JP2002066635A - Method for manufacturing hot rolled steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce fluctuations of plate with among coils and inside coils which a hot rolled steel strip may have, without impairing the pickling performance or giving bad effects on accuracy of the wall thickness after the cold rolling, by controlling the plate width using a tension leveler provided in the pickling process, when a hot rolled steel strip is manufactured through the pickling process having the tension leveler in the inlet side of the pickling bath and the hot rolling process. SOLUTION: The hot rolled steel strips 2 is manufactured through the pickling process having the tension leveler 8 in the inlet side of the pickling bath 11 and the hot rolling process. In this case, the plate width distribution in the longitudinal direction of the steel strip after rolling in the hot rolling process is continuously measured. And in accordance with the difference between a minimum width or a typical width of the steel strip specified in the subsequent pickling process based on the plate width distribution in the steel strip longitudinal direction after rolling continuously measured in the hot rolling process and a target plate width in the hot rolling process, an extensional rate is corrected from the predetermined value when the steel strip passes the tension leveler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hot-rolled steel strip produced through a hot rolling step and a pickling step having a tension leveler on the entrance side of a pickling tank, and in particular, to the width accuracy of a steel strip. The present invention relates to a method for manufacturing a hot-rolled steel strip which can reduce trim debris in a trimming step by improving the quality.

[0002]

2. Description of the Related Art Steel strips produced through a hot rolling process are:
It passes through a pickling line in order to remove the oxide scale generated on its surface. As a general scale removing method, as shown in FIG. 1, a hot-rolled steel strip 2 is subjected to repeated bending deformation under tension in a tension leveler 8 to cause cracks in the oxide scale on the surface. Thereafter, when the steel strip is passed through a pickling solution such as hydrochloric acid or sulfuric acid in the pickling tank 11, the pickling solution penetrates into cracks formed on the surface, so that the chemical scale removing effect can be enhanced. .

[0003] Such a pickling line is provided with a trimming device 12 on the downstream side of a pickling tank 11, and the steel strip is adjusted to a predetermined plate width to obtain a product. Also, when the steel strip is processed through a cold rolling process, an annealing process, a temper rolling process, and a recoil line, the trimming is not performed in the pickling line, but is performed in the recoil line after the temper rolling process. The width may be adjusted to a predetermined value. The pickling process and the cold rolling process may be continuous,
In this case, a trimming device 12 is generally installed between the pickling tank 11 and the cold rolling mill 17 as shown in FIG.

[0004] When a continuous annealing facility is used as an annealing step, the functions of the annealing step, the temper rolling step, and the recoil line are often provided in the continuous annealing facility. Is generally adjusted to a predetermined plate width by using a trimming device arranged downstream of the apparatus.

[0005] In any case, the steel strip which becomes a product after passing through the pickling line is usually adjusted to a predetermined sheet width through at least one trimming step. Reducing the amount of trim waste generated at this time has an important meaning in improving the yield.

Incidentally, when trimming is performed in the pickling line, the target plate width Wh in hot rolling is determined based on the following equation (1).

Wh = Wp + ΔWt + ΔWd + ΔWs (1) where Wp: strip width after trimming ΔWt: minimum trim margin required for trimming ΔWd: width reduction in tension leveler ΔWs: average value of margin in consideration of variation in hot-rolled width The minimum trim margin ΔWt necessary for trimming is a cut margin necessary for stably trimming while preventing operation trouble, and usually requires about 6 to 10 mm. Further, in the tension leveler, an elongation rate of at least 0.5% or more is given, and the sheet width decreases with elongation of the steel strip. Therefore, the width shrinkage ΔWd in the tension leveler needs to be added to the target sheet width in hot rolling with the width shrinkage as a margin. Furthermore, the variation in the sheet width within the coil of the hot rolled steel strip or between the coils,
Since it cannot be completely eliminated, it is necessary to add an average value (margin allowance) ΔWs of the margin in consideration of the variation.

The variation of the sheet width between the coils in the normal hot rolling process is about 1.2 to 2.0 mm in standard deviation σ, and even if there is such a variation, a minimum cutting allowance is required in the trimming process. In order to have it, it is necessary to set 3.6 to 6.0 mm corresponding to 3σ of the variation as ΔWs. FIG. 2 shows such a concept. In FIG. 2, a hatched portion indicates a range of variation of a hot-rolled width (HOT width), and an actual plate width of the coil is any width within the hatched range. Also, the error of the hot-rolled width = the actual sheet width−Wh, and the actual value of the surplus width = ΔW
s + the error of the hot rolling width, the average value of the excess width = ΔWs, the trim allowance = ΔWt + ΔWs + the error of the hot rolling width, and the average value of the trim allowance = ΔWt + ΔWs. In particular, the main cause of the average value ΔWs of the margin in consideration of the variation in the sheet width of the hot-rolled steel strip is as follows.
The average of the trim charges has to be large.

On the other hand, when trimming is not performed in the pickling line but is performed after a cold rolling step, an annealing step, and a temper rolling step, cold rolling, It is necessary to add a margin in consideration of the necking amount of the sheet width in the annealing step and the temper rolling step and the variation thereof.

[0010] As a conventional technique for reducing trim debris in the trimming process as described above and improving the yield, there is a method disclosed in Japanese Patent Publication No. 24916/1990. This is a method in which the steel strip width is continuously measured at the entry side of the tension leveler provided in the pickling line, and the elongation rate in the tension leveler is controlled according to the difference between the measured value and the target value of the sheet width. is there.

[0011]

When the invention disclosed in Japanese Patent Publication No. 24916/1990 is implemented as a conventional technique, the following problems occur. Generally, the width of a hot-rolled steel strip fluctuates in the longitudinal direction. For example, in a hot rolling process, an excessive tension is generated at the moment when the steel strip is taken up by a winder, and a local narrowing caused by the tension occurs. May occur. In addition, there are several causes for such local shrinkage, and it is difficult to predict in advance at which position in the hot-rolled coil how much shrinkage exists.

According to the method disclosed in Japanese Patent Publication No. 24916/1990, even with such a hot-rolled steel strip having a locally widened portion, a plate disposed on the entry side of the tension leveler in the pickling step. Until it passes the width meter, it cannot be detected. Therefore, if the fluctuation of the sheet width in the longitudinal direction of the steel strip is gentle, it is possible to adjust the elongation rate of the tension leveler, but it is detected for a steel strip having a locally large width reduction. However, since there is not enough time to adjust the elongation rate of the tension leveler, there is a problem that effective width control cannot be performed.

In other words, when the width of the plate is detected locally by the width meter while the width of the plate is controlled by giving an almost constant elongation rate by the tension leveler, the tension leveler is not used. Although it is necessary to lower the elongation rate and reduce the amount of width reduction in the tension leveler, by passing through the tension leveler without sufficiently reducing the elongation rate, the plate width after the pickling process is locally smaller than the target. Will also be narrow. Such a steel strip narrower than the target sheet width has a poor width and does not satisfy the specifications as a product.

On the other hand, when the control gain is set high in order to enhance the response of the elongation rate control by the tension leveler, an excessive change in the elongation rate target value is locally applied to a large width narrowing portion. And it becomes a factor that hinders control stability. Furthermore, in the tension leveler,
When the elongation rate is changed in the longitudinal direction of the steel strip, a change in the sheet thickness occurs together with the sheet width. Particularly with respect to the thickness variation in the longitudinal direction, if the variation frequency is high, the base material thickness in the subsequent cold rolling process fluctuates at a high frequency, and the thickness accuracy after cold rolling is reduced. Has a negative effect. Therefore, from the viewpoint of preventing the plate thickness fluctuation, the responsiveness of the extension rate control of the tension leveler must be reduced to some extent.

Further, the target strip width of the hot-rolled steel strip has an average value (a margin allowance) ΔWs in consideration of variations between coils.
3.6 to 6.0 mm, and a local width variation of about 2 to 5 mm may occur even in the coil. Therefore, only by the method of adjusting the elongation rate of the tension leveler described in Japanese Patent Publication No. 24916/1990, it is natural to make the plate width of all the hot-rolled steel strips coincide with the target value over the entire length in the longitudinal direction. There is a limit.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and the means are as follows. (1) In producing a hot-rolled steel strip through a hot rolling step and a pickling step having a tension leveler on the entrance side of a pickling tank, the strip width distribution in the longitudinal direction of the strip after rolling in the hot rolling step is determined. Measured continuously, in the pickling process, the minimum width or representative width of the steel strip specified based on the strip width distribution in the longitudinal direction of the strip after rolling continuously measured in the hot rolling step and the hot work A method for manufacturing a hot-rolled steel strip, wherein an elongation rate when the steel strip passes through the tension leveler is corrected from a preset value according to a difference from a target strip width in a rolling step.

(2) In producing a hot-rolled steel strip through a hot-rolling step and a pickling step having a tension leveler on the entrance side of the pickling tank, a plate in the longitudinal direction of the steel strip after rolling in the hot-rolling step The width distribution is continuously measured, in the pickling process, according to the difference between the strip width distribution in the longitudinal direction of the strip after rolling continuously measured in the hot rolling process and the target plate width in hot rolling. And correcting the intermesh when the position of the steel strip passes through the tension leveler from a preset value while keeping the elongation rate constant.

(3) In producing a hot-rolled steel strip through a hot rolling step and a pickling step having a tension leveler on the entry side of a pickling tank, the steel strip is produced on the entry side of the tension leveler in the pickling step. The continuous width distribution in the longitudinal direction of the steel strip is measured continuously, and the elongation rate is constant according to the difference between the measured continuous width distribution of the steel strip and the target width in hot rolling. A method of manufacturing a hot-rolled steel strip, wherein the intermesh when the position of the steel strip passes through the tension leveler is corrected from a preset value while maintaining the above value.

(4) In producing a hot-rolled steel strip through a hot rolling step and a pickling step having a tension leveler on the entrance side of a pickling tank, a plate in the longitudinal direction of the steel strip after rolling in the hot rolling step. The width distribution is measured continuously, in the pickling process, the minimum width or the representative width of the steel strip specified based on the strip width distribution in the longitudinal direction of the strip after rolling continuously measured in the hot rolling step. And, according to the difference between the target sheet width in the hot rolling step, while correcting the elongation rate when the steel strip passes through the tension leveler from a preset value, the elongation rate was corrected as described above. While maintaining the elongation, the strip width distribution in the steel strip longitudinal direction after rolling continuously measured in the hot rolling step, and the steel strip longitudinal direction of the minimum width or the representative width of the steel strip specified above. Corresponding to the continuous width deviation of the strip passes through the tension leveler Method for producing a hot rolled strip, characterized in that to correct the intermesh from a preset value.

(5) In producing a hot-rolled steel strip through a hot rolling step and a pickling step having a tension leveler on the entrance side of a pickling tank, a plate in the longitudinal direction of the steel strip after rolling in the hot rolling step The width distribution is measured continuously, in the pickling process, the minimum width or the representative width of the steel strip specified based on the strip width distribution in the longitudinal direction of the strip after rolling continuously measured in the hot rolling step. And, according to the difference between the target sheet width in the hot rolling step, the elongation rate when the steel strip passes through the tension leveler is corrected from a predetermined value, and further, the steel strip is provided on the entry side of the tension leveler. Continuously measure the strip width distribution in the longitudinal direction of the strip, further determine the deviation from the target strip width in hot rolling over the steel strip longitudinal direction, according to the determined continuous width deviation in the longitudinal direction,
A method for manufacturing a hot-rolled steel strip, wherein an intermesh when the position of the steel strip passes through a tension leveler is corrected from a preset value while maintaining the stretch rate at the corrected stretch rate.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the means (1) of the present invention, the width of a steel strip in the longitudinal direction is continuously measured by using a width gauge upstream of a winder in a hot rolling process. . Using a data processing device or the like, the minimum or representative value of the plate width in the coil is specified from the measured data. The minimum value of the plate width indicates the plate width at the position where the plate width is the smallest in the coil, including the region where local necking occurs in the coil. This is related to the fact that at the time of performing the above-mentioned trimming, it is necessary to secure the minimum trim allowance at all positions in the longitudinal direction of the steel strip, and based on this value, the average strip width of the steel strip is used. Is desirably controlled. However, a value representative of the plate width of the coil, such as an average width in the coil, may be used as a reference, and the plate width specified above is used to determine the variation in the plate width between the coils. The width used as an index.

In the present invention, the representative plate width of the single coil specified above is compared with the target plate width in the hot rolling step, and the representative plate width and the target width Wh (= Wp + Δ) are compared.
Wt + ΔWd + ΔWs) (representative plate width−
When the target width is increased, the preset expansion rate is modified to increase the expansion rate in the following manner.

The representative plate width is Wp + ΔWt + ΔWd +
If it is smaller than ΔWs and slightly larger than Wp + ΔWt + ΔWd, the elongation rate is not changed, and the representative plate width is
If it is larger than this, the correction is made so as to increase the preset expansion rate accordingly. In this case, as the relative difference increases, the set value of the elongation rate to be corrected may be gradually increased, or may be increased stepwise as in the embodiment.

For a coil having a relatively large width difference, the set value of the extension rate of the tension leveler in the pickling line is set to be larger than a normal extension rate set in advance so that the coil can be used. Can be reduced, and the trim allowance can be reduced.

The steel strip width after hot rolling is Wp + ΔWt + ΔW
If it is smaller than d, it is not possible to secure the minimum trim margin ΔWt required for trimming at the preset elongation rate. In this case, in order to secure the minimum trim margin ΔWt, it is theoretically possible to lower the preset elongation rate. However, the target sheet width Wh in the hot rolling is added to the width elongation ΔWd at a preset elongation rate in the tension leveler.
The average width ΔWs of the extra width in consideration of the sheet width variation in the coil and between the coils in the hot rolling of the hot-rolled steel strip, the strip width after the hot rolling becomes Wp + ΔWt + ΔWd.
There is almost no narrowing. For this reason, in the present invention, no correction is made to lower the preset elongation rate. In addition, since the elongation rate of the tension leveler is set in advance to a value necessary to secure the pickling property in the pickling tank, there is a problem that the efficiency of pickling is reduced by reducing the elongation rate. Absent.

Incidentally, the means (1) of the present invention does not assume that the elongation rate of the tension leveler is changed in the coil as in the prior art. Therefore, high responsiveness regarding the elongation rate control is not required, and the thickness variation in the coil is not increased, so that the thickness accuracy in the cold rolling process is not adversely affected. In addition, since the longitudinal width distribution of the steel strip to be controlled is detected in advance over its entire length, and the elongation rate is set using the minimum width or the representative width, a locally large width-reducing portion may be formed. Even in the case of passing through the tension leveler, it is possible to set such that the plate width of that portion is not too narrow.

Next, the operation of the means (2) of the present invention will be described. This means that the sheet width in the hot rolling step is continuously measured in the longitudinal direction, and when the coil passes through the tension leveler of the pickling line, the measured value is used as the target sheet width in the hot rolling step. In this method, the intermesh of the tension leveler is adjusted in accordance with the timing at which a portion relatively wider than the target passes through the tension leveler. Specifically, the intermesh is set to be smaller than a preset normal value in accordance with the timing at which the portion passes through the tension leveler. However, the present invention does not change the elongation rate as in the prior art, but changes the balance between the intermesh for generating the elongation rate and the tension while keeping the set value of the elongation rate constant. This is the concept of (2). In this case, even at the same elongation rate, the elongation strain mainly based on the tension further increases, the necking of the sheet width becomes remarkable, and the trim margin can be reduced.

By the way, even at the same elongation rate, depending on the balance between the applied tension and the intermesh,
The phenomenon in which the deformation behavior in the width direction of the sheet changes will be described.
In general, in tension levelers, setting the intermesh to a relatively small value and applying a large tension to obtain a constant elongation rate, or setting the intermesh to a large value and bending the steel strip By increasing the curvature, a similar elongation ratio may be obtained even with a relatively low tension. For example, giving an elongation to a steel strip by simple tensile deformation is an extreme example of the former. At this time, it has been experimentally confirmed that even when the same elongation rate is given, the constraint on the deformation in the plate width direction is different depending on the balance between the intermesh and the tension. FIG. 3 shows an example of the experimental result. Even if the elongation rate is the same, when the width of the neck (the amount of necking) is to be increased, it is necessary to reduce the intermesh and increase the tension. It is effective. In addition, in FIG. 3, I / M is an intermesh.

The means (2) of the present invention utilizes such a characteristic, and the intermeshing is performed while keeping the target value of the elongation rate constant with respect to the fluctuation of the strip width in the longitudinal direction of the steel strip. Only the amount of necking is controlled by changing only the width. This is different from the conventional technique, in which the control target value of the elongation rate control is changed positively in the coil, but the target value of the elongation rate control is kept constant and only the set value of the intermesh is changed. Therefore, the influence of destabilizing the elongation rate control is small. Further, since the elongation rate is kept constant, a large thickness variation does not occur as in the prior art, and the thickness accuracy in the cold rolling process is not adversely affected.

In the means (2), the strip width in the longitudinal direction of the steel strip is continuously measured in the hot rolling step. However, in the means (3) of the present invention, the steel strip is located upstream of the tension leveler of the pickling line. The plate width in the longitudinal direction is continuously measured, and the intermesh in the tension leveler is adjusted according to the difference between the measured value and the target plate width in hot rolling. This uses a method of continuously measuring the width of the hot-rolled steel strip on the entry side of the tension leveler, as in the prior art.
Similar to the means (2) of the present invention, only the intermesh is changed while the preset elongation rate is kept constant, and the same effect as described above can be obtained.

When the means (2) and (3) of the present invention are compared, the following differences are observed. In the means (2) of the present invention, a method of measuring the sheet width over the entire length in the hot rolling step is used, and a sheet width gauge which is usually used for controlling the sheet width in the hot rolling step may be used.
On the other hand, in the means (3) of the present invention, since a width gauge is not generally provided on the entrance side of the tension leveler, a width gauge must be newly installed in order to carry out the present invention. On the other hand, in the means (2) of the present invention, the control gain of the intermesh adjustment corresponding to the local width variation can be set in advance by measuring the sheet width over the entire length of the coil in the hot rolling step. it can. However, if there is an intermediate process such as passing a skin pass process before loading the hot-rolled steel strip into the pickling line, the sheet width in the pickling line may be reversed, such as the tip and rear ends of the coil being reversed. Complicated data processing is required to specify the distribution. On the other hand, in the means (3) of the present invention, such advantages and disadvantages are reversed.

Further, the means (4) of the present invention aims to obtain a greater effect by combining the means (1) and (2). That is, in the hot rolling step, the strip width in the steel strip longitudinal direction is continuously measured, and the minimum or representative value of the strip width in the coil is calculated. When the coil passes through the tension leveler of the pickling line, the tension leveler is adjusted according to the difference between the calculated width and the target width in hot rolling in order to adjust the width of each coil. Is corrected from the preset elongation rate. At the same time, the deviation between the continuous measurement value of the sheet width and the minimum value or the representative value is calculated while keeping the extension ratio at the fixed extension ratio corrected as described above, and the tension leveler interface is calculated in accordance with the deviation. Modify the mesh from normal settings.

In the means (4) of the present invention, the extension rate of the tension leveler is changed according to the average plate width for each coil, and the extension rate is kept constant with respect to fluctuations in the coil. However, since different plate width control means for changing only the intermesh are combined, a greater effect can be obtained when an attempt is made to reduce the trim margin in a portion where the plate width is wide.

Further, in the means (5) of the present invention, the steel strip is used for both the strip width meter upstream of the winder in the hot rolling step and the strip width meter upstream of the tension leveler of the pickling line. The effect obtained by the means (4) is intended to be more reliably exhibited by continuously measuring the plate width in the longitudinal direction.

That is, in the means (4), according to the difference between the measured value of the strip width distribution in the longitudinal direction of the steel strip measured in the hot rolling step and the target strip width in the hot rolling, an intermesh in the tension leveler is used. Was corrected from the normal setting value,
In the means (5), instead of this, according to the difference between the measured value of the strip width distribution in the steel strip longitudinal direction measured upstream of the tension leveler of the pickling line and the target strip width in hot rolling. ,
Correct the intermesh in the tension leveler from the normal setting value. If there is an intermediate step such as passing through a skin pass step before loading the hot-rolled steel strip into the pickling line, in the means (4), the pickling line such as the tip and rear ends of the coil being reversed. Although complicated data processing is required to specify the sheet width distribution in the above, the means (5) does not require such complicated data processing, and the same effect as the means (4) can be more simply and reliably achieved. Can be expressed.

Hereinafter, embodiments of the present invention will be further described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the arrangement of the main components of a pickling line (pickling process) used for describing an embodiment of the present invention. The steel strip wound up in the hot rolling step is charged to a pickling line after being cooled to about room temperature. The steel strip (hot rolled steel strip) 2 paid out from the pay-off reel 1 is cut at the leading and trailing end by a shearing machine 4 and connected to a subsequent steel strip 2 at a welding machine 5. The tension leveler 8 used in the embodiment of the present invention includes:
Tension is applied by the bridle rolls 9 and 10, and the belt of the tension leveler 8 undergoes bending deformation, thereby causing elongation of the steel strip. Due to the effect of the elongation, cracks are generated on the scale on the surface of the steel strip, and the subsequent pickling in the pickling tank 11 is improved. further,
A trimming device 12 for adjusting the width of the steel strip to a predetermined value is disposed downstream.

The production line shown in FIG. 1 is a facility in which the pickling process and the cold rolling process are continuous, and is cut into a predetermined coil length by a shearing machine 14 and a coiler (tension reel) 15. When winding and without cutting
In some cases, the steel sheet is cold-rolled to a predetermined thickness by a cold rolling mill 17 that is continuously arranged downstream, and then wound up by a coiler 18.

As a normal operation method, when cold rolling is performed continuously after pickling, the trimming apparatus 12 is rarely used, and the steel strip after cold rolling is subjected to annealing and temper rolling. After that, trimming is often performed to a predetermined plate width. On the other hand, when winding is performed by the coiler 15 without performing cold rolling after the pickling, the trimming device 12 is used to obtain a predetermined sheet width. In any case, after the steel strip 2 passing through the pickling line (pickling process) passes through the tension leveler 8 and before it is shipped as a product, the steel strip 2 is subjected to any one of the trimming devices to remove the width of the strip. Must be adjusted to a predetermined value.

FIG. 4 is a first diagram showing an example of the arrangement of the main components of the tension leveler provided in the pickling step in order to carry out the present invention. In the means (1) of the present invention, the strip width in the longitudinal direction of the steel strip is continuously measured in the hot rolling step. The measurement result is sent to the pickling process together with the coil number and the like. The measurement data sent from the hot rolling process is stored in the data processing device 25. In the data processing device 25, from the plate width distribution in the longitudinal direction of the coil,
The width of the narrowest part in the coil is specified as the minimum width. However, the average width in the coil and other plate widths representing the coil may be specified. The minimum width or the representative width obtained in this way is compared with the target sheet width in the hot rolling step, and an increase ΔE of the elongation rate in the tension leveler is set according to the magnitude of the deviation, and the tension leveler is set. It is sent to the control device 26.

The tension leveler control device 26 gives a command to the intermesh control device 27 to set an intermesh set in advance for each steel type and size according to the timing at which the steel strip reaches the tension leveler. . At the same time, the normal elongation rate setting value,
The extension rate control is performed with the extension rate to which ΔE has been added set as the target extension rate.

The tension leveler control device 26 gives a peripheral speed difference between the bridle roll 20 on the entrance side and the bridle roll 24 on the exit side corresponding to the target elongation. When the target elongation rate is corrected, a peripheral speed difference corresponding to the correction amount is given to the bridle roll 20 and the outgoing bridle roll 24. The line tension is automatically corrected in accordance with the given peripheral speed difference and intermesh.

On the other hand, in the means (2) of the present invention, the strip width in the longitudinal direction of the steel strip is continuously measured in the hot rolling step. The measurement result is composed of measured values of the position in the longitudinal direction of the coil and the plate width, and is sent to the pickling step together with the coil number and the like. The measurement data sent from the hot rolling process is stored in the data processing device 25. In the data processing device 25, the measured value of the plate width in the longitudinal direction is compared with the target plate width in the hot rolling process, and the intermesh change amount ΔI in the tension leveler according to the magnitude of the deviation is calculated in the longitudinal direction of the steel strip. The setting is made in accordance with the position, and a command is given to the tension leveler control device 26.

In the tension leveler control device 26, the elongation rate is controlled in accordance with the timing at which the coil reaches the tension leveler, using the set value of the elongation rate preset for each steel type and size as the target elongation rate. . At the same time, a command is given to the intermesh control device 27 so as to set the normal intermesh amount.

Further, while the coil is passing through the tension leveler, the tension leveler control device 26
In the pickling process, the advance amount of the steel strip is calculated in accordance with the line speed, and the intermesh change amount ΔI corresponding to the variation in the width of the strip in the longitudinal direction is added to the normal set value, and the intermesh control device 27 Send to The intermesh control device 27 keeps the target elongation rate constant while maintaining the target elongation rate so as to match the instructed intermesh.
Change the position of.

FIG. 5 is a second diagram showing an example of the arrangement of the main components of the tension leveler provided in the pickling step in order to carry out the present invention. The means (3) of the present invention will be described with reference to FIG. Here, the width distribution of the hot-rolled steel strip in the longitudinal direction of the coil is measured using the width meter 28 installed on the entry side of the tension leveler. The measurement data is sequentially sent to the data processing device 25. In the data processing device 25, the measured value of the plate width in the longitudinal direction is compared with the target plate width in the hot rolling process, and the intermesh change amount ΔI of the tension leveler according to the deviation is instructed to the tension leveler control device 26. give.

The tension leveler controller 26 predicts the time from when the steel strip passes through the width gauge 28 to when it reaches the tension roll 21 of the tension leveler, and the timing at which the strip width measurement position reaches the tension leveler. Then, a value obtained by adding the intermesh change amount ΔI to the normal intermesh set value is sent to the intermesh control device 27. The intermesh control device 27 includes:
The position of the elongating roll 22 is changed so as to match the instructed intermesh.

Subsequently, in the means (4) of the present invention, in the apparatus configuration shown in FIG. 4, the data of the sheet width measured in the hot rolling step is sent to the pickling step together with the coil number and the like. The measurement data sent from the hot rolling process is stored in the data processing device 25. In the data processing device 25, the width of the narrowest part in the coil is specified as the minimum width from the width distribution of the coil in the longitudinal direction. However, a representative width such as an average width in the coil may be specified. The minimum width or the representative width obtained in this way is compared with a target plate width in the hot rolling step, and an increase ΔE of the elongation rate in the tension leveler is set according to the magnitude of the deviation. At the same time, the measured value of the plate width in the longitudinal direction is compared with the minimum value or the representative value of the plate width over the entire length in the longitudinal direction, and the intermesh change amount ΔI
Is set corresponding to the longitudinal position of the steel strip.

These data are sent to the tension leveler control device 26, and the intermesh control device is set so that the intermesh set in advance for each steel type and size is set in accordance with the timing at which the coil reaches the tension leveler. 27 is given a command. at the same time,
The extension rate control is performed with the extension rate obtained by adding ΔE to the normal extension rate set value as the target extension rate. Further, while the coil is passing through the tension leveler, the tension leveler control device 26 calculates the amount of progress of the steel strip in accordance with the line speed of the pickling process, and adjusts the intermesh corresponding to the plate width variation in the longitudinal direction. Adding the change amount ΔI to the normal set value,
It is continuously sent to the intermesh controller 27. The intermesh control device 27 changes the position of the extension roll 22 so as to match the instructed intermesh.

In the means (5) of the present invention, in the apparatus configuration shown in FIG. 5, the data of the sheet width in the coil longitudinal direction measured in the hot rolling step is sent to the pickling step together with the coil number and the like. Are stored in the data processing device 25. In addition, the width distribution of the hot-rolled steel strip in the longitudinal direction of the coil is measured using the width gauge 28 installed on the entry side of the tension leveler. The measurement data is sequentially sent to the data processing device 25.

The data processor 25 specifies the narrowest portion of the coil as the minimum width from the longitudinal width distribution of the coil sent from the hot rolling process. However, a representative width such as an average width in the coil may be specified. The minimum width or the representative width obtained in this way is compared with the target plate width in the hot rolling step, and the increase ΔE of the elongation rate in the tension leveler is set according to the magnitude of the deviation. Is sent to the tension leveler controller 26.

The tension leveler controller 26 gives a command to the intermesh controller 27 to set an intermesh set in advance for each steel type and size in accordance with the timing at which the coil reaches the tension leveler. At the same time, the extension rate control is performed with the extension rate obtained by adding ΔE to the normal extension rate set value as the target extension rate.

In the data processing device 25, the measured value of the plate width in the longitudinal direction of the coil measured by the plate width meter 28 installed on the entrance side of the tension leveler is compared with the target plate width in the hot rolling process. A command is sent to the tension leveler controller 26 for the amount of change ΔI of the tension leveler intermesh according to the deviation.

The tension leveler controller 26 predicts the time from when the steel strip passes through the width gauge 28 to when the steel strip reaches the tension roll 21 of the tension leveler, and the timing at which the strip width measurement position reaches the tension leveler. Then, a value obtained by adding the intermesh change amount ΔI to the normal intermesh set value is sent to the intermesh control device 27. The intermesh control device 27 includes:
The position of the elongating roll 22 is changed so as to match the instructed intermesh.

In the embodiment of the present invention described above, a tension leveler for performing constant elongation rate control automatically adjusts the tension so that the elongation rate becomes constant while fixing the intermesh. This is based on the presumption of the extension rate control method in the usual tension leveler. In this case, the means (2) to (5) of the present invention
By changing the intermesh in the tension leveler as described above, the original object can be achieved.
However, if a tension level control system that automatically adjusts the intermesh while keeping the tension constant is used as the tension leveler control method for performing the constant elongation rate control, the tension will be applied instead of the intermesh. It is necessary to adjust the plate width in the coil by changing.
In this case, the same effect as the above-described means can be obtained.

[0055]

<Embodiment 1> An embodiment according to the means (1) of the present invention will be described. The object of the present embodiment is a hot-rolled steel strip of ordinary steel, and the target sheet width of the hot-rolled steel strip is determined according to the above-described formula (1). In the case of this embodiment, the minimum trim allowance ΔWt is 9 mm, and the width reduction ΔWd in the tension leveler is 2 m.
m, the average value ΔWs of the excess width in consideration of the variation of the hot rolling width is set to 5 mm. Therefore, the target sheet width in the hot rolling process is the product width (the sheet width after trimming) W
A value obtained by adding 16 mm to p is set.

On the other hand, in the example according to the means (1) of the present invention, the actual value of the sheet width distribution in the longitudinal direction of the hot-rolled steel strip is sent to the data processing device 25 as shown in FIG. The data processing device 25 specifies the minimum value Wm of the plate width of the coil. The minimum value Wm is compared with a target plate width Wh in the hot rolling process of the coil. In the present embodiment, the deviation ΔWc is calculated using Expression (2).

ΔWc = Wm−Wh (2) The data processor 25 calculates the change amount ΔE of the extension rate in the tension leveler according to ΔWc. This change amount also changes depending on the steel type and size or the set value of the intermesh. For example, for ordinary steel having a thickness of 4.0 mm and a width of 1250 mm, a target elongation rate of 1.2% is set as a normal tension leveler setting condition. In this case, the width reduction ΔWd in the tension leveler is set. Is predicted to be 2 mm. At this time, the setting of the extension rate change amount of the tension leveler in the present invention is based on Expression (3).

[0058]

(Equation 1)

In the equation (3), when ΔWc is less than −3 mm, the operation is performed with the normal tension leveler set elongation rate, and when ΔWc is larger than that, the elongation rate is increased. ing. However, the upper limit of the elongation rate is set in consideration of the capability of the tension leveler.

FIG. 6 shows an example of the result of performing the plate width control based on such settings. FIG. 6 shows a comparison between the result according to the present invention and the result when the control by the tension leveler is not performed. The trim margin results on the horizontal axis represent the minimum width in the coil longitudinal direction, and indicate that the value of the minimum width in the coil varies from coil to coil. As can be seen from the figure, the trim width is reduced by performing the plate width control according to the method of the present invention. In addition, although the minimum trim margin ΔWt is set to 9 mm, it can be confirmed that an area with a width smaller than that, that is, an area with insufficient width does not appear. <Embodiment 2> Next, an embodiment according to the means (2) of the present invention will be described. Also in the present embodiment, the method of setting the target sheet width in the hot rolling step is the same as in the first embodiment.
In the example according to the means (2) of the present invention, the actual value of the sheet width distribution in the longitudinal direction of the hot-rolled steel strip is sent to the data processing device 25 as shown in FIG. The data processor 25 compares the measured value W (x) of the sheet width at the position x in the longitudinal direction of the steel strip with the target sheet width Wh in the hot rolling step, and calculates a deviation ΔW
(X) is calculated according to equation (4) as a function of the longitudinal position x.

ΔW (x) = W (x) −Wh (4) Further, the intermesh change amount ΔI (x) in the tension leveler according to the magnitude of the deviation ΔW (x).
Set. This change amount also changes depending on the steel type, size, or intermesh setting value. For example, for ordinary steel having a plate thickness of 4.0 mm and a plate width of 1250 mm, the target conditions for setting a normal tension leveler are a target elongation rate of 1.2% and an intermesh of 13 mm. At this time, the change amount of the intermesh is based on Expression (5).

[0062]

(Equation 2)

The intermesh change amount ΔI (x) determined in this way is sent to the tension leveler controller 26. The tension leveler controller 26 outputs a corresponding intermesh change amount to the intermesh controller 27 in accordance with the progress of the steel strip,
Based on this, the position of the extension roll 22 is changed.

FIG. 7 shows an example of the result of performing the plate width control based on the above settings. FIG. 7 shows the width distribution of the hot-rolled steel strip,
This is a comparison of the results obtained by controlling this using the control method of the present invention. In the present embodiment, the intermesh is changed in accordance with the plate width variation in the coil, and the trim amount is reduced on average and the variation can be reduced. <Embodiment 3> Next, an embodiment according to the means (4) of the present invention will be described. In this embodiment, the first embodiment and the second embodiment are combined to obtain a greater effect. The method for setting the target sheet width in the hot rolling step is the same as in the first embodiment. In the example according to the means (4) of the present invention, the actual value of the sheet width distribution in the longitudinal direction of the hot-rolled steel strip is sent to the data processing device 25 as shown in FIG. The data processor 25 calculates the minimum value Wm of the measured value W (x) of the plate width at the position x in the longitudinal direction of the steel strip. Further, the minimum value Wm is compared with the target plate width Wh in the hot rolling step, and the deviation ΔWc is obtained according to the equation (2). on the other hand,
The deviation ΔWg (x) between the measured value W (x) of the plate width at the longitudinal position x and the minimum value Wm is calculated as a function of the longitudinal position x according to the equation (6).

ΔWg (x) = W (x) −Wm (6) Further, in the data processing device 25, the expansion ratio target value is calculated in accordance with the width deviation ΔWc and ΔWg (x) calculated as described above. Change value ΔE and intermesh change amount ΔI
Calculate (x). In the present embodiment, the change amount ΔE of the target elongation rate corresponding to the width deviation ΔWc uses the value shown in Expression (3). On the other hand, the width deviation ΔWg at the longitudinal position x
For (x), the intermesh change amount ΔI (x) is calculated according to equation (7).

[0066]

(Equation 3)

The change amount ΔE and the intermesh change amount ΔI (x) of the elongation rate target value determined as described above.
Is sent to the tension leveler controller 26. In the tension leveler control device 26, a value obtained by adding the extension rate change amount ΔE shown in Expression (3) to the normal set value is set as the target extension rate in accordance with the timing at which the steel strip reaches the tension leveler. . On the other hand, with respect to the fluctuation in the coil, the corresponding intermesh change amount ΔI (x) is output to the intermesh control device 27 in accordance with the progress amount of the steel strip, and the position of the extension roll 22 is changed based on the output. Be changed.

FIG. 8 shows an example of the result of controlling the sheet width based on the above settings. FIG. 8 shows the width distribution of the hot-rolled steel strip,
This is a comparison of the results obtained by controlling this using the control method of the present invention. In the present embodiment, the elongation ratio is changed with respect to the variation between the coils, and the intermesh is changed in accordance with the plate width variation in the coil, and it is possible to significantly reduce the trim amount. You can see that it has become.

[0069]

As described above, according to the present invention,
In producing a hot-rolled steel strip through a hot rolling step, a pickling step having a tension leveler on the entrance side of the pickling tank, by controlling the sheet width using a tension leveler installed in the pickling step, Variations in plate width between and within the coils of the hot-rolled steel strip can be reduced, and trim scrap in the trimming step can be reduced. Further, since the method is not based on the tension leveler elongation rate control performed in the prior art, the acidity is not impaired, and the thickness accuracy after cold rolling is not adversely affected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of the arrangement of the main components of a pickling line (pickling step) used in the description of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a concept of a width design of a hot-rolled steel strip.

FIG. 3 is a diagram showing a behavior of a plate width change in a tension leveler.

FIG. 4 is a first diagram showing an example of the arrangement of the main equipment of a tension leveler section provided in the pickling step in order to carry out the present invention.
Figure.

FIG. 5 is a second diagram showing an example of the arrangement of the main equipment of the tension leveler provided in the pickling step in order to carry out the present invention.
Figure.

FIG. 6 is a diagram showing an example of a trim amount reduction effect according to the method of the present invention in the first embodiment.

FIG. 7 is a diagram showing an example of a trim amount reduction effect according to the method of the present invention in the second embodiment.

FIG. 8 is a diagram showing an example of a trim amount reduction effect according to the method of the present invention in the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Payoff reel 2 Steel strip (hot rolled steel strip) 3 Rough leveler 4, 14, 19 Shearing machine 5 Welding machine 6, 13 Looper 7 Tension leveler part 8 Tension leveler 9, 10, 16, 20, 24 Bridle roll 11 Pickling tank 12 Trimming device 15, 18 Coiler (tension reel) 17 Cold rolling mill 21, 22 Extension roll 23 Deflector roll 25 Data processing device 26 Tension leveler control device 27 Intermesh control device 28 Board width meter

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuhiro Soya 1-2-1, Marunouchi, Chiyoda-ku, Tokyo F-term in Nihon Kokan Co., Ltd. 4E003 AA02 BA24

Claims (5)

[Claims] In producing a hot-rolled steel strip through a hot-rolling step and a pickling step having a tension leveler on the entrance side of a pickling tank, a strip width in the longitudinal direction of the strip after rolling in the hot-rolling step The distribution is continuously measured, in the pickling process, the minimum width or the representative width of the steel strip specified based on the strip width distribution in the longitudinal direction of the steel strip after rolling measured continuously in the hot rolling step. Manufacturing a hot-rolled steel strip, wherein the elongation rate when the steel strip passes through the tension leveler is corrected from a preset value according to a difference from a target strip width in a hot rolling step. Method. 2. A hot-rolling process, in which a hot-rolled steel strip is manufactured through a pickling process having a tension leveler on an entrance side of a pickling tank, a strip width in the longitudinal direction of the steel strip after rolling in the hot-rolling process. The distribution is continuously measured, in the pickling step, according to the difference between the strip width distribution in the steel strip longitudinal direction after rolling measured continuously in the hot rolling step, and the target strip width in hot rolling. A method for manufacturing a hot-rolled steel strip, wherein an intermesh when the position of the steel strip passes through the tension leveler is corrected from a preset value while keeping the elongation rate constant. In producing a hot-rolled steel strip through a hot rolling step and a pickling step having a tension leveler on an entrance side of a pickling tank, in the pickling step, the steel strip is formed on the entrance side of the tension leveler. The width distribution in the longitudinal direction is continuously measured, and the elongation is kept constant according to the difference between the measured continuous width distribution of the steel strip and the target width in hot rolling. While keeping
A method for manufacturing a hot-rolled steel strip, comprising correcting an intermesh when the position of the steel strip passes through a tension leveler from a preset value. 4. A hot-rolling process, in which a hot-rolled steel strip is manufactured through a pickling process having a tension leveler on an entrance side of a pickling tank, a strip width in the longitudinal direction of the strip after rolling in the hot-rolling process. The distribution is continuously measured, in the pickling process, the minimum width or the representative width of the steel strip specified based on the strip width distribution in the longitudinal direction of the steel strip after rolling measured continuously in the hot rolling step. According to the difference from the target plate width in the hot rolling step, the elongation rate when the steel strip passes through the tension leveler is corrected from a preset value, and the elongation rate corrected in the above elongation. While maintaining the rate, the width of the strip in the longitudinal direction of the steel strip after rolling continuously measured in the hot rolling step, and the minimum width or the representative width of the steel strip specified in the longitudinal direction of the steel strip. Depending on the continuous width deviation, the position of the strip in passing through the tension leveler is A method for manufacturing a hot-rolled steel strip, comprising modifying an intermesh from a preset value. 5. In producing a hot-rolled steel strip through a hot rolling step and a pickling step having a tension leveler on an entrance side of a pickling tank, a strip width in a longitudinal direction of the strip after the hot rolling step is performed. The distribution is continuously measured, in the pickling process, the minimum width or the representative width of the steel strip specified based on the strip width distribution in the longitudinal direction of the steel strip after rolling measured continuously in the hot rolling step. According to the difference between the target strip width in the hot rolling process, the elongation rate when the steel strip passes through the tension leveler is corrected from a preset value, and further, the steel strip at the entry side of the tension leveler. The width distribution in the longitudinal direction of the steel strip is continuously measured, and the deviation from the target width in hot rolling is determined in the longitudinal direction of the steel strip. While maintaining the elongation rate corrected, the position of the steel strip is A hot-rolled steel strip, wherein the intermesh when passing through the steel sheet is corrected from a preset value.