WO2010119680A1

WO2010119680A1 - Continuous casting facility

Info

Publication number: WO2010119680A1
Application number: PCT/JP2010/002718
Authority: WO
Inventors: 今井俊太郎; 黒木雅嗣; 岡洋介
Original assignee: 新日本製鐵株式会社
Priority date: 2009-04-14
Filing date: 2010-04-14
Publication date: 2010-10-21
Also published as: BRPI1015033A2; CN102387878A; JPWO2010119680A1; CN102387878B; JP4880089B2; BRPI1015033B1

Abstract

Disclosed is a continuous casting facility equipped with a plurality of supporting rollers arranged oppositely on the opposite sides of the passage of cast piece, wherein each supporting roller has a plurality of split rollers arranged along the width direction of the cast piece, and for each supporting roller arranged at a position on the passage where the central solid-phase rate of the cast piece is 0.2-1.0 during continuous casting process, the interval A and the distance B satisfy the following relations; A≤0.001×B²-1.5×B+735 and 400≤B<680, when the interval of the split rollers adjoining in the width direction of the cast piece in the supporting rollers is defined as the interval A (mm), and the distance from a supporting roller adjacent to the above-mentioned supporting roller on the downstream side in the casting direction to a supporting roller adjacent to the above-mentioned supporting roller on the upstream side in the casting direction is defined as the distance B (mm).

Description

Continuous casting equipment

The present invention relates to a continuous casting facility provided with a plurality of support rolls arranged to face each other across a slab passage.
This application claims priority based on Japanese Patent Application No. 2009-097681 filed in Japan on April 14, 2009, the contents of which are incorporated herein by reference.

A continuous casting facility for producing a slab from molten metal is provided with a slab passage for passing a slab drawn from a tundish through a mold, a pair of rolls arranged opposite to each other across the slab passage, and the like. . In the roll group, a plurality of support rolls for guiding the slab are arranged side by side in the casting direction of the slab. Each support roll is rotatably provided with a central axis extending in the width direction of the slab as a rotation center axis, and the slab is supported in a state in which the slab is sandwiched by these support rolls while the slab is supported in a predetermined casting direction. Pull out to transport. Each support roll rotates with the movement of the slab, whereby the slab is smoothly guided.

In this continuous casting facility, bulging due to static pressure of unsolidified molten steel may occur on the slab below the mold. In particular, since both ends of the support roll described above are supported by bearing portions, the bulging amount near the center in the width direction of the slab increases as the support roll bends near the center in the width direction of the slab. Therefore, conventionally, in order to reduce the amount of bulging, a support roll is used in which the support roll is divided into a plurality of divided rolls in the width direction of the slab, and these divided rolls are supported by an intermediate bearing portion (Patent Document). 1).

In order to suppress this bulging, the distance between the support rolls on the downstream side is set to the distance between the support rolls on the upstream side at a position where the solid fraction of the slab corresponds to 0.3 to 0.9 during continuous casting. It is also proposed to make it smaller (Patent Document 2).

Japanese Unexamined Patent Publication No. 2007-30012 Japanese Unexamined Patent Publication No. 2005-193265

However, as a result of investigations by the present inventors, it has been found that bulging may not be sufficiently suppressed only by dividing the support roll into a plurality of divided rolls. For example, an unsupported portion where the roll does not contact the slab exists between the split rolls adjacent to each other in the slab width direction in one support roll. It was found that even if the interval between the divided rolls was made constant, the bulging amount could or might not be suppressed at the non-supported portion, and sufficient bulging suppression was not always achieved. This bulging caused central segregation, which is an internal defect of the slab, and deteriorated the slab quality.

The present invention has been made in view of such a point, and an object thereof is to reduce the bulging amount of a slab and suppress the center segregation of the slab.

In order to achieve the above object, a continuous casting facility according to an aspect of the present invention is a continuous casting facility including a plurality of support rolls arranged to face each other across a passage of a slab, and each of the support rolls Has a plurality of divided rolls arranged along the width direction of the slab, and the center solid phase ratio of the slab during the continuous casting process is 0.2 or more and less than 1.0. For each of the support rolls arranged at the position: An interval between the divided rolls adjacent to each other in the width direction of the slab in the support roll is defined as an interval A (mm), and the downstream of the support roll in the casting direction. When the distance from the adjacent support roll on the side to the adjacent support roll on the upstream side in the casting direction of the support roll is defined as the distance B (mm), the distance A and the distance B are the following formulas (1) and (2) Meet.
A ≦ 0.001 × B ² −1.5 × B + 735 (1)
400 ≦ B <680 (2)

According to the present invention, the center segregation of the slab can be suppressed by reducing the bulging amount of the slab.

It is explanatory drawing which shows the outline of a structure of the continuous casting installation concerning this Embodiment. It is explanatory drawing which showed typically the structure of the roll segment apparatus seeing from the side. It is explanatory drawing which showed typically the structure of the roll segment apparatus seeing from the side. It is explanatory drawing which showed the planar arrangement | positioning of a division | segmentation roll. It is the graph which showed the relationship between an unsupported zone width and a bulging index. It is the graph which showed the relationship between unsupported belt length and unsupported belt width.

Hereinafter, embodiments of the present invention will be described. Drawing 1 is an explanatory view showing the outline of the composition of continuous casting equipment 1 concerning this embodiment.

As shown in FIG. 1, the continuous casting facility 1 includes a tundish 2 for storing molten steel, a nozzle 4 for injecting molten steel into the mold 3 from the bottom of the tundish 2, and a slab through which a slab H drawn from the mold 3 passes. A pair of

roll groups

6 and 7 are provided so as to face each other across the passage 5 and the slab passage 5.

A pair of

rolls

6 and 7, so as to guide the slab H in the casting direction D ₁ along the slab passage 5, movable side of the slab passage 5 (the so-called L side, hereinafter, "the inner peripheral Side ”) and a fixed surface side (so-called F surface side, hereinafter referred to as“ periphery side ”). The inner peripheral roll group 6 includes a plurality of support rolls 10 that guide the inner peripheral side of the slab H in the slab passage 5. Each supporting roll 10, the center axis thereof so as to face in the width direction of the slab H, are arranged in a row along the casting direction D _1. Further, the outer peripheral side roll group 7 has a plurality of support rolls 11 for guiding the outer peripheral side of the slab H in the slab passage 5. Each supporting roll 11 has its central axis so as to face in the width direction of the slab H, are arranged in a row along the casting direction D _1.

The

support rolls

10 and 11 are attached to a roll segment device 20 as shown in FIGS. The roll segment device 20 includes an inner peripheral frame 21 to which a plurality of inner peripheral support rolls 10 are attached, and an outer peripheral frame 22 to which a plurality of outer peripheral support rolls 11 are attached. A support member for supporting the inner peripheral side frame 21 and the outer peripheral side frame 22 between the inner peripheral side frame 21 and the outer peripheral side frame 22 and adjusting the distance between the

support rolls

10 and 11. 23 is provided. The support member 23 is provided with a hydraulic cylinder 24. For example, a cylinder rod or a cylindrical body is used as the support member 23. When using a cylindrical body, the structure which adjusts the length of the supporting member 23 by a screwing form is preferable. For example, a configuration in which the screw portion is divided into two parts, or a configuration in which the screw portion is disposed between the support member 23 and the outer frame 22 can be adopted.

Supporting roll 10 on the inner circumferential side, a plurality in the width direction _{D 2} of the slab H, for example, three

split rolls

30a, 30b, are divided into 30c. Each divided rolls 30 forms a substantially cylindrical shape, is inserted through the shaft 31 extending in the slab width direction D ₂ in its center. Each divided roll 30 and the shaft 31 may have a one-piece structure or a separate structure. The shaft 31 may be divided in the axial direction by the intermediate bearing portion 33. With this configuration, the split roll 30 can rotate around the shaft 31. End bearing portions 32 are provided at both ends of the shaft 31. Further, the shaft 31 between the split rolls 30 is provided with an intermediate bearing portion 33 (see FIG. 2). When the shaft 31 is divided in the axial direction by the intermediate bearing portion 33, two bearings are arranged in the intermediate bearing portion 33. The end bearing portion 32 and the intermediate bearing portion 33 are supported by the frame 21 on the inner peripheral side.

Here, the distance B (mm) between the support rolls adjacent to each other in the casting direction with respect to one support roll (that is, the next support roll downstream in the casting direction and the next support roll upstream in the casting direction) is In a plan view as shown in FIG. 4, it is defined as the distance of the center portion of each roll.

As a result of extensive studies by the inventors, it has been found that adjusting the spacing in the casting direction between the support rolls is not sufficient to sufficiently suppress the center segregation of the slab. On the other hand, in addition to the above adjustment, the center segregation is performed by adjusting the interval between the divided rolls adjacent to each other in the width direction of the slab in one support roll to an appropriate range corresponding to the interval in the casting direction between the support rolls. The suppression effect is significantly improved. That is, in order to sufficiently suppress the amount of bulging that causes center segregation, it is not sufficient to adjust the split roll arrangement one-dimensionally as in the past, and the support roll arrangement and the split roll are two-dimensionally adjusted. It turns out that the arrangement needs to be adjusted. Therefore, the support rolls adjacent to each other in the casting direction of the one support roll (as viewed from the one support roll described above) centered on the unsupported portion of the cast piece between the divided rolls adjacent to each other in the width direction of the cast piece. Deformation of a two-dimensional flat plate (slab) in a range over a support roll adjacent to the front in the casting direction, and a support roll adjacent to the rear in the casting direction as viewed from the one support roll; Was analyzed and the amount of bulging was evaluated. Then, from the relationship between the bulging amount and the center segregation, the above formula (1) was derived as a condition for sufficiently suppressing the center segregation.

Further, if the distance between the support rolls adjacent to one support roll is 680 mm or more, the amount of bulging becomes too large even if the above formula (1) is satisfied, and the center segregation cannot be sufficiently suppressed. I understood. Therefore, the upper limit value in the above formula (2) is set to 680 mm.
In addition, 400 mm which is the lower limit in the above formula (2) was determined as the minimum interval at which the support rolls can actually be installed in the continuous casting facility.

As described above, the support roll (divided roll) is arranged in the continuous casting equipment of the present invention so as to satisfy the above formulas (1) and (2). For this reason, the amount of bulging of a slab can be made small and the center segregation of this slab can fully be suppressed.

The central solid fraction can be defined as the solid fraction of the molten portion in the center of the slab thickness direction and in the slab width direction.
The central solid phase ratio can be determined by heat transfer / solidification calculation. As the heat transfer / solidification calculation, an enthalpy method, an equivalent specific heat method, or the like is widely known, and any method may be used. For simplicity, the following equation is widely known, and this equation may be used.
Central solid fraction = (liquidus temperature-melt temperature) / (liquidus temperature-solidus temperature)
Here, the melting part temperature means the temperature of the melting part in the center part in the slab thickness direction and in the slab width direction, and can be obtained by heat transfer / solidification calculation. For the liquidus temperature, refer to, for example, “Akane and Steel, Nippon Steel Association, Vol. 55, No. 3 (19690227) S85, Japan Iron and Steel Institute”. The temperature can be calculated with reference to, for example, “Hirai, Kanamaru, Mori; Gakken 19 Committee, Fifth Solidification Phenomenon Council Material, Solidification 46 (December 1968)”.

As shown in FIG. 4, the split rolls 30 are arranged in a so-called zigzag shape (catch stitch shape). That is, the gaps between the divided rolls are arranged in a zigzag so that they are not aligned in a line along the casting direction. And in the support roll 10a which exists in the position where the center solid phase rate of the slab H in the roll group 6 is 0.2 or more and less than 1.0 during continuous casting, the division | segmentation which comprises the support roll 10a An interval A between the rolls 30, that is, an interval A between the adjacent divided rolls 30 a and 30 b in the slab width direction D ₂ (hereinafter sometimes referred to as “non-support band width A”), and a casting direction D of the support roll 10 a. The distance (interval) B between the support rolls 10b and 10c on both sides of ₁ (hereinafter sometimes referred to as “non-supporting band length B”) satisfies the following expressions (1) and (2). Is set to Detailed description of these formulas (1) and (2) will be described later. Note that the minimum value of the non-supporting band width A is, for example, about 100 mm as a value at which the split roll 30 can be actually installed.
A ≦ 0.001 × B ² −1.5 × B + 735 (1)
400 ≦ B <680 (2)
However, A is divided rolls 30a adjacent to the slab width direction _{D 2} in the support rolls 10a, between 30b spacing (mm), B is the support roll 10b on both sides of the casting direction _{D 1} of the supporting

roller

10a, 10c The distance between them (mm).

As shown in FIGS. 2 and 3, the support roll 11 on the outer peripheral side also has a plurality of, for example, three divided

rolls

40 a, 40 _b , and 40 c in the width direction D ₂ of the slab H, like the support roll 10 on the inner peripheral side. It is divided into Each divided rolls 40 forms a substantially cylindrical shape, is inserted through the shaft 41 extending in the slab width direction D ₂ in its center. Each split roll 40 and shaft 41 may have a separate structure or a separate structure. The shaft 41 may be divided in the axial direction by the intermediate bearing portion 43. With this configuration, the split roll 40 can rotate around the shaft 41. End bearing portions 42 are provided at both ends of the shaft 41. An intermediate bearing 43 is provided on the shaft 41 between the split rolls 40. When the shaft 41 is divided in the axial direction by the intermediate bearing portion 43, two bearings are required for the intermediate bearing portion 43. The end bearing portion 42 and the intermediate bearing portion 43 are supported by the frame 22 on the outer peripheral side. The planar arrangement of the divided rolls 40 is the same as the planar arrangement of the inner circumferential divided rolls 30 described in FIG. That is, the support roll 11 and the division | segmentation roll 40 are arrange | positioned so that the said Formula (1) and Formula (2) may be satisfy | filled.

The operation of the continuous casting equipment 1 configured as described above will be described. First, molten steel stored in the tundish 2 is injected into the mold 3 through the nozzle 4. In the mold 3, the molten steel is cooled from the outer periphery and solidified to form a slab H. The slab H is drawn from the mold 3 to the slab passage 5 and is moved downstream along the casting direction D ₁ while being guided by the

roll groups

6 and 7. At this time, the distance between the support rolls 10 and 11 in the

roll groups

6 and 7 is adjusted by the roll segment device 20 so that the slab H has a predetermined thickness. The slab H is further cooled while passing through the slab passage 5 and solidifies to the inside.

Next, the above formulas (1) and (2) will be described. As a result of intensive studies, the inventors have adjusted the spacing between support rolls and also the spacing between adjacent divided rolls in one support roll in order to sufficiently suppress the center segregation of the slab. I found it necessary. That is, in order to sufficiently suppress the amount of bulging that causes center segregation, it has been found that the interval between the rolls needs to be adjusted two-dimensionally.

Therefore, as shown in FIG. 4, divided rolls 30a adjacent to the slab width direction _{D 2} the support roll 10a, around the unsupported portion of the slab H between 30b, both sides of the casting direction _{D 1} of the supporting roller 10a The deformation amount in the slab thickness direction (hereinafter referred to as “bulging amount”) of the two-dimensional flat plate (non-supporting band S) extending to the supporting

rolls

10b and 10c is analyzed using a finite element method, and the bulging amount is calculated. evaluated. Evaluation of the bulging amount was performed in the roll group 6 at a position where the central solid phase ratio of the slab H corresponds to 0.8. This central solid phase ratio is in the range of 0.2 or more and less than 1.0. This central solid fraction has been separately confirmed that when the central solid fraction of the slab H is 0.2 or more and less than 1.0, bulging of the slab H occurs and central segregation occurs. Therefore, it was set as the representative value. Further, in the non-supporting band S, the bulging amount was evaluated by changing the non-supporting band width A in a range of 400 mm or less and changing the non-supporting band length B in 450 mm, 560 mm, 600 mm, 640 mm, and 680 mm. .

The evaluation results of the bulging amount are shown in FIG. The horizontal axis of FIG. 5 indicates the non-supporting band width A. The vertical axis in FIG. 5 indicates the ratio of the bulging amount when the unsupported band width A is 0 mm and the unsupported band length B is 560 mm, and the bulging amount is defined as 1. is doing. The non-support band width A of 0 mm means a case where the support roll is not divided. Although the non-supporting band length B is 280 mm, for the sake of convenience, the non-supporting band length B is expressed as 560 mm even when the non-supporting band width A is 0 mm for comparison with the case where the support roll is divided. ing.
Further, when the non-supporting band width A is 0 mm and the supporting roll is not divided, there is a problem that bulging occurs due to the bending of the supporting roll as described above. However, here, when considering the case where the non-supporting band width A and the non-supporting band length B are changed, the case where the non-supporting band width A is 0 mm is used as a reference when the bulging amount is the smallest. In addition, it was assumed that the support roll could be operated without bending.
Here, the bulging amount when the non-supporting band width A is 0 mm and the non-supporting band length B is 560 mm is set as a standard when a non-divided support roll (A = 0 mm) is used. supporting roll distance casting direction D ₁ and is based on the fact of the order of 280 mm. Then, when the inventors investigated, it turned out that the center segregation of slab H can fully be suppressed as a bulging index is 2.8 or less. That is, it was found that the range below the thick dotted line in FIG. 5 is a range in which the center segregation can be suppressed.

Therefore, the relationship between the unsupported band width A and the unsupported band length B that satisfies the bulging index of 2.8 or less was obtained. That is, when the unsupported band length B was varied, the unsupported band width A at which the bulging index was 2.8 or less was determined. The unsupported band width A and the unsupported band length B in this range were plotted as shown in FIG. Then, the plot in FIG. 6 was approximated by a polynomial to derive the relational expression of the above formula (1).

Further, as shown in FIG. 5, in the case where the non-supporting band length B is 680 mm or more, even if the non-supporting band width A is reduced, the non-supporting band length B is too large, so that the center segregation is entirely observed. It turned out to be worse. Further, when the non-support band width A is 0 mm (that is, when a non-divided support roll is used), the bulging index is 2.0 or more (the range above the thin dotted line in FIG. 5), and the center segregation is sufficient. It was also found that it was not possible to suppress it. Therefore, in the above formula (2), the upper limit value of the unsupported belt length B is set to 680 mm. Incidentally, 400 mm which is the lower limit in the formula (2) is determined on the basis that the actual installed smallest possible spacing of the casting direction _{D 1} to the adjacent support rolls 10 and 11 in a continuous casting machine 1 is 200mm ing.

According to the above embodiment, the case where the center solid phase ratio of the slab H is 0.8 has been described, but a similar experiment was performed at a plurality of positions corresponding to 0.2 or more and less than 1.0. As a result, the same results as above were obtained.

As described above, according to the present invention, in the

roll groups

6 and 7 at positions where the central solid fraction of the slab H corresponds to 0.2 or more and less than 1.0, the support rolls 10 and 11 (split rolls) 30 and 40) are arranged so as to satisfy the above formulas (1) and (2), the bulging amount of the slab H passing through the slab passage 5 can be reduced. Therefore, the center segregation of the slab H can be sufficiently suppressed, and a high quality slab can be manufactured.

In addition, the apparatus of 1 aspect of this invention can also be described as follows: It is a continuous casting installation provided with two or more support rolls arrange | positioned on both sides of a slab channel | path, and the said support roll is width | variety of slab In a support roll at a position where the center solid phase ratio of the slab is equal to or greater than 0.2 and less than 1.0 during continuous casting, the slab is divided into a plurality of divided rolls in the direction. The interval A between the adjacent divided rolls and the interval B between the adjacent support rolls in the casting direction between the divided rolls adjacent in the slab width direction satisfy the above formula (1) and the above formula (2). Features.

The present invention is useful for a continuous casting facility provided with a plurality of support rolls arranged to face each other across a slab passage.

DESCRIPTION OF SYMBOLS 1 Continuous casting equipment 2 Tundish 3 Mold 4 Nozzle 5

Slab passage

6, 7

Roll group

10, 11 Support roll 20

Roll segment apparatus

21, 22 Frame 23 Support member 24 Hydraulic cylinder 30, 40

Split roll

31, 41

Shaft

32, 42

End bearing part

33, 43 Intermediate bearing part H Cast piece S Non-supporting band

Claims

A continuous casting facility provided with a plurality of support rolls arranged to face each other across the slab passage,
Each of the support rolls has a plurality of divided rolls arranged along the width direction of the slab,
About each said support roll arrange | positioned in the position on the said channel | path where the center solid phase rate of the said slab in a continuous casting process will be 0.2 or more and less than 1.0:
The interval between the divided rolls adjacent in the width direction of the slab in the support roll is defined as an interval A (mm),
When the distance from the next support roll on the downstream side in the casting direction of the support roll to the next support roll on the upstream side in the casting direction of the support roll is defined as a distance B (mm), the distance A and the distance B are
A ≦ 0.001 × B 2 −1.5 × B + 735 (1)
And 400 ≦ B <680 (2)
Continuous casting equipment characterized by satisfying