JP6424706B2 - Sleeve for tundish device and tundish device using the same - Google Patents

Description

  The present invention relates to a sleeve for a tundish device capable of continuously casting a cast piece with few nonmetallic inclusions, and a tundish device using the same.

Continuous casting equipment is equipment for casting molten metal to produce slabs, billets and the like.
In continuous casting, in order to prevent the temperature drop of the molten metal, a technique of stirring the molten metal in a tundish apparatus and a technique of heating the molten metal by induction heating to inject the molten metal in a constant temperature range into the mold. Is used.

  Non-Patent Document 1 discloses a method of performing induction heating and plasma heating for the purpose of setting the temperature of molten metal injected into a mold within a certain range.

In Patent Document 1, a channel is provided between a hot water storage chamber and a hot water storage chamber in a tundish apparatus to move the molten metal, and induction heating is performed using an induction current to suppress a temperature drop of the molten metal. Discloses a method of suppressing the inclusion of non-metallic inclusions.
The outline of the conventional tundish apparatus disclosed in Patent Document 1 and the problems thereof will be described with reference to FIGS.

FIG. 6 is a view for explaining the main flow (hereinafter referred to as "main stream") 20 of molten metal in the conventional tundish apparatus.
6 (a) is a cross-sectional view of the conventional tundish apparatus as viewed from above, and FIG. 6 (b) is a cross-sectional view of the conventional tundish apparatus as viewed from the side.
6 (a) and 6 (b), 1 is a tundish apparatus, 13 is a hot water storage chamber, 14 is a hot water discharge chamber, 15 is a molten metal injection nozzle from a ladle, 16 is an iron core, 17 is an induction coil, 18 is an outlet to the mold, 20 is a mainstream of molten metal, 101 is a conventional sleeve, and 102 is a conventional channel.

  As shown in FIGS. 6 (a) and 6 (b), in the mainstream 20 of molten metal, the molten metal is introduced into the receiving chamber 13 from the molten metal injection nozzle 15 from the ladle, and passes through two conventional channels 102. The molten metal flows into the hot water storage chamber 14, and the molten metal in the necessary amount for casting is supplied from the outlet 18 to the mold. For the purpose of supplying a fixed amount of molten metal to the mold from the outlet 18, for example, the surface of the molten metal in the receiving chamber 13 is slightly higher than the surface of the molten metal in the tapping chamber 14, but Viewed from the whole, it can be treated as almost horizontal as shown in FIG. 6 (b).

Here, as the refractory of the conventional channel 102, the one obtained by hollowing out a cylindrical block in a rectangular block formed using a mold such as a mold is used. A cylindrical hollow space is the main part of the channel.
On the other hand, the tundish is mainly manufactured by stacking refractory materials, and a bathing chamber, a tapping chamber and a partition separating the two chambers are formed. When the partition wall is formed to a certain height, the partition wall is grooved, a sleeve in which a channel is formed is embedded in the groove, and a refractory is further stacked on the groove to manufacture a tundish. That is, the conventional sleeve 101 is mounted in the partition wall of the tundish.

FIG. 8 is a view for explaining a conventional sleeve 101. As shown in FIG.
The sleeve is made of a small diameter nozzle-like cylindrical refractory so as to obtain an appropriate calorific value, and the inner diameter thereof is designed to maximize the calorific value, and is described in FIG. 6 or FIG. Ru.

FIG. 7 is a view for explaining the flow of current based on a cross-sectional view of the conventional tundish apparatus as viewed from above.
In FIG. 7, 1 is a tundish apparatus, 15 is a molten metal injection nozzle from a ladle, 13 is a receiving chamber, 14 is a tapping chamber, 101 is a conventional sleeve, 102 is a conventional channel, 18 is an outlet to a mold, 3 is a direction in which current flows, and an alternating current induced by an induction coil 17 wound around an iron core 16 flows bidirectionally through the receiving chamber 13, the tapping chamber 14 and the channel 102 as indicated by arrows. Thus, the molten metal is heated by the alternating current flowing in both directions.

  However, if the conventional tundish apparatus is provided with the conventional channel 102 and a constant amount of molten metal is supplied to the mold while induction heating is performed by applying an alternating current, the molten metal flowing into the mold is It strongly stirs the nonmetallic inclusions contained, and prevents the nonmetallic inclusions from floating up near the surface of the molten metal and separating it from the molten metal (hereinafter referred to as "floating separation of nonmetallic inclusions"). (Hereinafter referred to as “the problem of inhibition of floating and separation of nonmetallic inclusions”).

Hereinafter, the floating separation inhibition problem of the non-metallic inclusions will be described with reference to FIG.
FIG. 9 (c) is an image diagram for explaining the mechanism by which the outward flow 21 is created when the conventional channel 102 is formed using the conventional sleeve 101.
In FIG. 9C, a strong current flows inside the conventional sleeve 101, whereby a pinching force P3 is generated inside the sleeve 101. Further, since both ends of the sleeve 101 are connected to a wide space such as the hot water receiving chamber 3 or the hot water outlet chamber 4, a strong jet force P2 is generated at both ends of the sleeve 101. The strong injection force P2 is a source of the outward flow 21 generation.

FIG. 9 (b) is a diagram for explaining the outward flow 21 and the inflow 22.
In FIG. 9 (b), the main flow 20 is the flow of molten metal inside the channel, 21 represents the image of the outward flow, and 22 represents the image of the intrusion flow.
Now, since the surface of the molten metal in the receiving chamber 13 is higher than the surface of the molten metal in the tapping chamber 14, a fixed amount of molten metal is supplied to the mold, and the molten metal is in the receiving chamber 13 The fluid flows from the side channel opening (hereinafter referred to as "channel inlet") toward the channel opening on the side of the hot water outlet chamber 14 (hereinafter referred to as "channel outlet") at a constant flow rate.
As a result, an outward flow 21 is generated that is a flow toward the outside of the channel near the central axis at the channel inlet and the channel outlet, and inside the channel near the outer periphery of the channel away from the central axis at the channel inlet and the channel outlet Create an intrusive flow 22 which is a flow towards the
Furthermore, the occurrence of the outward flow 21 will create a "triple" of molten metal when the conventional channel 101 is formed using the conventional sleeve 101. The term "tributary" as used herein refers to a flow of molten metal different from the main stream generated by the outward flow, and is a flow corresponding to the tributary 29 of FIG. 9 (a).

FIG. 9 (a) schematically depicts a half of the tundish device shown in FIGS. 6 to 7, wherein the receiving chamber 13 and the tapping chamber 14 are connected by a conventional sleeve 101 forming a conventional channel 101. A branch 29 of molten metal is depicted before flowing into and out of the conventional channel 102.
Here, the velocity of the outward flow 21 is larger than that of the inflowing flow, and according to the magnetohydrodynamic analysis, the velocity of the outward flow is about 1 to 2 [m / s], and a tributary flow generated due to the outward flow 21 29 inhibits the floatation and separation of nonmetallic inclusions.

  That is, as shown in FIG. 9 (a), at the inlet of the channel, after the outward flow 21 collides with the side wall, the tributary 29 goes to the surface of the molten metal and entrains oxides such as slag floating on the surface of the molten metal. At the outlet of the channel, the tributary 29 branched from the outward flow 21 strongly agitates the nonmetallic inclusions flowing into the mold at the outlet of the channel to cause a phenomenon that the levitation and separation of the nonmetallic inclusion is inhibited.

This phenomenon is caused, in particular, in the case of a continuous casting machine in which the length of the molten metal pool on the channel outlet side is short, the flow on the channel outlet side collides with the side wall caused by collision, or a jet generated by electromagnetic force. The substream 29 generated by the outward flow 21 entraps the slag floating on the surface of the hot water and inhibits the floating and separation of the nonmetallic inclusions.
By incorporating the slag floating on the surface of the hot water by the tributary 29, the manufactured slab contains inclusions.

Japanese Patent Application Laid-Open No. 07-236952

"Recent Trends in Slab Continuous Casting Technology of Steel", The Iron and Steel Institute of Japan, Ed., 153, 154 Nishiyama Memorial Technology Course

  The present invention takes account of the phenomenon that a branch of molten metal causes slag to float on the surface of the molten metal, and when stirring the molten metal by electromagnetic force, it reduces the flow rate of outward flow at the channel inlet and channel outlet It is an object of the present invention to provide a tundish apparatus sleeve capable of suppressing the float separation inhibition of inclusions and reducing the amount of inclusions contained in a manufactured slab and a tundish apparatus having the sleeve for the tundish apparatus.

The inventors evaluated the flow of the molten steel in the tapping chamber by computer simulation, and examined the floating separation effect of nonmetallic inclusions in the molten metal.
As a result, the molten metal jet flow from the channel to the tapping chamber is alleviated, and further, the molten metal flow is prevented from being involved in nonmetallic inclusions by reducing the collision of the molten metal flow with the inner wall of the tundish. The inventors found that there was.

  In addition, the inventors of the present invention promote the floating effect of non-metallic inclusions by raising the molten metal guided to the tapping chamber once to the surface before being tapped from the tapping hole at the bottom of the tapping chamber, ie, , It was found that alleviation of jets, alleviation of wall collisions, and formation of upward flow to the surface of the hot water are important.

  Based on these findings, as a result of further research and development, instead of letting molten metal directly flow into the tapping chamber from the channel outlet, it is with a tapping chamber wall having a channel outlet (hereinafter referred to as "outlet wall"). A sleeve projection (hereinafter referred to as a "sleeve projection") is disposed between a tapping chamber wall (hereinafter referred to as "a relative wall") present at an opposite position, and an opening is formed on the side surface of the sleeve projection. (Hereafter, it is called "opening".) By causing molten metal to flow into the tapping chamber from the opening, a phenomenon in which a branch of the molten metal involves nonmetallic inclusions that have already floated and separated on the surface of the molten metal. The inventors found that generation can be suppressed.

In addition, if the opening is oriented in the direction of the outlet to the mold, the opening tends to flow into the outlet to the mold before the nonmetallic inclusions float and separate to the surface of the molten metal. The present inventors have found that floating and separating nonmetallic inclusions on the surface of the molten metal can be promoted by installing in the opposite direction to the outlet of
The present invention has been made based on the above findings, and the summary thereof is as follows.

(1) A sleeve for a tundish apparatus having a molten metal injection nozzle from a ladle, an outlet to a mold, a hot water receiving chamber, a hot water outlet chamber and a channel connecting these and an induction heating device for flowing an induction current to the channel ,
The tundish device sleeve has a sleeve projection in the tapping chamber,
The side and end portions of the sleeve projection are covered with a refractory,
A part of the side surface of the sleeve projection has an opening oriented at 90 ° to the central axis of the sleeve,
When the inner cross sectional area of the sleeve is S _c and k is a real number, the total area S of the opening is
k · S _c ≦ S (Equation 1)
To satisfy
A sleeve for a tundish device characterized in that

(2) The sleeve for a tundish device according to (1), wherein the k is a real number of 2 or more.

(3) A sleeve for a tundish device according to (1) or (2), including a molten metal injection nozzle from a ladle, an outlet to a mold, a receiving chamber, a tapping chamber, a channel connecting these, and the above A tundish apparatus having an induction heating device for flowing an induction current in a channel, the tundish device comprising
The normal direction of the hot water outlet chamber side wall (hereinafter referred to as "opposite wall") on the opposite side of the hot water outlet as viewed from the sleeve projection is taken as a second reference direction,
A direction connecting a ridge line (hereinafter referred to as “upper corner”) where the central axis of the sleeve, the opposite wall, and the ceiling surface of the hot water discharge room intersect is taken as a first reference direction,
When an angle β (hereinafter referred to as “elevation angle”) between the normal to the opening surface of the sleeve projection and the second reference direction is positive when the direction from the second direction reference to the first direction reference is ,
β> 0 [°] ... (Equation 2)
A tundish apparatus characterized by being.

(4) The tundish apparatus according to (3), wherein
An angle α (hereinafter referred to as “crossing angle”) between the normal line of the opening surface of the sleeve projection and the first reference direction is defined as positive from the first direction reference to the second direction reference. If
0 [°] ≦ α ≦ 45 [°] (Equation 3)
A tundish apparatus characterized by being.

(5) The tundish device according to (4), which has a lower weir formed on the bottom of the tapping chamber and supporting the sleeve projection from below.

  By carrying out continuous casting using the sleeve for the tundish device of the present invention and the tundish device using the same, the non-metallic inclusions are significantly involved while preventing the temperature decrease of the molten metal in the tundish device. It has a remarkable effect of being able to

It is a figure explaining the sleeve for tundish of this invention. FIG. 1 (a) is a schematic view of the sleeve as viewed from the end. FIG. 1 (b1) is a schematic view when a sleeve having a plurality of small circular openings is viewed from the side. FIG. 1 (b 2) is a schematic view of a sleeve having a rectangular opening about half the length of a portion covered with a refractory, as viewed from the side. FIG. 1 (b 3) is a schematic view of a sleeve having a rectangular opening of a length of a portion covered with a refractory when viewed from the side. It is a figure explaining the image in which the molten metal flows through the receiving chamber in the tundish apparatus using the sleeve for tundish of this invention. FIG. 2A is a view schematically showing a state in which the molten metal flowing out of the sleeve follows a wall and a ceiling when there is no lower weir. FIG.2 (b) is the figure which represented typically a mode that the molten metal which flowed out from the sleeve follows a wall and a ceiling, and can flow, when there exists a lower eyelid. It is a figure explaining elevation angle beta of opening, and crossing angle alpha. It is a figure explaining the flow of the molten metal in the tundish apparatus equipped with the sleeve for tundish apparatus of this invention. FIG. 4A is a view for explaining a cross section when the tundish device equipped with the sleeve for tundish device of the present invention is viewed from the top. FIG. 4B is a view for explaining a cross section when the tundish device equipped with the sleeve for the tundish device of the present invention is viewed from the side. It is a figure explaining the flow of the electric current in the tundish apparatus of this invention. It is a figure explaining the mainstream of molten metal in the conventional tundish device. FIG. 6 (a) is a figure for demonstrating the cross section when the conventional tundish apparatus is seen from upper part. FIG. 6 (b) is a view for explaining a cross section when the conventional tundish device is viewed from the side. It is a figure explaining the flow of the current in the conventional tundish apparatus. It is a figure explaining the sleeve with which the conventional tundish apparatus is equipped. It is a figure explaining the substream of the molten metal in the conventional tundish apparatus. Fig.9 (a) is a figure explaining the flow of the molten metal tributary flow at the time of using the conventional tundish apparatus. FIG. 9 (b) is a diagram for explaining the outward flow 21 and the inflow 22. FIG. 9 (c) is a view for explaining the mechanism for creating the outward flow 21 when the conventional channel 102 is formed using the conventional sleeve 101.

First Embodiment
A first embodiment of the present invention is a sleeve for a tundish device.
The tundish apparatus is a tundish apparatus having a molten metal injection nozzle from a ladle, an outlet to a mold, a hot water receiving chamber, a hot water outlet chamber, a channel connecting these, and an induction heating device for flowing an induction current to the channel.

Tundish device sleeve of the present invention, one side surface and the end of the sleeve is covered with refractory material, an opening in said covered with refractory portion, the inner cross-sectional area of the sleeve S _c, real number k When making the opening in the refractory covered side of the sleeve, the total area S of the opening is
k · S _c ≦ S (Equation 1)
Satisfy.

Here, the total opening area S means the area when there is one opening and the total value of the areas when there are a plurality of openings.
Conventionally, as shown in FIGS. 8 and 9, the sleeve only forms a channel inside the partition separating the hot and cold storage chamber in the tundish, but the sleeve of the present invention only forms a channel. Rather, it protrudes inside the tapping chamber, and the opening is formed on the side surface thereof, and has a portion of the sleeve projecting into the tapping chamber (hereinafter referred to as a "sleeve projection").

FIG. 1 is a view for explaining a sleeve for a tundish device of the present invention.
FIG. 1 (a) is a schematic view of the sleeve as viewed from the end.
In FIG. 1A, 111 is a sleeve tube, 112 is a refractory, and 113 is a sleeve projection. In order to explain variations of the sleeve, different aspects of the A-A cross section of FIG. 1 (a) are described in FIG. 1 (b1), FIG. 1 (b2) and FIG. 1 (b3).

  FIG. 1 (b1) is a schematic view when a sleeve having a plurality of small circular openings is viewed from the side. In FIG. 1 (b1), 111 is a sleeve tube, 112 is a refractory, and 4 is an opening.

  FIG. 1 (b 2) is a schematic view of a sleeve having a rectangular opening about half the length of a portion covered with a refractory, as viewed from the side. In FIG. 1 (b 2), 111 is a sleeve tube, 112 is a refractory, and 4 is an opening.

  FIG. 1 (b 3) is a schematic view of a sleeve having a rectangular opening of a length of a portion covered with a refractory when viewed from the side. In FIG. 1 (b 3), 111 is a sleeve tube, 112 is a refractory, and 4 is an opening.

  The sleeve for a tundish device according to the present invention is made of a refractory material, a prismatic sleeve is formed using a mold, the side opening is machined, and the sleeve is a partition wall of tundish by the same method as a conventional sleeve. The tundish device having the sleeve for a tanschash device according to the present invention is configured by being embedded in a portion (a partition portion between a bathing chamber and a tapping chamber).

Although this embodiment has a prismatic shape for ease of manufacture, it may have a cylindrical shape. Further, the space inside the sleeve 11 that forms the channel 12 may be formed when molding using a mold, or may be machined to form the inner space after molding into a packed shape inside.
The operation and effect when the sleeve for the tundish device of the present invention is used will be described in detail in the second embodiment.

Second Embodiment
A second embodiment of the present invention is a tundish apparatus provided with the sleeve of the present invention manufactured in the first embodiment.

[Flow of molten metal in the receiving chamber]
The flow of the molten metal in the hot water receiving chamber in the tundish apparatus using the tundish apparatus sleeve of the present invention will be described with reference to FIG.
FIG. 2 is a view for explaining an image of molten metal flowing in a tundish apparatus using the tundish sleeve of the present invention.
In FIG. 2, 11 is a sleeve, 113 is a sleeve projection, 12 is a channel, 13 is a receiving chamber, 14 is a tapping chamber, and 15 is a molten metal injection nozzle from a ladle 18 is an outlet to the mold, 19 is a lower weir, and thick arrows indicate the flow direction of the molten metal.
Fig.2 (a) is a case where there is no lower weir 19 and Fig.2 (b) is a case where there is a lower weir 19 that molten metal flowing out from the sleeve can flow through the wall and ceiling. FIG.
With or without the lower weir 19, the molten metal flows along the wall and ceiling of the outlet chamber after flowing out of the sleeve projection 113, and flows into the outlet 18 to the mold, thereby alleviating so-called jets. It has been found that it is possible to suppress the occurrence of the phenomenon in which non-metallic inclusions, which are separated and floated on the surface of the molten metal, are taken into account, as shown in FIG. 9 (a).

[Relaxation of jet]
The inventors pay attention to the fact that the flow velocity is approximately in inverse proportion to the cross-sectional area, and due to the structure in which the molten metal flows out from the opening, the outward flow 21 as shown in FIG. It has been found that it is possible to suppress the generation of the branch flow 29 and to suppress the occurrence of the phenomenon in which the molten metal branch flow-in involves the non-metallic inclusions that have already floated and separated on the surface of the molten metal.
That is, although the outward flow 21 and the inflowing flow 22 are conventionally generated at the outlet of the sleeve as illustrated in FIG. 9B, by mounting the sleeve for the tundish device of the present invention, FIG. The occurrence of the outward flow 21 and the intrusive flow 22 as depicted in 2.) is sharply reduced. That is, the jet flow of the molten metal flow can be softened.

The flow velocity is reduced by extending the sleeve of the channel, providing the sleeve projection, providing an opening serving as the outlet of the molten metal on the side surface of the sleeve projection, and making the total area of the opening larger than the cross sectional area of the sleeve. It was found that the outward flow 21 was mitigated.
From this point of view, the inventors have conducted extensive research results, the openings the total area of the sleeve projection at least twice the sleeve cross-sectional area S _c, preferably, is 4 times or more, the total area of the condition It has been found that the number and shape of the openings may be arbitrary, as long as

That is, the opening is formed on the refractory covered side of the sleeve, and the total area S of the opening is
k · S _c ≦ S (Equation 1)
If k is satisfied, k is preferably a real number of 2 or more, and more preferably, k is a real number of 4 or more. The upper limit of k is not particularly set, but is set to 10 in order to sufficiently reduce the flow velocity of the molten metal inside the sleeve projection. The preferred upper limit is 7.

Further, as the form of the opening, as shown in FIG. 1 (b1), a large number of circular openings may be provided, or as shown in FIG. 1 (b1) to (b2), a single opening may be provided in a slit shape. Good.
Further, the molten metal flowing out from the opening has a high flow velocity toward the root of the sleeve projection, and the flow velocity is relaxed as it approaches the tip of the sleeve projection. That is, the molten metal flow out of the opening is a non-uniform flow. It is preferable to increase the uniformity of the molten metal flow from the viewpoint of inclusion removal, the life of the tundish, and the like. In order to enhance the uniformity of the molten metal flow, the opening at the base of the sleeve projection may be made as large as it approaches the tip within the range satisfying (Equation 1).

[Relaxation of circulation by lower layer]
Next, the case where there is a lower eyelid will be described.
A part of the molten metal may not circulate out of the outlet 18 to the mold, and a circulating flow (hereinafter referred to as “recirculating flow”) may occur again on the upward flow, and the circulating flow is a sleeve projecting In some cases, non-metallic inclusions contained in the molten metal discharged from the portion 113 may be newly caught, and the cleanliness of the molten metal is lowered.
Therefore, the inventors have found that by inhibiting such circulating flow by the lower layer, a cleaner molten metal can be rapidly drained to the mold.

[Installation Procedure of Sleeve for Tundish Device of the Present Invention]
The sleeve of the present invention described in the first embodiment is mounted on a tundish device, and the opening provided on the side surface of the sleeve projection has an opening elevation angle β, which will be described later, β> 0 [°] ... (Formula 2)
age,
The opening intersection angle α, which will be described later, is defined based on the direction connecting the channel outlet and the upper corner of the opposite wall as 0 [°] ≦ α ≦ 45 [°] (Equation 3)
Equip to the angle of

This will be described below with reference to FIG.
FIG. 3 is a view for explaining the elevation angle β of the opening and the crossing angle α.

[Aperture angle β]
In FIG. 3, 14 is a pouring chamber, 142 is an opposite wall, 11 is a sleeve of the present invention, 114 is a center of the opening cross section, 43 is a normal direction of the opening, and 52 is the opposite. A second reference direction indicating the normal direction to the wall, 44 is the opening elevation angle β.
The opening elevation angle β is measured assuming that the direction from the second direction reference to the first direction reference is positive. That is, when the opening normal direction 43 coincides with the second reference direction 141, β = 0 [°], and by setting β> 0, the effects of the present invention can be obtained.
The opening elevation angle β may be slightly upward. That is, the opening normal 43 may be between the second reference direction and the second reference direction. At this time, since an upward flow occurs, an inclusion separation effect is exhibited. Therefore, it is desirable that the opening elevation angle β be β> 0 °.

[Aperture Crossing Angle α]
Furthermore, in FIG. 3, 14 is a hot water outlet chamber, 141 is an upper corner consisting of a ridge line of the opposite wall and the ceiling surface, 11 is a sleeve of the present invention, 114 is a cross section center of the opening, Is a normal direction of the opening, 51 is a first reference direction indicating the direction of the upper corner from the opening, and 42 is an opening crossing angle α.
The opening intersection angle α is measured on the assumption that the direction from the first direction reference to the second direction reference is opposite to the elevation angle β. That is, when the opening normal direction 43 coincides with the first reference direction 141, α = 0 °. It has been confirmed that the effect of the present invention is further increased by setting α ≧ 0.
The opening intersection angle 42 (α) is set to 0 [°] to 45 [°] for the following reason.

First, the lower limit value will be described.
Opening Crossing Angle α A value smaller than 0 ° with respect to the direction of the corner of the wall of the receiving chamber, that is, when the opening is directed to the ceiling wall 143 corresponding to the ceiling of the receiving chamber, inclusions It is because it will inhibit the emergence of

Next, the upper limit value will be described.
Basically, the opening does not have to be directed directly to the opposite wall, and any upward angle is sufficient. It is known that when the openings are directly facing the opposite wall, the effect of the opening crossing angle can be greatest.
This maximum angle will be different if the dimensions of the pouring chamber are different. In addition, since the flow of the molten metal in the tapping chamber is also different, the inclusion removal effect may be inferior if the opening is upward only, but if the opening intersection angle α is increased, the inclusion is directed to the exit of the mold The tendency to flow is higher.
Therefore, the opening intersection angle α is set to 45 ° or less regardless of the dimensions of the tapping chamber.

  In this way, the molten metal flow flowing out of the opening has the upward component of the flow velocity by the effect of the crossing angle, and the proportion of the flow vertically colliding with the inner wall of the tundish is reduced. That is, the severity of the collision against the inner wall of the tundish is alleviated. As a result, the formation of turbulent flow and vortices is suppressed, and the inclusion of nonmetallic inclusions is suppressed.

  Further, since the molten metal that has reached the vicinity of the surface of the molten metal subsequently becomes a downward flow and flows out from the outlet 18 to the mold toward the mold, the crossing angle α is 0 [°] to 45 [°]. The formation of the upward flow is promoted, and the formation of the upward flow increases the proportion of the molten metal flow reaching the vicinity of the surface of the molten metal, thereby promoting the effect of separating nonmetallic inclusions in the vicinity of the surface of the molten metal.

[下 堰]
Furthermore, if necessary, for example, a lower weir 19 as shown in FIG. 2 (b) is provided on the tapping chamber bottom 144 of FIG.
As shown in FIG. 2, the upper end of the lower rod 19 and the sleeve projection 113 may or may not be in contact with each other. When the upper end of the lower weir 19 and the sleeve projection 113 are not in contact with each other, the blocking effect of the circulating flow is reduced to some extent, but the inclusion of nonmetallic inclusions in the circulating flow is reduced to improve the cleanliness of the molten metal.

[Flow of molten metal in tundish apparatus]
The flow of molten metal in the tundish apparatus equipped with the inventive tundish described in the first embodiment will be described with reference to FIG.

FIG. 4 is a view for explaining the flow of molten metal in a tundish apparatus equipped with the tundish sleeve of the present invention.
FIG. 4 (a) is a view for explaining a cross section when the tundish device of the present invention is viewed from the top, and FIG. 4 (b) is a view when the tundish device of the present invention is viewed from the side. It is a figure for demonstrating a cross section.

In FIG. 4, 1 is a tundish apparatus, 11 is a sleeve of the present invention, 12 is a channel, 13 is a receiving chamber, 14 is a tapping chamber, and 15 is a molten metal from a ladle The injection nozzle 16 is an iron core, 17 is an induction coil, 18 is an outlet to the mold, and 20 is a direction in which the molten metal flows.
The molten metal flowing from the ladle into the hot water supply chamber 13 from the molten metal injection nozzle 15 flows through the sleeve 11 provided in the channel 12 and flows out from the sleeve protrusion 113 into the hot water discharge chamber 14 and is discharged to the mold 18. Flow into

  In FIG. 4, the tip of the sleeve projection 113 is in contact with the opposing inner wall of the tundish, but the sleeve projection may be shorter and the tip may not be in contact with the inner wall of the point dish.

It should be noted that although the sleeves 11 provided in the two sets of channels 12 are illustrated in FIG. 4, only the sleeves 11 provided in the one set of channels 12 are illustrated in FIG. 1.
Each of the sleeves 11 mounted in the two sets of channels 12 depicted in FIG. 4 has the same function, so it suffices to describe one.
Therefore, in FIG. 1, in order to focus on one of the sleeves 11 provided in the two sets of channels 12 depicted in FIG. 4, the two sets of channels 12 depicted in FIG. One of the equipped sleeves 11 is depicted.

[Current flow in the tundish device]
The flow of current in the tundish apparatus having the tundish sleeve of the present invention will be described with reference to FIG.
FIG. 5 is a view for explaining the flow of current in the tundish apparatus having the tundish sleeve of the present invention.
In FIG. 5, 1 is a tundish apparatus, 11 is a sleeve of the present invention, 11 is a channel, 13 is a receiving chamber, 14 is a tapping chamber, and 15 is a molten metal from a ladle An injection nozzle, 16 is an iron core, 17 is an induction coil, 18 is an outlet to a mold, and 3 is a direction of current flow.
In the tundish apparatus having the tundish sleeve of the present invention, the current flows as shown in the direction 3 in which the current flows in FIG.

[Securing Joule heat]
The electrical resistance in the sleeve is inversely proportional to the cross-sectional area of the sleeve and proportional to the length, resulting in a large resistance. Therefore, when the power supply voltage is fixed, it is conceivable that the current value is lowered, the Joule heat is decreased, and the heating capacity is decreased.
Therefore, the inventors have found that it is effective to provide a detour for the current by providing an opening having an area equal to the cross-sectional area of the sleeve on the side surface of the sleeve in order to avoid a decrease in heating capacity. The

However, at the opening of the sleeve projection through which the main flow passes, the flow velocity is 1 to 2 [m / s] if the same as the sleeve cross-sectional area, and if the flow velocity is directed to the hot water surface The collision velocity on the surface of the hot water increases, which may inhibit the floating of inclusions.
On the other hand, the critical flow velocity at which non-metallic inclusions floating on the surface of molten steel are caught in the molten steel is said to be about 0.5 to 0.7 [m / s].
Therefore, by making the total area of the opening satisfy (Equation 1), the flow velocity of the main flow is suppressed to about 0.5 to 0.7 [m / s] to promote the floating of inclusions while securing the Joule heat. .

[Continuous casting equipment]
A 30 [t] tundish for 1-strand casting is provided with two cylindrical induction heating channel sleeves with a length of 1 [m] and a diameter of 12 [cm], and molten steel is poured from a ladle through a nozzle The hot water receiving chamber is connected to the hot water receiving chamber on the side where the molten steel is poured into the mold.
An iron core and an induction coil are installed around the channel as shown in the figure, so that an induced current flows in the channel. A current of 0.7 MW is applied to raise the molten steel temperature from the hot water storage chamber to the hot water discharge chamber by about 30 ° C.

[Comparative example]
No. 1 which is a comparative example. 1 is the case where casting is performed using a conventional sleeve that does not have an extension sleeve protrusion.

[Invention Example]
Example No. 1 of the present invention. 2-No. 15 is a case where casting is performed using the sleeve for a tundish apparatus of this invention.
The opening total area ratio 1, 2, 3, 4 means that the total opening area is 1 time, 2 times, 3 times, 4 times the cross sectional area of the sleeve.
The number of outlet holes is the number of holes to be the outlet.
That is, no. 2-No. The relationship between the total area ratio of openings and the number of exit holes of 10 is as follows.
No. 2 is a case where the number of outlet holes is one and the area of the outlet holes is equal to the cross sectional area in the sleeve.
No. 3 is a case where the number of outlet holes is one, and the area of the outlet holes has an area twice the cross sectional area in the sleeve.
No. 4 is a case where the number of outlet holes is two, and the area of each outlet hole has an area equal to the cross sectional area in the sleeve.
No. 5 is a case where the number of outlet holes is one, and the area of the outlet holes has an area three times the cross sectional area in the sleeve.
No. 6 is a case where the number of outlet holes is three, and the area of each outlet hole is equal to the cross-sectional area in the sleeve.
No. 7 is a case where the number of exit holes is one, and the area of the exit holes has an area four times the cross sectional area in the sleeve.
No. 8 is a case where the number of outlet holes is four, and the area of each outlet hole has an area equal to the cross sectional area in the sleeve.
No. 9 is a case where the number of outlet holes is one, and the area of the outlet holes has an area five times the cross sectional area in the sleeve.
No. 10 is a case where the number of outlet holes is five, and the area of each outlet hole has an area equal to the cross-sectional area in the sleeve.
Also, no. 11 to No. In the case where the number of outlet holes is one and the area of the outlet holes is twice the area of the cross sectional area of the sleeve, the opening cross angle [° ] Are respectively made into -5 [degree], 50 [degree], 20 [degree], 40 [degree], and 30 [degree].

[Evaluation method]
The effect is to observe the cross section of the sample microscopically and count the number of non-metallic inclusions of 10 [μm] or more in the same visual field area, and also microscopically observe the cross section of the sample collected in the mold The number of non-metallic inclusions having a diameter of 10 [μm] or more was counted to evaluate floating separation in the tundish. Here, the diameter of the inclusions was determined as the equivalent circular diameter. Specifically, the effect of floating separation was evaluated by the ratio to the number of nonmetallic inclusions counted by the same method in the case of using a conventional tundish not having a sleeve projection.

The nonmetallic inclusions were classified into spherical ones that were in a molten state in molten steel and alumina-based inclusions in which alumina of several [μm] diameter was aggregated because of low melting point called slag type.
The slag-based inclusions are those in which the slag flowing from the ladle into the receiving chamber and floating on the surface of the hot water is caught in the molten steel by the molten steel flow.
No. The number of alumina inclusions in the case of the comparative example 1 and the number of slag inclusions as a reference “1”, the value expressing the amount by ratio is respectively the alumina inclusion number index, the slag inclusions It is a number index.

  The evaluation in the case where both the alumina-based inclusion number index and the slag-based inclusion number index were 0.8 or less was regarded as excellent (優良). In the case where the alumina-based inclusion number index is more than 0.8 and 0.90 or less and the slag-based inclusion number index is 0.80 or less, the evaluation is good (o). Other than that, it was considered as rejection (x). All of the inventive examples were ◎ or ○.

  The sleeve for the tundish device and the tundish device produced by the production method of the present invention and the tundish device of the present invention can be used in continuous casting of molten metal.

  1: Tundish device, 11: sleeve of the present invention, 111: sleeve tube, 112: refractory, 113: sleeve projection, 114: central axis of sleeve, 12: channel, 13: receiving chamber, 14: tapping chamber , 141: upper corner of opposite wall, 142: opposite wall, 143: ceiling wall, 144: bottom of pouring chamber, 15: molten metal injection nozzle from ladle, 16: iron core, 17: induction coil, 18: to mold Outlet, 19: Lower rod, 2: Direction of flow of molten metal, 20: Main flow of molten metal, 21: Outflow, 22: Invasive flow, 29: Branch of molten metal 3: Direction of flow of electric current, 4: Opening , 42: opening intersection angle α, 43: opening normal, 44: opening elevation β, 5: reference plane, 51: first reference direction, 52: second reference direction, 101: conventional sleeve, 102: Conventional channel, P1: Molten metal static pressure , P2: injection force, P3: electromagnetic contraction force.

Claims (5)

A sleeve for a tundish apparatus having a molten metal injection nozzle from a ladle, an outlet to a mold, a receiving chamber, a tapping chamber, a channel connecting these, and an induction heating device for flowing an induction current to the channel,
The tundish device sleeve has a sleeve projection in the tapping chamber,
The side and end portions of the sleeve projection are covered with a refractory,
A part of the side surface of the sleeve projection has an opening oriented at 90 ° to the central axis of the sleeve,
When the inner cross sectional area of the sleeve is S _c and k is a real number, the total area S of the opening is
k · S _c ≦ S (Equation 1)
To satisfy
A sleeve for a tundish device characterized in that   The sleeve for a tundish device according to claim 1, wherein the k is a real number of 2 or more. A sleeve for a tundish device according to claim 1 or claim 2, comprising a molten metal injection nozzle from a ladle, an outlet to a mold, a receiving chamber, a tapping chamber, a channel connecting these, and induction to the channel A tundish apparatus having an induction heating apparatus for passing an electric current, the apparatus comprising:
The normal direction of the hot water outlet chamber side wall (hereinafter referred to as "opposite wall") on the opposite side of the hot water outlet as viewed from the sleeve projection is taken as a second reference direction,
A direction connecting a ridge line (hereinafter referred to as “upper corner”) where the central axis of the sleeve, the opposite wall, and the ceiling surface of the hot water discharge room intersect is taken as a first reference direction,
When an angle β (hereinafter referred to as “elevation angle”) between the normal to the opening surface of the sleeve projection and the second reference direction is positive when the direction from the second direction reference to the first direction reference is ,
β> 0 [°] ... (Equation 2)
A tundish apparatus characterized by being. The tundish apparatus according to claim 3, wherein
An angle α (hereinafter referred to as “crossing angle”) between the normal line of the opening surface of the sleeve projection and the first reference direction is defined as positive from the first direction reference to the second direction reference. If
0 [°] ≦ α ≦ 45 [°] (Equation 3)
A tundish apparatus characterized by being.   The tundish device according to claim 4, further comprising a lower weir formed on the bottom of the pouring chamber and supporting the sleeve projection from below.

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