JPH08192209A - Method for hot-rolling strip - Google Patents

Abstract

PURPOSE: To provide a hot rolling method by which the variation of width in the longitudinal direction of a strip which is produced at the time of accelerating rolling in a finishing mill is effectively suppressed without depending on the impartation of tension which needs complicated descriptive procedure or the like in hot rolling with a hot rolling mill line on which a roughing mill and finishing mill are arranged. CONSTITUTION: The variation of width of a strip S at a finishing mill 7 is beforehand predicted and the compensation ΔWR of the width of a rough bar B on the inlet side of the finishing mill 7 is determined from this variation of width. Based on this compensation ΔWR, the opening degree W(x) of an edger 6a of the roughing mill 6 is controlled and the width of the rough bar B which is rolled with the roughing mill 6 is changed in accordance with the compensation ΔWR in the longitudinal direction. In this way, the variation of width at the finishing mill is compensated by the width of the rough bar on the inlet side of the finishing mill and the variation of width of the strip is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of hot-rolled coils in a hot rolling mill line, and more particularly to the hot strip rolling which can control strip width variation during accelerated rolling in a finishing rolling mill. Hot rolling method.

[0002]

2. Description of the Related Art Generally, in hot strip rolling, variations in rolling conditions such as acceleration / deceleration rolling in a finish rolling mill cause variations in strip width behavior between roll stands and roll bites, resulting in finish rolling. The width of the board on the exit side fluctuates in the longitudinal direction. In the past, it was considered effective to apply a constant tension to the strips between the roll stands in order to suppress the strip width variation. As the temperature rises toward the end and the unit tension between the roll stands (tension per unit cross-sectional area of the strip) is kept constant, the strip width at the rear end of the strip becomes narrower than desired. Therefore, in order to suppress such plate width variation, for example, in Japanese Patent Laid-Open No. 5-185126, the deformation resistance of the strip per unit cross-sectional area in the roll bite of each roll stand is calculated, and based on the deformation resistance. There has been proposed a strip hot rolling method in which an appropriate tension is calculated and applied to the strip.

[0003]

However, although the effect of suppressing the strip width variation by the application of the appropriate tension is recognized, as a factor of the strip width variation in the strip longitudinal direction in hot rolling, the above-mentioned conventional technique (Japanese Patent Laid-Open No. Hei. -185126) In addition to the change in deformation resistance which is the basis of the tension calculation,
For example, a change in the crown may be considered, and setting tension in consideration of the influence of these fluctuation factors is very complicated. Therefore, only by applying tension, the strip width variation in the finish rolling mill including various factors due to changes in the rolling conditions that occur during accelerated rolling, that is, the strip width at the strip rear end becomes narrower than the desired length It is difficult to effectively suppress the variation of the strip width in the direction and stably obtain a desired finish rolling mill delivery side strip width.

The present invention has been made in view of the above-mentioned problems of the prior art. For example, a tension change requiring a complicated setting procedure is applied to the strip width variation in the strip longitudinal direction that occurs during accelerated rolling in a finish rolling mill. It is an object of the present invention to provide a strip hot rolling method that can be effectively suppressed without depending on

[0005]

In order to achieve the above object, the present invention has the following constitution. That is, the strip hot rolling method according to the present invention is a method for continuously rolling a strip by a hot rolling mill line including at least one rough rolling mill having an edger on the inlet side and a finishing rolling mill. In the hot rolling method, in advance, predict the strip width variation that occurs during accelerated rolling in the finish rolling mill, and obtain the compensation amount for the rough bar width on the entry side of the finish rolling mill from the predicted value of this strip width variation. The opening of the edger of the rough rolling mill is controlled based on this compensation amount, and the width of the rough bar rolled by the rough rolling mill is changed in the longitudinal direction according to the compensation amount.

[0006]

In hot strip rolling, as described above, the width behavior of the strip between the roll stands varies due to variations in the rolling conditions during accelerated rolling in the finish rolling mill.
On the strip on the delivery side of the finish rolling mill, a strip width variation (width reduction from the strip front end T to the rear end B) ΔW occurs as shown in the graph of FIG. On the other hand, the plate width variation value, that is, the difference ΔW between the maximum width of the front end portion T and the minimum width of the rear end portion B differs depending on the steel type, but a general mild steel material is taken as an example [(a) in FIG. 3]. As shown in the graphs in the figure and (b), the strip size (thickness and width) has a strong correlation and can be predicted from the actual values or theoretical calculation values of the preceding rolled material for each steel type. Therefore, predict the strip width variation in the finish rolling mill, obtain the compensation amount for the rough bar width on the entry side of the finishing rolling mill to reduce the strip width variation amount to zero, and use the compensation amount based on this compensation amount. By controlling the width of the rough bar rolled in the longitudinal direction, it is possible to suppress the strip width variation. Here, in the present invention, the plate width variation amount in the finish rolling mill is predicted in advance, the rough bar width compensation amount is obtained from the predicted value of the plate width variation amount, and the rough bar width corresponding to the compensation amount is calculated. Since the edger opening of the rolling mill is changed, the strip width variation that occurs during accelerated rolling in the finishing rolling mill is compensated by the rough bar width on the entry side of the finishing rolling mill to suppress strip width variation. can do.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the hot rolling method according to the present invention will be described below with reference to the drawings. [FIG. 1] is an explanatory view of rolling equipment and control of the present embodiment, in which (a) is a schematic explanatory view of an applied hot rolling mill line, and (b) is an edger opening control pattern. It is a drawing shown. The hot rolling mill line in this embodiment shown in (a) of FIG. 1 includes a continuous heating furnace (1),
Vertical rolls (2), edgers (3a), (4a),
Finishing rolling mill (7) consisting of four rough rolling mills (3), (4), (5), (6) provided with (5a) and (6a) and seven stands (7a) to (7g)
Will be deployed. In this hot rolling mill line, the material (M) heated to a predetermined temperature in the continuous heating furnace (1) is transferred to the rough rolling mill (2),
(3), (4), (5), (6) rough rolling into a rough bar (B), the rough bar
(B) is sent to the finish rolling mill (7) and finish-rolled into a strip (S) of a predetermined size.

Here, the material in the hot rolling of the present embodiment
(M) is general mild steel, and the target size on the exit side of the finishing rolling mill (7) was 1.2 mm thick and 1250 mm wide. As the rolling conditions at this time, the thickness of the rough bar (B) was set to 30 mm, while the unit tension between the stands in the finishing mill (7) was set to 4.9 Mp between the stands (7a)-(7b). , (7b)-(7c) 8.8M
p, (7c)-(7d) 13.7Mp, (7d)-(7e) 21.6Mp, (7e)-
(7f) 28.4Mp, (7f)-(7g) 37.3Mp, finishing mill acceleration rate 10 (m / min) / sec, finishing outlet temperature 850 ° C at the tip, rear end The condition was 880 ° C. Then, in the present example, in advance, the strip width variation amount of the material (M) to be rolled in the finish rolling mill (7) is predicted, and the rough bar (B) width compensation is performed from the estimated value of the strip width variation amount. By determining the amount and changing the opening of the edger of the rough rolling mill in accordance with this compensation amount, the strip width variation that occurs during accelerated rolling in the finishing rolling mill (7) can be determined. (7) Compensation was made with the width of the coarse bar (B) on the input side. The edger opening control at that time can be performed by each of the four rough rolling mills (3), (4), (5), and (6), but in the present embodiment, the downstreammost rough rolling mill (6) is used. The edger (6a) was subjected to opening control corresponding to the above compensation amount.

Further, as a method of obtaining the above-mentioned compensation amount, the strip width variation value of the strip (S ') in the preceding hot rolling in the actual operation, that is, the maximum width of the tip portion T of the preceding strip (S'), The actual value of the difference ΔW from the minimum width of the rear end B is
Amount of compensation for the width of the rough bar (B) on the entry side of the finishing mill (7) of (M) Δ
W was adopted learning control system to be reflected in _R. Specifically, the predicted value of the compensation amount ΔW _R is ΔW _CAL , and the actual value is Δ
_Let W _ACT, and obtain the learning coefficient WFC by the following formula. WFC = (ΔW _CAL −ΔW _ACT ) / ΔW _CAL ----- Then, the i-th WFC is set as WFC _i , and the i + 1-th compensation amount ΔW _{R, i + 1} is calculated by the following formula. ΔW _{R, i + 1} = WFCA _{i + 1} · ΔW _{CAL, i + 1} ----- where WFCA _{i + 1} = α · WFC _i + (1-α) · W
FCA _i and α are smoothing coefficients (0 ≦ α ≦ 1).
The predicted value ΔW _CAL of the compensation amount ΔW _R is given to the strip size and the steel type.
It may be obtained from past actual data or may be a theoretical calculation value. Learning is the same size as the above-mentioned predicted value ΔW _CAL ,
Perform according to steel type.

In this embodiment, the degree of opening of the edger (6a) of the rough rolling mill (6) is controlled based on the compensation amount ΔW _R obtained as described above. The opening control method of the edger at this time will be described with reference to the opening control pattern shown in FIG.
In the figure (b), L _R is the rough bar length, L _RT is the rough bar tip end width compensation length, and is the volume of the strip width change region L _{T at} the tip of the strip shown in FIG. It is the corresponding length. Further, x is the end point A of the rough bar tip width compensation length L _RT.
, W ₀ is a reference opening with respect to the target width of the leading end of the rough rolling mill, and W (x) is a longitudinal edger opening.
This corresponds to the compensation amount ΔW _R. First, the rough bar tip width compensation length L _RT is dealt with by the conventional tip edger compensation control method, and the edger opening W (x) from the terminal point A is calculated according to the following equation. Control. W (x) = {ΔW _R / (L _R −L _RT )} x + W ₀ ----- Here, in the strip size of the present embodiment, as shown in FIG.
From the graph of (b), the plate width variation ΔW is given as 11 mm. Therefore, with ΔW _CAL = ΔW = 11 mm, the compensation amount ΔW _R is obtained by the above-described method, and the opening W (x) of the edger is set and controlled.

As described above, in the present embodiment in which the edger opening of the rough rolling mill is controlled, the variation of the strip width in the finishing rolling mill is compensated by the rough bar width on the entry side of the finishing rolling mill in advance. , Strip width variation of the strip on the output side of the finish rolling mill is ΔW ≤ 3
It was possible to suppress the variation to 8 mm or more and to reduce the plate width variation of 8 mm or more as compared with the case where the method of the present invention was not used, which confirmed the excellent effect of the method of the present invention.

[0012]

As described above, according to the hot rolling method of the present invention, the tension which requires a complicated setting procedure for the strip width variation in the strip longitudinal direction which occurs during accelerated rolling in the finish rolling mill. It is possible to effectively suppress the strip width without depending on the addition of the steel sheet, etc., and thus the strip width of the rolled strip can be stabilized, and the yield can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of rolling equipment and control according to an embodiment of the present invention, in which (a) is a schematic explanatory view of an applied hot rolling mill line, and (a) is an edger opening control pattern. FIG.

FIG. 2 is a graph showing strip width variation in a conventional hot rolling.

FIG. 3 is a graph showing a relationship between a strip width and a target thickness of a strip in a conventional hot rolling and a width shrinkage amount.

[Explanation of symbols]

(1) --Continuous heating furnace, (2) --Vertical roll, (3) --Rough rolling mill, (3a)-Edger, (4) --Rough rolling mill, (4a)-Edger, (5) --Rough rolling mill, (5a)-Edger, (6) --Rough rolling mill, (6a)-Edger, (7) --Finishing rolling mill, (M) --Material,
(B) - coarse bar, (S) - strips, L _R - Roughness bar length,
L _RT --Rough bar tip width compensation length, W ₀ --Standard opening, W
(X)-longitudinal edger opening, ΔW _R --compensation amount, x--
Distance from the end point A of the rough bar tip width compensation length L _RT .

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[Procedure amendment]

[Submission date] April 26, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

FIG. 1 is an explanatory view of rolling equipment and control according to an embodiment of the present invention, in which (a) is a schematic explanatory view of a hot rolling mill line applied, and (b) is an edger opening control pattern. FIG.

Claims (1)

[Claims] 1. A hot rolling method for strips continuously rolled by a hot rolling mill line comprising at least one rough rolling mill having an edger on the inlet side and a finishing rolling mill. Predict the strip width variation that occurs during accelerated rolling in the rolling mill, obtain the compensation amount for the rough bar width on the entry side of the finishing rolling mill from the predicted value for this strip width variation, and then based on this compensation amount. A method for hot strip rolling, characterized in that the opening of the edger of the rough rolling mill is controlled to change the width of the rough bar rolled by the rough rolling mill in the longitudinal direction in accordance with the compensation amount.