KR100423424B1 - Method For Widthwide Rolling Steel Plate - Google Patents

Abstract

The present invention relates to a method of rolling a thick steel plate using a steel sheet rolling equipment after the vertical mill (Edger Mill) for the lateral rolling is installed, the thickness factor of the side material when calculating the exit width of the material after the width rolling The purpose of the present invention is to provide a width rolling method of a thick steel sheet which can improve the width control accuracy of the material by correcting the width of the material before rolling due to the inaccurate width of the material before rolling.

The present invention calculates the maximum width and average width of the entry material using the measurement value of the width / length meter, calculates the entry inversion width by the meter metric using the rolling mill spacing and the width rolling load collected during the width rolling, The main purpose of this method is to calculate the width of the shape by applying the shape-wise correction of the thickness of the material by comparison analysis with the average width of the length gauge, and to calculate the exit width of the material after rolling. do.

Description

Method for Widthwide Rolling Steel Plate

The present invention relates to a method for rolling a thick steel plate using a steel sheet rolling equipment after the vertical mill (Edger Mill) for the width direction rolling is installed, in more detail

The present invention relates to a method for rolling a steel sheet after the width control of the material can be improved.

The rolling of the thick steel sheet can be divided into two types, rolling in width direction and rolling in thickness direction. Double width rolling is performed by even rolling, width rolling, length rolling, and the like. The reason for performing the widthwise rolling is to control the longitudinal width deviation of the final material in the lengthwise rolling, which is the final stage of the material rolling process, and to achieve the desired width desired by the demand.

Conventionally, the width | variety of the raw material after width rolling was calculated | required as following formula (1).

Width of material after rolling = average width of measurement-width reduction by width rolling

That is, as shown in Equation (1), the width of the raw material after rolling is obtained by subtracting the width reduction due to the width rolling from the average width measured by the width / length meter installed on the upper part of the rolling mill. However, since the material subjected to the width rolling is not a uniform cross section in the thickness direction as shown in Fig. 1, the measurement width differs from the actual one. This phenomenon results in the failure to measure the exact width of the material in the thickness direction of the material, regardless of the width measurement method on the upper surface or the side. Therefore, the width of the material after rolling by the conventional method based on Equation (1). If you calculate, then the width calculation may not be accurate.

In this phenomenon, as shown in FIG. 2, when the interval between the vertical mills is continuously narrowed in the width direction of the material, a small load is generated compared to the vertical mill interval reduction in the initial constant section m, but the section having a uniform cross section ( In n), the detected rolling load increases with a constant proportionality to the vertical mill spacing.

Therefore, the average width measured by the width rolling mill as Equation (1) is calculated as the entrance width of the material, and the width reduction calculated by applying the Gauge Meter equation using the detection load and rolling mill spacing during rolling is calculated. It can be seen that the conventional method for calculating the measurement width has a significant measurement error width.

The present inventors have conducted research and experiments to solve the above-mentioned problems of the prior art, and based on the results, the present invention proposes the present invention. In the present invention, the thickness direction of the entrance material is calculated when calculating the exit width of the material after rolling. The purpose of the present invention is to provide a width rolling method of a thick steel sheet which can improve the width control accuracy of a material by correcting an inexact material width before rolling due to a shape factor to obtain a more accurate exit width.

1 is a schematic diagram showing a phenomenon in which a measurement error occurs in width / length measurement due to a shape defect in the thickness direction of a material.

Figure 2 is a schematic diagram showing the change in rolling load according to the decrease in the interval of the vertical rolling mill

Figure 3 is a flow chart sequentially showing the process of rolling the thick steel plate in accordance with the present invention

Figure 4 is a schematic diagram showing the change in the cross-section of the material by the width direction rolling and longitudinal rolling during thick plate rolling

5 is a graph showing the change of the shape correction factor application ratio according to the material entrance width

Figure 6 is a graph showing the width deviation before and after the application of the present invention

The present invention is a method for width rolling a thick steel plate using a steel sheet rolling equipment after the vertical rolling machine for the width direction rolling is provided,

Measuring the width and length of the material before the width rolling, and obtaining a maximum width (MW) and an average width (AW);

Measuring the gap (MEG) of the vertical rolling mill and the load (MEF) applied to the rolling mill during the width rolling by the set vertical rolling mill spacing;

Obtaining a material width (TW1) after passing the rolling mill by the following equation (2) using the vertical rolling mill (MEG) and the load (MEF) measured as described above;

TW1 = MEG + MEF / M + C

TW1: Material width after the width rolling mill passes by the gauge meter type

MEG: Vertical rolling mill spacing measured during width rolling

MEF: Load applied to vertical rolling mills measured during rolling

M, C: intrinsic constant of vertical mill

Obtaining a width rolling amount by the following equation (3) using the width of the width of the side width and the width of the material after passing the width rolling mill according to the above formula (2);

Rolling capacity = Average width of entrance gauge-Width of material after rolling

Obtaining the meter metric calculated width reduction amount (AMOUNT) by the rolling by the following equation (4) using the rolling efficiency determined by the width rolling amount and the steel grade characteristics obtained as described above;

AMOUNT = rolling efficiency × width rolling amount

Obtaining the inversion incidence width (IWG) by the following equation (5) using the obtained material width (TW1) and the width of the rolling roll after passing through the obtained width rolling mill;

IWG = TW1 + Rolling Amount

Obtaining a width deviation ratio (DWR) by the following equation (6) using the inverse lateral width IWG and the width / length measurement width before length rolling width AW;

DWR = (AW-IWG) / AW

Obtaining a shape factor application ratio (F) by the following equation (7);

F = α × {CTH / STH + (MW-AW) / AW}

CTH: material thickness during rolling

STH: Initial Slab Thickness

MW: Maximum width before rolling

AW: Average width before width rolling (average width of width / length measurement) α: 0.5 to 0.7

Obtaining a thickness direction shape correction coefficient (TF) by the following equation (8) using the width deviation ratio (DWR) and the shape factor application ratio (F) obtained in the above formulas (6) and (7);

TF = A × DWR × F

A: 1 (DWR <0)

-1 (DWR> 0)

0 (DWR = 0)

Obtaining the entrance width IWF corrected using the thickness direction shape correction coefficient TF obtained as described above by using Equation (9);

IWF = AW + (AW × TF)

AW: width / length measurement average width

Obtaining the corrected exit width TW2 by the following equation (10) using the corrected entrance width IWF and the reduced amount AMOUNT; And

TW2 = IWF-AMOUNT

And a step of repeating the above steps until the difference between the corrected measurement width and the final target width of the material is within an acceptable range.

Hereinafter, the present invention will be described in more detail. First, in the present invention, "width / length gauge" means the width measured by the width / length gauge.

As shown in FIG. 3, the post steel sheet measures the width and the length of the raw material using the width / length meter installed on the upper part of the rolling mill before performing the widthwise rolling. At this time, the measured value can be analyzed to find the maximum width and average width of the material.

As described above, when the measurement of the width / length meter is finished, rolling is performed to obtain a desired width.

In general, the target width cannot be obtained by only one rolling, and two to four width rolling is performed.

During the width rolling, the distance between the rolling mill and the rolling load are measured by various sensors installed in the rolling mill. Using the measured rolling mill spacing, rolling load and rolling mill constant, the width of the material TW1 after passing through the rolling mill by the Gauge Meter formula is obtained by the following formula (2).

(Equation 2)

TW1 = MEG + MEF / M + C

Usually, the reason why the material width TW1 after passing through the rolling mill by a meter metric system is not used as the exit width of the rolling is that the thick plate rolling performs the rolling in the width direction and the rolling in the thickness direction simultaneously. This cross section change is shown in FIG. 4.

As shown in Figure 4, by the widthwise rolling the workpiece is swelled at both ends in the form of dog-bone (Dog-Bone). When the rolling in the thickness direction in this shape is recovered by a certain amount of width rolling by the width rolling. This recovery depends on the nature of the material. The efficiency by which the width is reduced by such rolling is referred to as rolling efficiency [width rolling efficiency = (width rolling amount recovery amount) / width rolling amount].

The rolling efficiency is an intrinsic value determined by rolling mill characteristics and steel grade characteristics.

The width reduction amount is calculated using the width rolling amount and the rolling efficiency.

That is, the width rolling amount and width reduction amount (AMOUNT) by the width rolling can be calculated | required by following formula (3) and (4), respectively.

(Equation 3)

Roll width = Average width of entrance gauge-Width of material after rolling

(Equation 4)

AMOUNT = rolling efficiency × rolling capacity

The inverse incidence entrance width (IWG) is obtained by the following equation (5) using the calculated meter width after passing the metered metric rolling mill and the width of the rolling roll obtained by the formulas (2) and (3).

(Equation 5)

IWG = TW1 + Rolling Amount

The width deviation ratio (DWR) is obtained by comparative analysis of the inversion side width obtained by the above equation (5) and the average width of the pre-rolled rolling material based on the following equation (6).

(Equation 6)

DWR = (AW-IWG) / AW

The width deviation ratio (DWR) obtained as described above is a measurement error of the width / length gauge that measures the width largely based on the shape factor of the thickness direction of the material, and the width decrease is large due to the uneven cross section. It is calculated to calibrate the existing instrument metric calculations that yield small width reductions.

It is not reasonable to apply the thickness shape influence factor equally due to the dimensional effects such as width deviation and thickness influence of the material before deriving the thickness direction shape correction coefficient by reflecting the width deviation ratio.

That is, even if the same width is thick, if the thickness is thick, it is more affected by the thickness shape factor, and even if the width is the same, if the width deviation of the material is large, the influence is also large. Therefore, the width deviation ratio is differentially applied by the following equation (7). The shape factor factor application ratio F is computed.

(Equation 7)

F = α × {Material thickness (CTH) / initial slab thickness (STH) + (maximum width (MW)-average width (AW)) / average width (AW)} α: 0.5 to 0.7

As can be seen from FIG. 5 showing an example, the shape factor application ratio F increases as the thickness increases and the width deviation increases.

It is preferable that the said shape factor application ratio F is calculated | required by following formula (7a).

F = 0.6 × {material thickness (CTH) / initial slab thickness (STH) + (maximum width (MW)-average width (AW)) / average width (AW)}

The thickness direction shape correction coefficient (TF) is calculated based on Equation (8) by applying the width deviation ratio and the shape factor application ratio obtained as described above.

(Equation 8)

TF = A × width deviation ratio (DWR) × shape factor application ratio (F)

A: 1 (width deviation ratio <0)

0 (width deviation ratio = 0)

-1 (width deviation ratio> 0)

Using the thickness direction shape correction coefficient TF calculated | required as mentioned above, and the average width before width rolling width measurement, the correction | amendment side width | variety IWF is calculated | required based on following formula (9).

(Equation 9)

IWF = AW + (AW × TF)

When the width reduction amount by the said rolling is excluded from the correction entrance width IWF calculated | required above, it will become the exit calculation width | variety after the said width rolling as shown in following formula (10).

(Equation 10)

TW2 = IWF-AMOUNT

By repeating the above steps until the deviation between the measurement width TW2 obtained as described above and the target width of the material falls within the allowable range, the degree of width control of the material is improved.

The allowable range is preferably ± 5 mm or less.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example

As shown in Fig. 6, although the deviation from the width measured by the calculation width final width measuring device was 11.0 mm in error on the average of 4.4 mm before the application of the present invention [Fig. 6 (a)], the present invention After the application of, it can be seen that the average deviation of 3.1mm has a deviation of 6.4mm (Fig. 6 (b)).

Therefore, it can be seen that a significant level of width control can be improved when the present invention is applied.

As described above, the present invention has an effect of improving the width control degree of the material during the width rolling of the thick steel sheet.

Claims (3)

In the method of rolling the thick steel plate using a steel sheet rolling equipment after the vertical rolling machine for rolling in the width direction is provided, Measuring the width and length of the material before the width rolling, and obtaining a maximum width (MW) and an average width (AW); Measuring the gap (MEG) of the vertical rolling mill and the load (MEF) applied to the rolling mill during the width rolling by the set vertical rolling mill spacing; Obtaining a material width (TW1) after passing the rolling mill by the following equation (2) using the vertical rolling mill (MEG) and the load (MEF) measured as described above; (Equation 2) TW1 = MEG + MEF / M + C TW1: Material width after the width rolling mill passes by the gauge meter type MEG: Vertical rolling mill spacing measured during width rolling MEF: Load applied to vertical rolling mills measured during rolling M, C: intrinsic constant of vertical mill Obtaining a width rolling amount by the following equation (3) using the width of the width of the side width and the width of the material after passing the width rolling mill according to the above formula (2); (Equation 3) Rolling capacity = Average width of entrance gauge-Width of material after rolling Obtaining the meter metric calculated width reduction amount (AMOUNT) by the rolling by the following equation (4) using the rolling efficiency determined by the width rolling amount and the steel grade characteristics obtained as described above; (Equation 4) AMOUNT = rolling efficiency × rolling capacity Obtaining the inversion incidence width (IWG) by the following equation (5) using the obtained material width (TW1) and the width of the rolling roll after passing through the obtained width rolling mill; (Equation 5) IWG = TW1 + Rolling Amount Obtaining a width deviation ratio (DWR) by the following equation (6) using the inverse lateral width IWG and the width / length measurement width before length rolling width AW; (Equation 6) DWR = (AW-IWG) / AW Obtaining a shape factor application ratio (F) by the following equation (7); (Equation 7) F = α × {CTH / STH + (MW-AW) / AW} CTH: material thickness during rolling STH: Initial Slab Thickness MW: Maximum width before rolling AW: Average width before width rolling (average width of width / length measurement) α: 0.5 to 0.7 Obtaining a thickness direction shape correction coefficient (TF) by the following equation (8) using the width deviation ratio (DWR) and the shape factor application ratio (F) obtained in the above formulas (6) and (7); (Equation 8) TF = A × DWR × F A: 1 (DWR <0) -1 (DWR> 0) 0 (DWR = 0) Obtaining the entrance width IWF corrected using the thickness direction shape correction coefficient TF obtained as described above by using Equation (9); (Equation 9) IWF = AW + (AW × TF) AW: width / length measurement average width Obtaining the corrected exit width TW2 by the following equation (10) using the corrected entrance width IWF and the reduced amount AMOUNT; And (Equation 10) TW2 = IWF-AMOUNT AMOUNT: Width reduction due to the rolling And repeating the above steps until the difference between the corrected measurement width and the final target width of the material is within an acceptable range. The method of claim 1, wherein the shape factor application ratio F is obtained by the following equation (7a). (Equation 7a) F = 0.6 × {material thickness (CTH) / initial slab thickness (STH) + (maximum width (MW)-average width (AW)) / average width (AW)} 3. The method of claim 1 or 2, wherein the allowable range is ± 5 mm or less.