JP2019107675A - Control device and control method for rolling mill - Google Patents

Abstract

To reliably suppress meandering of a tail end part when rolling a steel plate.SOLUTION: A control device 10 which is applied to a rolling mill for finishing a hot rolling line, and controls an amount of meandering of a rolled material. This control device comprises: a plate thickness profile measurement unit 11 which measures a width direction plate thickness on an inlet side and an outlet side of a rolling stand 60 of the rolled material; and leveling means which changes an amount of leveling of the rolling mill according to the measured width direction plate thickness on the inlet side and the outlet side of the rolling stand of the rolled material.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device and control method of a rolling mill.

  Conventionally, the material to be rolled during rolling is not stably present at the center in the width direction of the rolling roll, and moves to the width direction end of the rolling roll as rolling progresses (called meandering) Is well known. In particular, when the tail end of the material to be rolled falls off, the rolling material collides with the side guide and the edge is broken and rolled, a problem that a rolling trouble called so-called "squeezing" occurs. There is.

  As meandering control technology of hot finishing rolling that has been put into practice so far, for example, the load difference between the drive side and the work side of the rolling mill disclosed in Patent Document 1 and Patent Document 2 is used for the drive side and the work side. There is known a technique (generally called "differential load type meander control") of controlling the roll reduction device of the above.

  For example, Patent Document 2 describes controlling the leveling amount ΔS of the rolling mill using the parallel stiffness value K of the rolling mill represented by the following formula (2). The parallel stiffness value K is an index indicating the ease of maintaining the parallelism of the upper and lower rolls when there is a load difference between the drive side and the work side of the rolling rolls, and is defined by the following equation (3).

  In the above equation (2), β is a control gain (tuning factor), and ΔP is a difference (rolling load difference) between the rolling load on the drive side and the rolling load on the working side of the rolling rolls. In the above equation (3), Sdf is the difference in roll opening (rolling screw position) between the driving side and the working side of the rolling roll. That is, ΔP / K represents the deviation in the width direction of the roll opening in the rolling roll.

  And when a to-be-rolled material meanders during rolling, rolling load difference (DELTA) P arises between the drive side and working side of a rolling mill. In this case, on the side where the rolling load is high among the drive side and the work side, that is, the side where the material to be rolled meanders, the degree of roll opening becomes large and the amount of reduction decreases. As a result, a difference occurs in the reduction amount of the material to be rolled between the driving side and the work side of the rolling rolls, and a difference occurs in the lateral velocity of the material to be rolled, so that the material to be rolled is rotated. And when the to-be-rolled material which inclines advances a rolling line, the amount of meanders will increase as advancing of a to-be-rolled material, and this will generate a further larger meander. Therefore, the amount of meandering increases at an acceleration.

  On the other hand, in the differential load method meandering control described in Patent Document 2, the upper and lower roll intervals in the rolling roll are made parallel by correcting the deviation in the width direction of the roll opening degree using the above equation (2). It is possible to maintain and control the meandering of the material to be rolled.

  In addition, while rolling the steady part of the material to be rolled, the material to be rolled on the rolls of the upstream rolling stand even if the rolling reductions differ between the working side and the drive side of the rolling roll, even if factors causing the meandering occur. Is restrained and meandering is suppressed. However, when the tail end passes through the upstream rolling stand, the restraint of the material to be rolled is removed, so that the unbalance at both ends, which has been latent, may become apparent at once, resulting in a large meander.

  From such a background, Patent Document 3 proposes a technique for detecting the cause of the occurrence of meandering during rolling of the steady portion and suppressing the occurrence of meandering at the tail end.

  In the method described in Patent Document 3, the width direction distribution of the tension of the material to be rolled is detected by measuring the load acting on the looper between the rolling stands, and the tension is corrected by leveling. The meandering is caused by the difference between the rolling reductions on the working side and the driving side of the rolling rolls, and the tension between the rolling stands decreases on the side where the rolling reduction is large. Therefore, it becomes possible to prevent the occurrence of meandering by detecting the tension difference with the looper between the rolling stands and controlling the leveling amount so that the difference in tension between right and left disappears.

JP-A-49-133256 JP-A-52-124453 JP, 2004-243376, A

  However, in the differential load method meandering control described in Patent Document 1 and Patent Document 2, since the control of the roll opening difference is performed based on the load difference generated as a result of the meandering, the meandering can not be prevented in advance. When the rolling load difference ΔP between the driving side and the working side of the rolling rolls is detected, the material to be rolled is already meandered, so the differential load method meandering control only corrects the meandering that has already occurred. Furthermore, the control response of the roll opening difference can be made faster by setting the control gain (tuning factor) β in the above equation (2) to a large value, but in this case it is overcorrected. Control is unstable. As described above, there is a limit to following the meandering that has already occurred in the differential load method meandering control.

  Further, in the method described in Patent Document 3, in order to prevent occurrence of meandering, the left-right pressure reduction balance is made so that the left-right difference in tension measured while rolling the steady part, that is, the left-right difference in the amount of pressure reduction. Fix it. However, since the left-right difference in tension between the rolling stands is a result of rolling on both the upstream and downstream sides, which one of the upstream and downstream rolling mills should be corrected for left-right pressure reduction is 1 The tension difference between two rolling stands alone can not be determined.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a control device and control method of a rolling mill which can reliably suppress occurrence of meandering of a tail end portion during rolling.

  The control device for a rolling mill according to the present invention is a control device for controlling the meandering amount of a rolled material, and is a plate thickness profile measuring means for measuring the width direction plate thickness profile on the rolling stand entering side and outgoing side of the rolling material. And leveling control means for changing the leveling amount of the rolling mill in accordance with the width direction plate thickness profiles of the rolled material measured on the inlet side and the outlet side of the rolling stand.

  The control method of a rolling mill according to the present invention is a control method for controlling the meandering amount of a rolled material, and is a plate thickness profile measuring step of measuring a width direction plate thickness profile on the rolling stand entering side and outlet side of the rolling material. And a leveling control step of changing the leveling amount of the rolling mill according to the width direction plate thickness profiles at the rolling stand inlet side and the outlet side of the rolled material measured.

ただし、式（１）において、Ｈ_ｉｎは圧延機入側の幅方向中央板厚、Ｈ_ｏｕｔは圧延機出側の幅方向中央板厚、ｉは圧延材板幅方向の評価点、Ｎは圧延材板幅方向の評価点の総数、Ｗ_ｉｎ，ｉは圧延材板幅方向の評価点ｉでの圧延機入側板ウェッジ、Ｗ_{ｏｕｔ，ｉ}は圧延材板幅方向の評価点ｉでの圧延機出側板ウェッジ、α_ｉはチューニング率である。 The control method of a rolling mill according to the present invention is characterized in that, in the above-mentioned invention, the leveling control step includes a step of obtaining a leveling amount ΔS of the rolling mill based on the following formula (1).

However, in the equation (1), H _in is the width direction central plate thickness on the rolling mill entrance side, H _out is the width direction central plate thickness on the rolling mill exit side, i is an evaluation point of the rolled material sheet width direction, and N is the rolling The total number of evaluation points in the width direction of the sheet, W _{in, i} is the wedge on the side of the rolling mill at the evaluation point i in the width direction of the rolled material, W _{out, i} is the rolling mill at the evaluation point i in the width direction of the rolled material The exit plate wedge, α _i is the tuning rate.

  According to the present invention, by controlling the leveling amount in accordance with the plate thickness profiles on the entry side and the exit side of the rolling stock, it becomes possible to suppress the occurrence of the meandering of the tail end.

FIG. 1 is a schematic view showing an example of a hot rolling line applied in the embodiment. FIG. 2: is a figure which shows typically the control apparatus of the rolling mill in embodiment. FIG. 3 is a view for explaining a plate wedge of a rolled material. FIG. 4 is a diagram showing the number of occurrences of the narrowing-down trouble in the first embodiment. FIG. 5 is a diagram showing the number of occurrences of the narrowing-down trouble in the second embodiment.

  Hereinafter, with reference to the drawings, a control device and a control method of a rolling mill in an embodiment of the present invention will be specifically described. In addition, this embodiment makes an example the case where it applies to a hot rolling line.

[1. Hot rolling line]
FIG. 1 is a schematic view showing an example of a hot rolling line applied in the embodiment. In the hot rolling line 1, the material to be rolled (slab) 3 heated in the heating furnace 2 is subjected to width reduction by the width reduction device 4 and then to a predetermined thickness by the rough rolling mill 5 usually about 2 to 5 Rolled. Thereafter, the material to be rolled 3 which has been further thinly rolled by the finish rolling mill 6 is water cooled by the water cooling device 8 and rolled up in a coil shape by the coiler 9 while the runout table 7 is being inserted. The coil is then cooled to ambient temperature in the coil yard.

[2. Control device of rolling mill]
FIG. 2: is a figure which shows typically the control apparatus of the rolling mill in embodiment. The control device 10 of the rolling mill is a control device for controlling the meandering amount of the material to be rolled 3 at the time of rolling by the finish rolling mill 6 and suppressing the occurrence of meandering of the tail end in advance. When controlling the leveling amount ΔS of the finishing mill 6, the control device 10 manipulates the leveling amount ΔS according to the change in the width direction plate thickness profile on the entering side and the exiting side of the rolling stand during steady-state rolling. Is configured as. The leveling amount ΔS is the difference between the rolling reductions on the working side and the driving side of the rolling rolls of the finish rolling mill 6, which is the difference between the rolling position on one of the working side and the driving side minus the other rolling position. It is defined. The drive side is the side on which the roll drive motor is attached to the roll end of the rolling roll, and the working side is the opposite side. Note that "left and right", "width direction" and "plate width direction" described in this description are synonymous.

  In detail, the finish rolling mill 6 is constituted by a plurality of rolling stands 60, and the leveling amount ΔS can be adjusted by the pressure reduction devices 61 provided on the respective stands. The rolling stand 60 shown in FIG. 2 is configured of a four-high rolling mill including work rolls 60a and reinforcing rolls 60b. The pressure reduction device 61 is controlled by the controller 10.

  The control device 10 measures the thickness direction thickness profile of the material to be rolled 3 at the entry side and the exit side of the rolling stand 60 by the plate thickness profile measuring device 11 while rolling the material to be rolled 3 by the finish rolling mill 6 . The plate thickness profile measuring device 11 is configured to transmit X-rays to the material to be rolled 3 and measure the thickness of the material to be rolled 3.

  As shown in FIG. 2, the plate thickness profile measuring device 11 includes an inlet plate thickness profile measuring device 11 a disposed on the inlet side of the rolling stand 60 and an outlet plate disposed on the outlet side of the rolling stand 60. And a thickness profile measuring device 11b. The plate thickness profile measuring device 11 a on the entry side measures the width direction plate thickness profile of the material to be rolled 3 at the entry side of the rolling stand 60. The plate thickness profile measuring device 11 b on the outlet side measures the width direction plate thickness profile of the material to be rolled 3 at the outlet side of the rolling stand 60.

  Then, the width direction plate thickness profiles (measurement values) measured by the plate thickness profile measuring devices 11 a and 11 b on the input side and the output side are input to the computing device 12. The control device 10 calculates the amount of change between the width direction thickness profile on the input side and the width direction thickness profile on the output side based on those measured values, and the finish rolling mill according to the amount of change. The leveling amount ΔS of 6 is controlled. When the plate thickness profile measuring device 11a on the ingress side and the plate thickness profile measuring device 11b on the outlet side are not particularly distinguished, they are collectively referred to as a plate thickness profile measuring device 11.

  The arithmetic unit 12 is constituted by an arithmetic computer having a CPU and a storage device, and performs various arithmetic processing based on the information input from the thickness profile measuring device 11 and the information stored in the storage device. The pressure reduction device 61 is controlled according to the calculation result. Specifically, computing device 12 performs leveling of finish rolling mill 6 according to the width direction plate thickness profile on the entry side and the exit side of rolling stand 60 of material to be rolled 3 measured by plate thickness profile measuring device 11 A leveling control means is provided to change the amount ΔS. In the control device 10 as a whole, the arithmetic device 12 and the pressure reduction device 61 can be collectively referred to as leveling control means.

  And in this embodiment, leveling amount (DELTA) S is operated according to the change of the width direction board thickness profile in the entrance side of the rolling stand 60 in rolling and the output side in rolling. Since the meandering of the rolled material is caused by the left / right difference of the reduction amount, that is, the left / right difference of the elongation by rolling, the width direction plate thickness deviation (difference between the plate thickness at each position in the plate width direction and the plate width central plate thickness) By operating the leveling amount ΔS so that there is no change before and after rolling, the occurrence of meandering can be prevented in advance.

[3. Control method of rolling mill]
Here, the control method of the rolling mill in the embodiment will be described. This control method is implemented by the control device 10 described above.

First, with reference to FIG. 3, a plate wedge of a rolled material will be described. The evaluation point i in the plate width direction is determined according to the distance from the plate edge, for example, 25 mm (i = 1), 75 mm (i = 2), 200 mm (i = 3) from both ends of the rolled material plate Do. And board wedge W expresses the right-and-left difference of board thickness H of the board width direction center, and board thickness in each evaluation point i. Plate wedge _{W in} at the entry side of the rolling _{mill, i} the plate wedge _{W out} at the delivery side of the rolling _mill, expressed by the _i. In the example shown in FIG. 3, the difference between the working-side plate thickness difference dH _Fi and the driving-side plate thickness difference dH _Di at each evaluation point i with respect to the plate width central plate thickness H _out on the outlet side of the rolling mill It represents. W _{out, 1} = dH _F1 -dH _{D1 at} the i = ₁ evaluation point, W _{out, 2} = dH _F2 -dH _{D2 at} the i = ₂ evaluation point, W _{out, 3} = dH _F3 at the i = 3 evaluation point It can be expressed as -dH _D3 . The larger the number of evaluation points i, the better. However, the difference in plate thickness in the width direction is small near the center of the plate width, and it is easily affected by plate thickness measurement errors. It is desirable to do.

Next, a method of calculating the leveling amount ΔS will be described. The leveling amount ΔS is determined by the following equation (1) using the weighting coefficient α _i of the evaluation point i in the sheet width direction.

In the above equation (1), ΔS is the leveling amount [mm], H _in is the width direction central plate thickness at the rolling mill entrance side [mm], H _out is the width direction central plate thickness at the rolling mill exit side [mm], i Is the evaluation point in the rolling material width direction, N is the total number of evaluation points in the rolling material width direction, W _{in, i} is the rolling mill entrance side plate wedge [mm] at the evaluation point i in the rolling material width direction, W _{out , I} is a rolling mill outlet side plate wedge [mm] at an evaluation point i in the rolled material sheet width direction, and α _i is a weighting coefficient of the width direction evaluation point.

The leveling amount ΔS is the difference in roll pressure between the working side and the driving side. The weighting factor α _i is a parameter which determines which position in the plate width direction the wedge change is to be emphasized to use the meandering control. The weighting coefficient α _i may be set according to the plate thickness, plate width, and rolling load, but it is desirable to set the range of 50 to 200 mm largely from the plate end.

  Then, the computing device 12 shown in FIG. 2 calculates the leveling amount ΔS using the above equation (1), and outputs a command signal corresponding to the leveling amount ΔS to the pressure reducing device 61.

[4. Example 1]
In the first embodiment, the above-described embodiment is applied to a hot rolling line 1 provided with a finishing rolling mill 6 having a total of seven stands of F1 to F7 in a four-high rolling mill including work rolls and reinforcing rolls. Did. The equipment specifications of the finish rolling mill 6 in Example 1 are shown in Table 1.

Moreover, in Example 1, as a material to be rolled 3, a hot-rolled sheet of low carbon steel having a plate thickness of 1.2 to 3.0 mm and a plate width of 1000 to 1200 mm was used. And the hot-rolled sheet (rolling material 3) was hot-rolled, and the incidence rate of the narrowing-down trouble of the tail end part was investigated. The coil investigated is 832 coils. Furthermore, in Example 1, the plate width direction evaluation points were set to three points of 25 mm, 75 mm, and 150 mm from the plate end, α ₁ was set to 3.0, α ₂ to 3.2, and α ₃ to 3.0. On the other hand, as a prior art (conventional example), rolling was performed on a hot-rolled steel plate of substantially the same size with the tuning ratio β set to 1.0 in the above equation (2).

  FIG. 4 is a diagram showing the number of occurrences of the narrowing-down trouble in the first embodiment. As shown in FIG. 4, the generation number ratio of Example 1 (invention) was 0.1% with respect to 1.1% of the generation number ratio of the conventional example. From this verification result, it has been found that by applying the above-described embodiment to the hot rolling line 1, it is possible to reduce the occurrence number rate of narrowing-down troubles by about 90% compared to the conventional example.

[5. Example 2]
In the second embodiment, a finishing mill 6 having a total of seven stands where the four-high rolling mill consisting of work rolls and reinforcing rolls is F1 to F4 and the six-high rolling mill consisting of work rolls, intermediate rolls and reinforcing rolls is F5 to F7 The above-described embodiment was applied to the hot rolling line 1 provided with the above to verify. The equipment specifications of the finish rolling mill 6 in Example 2 are shown in Table 2.

  Moreover, in Example 2, the hot rolled sheet of low carbon steel of 1.8 to 2.4 mm in plate thickness and 1200 to 1300 mm in plate width was targeted as the material to be rolled 3. And the hot-rolled sheet was hot-rolled and the incidence rate of the narrowing problem of the tail end was investigated. The coils investigated are 611 coils. The conventional example is the same as the conventional example in the first embodiment described above.

  FIG. 5 is a diagram showing the number of occurrences of the narrowing-down trouble in the second embodiment. As shown in FIG. 5, the generation number ratio in Example 2 (the present invention) was 0.05% with respect to the generation number ratio of 0.85% in the conventional example. From this verification result, it has been confirmed that the rate of occurrence of the narrowing-down trouble can be dramatically reduced as compared with the conventional example.

  As described above, according to the embodiment, it is possible to suppress the occurrence of meandering at the tail end by controlling the leveling amount in accordance with the plate thickness profiles of the rolling stand on the entry side and the exit side of the rolling material. .

  Further, the leveling amount ΔS according to the embodiment can obtain a great effect in suppressing the meandering of the tail end by operating immediately before rolling the tail end. The invention is not limited to this operation timing, and the operation may be performed a plurality of times in combination with the case where the leveling operation of the upstream stand is performed in rolling at the steady portion.

  In addition, this invention is not limited to embodiment mentioned above, It can change suitably in the range which does not deviate from the objective of this invention.

  For example, the plate thickness profile measuring apparatus 11 may use γ rays in the upstream stand having a large plate thickness in addition to the X-rays. Moreover, since the measurement range only needs to cover the evaluation point i in the plate width direction, it is not necessary to measure the plate thickness in the entire region in the plate width direction of the material to be rolled 3. Furthermore, the plate thickness profile measuring device 11 is not limited to a plate thickness measuring device by X-ray transmission. For example, it may be a plate thickness profile measuring device 11 configured by a laser range finder or the like.

Reference Signs List 1 hot rolling line 3 material to be rolled 6 finishing rolling machine 10 control device 11 plate thickness profile measuring device 12 arithmetic device 60 rolling stand 60 a work roll 60 b reinforcing roll 61 reduction device

Claims (3)

A control device for controlling the amount of meandering of a rolled material, wherein
Plate thickness profile measuring means for measuring the width direction plate thickness profile of the rolled material on the inlet side and the outlet side of the rolling stand;
A control device for a rolling mill, comprising: leveling control means for changing a leveling amount of the rolling mill according to width direction plate thickness profiles on the rolling stand inlet side and outlet side of the measured rolling material. A control method for controlling the meandering amount of a rolled material, comprising
A plate thickness profile measuring step of measuring the width direction plate thickness profile of the rolled material on the inlet side and the outlet side of the rolling stand;
A control method of a rolling mill, comprising: a leveling control step of changing a leveling amount of the rolling mill according to a width direction plate thickness profile on the rolling stand entering side and the outlet side of the measured rolling material. The control method of the rolling mill according to claim 2, wherein the leveling control step includes a step of obtaining a leveling amount? S of the rolling mill based on the following expression (1).

However, in the equation (1), H _in is the width direction central plate thickness on the rolling mill entrance side, H _out is the width direction central plate thickness on the rolling mill exit side, i is an evaluation point of the rolled material sheet width direction, and N is the rolling The total number of evaluation points in the width direction of the sheet, W _{in, i} is the wedge on the side of the rolling mill at the evaluation point i in the width direction of the rolled material, W _{out, i} is the rolling mill at the evaluation point i in the width direction of the rolled material The exit plate wedge, α _i is the tuning rate.

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