JP7256391B2 - Pouring equipment for molten metal - Google Patents

Description

The present invention relates to a molten metal pouring device, and more particularly to a molten metal pouring device for pouring molten metal through a sliding gate provided at the bottom of a ladle.

In the continuous casting of molten metal, such as molten steel, molten steel contained in a ladle is poured into a tundish and poured from the tundish into a mold. A flow control mechanism such as a sliding gate is provided at the bottom of the ladle, and molten steel is poured into the tundish on the downstream side of the sliding gate. For the molten steel flow from the sliding gate at the bottom of the ladle to the surface of the molten steel in the tundish, in order to prevent the molten steel from oxidizing due to contact with the air, means are taken to isolate the molten steel flow from the atmosphere. There is usually a refractory tube surrounding the molten steel stream, called an injection tube (for continuous casting) or a long nozzle. Injection pipes and long nozzles are collectively called "surrounding pipes" here.

When casting a molten metal such as molten steel into an ingot, the molten steel contained in the ladle flows downward through a sliding gate at the bottom of the ladle and is cast into a mold (ingot case). In top pour casting, a mold is placed below a ladle, and molten steel is poured into the mold from the ladle. In the case of bottom pouring casting, a pouring pipe (for ingot casting) is placed below the ladle, and molten steel is poured from the ladle through a sliding gate into the pouring pipe. Molten steel is poured into the mold.

In the continuous casting of molten steel, since the slab is cast at a predetermined constant casting speed, the molten steel pouring speed from the tundish into the mold is kept constant. Since the amount of molten steel in the tundish is also kept constant, it is necessary to keep the molten steel pouring rate (tons/minute) from the ladle to the tundish constant as well. The molten steel pouring speed from the ladle is controlled by adjusting the opening of the sliding gate at the bottom of the ladle.

The injection speed (ton/min) of molten steel (molten metal) passing through the sliding gate is proportional to the product of the flow speed (m/min) of molten steel passing through the sliding gate opening and the opening area of the sliding gate. Since the molten steel flow velocity is proportional to the square root of the molten steel head at the sliding gate (altitude difference between the molten steel surface in the ladle and the lower end of the lower nozzle), when the molten steel head becomes smaller at the end of the ladle pouring, Since the flow velocity (m/min) of molten steel passing through the sliding gate opening decreases, it is necessary to widen the opening of the sliding gate to secure the required molten steel injection velocity (ton/min). Therefore, the channel hole cross-sectional area of the plate that constitutes the sliding gate (corresponding to the opening area of the sliding gate when the opening degree is 100%) is sufficient even when the molten steel head is the lowest at the end of the pouring of the ladle. The required flow hole cross-sectional area is adopted to ensure the molten steel injection rate (tons/minute). Since the molten steel head is large from the early stage to the middle stage of pouring into the ladle, it is necessary to keep the molten steel pouring speed constant, so pouring is performed by narrowing the opening of the sliding gate. Sliding gates are known to cause molten steel flow diffusion during throttle injection.

Patent Document 1 discloses an example of using a pouring pipe as a surrounding pipe surrounding molten steel pouring flow from a ladle to a tundish in continuous casting. According to Patent Document 1, the splash mainly generated when the pouring flow from the ladle collides with the molten steel in the tundish, and the base metal adheres and accumulates on the inner wall surface of the pouring pipe. It is described that casting becomes impossible.

JP-A-5-293614

When performing continuous casting of molten steel, a device having a structure shown in FIG. 13 was used as a device for pouring molten steel from a ladle to a tundish. A ladle 21 has a sliding gate 1 at the bottom, a lower nozzle 11 below the sliding gate 1, and a surrounding pipe 13 below the lower nozzle 11. The lower end of the surrounding pipe 13 is the molten metal 23 in the tundish. It is immersed in (molten steel). When the inner wall of the surrounding pipe was examined after continuous casting, metal adhesion was found on the inner wall. FIG. 13 shows the bare metal adhering portion 26 . From the position of the bare metal adhering portion 26, it was presumed that the main cause of the ingot adhesion was that the discharged flow from the sliding gate diffused and adhered to the bare metal adhering portion 26 inside the surrounding pipe.
Adhesion/accumulation of metal on the surrounding tube 13 (injection tube 14) causes clogging of the injection tube, which not only lowers the throughput of continuous casting, but also shortens the replacement cycle of the injection tube. It leads to cost increase.
SUMMARY OF THE INVENTION An object of the present invention is to prevent diffusion of a discharge flow from a sliding gate in a molten metal pouring apparatus for pouring molten metal through a sliding gate provided at the bottom of a ladle.

That is, the gist of the present invention is as follows.
[1] A pouring device for pouring molten metal contained in a ladle,
The bottom of the ladle has a sliding gate that adjusts the flow rate of the molten metal.
The sliding gate has a plurality of plates formed with passage holes through which the molten metal passes, at least one of the plates being a slidable slide plate,
The channel holes in each plate form upstream surface openings on the upstream surface of the plate surface located upstream of the molten metal passing therethrough, and form upstream surface openings on the downstream surface located downstream of the surface of the plate. Forming the apertures, the direction from the center of gravity of the upstream surface aperture pattern to the center of gravity of the downstream surface aperture pattern is defined as the channel axis direction,
The channel axis line inclination angle α formed by the channel axis direction and the downstream direction perpendicular to the sliding surface of the plate (hereinafter referred to as the “sliding surface perpendicular downstream direction”) is 5° or more and 75° or less,
The direction in which the channel axis direction is projected onto the sliding surface is called the sliding surface channel axis direction, and the direction in which the slide plate slides when the sliding gate is closed is called the sliding closing direction. The angle formed by the sliding surface flow path axis direction clockwise with respect to the closing direction when viewed in the sliding surface perpendicular downstream direction is called a flow path axis rotation angle θ (within a range of ±180 degrees). The axis line rotation angle θ differs between adjacent plates, and the θ of the plate on the most upstream side is θ ₁ , the θ of the plate one downstream of that is θ ₂ , and the θ of the plate one further downstream is θ Numbered in order from ₃ , and Δθ _N = θ _N - θ _N+1 (N is an integer of 1 or more and up to the number of plates - 1),
An apparatus for pouring molten metal, wherein all angles Δθ _N are 10° or more and less than 170°, or all angles Δθ _N are more than -170° and -10° or less.
[2] It is characterized by having a refractory surrounding pipe arranged below the sliding gate so as to surround the molten metal flowing down from the sliding gate, and an intermediate container for containing the molten metal flowing down from the ladle. The molten metal pouring device according to [1].
[3] The inner space of the surrounding pipe has a cylindrical or rectangular horizontal cross-sectional shape,
When the inner diameter of the passage hole of the sliding gate is D, the inner diameter of the surrounding pipe is 3 × D or more, and the molten metal flowing down from the ladle is blocked from the atmosphere [2] 2. The molten metal pouring device according to .
[4] The molten metal according to any one of [1] to [3], wherein the number of plates forming the sliding gate is two or three and the number of slide plates is one. pouring device.

In a molten metal pouring apparatus for pouring molten metal through a sliding gate provided at the bottom of a ladle, the present invention can prevent the discharge flow from the sliding gate from diffusing.
By using the present invention as a molten metal pouring device for pouring molten metal into a tundish, a swirling flow is formed in the flow of molten metal flowing down in the surrounding pipe (injection pipe), and then a falling flow is generated. It does not spread in the horizontal direction, does not fluctuate unstable, and flows down without contacting the injection pipe. This prevents metal from adhering and accumulating on the injection pipe, clogging the injection pipe and reducing throughput. and does not shorten the life of the injection tube.

1 is a conceptual cross-sectional view showing a molten metal pouring apparatus according to the present invention; FIG. FIG. 2 is a diagram showing a sliding gate of the molten metal pouring apparatus of the present invention, where (A) is an upper fixed plate, (B) is a slide plate, (C) is a plan view of the lower fixed plate, and (D) is a sliding gate. A front view of a combination of a gate and a lower nozzle, (E) is a view taken along line EE, and (F) is a sectional view taken along line FF. 1 is a view showing a sliding gate of a molten metal pouring apparatus of the present invention, (A) is a view from the AA arrow, (B) is a view from the BB arrow, and (C) is a view from the CC arrow. , (D) is a front view of a combination of a sliding gate and a lower nozzle, and (E) is a view taken along line EE. It is a diagram showing the flow in the sliding gate of the present invention, (A) is an AA arrow view, (B) is a BB arrow view, (C) is a CC arrow view, (D) is a front view of a combination of a sliding gate and a lower nozzle, and (E) is a view taken along line EE. FIG. 2 is a view showing a sliding gate of the molten metal pouring device of the present invention, (A) is an upper fixed plate, (B) is a slide plate, (C) is a front view of a combination of the sliding gate and the lower nozzle, (D ) is a view taken along the line DD, and (E) is a cross-sectional view taken along the line EE. FIG. 2 is a view showing the sliding gate of the molten metal pouring device of the present invention, (A) is a view from the AA arrow, (B) is a view from the BB arrow, and (C) is the sliding gate and the lower nozzle. Combined front view, (D) is a DD arrow view. 1 is a diagram showing an example of an upper fixing plate of the present invention, where (A) is a plan view, (B) is a front view, (C) is a side view, and (D) is a cross-sectional view taken along line DD. FIG. 10 is a view showing a sliding gate of a comparative example, (A) is an upper fixed plate, (B) is a slide plate, (C) is a front view of a combination of the sliding gate and the lower nozzle, and (D) is a DD arrow view. FIG. (E) is a cross-sectional view taken along line EE. FIG. 10 is a view showing a sliding gate of a comparative example, (A) is a view on the AA arrow, (B) is a view on the BB arrow, (C) is a front view of a combination of the sliding gate and the lower nozzle, (D ) is a DD arrow view. FIG. 3 is a diagram showing a conventional sliding gate, (A) is an upper fixed plate, (B) is a slide plate, (C) is a plan view of a lower fixed plate, and (D) is a front view of a combination of a sliding gate and a lower nozzle. (E) is a view taken along line EE, and (F) is a sectional view taken along line FF. FIG. 2 is a diagram showing a conventional sliding gate, (A) is an AA arrow view, (B) is a BB arrow view, (C) is a CC arrow view, and (D) is a sliding gate. A front view of a combination of lower nozzles, and (E) is a view taken along line EE. It is a figure which shows the streamline of the discharge flow from a lower nozzle front-end|tip, (A) is the example of this invention which formed the swirl flow, (B) is the comparative example which does not form a swirl flow. FIG. 2 is a conceptual cross-sectional view showing a molten metal pouring device of a comparative example. FIG. 5 is a diagram showing the relationship between the opening degree of a sliding gate and the spread angle of a discharge flow for an example of the present invention in which a swirl flow is formed and a comparative example in which a swirl flow is not formed; FIG. 6 is a diagram showing a comparison of the amount of base metal adhered to the inner wall of a surrounding pipe between an example of the present invention in which a swirl flow is formed and a comparative example in which no swirl flow is formed.

The present invention relates to a molten metal pouring device, and more particularly to a molten metal pouring device for pouring molten metal through a sliding gate provided at the bottom of a ladle. As molten metal, preferably molten steel is used. A case where the molten metal is molten steel will be described below as an example.

As shown in FIGS. 10 and 11, the sliding gate 1 arranged at the bottom of the ladle 21 is configured by stacking two or three plates 2, and each plate 2 has a channel hole. 6 is provided. Slide the slide plate 4 of the plates constituting the sliding gate 1, and when the sliding gate 1 is "open" due to the overlapping of the flow passage holes 6 of each plate, the flow from the upstream side to the downstream side of the flow passage hole 6 Molten metal flows toward the side. A direction perpendicular to the sliding surface 30 of the plate 2 and directed to the downstream direction (sliding surface vertical downstream direction 32) is directed vertically downward from top to bottom. 10 and 11, in a conventionally used sliding gate, the channel hole 6 of the plate 2 normally has a cylindrical inner peripheral shape, and the axial direction of the cylinder is perpendicular to the sliding surface. It is configured parallel to the direction 32 . A lower nozzle 11 is arranged below the sliding gate 1 .

In the continuous casting of steel, as shown in FIG. 13, a tundish 25 is arranged as an intermediate container 22 below a ladle 21, and molten steel flows into the tundish 25 via a sliding gate 1 provided at the bottom of the ladle. , and then injected from the tundish into a mold (not shown). A sliding gate 1 provided at the bottom of the ladle functions as a flow control mechanism. Regarding the molten steel flow from the sliding gate 1 at the bottom of the ladle to the molten steel surface (molten metal surface 24) in the tundish 25, in order to prevent the molten steel from oxidizing due to contact with the atmosphere, as a means of isolating the molten steel flow from the atmospheric atmosphere, A surrounding pipe 13 (injection pipe 14 or long nozzle) is arranged to surround the molten steel flow.

As mentioned above, the cross-sectional area of the channel holes 6 in each plate 2 that constitutes the sliding gate 1 at the bottom of the ladle is as large as necessary to ensure a sufficient molten steel pouring rate even when the molten steel head in the ladle is at its lowest. A flow hole cross-sectional area is adopted. Since the molten steel head is large from the early stage to the middle stage of pouring into the ladle, it is necessary to keep the molten steel pouring speed (per unit time flow rate) constant. It is known that the sliding gate 1 causes diffusion of the molten steel flow during throttle injection. In the continuous casting of molten steel, as described above, the reason why the ingot adhered to the ingot-attached portion 26 on the inner wall of the surrounding pipe 13 is that the sliding gate 1 is being squeezed while the opening of the sliding gate 1 is narrowed. It was conceived that the discharge flow from 1 diffused and adhered as a result. Further, it was conceived that the diffusion of the discharged flow could be reduced by imparting a swirling motion to the downstream flow flowing down from the sliding gate 1 to the lower nozzle inner hole 12 below.

Here, a conventional sliding gate and a sliding gate of the present invention capable of imparting a swirling motion to the discharge flow will be described with reference to FIGS. 1 to 11. FIG.

10 and 11, in a conventionally used sliding gate, the channel hole 6 of the plate 2 normally has a cylindrical inner peripheral shape, and the axial direction of the cylinder is perpendicular to the sliding surface. It is configured parallel to the direction 32 . On the other hand, in the present invention, as shown in Figs. By appropriately combining two or three plates with oblique holes in different directions, the molten metal flow inside the sliding gate 1 and the lower nozzle 11 on the downstream side thereof can be controlled only toward the downstream side. Instead, the circumferential flow velocity is added to form a swirling flow.

As the cross-sectional shape of the channel hole 6, a cylindrical shape having a perfectly circular cross section perpendicular to the axial direction is normally used. In the sliding gate 1 of the present invention, the channel hole 6 formed in the plate 2 is not limited to a cylindrical shape, and the axial direction of the channel hole may also change within the plate. do not have. Therefore, first, the axis of the channel hole 6 formed in the plate 2 is defined.

The passage hole 6 of the conventional sliding gate 1 will be described with reference to FIG. A sliding gate 1 of FIG. 10 has three plates 2, and consists of an upper fixed plate 3, a slide plate 4, and a lower fixed plate 5 from the upstream side. Each plate 2 has a cylindrical shape with a perfectly circular cross section, and is formed with a channel hole 6 whose axial direction is oriented in the direction perpendicular to the sliding surface 30 (vertical downstream direction 32 of the sliding surface). there is The upstream surface of each plate is called an upstream surface 7u, and the downstream surface thereof is called a downstream surface 7d. A figure (upstream side surface aperture) formed by the inner peripheral surface of the channel hole 6 on the upstream surface 7u is called an upstream aperture 8u. A figure (downstream side surface aperture) formed by the inner peripheral surface of the channel hole 6 on the downstream surface 7d is referred to as a downstream aperture 8d. In the example shown in FIG. 10, the axis of the cylindrical shape of the channel hole 6 is perpendicular to the sliding surface, so in FIGS. 10(A) to (C), the upstream opening 8u and the downstream opening 8d overlap. . If the shapes of the upstream opening 8u and the downstream opening 8d are regarded as figures, respectively, the center of gravity of the figures can be defined. The center of gravity of the upstream surface aperture figure is called the upstream center of aperture 9u, and the center of gravity of the downstream surface aperture figure is called the lower center of gravity 9d. In the example shown in FIG. 10, both the upstream apertures 8u and the downstream apertures 8d are circular in shape, so the centroids 9u and 9d of the upstream apertures coincide with the centers of the perfect circles. Next, a flow path axial direction 10 is defined as a direction that passes through the upstream hole center of gravity 9u and the downstream hole center of gravity 9d and faces the downstream side. In the example shown in FIG. 10 , the channel axis direction 10 is the same as the sliding surface perpendicular downstream direction 32 . In FIG. 10(F), the line depicted by the dashed dotted line is the channel axial direction 10 .

Next, referring to FIG. 2, the passage hole 6 of the sliding gate 1 of the present invention will be explained. The sliding gate 1 of FIG. 2 has three plates, and consists of an upper fixed plate 3, a slide plate 4, and a lower fixed plate 5 from the upstream side. Each plate is formed with a channel hole 6 whose axial cross section is a perfect circle and whose axial direction is tilted from the downstream direction 32 perpendicular to the sliding surface. The upper fixing plate 3 will be described as an example with reference to FIGS. 2(A) and 2(F). FIG. 2(F) is a cross-sectional view taken along line FF of FIG. 2(A). Since the axial direction of the cylinder and the sliding surface perpendicular downstream direction 32 are inclined, the upstream opening 8u and the downstream opening 8d are drawn at different positions in FIG. 2(A). Since the cross section in the axial direction is a perfect circle and the axial direction is a cylinder inclined from the downstream direction 32 perpendicular to the sliding surface, the upstream opening 8u and the downstream opening 8d each form an ellipse slightly deviating from a perfect circle. ing. However, it is drawn as a perfect circle on the drawing for convenience. The centroids of the respective figures of the upstream apertures 8u and the downstream apertures 8d can be defined as the upstream aperture centroid 9u and the downstream aperture centroid 9d. Furthermore, the channel axis direction 10 can be determined so as to pass through the upstream hole center of gravity 9u and the downstream hole center of gravity 9d and face the downstream side. In FIG. 2(F), the line depicted by the dashed dotted line is the channel axial direction 10 . In the example shown in FIG. 2 , the channel axial direction 10 coincides with the axial direction of the cylindrical shape that forms the channel hole 6 and has a perfectly circular cross section in the axial direction. Here, the angle between the downstream direction perpendicular to the sliding surface of the plate (sliding surface perpendicular downstream direction 32) and the channel axis direction 10 is defined as channel axis inclination angle α. Here, the reason why the center of gravity of the opening is used instead of the center of the circle to determine the direction of the channel axis is to universally define the direction of the channel axis even when the shape of the aperture is not a perfect circle.

In the example shown in FIG. 10, the downstream opening 8d of the upper fixed plate 3 and the upstream opening 8u of the slide plate 4, and the downstream opening 8d of the slide plate 4 and the upstream opening 8u of the lower fixed plate 5 are aligned with each other. At the same time, the sliding position of the slide plate 4 is fixed, that is, the sliding gate 1 is fully open (see FIG. 10(D)). In the sliding gate 1 shown in FIG. 10, the opening degree of the sliding gate 1 can be reduced by moving the slide plate 4 leftward in the figure. FIG. 11 shows the same sliding gate 1 as in FIG. 10 with the degree of opening reduced to 1/2. By further moving the position of the slide plate 4 to the left in the figure, the sliding gate 1 can be fully closed. The same applies to the examples shown in FIGS. In FIG. 2, the sliding gate 1 is fully open, the downstream opening 8d of the upper fixed plate 3 and the upstream opening 8u of the slide plate 4, the downstream opening 8d of the slide plate 4 and the upstream opening 8u of the lower fixed plate 5 are The sliding position of the slide plate 4 is determined so as to match each other. FIG. 3 shows the same sliding gate 1 as in FIG. 2, with the opening degree of the sliding gate 1 being 1/2. Therefore, the direction in which the slide plate 4 slides when the sliding gate 1 is closed is hereinafter referred to as "sliding closing direction 33".

In the example of the present invention shown in FIG. 2, the channel axis direction 10 is inclined at the channel axis inclination angle α with respect to the sliding surface perpendicular downstream direction 32, so the channel axis direction 10 is projected onto the sliding surface. When the direction is defined as the sliding surface flow path axis direction 31, the sliding surface flow path axis direction 31 can be determined. In FIGS. 2A to 2C and 2F, the sliding surface flow path axial direction 31 is indicated by thin arrows. In addition, in FIGS. 2A to 2C, the sliding surface channel axial direction 31 overlaps the channel axial direction 10. As shown in FIG. In addition, in the example shown in FIG. 10, since the channel axis direction 10 faces the sliding surface perpendicular downstream direction 32, the sliding surface channel axis direction 31 does not appear in FIGS. .

Next, the angular relationship between the sliding surface channel axis direction 31 and the sliding closing direction 33 will be defined. The angle formed by the sliding surface channel axis direction 31 with respect to the sliding closing direction 33 clockwise when viewed in the sliding surface vertical downstream direction 32 is called a channel axis rotation angle θ. The channel axis rotation angle θ is defined as an angle in the range of ±180°. That is, when the sliding surface flow path axis direction 31 becomes an angle (θ') exceeding +180° clockwise when viewed in the sliding surface perpendicular downstream direction 32, "θ = θ' - 360°" Define the angle θ as a negative value. As a subscript of the angle θ, the θ of the most upstream plate is numbered as θ ₁ , the θ of the plate one downstream thereof is θ ₂ , and the θ of the plate one further downstream is θ ₃ . When θ _N is representatively expressed, N is an integer of 1 or more and means a numerical value up to the number of plates of the sliding gate 1 . In the example shown in FIG. 2, the upper fixed plate 3 has an angle θ ₁ =−45°, the slide plate 4 has an angle θ ₂ =+90°, and the lower fixed plate 5 has an angle θ ₃ =−1.
35°.

Furthermore, in the sliding gate 1, the relationship of the channel axis line rotation angle between two plates that are in contact with each other is defined as follows. That is, Δθ _N is determined as Δθ _N =θ _N -θ _N+1 . Δθ _N is defined as an angle in the range of ±180 degrees, like θ _N above. That is, when Δθ _N becomes an angle (Δθ _N ') exceeding +180°, Δθ _N is defined as a negative value by setting "Δθ _N =Δθ _N '-360°". Also, when Δθ _N becomes an angle (Δθ _N ') less than -180°, Δθ _N is defined as a positive value by setting "Δθ _N =Δθ _N '+360°". As a result, Δθ _N becomes a number within the range of ±180°. Here, when Δθ _N is more than 0° and less than +180°, it indicates that the channel axis line rotation angle θ _N changes counterclockwise from upstream to downstream. Conversely, when Δθ _N is more than −180° and less than 0°, it indicates that the channel axis rotation angle θ _N changes clockwise from upstream to downstream. In the example shown in FIG. 2, since Δθ ₁ =θ ₁ -θ ₂ =-135° and Δθ ₂ '=θ ₂ -θ ₃ =225°, Δθ ₂ =Δθ ₂ '-360°=-135° . Both Δθ ₁ and Δθ ₂ are within the range of -180° to 0°, indicating that the channel axis rotation angle changes clockwise.

Based on the above preparations, the conditions that the sliding gate 1 of the present invention should have and the reasons thereof will be described.

In the conventional sliding gate 1, as shown in FIGS. 10 and 11, the flow channel axis direction 10 is perpendicular to the sliding surface, that is, the flow channel axis inclination angle α is 0°, and there is an inclination. I didn't. In contrast, the first feature of the present invention is that the channel axis direction 10 is inclined with respect to the sliding surface perpendicular downstream direction 32, and the channel axis line inclination angle α is not 0°. Since the flow path axis is tilted with respect to the downstream direction 32 perpendicular to the sliding surface, the molten metal flowing in the plate not only has a velocity component in the downstream direction 32 perpendicular to the sliding surface, but also has a velocity component in the downstream direction 32 perpendicular to the sliding surface. It has a perpendicular velocity component (horizontal velocity component). In the present invention, the channel axis line inclination angle α is 5° or more and 75° or less. By setting the angle α to 5° or more, the molten metal has a sufficient horizontal velocity component, which makes it possible to form a swirling flow in the lower nozzle as described below. The angle α is preferably 15° or more, more preferably 25° or more. On the other hand, if the angle α is too large, it is not preferable from the viewpoint of ensuring the strength of the refractory and suppressing wear, so the angle α is set to 75° or less. The angle α is preferably 65° or less, more preferably 55° or less.

Regarding the state of the opening of the sliding gate 1 at the bottom of the ladle during continuous casting, in the steady state of casting at a constant casting speed, the opening of the sliding gate is limited except at the end of pouring when the molten steel head in the ladle is lowered. The cross-sectional area of the sliding gate passage hole is selected so that casting can be performed in a narrowed state (see FIG. 11) rather than fully open (see FIG. 10). In FIG. 11, the opening degree of the sliding gate 1 is 1/2. In this case, the opening area of the sliding gate 1 is calculated to be 0.31 times the cross-sectional area of the perfectly circular channel hole.

FIG. 3 shows a sliding gate in which the opening degree of the sliding gate 1 (fully opened) of the present invention having the shape shown in FIG. 2 is changed to 1/2. 3(A) is a view taken along the line AA in FIG. 3(D), in which the downstream opening 8d of the upper fixing plate 3 is partly drawn in solid lines and partly in dashed lines, and the slide plate 4 is drawn in the upstream direction. Only the aperture 8u (4) is similarly drawn with a partly solid line and a partly broken line. FIG. 3(B) is a view taken along line BB of FIG. 3(D), in which all the upstream openings 8u of the slide plate 4 are drawn with solid lines, and the downstream openings 8d are drawn with some solid lines and some broken lines. , the upstream opening 8u of the lower fixing plate 5 is also drawn with a solid line and a broken line, and the downstream opening 8d is drawn with a broken line. FIG. 3(C) is a CC arrow view of FIG. 3(D), in which all the upstream openings 8u of the lower fixing plate 5 are drawn with solid lines, and the downstream openings 8d are drawn with some solid lines and some broken lines. there is

The flow of molten metal in the passage hole of the sliding gate and in the lower nozzle when the opening is set to 1/2 as shown in FIG. 3 will be described based on FIG. In FIG. 4, FIG. 4A is a view taken along line AA in FIG. 4, only the upstream aperture 8u is similarly drawn with a partly solid line and a partly broken line. 4(B) is a view taken along line BB in FIG. 4(D), in which the position of the downstream opening 8d (3) of the upper fixing plate 3 is indicated by a chain double-dashed line, and the upstream opening of the slide plate 4 is shown. 8u is drawn in full line, the downstream opening 8d is drawn in part in solid line and part in broken line, the upstream opening 8u of the lower fixing plate 5 is likewise drawn in part in solid line and part in broken line, and the downstream opening 8d is drawn in whole in broken line. is depicted in FIG. 4(C) is a CC arrow view of FIG. 4(D), in which the position of the downstream opening 8d (4) of the slide plate 4 is indicated by a two-dot chain line, and the upstream opening of the lower fixing plate 5 is shown. 8u is drawn entirely in solid lines, and the downstream opening 8d is drawn in partly in solid lines and partly in broken lines. Further, stream lines 18 of the molten metal are indicated by thick line arrows in FIGS. 4A to 4C, and by thick broken line arrows in FIGS.

Regarding the sliding gate 1 of FIGS. 2 and 3, as described above, the difference Δθ _N between the adjacent channel axis rotation angles θ _N is Δθ ₁ =Δθ ₂ =−135 _° . Since it is more than -180° and less than 0°, it indicates that the channel axis rotation angle θ _N changes clockwise from upstream to downstream. The molten metal flowing through the channel holes 6 of the upper fixed plate 3 flows along the channel axis direction 10 of the upper fixed plate 3 as shown in FIG. 4(A). At the contact surface between the upper fixed plate 3 and the slide plate 4, the downstream opening 8d of the upper fixed plate 3 (two-dot chain line in FIG. 4B) and the upstream opening 8u of the slide plate 4 (solid line in FIG. 4B) ) flow downstream in the small cross-section of the overlapping portion (opening). In the passage hole 6 of the slide plate 4, the downstream opening 8d of the upper fixed plate 3 (two-dot chain line in FIG. 4B) and the upstream opening 8u of the slide plate 4 (solid line in FIG. 4B) The molten metal flow flowing out from the small cross-section of the overlapping portion (opening) of the slide plate 4 along the inner wall surface (cylindrical surface) of the flow channel hole 6 as shown by the streamline 18 in FIG. The downstream opening 8d of the slide plate 4 (two-dot chain line in FIG. 4(C)) and the upstream opening 8u of the lower fixed plate 5 (solid line in FIG. 4(C)) form a swirling flow. flow out into the channel hole 6 of the lower fixing plate 5 from a small cross-section of the overlapping portion (opening portion). Inside the channel hole 6 of the lower fixed plate 5, a swirling flow is formed along the inner wall surface (cylindrical surface) of the channel hole 6 of the lower fixed plate 5, as shown by the streamline 18 in FIG. 4(C). , flows out into the lower nozzle 11 on the downstream side as it is, and as shown in FIGS. move on.

The difference between the flow path axis rotation angles θ _N of adjacent plates to form a swirling flow in the flow path hole 6 of the sliding gate 1 and also in the lower nozzle on the downstream side of the sliding gate 1 A condition for a certain angle Δθ _N will be described. As mentioned above, Δθ _N is defined as an angle within ±180°. Here, if Δθ _N is more than −10° and less than +10°, the difference between the channel axis rotation angles θ _N and θ _N+1 is too small to form a swirling flow. On the other hand, when Δθ _N is +170° or more or −170° or less, the absolute value of Δθ _N is too large, which rather hinders the formation of swirling flow. If the sliding gate 1 has two plates, only Δθ ₁ is defined and it is sufficient that the Δθ ₁ satisfies the above conditions. In addition to Δθ ₁ , Δθ ₂ and even more Δθ _N are defined when the sliding gate 1 has three or more plates. All of the Δθ _N must be 10° or more and less than 170°, or all of the angles Δθ _N must be more than -170° and -10° or less. As a result, when the channel axis direction 10 of the first and second plates changes clockwise, the third and subsequent plates also change clockwise in the same way. When the channel axis direction 10 changes counterclockwise, the third and subsequent sheets also change counterclockwise, so that a swirling flow can be effectively formed within the sliding gate. A more preferable range of Δθ _N is 30° or more and less than 165°, or more than -165° and -30° or less.

The number of plates forming the sliding gate 1 is preferably two or three. The examples shown in FIGS. 2 to 4 are for the case where the number of plates is three, as described above. In FIGS. 5 and 6, the number of plates is two, and the first plate from the upstream side constitutes the upper fixed plate 3 and the second plate constitutes the slide plate 4 . 5 shows the case when the opening is fully open, and FIG. 6 shows the case when the opening is 1/2. α=51.95°, θ ₁ =−26.57°, θ ₂ =+26.57°, Δθ ₁ =−53.14°, and a clockwise swirling flow can be formed. The reason why it is preferable that the number of plates forming the sliding gate 1 is 2 or 3 is that at least 2 plates are required to develop the throttle mechanism of the sliding gate, and 4 or more plates are unnecessary for flow rate adjustment. This is because the cost increases as the number of plates increases.

The channel hole 6 formed in the plate can also be a channel hole 6 having a shape as shown in FIG. FIG. 7 shows an example of the upper fixing plate 3. As shown in FIG. From the upstream surface 7u of the plate to the middle of the thickness, the shape of the flow passage hole 6 is a cylindrical shape with a perfectly circular cross section, and the axis of the cylinder is oriented in the downstream direction 32 perpendicular to the sliding surface. From the downstream surface 7d of the plate to the middle of the thickness, the channel hole 6 has a cylindrical shape with a perfectly circular cross section, and the axis of the cylinder is inclined from the downstream direction 32 perpendicular to the sliding surface. In the middle of the thickness of the plate, the channel hole 6 from the upstream surface 7u and the channel hole 6 from the downstream surface 7d are connected without a step. Even in a plate having channel holes 6 of such a shape, as shown in FIG. The direction facing the downstream aperture centroid 9d) can be defined as the channel axis direction 10. FIG.

The thickness of the plates constituting the sliding gate 1 may be the same, but the thickness of each plate may be different such that the slide plate 4 is the thinnest. In addition, the shape of the channel holes at the inlet and outlet of each plate of the sliding gate may be circles of the same size, but even if they are oval or elliptical, swirling flow can be obtained as long as the provisions of the present invention are met. is possible. Alternatively, the opening area may be different at the inlet and outlet of each plate.

The angle α may be the same or different for all plates.

《Water model experiment》
A water model experiment was performed to simulate the behavior of the molten metal flow flowing out from the sliding gate 1 at the bottom of the ladle. A 1/1 water model experimental machine was prepared for the ladle 21 and the sliding gate 1 at the bottom of the ladle 21 used in the test continuous casting apparatus for molten steel. As the sliding gate 1, the sliding gate of the present invention (hereinafter referred to as the "inventive gate") that imparts a turning motion and the conventionally used sliding gate (hereinafter referred to as the "normal gate") were used. The gate of the present invention has a shape having a _sliding gate 1 having three plates 2 and a lower nozzle ₁₁ below it, as shown in FIGS _. = 32°, θ ₁ = 36.101°, θ ₂ = 90°, θ ₃ = -143.899° (36.101-180). A clockwise swirling flow is formed. A normal gate has the shape shown in FIGS. 10 and 11, where α ₁ =α ₂ =α ₃ =0° and θ ₁ , θ ₂ , θ ₃ have no values. The diameter of the channel hole of the plate 2 is 40 mmφ, and the thickness of the plate 2 is 30 mm. Regarding the opening degree of the sliding gate 1, an opening degree of 0 mm is fully closed, and an opening degree of 40 mm is fully open.
The height difference (head) between the water surface in the ladle 21 and the lower end of the lower nozzle was kept constant at 1.5 m. Regarding the opening degree of the sliding gate 1, assuming the opening degree of the sliding gate of the ladle during continuous casting (the flow rate is adjusted by narrowing the opening degree except for the end of pouring into the ladle), 15 mm and 25 mm The behavior of the discharge flow flowing down from the lower end of the lower nozzle 11 was evaluated.

FIG. 12B schematically shows the behavior of the discharge flow of the normal gate. The discharge flow diffused irregularly, and at one moment it flowed down like a discharge flow 19 in the figure, and at another moment it flowed down like a discharge flow 19'. Looking at the spread angle φ of the discharge flow over the entire time, the smaller the degree of opening of the sliding gate, the larger the spread angle φ of the discharge flow.
FIG. 12(A) schematically shows the behavior of the discharge flow of the gate of the present invention. The discharge flow 19 does not fluctuate irregularly with time, and spreads at a relatively small discharge flow divergence angle φ. The results shown were obtained.

As is clear from FIG. 14, in the opening range used in the sliding gate 1 of the ladle 21 during continuous casting, the discharge flow spread angle φ of the gate of the present invention is smaller than that of the normal gate. found.
As for the shape of the lower nozzle 11 arranged below the sliding gate 1, a normal lower nozzle shape arranged below the sliding nozzle provided at the bottom of the ladle may be adopted.

《Molten metal pouring equipment used in continuous casting》
In continuous casting, as a pouring device for pouring molten metal contained in a ladle, as shown in FIGS. 1 and 13, below the sliding gate 1 provided at the bottom of the ladle 21, It has an intermediate vessel 22 for containing the molten metal flowing down from the ladle 21 and a refractory surrounding tube 13 arranged to surround the molten metal flowing down from the sliding gate 1 . Specifically, an injection pipe 14 or a long nozzle (not shown) is used as the surrounding pipe 13 . The intermediate container 22 is called tundish 25 . 1 and 13 illustrate the tundish wall top 27. FIG.

When a conventional sliding gate (ordinary gate) having the shape shown in FIGS. 10 and 11 was used, as shown in FIG. . The reason for this is thought to be that when a normal gate is used as the sliding gate 1 and throttle injection is performed, the discharge flow divergence angle φ becomes large. On the other hand, when the sliding gate of the present invention (the gate of the present invention) as shown in FIGS. 2 to 4 is used and arranged as shown in FIG. It was found that the amount of bare metal adhering to the inner circumference of the surrounding pipe was greatly reduced compared to when the gate was normally used.

In the molten metal pouring apparatus of the present invention provided with the surrounding pipe 13, the internal space of the surrounding pipe 13 has a cylindrical or rectangular horizontal cross-sectional shape. It is preferable that the inner diameter of the surrounding tube 13 is 3×D or more and that the flow of molten metal flowing down from the ladle is shielded from the atmosphere.

When the injection pipe 14 is used as the surrounding pipe 13, as shown in FIG. The immersion in the ladle 21 shields the stream of molten metal flowing down from the ladle 21 from the atmosphere. The surrounding pipe 13 has a two-stage structure of a lower injection pipe and an upper seal pipe, the upper end of the injection pipe is placed on the tundish lid, and the seal pipe sufficiently seals between the tundish lid and the ladle bottom. It is good also as a structure to carry out. If the space inside the tundish is sufficiently isolated from the atmosphere by the tundish and the tundish lid, even if the lower end of the injection pipe is not immersed in the molten steel in the tundish, the molten metal will flow down from the ladle. The flow is cut off from the atmosphere.

When a long nozzle is used as the surrounding pipe, the space between the upper end and the lower nozzle of the long nozzle is sufficiently sealed, and the lower end of the long nozzle is immersed in the molten steel in the tundish, so that the molten metal flows down from the ladle. is blocked from the atmosphere.

If the internal space of the surrounding pipe has a cylindrical or rectangular horizontal cross-sectional shape, the surrounding pipe can be easily formed.

As described above, when the inner diameter of the channel hole 6 of the plate 2 of the sliding gate 1 is D, the inner diameter of the surrounding tube 13 is preferably 3×D or more. If the inner diameter is smaller than this, even if the sliding gate of the present invention is used, the falling flow will come into contact with the inner periphery of the surrounding pipe and the base metal will adhere.

The angle from the inlet side to the outlet side of the inner circumference of the surrounding pipe is not vertical, but the diameter of the inner circumference increases from the inlet side to the outlet side, and the angle difference from the vertical is 1° or more. is desirable. As a result, the metal adhering to the inner circumference of the surrounding pipe is naturally cooled during continuous casting and when it solidifies and shrinks, it peels off, resulting in the effect of preventing metal adhesion. can be further improved. The inner diameter and draft angle of the surrounding pipe may be determined within a common-sense range, and a general shape may be used.

The present invention was applied in a test continuous casting apparatus. The tundish capacity is 0.7 tons. As a device for pouring molten metal, a sliding gate 1 is provided at the bottom of a ladle 21 for adjusting the flow rate of molten metal. A lower nozzle 11 is arranged below the sliding gate 1 . As shown in FIG. 1 (example of the present invention) and FIG. 13 (comparative example), an injection tube 14 is used as the surrounding tube 13 . A surrounding pipe lid 15 is provided at the upper end of the surrounding pipe 13 to sufficiently seal the opening of the surrounding pipe lid 15 and the lower nozzle 11 . The lower end of the enclosing tube 13 is below the molten metal surface 24 in the tundish and the enclosing tube 13 is submerged in the molten metal 23 . The sliding gate 1 has three plates 2 formed with passage holes 6 through which the molten metal passes, and the center plate is a slide plate 4 that can slide.

As the sliding gate 1, the sliding gate 1 of the present invention (hereinafter referred to as the "gate of the present invention") that forms a swirling flow within the lower nozzle 11, and the conventional sliding gate 1 (hereinafter referred to as the "normal gate") ) and prepared. In both the gate of the present invention and the normal gate, the passage hole diameter of the plate 2 is φ40 mm, and the plate thickness is 30 mm.
Regarding the channel axis line inclination angle α between the channel axis direction 10 and the downstream direction perpendicular to the sliding surface 30 of the plate 2 (sliding surface perpendicular downstream direction 32), the α of the upper fixed plate 3 is changed to α ₁ , α of the plate 4 is numbered α ₂ , α of the lower fixing plate 5 is numbered α ₃ , and so on. Similarly, the upper fixed plate 3, the slide plate 4, and the lower fixed plate 5 are also used for the flow channel axis rotation angle θ, which is the angle formed by the sliding surface flow channel axis direction 31 in the clockwise direction when viewed in the vertical downstream direction 32 of the sliding surface. Each θ is numbered sequentially as θ ₁ , θ ₂ , θ ₃ .

_{The gate of} the present _invention has the shapes shown in FIGS _. θ ₃ =−143.899° (36.101−180), forming a clockwise swirling flow in the flow of molten steel flowing down the inner hole of the lower nozzle 11 . A normal gate has the shape shown in FIGS. 10 and 11, where α ₁ =α ₂ =α ₃ =0° and θ ₁ , θ ₂ , θ ₃ have no values.

In order to evaluate the amount of bare metal adhered to the casting tube 14 during continuous casting, a "bare metal adhered amount" index was introduced. Continuous casting was performed by the test continuous casting machine, and the weight of the base metal adhering to the injection pipe 14 after continuous casting was measured. The molten steel flow rate per unit time is approximately 70 L/min on average, and the casting time is approximately 2 minutes (amount of molten steel is 980 kg). FIG. 15 shows the amount of base metal adhered for each sliding gate used as a pouring device for continuous casting. As is clear from FIG. 15, the effect of reducing the base metal adhesion amount when using the gate of the present invention is clear as compared with when using the normal gate.

1 sliding gate 2 plate 3 upper fixed plate 4 slide plate 5 lower fixed plate 6 channel hole 7u upstream surface (upstream side surface)
7d downstream surface (downstream surface)
8u upstream aperture (upstream surface aperture)
8d downstream aperture (downstream surface aperture)
9u: Center of gravity of upstream aperture (center of gravity of upstream surface aperture pattern)
9d Downstream aperture center of gravity (downstream surface trench drawing center of gravity)
10 Flow path axis direction 11 Lower nozzle 12 Lower nozzle inner hole 13 Surrounding pipe 14 Injection pipe 15 Surrounding pipe lid 18 Stream line 19 Discharge flow 21 Ladle 22 Intermediate container 23 Molten metal 24 Molten metal surface 25 Tundish 26 Base metal adhering part 27 Tundish wall upper end 30 Sliding surface 31 Sliding surface channel axis direction 32 Sliding surface vertical downstream direction 33 Sliding closing direction α Channel axis inclination angle θ Channel axis rotation angle

Claims (4)

A pouring device for pouring molten metal contained in a ladle,
The bottom of the ladle has a sliding gate that adjusts the flow rate of the molten metal.
The sliding gate has a plurality of plates formed with passage holes through which the molten metal passes, at least one of the plates being a slidable slide plate,
The channel holes in each plate form upstream surface openings on the upstream surface of the plate surface located upstream of the molten metal passing therethrough, and form upstream surface openings on the downstream surface located downstream of the surface of the plate. Forming the apertures, the direction from the center of gravity of the upstream surface aperture pattern to the center of gravity of the downstream surface aperture pattern is defined as the channel axis direction,
The channel axis line inclination angle α formed by the channel axis direction and the downstream direction perpendicular to the sliding surface of the plate (hereinafter referred to as the “sliding surface perpendicular downstream direction”) is 5° or more and 75° or less,
The direction in which the channel axis direction is projected onto the sliding surface is called the sliding surface channel axis direction, and the direction in which the slide plate slides when the sliding gate is closed is called the sliding closing direction. The angle formed by the sliding surface flow path axis direction clockwise with respect to the closing direction when viewed in the sliding surface perpendicular downstream direction is called a flow path axis rotation angle θ (within a range of ±180 degrees). The axis line rotation angle θ differs between adjacent plates, and the θ of the plate on the most upstream side is θ ₁ , the θ of the plate one downstream of that is θ ₂ , and the θ of the plate one further downstream is θ Numbered in order from ₃ , and Δθ _N = θ _N - θ _N+1 (N is an integer of 1 or more and up to the number of plates - 1),
An apparatus for pouring molten metal, wherein all angles Δθ _N are 10° or more and less than 170°, or all angles Δθ _N are more than -170° and -10° or less. A refractory surrounding pipe arranged to surround the flow of molten metal flowing down from the sliding gate and an intermediate container for containing the molten metal flowing down from the ladle are provided below the sliding gate. Item 2. A molten metal pouring device according to item 1. The inner space of the surrounding pipe has a cylindrical or rectangular horizontal cross-sectional shape,
When the inner diameter of the passage hole of the sliding gate is D, the inner diameter of the surrounding pipe is 3×D or more, and the molten metal flowing down from the ladle is shielded from the atmosphere. 2. The molten metal pouring device according to . Pouring of molten metal according to any one of claims 1 to 3, characterized in that the number of plates forming the sliding gate is two or three and the number of slide plates is one. Device.

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