JP2017094333A - Tundish for continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tundish for continuous casting for maintaining a molten steel temperature of an injection port as much as possible just after starting molten steel supply from a ladle, and reducing a molten steel temperature difference between a plurality of injection ports (strands) as much as possible.SOLUTION: In a tundish 10 for continuous casting, a molten steel distribution chamber 12 is formed with molten steel passage parts 26a, 26b for guiding to injection ports 21a, 21c of at least the most outside (the tail end part) among a plurality of injection ports 21a-21c and molten steel reservoir parts 28a, 28c for surrounding the injection ports 21a, 21c of the tail end part, and first of all, molten steel of flowing in from a molten steel receiving chamber 11 is preferentially made to flow to the injection ports 21a, 21c on the outside of the molten steel distribution chamber 12, and afterwards, the molten steel is flowed at a stretch toward the injection port 21b of a central part, to thereby restrain a variation in a molten steel temperature difference between the injection ports 21a-21c and reduction in a molten steel temperature of the injection ports 21a, 21c of the tail end part.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a tundish used in a continuous casting apparatus capable of casting a plurality of slabs simultaneously, and more particularly to a novel tundish for continuous casting suitable for making the temperature of molten steel flowing through each inlet more uniform.

  Conventionally, in continuous casting of steel, steel is discharged from a converter or electric furnace to a ladle, and molten steel whose ingredients and temperature are adjusted in the ladle is supplied to the tundish, which is an intermediate container, through an injection nozzle. The continuous casting of steel that is temporarily retained in the tundish and then fed into the mold through an immersion nozzle is widely known.

  In the above tundish structure, generally, a molten steel receiving chamber in which molten steel is supplied from above from a ladle, a molten steel distribution chamber for supplying molten steel supplied to the molten steel receiving chamber to a lower mold, The molten steel distribution chamber and the molten steel receiving chamber are partitioned to partition the molten steel temporarily and then flow into the molten steel distribution chamber.

  In addition to having the function of supplying the molten steel from the ladle to the mold, the tundish is inevitably mixed during steel refining by temporarily retaining a predetermined amount of molten steel in the tundish. It also has the function of floating and separating non-metallic inclusions such as alumina produced from slag, which is an oxide, or aluminum added for deoxidation.

  By the way, when the structure of the tundish is a structure corresponding to multiple strands in which a plurality of cast pieces are cast at a time, a plurality of inlets connected to a plurality of molds are formed in the molten steel distribution chamber. Among these, for example, as shown in FIG. 9, in the case where the number of strands is a plurality of 3 or the like, the injection ports are provided at the central portion near the partition portion of the molten steel distribution chamber and at both ends in the longitudinal direction of the molten steel distribution chamber. Become. In this case, paying attention to the flow of the molten steel immediately after the start of the molten steel supply from the ladle, first, the molten steel supplied to the molten steel receiving chamber flows into the vicinity of the central inlet near the partition portion of the molten steel distribution chamber. After filling this central portion of the inlet, the molten steel gradually flows toward the vicinity of the inlet located at both ends (terminal portions) in the longitudinal direction of the molten steel distribution chamber. Many conventional tundishes have a structure in which such a flow of molten steel occurs.

  However, since the temperature of the molten steel supplied to the tundish gradually decreases with time due to heat dissipation and heat transfer to the refractory while flowing in the tundish, a large molten steel temperature difference occurs between the inlets (strands). There is a case. In particular, in the case of the structure in which molten steel is poured into both the inlet located at the center of the molten steel distribution chamber and the inlets located at both ends of the molten steel distribution chamber as described above, the former inlet and the latter inlet Then, because there is a difference in the time to reach the injection port, the temperature of the molten steel flowing to the injection ports at both ends is significantly lower than the injection port at the center, and nozzle clogging occurs at the beginning of casting. There's a problem.

  Therefore, in order to solve the above-described problem, conventionally, there is known a technique for suppressing variations in molten steel temperature between the inlets by changing the flow direction of molten steel when flowing into the molten steel distribution chamber. For example, in the tundish of Patent Document 1, a hot water hole is formed in a partition weir between a molten steel hot water receiving chamber and a molten steel distribution chamber, and the direction of the hot water hole is an inlet at the center of the molten steel distribution chamber and an inlet adjacent thereto. A structure is disclosed in which variations in molten steel temperature between the inlets are suppressed as much as possible by flowing the molten steel flowing from the molten metal hole so as to branch between adjacent inlets. Patent Document 1 also discloses a structure in which the flow rate of the molten steel toward the injection port at the end portion is increased by narrowing the both side portions in the longitudinal direction of the molten steel distribution chamber toward the outside.

JP 2014-113634 A

  However, the tundish structure of Patent Document 1 is a structure in which molten steel flows between an inlet located in the center of the molten steel distribution chamber and an inlet adjacent thereto, but is filled with molten steel. The order of the entrances (strands) is not particularly controlled. When the order of the inlets through which the molten steel flows is not controlled, there is a large difference in molten steel temperature between the inlet where the molten steel reaches first and the inlet where the molten steel finally arrives at the start of casting when the molten steel is supplied to the mold. May have occurred.

  That is, in the conventional structure including the tundish of Patent Document 1, the molten steel flowing out of the molten metal immediately after the start of the molten steel supply from the ladle flows in a divergent form on the bottom surface of the molten steel distribution chamber. In addition to the increased contact area, the flow rate of the molten steel also decreases, so that there is a problem that the temperature decrease increases due to heat dissipation and heat transfer to the refractory while the molten steel reaches the inlet.

  In particular, since the inlet of the end portion also has a longer flow path from the molten metal hole, even if the molten steel flows between adjacent inlets as described above immediately after the start of supplying molten steel, it reaches the inlet of the end portion. It takes time until the difference between the molten steel temperature at the inlet located at the center and the molten steel temperature at the inlet located at the end increases, and the problem of nozzle clogging still remains. Further, since the tundish immediately after the start of the molten steel supply is in a low temperature state, there is also a problem that the molten steel temperature of the inlet filled first is lowered before all the inlets are filled with molten steel.

  The present invention has been made in view of such a background, and maintains the molten steel temperature at the inlet immediately after the start of feeding molten steel from the ladle as much as possible and continuously reduces the molten steel temperature difference between the plurality of inlets (strands). It is intended to provide a tundish for casting.

  In order to solve the above problems, the inventors of the present invention controlled the order of filling the inlet with molten steel, and after flowing the molten steel preferentially to the outer (terminal) inlet, immediately into the central inlet. Focused on the technical idea of flowing. As a result of further research and development, the molten steel distribution chamber is connected to a molten steel passage portion that leads to the outermost (terminal) inlet of the plurality of inlets, and the molten steel passage portion is connected to the molten steel passage portion. By forming the molten steel pool surrounding the inlet, the present invention has been achieved by suppressing variations in the molten steel temperature difference between the inlets and reducing the molten steel temperature at the inlet at the end.

  The continuous casting tundish of the present invention (first invention according to claim 1) obtained as a result of the above examination is supplied to a molten steel receiving chamber to which molten steel is supplied from a ladle and to this molten steel receiving chamber. In a tundish for continuous casting comprising a molten steel distribution chamber for supplying the molten steel to a plurality of molds, and a partition portion for partitioning between the molten steel distribution chamber and the molten steel receiving chamber, the molten steel distribution chamber has a longitudinal length. A plurality of inlets are formed at predetermined intervals in the direction, and a molten steel flow part that is provided in the partition part and allows a part of the molten steel to flow from the molten steel receiving chamber to the molten steel distribution chamber, A molten steel passage section extending from the vicinity of the molten steel circulation section toward the outer side in the longitudinal direction of the molten steel distribution chamber from the arrangement row comprising the plurality of inlets, and connected to the molten steel passage section, and At least the outer inlet of the plurality of inlets For, is characterized in that a concave molten steel reservoir surrounding the inlet.

  The tundish for continuous casting according to the present invention (the second invention according to claim 2) is the first or second invention, wherein the wall portion on the inlet side of the molten steel passage portion is formed from the bottom wall portion of the tundish. The dam-like portion extending upward is formed over the entire length in the passage direction.

  The tundish for continuous casting of the present invention (the third invention according to claim 3) is the first invention, wherein the partition portion includes a lower weir portion extending upward from a bottom wall portion of the tundish, The molten steel circulation part is a molten metal hole formed in a penetrating manner in the thickness direction of the lower weir part at least in the vicinity of the bottom wall of the tundish, and comprises a molten metal hole connected to the upstream end of the molten steel passage part. It is said.

  According to 1st invention, the molten steel channel | path part extended toward the outer side of the longitudinal direction of the said molten steel distribution chamber from the arrangement | sequence row | line | column which consists of these inlets from the vicinity of a molten steel distribution | circulation part, and this molten steel Since it has a concave molten steel pool portion that surrounds the injection port with respect to at least the outer injection port of the plurality of injection ports, the molten steel flowing into the molten steel distribution chamber from the molten steel distribution portion The molten steel can be preferentially and intensively flowed to the inlet at the end of the molten steel distribution chamber, and at this time, the molten steel can be temporarily retained in the molten steel pool.

  Therefore, by flowing the molten steel through the molten steel passage portion, the contact area between the molten steel and the refractory can be reduced and the flow velocity of the molten steel can be increased as compared with the case where the bottom surface of the molten steel distribution chamber flows in a divergent shape. Therefore, the temperature drop of the molten steel flowing to the inlet at the end can be suppressed as much as possible. Further, by retaining a certain amount of molten steel in the molten steel reservoir, it is possible to prevent the molten steel temperature from decreasing near the inlet and maintain the molten steel temperature. Thereafter, the molten steel overflows from the molten steel pool and flows from the end portion toward the central portion at a stretch, so that the difference between the molten steel temperature at the end portion inlet and the molten steel temperature at the center portion inlet can be minimized. .

  According to the second invention, the wall portion on the inlet side of the molten steel passage portion is formed with a weir-like portion extending upward from the bottom wall portion of the tundish over the entire length in the passage direction. After a certain amount of time has passed since the molten steel was supplied to the tundish while ensuring the depth of the molten steel passage, and after the molten steel has been filled to some extent in the molten steel distribution chamber, the molten steel flows over the weir-shaped portion, and the molten steel is distributed. Molten steel can be supplied smoothly into the room.

  According to the third invention, the molten steel circulation part is a molten metal hole formed in a penetrating shape in the thickness direction of the lower weir part at least in the vicinity of the bottom wall part of the tundish, and continues to the upstream end of the molten steel passage part. Since it consists of a molten metal hole, immediately after the molten steel supply is started, the molten steel can be surely flowed into the molten steel passage portion by restricting the flow rate of the molten steel flowing into the molten steel distribution chamber.

It is a conceptual diagram of the continuous casting apparatus provided with the tundish for continuous casting of this invention. It is a top view of the tundish for continuous casting. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. It is a fragmentary perspective view of the tundish for continuous casting. It is a diagram which shows the molten steel temperature characteristic of the inlet located in the center part of a molten steel distribution chamber, and the inlet located in a terminal part. It is a diagram which shows the molten steel temperature characteristic of the inlet located in the center part of the molten steel distribution chamber in a prior art example, and the inlet located in a terminal part. It is a fragmentary perspective view of the tundish for continuous casting concerning another modification form. It is a top view of the tundish for continuous casting of a prior art example.

  Hereinafter, the continuous casting tundish 10 according to the embodiment of the present invention will be described with reference to the drawings as appropriate. First, the overall structure of the continuous casting apparatus 1 for steel including the continuous casting tundish 10 of the present invention. A brief explanation will be given.

  As shown in FIG. 1, a continuous casting apparatus 1 includes a ladle 3 that conveys molten steel 2 that has been produced from an electric furnace or the like, and a tundish 10 for continuous casting that is an intermediate container that temporarily stores the molten steel 2 ( Hereinafter referred to as a tundish 10), a mold 6 that casts the molten steel 2 to form a slab 7, a cooling zone 8 that cools the slab 7 that has come out of the mold 6, and a plurality of slabs that are transported while being supported. The support roll 9 is provided.

  In the continuous casting apparatus 1, the molten steel 2 conveyed by the ladle 3 is supplied to the tundish 10 through the injection nozzle 4 and the like, and the supplied molten steel 2 is temporarily stored in the tundish 10. Later, the plurality of molds 6 are supplied through the immersion nozzle 5. In each mold 6, the injected molten steel 2 is gradually cooled and becomes a slab 7 in which the surface portion of the molten steel 2 is solidified, and is drawn downward from the mold 6. The slab 7 drawn out from the lower part of the mold 6 is cooled in the cooling zone 8 and conveyed toward the downstream side while being supported by a plurality of support rolls 9.

  Next, the structure of the tundish 10 of the present invention will be described in detail. For convenience, in the following description, in the tundish 10 in plan view shown in FIG. 2, the upper side is the rear side, the lower side is the front side, and the left side is the left side. The right side will be described as the right side.

  As shown in FIGS. 2 to 5, the basic structure of the tundish 10 related to the present invention is connected to the molten steel receiving chamber 11 to which the molten steel is supplied from the ladle 3, and the molten steel receiving chamber 11. A molten steel distribution chamber 12 that supplies molten steel supplied to the molten steel receiving chamber 11 to the mold 6 and a partition 13 that partially partitions the molten steel distribution chamber 12 and the molten steel receiving chamber 11 are provided. And is configured in a T shape in plan view.

  Specifically, as shown in FIG. 2, the tundish 10 includes a T-shaped bottom wall portion 14 in a plan view, a front end wall portion 15 extending perpendicularly from the front end portion of the bottom wall portion 14, and the front end wall. A pair of left and right front side wall portions 16a and 16b extending rearward from both left and right end portions of the portion 15 and extending vertically from both left and right end portions of the bottom wall portion 14, and a rear end portion of the pair of left and right front side wall portions 16a and 16b A pair of left and right intermediate wall portions 17a and 17b extending inward in the left-right direction and extending perpendicularly from the front-rear direction middle portion of the bottom wall portion 14, and left and right inner ends of the pair of left and right intermediate wall portions 17a and 17b A pair of left and right rear side wall portions 18a and 18b extending rearward from the bottom wall portion 14 and extending vertically from a middle portion in the left and right direction of the bottom wall portion 14, and inward in the left and right direction from the rear end portions of the pair of left and right rear wall portions 18a and 18b And a rear end wall portion 19 extending vertically from the rear end portion of the bottom wall portion 14. It is constructed from. In addition, although illustration is abbreviate | omitted, you may provide the top-plate part which covers the inside of the tundish 10 from upper direction.

  Molten steel hot water receiving chamber 11 is a hot water receiving chamber from which molten steel is supplied from above through ladle 3 through pouring nozzle 4 and the like, and includes a rear portion of bottom wall portion 14 and a pair of left and right rear wall portions 18a, 18b, the rear end wall part 19, and the partition part 13 mentioned later are comprised by the trapezoid shape by planar view. That is, the pair of left and right rear side wall portions 18a and 18b are configured such that the wall portions gradually approach toward the rear in plan view. Further, the bottom surface of the molten steel receiving chamber 11 (the bottom surface in the rear portion of the bottom wall portion 14) is formed in a downwardly inclined shape that is gently inclined forward (see FIG. 4).

  The molten steel distribution chamber 12 is a distribution chamber that distributes molten steel according to the number of the injection ports 21a to 21c and supplies the molten steel to the plurality of molds 6 below through the immersion nozzle 5 and the like. The front end wall portion 15, the pair of left and right front side wall portions 16 a and 16 b, the pair of left and right intermediate wall portions 17 a and 17 b, and the partition portion 13 described later are configured in a horizontally long rectangular shape in plan view. Has been. A plurality of (three) injection ports 21 a to 21 c are formed in the bottom wall portion 14 of the molten steel distribution chamber 12 at predetermined intervals (equal intervals) in the longitudinal direction. The bottom surface of the molten steel distribution chamber 12 (the bottom surface of the front side portion of the bottom wall portion 14) is formed in a shape having unevenness in the left-right direction. The details will be described later, but a plurality of injection ports 21a to 21c are formed individually in the recesses. Has been.

  The plurality of inlets 21a to 21c are composed of a first inlet 21a, a second inlet 21b, and a third inlet 21c from the left to the right, and connect the centers of the first to third inlets 21a to 21c. The center line (arrangement row of the plurality of inlets 21) is straight in the left-right direction. The first inlet 21a is located at substantially the same distance from the front end wall 15, the left front side wall 16a, and the left intermediate wall 17a, and the third inlet 21c is also in front of the front end wall 15 and the right front. It is located at substantially the same distance from the side wall 16b and the right intermediate wall 17b. The molten steel injected into the mold 6 from the first inlet 21a becomes the first strand slab 7, and the molten steel injected into the mold 6 from the second inlet 21b becomes the second strand slab 7, The molten steel poured into the mold 6 from the injection port 21 c becomes the third strand slab 7.

  The partition portion 13 has a function of temporarily blocking the molten steel flowing into the molten steel distribution chamber 12 from the molten steel receiving chamber 11 and floating the inclusions, and extends vertically from the central portion of the bottom wall portion 14 slightly behind. The support section 22 includes a pair of left and right upper weir sections 23a and 23b and a pair of left and right lower weir sections 24a and 24b provided on the left and right sides of the support section 22. The support column 22 has a trapezoidal shape in a front view and a prismatic shape with a cross-sectional area decreasing toward the top. The height of the column portion 22 is set to be approximately the same as the height of the pair of left and right rear side wall portions 18a and 18b.

  The left and right pair of upper weir portions 23a and 23b each have a horizontally long flat plate shape and extend downward from the upper end portion of the tundish 10 so as to extend downward from the column portion 22 and the left and right pair of rear side wall portions 18a. , 18b are installed in a vertical orientation. Between each upper dam part 23a, 23b and the bottom wall part 14, the upstream opening which accept | permits the distribution | circulation of the molten steel which goes to the molten steel distribution chamber 12 from the molten steel receiving chamber 11 is formed. A pair of left and right lower dam portions 24a and 24b are disposed downstream of the pair of left and right upper dam portions 23a and 23b.

  The pair of left and right lower weir portions 24a and 24b each have a horizontally long flat plate shape and extend upward from the bottom wall portion 14 of the tundish 10 so as to extend upward from the bottom wall portion 14 of the tundish 10. It is installed in a vertical orientation between the parts 18a and 18b. Downstream openings that allow the flow of molten steel from the molten steel receiving chamber 11 to the molten steel distribution chamber 12 through the upstream opening are formed above the lower weir portions 24a and 24b.

  In the vicinity of the bottom wall portion 14 of each of the lower weir portions 24a and 24b, square-shaped hot water holes 25a and 25b are formed in a penetrating manner in the thickness direction in a front view. The molten metal holes 25a and 25b flow from the upstream opening and allow a part of the molten steel blocked by the lower weir portions 24a and 24b to flow to the molten steel distribution chamber 12. The lower end of the inner periphery of each hot water hole 25a, 25b is located on the same plane as the lower end of the bottom surface of the molten steel hot water receiving chamber 11. The molten metal holes 25a and 25b correspond to a molten steel distribution section that is provided in the partition section 13 and allows a part of molten steel to flow from the molten steel receiving chamber 11 to the molten steel distribution chamber 12.

Next, the molten steel passage portions 26a and 26b related to the present invention will be described.
As shown in FIGS. 2, 4, and 5, the bottom wall portion 14 of the molten steel distribution chamber 12 has an arrangement row including a plurality of inlets 21 a to 21 c from the vicinity of the molten metal holes 25 a and 25 b (molten steel circulation portion). A pair of left and right molten steel passage portions 26a and 26b extending from the molten steel receiving chamber 11 side toward the outside in the longitudinal direction of the molten steel distribution chamber 12 are formed. The pair of left and right molten steel passages 26a and 26b is directed toward the first and third inlets 21a and 21c at the outermost end by avoiding the second inlet 21b at the center of the molten steel immediately after the start of molten steel supply. In order to flow, the molten steel distribution chamber 12 is formed in a symmetrical C-shape with the column portion 22 sandwiched between the bottom wall portion 14 of the molten steel distribution chamber 12.

  Each molten steel passage portion 26a, 26b is formed in a shallow groove shape, and the bottom surface of each molten steel passage portion 26a, 26b is set lower than the lower end of the inner periphery of the molten metal holes 25a, 25b. The passage width at the upstream end of each molten steel passage portion 26a, 26b is set to be substantially the same as the lateral width of the upper dam portions 23a, 23b and the lower dam portions 24a, 24b. The passage width of the upstream passage portion of each molten steel passage portion 26a, 26b becomes narrower toward the front and downstream, and the middle portion of each molten steel passage portion 26a, 26b converts the flow of molten steel to the outside by about 90 degrees. The downstream passage portions of the molten steel passage portions 26a and 26b are formed to extend linearly in the left-right direction. The passage width at the downstream end of each of the molten steel passage portions 26a and 26b is set to a length that is about ½ or less of the upstream passage width.

  Weir-like portions 27a and 27b are formed in the passage wall portion on the front side of each molten steel passage portion 26a and 26b, extending upward from the bottom wall portion 14 and extending over the entire length in the molten steel flow direction. Each weir-like part 27a, 27b is formed in a dogleg shape in plan view, and its height is set lower than the upper end of the inner periphery of the hot water holes 25a, 25b. By forming these weir-shaped portions 27a and 27b, the depth of the molten steel passage portions 26a and 26b can be secured. The thickness of each dam-like part 27a, 27b is comparable to the thickness of the upper dam parts 23a, 23b and the lower dam parts 24a, 24b.

Next, the molten steel pool parts 28a-28c relevant to this invention are demonstrated.
As shown in FIGS. 2, 3, and 5, the front portion of the bottom wall portion 14 of the molten steel distribution chamber 12 and the bottom surface of the molten steel distribution chamber 12 surround each of the plurality of inlets 21 a to 21 c. A plurality of shallow concave pools 28a to 28c are formed. The plurality of molten steel reservoirs 28a to 28c are composed of a first molten steel reservoir 28a, a second molten steel reservoir 28b, and a third molten steel reservoir 28c from the left to the right. The second molten steel reservoir 28b on the center side of the molten steel distribution chamber 12 is formed in a longitudinally long rectangular shape in plan view. The second molten steel pool portion 28b is surrounded by a convex bottom portion 29 having a thickness upward. The upper surface of the convex bottom portion 29 is located on the same plane as the lower end of the bottom surface of the molten steel receiving chamber 11.

  The first and third molten steel pool portions 28a and 28c on both sides of the molten steel distribution chamber 12 are formed in a horizontally elongated rectangular shape in plan view. That is, the first and third molten steel reservoirs 28 a and 28 c on both sides are formed over substantially the entire left and right side portions of the bottom surface of the molten steel distribution chamber 12. The downstream ends of the pair of left and right molten steel passage portions 26a and 26b are communicated with the first and third molten steel reservoir portions 28a and 28c surrounding the outermost inlet ports 21a and 21c among the plurality of inlet ports 21a to 21c. ing. The bottom surfaces of the first and third molten steel pool portions 28a and 28c are located on the same plane as the bottom surfaces of the molten steel passage portions 26a and 26b.

Next, the flow of molten steel at the start of molten steel supply from the ladle 3 will be described.
The molten steel poured into the molten steel receiving chamber 11 from the ladle 3 through the injection nozzle 4 flows forward on the downward inclined bottom surface of the molten steel receiving chamber 11 and is a lower weir portion 24a which is a partition portion 13. 24b and the strut portion 22 are temporarily dammed up, but a part of the dammed molten steel passes through the molten metal holes 25a and 25b formed in the lower dam portions 24a and 24b. 12 flows into the upstream ends of the molten steel passage portions 26a and 26b.

  Next, the molten steel that has flowed into the molten steel passage portions 26a, 26b flows outward in the left-right direction to the downstream end without overflowing the molten steel passage portions 26a, 26b, and the outer first and third molten steel pool portions 28a, The gas flows into 28c intensively, fills the first and third molten steel reservoirs 28a and 28c, and fills the first and third inlets 21a and 21c.

  Then, when a predetermined time has elapsed from the start of supply of molten steel to the molten steel receiving chamber 11, the molten steel overflows from the first and third molten steel reservoirs 28 a, 28 c, and the overflowed molten steel is on the center side of the molten steel distribution chamber 12. The upper surface of the convex bottom portion 29 flows toward the top, flows into the second molten steel pool portion 28b, fills the second molten steel pool portion 28b, and fills the second inlet 21b.

  The molten steel that has flowed in from the molten metal holes 25a, 25b and the molten steel that has passed over the lower weir portions 24a, 24b after a short period of time or substantially at the same time after the molten steel overflows from the first and third molten steel reservoirs 28a, 28c. The second molten steel on the center side does not flow only through the molten steel passage portions 26a and 26b, and flows from the molten steel passage portions 26a and 26b over the dam-like portions 27a and 27b toward the center side of the molten steel distribution chamber 12. The molten steel flows into the reservoir portion 28b in a short period of time after the molten steel overflows from the first and third molten steel reservoir portions 28a, 28c.

  As described above, in the molten steel distribution chamber 12, the molten steel is retained in the outer first and third molten steel reservoirs 28a and 28c for a certain period of time, so that the molten steel temperature in the vicinity of the first and third inlets 21a and 21c is increased. The bottom wall during which the molten steel flows from the first and third inlets 21a and 21c to the second inlet 21b by maintaining the high temperature and then flowing the molten steel all at once toward the second molten steel pool portion 28b on the center side. Heat removal by the portion 14 is prevented as much as possible, and variations in molten steel temperature between the first and third inlets 21a, 21c and the second inlet 21b are reduced as much as possible.

  The flow of the molten steel described above will be described based on the molten steel temperature distribution between the strands. This molten steel temperature distribution is based on the actual temperature measurement results. The molten steel injection temperature was 1597 ° C. when the result of FIG. 6 was measured, and 1609 ° C. when the result of FIG. 7 was measured. The molten steel temperature was measured at the first inlet 21a (first strand (1st)) and the second inlet 21b (second strand (2st)) with a temperature measuring probe. Here, FIG. 6 shows the results of experiments using the tundish 10 of the present invention described above, and FIG. 7 shows, for comparison, molten steel passage portions 26a and 26b, molten steel as shown in FIG. The result of having experimented using the conventional tundish which is not provided with the reservoir parts 28a and 28c is shown.

  As shown in FIG. 6, in the tundish 10 of the present invention, the molten steel that has flowed into the molten steel distribution chamber 12 passes through the molten steel passage portions 26a and 26b, and the outer first and third molten steel pool portions 28a and 28c. After filling the first and third inlets 21a and 21c (first and third strands), it flows at once toward the second inlet 21b (second strand) on the center side. It was confirmed that the molten steel temperature hardly decreased during the movement of the molten steel, and the molten steel temperature difference between the strands was as small as about 10 ° C.

  Moreover, since the flow velocity of the molten steel flowing through the molten steel passage portions 26a and 26b is configured so that the passage width becomes narrower toward the downstream side, the flow velocity is higher than that when the bottom surface of the molten steel distribution chamber 12 flows in a divergent shape. Become. As a result, the molten steel immediately accumulates in the first and third molten steel reservoirs 28a and 28c, and then flows into the second molten steel reservoir 28b all at once, and the molten steel flows into the molten steel distribution chamber 12 through the molten metal hole 25a. Then, since the high heat of the molten steel propagates through the air to the vicinity of the second inlet 21b, and the molten steel flows into the second inlet 21b with almost no passage of time, as shown in FIG. There is almost no time difference between the inlets 21a and 21b (between the strands). According to the actual machine-side temperature result, the molten steel temperature in the vicinity of the second inlet 21b is slightly faster than the molten steel in the vicinity of the first inlet 21a, although the molten steel is preferentially flowed to the outside. It was.

  On the other hand, in FIG. 7 which is a result of using a conventional tundish, the molten steel flowing into the molten steel distribution chamber 12 is filled with the second inlet 21b (second strand) and then the outer first and third inlets. Since the bottom surface of the molten steel distribution chamber 12 flows toward the ends 21a and 21c (first and third strands), the molten steel temperature difference between the strands may increase to about 25 ° C. due to heat removal by the bottom wall portion 14. It could be confirmed.

  Further, the order of the inlets for filling the molten steel is not particularly controlled, and the flow rate of the molten steel is lowered because the bottom surface of the molten steel distribution chamber 12 flows in a divergent shape. A time difference of about 15 seconds occurs between the strands, and the temperature of the molten steel flowing through the injection ports 21a and 21c is lower than the temperature of the molten steel flowing through the injection port 21b. .

  In addition, in the explanation of the molten steel temperature distribution, matters not explicitly disclosed, for example, operating conditions and operating conditions, component size, weight, volume, various parameters, etc., are those normally practiced by those skilled in the art. In this case, matters that can be easily assumed by those skilled in the art are employed.

  As described above, in the tundish 10 of the present invention, the molten steel receiving chamber 11 side is located closer to the molten steel distribution chamber 12 than the arrangement row including the plurality of inlets 21a to 21c from the vicinity of the molten steel circulation portion (the molten metal holes 25a and 25b). The molten steel passage portions 26a and 26b extending outward in the longitudinal direction of the first and second concave first and second portions that are continuous with the molten steel passage portions 26a and 26b and surround the outer injection ports 21a and 21c among the plurality of injection ports 21a to 21c. Since the third molten steel pool portions 28a and 28c are provided, the molten steel flowing into the molten steel distribution chamber 12 from the molten steel distribution portion (molten holes 25a and 25b) is supplied to the molten steel distribution chamber 12 via the molten steel passage portions 26a and 26b. It is possible to flow preferentially and intensively to the inlets 21a and 21c at the end, and at this time, the molten steel can be temporarily retained in the first and third molten steel pools 28a and 28c.

  Therefore, by flowing the molten steel through the molten steel passage portions 26a and 26b, the contact area between the molten steel and the refractory can be reduced as compared with the case where the bottom surface of the molten steel distribution chamber 12 flows in a divergent shape. The flow rate can be increased, and therefore the temperature drop of the molten steel flowing to the inlets 21a and 21c at the end can be suppressed as much as possible. Further, by retaining a certain amount of molten steel in the first and third molten steel reservoirs 28a and 28c, it is possible to prevent the molten steel temperature from decreasing near the inlets 21a and 21c, and to maintain the molten steel temperature. Thereafter, the molten steel overflows from the first and third molten steel pools 28a and 28c and flows from the terminal part toward the central part at a stretch. Therefore, the molten steel temperature at the terminal inlets 21a and 21c and the central inlet 21b. The difference in molten steel temperature can be minimized.

  In addition, weir-like portions 27a and 27b extending upward from the bottom wall portion 14 of the tundish 10 are provided on the wall portions of the molten steel passage portions 26a and 26b on the inlets 21a to 21c side over the entire length in the passage direction. Since the molten steel passage portions 26a and 26b are secured, the molten steel is supplied to the tundish 10 and a predetermined time (for example, about 1 to 2 minutes) elapses. After being filled to some extent, the molten steel flows over the weirs 27a and 27b, and the molten steel can be smoothly supplied into the molten steel distribution chamber 12.

  Further, the molten steel circulation part is a hot water hole 25a, 25b formed in the thickness direction of the lower weir parts 24a, 24b in the vicinity of the bottom wall part 14 of the tundish 10, and is an upstream end of the molten steel passage parts 26a, 26b. Therefore, immediately after the molten steel supply is started, the molten steel can be surely flowed into the molten steel passage portions 26a and 26b by reducing the flow rate of the molten steel flowing into the molten steel distribution chamber 12.

Next, an embodiment in which the above embodiment is partially changed will be described.
[1] Although the tundish 10 of the above embodiment has a structure corresponding to three strands, it is not particularly limited to this number, and may correspond to three or more strands. That is, after the molten steel flowing into the molten steel distribution chamber 12 flows preferentially and intensively to the outermost injection port via the molten steel passage portions 26a and 26b, the molten steel is temporarily retained in the outer molten steel pool portion. It is not necessary to limit the number of inner strands because of the structure of flowing toward the injection port on the center side.

[2] The shape of the molten steel passage portions 26a and 26b of the above embodiment is not particularly limited to the shape as described above, and the molten steel that has flowed out of the molten steel distribution portion (the molten metal holes 25a and 25b) immediately after the molten steel supply is started. The shape of the molten steel passage portions 26a, 26b can be changed as appropriate as long as the shape of the molten steel passage portions 26a, 28c flows preferentially to the first and third molten steel pool portions 28a, 28c.

[3] The molten steel distribution part of the above embodiment is composed of the hot water holes 25a, 25b formed in the lower dam parts 24a, 24b in a square shape in front view, but is not particularly limited to this. As shown, it may consist of a molten metal hole 25Aa formed in a semicircular shape when viewed from the front. Moreover, although illustration is abbreviate | omitted, it may consist of a circular shaped hot water hole and the opening formed in the shape of a vertically long or horizontally long slit in front view, and the shape and structure of a molten steel distribution | circulation part can be changed suitably. In addition, although the lower end of the inner periphery of the molten metal hole 25Aa shown in FIG. 8 is located on the same plane as the lower end of the bottom surface of the molten steel passage portion 26a, there is no need to particularly limit it.

[4] In the above-described embodiment, the molten steel reservoir portions 28a to 28c are formed in all of the injection ports 21a to 21c, but the molten steel reservoir portion of the present invention is at least an outer side of the plurality of injection ports 21a to 21c. It suffices if it is formed so as to surround the inlets 21a and 21c, and the second molten steel reservoir 28b at the center is not necessarily required, and the second inlet 21b is directly formed in the convex bottom 29. There may be.

[5] In addition, those skilled in the art can implement the present invention by adding various modifications without departing from the spirit of the present invention, and the present invention includes such modifications. It is.

DESCRIPTION OF SYMBOLS 10 Tundish for continuous casting 11 Molten steel receiving chamber 12 Molten steel distribution chamber 13 Partition parts 21a-21c Inlet 24a, 24b Lower dam part 25a, 25b Molten hole (molten steel distribution | circulation part)
26a, 26b Molten steel passage part 27a, 27b Weir-shaped part 28a-28c Molten steel pool part

Claims (3)

A molten steel receiving chamber to which molten steel is supplied from a ladle, a molten steel distribution chamber for supplying molten steel supplied to the molten steel receiving chamber to a plurality of molds, and a space between the molten steel distributing chamber and the molten steel receiving chamber. In the continuous casting tundish provided with a partitioning part,
The molten steel distribution chamber has a plurality of inlets formed at predetermined intervals in the longitudinal direction,
The molten steel flow part provided in the partition part and capable of flowing a part of the molten steel from the molten steel receiving chamber to the molten steel distribution chamber, and the arrangement row comprising the plurality of inlets from the vicinity of the molten steel flow part A molten steel passage portion extending toward the outside in the longitudinal direction of the molten steel distribution chamber on the molten steel receiving chamber side, and a concave shape surrounding the injection port with respect to the molten steel passage portion and at least the outer injection port among the plurality of injection ports A continuous casting tundish characterized by comprising a molten steel reservoir.   2. The wall portion on the inlet side of the molten steel passage portion is formed with a weir-like portion extending upward from the bottom wall portion of the tundish over the entire length in the passage direction. The tundish for continuous casting as described. The partition portion includes a lower weir portion extending upward from the bottom wall portion of the tundish,
The molten steel flow part is a molten metal hole formed in a penetrating shape in the thickness direction of the lower weir part at least in the vicinity of the bottom wall of the tundish, and comprises a molten metal hole connected to the upstream end of the molten steel passage part. The tundish for continuous casting according to claim 1 or 2, characterized by the above.

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