JP4608558B2 - Continuous casting method and continuous casting mold - Google Patents

Description

  The present invention relates to a continuous casting method and continuous casting mold for continuously casting molten metal.

  In continuous casting of molten metal such as steel, when molten metal is injected into the mold, the molten metal part in contact with the mold is solidified to form a solidified shell, which is pulled out below the mold, and then cooled secondary below the mold. Solidification proceeds in the band and finally a continuous cast slab is formed. The mold is formed of a water-cooled copper plate on the side in contact with the molten metal. In a continuous casting apparatus for casting a slab, it has two long-side mold plates and two short-side mold plates, and the width of the short-side mold plate is approximately equal to the thickness of a cast piece to be cast. The continuous casting mold is formed by assembling the two long side mold plates so as to sandwich the two short side mold plates.

  In the process of moving the solidified shell downward while solidification of the solidified shell proceeds in the mold, the solidified shell solidifies and contracts as solidification proceeds. Therefore, the solidified shell that has started solidification at the meniscus position of the molten metal in the mold contracts when it reaches the lower end of the mold, and the width and thickness of the slab during solidification are smaller than the meniscus position. . In slab continuous casting, since the width is wider than the thickness of the slab, the amount of solidification shrinkage in the slab width direction is large. If there is a gap between the mold and the solidified shell at the bottom of the mold due to the solidification shrinkage of the solidified shell, heat removal from the solidified shell to the mold will be hindered, and sufficient cooling of the mold will not be possible. The lost solidified shell will cause bulging to bulge outward.

  Therefore, a taper is provided at least on the short side of the mold. Providing the taper means that the distance between the lower ends of the mold is reduced with respect to the distance between the opposing short sides with respect to the distance at the meniscus position above the mold.

In the present invention, as shown in FIG. 1 (c), defines the upper and lower positions in the casting direction desired position, the distance between both short sides, W ₁ in the upper position, W ₂ in the lower position, the upper position Taper amount (%), taper rate (% / m), taper amount (%) = {(W ₁ −W ₂ ) / ΔL} × 100 (3)
Taper rate (% / m) = {(W ₁ −W ₂ ) / W ₀ / ΔL} × 100 (4)
And call it like this. Here, W ₀ may be anywhere as long as it has a fixed length according to a certain width. The upper end width of the mold and the lower end width of the mold can be used. Here, W ₀ (m) is defined as the meniscus width (W _M ).

  If the short side taper amount is too small, the contact between the solidified shell and the short side mold plate will be uneven, cooling imbalance will occur, the solidified shell growth will be uneven, the slab surface due to molten metal static pressure Cracking occurs. In particular, when the short side taper amount is smaller than the appropriate amount, in the thickness distribution of the solidified shell near the lower end of the mold, as shown in FIG. Longitudinal cracks are likely to occur on the slab surface corresponding to this part. In addition, when the short side taper amount is too large, the contact between the solidified shell and the short side mold plate becomes strong, excessive stress is applied to the solidified shell, and breakage of the solidified shell and breakout due to shell breakage occur. . Alternatively, the mold life may be reduced due to an increase in frictional force between the solidified shell and the mold.

  Regarding an appropriate short side taper, for example, in Patent Document 1, the short side taper rate βn is set to 0.7 to 1.3% / m.

  The surface (hereinafter also referred to as “taper surface 6”) of the conventional short-side mold plate 2 facing the solidified shell is processed in a plane from the upper part to the lower part as shown in FIG. However, the solidification shrinkage rate of the solidification shell is not constant at each position in the casting direction in the mold, and the solidification shrinkage rate is fast near the meniscus, and the solidification shrinkage rate becomes slower as it approaches the lower end of the mold. Therefore, it is considered that the surface of the solidified shell in contact with the short-side mold plate is not a flat surface but a curved surface in which the taper amount of the shell decreases as it goes below the mold.

  Patent Document 2 discloses a taper control method for controlling the taper of the mold short side as a curved surface. The short side mold is supported at at least three points on the back surface and deformed. A pressure device is attached to at least one of the three points, for example, the central portion, and the surface of the short side copper plate and the free contraction profile are matched in advance and during operation, so that more uniform heat removal is possible. By applying a force of 2 to 5 tons to the central load point, the maximum amount of deflection becomes 0.33 to 0.83 mm, which is considered to be a sufficient amount in view of the solidification shrinkage of the molten steel.

In Patent Document 3, the optimum short side taper is obtained by theoretical analysis. The optimum short side taper depends on the distance Z along the casting direction from the meniscus and the casting speed V, and the optimum taper rate (% / ^M ) is proportional to Z ^−1/2 and proportional to (4-V) (m / min). According to Example 1 and FIG. 2 of the same document, the short side of the mold having a cross-sectional dimension of 20.8 cm × 105 cm is formed into a shape having a three-step taper, and the taper rate is 2% / m, 0.7% / m, 0.4% / m. Further, according to Example 2 and FIG. 3, the short side of the mold having a cross-sectional dimension of 22 cm × 124 cm is formed into a shape having a three-step taper, and the taper rate is 4% / m, 1.3% / m,. 8% / m. In this way, a mold having a taper of two stages or three or more stages in the casting direction is called a multistage taper mold, and a short side mold plate having such a taper is called a multistage taper short side mold plate.

  Productivity can be improved, so that the casting speed of continuous casting is quick. Also in continuous casting of slabs, the casting speed has increased from around 2.0 m / min to about 3.0 m / min recently. In continuous casting using a multistage tapered short side mold plate, the optimum shape of the multistage tapered short side mold plate changes as the casting speed increases, and the casting method using the multistage tapered short side mold plate also changes. According to Patent Document 4, when the casting speed is increased, the degree of curvature of the multi-stage tapered short side mold plate is relaxed and the overall inclination is reduced.

  In continuous casting of slabs, cast slabs have various widths for each destination, so that the cast slab width is changed while continuous casting is continued. As shown in FIG. 7, the short-side mold plate 2 has a short-side driving device 4 for moving the short-side mold plate 2 in the long-side direction, and the short-side mold plate 2 is sandwiched between the long-side mold plates 3. By changing the position, the slab width can be changed during casting. That is, cast pieces having various widths can be cast using the same continuous casting mold 1 without exchanging both the long side mold plate 3 and the short side mold plate 2.

  Patent Documents 5 and 6 describe a method for estimating the solidification behavior of a slab in a mold by calculation. When the inclination of the casting direction of the mold or the casting speed is set to an arbitrary value, the thickness of the solidified shell at each part around the mold is calculated. Based on this result, the ratio between the maximum value and the minimum value of the solidified shell thickness at the lower end of the mold, the binding force between the solidified shell and the mold, and the gap amount can be obtained.

Japanese Patent Laid-Open No. 2005-21936 JP-A-2-247059 JP-A-56-53849 Japanese Patent Laid-Open No. 3-210953 JP 2006-346735 A JP 2006-346736 A

When continuous casting is performed using a multistage tapered short-side mold plate, the preferred curvature of the short-side mold plate decreases as the casting speed increases. Therefore, as the short side mold plate used for continuous casting where the maximum casting speed V _M (m / min) for casting is high, a short side plate formed by a short side taper with a small degree of curvature is used.

  In slab continuous casting, casting can be performed in accordance with various casting widths by using the same short side mold plate and changing the position of the short side mold plate in the mold. Casting slabs of various casting widths using a short side mold plate with a short side face with a small curvature corresponding to the high speed casting speed described above, good continuous casting was possible with narrow and intermediate widths. However, it has been found that there are cases where the effect of using a multi-stage taper short side mold plate cannot be fully exhibited during wide casting.

  In the present invention, in continuous casting using a multistage tapered short side mold plate, even if the maximum casting speed is high, the effect of the multistage tapered short side mold plate is exhibited at any casting width from narrow to wide. An object of the present invention is to provide a continuous casting method, a multistage tapered short side mold plate, and a continuous casting apparatus.

That is, the gist of the present invention is as follows.
(1) A continuous casting method using a multi-stage tapered short side mold plate having two or more tapers different in the casting direction, wherein the maximum casting speed for casting is V _M (m / min), and from the meniscus position to the casting direction. continuous casting method characterized in that the distance to the first tapered point of change and the change point position x (mm), the range as a function following (1) (2) of the x V _M.
50 ≦ x ≦ 300: V _M ≦ 2.5 (1)
50 ≦ x ≦ 300−200 (V _M −2.5): 2.5 <V _M ≦ 3.75 (2)
(2) The continuous casting method as described in (1) above, further casting a slab having a plurality of slab widths.
(3) The continuous casting method as described in (1) or (2) above, wherein the short side mold plate is a two-step tapered short side mold plate.
(4) A multistage tapered short side mold plate having two or more tapers different in the casting direction, which is used for continuous casting whose maximum casting speed is V _M (m / min), and is cast from the meniscus position to the casting direction. first the distance to the tapered point of change and the change point position x (mm), the following x as a function of V _M (1) (2) equation short sides of the continuous casting, characterized in that in the range of the Mold plate.
50 ≦ x ≦ 300: V _M ≦ 2.5 (1)
50 ≦ x ≦ 300−200 (V _M −2.5): 2.5 <V _M ≦ 3.75 (2)
(5) The short-side mold plate for continuous casting as described in (4) above, which is a two-step tapered short-side mold plate.
(6) It has a long side mold plate 3 and a multistage tapered short side mold plate 2 having two or more tapers different in the casting direction, and the maximum casting speed for casting is V _M (m / min). The distance from the meniscus position of the taper short side mold plate 2 to the first taper change point in the casting direction is the change point position x (mm), and x is a function of V _M within the range of the following formulas (1) and (2): A continuous casting mold characterized by:
50 ≦ x ≦ 300: V _M ≦ 2.5 (1)
50 ≦ x ≦ 300−200 (V _M −2.5): 2.5 <V _M ≦ 3.75 (2)
(7) The continuous casting mold according to (6), wherein the short side mold plate 2 is a two-step tapered short side mold plate.

  In the present invention, in continuous casting using a multistage tapered short side mold plate, as the maximum casting speed increases, the taper change point position from the meniscus is shortened, so that the solidification level in a wide casting width range from narrow to wide. It is possible to maintain the binding force at once and in a favorable range.

In the present invention, the maximum casting speed for casting is V _M (m / min), and the distance from the meniscus position of the multistage tapered short side mold plate to the first taper changing point in the casting direction is the changing point position x (mm). .

In the present invention, the total taper rate T _T , the upper taper rate T _U , the lower taper rate T _L , and the vertical taper ratio are defined as follows.

When the distance between the short sides is W _M (m) at the meniscus position, W _B (m) at the lower end of the mold, and L (m) from the meniscus position to the lower end of the mold (FIGS. 1A and 1B) )), And the total taper rate T _T (% / m) T _T (% / m) = {(W _M −W _B ) / W _M / L} × 100 (5)
It is defined as

W in the tapered surface 6 _U on the casting direction at the top of the multistage tapered short side mold plate, optionally define the upper and lower positions, the distance between the short sides, in W ₁ (m), the lower position at the upper position ₂ (m), when the distance from the upper position to the lower position is ΔL (m) (FIGS. 1A and 1B), the upper taper ratio T _U (% / m) is set to T _U (% / m) = {(W ₁ −W ₂ ) / W _M / ΔL} × 100 (6)
It is defined as

On the lower taper surface 6 _{L at} the bottom in the casting direction of the multi-stage tapered short side mold plate, an upper position and a lower position are arbitrarily determined, and the distance between both short sides is set to W ₃ (m) at the upper position and W at the lower position. ₄ (m), when the distance from the upper position to the lower position is ΔL (m) (FIGS. 1A and 1B), the lower taper rate T _L (% / m) is set to T _L (% / m) = {(W ₃ −W ₄ ) / W _M / ΔL} × 100 (7)
It is defined as

Vertical taper ratio is
Vertical taper ratio = upper taper ratio / lower taper ratio = T _U / T _L (8)
It is defined as

  Patent Documents 5 and 6 describe a method for estimating the solidification behavior of a slab in a mold by calculation. When the inclination of the casting direction of the mold or the casting speed is set to an arbitrary value, the thickness of the solidified shell at each part around the mold is calculated as shown in FIG. Based on this result, the ratio B / A between the maximum value A and the minimum value B of the solidified shell thickness at the lower end of the mold, the binding force between the solidified shell and the mold, and the gap amount can be obtained.

  Using the calculation methods described in Patent Documents 5 and 6, the shape of the solidified shell at the lower end of the mold and the binding force between the solidified shell and the mold were determined for continuous casting using a multistage tapered short side mold plate. The shape of the solidified shell at the lower end of the mold is derived as shown in FIG. 8 by calculation. A portion with a thin solidified shell thickness may be formed on the long side of the solidified shell in the vicinity of the slab corner, and the solidified shell thickness at this portion can be set to the minimum value B of the shell thickness. The ratio B / A between the maximum value A and the minimum value B of the solidified shell thickness is referred to herein as “solidification uniformity”. When casting with good solidification uniformity is performed, the shell thickness of the portion where the shell thickness is thin on the long side near the corner approaches the shell thickness of other thick portions.

  Actually casting the molten steel, adding S to the molten steel in the mold during casting, and evaluating the thickness distribution of the solidified shell at the lower end position of the mold by sulfur printing of the slab after solidification. It was found that the uniformity was in good agreement with the maximum and minimum ratios of the mold bottom solidified shell thickness obtained from sulfur printing. Therefore, it is possible to find a suitable continuous casting method using the solidification uniformity obtained by calculation as an index.

  If the value of solidification uniformity (B / A) obtained by calculation is 0.7 or more, good solidification uniformity can be ensured even in actual casting. If the constraint force obtained by calculation (the standard value at each width (value normalized by the constraint force when the taper rate is 1.0% / m with a one-step taper) is 2.0 or less, even in actual casting It is possible to perform good casting with less restraint, and by setting the solidification uniformity (B / A) and restraint force within the above preferred ranges, it is actually possible that breakout does not occur when continuous casting is performed. This is confirmed by the results of continuous casting.

  Hereinafter, the solidification uniformity and restraint force are calculated by the calculation method based on the above-mentioned Patent Documents 5 and 6 (hereinafter also referred to as “calculation method of the present invention”), and the optimum shape of the multistage tapered short side mold plate is examined. I decided to.

In a conventional multi-stage tapered short side mold plate, particularly a two-step tapered short side mold plate, the distance L from the meniscus position to the lower end of the mold is about 900 mm, and the change point position x is about 300 mm. When the maximum casting speed V _M to adopt casting speed of up to about 2.5 m / min, adopts 4.0 degree taper as a vertical taper ratio, good casting both coagulation uniformity and binding Could be realized. This point can be confirmed by the calculation method of the present invention.

  The casting width is 1100 mm (narrow width), the total taper rate is 1.6% / m, the change point position x of the two-step taper short side mold plate is 300 mm constant, and the casting speed is 1.0 to 3.0 m / min. The bending condition of the short side mold plate was changed by changing the vertical taper ratio of the two-step taper short side mold plate, and the solidification uniformity and the binding force were calculated by the calculation method of the present invention.

  As shown in FIG. 2, if the taper ratio is the same, the solidification uniformity improves as the casting speed increases, but the binding force also increases. It can be seen that it is preferable to lower the vertical taper ratio as the casting speed increases in order to keep both the solidification uniformity and the restraining force within a good range. When the upper and lower taper ratio range in which both the solidification uniformity and the restraining force can be satisfactorily maintained are examined for each casting speed, the upper and lower taper ratio preferable range is 5.0 or less and the casting speed is 2 at a casting speed of 2.0 m / min. The result showed that the preferable range of the upper and lower taper ratio was 4.0 or less at 0.5 m / min, and the preferable range of the upper and lower taper ratio was 3.0 or less at the casting speed of 3.0 m / min.

  Next, the shape of a short side mold plate having a casting width of 1100 mm and good solidification uniformity and restraining force (a mold shape having an up / down taper ratio of 3.0 optimized for a casting speed in the range of 3.0 m / min) The casting width was as wide as 2200 mm. When changing the width, the total taper ratio was kept at 1.6% / m. As a result, the width was 2200 mm and the up / down taper ratio was 1.7.

  When the solidification uniformity and restraint force were calculated for the casting width of 2200 mm (wide) by the calculation method of the present invention, the casting speed was 3.0 m / in when the slab width was widened while keeping the total taper constant. It was found that at min, the preferred range of the vertical taper ratio was reduced to less than 1.7 and the solidification uniformity was also reduced (FIG. 3). That is, it was found that in a mold optimized for high-speed casting up to a casting speed of 3.0 m / min at a width of 1100 mm, if the casting width was 2200 mm, it was out of the optimum range.

  Therefore, when the multi-step taper is optimized for each casting speed in the width of 1100 mm, the change is not made by fixing the change point position x and changing the vertical taper ratio but by keeping the vertical taper ratio constant at 4.0. I tried changing the point position x. The total taper rate was 1.6% / m, the change point position x was changed, and the solidification uniformity and the binding force were calculated by the calculation method of the present invention. The result is shown in FIG. When the casting speed was 2.5 m / min or less, the change point position preferred range was 300 mm or less, and when the casting speed was 3.0 m / min, the change point position preferred range was 200 mm or less.

  Next, using a short side mold plate having a change point position x suitable for a width of 1100 mm (a mold shape with a change point position of 200 mm optimized up to a casting speed range of 3.0 m / min), a width of 2200 mm The calculation in casting was performed. When the total taper ratio was maintained at 1.6% / m and the slab width was widened with the total taper constant, the vertical taper ratio was 2.5 at the cast width of 2200 mm. Therefore, in the 2200 mm width, the total taper rate is set to 1.6% / m, and the vertical taper ratio is kept constant at 2.5 as described above, and the change point position x is changed by the calculation method of the present invention. The calculation result of solidification uniformity and binding force is shown (FIG. 5). As is apparent from FIG. 5, it was found that if the change point position x is 200 mm or less, a good range can be secured at a casting speed of 3.0 m / min or less even if the casting width is 2200 mm. Accordingly, when casting at a maximum casting speed of 3.0 m / min, continuous casting can be performed satisfactorily if the displacement point position is 200 mm or less.

  Similarly, at a casting speed of 3.75 m / min, if the change point position x is 50 mm or less, good casting can be performed at any of the width 1200 mm (FIG. 4) and the width 2200 mm (FIG. 5). . Therefore, when casting at a maximum casting speed of 3.75 m / min, if the displacement point position is 50 mm or less, continuous casting can be performed satisfactorily.

  As described above, the change point position x is changed when compared with a suitable upper limit taper ratio when applied to a wide width by using a mold that is optimized by changing the vertical ratio at each casting speed and changing the vertical taper ratio at the time of narrow width. When using a mold that has been optimized, it is possible to increase the preferred vertical taper ratio, and when changing the change point position x, it is more suitable for wide width than for narrow width. However, it was found that the solidification uniformity increased conversely although the vertical taper ratio decreased.

  That is, when determining the optimum taper shape of the multi-stage tapered short side mold plate when the casting speed becomes high, as shown in FIGS. 4 and 5, the change point position x is raised upward as the casting speed becomes higher. Thus, it was found that better solidification uniformity and restraint force can be maintained even when the casting width is wider than when the vertical taper ratio is changed.

  Incidentally, the relationship between FIG. 4 and FIG. 5 has also been confirmed by calculation and actual machine tests to show the same relationship in the range of 600 mm to 2500 mm, which is the slab width assumed from an industrial viewpoint.

From the relationship of FIG. 4 and FIG. 5, the solidification uniformity is 0.7 or more, expressed in equation conditions restraining force is preferably a range of 2.0 or less as a variable of maximum casting speed V _M, the following ( 1) It is derived as shown in equation (2).
50 ≦ x ≦ 300: V _M ≦ 2.5 (1)
50 ≦ x ≦ 300−200 (V _M −2.5): 2.5 <V _M ≦ 3.75 (2)

The reason why the lower limit of x is set to 50 mm is that if the position of the change point is further above the mold, the effect of the multi-stage taper cannot be obtained sufficiently, and the normal single-stage taper is hardly affected. From the above (2), V _M is a solution eliminates exceeds 3.75 m / min. That is, the upper limit of V _M in the present invention is 3.75 m / min. Also, the upper limit of x is set to 300 mm because when the upper and lower taper ratio is to be secured above a certain value, when the upper strong taper region becomes longer, the taper rate of the lower taper portion becomes smaller and the total taper rate is constant and the width is increased. This is because when the width is reduced and the casting is narrow, the lower taper ratio becomes extremely small, and it tends to become a reverse taper (expands as the taper goes down), which easily causes trouble that the slab bulges at the bottom of the mold. .

The present invention, the effect is remarkable as the maximum casting speed V _M is increased. Maximum casting speed V _M can exhibit particularly remarkable effects in the high-speed casting of 2.5 m / min greater.

  Next, using the same two-step taper short side mold plate (mold having a change point position of 200 mm) as above, the casting speed is fixed at 1.5 m / min, the casting width is fixed at 1100 mm, and the total taper ratio is changed to solidify. Uniformity and binding force were calculated. The slab thickness was 240 mm. The results are shown in FIG. As is clear from the figure, the solidification uniformity can be maintained well if the total taper rate is 0.5% / m or more. Further, if the total taper rate is 2.0% / m or less, the restraining force is small, and it can be held well.

  As the multi-stage tapered short side mold plate used in the present invention, a mold plate having a taper of three or more stages may be used, but as a result of setting the change point position upward, the two-stage tapered short side mold plate is sufficient. The effect can be exhibited.

  In the present invention, the cast slab thickness is preferably 220 mm to 300 mm, more preferably 240 mm to 300 mm. When the slab thickness exceeds 300 mm, excessive equipment is required as a continuous casting mold for changing the width during casting, which is substantially difficult to realize. If the casting thickness is less than 240 mm, the diameter of the immersion nozzle for injecting the molten metal from the tundish must be reduced, so that uniform injection of the molten metal becomes difficult. When the casting thickness is less than 220 mm, more uniform injection becomes more difficult.

  Based on FIG. 7, a continuous casting mold for realizing the casting method of the present invention will be described.

  The continuous casting mold 1 of the present invention includes a long-side mold plate 3 and a multistage tapered short-side mold plate 2 having two or more short-side taper ratios (unit:% / m) different in the casting direction. The long-side mold plate 3 and the short-side mold plate 2 are each composed of a pair, and the side facing the solidified shell is preferably a water-cooled copper plate, and the opposite surface is a steel back frame. The width of the short side mold plate 2 is substantially equal to the thickness of the cast piece to be cast. By sandwiching the short side mold plate 2 between the two long side mold plates 3, a mold having a rectangular casting space is formed.

When the maximum casting speed for casting with this continuous casting mold is V _M (m / min), the distance from the meniscus position of the multistage tapered short side mold plate 2 to the first taper changing point in the casting direction is changed to the changing point position x ( and mm), following the x as a function of V _M (1) (2) in the range equation. This makes it possible to maintain both the solidification uniformity and the restraining force in a favorable range in a wide casting width range from a narrow width to a wide width.
50 ≦ x ≦ 300: V _M ≦ 2.5 (1)
50 ≦ x ≦ 300−200 (V _M −2.5): 2.5 <V _M ≦ 3.75 (2)

  The continuous casting mold 1 of the present invention further includes a short side driving device 4 capable of changing the width of the cast slab and the inclination of the short side, and a control device 5 for the short side driving device. The taper ratio at the uppermost short side in the casting direction is the upper taper ratio, the taper ratio at the lowermost side is the lower taper ratio, and the taper ratio at the short side surface connecting the meniscus part and the lower end of the mold with a straight line is the total taper ratio. The value obtained by dividing the upper taper rate by the lower taper rate is defined as the upper and lower taper ratio, which is the same as in the continuous casting method of the present invention.

  The control device 5 of the short side drive device drives the short side mold plate so that the same total taper ratio is obtained in any slab width during casting, and the vertical taper ratio is 4 or less in any slab width. Control is preferable as a practical operation mode.

  The short-side drive device 4 has, for example, two upper and lower drive actuators 9 and holds the short-side mold plate 2 by the actuator 9 from the back frame side. By determining the position of the short-side mold plate by the movement of the upper and lower actuators 9, the total taper ratio of the short-side mold plate 2 can be set to a predetermined value for each casting width. As the actuator 9, an electric cylinder, a hydraulic cylinder, or the like can be used. Or it is good also as an apparatus which has a drive means which performs a reciprocating motion and a swing motion of a short side mold plate as a short side drive device.

  In addition, when changing the casting width during continuous casting, it is required to continuously change the casting width while performing normal casting. During such a width change, it is necessary to change the total taper rate to perform a smooth width change, and the total taper rate cannot be kept constant.

  Since the continuous casting mold of the present invention has a minimum castable slab width of 1100 mm or less and a maximum castable slab width of 2200 mm or more, a slab having a wide range can be cast. preferable. The minimum castable slab width is preferably 800 mm or less. The minimum castable slab width is practically 600 mm. The maximum castable slab width is realistic 2500 mm.

It is a figure explaining the taper surface of a short side mold plate, (a) is a 2 step taper short side mold plate, (b) is a 3 step taper short side mold plate, (c) is a 1 step taper short side mold plate. FIG. It is a figure which shows the change of a solidification uniformity and a restraint force when a vertical taper ratio and a casting speed are changed in slab width of 1100 mm. It is a figure which shows the change of a solidification uniformity and a restraint force when changing up and down taper ratio and casting speed in slab width 2200mm. It is a figure which shows the change of solidification uniformity and restraint force when changing point position x and a casting speed are changed in slab width of 1100 mm. It is a figure which shows the change of the solidification uniformity and restraint force when changing the change point position x and casting speed in slab width 2200mm. It is a figure which shows the change of the coagulation | solidification uniformity when a total taper rate is changed, and restraint force. It is a figure which shows the continuous casting mold of this invention, (a) is a top view, (b) is a cross-sectional front view. It is a figure which shows the solidification shell shape in the casting_mold | template lower end calculated | required.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Continuous casting mold 2 Short side mold plate 3 Long side mold plate 4 Short side drive device 5 Control device 6 Tapered surface 9 Actuator 10 Solidified shell 11 Meniscus position

Claims (7)

A continuous casting method using a multistage tapered short side mold plate having two or more tapers different in casting direction,
The maximum casting speed to cast a V _M (m / min), following the distance to the first tapered point of change and the change point position x (mm) from the meniscus position in the casting direction, the x as a function of V _M (1) (2) A continuous casting method characterized by being within the range of the formula.
50 ≦ x ≦ 300: V _M ≦ 2.5 (1)
50 ≦ x ≦ 300−200 (V _M −2.5): 2.5 <V _M ≦ 3.75 (2)   The continuous casting method according to claim 1, further comprising casting a slab having a plurality of slab widths.   The continuous casting method according to claim 1 or 2, wherein the short side mold plate is a two-step tapered short side mold plate. A multi-stage tapered short side mold plate used for continuous casting in which the maximum casting speed for casting is V _M (m / min) and having two or more tapers different in the casting direction,
Continuous the distance from the meniscus position to the first taper transition points in the casting direction by the change point position x (mm), the following x as a function of V _M (1) (2), characterized in that in the range type Short side mold plate for casting.
50 ≦ x ≦ 300: V _M ≦ 2.5 (1)
50 ≦ x ≦ 300−200 (V _M −2.5): 2.5 <V _M ≦ 3.75 (2)   The short-side mold plate for continuous casting according to claim 4, which is a two-step tapered short-side template plate. Having a long side mold plate and a multi-stage tapered short side mold plate having two or more tapers different in the casting direction, and the maximum casting speed for casting is V _M (m / min);
Wherein the multi-stage tapered short side mold plate of the change point position the distance from the meniscus position to the first taper transition points in the casting direction x (mm), the following x as a function of V _M (1) (2) within formula A continuous casting mold characterized by that.
50 ≦ x ≦ 300: V _M ≦ 2.5 (1)
50 ≦ x ≦ 300−200 (V _M −2.5): 2.5 <V _M ≦ 3.75 (2)   The continuous casting mold according to claim 6, wherein the short side mold plate is a two-step tapered short side mold plate.

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