JPH05269527A - Method for controlling flat shape of metallic strip - Google Patents

Abstract

PURPOSE:To effectively remove defectiveness of flatness of a metal strip by using a roll directly before the last roll of tension levelers as a shape detecting roll and changing the setting of indentation of the roll in accordance with its flatness information CONSTITUTION:A slab is rolled by a group 3 of finish rolls, cooled by a hot run table 4 and defectiveness of flatness is straightened by hot tension levelers 5 to be taken up by down coilers 6. The center of the last three rolls 81,82,83 of the hot tension levelers 5, that is, the roll 82 directly before the last roll 83 is made a shape detecting roll 82 which can measure a distribution in the width direction of the shape detecting roll 82. The identation of the roll is changed so that the deviation of tension detected by the shape detecting roll 82 is dissolved. Defectiveness of flatness in the time of hot rolling or finish rolling can be removed and trouble in the time of taking up of the down coilers 6 can be prevented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to flatness control devices for metal strips. More specifically, the present invention relates to a flatness control device for hot-rolled steel strips in hot rolling, for example.

[0002]

2. Description of the Related Art In order to meet the demand for further improvement in accuracy of rolled products due to recent technological advances, for example, the shape (flatness) of a rolled metal strip is detected by a shape detection device and based on this detection signal. The method of controlling the roll deflection and crown amount of the rolling mill has been developed.

When performing such shape detection, since the metal strip is generally flat due to the state in which high tension is applied, the metal strip is required to measure the true flatness. A method of mainly detecting the tension distribution in the width direction and estimating the shape from the value is adopted.

For example, as a means for online measuring the shape of a metal strip represented by a thin steel strip, the tension applied to the metal strip in response to the longitudinal extension of the metal strip when tension is applied to the metal strip. It is common to measure the width direction distribution of the metal strip and determine the width direction shape of the metal strip from the tension distribution.

[0005]

FIG. 7 is a schematic explanatory view of a conventional hot rolling line in which a slab from a heating furnace 1 passes through a group of rough rolling mills 2 to a group of finish rolling mills 3. It is cooled by the hot run table 4 and wound on the down coiler 6. However, in such a conventional method, even when the finish rolling mill group 3 has a flat shape, it is caused by uneven cooling during cooling on the hot run table 4 up to the down coiler 6. The flat shape sometimes deteriorated.

As a method for solving this problem, as shown in the drawing, a hot tension leveler 5 is arranged between the hot finish rolling mill and the down coiler, and a flatness defect generated in the hot run table 4 is introduced into the down coiler 6. The method of straightening before is disclosed in JP-A-54-28766. In this case, it is desirable to install the hot tension leveler 5 as close to the down coiler 6 as possible from the viewpoint of reducing the flatness failure portion.

When the tension leveler is used in a conditioning line or the like, the roll setting and the like are performed by model calculation in advance, and while the operator sees the actual shape of the metal strip, it is necessary to slightly change the crown amount of the VC level of the tension leveler. It is the usual practice to make adjustments.

However, the speed of the metal strip that has passed through the hot rolling finishing mill group 3 reaches 600 to 1000 m / min, and the down coiler 6 immediately leaves the tension leveler 5.
It is virtually impossible to make adjustments by the operator's operation because it will be wound up.

An object of the present invention is to provide a more practical control method for disposing a tension leveler in the vicinity of a down coiler in order to correct a flatness defect that occurs in a hot run table.

[0010]

[Means for Solving the Problems] As a result of various studies on the above problems, the flatness of the metal strip was measured at the outlet of the tension leveler using a shape detection roll, and the flatness of the shape detection roll was pushed based on the flatness. The present invention has been completed by finding that the roll setting of the tension leveler may be adjusted online by adjusting the amount.

Here, the present invention provides a method for controlling the flatness of a metal strip by applying a bending tensile force to the metal strip with a tension leveler arranged in a rolling line to correct the flatness of the metal strip, immediately before the final roll of the tension leveler. The roll is a shape detection roll capable of measuring the widthwise distribution of tension of the metal strip, and at least one of the rolls including the shape detection roll is based on the flatness information of the metal strip from the shape detection roll. A flatness control method for a metal strip, characterized in that a flat shape of the metal strip is controlled by changing a push amount setting.

[0012]

The operation of the present invention will be described in detail below using a steel plate as an example of a metal strip. FIG. 1 is a schematic explanatory view of a hot rolling line for carrying out the flat shape control method according to the present invention. The same members as those in FIG. 7 are designated by the same reference numerals.

In the figure, in the case of thin steel sheet rolling, the tip of the steel sheet goes out from the exit of the final rolling mill 31 of the hot rolling finish rolling mill group 3 through the hot run table 4 to the down coiler 6. After that, most of the rolling period is tensioned, except for a short time before it is rolled into the down coiler 6 and from when the rear end of the steel sheet exits the rolling mill outlet to when it is rolled into the down coiler 6. It is in the added state.

Therefore, in order to measure the flatness shape of the steel sheet, a method of measuring the widthwise distribution of the steel sheet tension caused by the application of tension and then obtaining the elongation distribution in the widthwise direction is used. It is common.

As a shape detecting device based on such a method, a plurality of rolls incorporating a load detector for detecting a radial load, such as disclosed in Japanese Patent Laid-Open No. 3-142308, are laminated and integrally formed. Suitable roll type shape detection rolls. In this case, the entire roll is pressed against the steel plate, the radial component of the tension of the steel plate applied to each roll is obtained, and the steel plate shape is estimated from the data thus obtained.

However, the shape detecting roll used in the present invention is not limited to a specific one, and any shape and type may be used as long as they do not violate the gist of the present invention.

In the present invention, as shown in FIG. 1, the above-mentioned shape detecting roll 82 is included in the roll group of the tension leveler 5.
It is incorporated in the roll 82 immediately before the roll 83 on the most down coiler side. This is because the steel plate that has entered the tension leveler is gradually corrected in flatness by the bending and tensile force of the rolls arranged above and below the pass line, so to detect the effect, the most exit side of the leveler is detected. That is, it is necessary to install the shape detection roll on the down coiler side.

Further, in the shape detecting method adopted in the present invention, it is necessary to wind the steel plate around the shape detecting roll at a constant angle. Considering this point, the steel sheets are arranged above and below the pass line as shown in FIG. The last three rolls 81, 82,
It is preferable to incorporate the shape detection roll 82 in the middle of 83, that is, in the roll immediately before the final roll.

According to the present invention, the pushing amount is changed in order to eliminate the defective shape detected by the shape detecting roll 82, that is, the tension deviation. When the shape correction is insufficient by only pushing by the shape detecting roll, not only the pushing amount of the shape detecting roll 82 but also the pushing amount of at least one of the rolls of the tension leveler may be changed. That is, generally, the pushing amount of at least one roll of the entire roll including the shape detecting roll may be changed, but preferably, the pushing amount of the shape detecting roll is changed.

The specific control operation in the method of the present invention may be performed as follows. If the tension distribution detected by changing the pushing amount of the shape detection roll becomes flat, the shape is flat and further control is unnecessary. The pushing amount of the shape detection roll is a certain value (mechanical strength,
However, if the tension distribution does not become flat, the amount of pushing of the roll on the upstream side of the shape detection roll is changed to improve the shape of the plate entering the shape detection roll. Get closer to flat. When the tension distribution detected by the shape detection roll does not become flat, the operation of is sequentially performed on the upstream side.

As shown in FIGS. 2 and 3, generally, a plurality of shape detecting devices 23 are arranged in the axial direction (9 in the example shown in FIG. 2).
A bearing 26 is provided between the divided sleeve 21 and at least the fixed shaft 25 having a fan-shaped cross section in the length region in which the sleeve 21 is fitted, and the radial load acting on the sleeve 21 is fixed to the bearing 26. It is a so-called fixed shaft type split roll that can be detected by the load detector 22 incorporated in the space between the shaft 25 and the shaft. The bearing 26 fitted on the fixed shaft 25 is supported by thrust bearings 24 provided outside the sleeves at both ends so as not to fall off. In the shape detecting device 23, the position of the load detector 22 is fixed with respect to the fixed shaft 25, so that the structure is simple, maintainability is good, and the resolution of shape detection in the width direction is relatively easy. In the figure, 23 is a nut.

On- line elongation measuring method: JP-A-3-1
As disclosed in Japanese Patent No. 42308, the load F applied to one sleeve 21 is expressed by the following equation (1). F = 2T · Sin θ (1) T = σ · w · t (2) where σ: tensile stress w: sleeve width t: thickness of steel plate θ: wrapping angle of steel plate.

When the Young's modulus of the steel sheet is E, the elongation rate ε due to tension is expressed by the following equation (3). σ = ε · E (3) Therefore, the following equation (4) is obtained from the equations (1), (2), and (3).

[0024]

[Equation 1]

If the tension component force Fi applied to each sleeve 21 is obtained from the equation (4), the elongation ε _i can be found. From there,
The elongation distribution can be obtained. Incidentally, 30kg / mm ² tensile stress σ is cold when the steel sheet, the steel sheet to about 2 kg / mm ² in the hot is elastically deformed. Therefore, from equation (3), the steepness is 2.4% in the cold (E = 2.1 × 10 ⁴ kg / mm ² ) and the steepness is 0.9% in the hot (E = 1.0 × 10 ⁴ kg / mm ² , at 1000 ° C). It is possible to measure up to a considerable degree of elongation.

Actually, since the tension measurement value of each sleeve is equal to the tension amount + the tension deviation amount, the tension deviation Δ
The elongation difference rate Δε is obtained using F as follows. That is, the tension Fi (i = 1-n) at each position of n points in the width direction
The tension deviation ΔFi is calculated from Next, the elongation difference rate Δε _i of the steel plate at each point is

[0027]

[Equation 2]

It is calculated as Δε obtained in this way
Is used to extract only the tension deviation. Next, the operation of the present invention will be described more specifically with reference to Examples.

[0029]

EXAMPLE With respect to the effect of the method according to the present invention, a hot coil rolling model test was conducted by using a rolling mill which is assumed to be 1/4 of an actual rolling mill by using a tester arranged as shown in FIG. Was carried out. For testing, 3.0t x 300W size
A hot coil of (mm) ordinary steel heated to 1100 ° C was used.
The steel plate unwound from the uncoiler 9 has two rolling mills 101,
After being continuously rolled at 102, it passed through a three-roll type tension leveler 11 and was wound on a coiler 13.

At that time, the shape L of the steel sheet before and after passing through the tension leveler was compared by changing the pushing amount L of the center roll 12 incorporating the shape detecting roll. here,
As shown in FIG. 5, the pushing L is L = 0 when the steel plate is traveling on a horizontal plane, and when the roll 31 is pushed downward to wind the steel plate around the roll circumferential surface, the drooping amount of the roll 31 is X. If there is, the pushing amount L = X.

The results are summarized in FIG. In the figure, the number on the horizontal axis is the number given to each tension measuring sleeve from one end of the shape detecting roll 12 to the other end. From the results shown in the figure, it is also understood that the correction amount of the plate shape can be changed by changing the pushing amount L of the roll. In other words, for example, if tension deviation is found when a shape is detected with a pushing amount of 10 mm, it means that there is a shape defect in the width direction. Can correct defects.

When the flatness of the steel sheet whose flatness was secured by tension control according to the present invention was measured offline, it was confirmed that the flatness was achieved.

[0033]

Industrial Applicability According to the present invention, flatness defects during hot rolling and finish rolling can be effectively removed, and troubles during winding of a down coiler can be prevented. Above all extremely beneficial.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a tension leveler of the present invention.

FIG. 2 is a perspective view of a shape detection roll used in the present invention.

3 is an explanatory diagram of a configuration of each detection roll of the shape detection roll of FIG.

FIG. 4 is an explanatory diagram of the equipment layout of the model test according to the embodiment of this invention.

FIG. 5 is an explanatory diagram of a roll pushing amount.

FIG. 6 is a diagram showing test results regarding the effect of a tension leveler.

FIG. 7 is an explanatory diagram of a conventional hot rolling process.

[Explanation of symbols]

1: Heating furnace 2: Rough rolling mill group 3: Finishing rolling mill group 4: Hot run table 5: Hot tension leveler 6: Down coiler 31: Final finishing mill 81,82,83: Tension leveler roll 9: Uncoiler 101,102: Rolling Machine 11: 3-roll type tension leveler 12: Shape detection roll 13: Coiler

Claims (1)

[Claims] 1. A flat shape control method for a metal strip in which a bending level is applied to a metal strip by a tension leveler arranged in a rolling line to correct the flatness, and a roll immediately before the final roll of the tension leveler is set to a metal strip. A shape detection roll capable of measuring the widthwise distribution of tension, and based on information on flatness of the metal strip from the shape detection roll, at least one roll indentation amount of each roll including the shape detection roll is set. Is controlled to change the flat shape of the metal strip.