JP3341622B2 - Strip width control method in hot rolling line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot rolling line in which a predetermined product width is obtained in consideration of a change in the width of a material to be rolled which occurs from a finishing mill to a winding machine. The present invention relates to a sheet width control method.

[0002]

2. Description of the Related Art Generally, in a hot rolling line for a material to be rolled such as a thin steel sheet, the material to be rolled out of a finishing mill is passed through a cooling device to cool the material to a required temperature and then pinched. It is wound in a coil shape on a winder via a roll. By the way, while the material to be rolled is being wound on the winder, in order to improve the winding shape, the winding speed on the winder is set higher than the material speed on the exit side of the finishing mill, thereby finishing the material. Winding is performed while applying an appropriate tension to the material to be rolled between the rolling mill and the winder.

As described above, it is necessary to always apply the tension from the viewpoint of preventing poor winding, and therefore, the width of the material to be rolled must be reduced in accordance with the magnitude of the tension near both ends of the material to be rolled. Occurs over substantially the entire length excluding. FIG. 6 is a graph showing the amount of narrowing generated in the material to be rolled. The horizontal axis shows the positions in the longitudinal direction from the front end to the rear end of the material to be rolled, and the vertical axis shows the width deviation. As is apparent from this graph, a width deviation occurs from the target value over substantially the entire length except for the vicinity of the front end and the rear end of the material to be rolled.

In order to correct this steady narrowing, the following method has conventionally been adopted. As a control method in the setup stage before rolling, the width due to tension is calculated based on the detected width measured by a width meter arranged on the exit side of the finishing mill and a width meter arranged before the winding machine. This is fed back to the width target value determination device on the rough rolling mill exit side,
There is a method of determining the next target value of the rough rolling mill of the material to be rolled (Japanese Patent Publication No. 5-81325).

[0005] As a dynamic control method during rolling, a driving motor for a pinch roll installed in front of the winding machine is controlled so that a detection value of a width meter arranged in front of the winding machine becomes a target value. A method of controlling the tension of the material to be rolled between the finish rolling mill and the pinch roll to obtain a predetermined width before the winding machine (Japanese Patent Laid-Open No. 58-119411).
No.) has been proposed.

However, both of these methods have problems as described below, and it has been difficult to control the width before the winder to a predetermined target value. That is, in the former case, the temperature of the material to be rolled is cooled from the temperature exceeding the transformation point Ar ₃ to the temperature below the transformation point Ar ₃ between the finishing mill and the winding machine. It is difficult to accurately predict the width variation of the material to be rolled, and therefore it is difficult to separate the width variation due to tension from the width variation during this period. Sufficient width accuracy cannot be obtained even when fed back to the apparatus for determining the target width value on the roughing mill exit side.

In the latter case, the width is controlled to a predetermined value by tension control, but the width of change by the tension control is limited. The method of controlling the width by the tension on the material to be rolled before reaching the pinch roll,
There was a problem that the time constant until the width was changed was long. Since the position where the change width is the largest due to the change in the tension is near the transformation point Ar _{3 of the} material to be rolled, that is, near the finish rolling mill side of the cooling device, the material to be rolled is moved from that position to the width gauge position before the winding machine. And a considerable time delay occurs before the width is measured, and it takes time to control the width before the winder to a predetermined width.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to provide:
As a method of obtaining a predetermined pre-winding machine width, a steady-state width narrowing amount generated between the finishing mill and the winding machine, and a correction amount for absorbing a width fluctuation amount due to a temperature drop are obtained by learning, and the finishing rolling mill is obtained. An object of the present invention is to provide a method of controlling a sheet width in a hot rolling line, wherein a target value of a delivery side width is set.

[0009]

According to a first aspect of the present invention, there is provided a method for controlling a sheet width in a hot rolling line, wherein a material to be rolled through a finishing mill is cooled by a cooling device and then wound on a winder. In the strip width control method in the hot rolling line
A width deviation between the width detected by the width meter arranged before the winding machine and a predetermined width target value before the winding machine, and a width determined by the width meter arranged on the exit side of the finishing mill and a predetermined hot finish. The finish width output target value of the finishing mill is corrected so that the width deviation from the roll output side target value becomes equal.

In the first invention, by making the width deviation on the exit side of the finishing mill equal to the width deviation before the winding machine, the influence of the width fluctuation due to the temperature and tension of the material to be rolled during this is eliminated. By setting the exit width deviation of the finish rolling mill to zero, the width deviation before the winding machine can be reduced to zero.

According to a second aspect of the present invention, there is provided a method for controlling a sheet width in a hot rolling line, wherein a material to be rolled having passed through a finishing mill is cooled by a cooling device and then wound around a winding machine. In the sheet width control method, a width deviation between the width detected by the width meter arranged before the winding machine and a predetermined width target value before the winding machine, and the width detected by the width meter arranged on the exit side of the finishing rolling mill, It is characterized in that a finish rolling mill exit width target value for the next material is determined based on the difference between the two width deviations so that the width deviation from the determined finish rolling mill exit width target value becomes equal.

[0012] In the second invention, the target value of the finish width of the finish rolling mill for the next material is determined based on the deviation between the finish width deviation of the finish rolling machine and the width deviation before the winding machine, so that the subsequent material to be rolled is determined. It is possible to more accurately secure the product width with respect to.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a block diagram showing a configuration of an apparatus for implementing a method of controlling a sheet width in a hot rolling line according to the present invention, where 1 indicates a material to be rolled. The material to be rolled 1 is heated to a predetermined temperature in a heating furnace 2 constituting a hot rolling line, then hot-rolled by a rough rolling mill 3 and a finishing rolling mill 4, cooled by a cooling device 5, and pinch rolled The paper is wound by a winder 7 via a reel 6.

The material to be rolled 1 passes through the above-mentioned hot rolling line and, in the course of passing through the rough rolling mill 3, the finishing mill 4 and the cooling device 6, in other words, the winding machine 7. Each of the width meters 11, 12 arranged on the front side (strictly, the entrance side of the pinch roll 6),
In step 13, the board width is detected. Each width meter 11, 12, 1
Reference numerals 3 denote respective width target value determination devices 21, 22, 23 described later.
The width target value is input and set from
When the board width is detected, a signal corresponding to the width deviation is output. Reference numeral 20 denotes a higher-level computer, which inputs and stores various data such as dimensional specifications and rolling conditions associated with the rolling schedule for each material 1 to be rolled, and sends the data to the respective width target value determination devices 21, 22 and 23. Necessary data is provided.

The width target value determining device 21 determines a rough rolling mill exit width target value Wr at the exit side of the rough rolling mill 3 based on the provided data, and the width target value determining device 22 similarly performs finish rolling. Finishing Mill Exit Width Target Value W at Exit of Mill 4
f, and the width target value determination device 23 similarly determines the pre-winding width target value W _DC , respectively, and the determined rough rolling mill exit width target value Wr is used for the width measurement 11 and the finish rolling. The outboard-side width target value Wf is supplied to the width target value determination device 21 and the width meter 12.

The determination order of the width target values Wr, Wf, W _{DC in} the width target value determination devices 21, 22, 23 is performed in the following order. First, the width target value determination device 23 determines the pre-winder width target value W _DC based on the data from the host computer 20, and uses the determined pre-winder width target value W _DC as the width target value determination device 22 and This is given to the width meter 13 respectively.

Next, the width target value determination device 22 is connected to the host computer 2.
Data from 0, determines the delivery side of the rolling mill width target value Wf finish based on the modified data from the width target value learning correction section 24 to the width target value W _DC and later before the winder, out determined finishing mill The side target value Wf is provided to the width target value determination device 21 and the width meter 12 respectively. And finally, the width target value determination device 21 receives the data from the host computer 20 and the finish-rolling-side output width target value W.
Based on f, a rough rolling mill exit width target value Wr is determined and given to the width gauge 11.

Hereinafter, a process of determining each width target value will be described. a) Determination of the pre-winder width target value W _DC The value required as the pre-winder width of the material to be rolled 1 is the width required as a product at room temperature Tn (for example, 20 ° C.), or the next trimming step. This is the width required when the product is conveyed to the printer (this is referred to as the product width Wp). Therefore, the width target value determination device 23 before the winding machine determines the product width Wp at the normal temperature Tn by the temperature T of the material 1 to be rolled at the installation position of the width gauge 13 before the winding machine.
_The pre-winder width target value W _DC is determined by the following equation (1) as a value obtained by adding the _DC converted width Wp ′ and the width accuracy error Δw predicted to occur in the rolling process to reach the _DC .

W _DC = Wp ′ + Δw = Wp ｛1 + α (T _DC −Tn)｝ + Δw (1) where α is a hot correction coefficient determined based on a linear expansion coefficient (usually a different value for each steel sheet. Is determined on the basis of the actual measurement value).
Is mainly based on the coefficient of linear expansion, and it is possible to accurately determine the pre-winder width target value W _DC required to obtain the product width Wp with relatively high accuracy.

B) Determination of target width Wf on the exit side of the finish rolling mill Acting on the material 1 to be rolled between the finish rolling mill 4 and the winding machine 7
The main width influence element is the temperature of the material 1 to be rolled by the cooling device 5.
And the tension applied to the material 1 during this time.
From, the width variation due to temperature drop is Δw_tempDepending on the tension
The width variation is Δw _tThe width target value determination device 12 is
Determine the finish side output width target value Wf of the finishing mill according to the equation (2).
You. Wf = W_DC+ (Δw_temp+ Δw_t…… (2)

[0021] width change amount generated in the material 1 to be rolled between extending from finish rolling mill 4 to the winder 7 includes a width change amount [Delta] w _t by width change amount [Delta] w _temp and tension due to temperature drop as previously described However, the temperature drop cannot be changed in order to obtain the mechanical characteristics of the material 1 to be rolled, and the tension is also indispensable for stabilizing the winding posture by the winding machine 6, and the change is not possible. Is a disturbance as it is, and it is difficult to predict the width control by the tension control because the effect is difficult to obtain because the difference between steel types is large and the time constant is long.

C) Determination of target width Wr of width on the rough rolling mill side The width-influencing element acting on the material 1 to be rolled between the rough rolling mill and the finishing mill is the width variation Δwf by the finishing mill 4. The width target value determination device 11 determines the roughing mill exit side width target value Wr according to the following equation (3). Wr = Wf + Δw _f (3)

The present inventors have conducted experiments and studies to accurately predict the width variation between the finishing mill 4 and the winder 7 as described above. Width target value W
A method has been developed for setting the finish-roller exit width target value Wf so that _DC can be controlled to a predetermined product width Wp. This is because when the target material 1 is actually rolled assuming that the width target values Wr, Wf, and W _DC are set in the width meters 11, 12, and 13 before the material 1 is rolled, the width deviation from the width meter 12 is obtained. [Delta] w _ef is also when the width gauge 13 width deviation [Delta] w _EDC from is output to modify the delivery side of the rolling mill width target value Wf finish so that both the width deviation is equal, mill finish this correction value for the next material by performing the learning correction control to the delivery side width target value width change amount due to width variation amount [Delta] w _temp + tension with temperature drop between reaching the front side of the winder 6 from the delivery side of the finishing mill 4 [Delta] w _t Can be absorbed.

Hereinafter, the contents of the learning correction control will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a calculation process of the width target value learning correction unit on the exit side of the finishing mill. Winder previous width target value decision unit 23 determines the winder before width target value W _DC based on the data supplied from the host computer 20 as previously described, the width target on the delivery side of the rolling mill finishing this Value determination device 22
And to the width gauge 13 before the winding machine. The target width determining device 22 on the exit side of the finishing mill determines the output width target value Wf of the finishing mill on the basis of the data given from the host computer 20 and the target width W _DC before the winding machine. Is given to the width gauge 12 on the exit side of the finishing mill, and the initial settings for the width gauges 12 and 13 are made.

The actual rolling of the material to be rolled 1 is performed,
When finishing mill delivery side in the width rolling mill delivery side width deviation [Delta] w _ef finishing a total of 12 which arranged are also the width gauge 13 arranged before the winding machine and winder before width deviation [Delta] w _EDC is output, these Are given to the width target value learning correction section 24 for the finish side output width target value Wf.

The width target value learning correction unit 24 calculates the width deviation Δw _ef from the width meter 12 on the exit side of the finishing mill and the width deviation Δw _ef before the winding machine from the width meter 13 before the winding machine. _eDc , respectively, and based on these, the forgetting factor G previously set corresponding to the hot rolling equipment, and the learning correction value Δw _FBO previously used under the same conditions and fetched from the learning correction table 25, the following ( 4) New learning correction value Δw according to equation
_FB is calculated and given to the learning correction table 25 to replace the previous learning correction value Δw _FBO and to the width target value determination device 22 on the exit side of the finishing mill. _{Δw FB = Δw FBO + G ·} {(Δw ef -Δw eDC) -Δw FBO} ... (4)

The learning correction table 25 stores the material, the sheet width, the sheet thickness, the cooling pattern of the cooling device 5, the cooling pattern of the cooling device 5, and the rolling material 1 from the final stand of the finishing mill 5 to the winding machine 7. The learning correction values in the past are stored by stratification for each applied tension, and the learning correction values are stored in the columns of the table corresponding to the material, plate width, plate thickness, cooling pattern and tension of the material to be rolled currently being rolled. When the value Δw _FBO is read and a new learning correction value Δw _FB is calculated, the corresponding past learning correction value Δw _FBO is rewritten to Δw _FB .

The forgetting factor is a numerical value indicating how much the previous learning correction value and the learning correction value obtained this time are reflected in the next value, and it is necessary to consider the previous learning correction value at all. If the learning correction value obtained this time is used as the next learning correction value, the value is set to "1". Also, the learning correction value obtained this time is not considered at all, and the previous learning correction value is used. Is set to a value of "0" when the next learning correction value is set, and an intermediate value between 0 and 1 depending on the degree of the intermediate value between them.

The forgetting factor is appropriately set in the width target value learning correction unit 24 before or during the operation in accordance with the past or current characteristics of the hot rolling line or the like, and is input. I have. The finish target width-determining device 22 on the exit side of the finishing mill determines the finish width target width value Wfn for the next workpiece 1 in accordance with the following equation (5). _{Wfn = Wf + Δw FB ... (} 5) By performing such learning correction control, and the width deviation finishing mill exit side [Delta] w _ef, as well as equal to the width difference [Delta] w _EDC before the winder, out finishing mill by performing control to zero by the width control up easy finishing mill 4 outlet side of the relatively wide control width deviation [Delta] w _ef side, winder previous width deviation [Delta] w _EDC
Can also be set to zero.

Moreover, even if the exit width deviation of the finishing mill and the width deviation before the winding machine cannot be made equal during the setup control,
During rolling of the material 1 to be rolled, the target value of the output width of the finishing mill is changed so that the difference between the output width deviation of the finishing mill and the width deviation before the winding machine becomes zero. The width deviation before de-grip can be made zero.

FIG. 3 is a graph showing the width control result when the method of the present invention is applied. FIG. 3 (a) shows the learning correction value (mm) on the vertical axis, and FIG. (Mm)
FIG. 3 (c) shows the exit width deviation of the finishing mill (mm).
, And the horizontal axis indicates the number of rolls. Now, with respect to the first run of the material to be rolled, the finishing mill delivery side width meter 12, finishing mill delivery side width deviation [Delta] w _ef occurs, also winding machine front width in the width gauge 13 before the winder deviation [Delta] w _EDC occurs, the difference therebetween _{Δw ef} -Δw eDc Figure 3
It was +3 mm as shown by (b).

As a result, in the width target value learning correction section 24, the learning correction value Δw _FB is calculated as Δw _FB = 0 + 0.3 × (−3−0) = − 0.9 mm (FIG. 3A) reference). In addition, the finish width mill exit side width target value determination device 22 calculates the finish rolling mill exit side width target value Wfn for the second material to be rolled according to equation (5) by-
Corrected by 0.9 mm, the second rolled material was rolled (see FIG. 3 (c)).

[0033] Repeat the same process, three subsequent when the rolled material is rolled in the as finishing mill delivery side width deviation [Delta] w _ef and winder before width deviation [Delta] w _EDC shown in FIG. 3 (b) Is substantially zero, and the learning correction value Δw _FB also stably changes to approximately −2 mm as shown in FIG. When this is compared with the rolling results in the case where the present invention is not applied as shown in FIG. 4, when the method of the present invention is not applied, the difference between the exit width deviation on the finishing mill and the width deviation before the winding machine is large. Moreover, it can be seen that the fluctuation of the difference between them is not large and stable.

In FIG. 4, the cooling pattern by the cooling device is set and controlled for the fourth material to be rolled, and the tension is set and controlled for the fifth material to be rolled by keeping the cooling pattern constant. In each case, it can be seen that variations occur due to control errors.
In particular, in the fourth rolled material, the width deviation before the winding machine is large even though the width deviation on the exit side of the finishing mill can be controlled to almost zero, and it is not possible to accurately predict the width fluctuation. Suggest that.

FIG. 5 is a graph showing a comparison result between the case where the method of the present invention is applied and the case where the method is not applied. The difference between the exit side width deviation of the finishing mill and the width deviation before the winding machine is shown. The width deviation before de-grinding is shown. As is clear from this, when the present invention is not applied (in the case of OFF), the width variation portion of the material to be rolled from the finish rolling mill exit side to the front of the winding machine cannot be accurately predicted. The width deviation before the winding machine is large because the exit width of the finishing mill is set and controlled so that the front width does not fall below the product width. On the other hand, when the method of the present invention is applied, the width deviation before the winding machine is only about 1.0 mm as compared with the case where the method is not applied, and the difference between the width deviation before the finishing mill and the width deviation before the winding machine is also substantially smaller. It can be seen that all of them can be reduced by 1.0 mm.

[0036]

As described above, according to the method of the present invention, the finish width output side target value is corrected and controlled so that the finish side output width deviation is equal to the width deviation before the winding machine. In the end, the width deviation on the finish rolling mill exit side can be eliminated by the width control until reaching the finish rolling mill exit side, so that the width deviation before the winder can be eliminated at the same time, or can be significantly reduced. Thus, an excellent effect of reducing the crop amount of the material and reducing the cost is achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an apparatus for implementing a method of the present invention.

FIG. 2 is an explanatory diagram showing a calculation process of a width target value learning correction unit on the exit side of a finishing mill in the apparatus shown in FIG. 1;

FIG. 3 is a graph showing a result of width control when the method of the present invention is applied.

FIG. 4 is a graph showing test results when the method of the present invention was not applied.

FIG. 5 is a graph showing comparison results when the method of the present invention is applied and when it is not applied.

FIG. 6 is a graph showing a narrowing amount generated in a material to be rolled.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolled material 2 Heating furnace 3 Rough rolling mill 4 Finishing rolling mill 5 Cooling device 6 Pinch roll 7 Winding machine 11, 12, 13, Width meter 20 Host computer 21, 22, 23 Width target value determination device 24 Width target value Learning correction section 25 Learning correction table

Continued on the front page (72) Inventor Ryo Kurimoto 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 37/00 -37/78

Claims (2)

(57) [Claims] 1. A method for controlling a sheet width in a hot rolling line in which a material to be rolled after passing through a finishing mill is cooled by a cooling device and then wound around a winding machine, wherein the width arranged before the winding machine is provided. Width deviation between the width detected by the gauge and the predetermined width target value before the winding machine, and the width detected by the width meter disposed on the exit side of the finishing mill and the predetermined width target value on the exit side of the hot finishing mill. A method for controlling a sheet width in a hot rolling line, wherein the target value on the exit side width of the finishing mill is corrected so that the width deviation becomes equal. 2. A method for controlling a sheet width in a hot rolling line in which a material to be rolled after passing through a finishing mill is cooled by a cooling device and then wound on a winder, the width meter arranged before the winder. The width deviation between the detected width and the predetermined width target value before the winding machine, and the width deviation between the detection width and the predetermined finishing roll output side target value detected by the width meter arranged on the finishing roll output side. A width control method for a hot rolling line, comprising: determining a target width on the exit side of a finishing mill for a next material based on a difference between the width deviations so that the widths are equal.