JPS6358644B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the width of a rolled material such as a slab in a hot rough rolling mill group consisting of a plurality of vertical rolling mills and a plurality of horizontal rolling mills arranged alternately. It is.

In general, materials to be rolled such as slabs usually have variations in width and thickness at various parts in the longitudinal direction, and temperature differences are formed when heated in a heating furnace. The cross-sectional shape of the material is different, and due to roll opening setting errors and other control errors in each horizontal rolling mill and vertical rolling mill, the rolled material rolled in the rough rolling mill group has a larger width dimension. This causes variations and significantly reduces yield. For example, temperature differences are one of the major factors that cause variations in width dimensions of rolled materials.
The temperature of the part of the rolled material that is in contact with the skid (hereinafter referred to as the skid part) is lower than that of the part that is not in contact with the skid (hereinafter referred to as the non-skid part) due to the heat shielding effect of the skid. , since the temperature distribution in the width direction is also different in the non-skidded part, this occurs in both the longitudinal and width directions of the rolled material, and as a result, the cross-sectional shape of the rolled material after vertical rolling differs from that in the skidded part. This differs depending on the skid portion, and during repeated vertical rolling and horizontal rolling, the skid portion is rolled to a wide strip, while the non-skid portion is rolled to a narrow strip. For this reason, in the past, the following strip width control was performed using one appropriate vertical rolling mill in a group of rough rolling mills.

FIG. 6 is a schematic diagram showing a hot rough rolling mill group and its strip width control system, in which E ₁ , E ₂ , E ₃ . . . E ₆ are vertical rolling mills, R ₁ , R ₂ , R ₃ . . . R ₆ is a horizontal rolling mill, and the material to be rolled 1 is rolled alternately in the width direction and thickness direction from the direction of the white arrow in each vertical rolling mill E ₁ , etc. and horizontal rolling mill R ₁ , etc. It is designed to be rolled to the target width and thickness dimensions. As shown in Figure 6, the vertical rolling mill and the horizontal rolling mill downstream of it are usually placed close together, but the distance between the horizontal rolling mill and the vertical rolling mill downstream of it is the length of the material to be rolled. It's longer than that. Conventionally, the width gauge 2 is arranged in the middle of the hot rough rolling mill group, for example, on the exit side of the horizontal rolling mill _R3 , and the tip of the rolled material 1 is located downstream of the width gauge 2 in the vertical rolling mill. Before reaching E ₄ , the width gauge 2 measures the width of the strip at each longitudinal direction of the material to be rolled, and inputs this to the calculation control section 3 as the actual measured width of the material to be rolled. At the same time, the average width and the width deviation of each part in the longitudinal direction of the rolled material 1 from the measured width are determined based on the measured width, and the width deviation and average width of the rough rolling mill exit side are predicted based on the rolling schedule. In order for the predicted width deviation to be zero and the predicted average width to match the target width on the exit side of the rough rolling mill group, the width reduction amount (the difference between the strip width on the entrance side of the vertical rolling mill and the strip width on the exit side of the vertical rolling mill) is calculated. A command signal was sent from the arithmetic control unit 3 to the vertical rolling mill E ₄ disposed downstream of the horizontal rolling mill R ₃ to adjust its roll opening in order to obtain the width reduction amount.

However, in actual machine operation, variations in the width dimensions of the rolled material become extremely large due to variations in slab dimensions, material quality, rolling temperature, etc., or rolling conditions of vertical rolling mills and horizontal rolling mills upstream of the width gauge. For this reason, the actual width measured by the width gauge 2 and the target width at the exit side of the horizontal rolling mill R ₃ immediately before it are significantly different. For example, if the average width based on the actual width exceeds the target width by a large amount, The amount of width reduction required to correct this becomes extremely large in some parts, causing vertical rolling mill _E4 to be overloaded, and conversely, if the average width is less than the target width, substantial width reduction cannot be achieved. There were inconveniences such as the inability to control the width of the head.

Figure 7A shows the case where the average width of the rolled material 1 at the exit side of the horizontal rolling mill _R3 , that is, the input side of the vertical rolling mill _E4 , is significantly greater than the target width, and Figure 7B shows the case where the rolled material 1 3 is a graph showing cases in which the average width of is less than the target width, together with the roll opening degree of vertical rolling mill _E4 set in each case. In both FIGS. 7A and 7B, the horizontal axis represents the position in the longitudinal direction of the material to be rolled, and the vertical axis represents the width of the material to be rolled or the opening degree of the rolls. The solid line a in the graph shows the measured width in the longitudinal direction of the rolled material, the broken line b shows the average width of the rolled material, the broken line c shows the target width at the exit side of the horizontal rolling mill _R3 , and the solid line d shows the vertical width. The actual roll opening degree of rolling mill E ₄ is
The broken line e shows the average roll opening, and the broken line f shows the roll target opening.

As is clear from Fig. 7A, when the average width b of the rolled material significantly exceeds the target width c, the difference between the average width b and the measured width a, that is, the width deviation, is reduced to zero on the rough rolling mill group exit side. In order to make the average width b coincide with the target width c on the rough rolling mill group outlet side, the rolling rolls of the vertical rolling mill E ₄ have a wide part (average It is necessary to increase or decrease the amount of width reduction depending on the area (where the actual width a is wider than the average width b) and the narrow area (the area where the actual width a is narrower than the average width b). In the portions _d1 , _{d2 , .}

On the other hand, as is clear from FIG. 7B, when the average width b of the rolled material 1 is less than the target width c, the vertical rolling machine is used to eliminate the difference between the average width b and the measured width a, that is, the width deviation. For the _E4 rolling roll, it is necessary to increase or decrease the amount of width reduction depending on the wide and narrow parts of the material to be rolled, as shown by the actual roll opening d. The actual roll opening degree d in the portions d ₁ ′, d ₂ ′…d ₄ ′ where the amount of killing should be reduced
is larger than the width dimension of the material to be rolled 1, and width reduction cannot be performed, making it virtually impossible to control the strip width.

The present invention was made in view of the above circumstances, and its purpose is to actually measure the plate width of the material to be rolled at the middle of the rough rolling mill group, and to calculate the average width and the width relative to the average width from this measured width. Along with finding the deviation,
The width deviation and average width at the exit side of the rough rolling mill group are predicted, and the actual roll opening degree is controlled to zero the width deviation of the rolled material at the exit side of the rough rolling mill group, respectively. When the average width of the rolled material significantly exceeds the target width by controlling the actual opening of the rolls to match the predicted average width of the rolled material to the target width using separate vertical rolling mills, or Even if the average width is less than the target width, the vertical rolling mill will not be overloaded, and problems such as the inability to control the width of the rolled material will be eliminated, and variations in rolling accuracy due to the rolling conditions of the horizontal rolling mill will be eliminated. The object of the present invention is to propose a strip width control method that solves this problem and makes it possible to obtain a strip material that matches the target width on the exit side of the rough rolling mill group.

The strip width control method according to the present invention is applied to a hot roughing mill group configured by alternately arranging a plurality of vertical rolling mills and a plurality of horizontal rolling mills, on the output side of the horizontal rolling mill in the middle of the roughing mill group. Measure the plate width of each part in the longitudinal direction of the rolled material using a width meter placed at In addition to determining the width deviation from the measured average width, the predicted average width at the rough rolling mill group exit side predicted based on the measured average width is determined, and the predicted average width at the rough rolling mill group exit side predicted based on the width deviation is calculated. In order to make the width deviation from the predicted average width zero, the roll opening degree is controlled during rolling of the material to be rolled in the vertical rolling mill A located downstream of the width gauge, and the roll opening degree is also controlled. Vertical rolling mill B downstream of vertical rolling mill A performs vertical rolling before the tip of the material to be rolled reaches vertical rolling mill B so that the predicted average width at the exit side of the rough rolling mill group is approximately equal to the target width. The feature is that the roll opening setting value of machine B is corrected.

The present invention will be described below in a hot rough rolling mill group consisting of six vertical rolling mills E ₁ to _{E 6} and horizontal rolling mills R ₁ to _{R 6} arranged alternately as shown in the schematic diagram of FIG. A case will be described in which the width of a rolled material is controlled.

The material to be rolled 1 is transferred in the direction of the outlined arrow and is transferred to each of the vertical rolling mills E ₁ to E ₆ and horizontal rolling mills R ₁ to _{R 6} .
The width is adjusted while passing through the vertical rolling mills E ₁ to _{E 6} and horizontal rolling mills.
R ₁ to _{R 6} are arranged alternately, and the width is adjusted for each set of vertical rolling mills and horizontal rolling mills.

Reference numeral 2 denotes a width gauge disposed on the exit side of the horizontal rolling mill R ₃ , which continuously measures the width dimension of the rolled material 1 after rolling by the horizontal rolling mill R ₃ over the entire length of the rolled material 1. Alternatively, the actual measurement data is taken intermittently into the computer 3 at an appropriate sampling interval, and this is stored as the actual measurement width _w3 of the rolled material 1 at the exit side of the horizontal rolling mill _R3 . The actually measured average width ( _hereinafter simply referred to as average width) w _3A of the rolled material 1 is calculated based on the width w 3, and the rolled material 1 is calculated from the average width w _3A and the measured width w ₃ .
The difference between the two at each longitudinal direction, that is, the width deviation Δd, is calculated, and in order to eliminate this width deviation Δd, the roll opening of vertical rolling mill E ₄ is set and controlled, and the final horizontal rolling mill R ₆ is Vertical rolling mill E 5 downstream of vertical rolling mill E ₄ where control is performed to eliminate the width deviation Δd in order to match the predicted average width w _6A with the target width W ₆ ^ at the exit side of the rough rolling mill _group . The roll opening degree is corrected and controlled. The control of the roll opening degree for the vertical rolling mill _E4 will be explained below. First, the relationship between width reduction by the vertical rolling mill and width expansion by the horizontal rolling mill will be explained based on Figure 2 A, B, and C. Figure 2 A is a vertical cross-sectional view in the plate width direction of the rolled material before vertical rolling, Figure 2 B is the same cross-sectional view after vertical rolling (before horizontal rolling), and Figure 2 C is after horizontal rolling. FIG.

Let the plate width and plate thickness of the rolled material 1a before vertical rolling, the rolled material 1b after vertical rolling, and the rolled material 1c after horizontal rolling be W, H, W _E , H _E and w, h, respectively. The width reduction amount ΔW (ΔW/2 on one side) by the vertical rolling mill is expressed as ΔW=W-W _E , and by performing the width reduction, the width direction end portions are raised.
The amount by which this raised portion M _E appearing on the rolled material 1b widens in the next horizontal rolling is w _M (w _M / on one side).
2), The amount by which the middle rectangular cross section excluding the raised part M _E widens by horizontal rolling is w _H (on one side)
w _H /2), the strip width w after horizontal rolling is expressed as w=W _E +w _M +w _H (1). However, the width expansion amount w _M and w _H
is expressed as the following equations (2) and (3) using the condition that the volume is constant before and after vertical and horizontal rolling.

w _M = γ・ΔW …(2) w _H ≒ {(H/h)C ^H −1}W _E …(3) However, γ: Embankment width expansion coefficient C _H : Only generally used horizontal rolling However, according to the results of an actual machine test on a group of rough rolling mills, the present inventors found that γ and C _H can be expressed by the following equations (4) and (5).

γ=0.22(W/H) ^0.18・(W/ΔW) ^0.19 …(4)
C _H =2.05exp{−1.766(W _E /ld) ^0.1・(W _E /H) ^0
.435・(H/R) ^0.09 }...(5) However, ld: Projected contact arc length during horizontal rolling R: Roll radius of horizontal rolling mill In other words, from equations (1) and (2) above, horizontal rolling mill Even without directly adjusting the width of the material to be rolled, the width of the material to be rolled can be adjusted by adjusting the width reduction amount ΔW, in other words, the roll opening degree of the vertical rolling mill.

Therefore, rolled material 1 captured on the output side of horizontal rolling mill _R3
Predict the width deviation at the exit side of the rough rolling mill group from the width deviation Δd of each part in the longitudinal direction and the bulge width expansion coefficient γ for each set of vertical rolling mill and horizontal rolling mill, and eliminate this width deviation, In other words, the vertical rolling mill E ₄
In this step, the roll opening degree is controlled so that the width reduction amount for the wide portion is larger than the width reduction amount for the narrow width portion by a required amount.

Now, for example, horizontal rolling mill Ri _-1 on the i-1 side from the entry side of the rough rolling mill group, the i-th vertical rolling mill Ei placed downstream of it, and the horizontal rolling mill Ei placed close to the downstream side of the vertical rolling mill Ei. The relationship between the width deviation from the average width of the longitudinal dimension of the rolled material at each exit side of the i-th horizontal rolling mill Ri is determined.

Now, on the exit side of the horizontal rolling mill Ri _-1 on the i-1 side, a part where a width deviation of ΔD _Ri-1 occurs (hereinafter referred to as the variable part) and a part where the width deviation is zero (hereinafter referred to as the non-variable part) Focus on Here, the width deviation of the fluctuating part ΔD _Ri-1
If it is a positive value, it corresponds to a wide width part, and if it is a negative value, it corresponds to a narrow width part. i-1 horizontal rolling mill
If the average width in the longitudinal direction of the rolled material on the exit side of Ri _-1 (that is, the strip width of the non-fluctuation part) is Wi _-1 , then the strip width of the fluctuating part is expressed as Wi _-1 +ΔD _Ri-1 .

Next, when roll opening control is not performed in the i-th vertical rolling mill Ei, that is, when rolling is performed with a constant roll opening setting value from the front end to the rear end of the rolled material, the rolled material on the exit side of vertical rolling mill Ei If the average width in the longitudinal direction of the material (i.e. the plate width of the non-variable part) is W _Ei , and the width deviation of the variable part is ΔD _Ei as before, then the plate width of the variable part is
It is expressed as W _Ei +ΔD _Ei . Therefore, the width reduction amount of the variable part (difference between the width of the inlet plate and the width of the outlet plate of the vertical rolling mill)
ΔW _Wi is given as shown below.

W _Wi = Wi _-1 + ΔD _Ri-1 − (W _Ei + ΔD _Ei ) Here, the width reduction amount ΔW _Ei of the non-fluctuation part is expressed as ΔW _Ei = Wi _-1 − W _Ei , so the width reduction amount of the fluctuation part is If we rewrite the equation for ΔW _Wi using the width reduction amount ΔW _Ei of the non-variable part,
It becomes as shown in equation (6).

ΔW _Wi = ΔW _Ei + ΔD _Ri-1 −ΔD _Ei (6) Equation (6) shows that when the roll opening is not controlled in the vertical rolling mill Ei, if there is a width deviation on the entrance side of the vertical rolling mill Ei, This shows that the width reduction amount changes depending on the part, and as shown in equation (2), if the width reduction amount changes, the amount of bulge width expansion changes, and the horizontal rolling mill Ri
The width deviation at the exit side can be determined. Now, if the bulge width expansion coefficient of the fluctuating part is γw, the bulge width expansion amount wMWi of the fluctuating part on the exit side of the horizontal rolling mill Ri can be expressed as shown in equation (7) from equation (2).

wMWi=γw・(ΔW _Ei +ΔD _Ri-1 −ΔD _Ei ) …(7) Also, if the bulge width expansion coefficient of the non-fluctuation part is γ, then the bulge width expansion of the non-fluctuation part on the exit side of the horizontal rolling mill Ri The quantity w _Mi can be expressed as in equation (7') from equation (2).

w _Mi = γ・ΔW _Ei …(7′) In addition to the amount of width expansion caused by the horizontal rolling mill, the normal width expansion amount shown by equation (3) is also taken into account, in addition to the amount caused by the bulge mentioned above. However, as is well known, the amount of normal width expansion is determined by the sheet width, sheet thickness, roll diameter, and reduction amount, so it is thought that it will be approximately equal in the fluctuating section and the non-fluctuation section. Therefore, it does not appear as a width deviation.

Therefore, the width deviation ΔD _Ri of the fluctuating section on the exit side of the horizontal rolling mill Ri is ΔD _Ri = wMWi + ΔD, -w _Mi. Using equations (7) and (7'), the above equation becomes ΔD _Ri = γw・(ΔW _Ei +ΔD _Ri-1 −ΔD _Ei ) +ΔD _Ei −γ・ΔW _Ei …(8) However, if roll opening control is not performed, the width deviation at the exit side of the vertical rolling mill is usually extremely small, and ΔD _Ri ≫ Since ΔD _Ei , ΔD _Ri-1 ≫ΔD _Ei , the width deviation ΔD _Ri in the above equation (8) can be expressed as in the following equation (9).

ΔD _Ri = γw・(ΔW _Ei +ΔD _Ri-1 )−γ・ΔW _Ei =(γw−γ)・ΔW _Ei +γw・ΔD _Ri-1 …(9) Next, a specific rolling mill of the rough rolling mill group, i.e. In the m-th vertical rolling mill from the entry side (the fourth vertical rolling mill E ₄ in the example), strip width control is performed to eliminate strip width fluctuations on the exit side of the roughing mill group by adjusting the roll opening degree. Let's take a look. This strip width control is performed so that the strip width variation on the exit side of the rough rolling mill group is zero, and of course, when rolling the fluctuating section, non-standard control is performed to compensate for the width deviation caused by subsequent rolling. It is necessary to correct the plate width compared to the variable part. Here, if the variable part corresponds to a wide part, the plate width is narrowed compared to the non-variable part, and if the variable part corresponds to a narrow part, the plate width is made wider compared to the non-variable part. need to be corrected. Therefore, let this value, that is, the value for correcting the plate width of the variable part with respect to the plate width of the non-variable part, be Δwm. On the other hand, for the width deviation ΔD _Rn on the exit side of the m-th horizontal rolling mill, in the general formula (8), ΔW _Ei is replaced by ΔW _En , and ΔD _Ri-1 is replaced by ΔD _Rn-1 . Furthermore, ΔD _Ei , which is the width deviation on the exit side of the i-th vertical rolling mill, is determined by adjusting the roll opening degree in the m-th vertical rolling mill as described above, so that the strip width in the variable section is wider than the strip width in the non-variable section. Since the correction control is performed by Δwm, this width deviation is replaced by −Δwm, which is the sign of Δwm reversed.

Therefore, equation (8) can be expressed as ΔD _Rn = (γw−γ)・ΔW _En +γw・ΔD _Rn−1 −(1−γw)・Δwm (10).

On the other hand, the nth or final horizontal rolling mill in the rough rolling mill group (in the example, the sixth horizontal rolling mill R ₆ )
The width deviation ΔD _Ro of the fluctuating portion on the output side can be expressed as in equation (11) by repeatedly applying equation (9) up to the mth point.

ΔD _Ro = (γw−γ)・(ΔW _Eo +γw・ΔW _Eo−1 +…+γw ^nm−1・ΔW _En+1 ) +γw ^nm・ΔD _Rn …(11) In equation (11) above, use equation (10) By substituting the indicated ΔD _Rn , the width deviation ΔD _Ro at the outlet side of the rough rolling mill group when the roll opening degree is corrected in the m-th vertical rolling mill is (12)
It can be expressed as follows.

ΔD _Ro = (γw−γ)・(ΔW _Eo +γw・ΔW _Eo−1 +…+γw ^nm−1・ΔW _En+1 ) +γw ^nm {(γw−γ)・ΔW _Eo +γw・ΔD _Rn−1 −(1 −γw)Δwn} = (γw−γ)・(ΔW _En +γw・ΔW _Eo-1 +…+γw ^nm・ΔW _En ) +γw ^n-m+1・ΔD _Rn-1 −γw ^nm・(1−γw)Δwm ...(12) Therefore, the width reduction amount for the fluctuating part when compared with the width reduction amount for the non-fluctuation part in the m-th vertical rolling mill, which is required to make the width deviation ΔD _Ro on the exit side of the rough rolling mill group zero, is The amount of increase Δwm in width reduction amount is given by equation (13).

Δwm=1/γw ^nm (1−γw)・{(γw−γ)・(ΔW _Eo-1 +…+γw ^nm・ΔW _En ) +γw ^n-m+1・ΔD _Rn-1 } …(13) Therefore In the m-th vertical rolling mill, by controlling the roll opening degree so that the width reduction amount for the variable section is increased by Δwm given by the above equation (13) than the width reduction amount for the non-variable section, the rough rolling mill group The width deviation ΔD _Ro on the exit side can be made zero.
However, the specific change amount ΔS _En of the roll opening degree may be controlled so that it can be expressed by equation (14), where Q is the slope of the plasticity curve and K is the mill rigidity coefficient of the m-th vertical rolling mill.

ΔS _En =K+Q/K(Δwm+ΔD _En ) …(14) However, ΔD _En : Width deviation when the roll opening degree is not adjusted in the m-th vertical rolling mill Since Δwm≫ΔD _En , the above (14) The equation can be rewritten as equation (15) below.

ΔS _En =K+Q/K・Δwm…(15) The above explanation was obtained based on the results obtained by measuring the strip width at the (m-1)th horizontal rolling mill exit side from the roughing mill entry side. The case where the width deviation of the rolled material is controlled by the m-th vertical rolling mill has been shown, but it goes without saying that the roll opening degree may be controlled by any of the m-th vertical rolling mills. be.

Next, the material to be rolled 1 is placed on the exit side of the rough rolling mill group,
Vertical rolling mill E ₅ to roll to a predetermined target width W ₆ ^
The calculation process of the roll opening correction amount will be explained based on the flowchart shown in FIG.

First, the width, thickness, and temperature of the rolled material 1 supplied to the vertical rolling mill E ₁ , for example, the slab, or the target width of the rolled material 1 at the exit side of the roughing mill group, and each horizontal rolling mill R ₁ ~R ₅ The target width at the middle of each exit side, other rolling conditions, etc. are stored in advance in the computer 3 using the input device 4 as appropriate.

First, let the plate width W ₄ of the rolled material 1 at the input side of the vertical rolling mill E ₄ be the average width w _3A (actually measured average value of the total width 2) of the rolled material 1 at the exit side of the horizontal rolling mill R ₃ ( ), for vertical rolling mill E ₄ , based on the roll opening controlled as described above (and for vertical rolling mill E 4).
For E ₅ to _{E 6} , the vertical rolling mill E ₄ (hereinafter generalized as _Ej (j = 4 to 6))
The rolling load P ₄ (also referred to as Pj) is calculated based on the following formula (16) (). In other words, the rolling load Pj is Pj=1.15Kfm・ld・Hj・Qp/1000...(16) Qp=(1−e ^-10.8Hj/Wj ) ・{0.24ld/(Wj−2/3ΔW _Ej ) +0.28( Wj−2/3ΔW _Ej )/ld+0.39} However, Kfm: Average deformation resistance ld: Projected contact arc length Hj: Plate thickness at the entrance of the vertical rolling mill ΔW _Ej : Width reduction amount (Wj−S _Ej ) Wj: Vertical rolling mill Inlet side plate width From this rolling load Pj and mill rigidity Mj, the width reduction amount ΔW _Ej of the rolled material 1 by the vertical rolling mill Ej is calculated based on the following formula (17) ().

∆W _Ej = Wj - (S _Ej + Pj / Mj) ... (17) Apply this width killing amount ∆W _Ej to ∆W _Ej in step () and repeat in a loop until convergence in step ~, and finally set Pj and ∆W _Ej . demand. Then, based on the width reduction amount ΔW _Ej , the strip width Wj at the entrance side of the vertical rolling mill Ej, and the bulge width expansion amount w _Mj given by the above equation (3), the strip width w _j at the exit side of the horizontal rolling mill Rj.
Calculate (). Next, this plate width w _j is set as the plate width W _j+1 of the rolled material 1 at the entrance side of the vertical rolling mill E _j+1 (), and this is repeated sequentially from j = 4 to j = 6 to form the rough rolling mill group. The average plate width w _6A of the rolled material 1 at the exit side of the horizontal rolling mill R ₆ is predicted and calculated, and this predicted average width w _6A and the rolled material 1 at the exit side of the rough rolling mill group are calculated in advance. Set target width
The difference Δ _w6 from W ₆ is determined (), and it is examined whether the absolute value of this difference exceeds the tolerance range δ (for example, 0.1 mm) ().

If this condition is not met (NO), the heap width expansion coefficient γ ₅ (for example, a value of 0.6 to 0.9) in the vertical rolling mill E ₅ and the horizontal rolling mill R ₅ and the rolled material 1 on the exit side of the horizontal rolling mill R ₆ Using the difference _{Δ w6 between the} predicted average _width w _{6A of} Approximate width reduction amount ΔW _E5 as ΔW _E5 +
Correct it as Δ _w6 /(1-γ ₅ ) () and return to step (). Then, the process from step to is repeated until the condition is satisfied. However, in this iterative process from j=5 to j=6, if j=5, a loop is used in which step 2 is omitted. If the step condition is satisfied (YES), the rolling load P ₅ of the vertical rolling mill E ₅ is calculated (), and the rolling load P ₅ and the mill stiffness M ₅ are combined with the plate at the entrance side of the vertical rolling mill E ₅ . Calculate the roll opening S _{E5 *} of the vertical rolling mill E ₅ based on the width W E5 and the formula S _E5 * = W _E5 − P ₅ / M ₅ (), then calculate the roll opening S _E5 * and the rolling schedule. Calculate the roll opening correction amount ΔS _E5 of vertical rolling mill E ₅ based on the initial roll opening S E5 determined by the formula ΔS _E5 = S _E5 *−S _E5 , and calculate the roll opening correction amount ΔS _E5 of vertical rolling mill E ₅ Correctly control the opening.

Next, the results of implementing the method of the present invention will be explained. In the example, the slab width was 1250 mm, the slab thickness was 270 mm, and the target width on the roughing mill outlet side was 1207 mm.

FIG. 4A is a graph showing the results of actually measuring the strip width of the rolled material obtained by the method of the present invention from the tip to the rear end on the exit side of the rough rolling mill, and the thick line in the figure indicates the width of the rolled material obtained by the method of the present invention. The thin line indicates the target width, and the broken line indicates the result obtained only by controlling the width deviation by the vertical rolling mill.

As is clear from this graph, the strip width of the rolled material obtained by the method of the present invention matches the target value, whereas simply controlling the width deviation does not reduce the strip width variation difference itself. Although the problem has been resolved, the average width still deviates by about 3 mm compared to the target width. For reference, the measured width of the material to be rolled obtained by the conventional method using one vertical rolling mill on the exit side of the rough rolling mill group is shown in FIG. 4B. Figure 4 (b) is a graph showing the results of actual measurements of the strip width of the rolled material obtained by the conventional method from the tip to the rear end on the outlet side of the rough rolling mill group, and the thick line in the figure indicates the width of the material to be rolled obtained by the conventional method. The measured width of the obtained rolled material is shown, the thin line shows the target width, and the broken line shows the case without control. As is clear from this graph, in the case of no control, the average width is 3 mm wider than the target width, and the plate width variation is 5 mm. It can be seen that although both the amount of fluctuation has been improved compared to the case without control, the amount of sheet width fluctuation has not been sufficiently resolved.

FIG. 5A is a histogram showing the distribution of the deviation between the average width and the target width in the rolled material obtained by the method of the present invention, and FIG.
These are similar histograms when the average width is not controlled to match the target width, and in both of these histograms, the vertical axis shows the number of rolled coils, and the horizontal axis shows the width deviation value on the rough rolling mill group exit side. ing. As is clear from these histograms, in the case of the method of the present invention, only the width deviation is controlled;
It can be seen that the width deviation of each rolled coil is very small compared to the case where no control is performed to match the average width with the target width.

As described above, in the method of the present invention, the control of the width deviation and the control of the average width are performed by separate vertical rolling mills, so the average width of the rolled material greatly exceeds and falls below the target width. Even in such a case, problems such as overloading of the vertical rolling mill or uncontrollable strip width will not occur, and the present invention can improve the predicted average width of each part in the longitudinal direction of the rolled material on the exit side of the rough rolling mill group. Roll opening control to make the width deviation from the rough rolling mill group zero to zero, and roll opening setting correction control to make the predicted average width at the exit side of the rough rolling mill approximately equal to the target width are both located downstream of the width gauge. Since the so-called feed forward control is performed in the vertical rolling mill A and the vertical rolling mill B located further downstream from the vertical rolling mill A, the present invention has excellent effects such as high control accuracy. be.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an apparatus for carrying out the method of the present invention and its control system; FIG. 2 A, B, and C are explanatory diagrams showing the relationship between width reduction in vertical rolling and width expansion in horizontal rolling; Fig. 3 is a flowchart showing the process of calculating the roll opening correction amount in the vertical rolling mill in order to make the average width of the rolled material match the target width on the exit side of the rough rolling mill group, and Fig. 4 A shows the invention of the present invention. A graph showing the change in the width of the entire rolled material whose width was controlled by the conventional method; FIG. Figure 5(a) is a histogram showing the relationship between the number of coils and width deviation of the rolled material whose width was controlled by the method of the present invention, and Figure 5(b) is a histogram showing the relationship between the number of coils and the width deviation of the rolled material whose width was controlled by the method of the present invention. A histogram showing the relationship between the number of coils and the width deviation, Figure 6 is a schematic diagram showing the device and its control system for implementing the conventional strip width control method, and Figures 7 A and B also show the same strip width control. It is a graph which shows the aspect of this. DESCRIPTION OF SYMBOLS 1... Material to be rolled, 2... Width meter, 3... Computer, _E1 to _E6 ... Vertical rolling mill, _R1 to _R6 ... Horizontal rolling mill.

Claims (1)

[Claims] 1. In a hot rough rolling mill group consisting of a plurality of vertical rolling mills and a plurality of horizontal rolling mills arranged alternately, a width meter placed on the exit side of the horizontal rolling mill in the middle of the rough rolling mill group. Measure the plate width of each part in the longitudinal direction of the rolled material, and based on this measured value, calculate the actual average width of the rolled material at the exit side of the horizontal rolling mill and the width deviation from the actual average width of each part of the rolled material in the longitudinal direction. At the same time, calculate the predicted average width at the exit side of the rough rolling mill group predicted based on the measured average width, and calculate the width deviation from the predicted average width at the exit side of the rough rolling mill group predicted based on the width deviation. In a vertical rolling mill A located on the downstream side of the width gauge, the roll opening degree is controlled during rolling of the material to be rolled, and the roll opening degree is controlled to be zero. Also, in the downstream vertical rolling mill B, the roll opening of the vertical rolling mill B is adjusted before the tip of the material to be rolled reaches the vertical rolling mill B so that the predicted average width at the outlet side of the rough rolling mill group is approximately equal to the target width. A plate width control method characterized by modifying a set value.