction position deviation instruction value, looper torque deviation instruction value, and mill speed deviation instruction value for the input side stand or the output side stand. Is used as a control variable, and the output side thickness deviation target value of the output side stand, the looper angle deviation target value, and the inter-stand tension deviation target value are used as reference value variables, and control characteristics for modeling error and constant value disturbance and tracking for reference input The control device is designed by the multivariable control theory (for example, the two-degree-of-freedom optimal servo theory of Document 1) that has a clear design guideline for the characteristics. The controller achieves the above-mentioned object by simultaneously operating the outlet stand pressure reduction position, the looper torque, and the mill speed of the inlet stand or the outlet stand. Since the above-mentioned state equation is set with the stand-to-stand plate speed difference deviation as one state variable,
It is sufficient to operate either the mill speed of the entrance stand or the mill speed of the exit stand.

[0007]

FIG. 1 shows a looper 1 and a rolling mill stand 2 (i-th stand) and 3 (i-th i) in a general hot continuous rolling mill.
FIG. 4 is a diagram illustrating the arrangement of (+1 stand) and is an operation explanatory diagram of the present invention. In the figure, 4 is a material to be rolled. Further, the rolling mill stands 2 and 3 are provided with reduction position control devices 5 and 6 and speed control devices 7 and 8, and the looper 1 is provided with a looper torque control device 9. Reference numeral 10 is a control device designed by the above-mentioned multivariable control theory.

Here, the i + 1 stand rolling position is S _{i + 1} , the looper angle is θ _i , and the looper angular velocity is dθ _i / d.
t, tension between stands σ _i , looper torque T _Mi , speed of rolled material on the stand side of i stand v _i , speed of rolled material on stand side of i + 1 stand Vi _{+ 1} , plate on stand side of i + 1 stand Thickness is h _{i + 1} , rolling load of i + 1 stand is P _{i + 1} , i +
S _{refi + 1} the rolling position command 1 stand, T _Mrefi the Rupatoruku command, the i stands velocity command and V _Rrefi, denote the interstand plate speed difference vx _i in equation (1). vx _i = V _{i + 1} −v _i (1)

The deviation of the above variables from the reference value is represented by [Δ], and the basic dynamics equation is shown below. In the following equation, the first derivative with respect to time is represented by [•] and the second derivative is represented by [•].

[0010]

(Equation 1)

[0011]

(Equation 2)

By arranging the above dynamics, the model shown in FIG. 1 can be expressed by the following differential equation.

[0013]

(Equation 3)

Where a _j , b _j , c _j , d _j , e _j ,
β _j is an influence coefficient. If the state variable vector X, the output variable vector Y, and the manipulated variable vector U are respectively expressed by equations (15) to (17), the state equation (18) can be constructed.

[0015]

(Equation 4)

A state equation is constructed from the above X, Y and U,
The design method of the two-degree-of-freedom optimal servo system shown in the above-mentioned document 1 is applied. If the reference value vector Rf is represented by equation (19), the control device 10 can be represented by equations (20) and (21).

[0017]

(Equation 5)

In the present invention, since the change of the advance rate due to the pressing operation of the i stand is small (that is, in the equation (7), the variation (perturbation) due to the change δf _i of the advance rate f _{i in} the exit side plate speed is small. The effect on the output speed of the i stand is small, and the output thickness of the i stand is controlled to be almost constant. By considering as a disturbance term, the number of state variables is reduced to 6 as shown in equation (15). Further, the number of manipulated variables is three, which facilitates the design and adjustment of the control device. Further, when the control devices are arranged on a plurality of stands as shown in FIG. 2, the operation variables and the state variables do not interfere with each other, so that the control devices can be designed independently. In addition, since the follow-up characteristics of the control device can be explicitly designed, the response to the reference value is improved, and when changing the strip thickness during rolling, changing the tension between stands for the purpose of width control, and pulling out the tail end, In the small loop control for reducing the looper height and stabilizing the trailing edge slippage, high response control can be performed without impairing the stability.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a configuration diagram of a hot continuous rolling mill control device for carrying out the method of the present invention. In the figure, 1 is a looper, 2 is a stand, 4 is a material to be rolled, 5 and 6 are reduction position control devices, 7 and 8 are mill speed control devices, 9 is a looper torque control device, and 10 is the above control device. is there. 11
Is an input device, and is a roll-down position control device 6 for the i + 1 stand 3.
The rolling load P _{i + 1} and the rolling position S _{i + 1} from the looper 1
The looper angle θ _{i, the} inter-stand tension σ _i, and the looper torque T _Mi from the looper torque control device 9 are input.
Since it is difficult to measure the looper angular velocity deviation Δdθ _i / dt and the inter-stand plate velocity difference deviation Δvx _i , they are obtained by an observer.

The control device 10 calculates the deviation of each state quantity from the reference value (values of the state variable X and the output variable Y). When the reference value is represented by the subscript 0, it is defined as follows. h _{i + 1} ⁰ : Output side stand Output side plate thickness target value θ _i ⁰ : Looper angle target value dθ _i ⁰ / dt: 0 σ _i ⁰ : Inter-stand tension target value vx _i ⁰ : 0 T _Mi ⁰ : Looper torque initial setting value

At this time, the delivery stand stand-out plate thickness h _{i + 1} can be obtained by the gauge meter formula (22). h _{i + 1} = f (P _i , S _i , ...) (22)

Using the values of each state variable and output variable obtained as described above, the deviation of each manipulated variable (manipulated variable U) is calculated by the above equations (20) and (21), and each control is performed. Devices 6, 7,
By outputting to the reference value variable Rf, the output side stand output side plate thickness h _{i + 1} , the looper angle θ _i , and the stand tension σ _i are simultaneously corrected.

FIGS. 3 and 4 show the optimum values of the conventional method for the fluctuations of the outlet stand outlet plate thickness, the looper angle and the inter-stand tension when the reference value of the outlet stand outlet plate thickness is changed in this embodiment. It is shown in comparison with the regulator. FIG. 3 shows the case of the conventional method, and FIG. 4 shows the case of the method of the present invention. From these figures, it is clear that according to the method of the present invention, the follow-up characteristic to the reference value is excellent even when the plate thickness is changed during rolling.

Next, FIG. 5 shows a configuration in which the control device shown in FIG. 2 is applied to all stands. Control device 10-1
Since the operation amounts of 10 to 6 do not interfere with each other, each control device can be designed independently. Therefore, it is not necessary to extend the order of the state equation (18), and the adjustment is relatively easy.

In the above embodiment, the outlet stand outlet plate thickness is obtained from the gauge meter formula using the observer to determine the looper angular velocity deviation and the inter-stand plate velocity difference deviation, but it can be estimated or measured by other means. If there is, the estimated value or the measured value may be used. Also,
In the present invention, the control device is obtained by the two-degree-of-freedom integral optimal servo theory. However, any control device can be designed so that the control characteristic with respect to modeling error and constant value disturbance and the tracking characteristic with respect to the reference input can be designed independently. Not to mention anything.

[0026]

As described above, according to the present invention, the influence of the exit side plate speed of the entrance side stand and the exit side plate thickness (the entrance side plate thickness of the exit side stand) is treated as a disturbance, and the order of the state equation is reduced. This not only simplifies the design and adjustment of the control device, but also allows the control device to be designed without expanding the order of the state equation when applied to multiple stands. The control device obtained by applying the multivariable control theory that has clear design guidelines for the control characteristics against disturbance and the tracking characteristics with respect to the reference input allows the output stand stand-down position, the looper torque, and the input stand or exit side to be controlled. Since the mill speed of the stand is operated at the same time, there is an effect that not only the disturbance suppression characteristic but also the tracking characteristic with respect to the reference value can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a hot continuous rolling mill for explaining the method of the present invention.

FIG. 2 is a configuration diagram of a control device according to an embodiment of the present invention.

FIG. 3 is a graph showing a result when control according to a conventional example is performed.

FIG. 4 is a graph showing a result when the control according to the present invention is performed.

5 is a configuration diagram when the control device of FIG. 2 is applied to a plurality of stands.

[Explanation of symbols]

 1 looper 2 i stand 3 i + 1 stand 4 rolled material 5, 6 rolling position control device 7, 8 mill speed control device 9 looper torque control device 10, 10-1 to 10-6 control device

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B21B 37/58 B21B 37/12 BBM (72) Inventor Masamasa Kamata 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Tube Co., Ltd.

Claims (1)

[Claims] 1. A delivery side plate thickness, a looper angle, and a looper angle are controlled by using a looper torque control device arranged between stands of a hot continuous rolling mill, a mill speed control device and a rolling position control device arranged at each stand. In the method of controlling the tension between stands to the desired value, the output side thickness deviation, looper angle deviation, looper angular velocity deviation, stand tension tension deviation, interstand plate speed difference deviation, and looper torque deviation are used as state variables, and the output side stand pressure position deviation is used. In addition to setting the state equation using the indicated value, the looper torque deviation indicated value, and the mill speed deviation indicated value of the input side stand or the output side stand as the operating variables, the input side plate thickness deviation of the output side stand and the input side stand output side plate speed The output side plate velocity perturbation due to the change in the advance rate of the input side stand is used as a disturbance, and the output side plate thickness deviation, looper angle deviation and inter-stand tension deviation are Set the output equation with the difference as the output variable, and set the output side plate thickness deviation target value, looper angle deviation target value, and stand tension deviation target value as reference value variables, and control characteristics for constant value disturbance and modeling error, and reference input. With a controller obtained by the multivariable control theory that can independently design the follow-up characteristics for, the hot continuous characterized by operating the output stand pressure reduction position, the looper torque, and the mill speed of the input stand or the output stand at the same time. Method of control of rolling mill.