CN102387878B - Continuous Casting Equipment - Google Patents

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=0.001B2-1.5B+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

technical field

The present invention relates to a continuous casting facility including a plurality of back-up rolls arranged to face each other across a slab passage.

This application claims priority based on Japanese Patent Application No. 2009-097681 for which it applied in Japan on April 14, 2009, and uses the content here.

Background technique

A continuous casting facility for producing slabs from molten metal is provided with: a slab passage through which the slab drawn from the tundish through the mold passes; a pair of rollers arranged oppositely across the slab passage, etc. . In the roll set, a plurality of support rolls guiding the slab are arranged in line in the casting direction of the slab. The support rolls are provided so as to be rotatable about the central axis extending in the width direction of the slab as the center axis of rotation, and the slab is supported in a state of sandwiching the slab by these support rolls while the slab is held in a predetermined casting direction. Pull out in the direction to transport. The respective support rolls rotate along with the movement of the slab, whereby the slab is smoothly guided.

In this continuous casting facility, sometimes a slab bulges under the mold due to the static pressure of the unsolidified molten steel. In particular, since both ends of the back-up roll are supported by the bearings, the back-up roll bends near the center in the width direction of the slab, so the amount of swelling near the center in the width direction of the slab becomes large. Therefore, conventionally, in order to reduce the amount of bulging, a support roll divided into a plurality of divided rolls in the width direction of the slab has been used (Patent Document 1), and these divided rolls are supported by intermediate bearings.

In addition, in order to suppress the bulging, it has also been proposed (Patent Document 2) that in continuous casting, at a position where the solid fraction of the slab corresponds to 0.3 to 0.9, the spacing ratio between the backup rolls on the downstream side is adjusted to The space between the backup rolls on the upstream side is small.

prior art literature

patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 2007-30012

Patent Document 2: Japanese Patent Laid-Open No. 2005-193265

Contents of the invention

The technical problem to be solved by the invention

However, the inventors of the present invention have found that swelling cannot be sufficiently suppressed only by dividing the support roll into a plurality of divided rolls. For example, there are non-supported portions where the rolls and the cast slab do not contact between divided rolls adjacent to each other in the width direction of the slab among one support roll. Even if the distance between the divided rollers is constant, the amount of swelling may or may not be suppressed in the unsupported portion, and sufficient swelling suppression may not always be achieved. And, center segregation, which is an internal defect of the slab, occurs due to the bulging, and the quality of the slab deteriorates.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the amount of swelling of the cast slab and to suppress center segregation of the cast slab.

Means used to solve technical problems

In order to achieve the above objects, a continuous casting facility according to an aspect of the present invention is a continuous casting facility that includes a plurality of back-up rolls arranged to face each other across a passage of a cast slab, and each of the back-up rolls has a length arranged along the width direction of the slab. A plurality of split rolls, and each of the support rolls arranged at a position on the passage where the central solid phase ratio of the cast slab in the continuous casting process is 0.2 or more and less than 1.0: The interval between the above-mentioned split rolls adjacent in the above-mentioned width direction of the slab is defined as the interval A (mm), and the interval from the adjacent back-up roll on the downstream side of the above-mentioned back-up roll in the casting direction to the above-mentioned back-up roll on the casting direction upstream side is defined as the interval A (mm). When the distance to adjacent backup rolls is defined as distance B (mm), interval A and distance B satisfy the following formulas (1) and (2).

A≤0.001×B ² -1.5×B+735 …(1)

400≤B＜680 ...(2)

The effect of the invention:

According to the present invention, it is possible to reduce the amount of swelling of the slab and suppress the center segregation of the slab.

Description of drawings

FIG. 1 is an explanatory diagram showing an outline of the configuration of a continuous casting facility according to the present embodiment.

Fig. 2 is an explanatory diagram schematically showing the configuration of the roll section device viewed from the side.

Fig. 3 is an explanatory diagram schematically showing the configuration of the roll section device viewed from the side.

Fig. 4 is an explanatory diagram showing a planar arrangement of split rollers.

Fig. 5 is a graph showing the relationship between the unsupported band width and the swelling index.

FIG. 6 is a graph showing the relationship between the length of the unsupported band and the width of the unsupported band.

Detailed ways

Embodiments of the present invention will be described below. FIG. 1 is an explanatory diagram showing an outline of the configuration of a continuous casting facility 1 according to the present embodiment.

As shown in Figure 1, the continuous casting equipment 1 has: a tundish 2 for accumulating molten steel; a nozzle 4 for injecting molten steel into the mold 3 from the bottom of the tundish 2; The cast sheet H passes through; and a pair of roller sets 6 and 7 are disposed opposite to each other across the cast sheet passage 5 .

A pair of roller groups 6 and 7 are provided on the movable surface side (so-called L surface side, hereinafter sometimes referred to as "inner peripheral side") and fixed surface side (so-called F surface side, hereinafter sometimes described as "outer peripheral side") of the slab passage 5, respectively. side") in order to guide the slab H in the casting direction D ₁ along the slab passage 5. The roller group 6 on the inner peripheral side has a plurality of backup rollers 10 that guide the inner peripheral side of the slab H in the slab passage 5 . The support rolls 10 are arranged in a row along the casting direction _D1 so that their central axes face the width direction of the slab H. In addition, the roller group 7 on the outer peripheral side has a plurality of backup rollers 11 that guide the outer peripheral side of the slab H in the slab passage 5 . The support rolls 11 are arranged in a row along the casting direction _D1 so that their central axes face the width direction of the slab H.

As shown in FIGS. 2 and 3 , the backup rolls 10 and 11 are attached to a roll section device 20 . The roll section device 20 has an inner peripheral frame 21 on which a plurality of inner peripheral backup rolls 10 are attached, and an outer peripheral frame 22 on which a plurality of outer peripheral backup rolls 11 are attached. Between the frame 21 on the inner peripheral side and the frame 22 on the outer peripheral side, a support member 23 is provided for supporting the frame 21 on the inner peripheral side and the frame 22 on the outer peripheral side, and supports the support roller 10, 11 intervals to adjust. A hydraulic cylinder 24 is provided in the supporting member 23 . In addition, as the supporting member 23, for example, a piston rod or a cylinder is used. When a cylindrical body is used, it is preferable that the supporting member 23 is configured to adjust its length by screwing. For example, it is possible to employ a configuration in which the screwing portion is divided into two, or a configuration in which the screwing portion is arranged between the supporting member 23 and the frame 22 on the outer peripheral side.

The support roll 10 on the inner peripheral side is divided into a plurality of, for example, three divided rolls 30a, 30b, and 30c in the width direction _D2 of the slab H. Each split roll 30 has a substantially cylindrical shape, and a shaft 31 extending in the slab width direction _D2 is inserted through the center thereof. Each of the split rollers 30 and the shaft 31 may be an integral structure or may be an independent structure. In addition, the shaft 31 may be divided in the axial direction by the intermediate bearing portion 33 . With the above configuration, the split roller 30 is rotatable around the shaft 31 . End bearings 32 are provided at both ends of the shaft 31 . In addition, an intermediate bearing portion 33 is provided on the shaft 31 between the split rollers 30 (see FIG. 2 ). When the shaft 31 is divided in the axial direction by the intermediate bearing portion 33 , two bearings are arranged on the intermediate bearing portion 33 . These end bearing portions 32 and intermediate bearing portions 33 are supported by the frame 21 on the inner peripheral side.

Here, in a plan view as shown in FIG. 4 , with respect to one backup roll, two adjacent backup rolls in the casting direction (that is, adjacent backup rolls on the downstream side in the casting direction and adjacent backup rolls on the upstream side in the casting direction) The distance B (mm) between adjacent support rollers) is defined as the distance between the center portions of the respective rollers.

As a result of earnest research, the inventors have found that in order to sufficiently suppress center segregation of cast slabs, it is not sufficient to merely adjust the spacing between backup rolls in the casting direction. On the other hand, in addition to the above-mentioned adjustment, by adjusting the distance between the division rolls adjacent in the cast sheet width direction in one back-up roll to an appropriate range by corresponding to the space between the back-up rolls in the casting direction, by The suppression effect of this central segregation is remarkably improved. That is, it was found that in order to sufficiently suppress the amount of swelling that causes center segregation, it is not sufficient to only adjust the arrangement of the split rolls one-dimensionally as in the past, and it is necessary to adjust the arrangement of the backup rolls and the arrangement of the split rolls two-dimensionally. Therefore, in one support roll, centering on the unsupported portion of the slab between the adjacent split rolls in the width direction of the slab, two adjacent support rolls (from The back-up roll adjacent to the front of the casting direction viewed from the above-mentioned one back-up roll and the back-up roll adjacent to the rear of the casting direction viewed from the above-mentioned one back-up roll; hereinafter also simply described as two adjacent back-up rolls) range The deformation of the dimension plate (cast sheet) was analyzed, and the amount of swelling was evaluated. Furthermore, from the relationship between the swelling amount and the center segregation, the above formula (1) was derived as a condition for sufficiently suppressing the center segregation.

In addition, it was found that when the interval between two adjacent support rolls of one support roll is 680 mm or more, even in the case where the above-mentioned formula (1) is satisfied, the swelling amount becomes too large, and cannot sufficiently Suppresses central segregation. 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), is determined as the minimum interval at which backup rolls can actually be installed in the continuous casting facility.

As described above, in the continuous casting facility of the present invention, the backup rolls (segmented rolls) are arranged so as to satisfy the above formulas (1) and (2). Therefore, the amount of swelling of the slab can be reduced, and the center segregation of the slab can be sufficiently suppressed.

In addition, the central solid fraction can be defined as the solid fraction of the melted portion in the central portion in the thickness direction of the slab and in the width direction of the slab.

In addition, the central solid fraction can be obtained by heat transfer and solidification calculation, and heat transfer and solidification calculations are known such as the enthalpy method and the equivalent specific heat method, and any method may be used. In addition, the following formula is known briefly, and this formula can also be used.

Central solid phase ratio = (liquidus temperature - melting part temperature) / (liquidus temperature - solidus temperature)

Here, the melting portion temperature means the temperature of the melting portion in the central portion in the thickness direction of the slab and in the width direction of the slab, and can be obtained by heat transfer solidification calculation. In addition, the liquidus temperature can be calculated by referring to, for example, "Iron and Steel, Journal of the Japan Iron and Steel Association, Vol. 55, No. 3 (19690227) S85, Japan Iron and Steel Association"; "Heiju, Kanamaru, Mori; Gakatsu 19th Committee, The 5th Solidification Phenomenon Association Data, Solidification 46 (December 1968)" to calculate.

As shown in FIG. 4 , the split rollers 30 are arranged in a so-called zigzag shape (zigzag shape). That is, the gaps between the split rolls are arranged in a meandering manner so as to be misaligned in a row along the casting direction. In addition, in the continuous casting, among the backup rolls 10a at the position corresponding to the center solid phase ratio of the slab H of the roll group 6 at a position of 0.2 or more and less than 1.0, the interval between the divided rolls 30 constituting the backup roll 10a, that is, the The gap A between the adjacent split rolls 30a, 30b in the cast sheet width direction _D2 (hereinafter sometimes referred to as "unsupported belt width A"), and the two adjacent support rolls in the casting direction _D1 of the support roll 10a The distance (interval) B (hereinafter sometimes referred to as "unsupported belt length B") between the rollers 10b and 10c is set so as to satisfy the formulas (1) and (2) shown below. The detailed description of these formula (1) and formula (2) will be mentioned later. In addition, the minimum value of the unsupported tape width A is set to a value at which the split roller 30 can actually be installed, for example, about 100 mm.

A≤0.001×B ² -1.5×B+735 …(1)

400≤B＜680 ...(2)

Wherein, A is the interval (mm) between the division rolls 30a, 30b adjacent in the cast sheet width direction _D2 among the support rolls 10a, and B is the two adjacent support rolls in the casting direction _D1 of the support roll 10a. The interval (mm) between 10b and 10c.

As shown in FIG. 2 and FIG. 3 , the support roll 11 on the outer peripheral side is also divided into a plurality of, for example, three divided rolls 40a, 40b in the width direction _D2 of the cast sheet H, like the support roll 10 on the inner peripheral side. , 40c. Each split roll 40 is formed in a substantially cylindrical shape, and a shaft 41 extending in the slab width direction _D2 is inserted through the center thereof. Each of the split rollers 40 and the shaft 41 may have an integral structure or an independent structure. In addition, the shaft 41 may be divided in the axial direction by the intermediate bearing portion 43 . With the above configuration, the split roller 40 is rotatable around the shaft 41 . End bearings 42 are provided at both ends of the shaft 41 . In addition, an intermediate bearing portion 43 is provided on the shaft 41 between the split rollers 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 . These end bearing portions 42 and intermediate bearing portions 43 are supported by the frame 22 on the outer peripheral side. Note that the planar arrangement of the split rollers 40 is the same as the planar arrangement of the split rollers 30 on the inner peripheral side described in FIG. 4 , and therefore description thereof will be omitted. That is, the backup roll 11 and the split roll 40 are configured to satisfy the above formula (1) and formula (2).

The action of the continuous casting facility 1 configured as above will be described. First, the 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 and solidified from the outer periphery to form a slab H. The slab H is drawn from the mold 3 to the slab passage 5 , and moves downstream along the casting direction D ₁ while being guided by the roller sets 6 , 7 . At this time, the distance between the backup rolls 10 and 11 in the roll groups 6 and 7 is adjusted by the roll section device 20 so that the cast sheet H has a predetermined thickness. In addition, the slab H is further cooled and solidified inside while passing through the slab passage 5 .

Next, the above formula (1) and formula (2) will be described. As a result of earnest research, the inventors have found that in order to sufficiently suppress center segregation of cast slabs, it is necessary to adjust the interval between backup rolls and also to adjust the interval between adjacent split rolls in one backup roll. That is, it was found that in order to sufficiently suppress the amount of swelling that causes center segregation, it is necessary to two-dimensionally adjust the interval between the rollers.

Therefore, as shown in FIG. 4, in the support roll 10a, centering on the unsupported portion of the slab H between the split rolls 30a, 30b adjacent in the slab width direction _D2 , using the finite element method, the expanded The amount of deformation (hereinafter referred to as "bulging amount") in the thickness direction of the slab of the two-dimensional flat plate (unsupported belt S) to the two adjacent support rolls 10b and 10c in the casting direction _D1 of the support roll 10a is analyzed , and the amount of bulging was evaluated. The evaluation of the swelling amount was performed in the roll group 6 at the position where the center solid fraction of the slab H corresponds to 0.8. The center solid phase ratio is within the range of 0.2 to less than 1.0. In the range of the central solid fraction of the cast slab H from 0.2 to less than 1.0, it was also confirmed that the swell of the cast slab H occurred to cause central segregation, so the central solid fraction was set as a representative value. In addition, in the unsupported tape S, the unsupported tape width A was changed within a range of 400 mm or less, and the unsupported tape length B was changed to 450 mm, 560 mm, 600 mm, 640 mm, and 680 mm to evaluate the swelling amount.

Fig. 5 shows the evaluation results of the swelling amount. The horizontal axis in FIG. 5 represents the width A of the unsupported band. In addition, the vertical axis of FIG. 5 represents the ratio of the bulging amount when the unsupported zone width A is 0 mm and the unsupported zone length B is 560 mm is 1, and this is defined as a bulging index. In addition, the non-supported belt width A being 0 mm means that the support roll is not divided. The unsupported belt length B is 280 mm, but for comparison with the case where the backup roll is not divided, even when the unsupported belt width A is 0 mm, the unsupported belt length B is described as 560 mm for convenience.

In addition, when the unsupported belt width A is 0 mm and the support roll is not divided, there is actually a problem of swelling due to bending of the support roll as described above. However, here, in the case of changing the unsupported belt width A and the unsupported belt length B, in order to use the case where the unsupported belt width A is 0 mm as the benchmark for the case where the amount of swelling is the least, it is assumed that the support roll Operates without bending.

Here, the basis for taking the swelling amount when the unsupported belt width A is 0 mm and the unsupported belt length B is 560 mm is taken as a reference is that, when an undivided support roll (A=0 mm) is used, it is generally set The distance between the backup rolls in the casting direction _D1 is about 280mm. Therefore, the inventors found that the center segregation of the slab H can be sufficiently suppressed when the swell 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 center segregation can be suppressed.

Therefore, the relationship between the unsupported zone width A and the unsupported zone length B satisfying the condition that the swelling index is 2.8 or less was obtained. That is, when the unsupported zone length B is varied, the unsupported zone width A at which the inflation index becomes 2.8 or less is obtained, respectively. The unsupported zone width A and unsupported zone length B in this range are shown in graphs as shown in FIG. 6 . Then, polynomial approximation was performed on the diagram in FIG. 6 to derive the relational expression of the above-mentioned formula (1).

Furthermore, as shown in FIG. 5 , it can be seen that when the unsupported zone length B is 680 mm or more, even if the unsupported zone width A is reduced, the unsupported zone length B is too large, so that the center segregation deteriorates as a whole. In addition, it can also be seen that when the unsupported belt width A is 0 mm (that is, when an undivided support roll is used), when the inflation index is 2.0 or more (the range above the thin dotted line in FIG. 5 ), it is not possible to sufficiently Suppresses central segregation. Therefore, in the above formula (2), the upper limit of the length B of the unsupported zone is set to 680 mm. In addition, 400 mm, which is the lower limit value in the above formula (2), is determined based on the fact that in the continuous casting equipment 1, the minimum distance between the backup rolls 10 and 11 adjacent in the casting direction _D1 can be actually provided. is 200mm.

According to the above embodiment, the case where the central solid phase fraction of the slab H is 0.8 has been described. However, the results of similar experiments were carried out at a plurality of positions corresponding to 0.2 or more and less than 1.0, and the same results as above were obtained. the result of.

As described above, according to the present invention, the support rolls 10, 11 (divided rolls 30, 40) in the roll groups 6, 7 corresponding to the position where the central solid fraction of the slab H is 0.2 or more and less than 1.0 are Since it is arrange|positioned so that said formula (1) and formula (2) may be satisfied, the swelling amount of the slab H in the process of 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, an apparatus according to an aspect of the present invention can also be described as follows: a continuous casting facility including a plurality of back-up rolls arranged to face each other with a slab passage interposed therebetween, wherein the back-up rolls are positioned in the width direction of the slab The top is divided into a plurality of split rolls, and in continuous casting, among the support rolls corresponding to the position where the central solid phase ratio of the slab is 0.2 or more and less than 1.0, among the support rolls adjacent to the slab width direction The interval A between the split rolls and the interval B between two adjacent support rolls in the casting direction between the split rolls adjacent in the width direction of the slab satisfy the above formula (1) and the above formula (2) .

Industrial Applicability

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

Symbol Description

1 Continuous casting equipment

2 tundish

3 mold

4 nozzles

5 casting channel

6, 7 roller group

10, 11 support roller

20 roller section device

21, 22 frame

23 Support Parts

24 hydraulic cylinders

30, 40 split roller

31, 41 axis

32, 42 end bearings

33, 43 Intermediate bearing part

H casting

S unsupported band

Claims (1)

1. continuous casting equipment, possess the path of the slab of clipping and a plurality of support roller of arranged opposite is characterized in that,

Each above-mentioned support roller has along a plurality of rollers of cutting apart of the width configuration of above-mentioned slab,

About the center solid rate in the above-mentioned slab of continuous casting in operation, become more than 0.2 and be less than above-mentioned each support roller configured on the position on 1.0 above-mentioned path:

On the above-mentioned width in above-mentioned slab by above-mentioned support roller the above-mentioned interval of cutting apart between roller of adjacency be defined as interval A (mm),

Distance definition till will be from the adjacent support roller in the casting direction downstream of above-mentioned support roller to the adjacent support roller of the casting direction upstream side of above-mentioned support roller is during apart from B (mm),

Interval A and satisfied apart from B

A≤0.001 * B ²-1.5 * B+735 ... (1) and

400≤B＜680 …(2)。

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