JP2019188425A - Tundish - Google Patents

Abstract

To provide a tundish capable of suppressing a phenomenon that the efficiency of the floatation separation of inclusions is reduced by a downward flow generated upon the inflow of a molten metal into a tapping chamber.SOLUTION: A tundish 1 comprises: a molten metal receiving chamber 2 injected with a molten metal M; and a molten metal tapping chamber 3 pouring out the molten metal M injected from the molten metal receiving chamber 2. In the tapping chamber 3, an inflow area bottom face 31a as the bottom face of an area including a position into which the molten metal M is made to flow from the molten metal receiving chamber 2 is higher toward the inside of the tapping chamber 3 than a bottom face 31b of the other area.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tundish, and more particularly to a tundish used for floating separation of inclusions in a continuous casting process of a metal material.

  In the process of casting a metal material using a continuous casting apparatus or the like, a tundish is used to perform casting after removing inclusions (impurities such as oxides). The molten metal is poured from the ladle into the tundish, and inclusions float and are separated from the molten metal while the molten metal stays in the tundish. Then, the molten metal is poured from the tundish into the mold with the inclusions removed or reduced.

  As this type of tundish 100, as shown in FIG. 3, a configuration in which a hot water receiving chamber 120 and a hot water discharge chamber 130 are connected by a sleeve 140 is known. Such a tundish having a sleeve is disclosed in Patent Document 1, for example. The molten metal is poured from the ladle into the hot water receiving chamber 120 through the dip tube 170 and flows into the hot water discharge chamber 130 through the sleeve 140. And it pours out to the casting_mold | template from the nozzle hole 180 provided in the bottom face of the hot water supply chamber 130. FIG.

JP, 2006-187812, A

  As shown in FIG. 3, in the tundish 100 having the sleeve 140, as shown in FIG. 4B, the molten metal M that has flowed into the hot water discharge chamber 130 through the sleeve 140 is transferred to the front wall 133 of the hot water supply chamber 130. Collide with the surface. Then, the flow of the molten metal M is divided into the upward flow F2 and the downward flow F3.

  In the tundish 100, the molten metal M flows into the tapping chamber 130 with some of the inclusions contained in the molten metal M injected from the ladle floated and separated in the hot water receiving chamber 120. The inclusions that have not been floated and separated in the hot water receiving chamber 120 ride on the flow of the molten metal M and flow into the hot water chamber 130. When the molten metal M that has flowed into the hot water chamber 130 collides with the front wall 133 to generate the downward flow F3, the inclusions also descend on the downward flow F3 toward the bottom surface 131 of the hot water chamber 130. Then, in the hot water supply chamber 130, further floating separation of inclusions flowing in from the hot water receiving chamber 120 becomes difficult to proceed. If the floating separation of inclusions does not proceed sufficiently in the hot water supply chamber 130, inclusions will be contained in a high concentration in the molten metal M poured out from the nozzle hole 180, and this will affect the quality of the casting. There is a possibility of effect.

  The problem to be solved by the present invention is to provide a tundish that can suppress the decrease in the efficiency of the floating separation of inclusions due to the downward flow generated when the molten metal flows into the tapping chamber. It is in.

  In order to solve the above problems, a tundish according to the present invention includes a hot water receiving chamber into which a molten metal is poured, and a hot water discharge chamber into which the molten metal that has flowed in from the hot water receiving chamber is poured. In the chamber, an inflow region bottom surface, which is a bottom surface of a region including a position where the molten metal flows from the hot water receiving chamber, is higher toward the inside of the hot water discharge chamber than a bottom surface of another region. .

  Here, the hot water receiving chamber and the hot water discharge chamber are connected by a hollow cylindrical sleeve, and the molten metal flows from the hot water receiving chamber into the hot water discharge chamber via the sleeve, and the inflow The region bottom surface may be provided as a bottom surface of a region including an outlet of the molten metal from the sleeve.

  It is preferable that the tundish does not have a dam made of a refractory material that divides a space inside the hot water chamber.

  The bottom surface of the inflow area is flat and preferably parallel to the bottom surface of the other area.

  The bottom surface of the inflow area may be provided so as to occupy the entire area of the tundish along the front-rear direction in which the molten metal flows from the hot water receiving chamber to the hot water discharge chamber.

  The wall surface of the hot water chamber facing the direction in which the molten metal flows into the hot water chamber from the hot water receiving chamber has an inclination in which the lower part is close to the direction in which the molten metal flows and the upper part is away from the direction in which the molten metal flows. It is good to have with respect to the said inflow area bottom face.

  A pair of outlets for pouring out the molten metal is provided on the bottom surface of the hot water chamber across the position where the molten metal flows from the hot water receiving chamber. It is good to be provided in the area | region pinched | interposed into.

  In the tundish according to the above invention, in the hot water discharge chamber, the inflow area bottom surface, which is the bottom surface of the area including the position where the molten metal flows, is higher than the bottom surfaces of the other areas. Therefore, compared with the case where the bottom surface of the inflow region is provided at the same height as the bottom surface of the other region, the distance from the bottom surface of the position where the molten metal that has flowed into the hot water chamber collides with the wall surface of the hot water chamber becomes smaller. As a result, even if the molten metal collides with the wall surface of the tapping chamber, it is difficult for a downward flow to occur. And it becomes easy to generate an upward flow, and the flow rate of the generated upward flow tends to increase. While the downward flow hinders the floating separation of inclusions in the hot water outlet, the floating separation of the inclusions is promoted when the inclusions ride on the upward flow and rise in the molten metal. Therefore, in the hot water discharge chamber, the generation of the downward flow is suppressed, and the generation of the upward flow is promoted, whereby the inclusions can be efficiently separated in the hot water discharge chamber.

  On the other hand, since the bottom surface of the other region is low, unlike the case where the bottom surface of the entire tundish is set at a high position, the capacity of the molten metal stored in the hot water discharge chamber can be secured. As a result, the effect of the floating separation of inclusions can be kept high.

  Here, the hot water receiving chamber and the hot water discharge chamber are connected by a hollow cylindrical sleeve, and the molten metal flows from the hot water receiving chamber to the hot water discharge chamber via the sleeve, and the bottom surface of the inflow area is from the sleeve. In the case where it is provided as the bottom surface of the region including the outlet of the molten metal, since the flow of the molten metal from the hot water receiving chamber to the hot water discharge chamber is performed through a thin sleeve, the molten metal flowing into the hot water discharge chamber is In a rectified state, it collides with the wall surface of the hot water chamber vigorously, and a downward flow is likely to occur as compared with the case where it flows in through the weir instead of the sleeve. However, as described above, by forming the bottom of the inflow region corresponding to the position of the outlet of the sleeve high, it is possible to effectively suppress the occurrence of downward flow. In addition, the inclusions floating and separated in the hot water receiving chamber are less likely to move to the hot water discharge chamber through the sleeve, and by forming the bottom of the inflow area higher, the effect of suppressing the downward flow can be combined. The amount of inclusions mixed in the molten metal poured out from the chamber can be effectively reduced.

  If the tundish does not have a dam made of refractory material that divides the space inside the hot water chamber, the slag formed on the surface of the molten metal can be generated if such a weir is provided. Since the possibility of refractory material erosion due to contact between the layer and the weir is eliminated, labor and cost required for maintenance of the weir can be omitted, and the tundish can be continuously used at a low cost over a long period of time. Also, if there is a weir in the hot water chamber, the weir may disappear or may not be healthy due to melting damage or wear during use of the weir. Since the inclusion floating separation effect due to the inclusion cannot be used, the number of inclusions flowing out from the hot water chamber increases. On the other hand, as described above, the stable quality is ensured in the molten metal poured out from the hot water chamber by not providing the hot water chamber in the hot water chamber and not using the weir for floating separation of inclusions. can do.

  If the bottom surface of the inflow area is flat and parallel to the bottom surface of other areas, the structure of the inflow area is compared to the case where the inflow area has a curved surface structure or an inclined structure with respect to the bottom surface. Due to the fact that the resulting molten metal flow is unlikely to occur, it is possible to effectively suppress the downward flow in the hot water discharge chamber.

  Compared to the case where the bottom surface of the inflow area occupies the entire area of the tundish along the front-rear direction in which the molten metal flows from the hot water receiving chamber to the hot water discharge chamber, as compared with the case where only a partial area is occupied. The occurrence of a downward flow in the hot water chamber can be effectively suppressed.

  The wall surface of the hot water chamber facing the direction in which the molten metal flows into the hot water chamber from the hot water receiving chamber has a slope where the lower part is close to the direction in which the molten metal flows and the upper part is away from the direction in which the molten metal flows. When it has, it will be easy to float an inclusion effectively on the upward flow which a molten metal collides with a wall surface.

  A pair of spouts for pouring the molten metal from the bottom of the hot water chamber is provided across the position where the molten metal flows from the receiving chamber, and the bottom of the inflow area is sandwiched between the pair of spouts. In the case where it is provided in the region, it is possible to effectively reduce the amount of inclusions mixed in the molten metal poured out from the spout without providing an excessively wide bottom surface in the inflow region.

It is a perspective view which shows the outline of the tundish concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the outline of the flow of the molten metal in the said tundish. It is a perspective view which shows the outline of the conventional general tundish. It is a figure explaining the flow of the molten metal which flowed into the tapping room via the sleeve, (a) is a bottom raising structure where the bottom of the inflow area is high, (b) is not high in the bottom of the inflow area The case of the conventional general form which takes a flat structure is shown. It is a simulation result which shows the flow of the molten metal in a tundish, (a) shows the case of the bottom raising structure where the inflow area bottom face became high, (b) shows the case of the flat structure where the inflow area bottom face is not high. Yes. It is a simulation result showing the outflow index of inclusions in the molten metal poured out from the hot water chamber, comparing the case of a raised structure with a raised inflow area bottom and a flat structure without an increase in the particle size of inclusions. Shown for each.

  Hereinafter, a tundish according to an embodiment of the present invention will be described in detail with reference to the drawings.

[Configuration of tundish]
In FIG. 1, the outline of the tundish 1 concerning one Embodiment of this invention is shown. FIG. 2 shows an outline of the flow F of the molten metal M in the tundish 1.

  The tundish 1 according to the present embodiment has a space capable of storing two molten metal M, a hot water receiving chamber 2 and a hot water discharge chamber 3, and is mainly used for continuous casting. In addition, in this specification, about the tundish 1, let the hot water receiving chamber 2 side (back side of the perspective view of FIG. 1) be the back, and let the hot water discharge chamber 3 side (front side of the perspective view of FIG. 1) be the front. In addition, the upper and lower portions in the gravity direction (upper and lower portions in FIG. 1) are defined as upper and lower portions, respectively. And the direction orthogonal to the front-back direction and the up-down direction is defined as the width direction. In the present specification, in terms of the relationship with the direction of gravity and the relative relationship between the members, the terms “parallel”, “center”, “symmetry”, and the like refer to the casting process using the tundish 1 and the inclusions. It is defined as including an error that does not affect the efficiency of flotation separation so as to cause a practical problem.

  Each of the hot water receiving chamber 2 and the hot water discharge chamber 3 is formed as a bottomed container having a wall surface standing on the outer periphery of the bottom surface and opened upward. The hot water reception chamber 2 and the hot water supply chamber 3 have independent bottom surfaces and wall surfaces, respectively, and are partitioned as mutually independent spaces. The hot water reception chamber 2 and the hot water supply chamber 3 are connected and communicated with each other via a sleeve 4.

  The hot water chamber 3 is disposed forward and downward with respect to the hot water receiving chamber 2. Moreover, the hot water receiving chamber 2 and the hot water chamber 3 have a symmetrical shape in the width direction, and the respective positions in the center in the width direction are aligned. The hot water receiving chamber 2, the hot water chamber 3, and the sleeve 4 are formed by joining a refractory made of a metal oxide to an inner wall surface of an outer structure made of iron skin.

  The sleeve 4 is a hollow cylindrical member. In the illustrated embodiment, the sleeve 4 has a cylindrical shape with a shaft extending linearly. In the sleeve 4, an inlet 41, which is a rear end, is joined to a position near the bottom of the wall surface in front of the hot water receiving chamber 2, and communicates with the internal space of the hot water receiving chamber 2. On the other hand, the outlet 42 which is the front end is joined to the wall surface behind the hot water chamber 3 and communicates with the internal space of the hot water chamber 3. Corresponding to the fact that the hot water supply chamber 3 is disposed below the hot water receiving chamber 2, the sleeve 4 is connected to the hot water supply chamber 3 with the inlet 41 side bonded to the hot water receiving chamber 2 positioned upward. The outlet 42 side has a slope that is lowered downward. The number of the sleeves 4 is not particularly limited, but in the illustrated form, the two sleeves 4 are provided symmetrically with respect to the center positions in the width direction of the hot water receiving chamber 2 and the hot water discharge chamber 3.

  The molten metal M flows into the hot water receiving chamber 2 from a ladle (not shown) provided above via a dip tube 7 disposed at the center position. The molten metal M that has flowed into the hot water receiving chamber 2 flows into the hot water discharge chamber 3 through the sleeve 4 as shown as a flow F in FIG. The molten metal M that has flowed into the hot water discharge chamber 3 is poured out from the casting nozzle 8 into a mold (not shown) through nozzle holes (spout ports) 8 a and 8 b provided on the bottom surface 31 of the hot water discharge chamber 3. This tundish 1 is a four-strand type having four nozzle holes 8a and 8b in total. The four nozzle holes 8a and 8b are provided symmetrically on both sides with respect to the position of the center in the width direction of the hot water chamber 3 at two sides. A stopper 6 that can move up and down is provided above the nozzle holes 8a and 8b. The stopper 6 plays a role of starting or stopping discharging of the molten metal M at the start and end of casting of the molten metal M from the nozzle holes 8a and 8b by vertical movement.

  The bottom surface 31 of the hot water chamber 3 includes an inflow region bottom surface 31a provided at the center in the width direction and outer bottom surfaces 31b at both ends in the width direction corresponding to other regions of the inflow region bottom surface 31a. The inflow area bottom surface 31 a is provided as a bottom surface 31 of a region including a position corresponding to the outlets 42 of the two sleeves 4, that is, a position where the molten metal M flows from the hot water receiving chamber 2. As will be described in detail later, the inflow area bottom surface 31a is higher from the outer bottom surface 31b toward the inside of the hot water discharge chamber 3, that is, upward.

  In the illustrated form, the inflow region bottom surface 31a is formed in a region sandwiched between a pair of nozzle holes 8a on the inner side in the width direction among the four nozzle holes 8a and 8b. The inflow area bottom surface 31 a is formed so as to occupy the entire area along the front-rear direction, which is the direction in which the molten metal M flows from the hot water receiving chamber 2 to the hot water chamber 3. The wall surface 33 in front of the hot water chamber 3 is inclined with respect to the inflow area bottom surface 31a. The inclination is formed such that the lower part is the rear (the direction close to the direction in which the molten metal M flows) and the upper part is the front (the direction away from the direction in which the molten metal M flows).

  While the molten metal M stays in the tundish 1, inclusions are floated and separated from the molten metal M. Usually, inclusions such as oxides are mixed in the molten metal M such as molten steel used for continuous casting. In this tundish 1, the molten metal M poured into the hot water receiving chamber 2 contains a relatively large amount of inclusions derived from slag in the ladle. The specific gravity is small, and while the molten metal M stays in the hot water receiving chamber 2, it floats on the surface (hot water surface) of the molten metal M. The inclusions are captured by the slag layer formed on the hot water surface of the hot water receiving chamber 2. In this way, inclusions contained in the molten metal M are floated and separated. Since the inlet 41 of the sleeve 4 is formed in the vicinity of the bottom of the hot water receiving chamber 2, as shown as a flow F in FIG. 2, the molten metal M in the vicinity of the bottom of the hot water receiving chamber 2 where inclusions are reduced due to floating separation. Will flow into the sleeve 4. Therefore, the number density of inclusions in the molten metal M flowing into the hot water discharge chamber 3 through the sleeve 4 is smaller than the number density in the molten metal M injected from the ladle through the dip tube 7.

  Furthermore, also in the hot water chamber 3, the inclusions in the molten metal M float up and are captured by the slag layer on the molten metal surface, so that the separation of the inclusions proceeds. Then, the molten metal M in which the number density of inclusions is further reduced is poured out from the nozzle holes 8 a and 8 b in the bottom surface 31 as compared with the case where it flows into the hot water discharge chamber 3 from the sleeve 4. Thus, the floating separation of inclusions in the hot water receiving chamber 2, the movement of the molten metal M near the bottom of the hot water receiving chamber 2 with few inclusions through the sleeve 4, and the further floating separation of inclusions in the hot water discharge chamber 3 are performed. Then, the molten metal M in which the number density of inclusions is reduced can be poured out from the nozzle holes 8a and 8b as compared with the state in which the hot metal is poured into the hot water receiving chamber 2 from the ladle. As a result, the influence of inclusions can be reduced in the manufactured casting.

[Shape of the hot spring room and separation of inclusions]
In the conventional general tundish 100 such as that disclosed in Document 1, as shown in FIG. 3, the bottom surface 131 of the tapping chamber 130 is formed as a flat surface over the entire area. On the other hand, in the tundish 1 according to the present embodiment shown in FIG. 1, the inflow including the region directly below the position where the molten metal M flows out from the outlet 42 of the sleeve 4 in the bottom surface 31 of the hot water discharge chamber 3. The bottom surface 31a is provided, and has a bottom-up structure that is higher upward than the outer bottom surface 31b, which is another region. By having such a bottom raising structure in the hot water chamber 3, inclusions can be efficiently levitated and separated in the hot water chamber 3. The mechanism is as follows.

  As shown in FIG. 4 (b), since the sleeve 140 (4) is made of a thin tube having an inclination with the front side lowered downward, the hot water discharge chamber 130 (3) from the outlet 142 (42) of the sleeve 140 (4). The molten metal M discharged to the surface forms a flow F1 that moves forward while moving obliquely downward. This flow F1 collides with the front wall 133 (33) of the hot water supply chamber 130 (3). The collided flow F1 generates an upward flow F2 upward from the collision position and a downward flow (short-circuit flow) F3 downward.

  As in the conventional general tundish 100 in FIG. 3, the bottom surface 131 of the hot water supply chamber 130 is flat, and the height of the bottom surface 131 is similar to the other positions at the position where the molten metal M flows from the sleeve 140. 4B, the distance L2 between the outlet 142 of the sleeve 140 and the bottom surface 131 of the hot water chamber 130 becomes longer at the position where the molten metal M flows. Accordingly, the collision position where the flow F1 of the molten metal M collides with the front wall 133 is also a position away from the bottom surface 131. Then, a space in which the molten metal M can flow from the collision position toward the bottom surface 131 is sufficiently present below the collision position. As a result, the descending flow F3 is generated with a relatively large proportion as a ratio with the ascending flow F2.

  Inclusions contained in the molten metal M move on the flow F (F1 to F3) of the molten metal M. The upward flow F2 generated by the collision of the molten metal M with the front wall 133 of the hot water chamber 130 proceeds upward in the direction of the molten metal surface of the molten metal M stored in the hot water chamber 130. Inclusions also float on the upward flow F2 and reach the hot water surface, and are trapped in the slag S layer formed on the hot water surface. Thus, the upward flow F2 promotes the floating separation of inclusions.

  On the other hand, the downward flow F3 proceeds downward toward the bottom surface 131 of the hot water chamber 130. Inclusions riding on the downward flow F3 are conveyed downward in the molten metal M. That is, it sinks downward in the molten metal M. Since the inclusion moves upward along the flow of the molten metal M and cannot reach the molten metal surface, it is difficult to be subjected to floating separation. Thus, the downward flow F3 suppresses the floating separation of inclusions.

  As described above, in the conventional general tundish 100 in which the bottom surface 131 of the hot water discharge chamber 130 is flat, the molten metal discharged from the sleeve 140 due to the distance L2 between the outlet 142 of the sleeve 140 and the bottom surface 131. The rate at which the M flow F1 becomes the downward flow F3 after the collision with the front wall 133 is increased. Further, the ratio of becoming the upward flow F2 becomes low in correspondence with the increase of the ratio of becoming the downward flow F3. The flow rate of the upward flow F2 tends to be small. As a result, it becomes easy to suppress the floating separation of inclusions by the downward flow F3, and the effect of promoting the floating separation of inclusions by the upward flow F2 cannot be fully utilized. Therefore, it is difficult for the inclusions to float and separate in the hot water chamber 130, and it is difficult to sufficiently reduce the concentration of inclusions in the molten metal M poured out from the nozzle holes 180.

  On the other hand, as in the tundish 1 according to the embodiment of the present invention shown in FIG. 1, in the bottom surface 31 of the hot water discharge chamber 3, the inflow region bottom surface 31 a corresponding to the position where the molten metal M flows from the sleeve 4 has another region. In the case of having a bottom raising structure higher than 31b, as shown in FIG. 4 (a), at the position where the molten metal M flows, between the outlet 42 of the sleeve 4 and the bottom surface 31a of the tapping chamber 3 The distance L1 is reduced. Then, as shown in the figure, the flow F1 of the molten metal M discharged from the outlet 42 of the sleeve 4 may collide with the inflow area bottom surface 31a before colliding with the front wall 33 of the hot water discharge chamber 3. In this case, the molten metal M is directed upward from the collision position, and an upward flow F2 is generated. The downward flow F3 is blocked by the inflow area bottom surface 31a and is not substantially generated.

  Even if the flow F1 of the molten metal M discharged from the outlet 42 of the sleeve 4 collides with the front wall 33 of the hot water discharge chamber 3 instead of the inflow area bottom surface 31a, the collision position is from the bottom surface 131 to the sleeve 140. Compared to the case of FIG. 4B where the distance L2 to the outlet 142 is large, the position is low. Then, the space in which the molten metal M can flow from the collision position toward the inflow area bottom surface 31a is reduced, and the downward flow F3 is hardly generated. As described above, since the position of the inflow region bottom surface 31a of the hot water discharge chamber 3 is high, the generation of the downward flow F3 can be suppressed as compared with the case where the inflow region bottom surface 31a is not high. It is also possible not to generate substantially.

  By suppressing the generation of the downward flow F3, it is difficult for the inclusions to ride on the downward flow F3 and sink to the lower side of the molten metal M to suppress the floating separation. Further, in response to the occurrence of the downward flow F3 being suppressed, the proportion of the upward flow F2 is increased, and the flow velocity of the upward flow F2 is also increased. Then, inclusions are likely to reach the hot water surface on the upward flow F2, and the floating separation by being captured by the slag S is promoted. As a result, in the hot water discharge chamber 3, the floating separation of the inclusions proceeds efficiently, and the concentration of inclusions in the molten metal M poured out from the nozzle holes 8a and 8b can be effectively reduced.

  In addition, in the hot water chamber 130 having the flat bottom surface 131 as shown in FIGS. 3 and 4B, the height of the entire flat bottom surface 131 is set to the height of the inflow region bottom surface 31a of FIGS. 1 and 4A. As described above, even if the distance L2 between the sleeve 140 and the outlet 142 of the sleeve 140 is made small, the floating separation of the inclusions can be efficiently performed by the same mechanism as described above with reference to FIG. It is possible to proceed to However, in that case, the entire hot water chamber 130 is formed shallow, and the capacity of the molten metal M that can be stored in the hot water chamber 130 is reduced. Then, the floating separation using the tundish 100 cannot be efficiently advanced. Here, the distance L2 between the outlet 142 of the sleeve 140 and the upper end of the hot water chamber 130 is lengthened while the distance L2 between the flat bottom surface 131 and the outlet 142 of the sleeve 140 is reduced in this way, and the hot water chamber 130 is increased. If the entire depth is ensured, the capacity of the molten metal M that can be stored in the hot water discharge chamber 130 can be ensured, but in this case, the collision F 1 of the molten alloy M collides with the front wall surface 133. Since the distance from the position to the hot water surface is increased, it becomes difficult for the inclusions to reach the hot water surface and be captured by the slag S, and the efficiency of the floating separation of the inclusions is lowered.

  On the other hand, as shown in FIG. 1, only the inflow area bottom surface 31a in the center in the width direction including the area corresponding to the position where the molten metal M flows into the hot water discharge chamber 3 is formed at a high position, and in other areas. By keeping the position of a certain outer bottom surface 31b low, the capacity of the molten metal M that can be stored in the hot water discharge chamber 3 is secured while enjoying the effect of promoting the floating separation of inclusions by the height of the inflow region bottom surface 31a. The efficiency of the casting process using the tundish 1 can be kept high. In this way, it is possible to produce a casting that has both the efficiency of the entire casting process and the efficiency of the floating separation of inclusions and is less affected by inclusions.

  In the tundish hot water discharge chamber 3 according to the present embodiment, the specific shape is not limited as long as the inflow region bottom surface 31a is higher than the outer bottom surface 31b which is another region. However, as shown in the drawing, the bottom surface 31a of the inflow area is formed in a flat shape and is parallel to the outer bottom surface 31b, thereby effectively suppressing the generation of the downward flow F3 and promoting the floating separation of inclusions. can do. If the inflow area bottom surface 31a has a curved surface structure such as a depression or an inclination with respect to the outer bottom surface 31b, the flow of the molten metal M is generated toward the lower portion of the curved surface structure or the inclined structure, and then descends. It may be difficult to suppress the flow F3. On the other hand, by making the inflow area bottom face 31a a simple structure consisting of a plane parallel to the outer bottom face 31b, the occurrence of the flow of the molten metal M due to the structure itself of the inflow area bottom face 31a is suppressed, The ratio of the downward flow F3 to the flow F of the molten metal M in 3 can be effectively reduced.

  Further, in the same manner as described above, from the viewpoint of preventing the flow of the molten metal M caused by the structure itself of the inflow region bottom surface 31a, the inflow region bottom surface 31a preferably has a substantially rectangular outer shape. Further, the surface from which the inflow region bottom surface 31a rises from the outer bottom surface 31b, that is, the side peripheral surface 32 that supports the inflow region bottom surface 31a at the outer peripheral portion is not inclined with respect to the outer bottom surface 31b and is substantially perpendicular to the outer bottom surface 31b. It is preferable to stand up.

  In the hot water discharge chamber 3, the region occupied by the inflow region bottom surface 31 a is not specifically limited as long as it includes a position immediately below the position where the molten metal M flows from the outlet 42 of the sleeve 4 into the hot water discharge chamber 3. . However, as described above, it is preferable to occupy the entire area of the hot water chamber 3 in the front-rear direction. Thereby, generation | occurrence | production of the downward flow F3 can be effectively suppressed in the front-back direction whole region of the hot water delivery chamber 3. FIG. Moreover, regarding the width direction, it is preferable to occupy a region sandwiched between the inner pair of nozzle holes 8a. Since the flow F1 of the molten metal M flowing from the sleeve 4 into the hot water discharge chamber 3 has a certain amount of flow in the width direction, it is very narrow in the vicinity of the outlet 42 of the sleeve 4 in order to effectively suppress the downward flow F3. It is preferable that the inflow area bottom surface 31a is provided not only in the area but also over a certain wide area. However, even if the inflow area bottom surface 31a is provided over the outside of the nozzle hole 8a, the nozzle holes 8a and 8b This is because there is no effect in reducing inclusions in the molten metal M to be poured out.

  The specific height dimension and width direction dimension of the inflow area bottom surface 31a depend on the shape and dimensions of the entire tundish 1, the degree of required floating separation of inclusions, the capacity of the hot water chamber 3 to be secured, and the like. And may be selected as appropriate. As the inflow area bottom surface 31a is made higher, the generation of the downward flow F3 can be suppressed, the flow velocity of the upflow F2 can be increased, and the floating of the inclusion can be promoted. Since the flow velocity of the upward flow F2 becomes too high and the molten metal M passes immediately below the layer of the slag S at a high speed, it is difficult to secure a time sufficient to capture the inclusions with the slag S. Therefore, it is desirable that the height of the inflow area bottom surface 31a is set to a height that can secure the flow velocity of the upward flow F2 that can capture inclusions by the slag S. In addition, ensuring the capacity of the hot water discharge chamber 3 and reducing the inclusions are easy to achieve by not increasing the height of the inflow area bottom surface 31a too much.

  Moreover, in this embodiment, the front wall 33 which opposes the direction in which the molten metal M flows from the hot water receiving chamber 2 in the hot water discharge chamber 3 has an inclination which goes back toward the lower part. Although such an inclination is not necessarily provided, the flow F1 of the molten metal M that collides with the front wall 33 is provided above the front wall 33 by providing at least a position corresponding to the inflow region bottom surface 31a. The angle θ formed with the side becomes larger, and it becomes easier to suppress the generation of the downward flow F3, and it is easy to raise the upward flow F2 toward the hot water surface at a high flow rate. As a result, the efficiency of the floating separation of inclusions can be increased. For example, an embodiment in which the angle formed by the straight line extending the inclination of the sleeve 4 and the upper side of the front wall 33 (approximately equal to the angle θ) is 90 ° or more can be mentioned as a preferable example.

  In the present embodiment, the sleeve 4 is provided with an inclination in which the hot water discharge chamber 3 side is lowered below the hot water reception chamber 2 side. Such an inclination does not necessarily need to be provided, but it is more preferable because the provision of the inclination facilitates a rectifying action when the molten metal M passes through the sleeve 4. Moreover, since the flow F1 of the molten metal M has a component directed downward and proceeds through the hot water discharge chamber 3, the collision position where the flow F1 of the molten metal M collides with the front wall 33 tends to be downward. Furthermore, the flow F1 of the molten metal M easily collides with the inflow area bottom surface 31a, not the front wall 33. Therefore, the generation of the downward flow F3 due to the collision is easily suppressed.

  In the tundish 1 according to the present embodiment, the inflow area bottom surface 31a may be formed higher than the outer bottom surface 31b by any member configuration. For example, by forming a bent structure in which the plate surface is raised upward only in a region corresponding to the inflow region bottom surface 31a on the iron skin itself constituting the outline of the bottom surface 31 of the hot water discharge chamber 3, the height of the inflow region bottom surface 31a is increased. The position can be raised. However, it is possible to easily form the inflow area bottom surface 31a by forming a flat bottom surface over the entire area and placing and fixing a block made of a refractory in a region corresponding to the inflow area bottom surface 31a. . The upper surface of the block is the inflow region bottom surface 31a, and the bottom surface of the region where the block is not placed is the outer bottom surface 31b. The thickness of the block is the difference in height between the inflow area bottom surface 31a and the outer bottom surface 31b. In the case where the inflow area bottom surface 31a is configured in this way, the block is installed on the bottom surface 131 with respect to the conventional general tundish 100 having the hot water discharge chamber 130 whose entire bottom surface 131 is flat as shown in FIG. By simply performing, the tundish 1 according to the embodiment of the present invention can be manufactured easily and at low cost, and the efficiency of the floating separation of inclusions can be achieved.

  In the tundish 1 according to this embodiment, a hot water receiving chamber 2 and a hot water discharge chamber 3 provided independently of each other are connected via a sleeve 4, and the molten metal from the hot water receiving chamber 2 to the hot water discharge chamber 3 is connected. The inflow of M is configured as a separation type tundish that is performed only through the sleeve 4. On the other hand, in a T-type tundish that integrally has a hot water receiving chamber and a hot water discharge chamber, a space between the hot water receiving chamber and the hot water discharge chamber is defined by a planar weir disposed from above and / or below the tundish. An integrated tundish in the form is also used conventionally. Even in the integrated tundish, including the position where the molten metal flows from the hot water receiving chamber into the hot water discharge chamber through the weir, the bottom of the inflow region is set, and at a position higher than the bottom of the other regions of the hot water discharge chamber, By providing the bottom surface of the inflow region, the efficiency of the floating separation of inclusions can be increased by suppressing the downflow generation.

  However, in the separation type tundish 1 as in the present embodiment, the hot water receiving chamber 2 and the hot water discharge chamber 3 are independent, and the inflow of the molten metal M from the hot water receiving chamber 2 to the hot water discharge chamber 3 is the cross-sectional area. Compared with the integrated tundish in which the molten metal M flows from the hot water receiving chamber 2 to the hot water discharge chamber 3 through the wide cross-sectional area defined by the planar weir. Thus, the inclusions floating and separated in the hot water receiving chamber 2 are difficult to move to the hot water chamber 3. For this reason, the concentration of inclusions in the molten metal M poured out from the hot water discharge chamber 3 through the nozzle holes 8a and 8b together with the effect of promoting the floating separation in the hot water discharge chamber 3 by providing the inflow region bottom surface 31a high. Can be effectively reduced. Further, since the molten metal M is rectified by passing through the sleeve 4 having a small cross-sectional area, and vigorously collides with the front wall 33 of the hot water discharge chamber 3, compared with the case where the sleeve 4 is not used. However, if the inflow area bottom surface 31a is provided high, the generation of such a downward flow F3 can be effectively suppressed.

  Moreover, in the weir provided in the integrated tundish, the part located below among the surfaces comes into contact with the molten metal. Then, the site | part which contacts the slag S of a molten metal surface arises in the surface of the refractory material which comprises a weir. As described above, when the slag and the refractory come into contact with each other, the refractory is easily melted by a chemical reaction between them. The weir is attached to the tundish body in a narrow area at the lower edge and side edge, and it is difficult to say that the weir is firmly fixed to the tundish body. It tends to lead to deterioration and damage. Then, it is necessary to frequently replace and repair the weir. On the other hand, in the separation type tundish 1, it is not necessary to use a weir to partition between the hot water receiving chamber 2 and the hot water discharge chamber 3, so that labor and cost required for such replacement and repair are omitted. It becomes possible to continue using the tundish 1 at a low cost for a long period of time.

  In the separation type tundish 1, in order to further promote the floating separation of inclusions, a mode in which a weir for partitioning the internal space is provided in the hot water discharge chamber 3 is also conceivable. From the viewpoint of eliminating the deterioration of the quality of the molten metal M accompanying the increase in the number of inclusions outflow due to the disappearance or malfunction of the weir during production, and from the viewpoint of suppressing the increase in refractory costs due to the installation of the weir, It is preferable not to provide such a weir. As described above, by installing a block-shaped refractory on the bottom surface of the flat tap water chamber 3, the inflow area bottom surface 31a that is higher than the surroundings can be easily formed. Since the entire refractory is installed deep in the molten metal M and does not come into contact with the slag S, the refractory is not substantially damaged by the contact with the slag S as occurs in the case of a weir.

Hereinafter, the present invention will be described more specifically with reference to examples. As an example, in the separated tundish where the hot water receiving chamber and the hot water chamber independent from each other are connected by the sleeve, the height of the bottom surface of the inflow region of the hot water chamber is higher than the outer bottom surface, For the case of the same height, the behavior of molten metal flow and the efficiency of floating separation of inclusions were compared using computer simulation. In addition, this invention is not limited by these Examples.

[Simulation method]
As a model to be analyzed, a tundish having a bottom-up structure in which the bottom surface of the inflow region of the hot water chamber is higher than the bottom surface of the outside as shown in FIG. 1 was prepared. Moreover, the tundish of the flat structure which did not have the inflow area bottom face which became higher than another site | part as shown in FIG. 3, and the bottom face whole area of the tapping room became flat was prepared.

  With respect to the tundish of each model, the state of the flow of the molten metal in the hot water chamber and the behavior of inclusions mixed in the molten metal were analyzed by simulation. Specifically, a molten metal mixed with particles simulating inclusions having a particle size of 30 μm, 50 μm, and 100 μm is injected from the dip tube into the center of the tundish hot water receiving chamber for each model. The route was analyzed. Further, the amount of inclusions contained in the molten metal flowing out from the nozzle holes was analyzed for each particle size. Then, the ratio of the number of inclusions flowing out from the nozzle holes to the number of inclusions mixed in the molten metal poured from the dip tube is calculated, and an index based on the case of a flat structure (inclusion outflow index) It was evaluated in the form of The simulation was performed by a three-dimensional thermal fluid analysis using a finite difference method based on the Navier-Stokes equations. When the inclusions reached the molten metal surface, the inclusions were removed from the molten metal as being captured by the slag.

[simulation result]
In FIG. 5, the flow of the molten metal in the tundish is displayed as a vector diagram. The direction of the vector indicates the direction of flow, and the length of the vector indicates the flow velocity. The figure shows a longitudinal section through the position of the sleeve. FIG. 5 (a) shows a case of a bottom raising structure in which the bottom of the inflow area of the hot water chamber is raised, and FIG. 5 (b) shows a case of a flat structure in which the bottom of the inflow area of the hot water chamber is not high. ing.

  As shown in FIG. 5 (b), in the flat structure in which the bottom of the inflow area is not high, the flow of the molten metal that flows into the hot water discharge chamber from the outlet of the sleeve and collides with the front wall is an upward flow and a downward flow. It is divided into Corresponding to the increase in the distance between the collision position where the molten metal flow collides with the front wall and the bottom surface, the downward flow is generated at a non-negligible ratio compared to the upward flow. I understand.

  On the other hand, as shown in FIG. 5 (a), in the bottom raising structure in which the bottom of the inflow region is raised, the flow of the molten metal that flows into the hot water discharge chamber from the outlet of the sleeve and collides with the front wall is mostly, It is rising. There is very little downflow compared to upflow. Moreover, compared with FIG.5 (b), the length of the vector which goes upwards the vicinity of the front wall of a hot water chamber becomes long, and the flow velocity of an upward flow is rising. These can be associated with the fact that the distance between the collision position where the molten metal flow collides with the front wall and the bottom surface is small.

  Further, FIG. 6 shows a result of comparison of the inclusion outflow index between the bottom-up structure in which the bottom surface of the inflow region is high and the flat structure in which the height is not high. As described above, the inclusion outflow index indicates the outflow ratio of the inclusion in the case of a flat structure as 100% for each particle size.

  As is clear from FIG. 6, in any particle size, the inclusion outflow index is reduced and the outflow amount of inclusions is reduced when the bottom-up structure is adopted than when the flat structure is adopted. . This shows that the floating separation of the inclusions in the hot water chamber is promoted by taking the bottom-up structure. As shown in FIG. 5, by taking the bottom-up structure, the generation of the downward flow is suppressed and the flow rate of the upward flow is increased as compared with the case of adopting the flat structure, and as a result, the intervention on the upward flow It is interpreted that the rising of the object is easy to progress.

  In addition, the inclusion outflow index in the case of the bottom-up structure is lower as the particle size of the inclusion is larger. In particular, when the particle size is 100 μm, the inclusion outflow index is 0%. That is, all the inclusions float and are separated and removed from the molten metal. Coarse inclusions, unlike fine inclusions, have high buoyancy, so they can easily float and separate. On the other hand, if a short-circuit flow (downflow) occurs, it immediately flows out of the nozzle hole. To do. In the result of the above simulation, all the coarse inclusion particles can be floated and separated, which is interpreted as suggesting that the short circuit flow like F3 can be greatly reduced.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

DESCRIPTION OF SYMBOLS 1 Tundish 2 Hot water receiving room 3 Hot water supply room 31 Bottom face 31a of hot water supply room Bottom face 31b Outer bottom face (bottom face of other area)
32 Side peripheral surface 33 at the bottom of the inflow area 4 Front wall of the hot water chamber 4 Sleeve 41 Sleeve inlet 42 Sleeve outlet 7 Dip tube 8 Casting nozzles 8a and 8b Nozzle holes (outlet)
F Flow of molten metal F1 Flow flowing from the sleeve into the tapping chamber F2 Upflow F3 Downflow M Metal melt S Slag

Claims (7)

A hot water receiving chamber into which the molten metal is poured, and a hot water discharge chamber for pouring out the molten metal flowing from the hot water receiving chamber,
In the hot water discharge chamber, an inflow region bottom surface that is a bottom surface of a region including a position where the molten metal flows from the hot water reception chamber is higher toward the inside of the hot water discharge chamber than a bottom surface of another region. Tundish characterized by. The hot water receiving chamber and the hot water discharge chamber are connected by a hollow cylindrical sleeve, and the molten metal flows into the hot water discharge chamber from the hot water receiving chamber through the sleeve,
The tundish according to claim 1, wherein the bottom surface of the inflow region is provided as a bottom surface of a region including an outlet of the molten metal from the sleeve.   The tundish according to claim 1 or 2, wherein the tundish does not have a weir made of a refractory material that divides a space inside the hot water chamber.   The tundish according to any one of claims 1 to 3, wherein the bottom surface of the inflow region has a planar shape and is parallel to the bottom surface of the other region.   The bottom surface of the inflow region is provided so as to occupy the entire area of the tundish along the front-rear direction in which the molten metal flows from the hot water receiving chamber to the hot water discharge chamber. The tundish according to any one of the above.   The wall surface of the hot water chamber facing the direction in which the molten metal flows into the hot water chamber from the hot water receiving chamber has an inclination in which the lower part is close to the direction in which the molten metal flows and the upper part is away from the direction in which the molten metal flows. The tundish according to any one of claims 1 to 5, wherein the tundish is provided with respect to a bottom surface of the inflow region.   A pair of outlets for pouring out the molten metal is provided on the bottom surface of the hot water chamber across the position where the molten metal flows from the hot water receiving chamber. The tundish according to any one of claims 1 to 6, wherein the tundish is provided in a region sandwiched between the spouts.