KR100406407B1 - A Method for Manufacturing Steel Plate with Superior Width Accuracy - Google Patents

Abstract

The present invention relates to a method for manufacturing a thick steel plate in a steel plate factory of a steel mill in which a vertical rolling mill and a horizontal rolling mill are installed, and more precisely by learning the edging efficiency affected by operating conditions by using the width measurement results after edging and horizontal rolling. The present invention seeks to provide a method for manufacturing a thick plate which can further improve the width by using the same.

The present invention is a method for manufacturing a thick steel sheet using a thick plate rolling equipment comprising a vertical rolling mill edger and a horizontal rolling mill,

After edging and horizontal rolling, measure the width of the rolled material to obtain a higher degree of edging efficiency, and use this value to calibrate the existing edging efficiency, and apply this corrected edging efficiency to the next pass or the next rolled material. The method of producing a steel sheet after having excellent width degree which can improve the width degree by application is made into the summary.

Description

A method for manufacturing steel plate with superior width accuracy}

The present invention relates to a method of manufacturing a thick steel plate (hereinafter referred to as "thick plate") in a steel mill in a steel mill in which a vertical rolling mill (hereinafter referred to as "edger") and a horizontal rolling mill is installed. It is related with the manufacturing method of the thick plate which can improve the width | variety by using the edging efficiency calculated | required using the rolling measured using the following (hereinafter referred to as "egding") and the width measured with the measuring instrument after horizontal rolling. .

In general, since the products produced in the thick plate process is wide and diverse, the rolled material is rotated 90 degrees on a plane to perform the breading rolling.

That is, as shown in FIG. 1 (a), the slab SL is first rolled in the plate length direction to uniformly select the slab thickness to satisfy the width rolling rolling conditions.

The even-rolled finished material SB is obtained by the so-called even-rolled rolling step X.

Next, this is rotated 90 degrees horizontally as shown in Fig. 1 (b) to roll the even-rolled finished material SB in the width direction to secure a predetermined width dimension.

By the so-called deburring rolling step Y, the deburring rolling completed material SW is obtained.

Again, this is carried out by 90 ° horizontal rotation as shown in Fig. 1 (c) to finish the rolling process Z in the longitudinal direction so as to obtain the target dimension by rolling in the longitudinal direction so as to obtain a predetermined plate thickness, length and mechanical properties. Get the PL again.

On the other hand, the rolling roll becomes convex or concave at the center of the roll due to thermal expansion and abrasion during rolling.

Due to this phenomenon, the stretching amount of the center portion and both edges of the steel sheet is different, and when the widthwise rolling of FIG. When the width of the center part is smaller than the line and the end part, the concave shape is concave, and in this state, the lengthwise rolling of Fig. 1 (c) is carried out as it is. As a result, the width becomes non-uniform, and a large crop of lines and tail ends occurs.

In particular, in the case of a thick steel sheet which produces a product by cutting the product into a rectangular shape, the width is uneven in the longitudinal direction of the steel sheet, and if the crop of lines and end portions is large, the amount of scrap cut is large and the error rate decreases.

In order to prevent this phenomenon, in recent years, by installing an edger 2, which is a vertical rolling mill, as shown in FIG. 3, the width is uniform in the steel plate length direction as shown in FIG. Is adjusted to be squared to improve the real rate.

When the widthwise rolling is performed using the edger, as shown in FIG. 3, the edges of the steel sheet 1 show a dog bone shape in which the edge 11 protrudes in the thickness direction. The dog bone spreads in the width direction again by horizontal rolling.

That is, the width of the steel sheet, which was Wo before edging, decreases as shown in FIG. 3 (b) after edging, and shows W1. When the steel sheet is cut in the vertical direction, the cut surface is shaped as a dog bone as shown in FIG. 3 (c). Becomes

When this steel sheet is horizontally rolled by the horizontal rolling mill 3 again, the dog bone formed by edging is spread in the width direction (hereinafter referred to as "width recovery") so that the steel sheet width is W1 to W2 and the cut surface at this time. Becomes a rectangular shape again.

Even if the edging is performed as described above, the amount of the actual width decreases significantly compared to the edging amount.

At this time, a value obtained by dividing the value of the actual width reduced by the edging by the edging amount is called edging efficiency [= (edge amount-width recovery amount) / edging amount].

In the case of edging using the edger as described above, when determining the target width of the plunger, the value of the width reduced by the edging should be compensated.

Accordingly, the calculation is performed by subtracting the value in which the width spreads in the width direction during the length rolling after deburring from the indicated width, and adding the amount of the width decreasing by edging.

At this time, the width reduction amount by edging is "edge amount x edging efficiency", so accurately predicting the edging efficiency is a very important factor to improve the width.

However, the edging efficiency is greatly affected by the thickness and width of the steel sheet, and is affected by the operating conditions such as the temperature of the material in operation, the wear of the rolling roll, thermal expansion, the cycle of use after the roll change, and the surface friction coefficient. If a fixed value is used for each width, there is a problem in that the width is lowered due to a difference from the actual.

MEANS TO SOLVE THE PROBLEM The present inventor made the research in order to solve the above-mentioned all the problems of the prior art, and based on the result, the present invention proposes the present invention. It is intended to provide a method of manufacturing a steel sheet that can be more accurately obtained by learning by using the measurement results and further improving the width by using the same.

1 is a schematic diagram showing a process of rolling a rolled material in a reversible rolling mill,

(a) shows the even rolling process which makes the thickness of a rolling material uniform,

(b) shows the breading-rolling process for satisfying the width of the product,

(c) represents the final length rolling process.

2 is a schematic book showing the steel sheet shape after rolling;

(a) shows a case where no edging is performed,

(b) shows the case of edging using a resin rolling mill.

3 is a schematic diagram showing a vertical and horizontal rolling process,

(a) shows the rolling process three-dimensionally,

(b) is a plan view of the steel sheet being rolled,

(c) is a cross-sectional view along A-A ', B-B', and C-C 'of the steel sheet shown in (b).

Figure 4 is a flow chart showing the edging efficiency learning process according to the present invention

5 is a graph showing the degree of exposing according to the present invention and the conventional method,

(a) shows the degree of exfoliation by the conventional method,

(b) shows the degree of exfoliation according to the present invention.

Explanation of symbols on the main parts of the drawings

SL. . . Slavic SB. . . Even rolling finished material

SW. . . Breadboard bet finish 1. . . Grater

2 . . . Edger (vertical rolling mill) 3. . . Horizontal rolling mill

Hereinafter, the present invention will be described.

The present invention is a method for manufacturing a thick steel sheet using a thick plate rolling equipment comprising a vertical rolling mill edger and a horizontal rolling mill,

Obtaining the target thickness (TATHwd) from the following equation (1) when the even rolling is finished;

TATHwd = SPTH × SPWD / ASWD. . . . . (One)

[Here, SPTH: thickness after rolling

SPWD: width after even rolling

ASWD: Rolling Target Width]

Obtaining a width spreading amount (WDspr) in the width direction during horizontal rolling after the blasting rolling by using the following equation (2);

WDspr = (TATHwd-ASTH) x α. . . . . (2)

[Where, TATHwd: target thickness

ASTH: Length Rolling Target Thickness

α: width spreading coefficient]

Calculating the width of target width (TAWwd) by using Equation (3) in consideration of the target edging amount and the amount of width spreading during horizontal rolling after the widthwise width obtained above;

TAWwd = ASWD-WDspr + Edrop. . . . . (3)

[Where, ASWD: rolling target width

Edrop: The value by which the width is reduced by edging (= Eamou × Heef (t, w))

Eamou: Target Edging Amount

Heef (t, w): Edging efficiency according to steel plate thickness (t) and width (w)]

Obtaining a corrected width target width TATHwd 'for achieving the width target width TAWwd obtained as described above using Equation (4);

TATHwd '= SPTH × SPWD / TAWwd. . . . . (4)

Exposing the rolled rolled roll material;

When the bake rolling is completed, the edge is set by the edge roll gap to achieve the edging amount, and then edging is performed, and the post-edge thread edging amount AEamou is obtained using Gauge Meter equation (5);

AEamou = Wo- (ERG + ERF / EDM) x TF. . . . . (5)

[Wo: Wo: width before edging

ERG: Edge Roll Gap

ERF: Edging Load

EDM: Edger Mill Integer

TF: Linear Shrinkage Compensation Coefficient (= 1-1.35E-5 × Steel Plate Temperature)]

Rolling the edged rolled material horizontally and measuring a width MWID of the rolled material;

Determining a recovery amount (WDrec) of the edging dogbone by the following equation (6) in consideration of the measurement width MWID and the width spreading amount due to horizontal rolling;

WDrec = MWID-(Wo-AEamou)-(Ho-H1) x α. . . . . (6)

[Wo, Wo: width before edging

Ho: Thickness before horizontal rolling

H1: Thickness after horizontal rolling

α: width spreading coefficient]

Obtaining a real edging efficiency Meef by the following equation (7) using the recovery amount WDrec and the actual edging amount AEamou obtained as described above;

Meef = (AEamou-WDrec) / AEamou. . . . . (7)

Obtaining a corrected edging efficiency [Heef (t, w) '] by the following equation (8) using the edging efficiency [Heef (t, w)] and the actual edging efficiency (Meef) for the rolled material described above;

Heef (t, w) '= Heef (t, w) + (Meef-Heef (t, w)) x G. . . . . (8)

[Here, Heef (t, w): edging efficiency that has been learned by thickness (t) and width (w) so far

G: Learning Gain]

After the even rolling of the next steel sheet, the width reduction amount (Edrop ') due to edging is performed on the even rolling material by using the correction edging efficiency [Heef (t, w)' obtained as described above by the following formula (9). Obtaining;

Edrop '= Eamou x Heef (t, w)'. . . . . (9)

During the deburring rolling of the even-rolled rolled material, deburring rolling so as to obtain a width of the sum of the defoamer target width (TAWwd) and the width reduction amount (Edrop ') due to edging; And

It relates to a method for producing a steel sheet after the width is excellent, including the step of edging and horizontal rolling the rolled rolled material as described above.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In order to learn the edging efficiency by the post-edge width results according to the method of the present invention, as shown in FIG.

At this time, since the volume after the even rolling is the same as the volume after the width rolling, according to the law of volume invariance, the width reduction target thickness can be obtained as in the following formula (1).

TATHwd = SPTH × SPWD / ASWD. . . . . (One)

[Here, SPTH: thickness after rolling

SPWD: width after even rolling

ASWD: Rolling Target Width]

Next, the width | variety of the width | variety (WDspr) by the width direction metal flow at the time of horizontal rolling is calculated | required using Formula (2).

WDspr = (TATHwd-ASTH) x α. . . . . (2)

[Where, TATHwd: target thickness

ASTH: Length Rolling Target Thickness

α: width spreading coefficient]

On the other hand, the width | variety spreading coefficient (alpha) at the time of length rolling is a value determined by the magnitude | size of a rolling material width, and the capability of a rolling mill, and a preferable value is about 0.05-0.20.

Next, a target edge amount Eamou is set to square the shape of the steel sheet.

The amount of edge to square the shape of the steel sheet is related to the rolled material and the rolling target dimension, and can be obtained by a conventional method or by using existing working data. You can use that value.

When the width spreading amount and the target edging amount are obtained as described above, the spreading target width TAWwd is obtained using the following equation (3).

TAWwd = ASWD-WDspr + Edrop. . . . . (3)

[Where, ASWD: rolling target width

Edrop: The value by which the width is reduced by edging (= Eamou × Heef (t, w))

Eamou: Target Edging Amount

Heef (t, w): Edging efficiency according to steel plate thickness (t) and width (w)]

The width of target width of warp width (TAWwd) should be added to the target width of rolling width by subtracting the amount of spreading during horizontal rolling after the width of width of width rolling is completed and the width reduced by edging.

However, even if edging is performed by the edger, since the width is recovered by horizontal rolling again, the value of the actual width should be reduced from the edging amount.

Therefore, since the width reduction amount is "edge amount-width recovery amount" and the edging efficiency is "width reduction amount / edging amount", the value Eamou whose width is reduced by actual edging becomes "edge amount x edging efficiency".

As described above, when the width of the bread width target is obtained, the width of the bread width target TATHwd 'for achieving the width width of the bread width is obtained using the following equation (4).

TATHwd '= SPTH × SPWD / TAWwd. . . . . (4)

Next, breading and rolling is performed to achieve the breading target thickness determined above.

After completion of the bake rolling, the edge roll gap for achieving the amount of edge is set, and then edging is performed.

Next, the actual edge roll gap and edging load performance are read to find the actual edging amount (AEamou) using the meter formula (5).

In this case, the edging amount is "plate width-post aging width" and the edging width is "(edge roll gap + edging load / edge density constant) x bow axis compensation coefficient", so the actual edging amount is "plate width-(edge roll gap + edge) Load / edge density constant) x bow axis correction coefficient ".

Therefore, the actual edging amount AEamou can be calculated | required by following formula (5).

AEamou = Wo- (ERG + ERF / EDM) x TF. . . . . (5)

[Wo: Wo: width before edging

ERG: Edge Roll Gap

ERF: Edging Load

EDM: Edger Mill Integer

TF: Linear Shrinkage Compensation Coefficient (= 1-1.35E-5 × Steel Plate Temperature)]

Next, horizontal rolling is performed by setting the roll gap of the horizontal rolling mill so that the thickness set in the normal horizontal rolling schedule is obtained, and then the width of the rolled material is measured.

Next, the recovery amount of the dog bone after aging is determined by taking into account the width measured by the width measuring device (MWID) and the width spread by horizontal rolling.

In this case, the width recovery amount is "width after horizontal rolling-width after edge width-width spreading during horizontal rolling" and the width after edge width is "width before aging-thread aging amount", so that the width recovery amount (WDrec) is represented by the following equation (6) Can be obtained by

WDrec = MWID-(Wo-AEamou)-(Ho-H1) x α. . . . . (6)

[Wo, Wo: width before edging

Ho: Thickness before horizontal rolling

H1: Thickness after horizontal rolling

α: width spreading coefficient]

Next, the real edging efficiency Meef is obtained by the following equation (7) using the width recovery amount WDrec and the real edging amount AEamou.

Meef = (AEamou-WDrec) / AEamou. . . . . (7)

When the actual edging efficiency Meef is obtained as described above, the corrected aging efficiency Heef is calculated by the following equation (8) using the actual aging efficiency Meef and the aging efficiency Hep (t, w) for the rolling material. (t, w) ')

Heef (t, w) '= Heef (t, w) + (Meef-Heef (t, w)) x G. . . . . (8)

[Here, Heef (t, w): edging efficiency that has been learned by thickness (t) and width (w) so far

Meef: Thread Edging Efficiency

G: Learning Gain]

If the learning gain is too large, hunting (hunting), if too small, the compensation of the error is insufficient.

Therefore, the value of the learning gain should be set appropriately, and the preferable learning gain is 0.35 to 0.60.

Next, after the even rolling of the next steel sheet, the width reduction amount due to edging (Edrop ') is applied to the even rolling material by using the corrected edging efficiency [Heef (t, w)' obtained as described above. To obtain.

Edrop '= Eamou x Heef (t, w)'. . . . . (9)

Next, when the above-described rolled rolled material is subjected to deburring rolling, the rolled sheet is rolled so that the width of the sum of the width of the deburring target width (TAWwd) and the width reduction amount (Edrop ') obtained by the edging as described above is obtained. The rolled material is rolled out.

Next, by edging and rolling horizontally the rolled rolled material as described above, a thick steel sheet having a better width degree is produced.

Since the corrected edging efficiency is greatly influenced by the thickness and width of the rolled material, it is desirable to obtain it through learning by thickness and width.

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

(Example)

The conventional method using edging efficiency as fixed value for each thickness and width of steel sheet in the range of product thickness: 6-50mm and product width: 1500-4500mm, and the present invention method for learning edging efficiency by width measurement results. The degree of exfoliation after rolling each was examined and the result is shown in FIG.

As shown in FIG. 5, it can be seen that, in the case of the present invention, the deviation is 7.25 mm, which is 2.38 mm smaller than the conventional method of 9.63 mm.

As described above, the present invention obtains a higher degree of edging efficiency by measuring the width of the rolled material after edging and horizontal rolling in the thick plate rolling process, and applies it to the next pass or the next rolled material, thereby reducing the edging width. It is possible to accurately predict the effect of improving the width more.

Claims (2)

In the method for manufacturing a post steel sheet using a thick plate rolling equipment comprising an edger and a horizontal rolling mill, which is a vertical rolling mill, Obtaining the target thickness (TATHwd) from the following equation (1) when the even rolling is finished; TATHwd = SPTH × SPWD / ASWD. . . . . (One) [Here, SPTH: thickness after even rolling SPWD: width after even rolling ASWD: Rolling Target Width] Obtaining a width spreading amount (WDspr) in the width direction at the time of horizontal rolling performed after the blasting rolling by using the following formula (2); WDspr = (TATHwd-ASTH) x α. . . . . (2) [Where, TATHwd: target thickness ASTH: Length Rolling Target Thickness α: width spreading coefficient] Calculating the width of target width (TAWwd) by using Equation (3) in consideration of the target edging amount and the amount of width spreading during horizontal rolling after the widthwise width obtained above; TAWwd = ASWD-WDspr + Edrop. . . . . (3) [Where, ASWD: rolling target width Edrop: The value by which the width is reduced by edging (= Eamou × Heef (t, w)) Eamou: Target Edging Amount Heef (t, w): Edging efficiency according to steel plate thickness (t) and width (w)] Obtaining a corrected width target width TATHwd 'for achieving the width target width TAWwd obtained as described above using Equation (4); TATHwd '= SPTH × SPWD / TAWwd. . . . . (4) Exposing the rolled rolled roll material; When the bake rolling is completed, the edge is set by the edge roll gap to achieve the edging amount, and then edging is performed, and the post-edge thread edging amount AEamou is obtained using Gauge Meter equation (5); AEamou = Wo- (ERG + ERF / EDM) x TF. . . . . (5) [Wo: Wo: width before edging ERG: Edge Roll Gap ERF: Edging Load EDM: Edger Mill Integer TF: Linear Shrinkage Compensation Coefficient (= 1-1.35E-5 × Steel Plate Temperature)] Rolling the edged rolled material horizontally and measuring a width MWID of the rolled material; Determining a recovery amount (WDrec) of the edging dogbone by the following equation (6) in consideration of the measurement width MWID and the width spreading amount due to horizontal rolling; WDrec = MWID-(Wo-AEamou)-(Ho-H1) x α. . . . . (6) [Wo, Wo: width before edging Ho: Thickness before horizontal rolling H1: Thickness after horizontal rolling α: width spreading coefficient] Obtaining a real edging efficiency Meef by the following equation (7) using the recovery amount WDrec and the actual edging amount AEamou obtained as described above; Meef = (AEamou-WDrec) / AEamou. . . . . (7) Obtaining a corrected edging efficiency [Heef (t, w) '] by the following equation (8) using the edging efficiency [Heef (t, w)] and the actual edging efficiency (Meef) for the rolled material described above; Heef (t, w) '= Heef (t, w) + (Meef-Heef (t, w)) x G. . . . . (8) [Here, Heef (t, w): edging efficiency that has been learned by thickness (t) and width (w) so far G: Learning Gain] After the even rolling of the next steel sheet, the width reduction amount (Edrop ') due to edging is performed on the even rolling material by using the correction edging efficiency [Heef (t, w)' obtained as described above by the following formula (9). Obtaining; Edrop '= Eamou x Heef (t, w)'. . . . . (9) During the deburring rolling of the even-rolled rolled material, deburring rolling so as to obtain a width of the sum of the defoamer target width (TAWwd) and the width reduction amount (Edrop ') due to edging; And Method of producing a steel sheet after the width is excellent, characterized in that it comprises a step of edging and horizontal rolling rolled rolled material as described above The method according to claim 1, wherein the width spreading coefficient α is 0.05 to 0.20 and the learning gain G is 0.35 to 0.60.