JPS63188416A - Control method for strip thickness and tension between stands in continuous rolling mill - Google Patents

Abstract

PURPOSE:To improve the response capability of the control system against disturbances and to improve the strip thickness and width accuracy of a stock to be rolled by optimally controlling with consideration for interference between a tension between stands, looper angle, and a strip thickness. CONSTITUTION:At the time of biting a strip 10 as a stock to be rolled by an (i+1)th stand 14, a looper 16 rises and starts a control after the looper 16 is brought into contact with the strip 10. A control computer 30 stores values of respective variables at the control starting moment (rolling load, drafting position, drafting speed, mill speed, tension between stands, looper torque, looper angular velocity, and looper angle) and calculates deviations of respective state amounts from the control starting moment. Correction amount U for respective operation values is calculated based on the above calculated deviation values and outputs the correction value U to respective controllers to concurrently correct all of an outlet side strip thickness, a tension between stands, and a looper angle.

Description

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

The present invention provides plate thickness and inter-stand tension if of a continuous rolling mill.
, II DO method, in particular, by using a torque control device, a mill speed control device, and a rolling position (or rolling speed) control device of the looper arranged between the stands of a continuous rolling mill, the looper angle is kept constant. The present invention relates to a method for controlling plate thickness and inter-stand tension in a continuous rolling mill, which controls the outlet side plate thickness and inter-stand tension to desired values while maintaining the same.

[Conventional technology]

The plate thickness and inter-stand tension in a continuous rolling mill are a system in which there is strong mutual interference, such as when the inter-stand tension increases, the plate thickness becomes thinner, and when the subsequent stand is rolled down, the mass flow is suppressed and the tension is reduced. Conventionally, inter-stand tension control and plate thickness control in continuous rolling mills have been designed independently, and by keeping the inter-stand tension constant, the inter-stand tension does not affect the plate thickness and eliminates its influence.
In addition, the tension fluctuations caused by the thick plate system were tried to be suppressed by changing the mill speed. For example, in Japanese Patent Application Laid-Open No. 52-20956, fluctuations in the exit and entry speeds of the rolled material of the first stand are calculated by the front opening of the rolling step by the plate thickness control device in the first stand, and the forward and By correcting the rear mill speed, the mass flow balance is kept constant and tension fluctuations are suppressed, and the tension between the 1st stand and the 1st + 1st stand and the tension between the 1st-1st stand and the 1st stand are kept at predetermined values. ! Disclosed is a device adapted to perform i1 m. In addition, in the special public interest publication No. 59-44129, there is a torque control system for the looper.
Using a tension control device consisting of an il+ device and a mill speed control device, the angular deviation of the looper, the angular velocity deviation, the tension deviation between stands, and the plate speed difference deviation between stands are set as state variables,
In addition, the state equation of the tension control system with the looper drive torque standard deviation and inter-stand plate speed difference standard deviation as operating variables, and the evaluation function expressed by the time integral value of the quadratic form of these deviations are set, and the above-mentioned Detect the looper angular deviation, angular velocity deviation, inter-stand tension deviation, and inter-stand plate speed difference deviation and find the value of the manipulated variable that minimizes the above evaluation function,
By correcting the reference of each 11JtIll device by m of the looper bending torque reference deviation and inter-stand plate speed difference reference deviation, the angular deviation, angular velocity deviation,
The inter-stand tension deviation and inter-stand plate speed difference deviation are fed back to the looper torque i/Jt# device and the mill speed control device to control the inter-stand tension to a desired value while keeping the looper angle constant. is disclosed.

[Problems to be solved by the invention]

However, both methods aim to control the inter-stand tension to a constant value or a desired value, and do not control the inter-stand tension and the plate thickness at the same time. or,
In the conventional method (in which tension fluctuations between stands are corrected by mill speed), the response of the mill speed control system is slower than the response of the reduction control system. This caused problems such as changes in plate thickness and width due to tension fluctuations.In particular, hydraulic reduction devices were introduced to the rolling a and 1It11 systems, and the response of the rolling u1mi system was further improved. Well, in the current situation, larger tension fluctuations are occurring, which is further exacerbating the aforementioned tendency.

Purpose of the Invention The present invention has been made to solve the above-mentioned conventional problems, and provides a continuous rolling mill that can simultaneously suppress fluctuations in tension between stands, looper angle, outlet plate thickness, etc. It is an object of the present invention to provide a method for plate thickness and inter-stand tension IIIJti11. [Means for Solving the Problems] The present invention provides a looper torque control I device, a mill speed 1 control port II device, and a rolling position (or rolling speed) control device disposed between stands of a continuous rolling mill. Using this, the exit plate thickness and inter-stand tension can be controlled to desired values while keeping the looper angle constant +-! As shown in Fig. 1, the looper angle deviation, looper angular velocity deviation, looper torque deviation, tension deviation between stands, mill speed deviation, exit side plate thickness deviation (and rolling speed deviation) are set as state variables. Then, a state equation is set with the looper drive torque standard deviation, mill speed standard deviation, and standard deviation (rolling lower position or rolling speed) as operating variables, and the looper angle deviation, inter-stand tension deviation, and outlet side plate thickness deviation are output. Set the output equation as a variable, find the value of the manipulated variable that minimizes the evaluation (illli function) expressed by the time integral value of the quadratic form of the output variable, and calculate the obtained looper drive torque standard deviation, mill speed standard By correcting the standard of each control 20 device by the difference between the deviation and the rolling position (or rolling speed) reference Q, and simultaneously operating the rolling position (or rolling speed) in addition to the looper drive torque and mill speed, This has achieved the 110th purpose. (Function) FIG. 2 shows the looper 16 and rolling stands 12 <wr stand) and 14 (i-th stand) in a general continuous rolling mill.
+1 stand), and 10 is the material to be rolled. Here, in order to simultaneously explain the two inventions according to the present application, the first stand 12 is equipped with a rolling down speed control device (not shown) having the electric rolling bag d as the operating end, and
It is assumed that the 1 stand 14 is equipped with a reduction speed control device (not shown) whose operating end is a hydraulic reduction device. Furthermore, each rolling mill stand 12, 14 is equipped with a speed control device (not shown), and the looper 16 is equipped with a looper torque control 2Ug position (not shown). Here, the rolling position of the 1st stand and the i+l stand are respectively S i s Sill, the looper angle is θi, the looper angular speed is N i , the looper torque is 11 rolling speed is V sf % the rolling position reference is S Ri , the mill Speed r! !
Also (standard is V Ri % looper drive torque reference is fJRi
In other words, the inter-stand tension σi and the exit plate thickness hf s h ill of each stand in FIG. 2 are expressed by a differential equation (not shown below). Δh t=Kt/ (Mi+Ki) ・ΔVs i-,
(1) ΔVsi=-(1/Ts i )"ΔVsi+
(Ks i/Ts i) ・ΔSpi・・・・・・
...(2) ΔVi= (1/Tvi)・ΔVi + (Kvi/Tvi) ・ΔVRi・=(3)
Δ0'1=-k hi ・Δll i k v i
'ΔVi+k h i, 1'' Δ h ill
+ k v ill ” ΔV i
+1+ksi・ΔN1−kr iΦΔVi・・・・・・
...(4) ΔQi--(1/Tgi) ・ΔUi +(Kgi/Tgi>・Δ(lRi...(5) ΔN1
= (1/J)・Δgi 1lri′・Δσ1kN(-
・ΔNike+−・Δθi・・・・・・・・・(6
) Δθ1−Ni ・・・・・・・・・
(7) Δb i, lx − (1/Ts+, +) #Δh
+ (Ks;++/Ts;, +)#ΔS Rr-+
−(8) ΔVi, +−−(1/Tv+, +) ・ΔV
i+1+ < K v ill / T v ill
) 4ΔV I? , -+ - < 9) where, Δhi: i-th stand outlet side Itahara deviation, ΔVsi: 1st-stand rolling speed deviation, Δ■i: i-th stand mill speed deviation, Δσi: i-th stand tension deviation, Δgi: i-th looper 8th looper torque deviation i: Ni: 8th looper angular velocity deviation 1: i-th looper 8th looper angular deviation i and 1: i-th + 1st stand outlet side plate thickness deviation, ΔV i
ll: i+1st stand mill speed tin difference, ΔSRi: i-th stand pressure lower @ standard deviation, ΔVRi: i-th stand mill speed standard deviation, ΔgRi: i-th looper drive torque standard deviation, Ki: i-th stand mill constant, Mi : i-th stand plastic constant, K: gain of manipulated variable, Tα: time constant, kb: influence coefficient from fi to Δσi near steady state, kC-: near steady state from factor C to Ni is the influence coefficient of Note that the deviation in J3 in the above equation is the deviation of each variable from the control start point, and [.] means the time differential [d/d]. Here, if X, Y, and U are state variables, output variables, and manipulated variables, respectively, equations (1) to (9) are expressed by the following equations. Here, X=<Δh i , ΔVs+ , AVi , Δ(
7i. Δ g ++ Δ N+, Δ θ i , Δ h
tel l ΔVr◆+)−Y=(Δhi,
Δσ1 , Δθi , Δh ++1 ) −U−(ΔS
p+, ΔVRi, ΔORi. ΔSR++1, ΔVR++1
) − is. Note that [′] means transposition of a vector. In the present invention, the evaluation function J -f(Y=・Q−Y+U′・R−Ll) dt・・
・・・・・・・・・(11) Here, by finding the optimal pre-control U that minimizes Q: non-negative definite matrix R: positive definite matrix, stable inter-stand tension with good responsiveness and exit plate JV can be obtained. control. Note that U is constructed from the following equation when using an integral control method for an optimal control system. U −−F−X+f,' K ・(Yo−Y) dt
(12) Here, F, IK: constant matrix Yo: target value of output variable. The trough BmX and the output Y in this equation (12) may be either actually measured values or estimated values. For example, the outlet side plate thickness may be estimated by installing a thickness gauge on the outlet side of each stand, but also by the following formula based on the gauge meter formula. Δh,=r(ΔSj, ΔPatΔVJ,...)・
(13) Here, ΔPJ is the rolling load deviation. In addition, the first invention and the second invention of the present application are based on the difference in the selected rolling down device (rolling down speed control device or rolling down speed control device), and the above equations (1), (2) and (8). The difference is which one to use. The reason why there is no need to use the rolling position deviation as a state variable in the present invention is because it can be determined from the outlet side plate thickness.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 shows the overall configuration of the inter-stand tension control device and exit side plate thickness control device for carrying out this embodiment. In the figure, 20.22 is the mill speed control device, 24 is the looper torque control 20 device, and 26 Reference numeral 28 denotes a reduction speed control device including an electric reduction device, 28 a reduction position control device 9Il including a hydraulic reduction device d, and 30 a control computer. In this apparatus, when the strip 10, which is the material to be rolled, is caught in the i+1-th stand 14, the looper 16 rises and comes into contact with the strip 10, after which control is started. The control computer 30 stores the fil of each variable at the start of control.
(pressure, t load m P i , P country, pressure lower 1s t
, S;-+. Reduction speed V S f s Mill speed V I N V il
1, inter-stand tension σi, looper torque 0.11, looper angular velocity Ni1, looper angle θi), and calculate the deviation of each state quantity from the start of control (output fill plate thickness deviation Δhl, Δ
hi++, rolling speed deviation ΔV s i 1 mill speed deviation ΔVi, ΔV ill, tension deviation Δσ1, looper torque (12 difference ΔO1, looper angular velocity deviation ΔN i , looper angle deviation Δθ1) are calculated. At this time, the exit side plate thickness deviation Δ
hi and ΔIf ill can be obtained from the above equation (13). Using the obtained deviation of the state quantity, the correction maximum U of each operation W (rolling position correction amount ΔS n I
, A S Rid , Mi/L/speed correction taΔVRi
, ΔV RDI, looper torque correction port ΔgRi) and outputs them to each control device, the exit side plate thickness h
id, inter-stand tension σi, and looper angle θi are simultaneously corrected. FIG. 4 shows the plate thickness I on the exit side of the 1st + 1st stand when the target value of the plate thickness on the exit side of the 1st + 1st stand is changed in this example.
The figure shows the variation in till and the inter-stand tension σi in comparison with the conventional example. An example of a conventional example is the 1985 Tokushu Publication Corporation, which applied optimal control only to the tension between stands and the looper system.
The case of 44129 is adopted. From FIG. 4, it is clear that by the method of the present invention, the exit side plate thickness can be controlled to a desired value without causing tension fluctuations between stands. In addition, in the above embodiment, the case where the number of stands is 2 was explained as an example, but 1)) The Δ, B, and C matrices of equation (10) can be expanded in the same manner as in the case of 2 stands. Therefore, it is clear that the present invention can be similarly applied to a continuous mill with three or more stands. Also, if the i+lth stand is the final stand,
It is also possible to exclude the mill speed of the i+1th stand as a manipulated variable through subsequent steps such as winding.

【Effect of the invention】

As explained above, according to the present invention, the tension between the stands,
Optimal control is performed by strictly considering the mutual interference between the looper angle and plate thickness, so even in systems where there is strong mutual interference between the tension between the stands, the looper angle, and the outlet side plate thickness, the control system's responsiveness to disturbances is improved. Significantly improved. Therefore, it has the excellent effect of improving the plate thickness and plate width accuracy of the rolled material.

[Brief explanation of the drawing]

FIG. 1 is a flowchart without showing the gist of the method for controlling plate thickness and inter-stand tension in a continuous rolling mill according to the present invention, FIG. 2 is a diagram for explaining the present invention in detail, and FIG. FIG. 4 is a diagram showing the structure of a stand IN tension and plate thickness control device for carrying out an embodiment of the present invention, and FIG. 4 is a diagram showing the response of the control system according to the present invention in comparison with a conventional example. . 10... Rolled material (strip), 12.14... Rolling stand, 16... Looper, 20.22... Mill speed control device, 24... Looper torque control device, 26... Rolling down speed control device, 28... Rolling down speed control device, 30... Control computer, X... State variable, Y... Output variable, U... Manipulated variable, J... Evaluation function, σi...tension between stands, θi...looper angle, h i, h, Yabi...exit side plate thickness, Δθi...looper angle deviation, ΔNi...looper angular velocity deviation, 6g1...looper torque deviation , Δσi... Tension deviation between stands, ΔVi... Mill speed deviation, Δtli... Output side plate thickness deviation, ΔS Ri, ΔS Ri+1... Rolling position correction, Δ
V Ri sΔV Rill... Mill speed correction m1Δ
R1...During looper torque correction.

Claims (2)

[Claims] (1) Using a torque control device, a mill speed control device, and a control device at the rolling position of the looper placed between the stands of a continuous rolling mill, the desired exit plate thickness and inter-stand tension are achieved while keeping the looper angle constant. When controlling the value, the looper angle deviation, looper angular speed deviation, looper torque deviation, inter-stand tension deviation, mill speed deviation, and outlet side plate thickness deviation are used as state variables, and the looper drive torque standard deviation, mill speed standard deviation, and rolling position standard deviation are used as state variables. At the same time as setting a state equation in which the operating variables are the looper angle deviation, inter-stand tension deviation, and exit plate thickness deviation as output variables, The value of the manipulated variable that minimizes the evaluation function is calculated, and the reference of each control device is corrected by the amount of the obtained looper drive torque standard deviation, mill speed standard deviation, and rolling position standard deviation. A method for controlling plate thickness and tension between stands in a continuous rolling mill, characterized by simultaneously controlling speed and rolling position. (2) Using the torque control device, mill speed control device, and rolling speed control device of the looper placed between the stands of the continuous rolling mill, the exit side plate thickness and the tension between the stands are set to the desired value while keeping the looper angle constant. When controlling, the looper angle deviation, looper angular velocity deviation, looper torque deviation, inter-stand tension deviation, mill speed deviation, exit side plate thickness deviation, and reduction speed deviation are used as state variables, and the looper drive torque standard deviation, mill speed standard deviation, and reduction Setting a state equation in which the speed standard deviation is an operating variable, and setting an output equation in which the looper angle deviation, inter-stand tension deviation, and exit plate thickness deviation are output variables, and calculating the time integral of the quadratic form of the output variables. Find the value of the manipulated variable that minimizes the evaluation function expressed as a value, correct the standards of each control device by the amount of the found looper drive torque standard deviation, mill speed standard deviation, and rolling speed standard deviation, and then A method for controlling plate thickness and tension between stands in a continuous rolling mill, characterized by simultaneously controlling torque, mill speed, and reduction speed.