JPH08112609A - Method for controlling width in hot rolling - Google Patents

Abstract

PURPOSE: To improve the control accuracy of width control in hot rolling. CONSTITUTION: The variation of width in a finishing mill group F1-F7 is predictively calculated by a predicting formula of width variation and, based on this calculated value and target width on the outlet side of the finishing mill group, the manipulated variables of edgers E4-E6 provided in the vicinity of the roughing mills R4, R5 and/or the finishing mill group are controlled. In such a case, the variation ΔCr of crown ratio that the crown ratio Crin on the inlet side is deducted from the crown ratio Crout on the outlet side is determined as to each rolling stand and also the width variation is predictively calculated applying the formula of width variation in the vicinity of roll bite that is expressed by, when ΔCr<=0, a functional formula: ΔWrb/W= f(ΔCr), when ΔCr>=0, the functional formula: ΔWrb/W=g(ΔCr,σb , σo ). (ΔWrb: the variation of width in the vicinity of roll bite, W: width, σb : the tension on the inlet side, σo : deformation resistance.)

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip width control method in hot rolling, and more particularly to a strip width control method in hot rolling capable of highly precise strip width control.

[0002]

2. Description of the Related Art Conventionally, as a strip width control method for a hot finish rolling mill, a strip width variation amount in a finish rolling mill group is measured or calculated, and the tension between stands is changed based on the measured value or the calculated value. To control the board width (for example,
JP-B-3-24283, JP-A-1-262011, JP-A-5-285517), the material to be rolled by controlling the opening of an edger rolling machine installed on the entrance side or inside of the rough rolling mill group or finish rolling mill group. For controlling the width of the sheet (for example, Japanese Patent Laid-Open No. 62-
296904, JP-A-63-299807, JP-A-5-
285516) and the like are known.

In order to perform the strip width control with high accuracy, it is necessary to clarify the strip width change behavior in the finishing rolling mill group, and various studies have been conducted from the past, and it has been attempted to apply the results to an actual mill. Has been done. As the findings so far, as conceptually shown in FIG. 17, phenomena such as width shrinkage due to tension between stands, width expansion in roll bite, width shrinkage on roll bite entry side, etc. have been widely confirmed. In particular, recently, some research results have shown that the width change behavior in the roll bite and in the vicinity of the roll bite including the entry side of the roll bite have a proportional relationship with the change of the crown ratio in rolling (for example, the 42nd plastic working lecture. Proceedings, 19
91, p 315-318).

[0004]

However, the plate width change prediction formulas proposed so far have not been able to make accurate predictions. It is considered that the cause of this is that the strip width change behavior in the finishing rolling mill group has not been sufficiently clarified.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a strip width control method in hot rolling capable of performing strip width control with higher accuracy than in the past. .

[0006]

Means for Solving the Problems The present invention predicts and calculates a strip width change amount in a finishing rolling mill group by a strip width variation predicting equation, and based on the calculated value and a target strip width on the exit side of the finishing rolling mill group, In the strip width control method in hot rolling in which the operation amount of the strip width control means provided in the vicinity of the rough rolling mill and / or the finishing rolling mill group is controlled, each rolling stand is input from the crown ratio Cr _out on the exit side. The crown ratio change ΔCr is obtained by subtracting the crown ratio Cr _in on the side, and when ΔCr ≦ 0, the functional formula: ΔWrb / W = f (ΔCr), and when ΔCr ≧ 0, the functional formula: ΔWrb / W = g (ΔCr, σ _b , σ _o ) (ΔWrb: change in plate width near the roll bite, W: plate width, σ
_The above problem is solved by applying a plate width change expression in the vicinity of the roll bite represented by _b : entrance side tension, σ _o : deformation resistance) to predictively calculate the plate width change amount.

According to the present invention, the plate width change formula near the roll bite is expressed as follows: ΔWrb / W = ΔCr in the case of ΔCr ≦ 0, ΔWrb / W = (1-α · σ _{b in} the case of ΔCr ≧ 0 / Σ _o ) ΔCr (α: constant).

According to the present invention, when calculating the change in the crown ratio, the predicted value of the plate crown after being processed by the plate width control means, the target crown of the finishing rolling mill group, and the stand-side plate crown of each stand. The estimated value or the set value of is used.

In the present invention, the strip width control means is an edger rolling mill.

[0010]

The inventors of the present invention, in order to clarify the behavior of the strip width change in the finishing rolling mill group, the tension rolling experiment of the aluminum coil using the test rolling mill for research, the hot creep test, and the operation data in the actual rolling mill. As a result of detailed research through analysis of the above, new knowledge was obtained as described below regarding the behavior of plate width change.

The present invention has been made based on this knowledge, and according to the present invention, it has become possible to highly accurately predict the amount of change in strip width in a finishing rolling mill group, which has heretofore been impossible. First, the result of a tension rolling experiment of an aluminum coil, which was carried out for the purpose of investigating the width change behavior near the roll bite, will be described.

Two-stage rolling mill for experiment (diameter 310 mm x length 3
00mm), an aluminum coil (plate thickness H = 1 or 2mm, plate width W = 200mm) is rolled while applying tension, and an inlet / outlet side tension (0.0 to 4.0 kgf / mm ² ), a reduction rate (10%, Three
0%, 50%) and the influence of the change in plate crown ratio on the change in width near the roll bite were investigated.

The plate crown was adjusted by changing the initial crown of the work roll. Usually, the plate crown is defined by the difference between the representative point in the width direction and the plate thickness at the center. However, here, the crown ratio Cr is defined by the following equation (1) so that the difference in plate profile can be taken into consideration.
FIG. 4 shows a conceptual diagram for explaining the relationship between the crown ratio, the plate width, and the plate thickness.

[0014]

[Equation 1]

Here, W is the plate width, z is the width direction position, h is the plate thickness at the width direction z position, and hc is the plate thickness at the center of the plate width.
Further, the change ΔCr in the crown ratio is ΔCr = when the crown ratios on the input side and the output side are Cr _in and Cr _out , respectively.
Defined by Cr _out- Cr _in .

Further, in the plastic deformation region, the volume conservation law which can be expressed by the following equation (2) with respect to the deviation from the strain at the arbitrarily determined reference position is established.

Δε _h + Δε ₁ + Δε _w = 0 (2) Δε _h : Strain deviation in the thickness direction Δε ₁ : Strain deviation in the rolling direction Δε _w : Strain deviation in the strip width direction

Further, as shown in FIG. 5, the width strain ε at the center of the plate width
_{Based on wc} , the width distortion ε _w is expressed by the following equation.

Ε _w = ε _wc + Δε _w (3)

Therefore, the width change ΔWrb near the roll bite
Is the sum of the component due to the width distortion in the central part of the plate width (hereinafter referred to as the central component) and the deviation component from the central part of the plate width (hereinafter referred to as the deviation component) as in the following equation (4). Can be represented by However, in this equation (4), the whole is divided by the plate width W, and the left side is represented by the width change rate.

[0021]

[Equation 2]

Assuming that the strain deviation in the rolling direction, which appears as a change in shape, is small (Δε _l ≈0), Δε _w = −Δε _h from the above equation (2), so the deviation component of the above equation (4) is It can be expressed by the following equation (5) using the change in crown ratio ΔCr.

Therefore, the above equation (4) can be expressed by the following equation (6).

[0024]

(Equation 3)

ΔWrb / W = ε _wc + ΔCr (6)

FIG. 6 shows the plate width change rate ΔWrb / when rolled by a convex roll, a flat roll and a concave roll.
The relationship between W and the crown ratio change ΔCr is shown. This FIG. 6 includes data on different inlet side plate thicknesses, inlet and outlet side tensions, and rolling reductions, but ΔWrb / W = Δ in the region where ΔCr is negative.
The relationship of Cr (an example of the function f (ΔCr)) is substantially established. This means that the width change can be explained only by the deviation component, and the central component is almost zero, that is, the widthwise strain ε _wc at the central portion of the plate width is almost zero.

On the other hand, in the region where ΔCr is positive, the experimental point is slightly deviated from the relationship of the straight line (ΔWrb / W) = ΔCr. Therefore, the strip width change in rolling with an increased crown ratio cannot be explained only by the deviation component, and it is necessary to consider the central component. That is, it is shown that the width expansion due to the increase of the crown ratio is canceled by the width contraction of the central portion, and the width change becomes small as a whole.

FIG. 7 shows the inlet tension σ when ΔCr is positive.
The relationship between the ratio of _{b to} the deformation resistance σ _o and the ratio of the width change ratio to the crown ratio change is shown. From FIG. 7, the following (7) can be found between the entry side tension σ _b and (ΔWrb / W) / ΔCr.
It can be seen that the relationship of the expressions (an example of the function g (ΔCr, σ _b , σ _o )) holds.

(ΔWrb / W) / ΔCr = 1−α · σ _b / σ _o (7)

The deformation resistance σ _o is a stress that causes 0.1% strain at a strain rate of 0.01 (1 / s) in the aluminum material used in the experiment, and in this experiment, σ _o = 60 MPa. did. Needless to say, as σ _o , when applied to an actual machine, it is necessary to use the deformation resistance in the vicinity of the roll bite entry side of the material to be rolled. α is a constant that is determined based on experiments or operation results.

As described above, as the formula for changing the width near the roll bite,
The following equations (8A) and (8B) hold.

ΔWrb / W = ΔCr (ΔCr ≦ 0) (8A) ΔWrb / W = (1−α · σ _b / σ _o ) · ΔCr (ΔCr ≧ 0) ... (8B)

According to the study of the present inventors, the above (8A),
As shown in the equation (8B), it has been found that a change in plate width in the vicinity of the roll bite can be expressed regardless of the rolling reduction, the inlet / outlet tension, and the inlet plate thickness. Here, ΔC
Two polynomials were prepared and approximated according to the sign of r, but it goes without saying that an appropriate non-linear function may be used to approximate a continuous function regardless of the sign of ΔCr.

The results of a more detailed investigation of the above experiment will be described below.

FIG. 8 shows changes in the rolling direction of the plate crown in the convex roll rolling of (20 μm / radius). Here, the vertical axis x is the distance from the roll bite exit side, and the horizontal axis is
z is the width of the plate with the center in the width direction as the origin, and OP
Represents an operation side end, and DR represents a drive side end. As can be seen from FIG. 8, the plate crown changes in accordance with the change in width before the start of rolling, and the end portion is reduced in thickness as the roll bite approaches the roll bite and the plate crown increases. On the output side of the roll bite, the crown ratio of the plate is negative (concave crown) due to the influence of the convex roll.

In order to investigate the deformation behavior on the entry side of the roll bite in the convex roll rolling, the strain ε _{w in the} strip width direction and the strain ε _{l in the} rolling direction were measured with an orthogonal biaxial strain gauge, and the results were obtained. , FIG. 9 and FIG. 10, respectively. As shown in Figure 9, the rhombus is centered in the width direction (100m from the edge).
In m), the triangle represents the measured value at each position of the quarter part (50 mm from the end), the circle represents the widthwise end (5 mm from the end), and the black mark represents the DR side. 9 and 10
As can be seen from the above, the roll bite entry side extends in the rolling direction at the end portion in the plate width direction and contracts in the width direction. However, the pre-deformation on the roll bite entry side hardly occurs in the center part of the plate width and the quarter part.

The deformation on the entry side of the roll bite is such that the crown ratio is reduced, that is, the rolling is performed in a stretched manner,
It can be said that tensile stress is generated at the end on the roll bite entrance / exit side, and the width and thickness are shrunk on the entry side not subjected to work hardening by rolling.

Further, FIG. 11 shows changes in the rolling direction of the plate crown in the vicinity of the bite preventing portion (roll bite) in the concave roll rolling of (20 μm / radius). As can be seen from this figure, on the roll bite exit side, the plate thickness at the plate end is thinner than at the center, and the plate crown is increased. On the other hand, on the roll bite entry side, the thickness of the central portion decreases and the plate crown decreases as the roll bite approaches.

12 and 13 (the above 9 in the case of a convex roll,
(Corresponding to FIG. 10) shows the measurement results of the strain in the width direction and the strain in the rolling direction on the roll bite entry side in the case of the concave roll rolling. As can be seen from this figure, in the center part of the strip width, the roll bite entry side extends in the rolling direction and contracts in the strip width direction. Almost no pre-deformation occurred at the plate width edge. The deformation on the roll bite entry side is large in the rolling reduction at the edges, so metal is insufficient in the rolling direction at the center part, and tensile stress is generated at the center part of the strip width on the roll bite entry side and stretches in the rolling direction, resulting in , It is thought that the width has shrunk.

Conventionally, it is considered that the central portion of the plate width does not deform even when the crown ratio increases, and the formula (8A) has been used regardless of whether the crown ratio change ΔCr is positive or negative. From the detailed study this time, it became clear that the influence of the change of the crown ratio on the change of the plate width greatly depends on the positive or negative of ΔCr, and when ΔCr is positive, the formula (8B) should be used.

The experiment carried out for this detailed examination is for the case of the plate width / plate thickness ratio: W / H = 100 or 200,
This corresponds to the middle and later stages of the finishing mill group of the actual machine, but in this case, as shown in the formulas (8A) and (8B), the width change can be expressed only by the crown ratio change and the entry side tension. It has become clear that the effect of so-called simple widening within can be ignored.

Therefore, the strip width control means such as the edger rolling mill and the tension AWC are also installed on the entry side of the middle stage stand (for example, the third stand), and the strip width control means is predicted by predicting the strip width change in the downstream side stand. When controlling the operation amount of, the equations (8A) and (8B) may be used as they are.

However, in the front stand of the finish rolling mill having a plate thickness larger than the plate width, the effect of so-called simple width expansion in the roll bite cannot be ignored.

Therefore, the influence of this simple width expansion was investigated based on the actual machine operation data. The problem here is that the width change accompanying the so-called crown ratio change,
This means that it is impossible to strictly separate the width change, which is so-called a simple width expansion in the roll bite or a rectangular cross-sectional width expansion. Therefore, the simple width expansion in the roll bite is calculated from the width change amount in the actual machine to the width change amount due to the inter-stand tension described below and (8A),
It was determined as a value obtained by subtracting the roll bite neighborhood width change amount calculated from the equation (8B). FIG. 14 shows the distribution of the simple width spread ΔWs in each stand thus obtained. As shown in this figure, it is understood that the simple width spread ΔWs is concentrated in the front stand as in the conventional experiment.

Further, from the above formula (4), the width change amount due to the widthwise strain ε _{wc at the} center portion of the plate width in the deformation near the roll bite is ΔW1 = W · ε _wc, and the widthwise central portion of the widthwise strain is Assuming that the amount of width change corresponding to a value obtained by integrating the deviation Δε _w from −W / 2 to + W / 2 is ΔW2, the width change ΔWrb near the roll bite can be expressed by the following equation (4 ′). Therefore, in the case of ΔW1 in this equation, the influence of the simple width spread ΔWs appears in the preceding stage of the finishing rolling mill group.

ΔWrb = ΔW1 + ΔW2 (4 ')

On the other hand, the following equation (6 ') is obtained from the equation (6).

ΔWrb = W · ε _wc + W · ΔCr = ΔW1 + W · ΔCr (6 ')

From the above equations (4 ') and (6'), the following equation (9) is obtained.

ΔW2 = W.ΔCr (9)

From the above equations (8A) and (8B), when the simple width spread ΔWs cannot be ignored, the following (10)
Equations A) and (10B) are obtained.

[0052] ΔWrb = W · ΔCr + ΔWs ( ΔCr ≦ 0) ... (10A) ΔWrb = (1-α · σ b / σ o) · W · ΔCr + ΔWs (ΔCr ≧ 0) ... (10B)

Substituting the equation (9) into the equations (10A) and (10B), the following (10A ') and (10B')
It becomes an expression.

[0054] ΔWrb = ΔW2 + ΔWs (ΔCr ≦ 0) ... (10A ') ΔWrb = -α · (σ b / σ o) · W · ΔCr + ΔW2 + ΔWs (ΔCr ≧ 0) ... (10B')

Comparing the equations (10A ') and (10B') with the equation (4 '), the following relationship is obtained.

ΔW1 = ΔWs (ΔCr ≦ 0) (11A) ΔW1 = −α · (σ _b / σ _o ) · W · ΔCr + ΔWs (ΔCr ≧ 0) (11B)

Various empirical formulas for the simple width expansion in the roll bite have been proposed in the past. The inlet side tension σ _b , the inlet side plate thickness H, the rolling reduction γ, the work roll diameter R, the plate width W. , Can be expressed as a function of the coefficient of friction μ between the roll and the plate. Therefore, the above (11A), (11B)
The width change amount ΔW1 due to the widthwise strain ε _wc of the central portion of the plate width in the deformation near the roll bite represented by can be expressed by the following functional form.

ΔW1 = ΔWs (σ _b , H, γ, R, W, μ) (ΔCr ≦ 0) (11A) ΔW1 = −α · (σ _b / σ _o ) · W · ΔCr + ΔWs (σ _b , H, γ, R, W, μ) (ΔCr ≧ 0) (11B)

Further, the plate width change amount ΔW due to the deviation Δε _w from the plate width center portion in the width direction strain in the vicinity of deformation of the roll bite.
2 can be expressed as in the equation (9).

In particular, when rolling under conditions in which the shape change cannot be ignored, the following equation using the shape change coefficient ξ may be used.

ΔW2 = (1-ξ) · W · ΔCr (12)

In this examination, the first approximation is
In the above formula (11B), ΔW1−ΔWs can be expressed only by the crown ratio change, the entry side tension and the deformation resistance. However, when applied to the actual machine operation, various other parameters are in the form of polynomials as is usually done. It is desirable to use the multiple regression equation added in. At this time, it is effective for the actual machine operation in which the disturbance cannot be avoided by preparing a coefficient for each steel type and further appropriately correcting it by online learning. What is particularly important as the knowledge on which the present invention is based is that the shape of deformation near the roll bite changes depending on whether the crown ratio change is positive or negative. It should be in the form of an equation that can take into consideration the difference in the deformation form due to the positive or negative of the change.

Next, the width shrinkage amount ΔW due to the tension between the stands
3 will be explained. However, ΔW3 is positive when the width is reduced.

First, a low strain rate hot tensile test conducted for the purpose of evaluating the width shrinkage between stands due to creep deformation will be described. The test piece has a rectangular cross section of 10 mm × 5 mm, and the gauge length is 50 mm. The test conditions are as follows. Material: 0.05% carbon steel, 0.03% carbon steel Test temperature T0: 900, 950, 1000, 1050 ° C Strain rate: 10 ^-4 to 10 ^-2 (s ^-1 ).

In this test, as shown in FIG. 15 (A), first, the temperature was kept at 1050 ° C. for 15 minutes to make the crystal grain size uniform, and then the test temperature was kept at the target test temperature for 10 minutes to conduct a tensile test at a constant speed. went.

An example of the test result is shown in FIG. This figure shows the work-hardening type stress-strain relationship. It can be seen that the higher the temperature, the lower the strain rate, and the higher the carbon concentration, the smaller the deformation resistance. The curve shown in FIG. 15 (B) is the regression result by the following equation (13).

[0067]

[Equation 4]

In the actual behavior of width reduction between stands, since the effects of work hardening by rolling in the preceding stand, recovery between stands, and recrystallization cannot be ignored, the residual rate λ is used in the width reduction prediction equation between stands. Need to consider. As is well known, the residual rate λ is the temperature T and the stay time between stands Δt.
, A function such as residual strain on the exit side of the immediately preceding stand. Further, when pulled in the rolling direction, the strains in the width direction and the thickness direction may be generated in substantially the same amount.

In FIG. 16, the tension between the first and second stands F1 and F2 and between the fifth and sixth stands F5 and F6 in the actual machine is set to 0.5 kgf / mm ^{2 at} which the creep deformation can be ignored and the predetermined tension is applied. The actual measurement value of the plate width change amount that occurs when the value is changed stepwise up to and the calculation value (solid line) by the prediction formula of the above formula (13) are shown.

The calculated value of the width shrinkage amount ΔW3 due to the tension between the stands based on the equation (13) was obtained using the following equation (16) derived as follows.

First, the equation (13) is modified to obtain the following equation (14).

[0072]

(Equation 5)

From the above, the width shrinkage amount ΔW3 due to the tension between the stands can be expressed as a function represented by the following equation (17).

[0074]

(Equation 6)

In the prediction calculation by the computer, it is general to use a method of summing the variation amounts for every minute time. In this case, it goes without saying that each parameter should be a function of the position between stands. . Further, when a shape change (ear wave, abdominal wave) occurs, tension is concentrated (stress concentration) on a portion that is not a wave, so that the width reduction between stands is accelerated until the shape becomes flat. When rolling such that the shape is disturbed, the above effect is considered.

In the above description, Wrb (= ΔW
1 + ΔW2) is the amount of width change required for each stand, and ΔW3 is the amount of width change required for each stand. Therefore, for example, the plate width change amount Δ from the Kth stand to the Lth stand
When predicting W, the following formula (18) or (19)
Expressions may be used. However, here, the space between the i-th stand and the (i + 1) th stand is defined as the space between the i-th stands. Further, the expressions (18) and (19) are plate width change prediction expressions applied when the plate width control means on the K-th stand entry side is used.

[0077]

(Equation 7)

It should be noted that ΔW1 and ΔW2 in the above equation (19)
Is given by the equations (11A), (11B) and (9) derived using the equations (8A) and (8B).

As described in detail above, according to the present invention, with respect to the stand on the downstream side of the middle stage of the finishing rolling mill group in which the influence of the simple width expansion can be ignored, the ΔWrb in the above equation (18) is added to the above (8A), By applying the expression (8B) as it is, and applying the expression (19) to the upstream side stand that cannot be ignored, the difference in the plate width change behavior due to the positive or negative of the crown ratio change in each stand is taken into consideration. It is possible to perform highly accurate strip width control using the width change prediction formula.

However, as a guideline, the simple width spread can be ignored for a stand having a delivery side plate thickness of 10 mm or less, but it varies depending on the coefficient of friction between the roll and the material, the roll diameter, and the required accuracy. Since it is not possible to clearly distinguish between the expression (18A) and the expression (8B) applied to the expression (18) and the expression (19), an appropriate expression is used by trial and error.

[0081]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows rolling equipment applied to one embodiment according to the present invention. This equipment is provided with the fourth and fifth stands R4 and R5 constituting the rough rolling mill and the downstream side thereof. And a finishing mill group consisting of first to seventh stands F1 to F7, and edger rolling mills (sheet width control means) E4, E5 and E6 arranged on the respective inlet sides of the stands R4, R5 and F1. In addition, each stand F1 of the finishing rolling mill group
F7 is controlled by the finish rolling mill control device 10, the rough rolling mill group is controlled by the rough rolling mill control device (not shown), and each of the edger rolling mills E4 to E6 is controlled by the edger control device 12. ing. Further, in the finish rolling mill control device 10, the edger control device 12, etc., from the arithmetic device 14, to each stand or edger rolling mill for which setup calculation is performed based on target values such as material characteristics and product dimensions, rolling conditions and the like. The operation amount and the like are input.

Further, in the above rolling equipment, the sensor assembly including the width gauge, the thermometer, the crown gauge (thickness gauge), and the shape detector (height gauge) indicated by reference numeral 16 in the drawing is inserted into each stand. Side and the exit side of the seventh stand F7, various sensor information obtained by detecting the material S to be rolled by each of these sensor assemblies 16 is input to the arithmetic unit 14 and these information are stored here. The setup calculation and the control calculation are performed by using this.

Next, the seven stands F1 to
By predicting the amount of width change that will occur in the finishing rolling mill group consisting of F7, and operating the edger rolling mill E5 based on the predicted value, the target strip width on the finishing rolling mill group feeding side (the feeding side of the final stand F7) An example of the case of matching

The width change prediction formula used is the above formula (19), and the plate width change amount (ΔW) i for each stand is given by
0) and multiple regression using operating data is performed for each stand i to set the respective coefficients a _i , b _i , c _i of ΔW1, ΔW2, and ΔW3, and obtain (ΔW )
The sum of i is defined as equation (19).

(ΔW) i = a _i (ΔW1) _i + b _i (ΔW2) _i + c _i (ΔW3) _i (20)

In this equation, the coefficients a _i , b _i , and c _i are appropriately classified according to the rolling conditions of each stand, for example, the strip thickness, strip width, rolling reduction, rolling temperature, steel grade, etc. A table method in which a value is determined for each category may be used. Alternatively,
You may express by the polynomial which makes the above-mentioned item a variable. The reason for doing this is that if the rolling conditions represented by the above items change, the respective coefficients a _i , b _i , and c _i also change.

Here, the edger rolling machine (plate width control means)
The predicted values were used as the plate crowns after being processed by and the ratio of the plate crowns on the stand-out side of each stand. In the case of a plate crown, the plate crown after the next horizontal rolling is predicted in consideration of so-called dock bone deformation caused by the edger rolling. The exit crown of each stand is based on material conditions (entrance plate crown (distribution of plate thickness in the plate width direction), deformation resistance, etc.) and rolling mill conditions (roll diameter, roll rigidity, rolling mill rigidity, initial roll Crown, wear amount, heat up amount, roll shift amount, bender pressure, roll cloth amount, etc.)
Is calculated by using a method such as FEM (finite element method) or division model. The target value was used as the crown ratio on the feeding side of the finishing rolling mill.

The operation amount of the edger rolling mill at each position in the rolling direction can be determined by the edger rolling mill E5, for example, by the following procedure. Predicted strip width W _out (= strip width W _in + strip width change amount Δ
A target width on the exit side of the fifth stand R5 of the rough rolling mill corresponding to W _in is obtained so that W) matches the target strip width W _p on the exit side of the finish rolling mill. In this calculation, the target strip width, strip thickness, crown, temperature of the finishing rolling mill group side, steel type of the material to be rolled, characteristics such as temperature, and the rolling conditions of the finishing rolling mill calculated based on these are Used. Here, the rolling conditions of the finish rolling mill are roll gap, bender pressure, roll peripheral speed, roll shift amount, roll cross amount, inter-stand tension, etc. at each stand.

In order to realize the target strip width of the entry strip width W _in of the finishing rolling mill group, prediction calculation of strip width after passing through the fifth stand R5, strip crown and the like is performed with respect to the manipulated variable of the edger rolling mill E5. , Determine the operation amount of the edger rolling mill E5. At this time, needless to say, the width return amount of the horizontal reduction ratio due to the dockbone shape generated by the width reduction is considered. At that time, the edger rolling mill E5 may be subjected to feedback control based on the measured value of the entry side strip width W _in of the finishing rolling mill group.

In order to perform the above series of calculations with high accuracy, it is necessary to repeat the calculations until the variation of each parameter is sufficiently converged. Furthermore, the strip width change prediction calculation formula of the above formula (19) is corrected based on information from various sensors installed on the inlet side / outlet side of the finishing rolling mill group and / or inside the finishing rolling mill group. May be. Further, feedback control of the opening degree of the edger rolling mill on the entry side of the finishing rolling mill group based on the information of the strip width gauge on the exit side of the final stand F7 may be combined with the stationary portion.

As a method of applying this embodiment to the actual operation, the delivery side target strip width of the finishing rolling mill group is 1 to 10 times larger than the product width.
There is a method in which the width is adjusted to be about 10 mm wider and the width is dynamically adjusted by a width control means (edger rolling mill) using tension between stands in the finishing rolling mill group.

Although omitted in the above description as a matter of course, it goes without saying that the effect of thermal expansion is corrected.

When the control of the edger rolling mill E5 shown in FIG. 1 is carried out by applying the method of this embodiment and the conventional method, the relationship between the target value and the actually measured value of the finishing mill group feeding side width is shown as follows. These are shown in FIGS. 2 and 3, respectively. Here, with the conventional method, the width change prediction is performed using the width change prediction formula that the crown ratio change and the width change have a linear relationship, and the opening pattern of the edger rolling mill is set based on the predicted value. Is the way.

From the comparison between FIG. 2 and FIG. 3, it is understood that by performing the control according to the present invention, the error of the width control is reduced and the precision of the plate width control can be greatly improved.

The present invention has been specifically described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, in the above-mentioned embodiment, the case where the edger rolling machine is used as the strip width control means is shown, but the strip width control means is not limited to this, and various width control means such as a width press and a tension control may be used. it can.

[0098]

As described above, according to the present invention,
By using the plate width change prediction formula that takes into account the difference in the plate width change behavior depending on the positive or negative of the crown ratio change in each stand, the plate width prediction accuracy and the product width accuracy are improved compared to the past, and the yield is improved. It is possible to obtain an excellent effect that the above can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of rolling equipment applied to one embodiment according to the present invention.

FIG. 2 is a diagram showing a relationship between an actually measured value and a predicted value of a strip width change amount when the control method of the present invention is applied.

FIG. 3 is a diagram showing a relationship between an actually measured value and a predicted value of a strip width change amount when the conventional control method is applied.

FIG. 4 is a diagram for explaining a crown ratio Cr.

FIG. 5 is a diagram for explaining the widthwise strain ε _w .

FIG. 6 is a diagram showing a relationship between a change in crown ratio and a change in width.

FIG. 7 is a diagram showing the relationship between the entrance tension in a region where the crown ratio change is positive and the width change rate with respect to the crown ratio change.

FIG. 8 is a diagram showing a change in the rolling direction of the plate crown in a region where the change in the crown ratio is negative.

FIG. 9 is a diagram showing a change in width-direction strain on the roll bite entry side in a region where the change in the crown ratio is negative.

FIG. 10 is a diagram showing a change in strain in the rolling direction on the roll bite entry side in a region where the change in the crown ratio is negative.

FIG. 11 is a diagram showing a change in the rolling direction of the plate crown in a region where the change in the crown ratio is positive.

FIG. 12 is a diagram showing a change in strain in the width direction at the roll bite entrance in a region where the change in the crown ratio is positive.

FIG. 13 is a diagram showing a change in strain in the rolling direction at the roll bite entrance in a region where the change in the crown ratio is positive.

FIG. 14 is a diagram showing a simple width expansion amount in each finishing stand.

FIG. 15 is a diagram showing a method of hot tensile test and its result.

FIG. 16 is a diagram showing the results of a tension change experiment between the first and second stands and between the fifth and sixth stands of the finish rolling mill group.

FIG. 17 is a schematic diagram showing strip width change behavior in the finishing rolling mill group.

[Explanation of symbols]

 10 ... Finishing rolling mill control device 12 ... Edger control device 14 ... Computing device 16 ... Sensor assembly R4, R5 ... Rough rolling stand F1 to F7 ... Finishing rolling stand E4 to E6 ... Edger rolling mill

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Kitahama 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture No. 1 Kawasaki-cho, Kawasaki Steel Co., Ltd. (72) Inventor Yoshinori Iwasaki Mizushima Kawasaki Dori, Kurashiki City, Okayama Prefecture (72) Inventor Kawasaki Steel Co., Ltd. Steel Development & Production Division Mizushima Steel Works

Claims (4)

[Claims] 1. A rough rolling mill and / or finish rolling based on the calculated value and a target strip width on the delivery side of the finishing rolling mill group, by predicting the strip width variation amount in the finishing rolling mill group. In the strip width control method in hot rolling in which the operation amount of strip width control means provided in the vicinity of the rolling mill group is controlled, in each rolling stand, the crown ratio Cr _out on the exit side is used.
The crown ratio change ΔCr obtained by subtracting the crown ratio Cr _in on the input side is calculated from _{W = g (ΔCr, σ b} , σ o) (ΔWrb: sheet width change in the vicinity of the roll bite, W: strip width, sigma
_b : Entry-side tension, σ _o : Deformation resistance) A strip width change expression in the vicinity of a roll bite is applied to predict and compute the strip width change amount. 2. The method according to claim 1, wherein the plate width change expression in the vicinity of the roll bite is ΔWrb / W = ΔCr when ΔCr ≦ 0, and ΔWrb / W = (1-α · σ when ΔCr ≧ 0. _b / σ _o ) ΔCr (α: constant), which is a strip width control method in hot rolling. 3. The predicted value of the plate crown after being processed by the plate width control means, the target crown of the finishing rolling mill group feeding side, and each stand feeding side plate in calculating the crown ratio change according to claim 1. A strip width control method in hot rolling, characterized by using an estimated value or a set value of a crown. 4. The strip width control method in hot rolling according to claim 1, wherein the strip width control means is an edger rolling mill.