JPH0472603B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling the crown and flat shape of a rolled material in a continuous rolling mill. More specifically, the present invention relates to a feedback control method for a continuous rolling mill in which the operation amount of the rolling mill is changed based on the measured values of the crown and flat shapes, and these are simultaneously controlled to respective target values.

(Prior art) Accurate control of the crown and flat shape (hereinafter referred to as shape) of a rolling mill for steel plates, etc. during continuous rolling is important not only to maintain the quality of the rolled material but also to avoid trouble during rolling. is important. For this reason, a roll bending device or a variable crown roll is provided in each stand of a continuous rolling mill, and the amount of operation thereof is adjusted in each stand to control the crown and shape to target values.

However, even if the amount of operation of each stand is changed, the crown and shape cannot be controlled independently. Therefore, both controls interfere. Therefore, it is difficult to control the crown and shape to target values at the same time.

Therefore, Japanese Patent Application Laid-open No. 126310/1983 discloses that in a continuous rolling mill, any stand except the final stand is provided with a roll bending device to function as a plate crown control stand, and the final stand is used to detect the plate crown on the exit side. The value is fed back to the roll bending device of the plate crown control stand, and the pressure of the roll bending device is controlled to eliminate the difference between the detecting plate crown, the target plate, and the crown, and the plate crown is controlled within the shape dead zone. However, it has been proposed to detect the shape of the plate at the exit side of the final stand, feed back the value to the roll bending device of the final stand, and control the pressure of the roll bending device to control the shape of the plate.

However, even in the control method proposed in this publication, the plate shape control at the final stand is not non-interfering control, so in the process of controlling the plate shape to the target value, it interferes with the crown, causing the crown to deviate from the target value.

On the other hand, for example, Japanese Patent Laid-Open Nos. 57-124510 and 59-47006 propose non-interferential control of the crown and shape in the last two or three stands.

However, in the control methods proposed in these latter two publications, the control range is narrow because feedback control is performed only at the last two or three predetermined stands. Therefore, if the crown or shape deviates significantly from the set value before the rolled material reaches the final predetermined number of stands, non-interference control can be used to simultaneously correct the crown and shape to the target value using only the final predetermined number of stands using feedback control. Control becomes impossible.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to modify the crown and shape of the exit side of the final stand over a wide range in a non-interfering manner, thereby simultaneously modifying them. It is an object of the present invention to provide a crown/shape control method for a continuous rolling mill that can control the crown shape to a target value.

(Means for solving the problem) In order to achieve the above-mentioned object, the present inventors have conducted repeated research, performed crown feedback control that does not affect the shape in all stands of a continuous rolling mill, and In this way, we came up with the idea of performing shape feedback control that does not affect the final stand exit crown in a predetermined number of stands, the final two or more.

Thus, the gist of the present invention is to measure the plate crown and shape of the rolled material at the outlet side of the final stand, and to adjust the plate crown and shape at the outlet side of the final stand to respective target values through feedback control based on these measured values. In the strip crown/shape control method in the continuous rolling mill to be controlled, (a) the deviation of the actual value of the strip crown at the exit side of the final stand from the target value is calculated, and (b) the deviation of the strip crown at the exit side of the final stand is set to 0. and (c) calculate the amount of crown correction for each stand exit side that makes the amount of correction of the crown ratio on the exit side of each stand equal for all stands based on the deviation calculated in (a) above, and (c) for each stand. Calculate the operation amount (crown feedback operation amount) of each stand necessary to correct the crown amount of each by the correction amount calculated in (b) above, and (d) the shape at the exit side of the final stand. (e) Calculate the deviation between the actual measurement value and the target value; (f) For stands other than the final predetermined number of stands, the total amount of operation is the amount of operation calculated in (c) above, and for the final predetermined number of stands, the above ( A sheet crown/shape control method in a rolling mill comprising controlling each stand using the sum of the manipulated variables calculated in c) and (e) as the total manipulated variable.

At this time, it is preferable to correct the total operating amount of each stand in synchronization with the rolling load variation or material deformation resistance variation in each stand, thereby eliminating crown variation and shape variation.

In addition, the amount of crown correction on the exit side of each stand calculated and determined in the step (b) above includes not only the amount of correction of the crown amount itself, but also the amount of correction of an amount equivalent to the crown amount, such as the crown ratio, etc. Can be used.

(Function) The operation amount of the crown feedback control in all the stands of the rolling mill is determined by the steps (a), (b), and (c) above.

Amount of change (correction amount) in the crown ratio on the exit side of each stand caused by the operation amount determined in step (c)
is equal in all stands due to the conditions in step (b). Therefore, this amount of operation hardly affects the shape of the rolled material. The reason for this will be explained in detail below.

On the other hand, the operation amount for shape feedback control in the final predetermined number of stands is determined in the steps (d) and (e) above. This operation amount does not affect the crown on the exit side of the final stand due to the conditions of step (e).

The manipulated variables for crown control determined in (a), (b), and (c) and the manipulated variables for shape control determined in (d) and (e) are superimposed in step (f). and used.

Therefore, the crown and the shape are simultaneously controlled to the target values. At this time, crown control and shape control do not interfere with each other. Moreover, since crown control is performed on all stands, the crown and shape can be controlled over a wide range without interference.

(Embodiments) Next, embodiments of the present invention will be described in detail by item with reference to the accompanying drawings. Figure 1 shows
1 is a block diagram showing the configuration of a continuous rolling mill for steel plates having six stands to which the present invention is applied; FIG.

(A) Definition of crown and shape Steel plate 1 is rolled on the first to sixth stands,
Exit crown c ₁ ,..., c ₆ and exit shape S ₁ ,...
It becomes _S6 . Note that the first stand entry side crown and entry side shape are represented by c ₀ and S ₀ , respectively.

The crown c and the shape (difference in elongation rate) S are given by the following equations.

c=h _c −h _e ……(1) S=(l _c −l _e )/l _c ……(2) Here h _c = Thickness at the center of the plate h _e = Thickness at the edge of the plate (thickness at both ends (average value) l _c = Length of the center of the plate in the longitudinal direction l _e = Length of the edge of the plate in the longitudinal direction (average value of both ends) (see Figure 2).

(B) Relationship between operation amount, crown, and shape Each stand is equipped with a roll bending device or a variable crown roll. The adjustment amounts ΔU ₁ , . . . , ΔU ₆ of the roll bending force or variable crown amount of each stand are the manipulated variables in the control according to the present invention. The amount of change in the crown on the exit side of each stand caused by these operating amounts is Δc ₁ , ..., Δc ₆ , and the amount of change in the shape on the exit side is Δs ₁ , ...,
Expressed as Δs ₆ , the relationship between these quantities and the manipulated variable is
As is well known, the following relationship holds true.

ΔS _i =a _i ΔS _i-1 +b _i (Δc _i /h _i −Δc _i-1 /h _i-1 ) ...(3) Δc _i =f _i Δc _i-1 +g _i ΔU _i ...(4 ) where i=1,...,6, and a _i , b _i , f _i , g _i are: a _i : Front stand shape influence coefficient b i : Crown ratio shape influence coefficient f _{i :} Front stand crown influence coefficient g _i : Manipulated variable crown influence coefficient, which is a constant under certain rolling conditions. Further, h _i is the thickness of the central portion of the steel plate at the exit side of the i-th stand. (If the amount of change in the first stand entrance side crown and shape is expressed as Δc ₀ and Δs ₀ , respectively, equations (3) and (4) are also valid even when i = l.) (C) Operation amount for crown control Book In the invention, feedback control of the crown is performed in all stands. Calculation of the manipulated variable for this crown correction control will be explained in detail.

Deviation calculation The crown detector 2 detects the crown _c6 on the exit side of the final stand. The deviation Δc is calculated as the difference between the measured crown c ₆ and the target value c _x using the following equation.

Δc＝c ₆ −c _x ...(5) Crown correction amount calculation Correction amount Δc ₁ of the exit crown of each stand,
..., Δc ₆ is determined by solving the following equation.

Δc ₆ = −Δc ……(6) Δc ₁ / h ₁ = Δc ₂ / h ₂ = Δc ₃ / h ₃ = Δc ₄ / h ₄ = Δc ₅ / h ₅ =
Δc ₆ /h ₆ ...(7) Here, h _i is the thickness of the central part of the steel plate at the exit side of the i-th stand, as in the case of equation (3),
It can be regarded as a constant. Equation (7) expresses the condition that the ratio correction amounts are all equal on the exit side of each stand.
Furthermore, equation (6) represents the conditions for eliminating the deviation calculated by equation (5).

Operation amount calculation Operation amount ΔU _1C of each stand for crown feedback control in all stands,
..., ΔU _6C is calculated by substituting the crown correction amounts Δc ₁ , ..., Δc ₆ calculated in this section (C) into the above equation (4). That is, if the first stand entrance side crown does not change (Δc ₀ =0), then from equation (4) (i = 1, ..., 6), Δc ₁ =g ₁ ΔU _1C ... (8-1 ) Δc ₂ =g ₂ ΔU _2C +f ₂ Δc ₁ ...(8-2) Δc ₃ =g ₃ ΔU _3C +f ₃ Δc ₂ ...(8-3) Δc ₄ =g ₄ ΔU _4C +f ₄ Δc ₃ ... (8-4) Δc ₅ = g ₅ ΔU _5C + f ₅ Δc ₄ ... (8-5) Δc ₆ = g ₆ ΔU _6C + f ₆ Δc ₅ ... (8-6) Simultaneous equations (8-1) ~ ( By substituting the values of Δc ₁ , . . . , Δc ₆ into 8-6), each operation amount ΔU _1C , . . . ΔU _6C for crown correction control is calculated.

Crown and shape modification amount due to calculated manipulated variable Manipulated amount ΔU _1C for crown modification control,
……, each stand exit crown according to ΔU _6C
The correction amounts Δc ₁ , . . . , Δc ₆ of _{c 1} , . . . , c ₆ satisfy the above equations (6) and (7).

Depending on the amount of operation, each stand exit shape S ₁ ,...
..., S ₆ does not change. This is because, assuming that the first stand entrance shape S ₀ does not change,
This is because from the above equation (3) (i=1, ..., (6) and (7), ΔS _i =0 (i=1, ..., 6). Therefore, the manipulated variable depends on the shape. No impact.

(D) Manipulation amount for shape control In the present invention, shape feedback control is carried out by controlling the crown feedback in a predetermined number of final two or more stands. In the embodiment shown in FIG. 1, shape feedback control is performed in the last two stands (fifth and sixth stands).
Calculation of the manipulated variable for shape modification control will be explained below.

Deviation calculation Shape detector 3 detects the shape of the exit side of the final stand.
Detect S ₆ . The deviation ΔS is this measured shape S ₆
The difference between the target shape S x and the target shape S _x is calculated using the following equation.

ΔS=S ₆ −S _x ...(9) Operation amount calculation Crown caused by operation amounts ΔU _5S and ΔU _6S (hereinafter expressed as ΔU ₅ and ΔU ₆ in this section) for shape correction in the final two stands If the correction amount of is expressed as Δc _0S , ..., Δc _6S , and the correction amount of shape is expressed as ΔS _0S , ..., ΔS _6S (hereinafter in this section, Δc ₀ , ..., Δc ₆ and ΔS ₀ ,
..., represented by ΔS ₆ ) Naturally, Δc ₀ = Δc ₁ = Δc ₂ = Δc ₃ = Δc ₄ = 0 ...(10) ΔS ₀ = ΔS 1 = ΔS ₂ = _{ΔS 3 =} ΔS ₄ = 0 ...( 11). Also, since it is necessary not to affect the crown on the exit side of the final stand, Δc ₆ = 0 ...(12) Furthermore, ΔS ₆ should eliminate the deviation ΔS obtained in this section, so ΔS ₆ = -ΔS ...(13) must be satisfied.

Therefore, the following relationship holds between the amount of operation in the final stand and the amount of correction of the crown and shape resulting from this, based on equations (3) and (4) above.

ΔS ₅ = (b ₅ /h ₅ )・Δc ₅ ...(14) Δc ₅ =g ₅ ΔU ₅ ...(15) ΔS ₆ =a ₆ ΔS ₅ +b ₆ (Δc ₆ /h ₆ −Δc ₅ /h ₅ )=-ΔS
...(16) Δc ₆ =f ₆ Δc ₅ +g ₆ ΔU ₆ =0 ...(17) From equations (14) and (15), ΔS ₅ = (g ₅ b ₅ /h ₅ )・ΔU ₅ (18) Therefore, by substituting this equation (18) into ΔS ₅ in equations (16) and (17) and solving for ΔU ₅ and ΔU 6, _{ΔU 5} = αΔS ……(19) ΔU ₆ = βΔS ……(20 ) is obtained. (Here, α and β are constants expressed by fractional functions such as constant coefficients b ₅ , h ₅ , g ₅ in equations (14) to (17). The specific form of this fractional function is (16 )
It is easily determined by solving equation (18). ) Amount of crown and shape modification caused by calculated manipulated variables Crown modification amount (change amount) caused by shape modification manipulated variables ΔU _5S and ΔU _6S
satisfies equations (10), (15), and (12).

The amount of correction (amount of change) of the shape caused by the operation amount satisfies equations (11), (18), and (13).

(E) Total operation amount Calculation of total operation amount The total operation amount for each stand is obtained by superimposing the operation for crown control in section (C) and the operation amount for shape control in section (B). That is, the first to fourth
At the stand, ∆U ₁ = ∆U _1C ... (21-1) ∆U ₂ = ∆U _2C ... (21-2) ∆U ₃ = ∆U _3C ... (21-3) ∆U ₄ = ∆U _4C ... (21-4) ) Also, for the fifth and sixth stands, it is calculated as follows: ΔU ₅ = ΔU _5C + ΔU _5S (21-5) ΔU ₆ = ΔU _6C + ΔU _6S (21-6).

Although the shape correction stands in the embodiment are the last two stands, it is also possible to have three or more stands.

Amount of modification of the crown and shape caused by the total amount of operation Amount of modification (amount of change) of the crown and shape of each stand exit side caused by the total amount of operation given by equations (21-1) to (21-6) teeth,
It is given by the sum of the correction amount due to the manipulated variable for crown control in term (C) and the correction amount due to the manipulated variable for shape control in term (D).

Therefore, when the total operation amount is fed back at each stand, there is no interference between the two, and c ₆ and S ₆ on the exit side of the final stand are the target values c _x and S _{x ,} respectively.
controlled by.

(F) Synchronous Control to Eliminate Disturbances As described above, by superimposing crown and shape feedback control, it is possible to set both the crown deviation and shape deviation to 0 if no disturbance occurs.

However, in actual rolling, crown fluctuations and shape fluctuations occur due to disturbances such as fluctuations in rolling load or fluctuations in deformation resistance due to skid marks caused by material heating.

In such a case, the total operation amount ΔU ₁ , ..., ΔU ₆ of each stand calculated in section (E) is further superimposed with the operation amount for eliminating the disturbance to eliminate crown fluctuations and shape fluctuations caused by the disturbance. It is preferable to do so. Synchronous control for eliminating this disturbance will be explained below.

Calculation of operation amount to eliminate disturbance For example, rolling load at the i-th stand
Suppose that P _i fluctuates by ΔP _i and acts as a disturbance, thereby causing a crown fluctuation Δc _ix . That is, for each i=1, . . . , 6, Δc _ix =γ _i ·ΔP _i (22) with γ _i as a constant.

Let the amount of operation of the i-th stand to eliminate the crown fluctuation be U _ip , and the amount of crown correction on the exit side of each stand caused by this will be Δc _ip
Since the manipulated variable should eliminate the crown fluctuation, it must satisfy Δc _ip =−Δc _ix (23).

On the other hand, from equation (4), if the operation amount of stands other than the i-th stand is 0, Δc _ip = giΔU _ip ... (24) Therefore, from equations (22), (23), and (24), ΔU _ip =−(γ _i /g _i )ΔP _i (25) As shown in FIG. 1, the rolling load p _i is detected by a load cell in each stand.
Therefore, by substituting the detected rolling load variation into equation (25), the operation amount ΔU _ip for eliminating the crown variation is calculated.

Superposition of manipulated variables for eliminating disturbances The manipulated variables for eliminating disturbances calculated in this section (F) are further superimposed on the total manipulated variables calculated in section (E).

In the case of only feedback control using the manipulated variable in item (E) above, the crown and shape remain subject to fluctuations that approach the absolute target value on average (see graph Y in FIG. 3). In addition to this section,
When the manipulated variables calculated in (F)) are superimposed, the crown weight shape absolutely approaches the target value without any fluctuation (see graph X in Figure 3).

Note that the method described in (F) is a method for eliminating crown fluctuations at the current stand, but feedforward control that eliminates them at the next stand is also possible.

Furthermore, crown control is performed using a preset output based on the setup calculation and a synchronized output for the fluctuations during rolling calculated in this section (F).
It is also possible to perform stable crown shape control by performing shape control without affecting the crown using two or more subsequent stands.

(G) Modification due to time delay, etc. It is preferable to modify the operation amount for crown feedback control and shape feedback control in consideration of the dead time of material movement. Further, it is preferable to stabilize the control by setting an appropriate gain.

(Effect of the invention) In the present invention, crown feedback control is performed in all stands of a continuous rolling mill, and the final
Shape feedback control that does not interfere with crown control is performed using the above multiple stands.

Therefore, according to the present invention, the crown and shape can be controlled simultaneously and non-interferingly over a wide control range. Furthermore, by superimposing feedback control on disturbances, it is possible to produce strips with good crown and shape quality, and the yield rate is also improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining an embodiment of the present invention; FIG. 2 is a perspective view for explaining the crown and shape of a steel plate (rolled material); and FIG.
The figure is a graph showing variations in crown deviation and shape deviation with respect to target values in feedback control according to the present invention. 1: Steel plate, 2: Crown detector, 3: Shape detector.

Claims (1)

[Claims] 1. A continuous process in which the plate crown and shape of the rolled material are measured at the outlet side of the final stand, and the plate crown and shape at the outlet side of the final stand are controlled to respective target values through feedback control based on these measured values. In a strip crown/shape control method in a rolling mill, (a) the deviation of the measured value of the strip crown at the exit side of the final stand from the target value is calculated; (b) the deviation of the strip crown at the exit side of the final stand is set to 0, and Calculating the amount of crown correction on the exit side of each stand to make the amount of correction of the crown ratio on the exit side of each stand equal for all stands, based on the deviation calculated in (a) above; (c) Crown amount of each stand (d) Calculate the deviation between the actual shape value and the target value at the exit side of the final stand. (e) Calculating the operation amount of a predetermined number of final stands of 2 or more with the shape deviation on the exit side of the final stand set to 0 and the amount of crown on the exit side of the final stand not changed; (f) The final predetermined number For stands other than the stand, the total operation amount is the operation amount calculated in (c) above, and for the final predetermined number of stands, the sum of the operation amounts calculated in (c) and (e) above is the total operation amount. A method for controlling each stand as a quantity, and a plate crown/shape control method in a rolling mill. 2. The rolling according to claim 1, wherein the operation amount of each stand is corrected in synchronization with the rolling load variation or material deformation resistance variation in each stand, thereby eliminating crown variation and shape variation. Method for controlling plate crown and shape in machine.