JPH11179508A - Slab width change method in steel continuous casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely conduct change control of a short side width by conducting each control based on a specified numerical formula, in the cases of changing the width while adjusting an inclination of a short side, changing while maintaining an inclination of a short side and changing while returning an inclination of a short side to a normal casting state, respectively. SOLUTION: Change control is conducted based on formulas 1, 2 when changing the width while adjusting an inclination of the short side, formulas 3, 4 when changing while maintaining the inclination and formulas 5, 6 when changing while returning the inclination to a normal casting state. In the formulas, WU is mold upper end width, WL is mold lower end width, WU1 is mold upper end width before width change, WU2 is mold upper end width after width change, WL1 is mold lower end width before width change, WL2 is mold lower end width after width change, (all of the above units are mm), α is mold width taper rate (%/m), P is max width rate (%/m), L is mold length (m), X1 ,2 is molding length at finishing step 1, 3, (m), and ΔWU1 and ΔWL1 are mold upper and lower end width changing amounts in step 1, respectively (mm).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of changing the width of a slab by moving a short side of a mold during continuous casting in continuous casting of steel.

[0002]

2. Description of the Related Art In recent years, in continuous casting of steel, a continuous casting method of changing a slab width without stopping casting has been carried out from the viewpoint of improving productivity and yield. Then, it has become very important to change the width during continuous casting in order to efficiently directly connect the continuous casting process and the rolling process. Therefore, in recent years, various proposals have been made on a width changing method during continuous casting.

For example, in Japanese Patent Application Laid-Open No. 4-41061, a short side reference position with respect to a casting length is determined in advance, and a width moving speed is suppressed based on a deviation amount of an actual width position. In particular, there are proposals for obtaining a slab having a target shape.

[0004] In Japanese Patent Application Laid-Open No. 61-144255,
There has been proposed a method of changing the width by setting the maximum moving speed of the short side from the rolling conditions and controlling the moving speed of the short side based on the maximum moving speed.

[0005]

However, in both of the above proposed methods, since the object to be finally controlled is the moving speed of the short side, the control formula of the movement is complicated, and the casting method is required when the width is changed. One-sided error occurred. Therefore, a new function of correcting the width moving speed is required in order to make the width dimension planned in advance.

[0006] In addition, in the above proposed method, when an attempt is made to satisfy the constraints of the conditions in the rolling process,
Since the restriction is temporarily replaced with the restriction on the moving speed on the short side, extra work is required.

The present invention provides a slab width changing method in a continuous steel casting method capable of solving the above-mentioned conventional problems by controlling the change of the short side width based on the width pattern with respect to the casting length. It is intended to be.

[0008]

According to the present invention, in order to achieve the above object, in the present invention, the width is changed while adjusting the inclination of the short side, and the width is changed while maintaining the constant inclination of the short side. Step 2, which changes the width while returning the inclination of the short side to the steady casting state, and changing the width in each of the three steps.
It is to be controlled as a function of the casting length. In this way, the constraint based on the conditions in the rolling process can be used directly as a function of the width change amount.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The slab width changing method in the continuous casting method of steel according to the present invention is characterized in that the shorter side of the mold is moved during continuous casting of steel to increase or decrease the width of the slab. Step 1 of changing the width while adjusting the inclination, Step 2 of changing the width while keeping the short side at a constant inclination, Step 3 of changing the width while returning the inclination of the short side to the steady casting state The width is changed in each step and the width is changed in each step based on the following equation (1).

[0010]

## EQU1 ## Step 1: W _U = W _U1 − (3/4) ｛P / (2L) ^3/2 ｝ (X ^4/3 ) W _L = W _L1 − (1/32) · (P / L ³⁾ · X ⁴ step _{2: W U = W U1 -} △ W U1 -P (X-X 1) W L = W L1 - △ W L1 -P (X-X 1) step 3: W _U = W _U2 + (1/32) [1 / ｛α / 100 (W _L2 −W _L1 ) + P
｝ ³ · L ³ ] × ｛P (X ₃ -X)] ⁴ W _L = W _L2 + (3/4) ・ / 1 / (2L) ^3/2 ｝ [1 / ｛α / 100 (W _L2
−W _L1 ) + P｝ ^1/3 × {P (X ₃ −X)] ^4/3 where W _U1 = {1+ (α / 100) L} · W _L1 W _U2 = {1+ (α / 100) L｝ · W _L2 ΔW _U1 = (3/2) · P · L ΔW _U3 = (1/2) [α / 100 (W _L2 −W _L1 ) + P] L ΔW _U2 = (W _U1 −W _U2 )-△ W _U1- △ W _U3 LW _L1 = (）) ・ P ・ L ＷW _L3 = (3/2) [α / 100 (W _L2 -W _L1 ) + P] L ＷW _L2 = _{(W L1 -W L2) - △} W L1 - △ W L3 X 1 = 2L X 2 = X 1 + △ W U2 / P = X 1 + △ W L2 / P X 3 = X 2 +2 [alpha / 100 { (W _L2 −W _L1 ) / P｝ +1]
L W _U: template upper width (mm) W _L: template bottom width (mm) W _U1: width before changing the mold upper end width (mm) W _U2: mold upper width after width changing (mm) W _L1: Width changing Front mold bottom width (mm) _WL2 : Mold bottom width after width change (mm) α: Mold width taper rate (% / m) P: Maximum width change rate (1 / m) L: Mold length (m) X ₁ : Cast length at the end of step 1 (m) X ₂ : Cast length at the end of step 2 (m) X ₃ : Cast length at the end of step 3 (m) ΔW _U1 : at step 1 Change amount of upper end width of mold (mm) ΔW _U2 : Change amount of upper end width of mold in step 2 (mm) ΔW _U3 : Change amount of upper end width of mold in step 3 (mm) ΔW _L1 : Change amount of lower end width of mold in step 1 (Mm) ΔW _L2 : Change amount of lower end width of mold in step 2 (mm) △ W _L3 : Change amount of lower end width of mold in step 3 (mm)

In the above-described method for changing the slab width in the continuous casting method for steel according to the present invention, the conventional method for changing the slab width when the short side of the mold is moved during the continuous casting to change the slab width is shorter. While the moving speed of the side was controlled, the width (position) of the short side itself was defined as a function of the length of the slab, as shown in the above-described formula 1, and according to the formula 1, the width was changed every moment. Is controlled as a function of the pouring length, so that when the width change rate P per unit length of the slab is restricted from the conditions in the rolling process, the restriction is directly substituted into Expression 1. Can be.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for changing a slab width in a continuous casting method for steel according to the present invention will be described with reference to an embodiment shown in FIGS. FIG. 1 is a schematic perspective view of a continuous casting machine to which the slab width changing method in the continuous casting method of steel according to the present invention is applied, FIG. 2 is a view taken along the line AA in FIG. 1, and FIG. Flowchart of slab width changing method in continuous casting method of FIG.
FIG. 5 is a conceptual diagram of a width change by a slab width changing method in a continuous casting method of steel according to the present invention, and FIG. 5 shows an embodiment of a width change by a slab width changing method in a continuous casting method of steel according to the present invention. FIG.

1 and 2, reference numeral 1 denotes a long side of the mold;
Is the mold short side, and the mold short side 2 is clamped by the mold long side 1 to define the mold width. When changing the width of the mold, the drive device 3 moves the pair of mold short sides 2 into and out of contact with each other.

The slab width changing method in the continuous casting method of steel according to the present invention is carried out by using a continuous casting machine having the above-described mold, and will be described below with reference to FIGS. I do.

When changing the width of the slab during continuous casting, first, the width change condition, the casting speed, and the width change amount are input, and if the width change amount is within the range that can be rolled in the downstream rolling process. Determine whether or not. Then, if rolling is possible, the maximum width change rate P at which rolling is possible and the pouring speed Vm are calculated. On the other hand, if rolling is not possible, the maximum width change rate P at which rolling is possible is calculated from the maximum casting speed max.

Next, the maximum width change rate P determined as described above is calculated by the steps 1, 2, 3 shown in the above-mentioned equation (1).
It is determined whether or not the above calculated casting speed Vm can be maintained. Then, the maximum width change rate P is determined in step 1,
If the pouring speed Vm calculated in Steps 2 and 3 can be maintained, the width change amounts △ W _U1 , △ W _U2 , △ W _U3 , △ W _L1 , △ in the upper and lower ends of the mold in Steps 1, 2 and 3.
W _L2, △ and W _L3, calculates the maximum width change rate P, and width sort pattern from speed Vm casting. On the other hand, if the maximum width change rate P cannot maintain the pouring speed Vm calculated in steps 1, 2, and 3, the maximum width change rate P is reduced to an appropriate value, and the casting speed Vm is determined again. The width change pattern is calculated as described above.

After calculating the width change pattern, for example, as shown in FIG. 4, feedback control is performed along the width change pattern while changing the positions of the upper end of the mold and the lower end of the mold at steps 1, 2 and 3. And change the width.

Incidentally, a slab having a thickness of 90 mm and a width of 1233 mm, which had been continuously cast at a top end width of 1257 mm, a bottom end width of 1246 mm and a casting speed of 4 m / min, was cast at a casting speed of 2 m / min. Assuming that the maximum width change rate P is 1.23% / m, the upper end width of the mold is finally changed to 1235 mm and the lower end width to 1225 mm by the slab width changing method in the continuous casting method of steel according to the present invention. FIG. 5 shows a change pattern of the casting width with respect to the casting length based on Equation 1 when the width of the slab is changed to 1233 mm.

When the short side width is changed in the pattern shown in FIG. 5, the error from the target width profile is 1
Within mm, the slab width could be changed without any problem.

[0020]

As described above, according to the present invention,
The width (position) of the short side itself is controlled as a function of the casting length according to a mathematical formula that defines the width (position) itself as a function of the length of the slab, so that the desired width can be obtained with high accuracy. it can. In addition, even when restricting the width change rate P per unit length of the slab from the conditions in the rolling process, the constraint can be directly substituted into the equation, so that any operating condition can be changed in a short time. Can be done.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a continuous casting machine to which a slab width changing method in a continuous casting method of steel according to the present invention is applied.

FIG. 2 is a view taken on line AA of FIG. 1;

FIG. 3 is a flowchart of a slab width changing method in the continuous casting method of steel according to the present invention.

FIG. 4 is a conceptual diagram of a width change by a slab width changing method in the continuous casting method of steel according to the present invention.

FIG. 5 is a view showing one embodiment of a width change by a slab width changing method in the continuous casting method of steel according to the present invention.

[Explanation of symbols]

 2 Mold short side 3 Drive unit

Claims (1)

[Claims] When the width of a slab is enlarged or reduced by moving the short side of a mold during continuous casting of steel, the width of the short side is adjusted while adjusting the inclination of the short side. The width is changed in three stages of changing the width while maintaining the width in step 2 and changing the width of the short side while returning the inclination of the short side to the steady casting state. A slab width changing method in a continuous casting method for steel, which is performed based on the following formula. Step _{1: W U = W U1 -} (3/4) {P / (2L) 3/2} (X 4/3) W L = W L1 - (1/32) · (P / L 3) · X ⁴ step _{2: W U = W U1 -} △ W U1 -P (X-X 1) W L = W L1 - △ W L1 -P (X-X 1) step _{3: W U = W U2 +} (1 / 32) [1 / ｛α / 100 (W _L2 -W _L1 ) + P
｝ ³ · L ³ ] × ｛P (X ₃ -X)] ⁴ W _L = W _L2 + (3/4) ・ / 1 / (2L) ^3/2 ｝ [1 / ｛α / 100 (W _{L2
^{-W L1) + P} 1/3 ×}} {P (X 3 -X) ] ^4/3 where, W _U: template upper width (mm) W _L: template bottom width (mm) W _U1: width changing previous Mold upper end width (mm) W _U2 : Mold upper end width after width change (mm) _WL1 : Mold lower end width before width change (mm) _WL2 : Mold lower end width after width change (mm) α: Mold width taper Rate (% / m) P: Maximum width change rate (1 / m) L: Mold length (m) X ₁ : Cast length at the end of step 1 (m) X ₃ : Cast length at the end of step 3 (M) ΔW _U1 : Change amount of upper end width of mold in step 1 (mm) ΔW _L1 : Change amount of lower end width of mold in step 1 (mm)