JP2021171805A - Refractory for continuous casting - Google Patents

Abstract

To provide a refractory for continuous casting capable of effectively preventing alumina deposition over the whole circumference of a molten steel flow passage and also suppressing the damage of the refractory.SOLUTION: At least one of a first flow passage part 11a, a second flow passage part 12a, a third flow passage part 13a, and an opening part 22 has a porous part 31, the side that does not face the flow passage part(s) or the opening part 22 of the porous part 31 faces a gas pool 32, the first flow passage part 11a or the like are respectively divided into a first region and a second region, in at least one of the first flow passage part 11a or the like having the porous part 31, the thickness of the porous part 31 is d0 at the maximum, in 80% or higher of a prescribed region involving a region having a deflection angle of 0±15°, a ratio between the d0 and the thickness d1 of the porous part 31, d1/d0 is 0.2 to 0.8, and, in the whole region of the second region, a ratio between the d0 and the thickness d2 of the porous part 31, d2/d0 is higher than 0.8.SELECTED DRAWING: Figure 1

Description

The present invention relates to a refractory for continuous casting having a gas blowing function.

In continuous casting of molten metal, a nozzle-shaped refractory provided with a flow rate controlling means such as a slide valve is widely used in order to control the flow rate of the molten metal. In the portion provided with such a flow rate control means, the structure of the flow path is more complicated than that in the simply tubular portion, so that the flow velocity of the molten metal differs depending on the portion in the flow path. At this time, there is a problem that the alumina in the molten metal easily adheres to the wall surface of the flow path in the portion where the flow velocity of the molten metal is slow.

As a countermeasure against alumina adhesion, a method of selectively blowing gas into the part where stagnation of molten steel occurs in the nozzle (Patent Document 1) and a method of blowing gas to the side where the flow velocity of molten steel is high to keep the gas in the molten steel flow with good yield. Therefore, a method for promoting floating separation of inclusions in a tundish (Patent Document 2) is disclosed. Further, the structure has a structure in which the number of through pores per unit area on the opposite side of the gas supply pipe to the nozzle is larger than that on the gas supply pipe side (Patent Document 3), and the thickness of the gas pool is opposite to that of the gas introduction pipe attachment portion. A structure widened toward the side (Patent Document 4) is also disclosed.

Japanese Unexamined Patent Publication No. 2003-320443 Japanese Unexamined Patent Publication No. 2018-161663 Microfilm of Jitsugyo No. 63-075060 (Jitsukaihei No. 1-177056) Microfilm of Jitsugyo No. 62-197294 (Jitsukaihei No. 1-105066)

As disclosed in Patent Document 1, it is known that a large amount of alumina adheres to a portion where the flow velocity of molten steel is slow. However, depending on the structure in which the gas is blown only into a specific range of the nozzle flow path as in the techniques of Patent Documents 1 and 2, it is not possible to sufficiently prevent the adhesion of alumina in the portion where the gas is not blown.

Further, Patent Document 3 discloses a structure in which the number of through pores per unit area on the opposite side of the gas supply pipe is larger than that on the gas supply pipe side, but the amount of alumina adhered is biased depending on the sliding direction of the sliding nozzle plate. It did not solve the phenomenon. In addition, since the through pores are straight tubes, the bubble size is large and the number of bubbles is small, so that the effect of preventing alumina adhesion is limited.

Further, in the technique of Patent Document 4, the thickness of the gas pool is widened toward the opposite side of the gas introduction pipe attachment portion, but as in the technique of Patent Document 3, the amount of alumina attached depends on the sliding direction of the sliding nozzle plate. It did not solve the phenomenon of bias.

Therefore, an object to be solved by the present invention is to provide a refractory for continuous casting that can effectively prevent the adhesion of alumina over the entire circumference of the molten steel flow path and suppress damage to the refractory.

As a result of repeating various experiments, the present inventors have found that the gas flow rate can be controlled by changing the thickness of the porous refractory. Then, by reducing the thickness of the porous refractory in the portion where the molten steel flow velocity is slow and increasing the thickness of the porous refractory on the opposite side, a relatively large amount of gas is applied to the portion where the molten steel flow velocity is slow. We succeeded in supplying a relatively small amount of gas to the part where the flow velocity of molten steel is high. As a result, it was discovered that by adjusting the thickness of the porous refractory according to the different alumina adhesion for each part, alumina adhesion can be prevented over the entire circumference of the molten steel flow path.

The present invention has been completed with further studies based on the above findings. According to the present invention, the following refractories for continuous casting are provided.

The first refractory material for continuous casting according to the present invention is a refractory material for continuous casting capable of flowing molten steel, and has an upper nozzle having a first flow path portion, a fixing plate having a second flow path portion, and a third flow. A lower nozzle having a path portion and a sliding plate having an opening and a plate-like portion are provided, and the fixing plate has the first flow path portion and the second flow at the downstream end portion of the first flow path portion. The sliding plate and the lower nozzle are provided so as to communicate with the road portion in a fluid manner, and the sliding plate and the lower nozzle are provided so as to be integrally slidable with respect to the fixed plate, where the sliding plate and the lower nozzle are provided. Is a communication posture in which the second flow path portion, the third flow path portion, and the opening are fluid-communication, and a closing posture in which the plate-shaped portion closes the downstream end portion of the second flow path portion. The first flow path portion, the second flow path portion, the third flow path portion, and at least one of the openings are the entire circumference of the flow path portion or the opening. The side of the porous portion that faces the gas pool facing the gas supply source and the fluid communicating with the gas supply source, the first flow path portion, and the first The two flow paths, the third flow path, and the opening are divided into a first region and a second region, respectively, and the first flow path and the second flow path are the molten steel. In a polar coordinate system in which the center of the flow path portion in the cross section orthogonal to the distribution direction of is set as the origin and the sliding direction is 0 ° when the posture is changed from the closed posture to the communicating posture, the deviation angle is The region of 0 ° ± 120 ° is the first region, the region of deviation angle of 180 ° ± 60 ° is the second region, and the molten steel flow in the opening and the third flow path. In a polar coordinate system in which the center of the opening in a cross section orthogonal to the direction is the origin and the sliding direction is 0 ° when the posture is changed from the communicating posture to the closed posture, the deviation is 0 ° ±. The region of 120 ° is the first region, the region of deviation angle of 180 ° ± 60 ° is the second region, and the first flow path portion and the second flow path portion are provided with the porous portion. , And at least one of the third flow path portion and the opening, the thickness of the porous portion in the direction orthogonal to the flow direction of the molten steel is d ₀ at the maximum, and the first Of the regions, in 80% or more of the predetermined region including the region having the deviation angle of 0 ° ± 15 °, the ratio d of _{d 0 to the thickness d 1} of the porous portion facing the first region d ₁ / d ₀ is 0.2 or more and 0.8 or less, before In the entire region of the serial second region, and d _0, the ratio d _{2 /} d ₀ of the thickness d ₂ of the porous portion facing the second region may be greater than 0.8.

The second refractory material for continuous casting according to the present invention is a refractory material for continuous casting capable of flowing molten steel, and has an upper nozzle having a first flow path portion, a fixing plate having a second flow path portion, and a first. A lower nozzle having a three flow path portion, a seal board having a fourth flow path portion, and a sliding board having an opening and a plate-like portion are provided, and the fixing board is a downstream end of the first flow path portion. The first flow path portion and the second flow path portion are provided so as to communicate with each other in the portion, and the seal board is provided at the upstream end portion of the third flow path portion with the third flow path portion and the first flow path portion. The sliding board is provided so as to communicate with the four flow paths, and the sliding board has a communication posture in which the second flow path, the fourth flow path, and the opening communicate with each other, and the second flow. The plate-shaped portion is slidable with respect to the fixing plate and the sealing plate over a closed posture in which the plate-shaped portion is inserted between the road portion and the fourth flow path portion, and the first flow path portion, the said. At least one of the second flow path portion, the third flow path portion, the fourth flow path portion, and the opening includes the flow path portion or a porous portion facing the entire circumference of the opening. The side of the porous portion that does not face the flow path portion or the opening faces the gas pool that communicates with the gas supply source, and the first flow path portion, the second flow path portion, and the third flow path portion. The flow path portion, the fourth flow path portion, and the opening are divided into a first region and a second region, respectively, and the first flow path portion, the second flow path portion, and the third flow path are provided. With respect to the portion and the fourth flow path portion, the center of the flow path portion in the cross section orthogonal to the flow direction of the molten steel is set as the origin, and the sliding direction when the posture is changed from the closed posture to the communication posture. In the polar coordinate system in which the deviation angle is 0 °, the region where the deviation angle is 0 ° ± 120 ° is the first region, the region where the deviation angle is 180 ° ± 60 ° is the second region, and the opening. In a polar coordinate system in which the center of the opening in a cross section orthogonal to the flow direction of the molten steel is the origin, and the sliding direction when changing the posture from the communicating posture to the closed posture is a deviation angle of 0 °. The region having a deviation angle of 0 ° ± 120 ° is the first region, the region having a deviation angle of 180 ° ± 60 ° is the second region, and the first flow path portion including the porous portion. , The thickness of the porous portion in at least one of the second flow path portion, the third flow path portion, the fourth flow path portion, and the opening in the direction orthogonal to the flow direction of the molten steel. _{Is d 0} at the maximum, and includes a region having a deviation angle of 0 ° ± 15 ° in the first region. That at least 80% of a given area, and _{d 0,} the ratio _d 1 / _{d 0} of the thickness _{d 1} of the porous portion facing the first region is 0.2 to 0.8, in the entire region of the second region, and d _0, the ratio d _{2 /} d ₀ of the thickness d ₂ of the porous portion facing the second region may be greater than 0.8.

According to these configurations, the adhesion of alumina can be effectively prevented over the entire circumference of the molten steel flow path, and damage to the nozzle can be suppressed.

Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited by the preferred embodiments described below.

In the refractory for continuous casting according to the present invention, the 50% pore diameter of the porous portion by the mercury press-fitting method is preferably 5 μm or more and 200 μm or less.

According to this configuration, a sufficient gas flow rate can be obtained, so that it is easier to prevent the adhesion of alumina. In addition, appropriate corrosion resistance can be easily obtained.

In the refractory for continuous casting according to the present invention, the length of the porous portion along the flow direction of the molten steel is preferably 5 mm or more.

According to this configuration, a sufficient gas flow rate can be obtained, so that it is easier to prevent the adhesion of alumina.

The refractory material for continuous casting according to the present invention has a thickness of 0.5 mm or more in the direction away from the flow path portion of the gas pool, and a length of the gas pool along the flow direction of the molten steel. It is preferably 5 mm or more.

According to this configuration, a sufficient gas flow rate can be obtained, so that it is easier to prevent the adhesion of alumina.

In the refractory material for continuous casting according to the present invention, the distance from the intermediate portion of the sliding board in the length along the flow direction of the molten steel is the distance between the opening in the direction along the flow direction of the molten steel. It is preferable that at least a part of the gas pool is provided in a region which is 3 times or less the maximum width in the direction orthogonal to the flow direction of the molten steel.

According to this configuration, a sufficient gas flow rate can be obtained in a region where the adhesion of alumina is particularly likely to be a problem, so that it is easier to prevent the adhesion of alumina.

Further features and advantages of the present invention will be further clarified by the following illustration of exemplary and non-limiting embodiments described with reference to the drawings.

It is a front sectional view which shows the use state of the nozzle for continuous casting which concerns on 1st Embodiment. It is a front sectional view which showed the state which the sliding disk is in a communicating posture of the nozzle for continuous casting which concerns on 1st Embodiment. It is a front sectional view which shows the state which the sliding disk is in a closed posture of the nozzle for continuous casting which concerns on 1st Embodiment. FIG. 3 is a top sectional view taken along line IV-IV of FIG. It is a top sectional view in line VV of FIG. It is a front sectional view which shows the use state of the nozzle for continuous casting which concerns on 2nd Embodiment. It is a top sectional view which shows the other embodiment of the sectional shape of a porous part. It is a top sectional view which shows the other embodiment of the sectional shape of a porous part. It is a top sectional view which shows the other embodiment of the sectional shape of a porous part. It is a front sectional view which shows the other embodiment of a gas pool. It is a front sectional view which shows the other embodiment of a gas pool.

[First Embodiment]
The first embodiment of the refractory for continuous casting according to the present invention will be described with reference to the drawings. Hereinafter, an example in which the refractory material for continuous casting according to the present invention is applied to a nozzle 100 for continuous casting (FIG. 1) for pouring molten steel discharged from a tundish (not shown) into a mold (not shown) will be described. ..

(Basic configuration of nozzle for continuous casting)
The continuous casting nozzle 100 according to the present embodiment includes an upper nozzle 11, a fixing plate 12, a lower nozzle 13, and a sliding plate 20 (FIG. 1). The continuous casting nozzle 100 is provided on the lower side of the tundish. Therefore, the molten steel discharged from the tundish moves downward due to gravity and is poured into the mold via the continuous casting nozzle 100. Although the details will be described later, in the continuous casting nozzle 100, a slide gate device capable of controlling the flow of molten steel by sliding the sliding plate 20 is formed. The lower nozzle is not only the one attached to the lower part of the slide gate device, but also the name including the immersion nozzle whose lower end is inserted into the mold.

Unless otherwise specified, the vertical direction in the following description represents the vertical direction in FIG. Further, the horizontal direction in the following description represents the left-right direction in FIG. 1 unless otherwise specified.

The upper nozzle 11 is a cylindrical body connected to the lower side of the tundish. The upper nozzle 11 is provided with a conical trapezoidal cylindrical first flow path portion 11a whose diameter is reduced from the upper side to the lower side as a flow path for molten steel. Here, the term "flow path portion" refers to a portion in which a space portion that functions as a flow path for molten steel and a wall surface portion that defines the space portion are combined. In the present embodiment, the inner diameter of the first flow path portion 11a is 150 mm at the upper part and 75 mm at the lower part.

The fixing plate 12 is a substantially plate-like body fixed to the lower end of the upper nozzle 11 (downstream side in the flow direction of molten steel). The fixed plate 12 is provided with a cylindrical second flow path portion 12a that penetrates the fixed plate 12. Here, the diameter (75 mm) of the circle in the horizontal cross section of the second flow path portion 12a coincides with the diameter of the circle in the horizontal cross section at the lower end portion of the first flow path portion 11a. Further, the fixing plate 12 is aligned so that the cross sections of the upper end portion of the second flow path portion 12a and the lower end portion of the first flow path portion 11a coincide with each other. That is, the second flow path portion 12a communicates with the first flow path portion 11a in a fluid manner. The inner diameters of the upper end portion of the second flow path portion 12a and the lower end portion of the first flow path portion 11a do not necessarily have to be the same. It is not uncommon to combine different inner diameters within a range that does not cause extreme turbulence in the molten steel flow due to equipment and operational factors, and the present invention can exert its effect even in such a case.

The lower nozzle 13 is a bottomed cylindrical body provided on the lower side of the fixing plate 12. A sliding plate 20 described later is slidably attached between the lower nozzle 13 and the fixing plate 12. The lower nozzle 13 is provided with a third flow path portion 13a as a flow path for molten steel, and the lower nozzle slides integrally with the sliding plate. In the present embodiment, the inner diameter of the third flow path portion 13a is 75 mm. Further, a discharge hole portion 13b is provided at the lower end portion of the lower nozzle 13, and the molten steel discharged from the tundish is discharged from the discharge hole portion 13b and poured into the mold.

The sliding plate 20 is a plate slidably attached to the fixed plate 12 on the lower side of the fixed plate 12 (downstream side of the fixed plate 12) and on the upper side of the lower nozzle 13 (upstream side of the lower nozzle 13). It is a state. As described above, the sliding plate and the lower nozzle slide together. The sliding board 20 has a structure in which the plate-shaped portion 21 is provided with a cylindrical opening 22 penetrating the sliding board 20. Here, the diameter (75 mm) of the horizontal cross-sectional circle of the opening 22 coincides with the diameter of the horizontal cross-sectional circle of the second flow path portion 12a. The length of the sliding plate 20 along the vertical direction (flow direction of molten steel) is 40 mm.

More specifically, the sliding board 20 can slide in the left-right direction (horizontal direction) of FIG. FIG. 2 shows a state in which the sliding plate 20 is aligned so that the cross sections of the lower end portion of the second flow path portion 12a and the upper end portion of the opening 22 match. The posture of the sliding board 20 shown in FIG. 2 is referred to as a communication posture 20A. Further, in FIG. 3, a plate-shaped portion 21 of the sliding board 20 is inserted between the second flow path portion 12a and the third flow path portion 13a, whereby the second flow path portion 12a is closed. Indicates the state of The posture of the sliding board 20 shown in FIG. 3 is referred to as a closed posture 20B. In this way, the sliding board 20 can slide over the communication posture 20A and the closed posture 20B.

As shown in FIG. 1, the continuous casting nozzle 100 is also used in a state where the sliding plate 20 is in a position between the communicating posture 20A and the closed posture 20B. That is, when the continuous casting nozzle 100 is used, the sliding plate 20 may be at an arbitrary position between the communication posture 20A and the closing posture 20B (including the communication posture 20A and the closing posture 20B). By appropriately changing the position of the sliding plate 20 in this way, the flow rate of the molten steel discharged through the continuous casting nozzle 100 can be adjusted.

In the following description, the expressions of the communication posture 20A side (right side in FIG. 1) and the closed posture 20B side (left side in FIG. 1) may be used in the horizontal direction.

The upper nozzle 11, the fixing plate 12, the lower nozzle 13, and the sliding plate 20 are all made of refractory material. As the refractory material used here, a dense refractory material conventionally applied to a nozzle for continuous casting can be used except for a portion related to the gas supply mechanism 30 described later. As the refractory material, a refractory material commonly used in the art can be used, and as the base material thereof, it is generally used as a refractory material such as alumina, mullite, spinel, magnesia, and zirconia. Examples of various materials such as oxide-based materials and materials in which these oxides and non-oxides such as carbon are combined can be exemplified.

(First region and second region of the flow path)
Next, the "first region" and the "second region" of the first flow path portion 11a, the second flow path portion 12a, the third flow path portion 13a, and the opening 22 are defined. In the following description, first, the positioning of the first region and the second region will be described, and then specific positions will be specified.

The first region is a region where the flow velocity of the molten steel is relatively slow in each of the first flow path portion 11a, the second flow path portion 12a, the third flow path portion 13a, and the opening 22. For example, in the usage state shown in FIG. 1, the flow velocity of the molten steel is blocked by the sliding plate 20 on the communication posture 20A side (right side of FIG. 1) of the first flow path portion 11a and the second flow path portion 12a. Is relatively slow. Further, since the closing posture 20B side (left side in FIG. 1) of the opening 22 and the third flow path portion 13a is a portion deviated from the main flow of the molten steel, the flow velocity of the molten steel becomes slow. Therefore, the first region is a region where alumina adhesion is relatively likely to occur.

On the other hand, the second region is a region in which the flow velocity of the molten steel is relatively high in each of the first flow path portion 11a, the second flow path portion 12a, the third flow path portion 13a, and the opening 22. For example, in the usage state shown in FIG. 1, the first flow path portion 11a and the second flow path portion 12a are closed on the 20B side (left side in FIG. 1), and the opening 22 and the third flow path portion 13a are on the communication posture 20A side (on the left side in FIG. 1). In FIG. 1 (right side), since an obstacle-free flow path is formed in the vertical direction, the flow velocity of the molten steel is relatively high. Therefore, the second region is a region where alumina adhesion is relatively unlikely to occur.

The cross-sectional shape of the first flow path portion 11a of the upper nozzle 11 in the cross section is a circle having a diameter of 75 mm. Since the left-right direction of FIG. 4 and the left-right direction of FIG. 1 are the same, the right side of FIG. 4 is the communication posture 20A side, and the left side of FIG. 4 is the closed posture 20B side. Here, with respect to the position of each part in the cross section shown in FIG. 4 (cross section orthogonal to the flow direction of the molten steel), the direction from the closed posture 20B to the communication posture 20A is declined with the center C1 of the first flow path portion 11a as the origin. Set the polar coordinate system to be 0 °. Then, in the above polar coordinate system, the region having a declination of 0 ° ± 120 ° is defined as the first region 111, and the region having the declination of 180 ° ± 60 ° is defined as the second region 112. The first region and the second region are similarly defined for the second flow path portion 12a.

The cross-sectional shape of the sliding board 20 in the VV cross section (FIGS. 1 and 5) is substantially square, and the cross-sectional shape of the opening 22 in the cross section is a circle having a diameter of 75 mm. Here, with respect to the position of each part in the cross section shown in FIG. 5 (cross section orthogonal to the flow direction of the molten steel), the declination angle 0 ° in the direction from the communication posture 20A to the closing posture 20B with the center C2 of the opening 22 as the origin. Set the polar coordinate system to be. Then, in the above polar coordinate system, the region having a declination of 0 ° ± 120 ° is defined as the first region 201, and the region having the declination of 180 ° ± 60 ° is defined as the second region 202. The first region and the second region are similarly defined for the third flow path portion 13a.

(Gas supply mechanism)
Next, the gas supply mechanism 30 provided in the continuous casting nozzle 100 according to the present embodiment will be described. In this embodiment, an example in which the gas supply mechanism 30 is provided on the upper nozzle 11, the fixing plate 12, the lower nozzle 13, and the sliding plate 20 will be described.

The gas supply mechanism 30 according to the present embodiment faces the entire circumference of the wall surface portion of the portion through which the molten steel flows (first flow path portion 11a, second flow path portion 12a, third flow path portion 13a, and opening 22). 31 of the porous portion, a gas pool 32 provided so as to face the side of the porous portion 31 not facing the flow path portion, and a gas supply portion (not shown) for fluid communication with the gas pool 32. , (Figs. 1 and 4). In the following description, the gas supply mechanism 30 (FIG. 4) provided in the first flow path portion 11a will be particularly described, but unless otherwise specified, the second flow path portion 12a, the third flow path portion 13a, and the third flow path portion 13a, as well. The same description holds true for the gas supply mechanism 30 provided in the opening 22.

As the refractory material constituting the porous portion 31, the porous refractory material used for the gas blowing port in the conventional continuous casting nozzle can be applied. Here, the porous refractory refers to a refractory having an apparent porosity of 10% or more measured by the method of JIS R 2205: 1992, and the base material thereof is alumina, mullite, spinel, and the like. Examples of various materials such as oxide-based materials generally used as refractories such as magnesia and zirconia and materials combining them with non-oxides such as carbon can be exemplified.

The pore diameter of the refractory material constituting the porous portion 31 is preferably a 50% pore diameter of 5 μm or more and 200 μm or less by the mercury intrusion method. If the 50% pore diameter is less than 5 μm, the gas blowing resistance is large and the gas flow rate is unlikely to increase, so that the adhesion of alumina may not be sufficiently prevented. Further, if the 50% pore diameter exceeds 200 μm, the corrosion resistance may decrease.

The porous portion 31 is provided so as to face the entire circumference of the wall surface portion of the first flow path portion 11a. As shown in FIG. 4, the cross-sectional shape of the porous portion 31 is a shape in which a part located on the communication posture 20A side is cut off by a straight line from the annular shape surrounding the first flow path portion 11a. The thickness d ₁ of the porous portion 31 has a minimum value of 12.5 mm at the position where the declination is 0 °, and the declination is 0 in the region where the declination is 0 ° ± 37 ° (a part of the first region 111). The thickness of the porous portion 31 gradually increases as the distance from the ° position increases. Then, in the remaining region (a part of the first region 111 and the entire area of the second region 112), the thickness d ₂ of the porous portion 31 has a maximum value of 25.0 mm. In this shape, in the first region 111, d ₁ / d ₀ of 0.2 or more and 0.8 or less is the entire range of the declination of 0 ± 29.6 ° (0 ± 15 ° or more). Range). The minimum value of d ₁ / d ₀ is 0.50 (or more than 0.2). _{Further, d 2} / d ₀ is 1.0 (greater than 0.8) in the entire second region 112.

Similarly, the second flow path portion 12a, the third flow path portion 13a, and the porous portion 31 provided in the opening 22 are also thin in the portion facing the first region of each flow path portion. It is thickly constructed in the portion facing the two regions. However, with respect to the opening 22 and the third flow path portion 13a, since the declination angle 0 ° is defined in a direction 180 ° different from that of the first flow path portion 11a and the second flow path portion 12a, the first region 201 Note that the horizontal arrangement of the second region 202 and the second region 202 is reversed from that of the other flow paths (FIG. 5).

The gas pool 32 is provided on the side of the porous portion 31 that does not face the first flow path portion 11a. The gas pool 32 is a flow path through which the inert gas supplied from the gas supply unit (not shown) can flow. The thickness of the gas pool 32 in the direction away from the first flow path portion 11a is a constant 4 mm over the entire circumference thereof. In the present embodiment, the surface of the gas pool 32 that does not face the porous portion 31 faces the dense refractory. The outer circumference of the gas pool 32 may be circular in order to facilitate the production of the nozzle refractory. Since the amount of gas supplied to the flow path portion is determined by the thickness of the porous portion, the difference in thickness in the direction away from the flow path portion of the gas pool does not affect the practice of the present invention.

The porous portion 31 and the gas pool 32 in the upper nozzle 11 are provided in a region where the vertical distance from the lower end of the first flow path portion 11a of the upper nozzle 11 is 20 mm to 30 mm. Therefore, the length of the porous portion 31 and the gas pool 32 along the vertical direction (flow direction of molten steel) is 10 mm. Although not shown, a shrinkable heat-resistant packing having a thickness of about 0.5 to 3.0 mm is usually mounted between the upper nozzle and the fixing plate to improve the sealing property. In the embodiment, the heat-resistant packing has a thickness of 1.5 mm. Note that this thickness is a value in a contracted state during operation. The length of the fixed plate along the vertical direction is 40 mm, the diameter of the circle in the horizontal cross section of the opening 22 provided in the sliding plate 20 is 75 mm, and the length of the sliding plate 20 along the vertical direction is 35 mm. Therefore, the porous portion 31 and the gas pool 32 have a distance from the intermediate portion in the vertical direction of the sliding plate 20 in the vertical direction of 95 mm to 105 mm (1.27 of the diameter of the opening 22). It can be said that it is provided in the area of (double to 1.40 times).

The inert gas supplied from the gas supply unit is blown into the first flow path portion 11a from the gas pool 32 through the pores of the porous portion 31, thereby preventing the adhesion of alumina on the wall surface of the first flow path portion 11a. Will be done.

According to the gas supply mechanism 30, the porous portion 31 is thinly formed in the first region (region where alumina adhesion is relatively easy to occur), and porous in the second region (region where alumina adhesion is relatively unlikely to occur). The quality portion 31 is thickly constructed. As a result, it is possible to supply a certain amount or more of the inert gas over the entire circumference of the portion through which the molten steel flows (first flow path portion 11a, second flow path portion 12a, third flow path portion 13a, or opening 22). Moreover, since more inert gas can be supplied to the region where alumina adhesion is relatively likely to occur, alumina adhesion can be effectively prevented over the entire circumference of the flow path portion.

[Second Embodiment]
A second embodiment of the refractory for continuous casting according to the present invention will be described with reference to the drawings. Hereinafter, an example in which the refractory material for continuous casting according to the present invention is applied to a nozzle 200 (FIG. 6) for continuous casting for pouring molten steel discharged from a tundish into a mold will be described. The same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The continuous casting nozzle 200 according to the present embodiment further includes a sealing plate 14 in addition to the upper nozzle 11, the fixing plate 12, the lower nozzle 13, and the sliding plate 20 described in the first embodiment (FIG. 6). Compared with the continuous casting nozzle 100 according to the first embodiment, it can be said that the structure is such that the sealing plate 14 is added between the sliding plate 20 and the lower nozzle 13.

The seal board 14 is a substantially plate-like body fixed to the lower side of the sliding board 20 (downstream side of the sliding board 20). Here, the positions of the seal plate 14 relative to the upper nozzle 11 and the fixing plate 12 are fixed. The seal board 14 is provided with a cylindrical fourth flow path portion 14a that penetrates the seal board 14. Here, the diameter (75 mm) of the horizontal cross-sectional circle of the fourth flow path portion 14a coincides with the diameter of the horizontal cross-sectional circle of the second flow path portion 12a and the opening 22. Further, the seal board 14 is aligned so that the fourth flow path portion 14a coincides with the extension line of the second flow path portion 12a. Unlike the case of the first embodiment, the lower nozzle 13 does not slide integrally with the sliding plate, but is fixed to the lower end of the seal plate 14, and the upper nozzle 11 is fixed. The relative positions with respect to the plate 12 and the seal plate 14 are fixed.

With the above configuration of the seal board 14, the sliding board 20 is slidable with respect to the fixing board 12 and the seal board 14. Further, when the sliding board 20 is in the communication posture 20A, the lower end portion of the opening 22 and the upper end portion of the fourth flow path portion 14a are aligned so that the cross sections match.

Further, the fourth flow path portion 14a is provided with a gas supply mechanism 30 similar to that described in the first embodiment. In the second embodiment, the first region and the second region in the third flow path portion 13a and the fourth flow path portion 14a are defined in the same manner as the first flow path portion 11a and the second flow path portion 12a. That is, with respect to the third flow path portion 13a and the fourth flow path portion 14a, the polar coordinates with the center of the cross-sectional circle of the fourth flow path portion 14a as the origin and the direction from the closed posture 20B to the communication posture 20A as an argument 0 °. A system is set, and a region having a declination of 0 ° ± 120 ° is defined as a first region and a region having a declination of 180 ° ± 60 ° is defined as a second region in the polar coordinate system. It should be noted that the definitions of the first region and the second region in the third flow path portion 13a are different between the first embodiment and the second embodiment.

[Other Embodiments]
Finally, other embodiments of the refractory for continuous casting according to the present invention will be described. The configurations disclosed in each of the following embodiments can be applied in combination with the configurations disclosed in other embodiments as long as there is no contradiction.

In the above embodiment, a configuration in which the gas supply mechanism 30 is provided in all the members constituting the continuous casting nozzles 100 and 200 has been described as an example. However, in the refractory for continuous casting according to the present invention, the porous portion and the gas pool may be provided only in a part of the constituent members. That is, in a refractory material for continuous casting provided with an upper nozzle, a fixed plate, a lower nozzle, and a sliding plate, at least one of the upper nozzle, the fixed plate, the lower nozzle, and the sliding plate has a porous portion and a gas pool. As long as it is provided, the number of members provided with the porous portion and the gas pool is not limited. Similarly, in a fireproof material for continuous casting having an upper nozzle, a fixing plate, a lower nozzle, a sealing plate, and a sliding plate, at least one of the upper nozzle, the fixing plate, the lower nozzle, the sealing plate, and the sliding plate is used. As long as the porous portion and the gas pool are provided, the number of members provided with the porous portion and the gas pool is not limited. Further, a plurality of porous portions and a gas pool may be provided on the same member. When a plurality of porous portions are provided, it is not necessary that all the porous portions are provided with a non-uniform thickness, and the porous members provided with a non-uniform thickness are uniformly or uniformly provided. A porous member provided with a thickness close to the above may be used in combination.

In the above embodiment, a configuration in which d ₁ / d _{0 of} the first region 111 is 0.2 or more and 0.8 or less is the entire region within the range of the declination of 0 ± 29.6 ° will be described as an example. bottom. As in this example, in the present invention, in the present invention, a predetermined region including a region in which the flow velocity of the molten steel is particularly slow, that is, a region having a declination of 0 ± 15 ° (in the above example, the declination is 0 ± 29.6). In the region of °. In 80% or more of 111a in FIG. 4 and 201a in FIG. 5, d ₁ / d ₀ may be a suitable value (that is, 0.2 or more and 0.8 or less). The _{region where d 1} / d ₀ takes a suitable value (hereinafter referred to as a thin-walled region) is more preferably 90% or more, and further preferably 95% or more of the predetermined region. Further, _{the preferable value of d 1} / d ₀ is more preferably 0.2 or more and 0.7 or less, and further preferably 0.2 or more and 0.6 or less.

Conversely, there may be an exception region of less than 20%, that is _{, a region where d 1} / d ₀ exceeds a suitable value in the predetermined region. The number of exception regions may be one or plural as long as the total number of exception regions is less than 20% of the entire region. However, the exception region is preferably sandwiched between thin-walled regions. The thin-walled region sandwiching the exception region more preferably exists over a width of 1 ° of declination, and more preferably exists over a width of 3 ° of declination. Even in the exception region, it is preferable that there is no region where _{d 1} / d _{0 is less than the preferable value.} This is because if such a region exists, excess gas circulates in the region and there is a shortage of gas circulated in other regions.

In the above embodiment, the configuration in which d ₂ / d ₀ is 1.0 in the entire area of the second region 112 has been described as an example. As in this example, in the present invention, d ₂ / d ₀ may be a value larger than 0.8 in the entire second region. Here, if there is a region where d ₂ / d ₀ is 0.8 or less in the second region, excess gas circulates in the region, so that the gas circulated in the first region becomes insufficient. Therefore, in such a case, the effect of preventing the adhesion of alumina in the first region may not be sufficiently obtained. It is more preferable that _{d 2} / d ₀ is larger than 0.9 in the entire second region.

In the above embodiment, an example will be described in which the cross-sectional shape of the porous portion 31 is a shape in which a part located on the communication posture 20A side is cut off by a straight line from an annular shape surrounding the first flow path portion 11a. _{However, the cross-sectional shape of the porous portion is such that d 1} / d ₀ is 0.2 or more in at least 80% of the predetermined region including the range of the deviation angle of 0 ° ± 15 ° in the first region. It is 0.8 or less, and is not limited as long as _{d 2} / d _{0 is larger than 0.8 in the entire second region.} For example, a part of the circle is cut off by a plurality of straight lines (Fig. 7), a part of the diameter of the circle is shortened (Fig. 8), and the circle is offset from the center of the opening (Fig. 9). can. In addition, in order to help understanding, the same reference numerals as those in FIG. 4 are attached in FIGS. 7 to 9. In addition, FIG. 7 also shows an exception region 111b.

In the above embodiment, an example in which a refractory having a porosity of 10% or more measured by the method of JIS R2205: 1992 is used as the refractory constituting the porous portion 31 has been described. The refractory material constituting the porous portion was measured by the method of JIS R2205: 1992 (boiling method, vacuum method) or a method equivalent thereto (ASTM C20-00 (2015), ASTM C830-00 (2016), etc.). The porosity is preferably 10% or more and 50% or less, and more preferably 10% or more and 40% or less.

In the above embodiment, it has been described that the pore diameter of the refractory material constituting the porous portion 31 is preferably 50 μm or more and 200 μm or less by the mercury injection method. The pore diameter is more preferably 100 μm or less, and further preferably 50 μm or less.

In the above embodiment, an example in which the length of the porous portion 31 and the gas pool 32 along the vertical direction is 10 mm has been described. The length of the porous portion and the gas pool along the flow direction of the molten steel is preferably 5 mm or more. When the length is 5 mm or more, sufficient gas permeation ability can be easily obtained. The length is more preferably 10 mm or more, and further preferably 15 mm or more. The upper limit of the length is not particularly limited, and for example, a porous portion and a gas pool may be provided over the entire length of the molten steel flow path provided in the nozzle for continuous casting. Further, the lengths of the porous portion and the gas pool may be the same or different. For example, a gas pool shorter than the porous portion may be used. In this case, a part of the porous portion on the side not facing the molten steel flow path faces a dense refractory or a metal casing material. Conversely, a gas pool longer than the porous portion may be used. At this time, the portion having neither the gas pool nor the porous portion is not included in the "length along the vertical direction of the porous portion 31 and the gas pool 32".

In the above embodiment, an example in which the thickness of the gas pool 32 in the direction away from the first flow path portion 11a is 4 mm has been described. The thickness in the direction away from the flow path portion of the gas pool is preferably 0.5 mm or more. When the thickness is 0.5 mm or more, sufficient gas supply capacity can be easily obtained. The thickness is more preferably 0.7 mm or more, and further preferably 1 mm or more. Further, the upper limit of the thickness is not particularly limited.

In the above embodiment, the configuration in which the surface of the gas pool 32 that does not face the porous portion 31 faces the dense refractory is described as an example. However, in the present invention, the material in contact with the surface of the gas pool on the side not facing the porous portion is a superporous material having extremely high gas permeability as compared with the porous portion, for example, the apparent porosity is higher than 50%. , 50% Porosity is larger than 200 μm (these are not preferable because they cause gas leaks), and are not particularly limited. In addition to the dense fireproof materials exemplified above, porous fireproof materials and metal casing materials Or, the surface thereof may be sealed to prevent gas permeation. FIG. 10 shows an example in which the surface of the gas pool 32 that does not face the porous portion 31 faces the metal casing material provided on the outside of the upper nozzle 11 without passing through a dense refractory material. Shown.

In the above embodiment, the porous portion 31 of the upper nozzle 11 has a vertical separation distance of 95 mm to 105 mm (1.27 of the diameter of the opening 22) from the vertical intermediate portion of the sliding plate 20 in the vertical direction. The configuration provided in the region of (times to 1.40 times) has been described as an example. In the present invention, the distance from the intermediate portion of the length along the molten steel distribution direction in the sliding board in the direction along the molten steel distribution direction is the maximum width of the opening in the direction orthogonal to the molten steel distribution direction. It is preferable that at least a part of the gas pool is provided in the region which is 3 times or less of the above, and more preferably 50% or more of the length of the gas pool along the flow direction of the molten steel is provided. It is more preferable that 100% of the length of the gas pool along the distribution direction of the gas pool is provided. Further, even in the region, a porous member having a uniform or nearly uniform thickness between the gas pool and the molten steel flow path may be used in combination, but the combined use is the length of the gas pool along the flow direction of the molten steel. It is preferably 50% or less, and more preferably 25% or less of the length of the gas pool along the flow direction of the molten steel. The region defined above is a region in the vicinity of the sliding plate, and the difference in the flow velocity of the molten steel between the first region and the second region is particularly large (hereinafter, referred to as a region in the vicinity of the sliding plate). Therefore, the adhesion of alumina is particularly likely to occur in the region near the sliding board. Therefore, if at least a part of the gas pool is provided in the region near the sliding plate, the gas can be surely blown into the region near the sliding plate, and the adhesion of alumina can be preferably prevented. When a plurality of porous portions and gas pools are provided, at least a part of the gas pool may be provided in the region near the sliding board for at least one set of the porous portions and the gas pool. For example, in the example shown in FIG. 11, pairs of the porous portion 31 and the gas pool 32 are provided at two locations in the vertical direction of the upper nozzle 11, but only the lower pair is in the vicinity of the sliding board. It is provided in the area. If necessary, a porous member having a uniform or nearly uniform thickness between the gas pool and the molten steel flow path may be used in combination outside the region near the sliding board.

It should be understood that with respect to other configurations, the embodiments disclosed herein are exemplary in all respects and the scope of the invention is not limited thereto. Those skilled in the art will be able to easily understand that modifications can be made as appropriate without departing from the spirit of the present invention. Therefore, another embodiment modified without departing from the spirit of the present invention is naturally included in the scope of the present invention.

Hereinafter, the present invention will be further described with reference to examples. However, the following examples do not limit the present invention.

[Creation of nozzle for continuous casting]
(Examples 1 to 4)
Continuous casting nozzles having various upper nozzles with different shapes of porous portions and gas pool dimensions were prepared (Table 1). In the table, the terms "predetermined region", "thin-walled region", and "exception region" defined in the section of other embodiments are used. In addition, the conditions (materials, dimensions, etc.) that are not specified are those in accordance with the first embodiment described above. In particular, d ₂ / d ₀ was set to 0.8 or more in the entire second region. Further, in all the examples, the lengths of the porous portion and the gas pool were the same.

(Comparison example)
A nozzle for continuous casting was prepared in the same manner as in Example 4 except that the porous portion and the cross-sectional shape of the gas pool were perfectly circular, and used as a comparative example.

〔Evaluation method〕
For each continuous casting nozzle prepared as described above, a continuous casting nozzle was installed at a portion where molten steel was flown from the tundish to the mold, and the state of adhesion of alumina after casting the aluminum killed steel was visually observed. The observed adhesion of alumina was evaluated in the following four stages.
A: No adhesion of alumina was observed.
B: A slight adhesion of alumina was observed.
C: A large amount of alumina was observed.
D: A very large amount of alumina was observed.

〔result〕
As shown in Table 1, in the comparative example in which the cross-sectional shape of the porous portion and the gas pool is a perfect circle regardless of any of the embodiments shown in FIGS. 4, 7, 8 and 9. Compared with this, the degree of adhesion of alumina was improved. Further, in Example 2 in which the exception region was provided in the predetermined region, the improvement in the degree of alumina adhesion comparable to that in the other comparative examples in which the exception region was not provided was observed.

The present invention can be used, for example, as a nozzle for continuous casting for pouring molten steel discharged from a tundish into a mold.

100: Nozzle for continuous casting 200: Nozzle for continuous casting 11: Upper nozzle 11a: First flow path 12: Fixed plate 12a: Second flow path 13: Lower nozzle 13a: Third flow path 13b: Discharge hole 14 : Seal board 14a: Fourth flow path part 20: Sliding board 21: Plate-shaped part 22: Opening 30: Gas supply mechanism 31: Porous part 32: Gas pool 111: First region (upper nozzle 11)
111a: Predetermined area (upper nozzle 11)
112: Second region (upper nozzle 11)
201: First region (sliding board 20)
201a: Predetermined area (sliding board 20)
202: Second region (sliding board 20)
20A: Communication posture 20B: Closed posture

Claims (6)

A refractory for continuous casting that can distribute molten steel,
It is provided with an upper nozzle having a first flow path portion, a fixing plate having a second flow path portion, a lower nozzle having a third flow path portion, and a sliding plate having an opening and a plate-like portion.
The fixing plate is provided so that the first flow path portion and the second flow path portion communicate with each other at the downstream end portion of the first flow path portion.
The sliding plate and the lower nozzle are provided so as to be slidable integrally with the fixed plate, wherein the sliding plate and the lower nozzle are the second flow path portion and the third. It is slidable over a communication posture in which the flow path portion and the opening allow fluid communication, and a closed posture in which the plate-shaped portion closes the downstream end of the second flow path portion.
At least one of the first flow path portion, the second flow path portion, the third flow path portion, and the opening includes the flow path portion or a porous portion facing the entire circumference of the opening. However, the side of the porous portion that does not face the flow path or the opening faces the gas pool that communicates with the gas supply source.
The first flow path portion, the second flow path portion, the third flow path portion, and the opening are divided into a first region and a second region, respectively.
With respect to the first flow path portion and the second flow path portion, the sliding when the posture is changed from the closed posture to the communication posture with the center of the flow path portion in the cross section orthogonal to the flow direction of the molten steel as the origin. In a polar coordinate system in which the direction of motion is a declination of 0 °, a region having a declination of 0 ° ± 120 ° is the first region, and a region having a declination of 180 ° ± 60 ° is the second region.
With respect to the opening and the third flow path, the sliding direction when the posture is changed from the communication posture to the closed posture with the center of the opening in the cross section orthogonal to the flow direction of the molten steel as the origin. In the polar coordinate system in which the declination is 0 °, the region having the declination of 0 ° ± 120 ° is the first region, and the region having the declination of 180 ° ± 60 ° is the second region.
In at least one of the first flow path portion, the second flow path portion, the third flow path portion, and the opening portion provided with the porous portion, the flow direction of the molten steel of the porous portion. The maximum thickness in the direction orthogonal to is d ₀ ,
In 80% or more of the predetermined region including the region having the declination angle of 0 ° ± 15 ° in _{the first region, d 0 and the thickness d 1 of the} porous portion facing the first region. The ratio d ₁ / d ₀ is 0.2 or more and 0.8 or less.
In the entire region of the second region, and d _0, the ratio d _{2 /} d ₀ of the thickness d ₂ of the porous portion facing the second region, is greater than 0.8 continuous casting refractories. A refractory for continuous casting that can distribute molten steel,
An upper nozzle having a first flow path, a fixing plate having a second flow path, a lower nozzle having a third flow path, a seal board having a fourth flow path, and a slide having an opening and a plate-like portion. With a motive,
The fixing plate is provided so that the first flow path portion and the second flow path portion communicate with each other at the downstream end portion of the first flow path portion.
The seal board is provided so that the third flow path portion and the fourth flow path portion communicate with each other at the upstream end portion of the third flow path portion.
The sliding board has a communication posture in which the second flow path portion, the fourth flow path portion, and the opening are in communication with each other, and the sliding board is formed between the second flow path portion and the fourth flow path portion. It is slidable with respect to the fixing plate and the sealing plate over the closed posture in which the plate-shaped portion is inserted.
At least one of the first flow path portion, the second flow path portion, the third flow path portion, the fourth flow path portion, and the opening portion is located on the entire circumference of the flow path portion or the opening portion. A facing porous portion is provided, and the side of the porous portion that does not face the flow path or the opening faces the gas pool that communicates with the gas supply source and the fluid.
The first flow path portion, the second flow path portion, the third flow path portion, the fourth flow path portion, and the opening are divided into a first region and a second region, respectively.
The origin of the first flow path portion, the second flow path portion, the third flow path portion, and the fourth flow path portion is the center of the flow path portion in the cross section orthogonal to the flow direction of the molten steel. In a polar coordinate system in which the sliding direction when the posture is changed from the closed posture to the communication posture is a deviation angle of 0 °, a region having a deviation angle of 0 ° ± 120 ° is the first region, and the deviation angle is The region of 180 ° ± 60 ° is the second region.
With respect to the opening, the center of the opening in the cross section orthogonal to the flow direction of the molten steel is set as the origin, and the sliding direction when changing the posture from the communicating posture to the closed posture is set to an argument of 0 °. In the polar coordinate system, the region having a declination of 0 ° ± 120 ° is the first region, and the region having a declination of 180 ° ± 60 ° is the second region.
The porous portion is provided in at least one of the first flow path portion, the second flow path portion, the third flow path portion, the fourth flow path portion, and the opening portion, which comprises the porous portion. The maximum thickness of the molten steel in the direction orthogonal to the flow direction is d ₀ .
In 80% or more of the predetermined region including the region having the declination angle of 0 ° ± 15 ° in _{the first region, d 0 and the thickness d 1 of the} porous portion facing the first region. The ratio d ₁ / d ₀ is 0.2 or more and 0.8 or less.
In the entire region of the second region, and d _0, the ratio d _{2 /} d ₀ of the thickness d ₂ of the porous portion facing the second region, is greater than 0.8 continuous casting refractories. The refractory for continuous casting according to claim 1 or 2, wherein the 50% pore diameter of the porous portion by the mercury press-fitting method is 5 μm or more and 200 μm or less. The refractory for continuous casting according to any one of claims 1 to 3, wherein the length of the porous portion along the flow direction of the molten steel is 5 mm or more. The thickness of the gas pool in the direction away from the flow path portion is 0.5 mm or more.
The refractory for continuous casting according to any one of claims 1 to 4, wherein the length of the gas pool along the flow direction of the molten steel is 5 mm or more. The distance between the sliding board in the direction along the flow direction of the molten steel from the intermediate portion of the length along the flow direction of the molten steel is the maximum in the direction orthogonal to the flow direction of the molten steel in the opening. The fireproof material for continuous casting according to any one of claims 1 to 5, wherein at least a part of the gas pool is provided in a region that is significantly three times or less.

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