[Document Type] Specification
[Title of the Invention] SECONDARY COOLING APPAI^TUS OF CONTINUOUS CASTING MACHINE AND SECONDARY COOLING METHOD [Technical Field of the Invention]
[0001]
The present invention relates to a secondary cooling apparatus of a continuous casting machine and a secondary cooling method.
Priority is claimed on Japanese Patent Application No. 2011-249762, filed on November 15, 2011, and the contents of which are incorporated herein by reference. [Related Art]
[0002]
In a secondary cooling zone below a mold of a continuous casthig machine, a cast slab drawn from a lower end of the mold is cooled by cooling water sprayed (or mixture of cooling water and air) from a spray nozzle disposed between two adjacent support rolls while being supported and transported by a plurality of pairs of support rolls.
[0003]
In the related art, in the continuous casting machine, in order to suppress bulging of the cast slab while increasing a drawing speed of the cast slab, a method is adopted in which a roll pitch is shortened using a small diameter roll as the support roll, and thus, the cast slab is supported by many support rolls. However, if the roll diameter of the support roll is decreased, not only rigidity of the support roll is decreased, but also sizes of bearings supporting both ends of the support roll are decreased, and thus, the cast slab cannot be sufficiently supported, and possibility of occurrence of the bulging is also increased.
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[0004]
Accordingly, in recent years, in order to suppress deformation of the small
diameter roll and decrease a bearing load, a divided roll is adopted as the support rolL
In the divided roll, a roll portion contacting the cast slab is divided in plural in a cast
slab width direction, a bearing portion is provided_between the adjacent divided roll
portions, and thus, an intermediate portion of the support roll asweiras.both'end& -
thereof is supported. As the number of division of the divided roll or a positioh
(division position) of the bearing portion, some types are suggested. _ _ ^
[0005] . "
For example, in Patent Document 1, it is suggested that divided rolls in which
a roll portion is divided into two are used, and the division positions (bearing
positions) of two divided rolls adjacent in a transport direction of the cast slab are
disposed (disposed in a so-called zigzag) to be deviated from each other in the width
direction of the cast slab. Moreover, in Patent Document 2, it is suggested that
divided rolls in which a roll p.ortion is divided into three are used, a groove portion is
provided on a circumferential surface of each of the divided roll portions; a cooling -
water flowing downward is dispersed, and thus, overcooling of the cast slab at-the
bearing portion is prevented. . -
[Prior Art Document] ._ _
[Patent Document] - - _.
[0006]
[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2005-14029
[Patent Document 2] Japanese Unexamined Patent Application, First
Publication No. H08-47757 -'
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-^i

[Disclosure of the Invention] [Problems to be Solved by the Invention]
[0007]
However, in the above-described divided roll, the bearing portion which does not contact the cast slab is disposed at the intermediate portion of the roll. Accordingly, after the cooling water sprayed from the nozzle to the cast slab flows down along a cast slab surface, the cooling water flows not only to both ends of the roll but also to the downstream side through the bearing portion which is the intermediate portion of the roll. Hereinafter, the cooling water flowing to the downstream side from the bearing portion is referred to as dripping water.
[0008]
Moreover, a space having a wedge-shaped cross-section surrounded by the circumferential surface of the roll and the cast slab surface exists immediately above a contact location between the roil and the cast slab. After the cooling water sprayed from the nozzle to the cast slab surface flows down along the cast slab surface, the cooling water stays in the space for a short while, and thereafter, the cooling water flows down from the bearing portion or both ends of the roll. Hereinafter, the cooling water staying in the space on the roll is referred to as stagnant water.
[0009]
The inventors have studied the above described circumstance intensively, and they have come to understand that if the cooling water (hereinafter, referred to as spray water) sprayed from the nozzle directly contacts the dripping water and interferes with the dripping water, a heat transfer coefficient between the cast slab and the spray water is increased, and the east slab is overcooled. In addition, the inventors have found that if the spray water directly contacts the stagnant water on the upper portion of the

roll and interferes with the stagnant water, the heat transfer coefficient between the cast slab and the spray water at the interference portion is increased, and the cast slab is overcooled. In this way, if the spray water interferes with the dripping water or the stagnant water and the heat transfer coefficient is increased, only the interference portion of the cast slab is overcooled, and thus, cooling uniformity in a cast slab width direction is significantly decreased. As described above, it has become clear recently that due to a relationship between the position of the bearing portion of the divided roll and a spray position (disposition of the nozzle) of the cooling water, the cooling in the cast slab width direction becomes non-uniform. In this way, if the cooling becomes non-uniform, solidification of the cast slab is non-uniform, and there are disadvantages such as cracks occurring in the cast slab or center segregation deteriorating.
[0010]
In addition, in Patent Document 2, a problem of the overcooling due to the dripping water is described. However, Patent Document 2 discloses the problem that the cast slab of a portion opposing the bearing portion contacts the dripping water flowing down through the bearing portion, and thus, only the cast slab of the contact portion is overcooled. Accordingly, in Patent Document 2, the problems of the spray water interfering with the dripping water and the overcooling occunlng due to the increase of the heat transfer coefficient of the interference portion, or the solutions for the problems are neither described nor suggested.
[0011]
The present invention is made in consideration of the above-described problems, and an object thereof is to provide a secondary cooling apparatus of a continuous casting machine and a secondary cooling method capable of improving cooling uniformity in a width direction of a cast slab supported and transported by a
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support roll in a secondary cooling zone below a mold of the continuous casting
machine.
[Means for Solving the Problem]
[0012]
The present invention adopts the following means to solve the problems and to achieve the object.
(1) According to an aspect of the present invention, there is provided a
secondary cooling apparatus of a continuous casting machine, including: a plurality of
pairs of support rolls which support a cast slab from both sides in a thickness direction
of the cast slab in a secondary cooling zone below a moid of the continuous casting
machine; and a plurality of nozzles which are disposed with an interval to one another
in the width direction of the cast slab between the support rolls arranged adjacent to
each other along a transport direction of the cast slab, and spray cooling water to the
cast slab. Moreover, each support roil includes: a roll shaft; a plurality of roil
portions which are provided on the roll shaft and divided in the width direction; and a
groove portion which is provided between the plurality of roll portions and through
which the cooling water can flow down. In addition, the groove portions, which are
each provided on an upstream side support roll and a downstream side support roll
adjacent in the transport direction, are disposed to be deviated from each other in the
width direction, and a first nozzle among the plurality of nozzles is disposed at a first
nozzle position which is set between the roll portion provided on the upstream side
support roll and the groove portion provided on the downstream side support roll.
[0013]
(2) In the seconda'ry cooling apparatus of a continuous casting machine
according to (1), a second nozzle among the plurality of nozzles may be disposed at a
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second nozzle position which is set between the groove portion provided on the upstream side support roll and the roll portion provided on the downstream side support roll, and a water quantity of the cooling water sprayed from the second nozzle may be less than a water quantity of the cooling water sprayed from the first nozzle. [0014]
(3) In the secondary cooling apparatus of a continuous casting machine
according to (2), a third nozzle among the plurality of nozzles may be disposed at a
third nozzle position which is set at a position other than the first nozzle position and
the second nozzle position between the upstream side support roll and the downstream
side support roll, and a water quantity of the cooling water sprayed from the third
nozzle may be less than the water quantity of the cooling water sprayed from the first
nozzle and be greater than the water quantity of the cooling water sprayed from the
second nozzle.
[0015]
(4) In the secondary cooling apparatus of a continuous casting machine
according to any one of (1) to (3), a bearing portion which supports the roll shaft may
be provided between the plurality of roll portions of each support roll, and the groove
portion may include the bearing portion.
[0016]
(5) In the secondary cooling apparatus of a continuous casting machine
according to any one of (1) to (3), the groove portion may include a water passing slit
which is formed on a circumferential surface of the support roll.
[0017]
(6) According to another aspect of the present invention, there is provided a
secondary cooling method in which a plurality of pairs of support rolls are provided,
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which support a cast slab from both sides in a thickness direction of the cast slab in a secondary cooling zone below a mold of a continuous casting machine, and include a plurality of roll portions divided in a width direction of the cast slab and a groove portion which is provided between the plurality of roll portions and through which a cooling water can flow down, and in a situation where the gi'oove portions, which are each provided on an upstream side support roll and a downstream side support roll arranged adjacent to each other along a transport direction of the cast slab, are disposed to be deviated from each other in the width direction, the cast slab transported by the support rolls is cooled, including: spraying the cooling water to the cast slab from a first nozzle position between the roll portion provided on the upstream side support roll and the groove portion provided on the downstream side support roll. [0018]
(7) The secondaiy cooling method according to (6), may further including:
spraying the cooling water to the cast slab with a water quantity less than a water
quantity of the cooling water sprayed from the first nozzle position from a second.
nozzle position between the groove portion provided on the upstream side support roil
and the roll portion provided on the downstream side support roll.
[0019]
(8) The secondary cooling method according to (7), may further including:
spraying the cooling water to the cast slab with a water quantity which is less than the
water quantity of the cooling water sprayed from the first nozzle and is greater than the
water quantity of the cooling water sprayed from the second nozzle, from a third
nozzle position other tiian the first nozzle position and the second nozzle position
between tlie upstream side support roll and the downstream side support roll.
[Effects of tlie Invention]
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[0020]
According to the aspects of the present invention, the cooling water sprayed to tiie cast slab above each support roll flows down through the groove portion of each support roll and becomes dripping water, and the cooling water stays in a space between the upper portion of each support roll and the cast slab, and stagnant water is generated. However, since the first nozzle is disposed at the first nozzle position which is set between the roll portion provided on the upstream side support roll and the groove portion provided on the downstream side support roll, the cooling water sprayed from the first nozzle does not directly contact the dripping water or the stagnant water, and thus, interference between the cooling water and the dripping water and the stagnant water can be suppressed. Accordingly, since a heat transfer coefficient between the cast slab and the cooling water is not increased at the portion of the cast slab corresponding to the first nozzle position, overcooling can be prevented.
Moreover, when the second nozzle is disposed at the second nozzle position which is set between the groove portion provided on the upstream side support roll and the roll portion provided on the downstream side support roll, the cooling water sprayed from the second nozzle directly contacts the dripping water flowing down through the groove portion of the upstream side support roll and the dripping water collected on the downstream side support roll, and thus, the cooling water and the dripping water interfere with each other. However, if the second nozzle is not disposed at the second nozzle position, the interference between the dripping water and the stagnant water can be avoided at the portion of the cast slab corresponding to the second nozzle position. Alternatively, the cooling water is sprayed from the second nozzle disposed at the second nozzle position with the water quantity less than the water quantity of the first nozzle disposed at the first nozzle position, and thus, the

interference between the cooling water and the dripping water and the stagnant water can be suppressed at the portion of the cast slab corresponding to the second nozzle position. Accordingly, since the increase of the heat transfer coefficient between the cast slab and the cooling water at the portion of the cast slab corresponding to the second nozzle position can be prevented or reduced, overcooling can be suppressed.
As described above, according to the present invention, in the secondary cooling zone below the mold of the continuous casting machine, disposition of the nozzles or the water quantity of the cooling water is appropriately adjusted according to an occurrence location of the dripping water or the stagnant water, and thus, cooling uniformity in the width direction of the cast slab supported and transported by the support rolls can be improved. [Brief Description of the Drawing]
[0021]
FIG. 1 is a side cross-sectional view showing a continuouscasting machine according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing support rolls and nozzles of a secondary cooling apparatus of the continuous casting machine according to the first embodiment.
FIG. 3 is a longitudinal cross-sectional view showing an interference state between stagnant water and spray water.
FIG. 4 is a longitudinal cross-sectional view showing an interference state between dripping water and the spray water.
FiG. 5 is a front view showing an interference state between the dripping water and the stagnant water, and the spray water.
FIG. 6A is a front view schematically showing a measurement condition of spray test:
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FIG. 6B is a side view schematically showing the measurement condition of the spray test.
FIG. 7 is a graph showing an increase ratio of a heat transfer coefficient obtained by the spray test.
FIG. 8A is a front view schematically showing the measurement condition of the spray test.
FIG. 8B is a side view schematically showing the measurement condition of the spray test.
FIG. 9 is a graph showing the increase ratio of the heat transfer coefficient obtained by the spray test.
FIG. 10 is a front view showing the disposition of the support rolls and the nozzles of the secondary cooling apparatus according to the first embodiment.
FIG. 11 is a front view showing disposition of support rolls and nozzles of a secondary cooling apparatus according to a second embodiment of the present invention.
FIG. 12 is a front view showing disposition of support rolls and nozzles of a secondary cooling apparatus according to a third embodiment of the present invention.
FIG 13 is a graph showing a measurement result of a cast slab surface temperature according to an example of the present invention.
FIG. 14A is a distribution view showing a simulation result of the east slab surface temperature in a comparative example.
FIG. 14B is a distribution view showing the simulation result of the cast slab surface temperature in an example of the present invention.
FIG. 15A is a distribution view showing a simulation result of a center solid phase rate of the.cast slab in a comparative example.,
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FIG. 15B is a distribution view showing the simulation result of the center solid phase rate of the cast slab in an example of the present invention. [Embodiments of the Invention]
[0022]
Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. Moreover, in the present specification and the drawings, the same reference numerals are attached to components having the substantially same functional compositions, and the overlapped descriptions are omitted.
[0023]
[1. First Embodiment]
[1.1. Overall Configuration of Continuous Casting Machine]
First, an overall configuration of a continuous casting machine according to a first embodiment of the present invention will be described with reference to FIG. 1. FIG. I is a side cross-sectional view showing the continuous casting machine according to the present embodiment.
[0024]
As shown in FIG. I, the continuous casting machine is an apparatus in which molten metal 2 (for example, molten steel) is continuously cast using a continuous casting mold I and a cast slab 3 such as a slab is manufactured. The continuous casting machine includes the mold I, a ladle 4, a tundish 5, a dipping nozzle 6, a secondary cooling apparatus 7, and a cast slab cutter 8.
[0025]
The ladle 4 is a movable container for transporting molten metal 2 from the outside to the tundish 5. . The ladle 4 is disposed above the tundish 5, and the molten
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metal 2 in the ladle 4 is supplied to the tundish 5. The tundish 5 is disposed above the mold I and accumulates the molten metal 2, and thus, inclusions in the molten metal 2 are removed. The dipping nozzle 6 downwardly extends from a lower end of the tundish 5 toward the mold 1, and a tip of the dipping nozzle 6 is immersed in the molten metal 2 in the mold 1. The dipping nozzle 6 continuously supplies the molten metal 2, in which the inclusions are removed in the tundish 5, into the mold 1.
[0026]
The mold 1 is formed in a rectangular tubular shape according to a width and a thickness of the cast slab 3, and for example, is assembled by interposing a pair of short-side mold plates between a pair of long-side mold plates from both sides in the width direction. For example, the mold plates are configured to have copper plates having a water cooling mechanism. The mold 1 cools the molten metal 2 contacting the mold plates, and manufactures the cast slab 3 which includes a non-solidified portion 3b in an inner portion of an outer solidified shell 3a. As the solidified shell 3a moves below the mold 1, solidification of the inner non-solidified portion 3b proceeds, and a thickness of the outer solidified shell 3a is gradually thickened. The cast slab 3 including the solidified shell 3a and the non-solidified portion 3b is drawn from the lower end of the mold 1.
[0027]
The secondary cooling apparatus 7 is provided in a secondary cooling zone 9 below the mold I, and cools the cast slab 3 drawn from the lower end of the mold 1 while supporting and transporting the cast slab 3. The secondary cooling apparatus 7 includes a plurality of pairs of support rolls 10 (for example, non-driven support rolls 11, pinch rolls 12, and segment rolls 13) which are disposed at both sides in a thickness direction of the cast slab 3, and a plurality of spray nozzles (not shown) which spray
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cooling water to the cast slab 3.
[0028]
The support rolls 10 included in the secondary cooling apparatus 7 are disposed to be paired on both sides in the thickness direction of the cast slab 3, and function as a support-transport unit which transports the cast slab 3 while supporting the slab. Since the cast slab 3 is supported from botlrsides in the thickness direction by each support roll 10, breakout or bulging of the cast slab 3 during the solidification in the secondary cooling zone 9 can be prevented.
[0029]
For example, each support roll 10 includes the non-driven support rolls 11, the pinch rolls 12, and the segment rolls 13 shown in FIG. I. The non- driven support rolls 11, the pinch rolls 12, and the segment rolls 13 forma transport path (pass line) of the cast slab 3 in the secondary cooling zone 9. As shown in FIG. 1, the pass line is vertical immediately below the mold I, subsequently is bent in a curved shape, and finally, becomes horizontal. In secondary cooling zone 9, the portion in which the pass line is vertical is referred to as a vertical portion 9A, the portion in which the pass line is bent is referred to as a bent portion 9B, and the portion in which the pass line is horizontal is referred to as a horizontal portion 9C. In this way, the continuous casting machine including the pass line is referred to as a vertical bending continuous casting machine. Moreover, the secondary cooling apparatus of the present invention is not limited to the above-described vertical bending type continuous casting machine, and various types of continuous casting machines such as a bent type or a vertical type may be adopted.
[0030] .. Here, the non-driven support rolls 11, the pinch rolls 12, and the segment rolls
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13 will be described. The non-driven support rolls 11 are non-driven type rolls provided in the vertical portion 9A immediately below the mold I and support the cast slab 3 immediately after being drawn from the mold 1. In the cast slab 3 immediately after being drawn from the mold 1, since the solidified shell 3a is thin, it is necessary to support the cast slab 3 at relatively short intervals (roll pitches) to prevent the breakout or the bulging. Accordingly, it is preferable that a small-diameter roll capable of decreasing the roll pitch be used as the non-driven support roll 11. In the example of FIG. 1, three pairs of non-driven support rolls 11 configured to have small-diameter rolls are provided on both sides of the cast slab 3 in the vertical portion 9A at a relatively narrow roll pitch.
[0031]
The pinch roils 12 are drive type rolls which are rotated by a driving unit such as a motor and have a function which draws the cast slab 3 from the mold 1. The pinch rolls 12 are disposed at appropriate positions of the vertical portion 9A, the bent portion 9B, and the horizontal portion 9C. The cast slab 3 is drawn from the mold 1 by forces transmitted from the pinch roils 12 and is transported along the pass line. Moreover, the disposition of the pinch rolls 12 is not limited to the example shown in FIG. 1, and may be arbitrarily set.
[0032]
The segment rolls 13 (may be also referred to as guide rolls) are non-driven type rolls which are provided in the bent portion 9B and the horizontal portion 9C, and support and guide the cast slab 3 along the pass line. The segment rolls 13 may be disposed with roll diameters and roll pitches different from one another at positions on the pass line, or may be disposed with roll diameters and roll pitches different from one another on a F surface (Fixed Surface and.a lower left surface in FIG, 1) and a L .
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surface (Loose Surface and a upper right surface in FIG. 1) of the cast slab 3.
[0033]
The cast slab cutter 8 is disposed at a terminal of the horizontal portion 9C of the pass line, and cuts the cast slab 3, which is transported along the pass line, to a predetermined length. The cut cast slab 14 having a thick plate shape is transported to facilities of the next process by table rolls 15. . [0034]
Next, an operation of the continuous casting machine having the above-described configuration will be described. The molten metal 2 transported from the ladle 4 is supplied to the tundish 5, and the inclusions of the molten metal 2 are removed. Subsequently, the molten metal 2 in the tundish 5 is injected into the mold 1 through the dipping nozzle 6.
[0035]
In the mold 1, the outer circumferential portion of the molten metal 2 ■contacting the inner surface of the mold I' is solidified, the solidified shell 3a is formed, the solidification gradually proceeds toward the lower portion of the mold 1, and the thickness of the solidified shell 3a is increased. Moreover, the cast slab 3 is drawn below the moid 1 in a state where the non-solidified portion 3b exists in the solidified shell 3a.
[0036]
Subsequently, in the secondary cooling zone 9 below the mold I, the cast slab 3 drawn from the mold 1 is gradually cooled while being supported and transported along the vertical bending pass line by the plurality of pairs of support rolls 10 (11, 12, and 13) of the secondary cooling apparatus 7. Accordingly, the solidification of the non-solidified portion 3b inside the cast slab 3 further proceeds, and the solidification
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is completed at a crater end 3c. Thereafter, the cast slab 3, in which the solidification is completed, is cut to a cast slab 14 having a predetermined length by the cast slab cutter 8, and is carried out to the outside.
[0037]
Moreover, kinds and sizes of the cast slabs 3 manufactured by the continuous casting machine are not particularly limited. For example, the cast slab 3 may be a slab having a thickness of approximately 250 mm to 300 mm, may be a bloom or a billet in which the thickness exceeds 500 mm, may be a thin slab having a thickness of approximately 100 mm, or may be a thin band continuous cast slab in which the thickness is 50 mm or less. In addition, for example, a material of the cast slab 3 may be various metals, on which the continuous casting can be preformed, such as aluminum, aluminum alloy, or titanium, in addition to steel and special steel.
[0038]
[1.2. Configuration of Secondaiy Cooling Apparatus]
Next, a configuration of the secondary cooling apparatus 7 of the continuous casting machine according to the present embodiment will be described with reference to FIG. 2. FIG 2 is a perspective view showing the support rolls 10 and the nozzles 20 of the secondary cooling apparatus 7 of the continuous casting machine according to the present embodiment.
[0039]
As shown in FIG. 2, the secondary cooling apparatus 7 according to the
present embodiment includes the plurality of pairs of support rolls 10 which support
the cast slab 3 from both sides in the thickness direction of the cast slab 3 in the
secondary cooling zone 9 below the mold 1, and the plurality of nozzles 20 which
spray the. cooling water to cast slab 3 . .-. . .,
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[0040]
The support roll 10 is a general term of the non-driven support roll 11, the pinch roll 12, the segment roil 13, or the like shown in FIG. 1. The support rolls 10 are disposed to be paired on both sides in the thickness direction of the cast slab 3, and have a function which supports the cast slab 3 from both sides. Moreover, the support rolls 10 are rotated according to the movement of the cast slab 3, and have a function which guides and transports the cast slab 3 along a predetermined pass line. The plurality pairs of support rolls 10 are disposed at both sides of the pass line, and thus, bulging in which a center portion in a width direction of the cast slab 3 swells, or breakout due to fracture of the solidified shell 3a can be prevented.
[0041]
The support rolls 10 are disposed with a predetemiined interval to each other along a transport direction (the lower side in FIG. 2) of the cast slab 3 in both sides of the cast slab 3. At this time, since the cast slab 3 can be preferably supported when the interval of the support rolls 10 arranged adjacent to each other along the transport direction is narrowed, it is preferable that a smail-diameter roll be used if possible as the support roll 10 to narrow the interval. However, if the support roll 10 is the smail-diameter roll, rigidity of the roil is decreased, diameters of bearing portions (not shown) in both sides of the roll are also decreased, and thus, the center portion of the roll is easily bent toward the outside.
[0042]
Accordingly, as shown in FIG. 2, in tlie support roll 10 according to the present embodiment, a divided roll is used in which a roll portion (body portion) contacting the cast slab 3 is divided in plural in the width direction of the cast slab 3 (hereinafter, referred to as a cast slab width direction). The number of divisions of
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the roll portion is an arbitrary number which is 2 or more. However, in FIG. 2, the example of the divided roll in which the roll portion is divided into three portions is shown. Since the divided roll is used, bearings are set not only to both ends of the roll but also to an intermediate portion of the roll, and the intermediate portion of the support roll 10 can be also supported. Thus, bending of the support roll 10 can be preferably suppressed.
[0043]
As shown in FIG. 2, each support roll 10 configured to have the divided roll includes one roll shaft 101, a plurality of divided roil portions 102 (corresponding to the roll portion) divided into the cast slab width direction, and one or two or more bearing portions 103 (corresponding to a groove portion) provided between two divided roll portions 102 adjacent in the cast slab width direction. In a three-divided roll of the shown example, three divided roll portions 102 and two bearing portions 103 are provided around one roll shaft 101.
[0044]
The roil shaft 101 is one rotating shaft or a pluralit>' of rotating shafts extending in the cast slab width direction, and the plurality of divided roll portions 102 are fixed to the roll shaft 101. The roll shaft 101 is one when the support roll 10 is a drive roll, but the roll shaft 101 may be divided into multiple parts when the support roll 10 is a non-driven roll, and divided roll shafts may be supported by the bearing portions 103, respectively. The divided roll portions 102 rotate while contacting the cast slab 3, and thus, support the cast slab 3.
[0045]
The bearing portions 103 are provided between the adjacent divided roll portions 102 and are examples-of a grooves.portion through which the cooling water
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can flow down. The tips of the bearing portions 103 are rotatably mounted on the roll shaft 101, and the rear ends of the bearing portions 103 are fixed to support members (for example, back frames) which are not shown. Accordingly, the bearing portions 103 support the intermediate portions of the support roll 10, and the intermediate portions of the support roll 10 are prevented from being bent in a direction separated from the cast slab 3. Moreover, the tips of the bearing portions 103 do not contact with the cast slab 3, and gaps 105 exist between the tips of the bearing portions 103 and the cast slab 3. After the cooling water sprayed from the nozzle 20 described below collides with a surface 3d of the cast slab 3, the cooling water does not pass through the positions of the divided roll portions 102 contacting the cast slab 3, and thus, the cooling water intensively flows down through the gaps 105 of the bearing portions 103 and becomes dripping water.
[0046]
Moreover, positions in a horizontal direction of the bearing portions 103 (the division positions of the divided rolls) in each support roll 10 are arbitrary. However, the bearing portions 103 (that is, groove portions), which are each provided on an upstream side support roll 10 and a downstream side support roll 10 adjacent in the transport direction of the cast slab 3, are disposed to be deviated from each other in the cast slab width direction. Hereinafter, this disposition may be referred to as a zigzag disposition.
That is, horizontal positions (position A) of the bearing portions 103 of the most upstream side support roll 10 shown in FIG. 2 are deviated from horizontal positions (position B) of the bearing portions 103 of the center support roll 10. Moreover, the horizontal positions (position B) of the bearing portions 103 of the center support roil 10 are also deviated from horizontal positions (position A) of the
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bearing portions 103 of the most downstream side support roll 10.
In addition, in FIG. 10, the groove portions (bearing portions 103) provided on the upstream side support roll 10 and the gi-oove portions (bearing portions 103) provided on the downstream side support roll 10 are disposed zigzag so as not to be completely overlapped with each other when viewed from the transport direction.
The disposition is not limited to the zigzag disposition, and as shown in FIG. 11 described below, the upstream side groove portions and the downstream side groove portions may be disposed zigzag so as to be partially overlapped with each other when viewed from the transport direction. That is, the zigzag disposition in the present embodiment (that is, the upstream side groove portions and the downstream side groove portions being disposed so as to be deviated in the cast slab width direction) is a concept allowing both groove portions to partially overlap with each other when viewed from the transport direction.
[0047]
In this way, in the present embodiment, the bearing portions 103 (that is, the groove portions through which the cooling water can pass), which are provided at each of the upstream side support roll 10 and the downstream side support roll 10 adjacent in the transport direction, are disposed (are disposed zigzag) to be deviated from each other in the cast slab width direction. Accordingly, the support portions of the cast slab 3, which are supported by the plurality of support rolls 10 adjacent to one another in the transport direction, are dispersed in the cast slab width direction, and the support of the cast slab 3 by the plurality of support rolls 10 can be uniformized. In addition, by adopting the zigzag disposition, the positions of the dripping water flowing down through the bearing portions 103 of each support roll 10 can be deviated in the cast slab width direction. Accordingly, only thcsame portion in the width direction of the
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cast slab 3 is prevented from being locally overcooled by the dripping water, and thus, cooling uniformity in the cast slab width direction can be improved.
[0048]
Moreover, the horizontal positions (position A) of the bearing portions 103 of the most upstream side support roll 10 shown in FIG. 2 are the same as the horizontal positions (position A) of the bearing portions 103, 103 of the most downstream side support roll 10. Accordingly, in the example shown in FIG. 2, in the plurality of support rolls 10 which are arranged along the transport direction: of the cast slab 3, the positions of the bearing portions 103 become the zigzag disposition which is repeatedly deviated every two support rolls such as the position A, the position B, the position A, and the position B (hereinafter, repetition of the positions A and B). However, the zigzag disposition of the present invention is not limited to this example. For example, the zigzag disposition may be repeatedly deviated every three support roils such as the position A, the position B, the position C, the position A, the position B, and position C (hereinafter, repetition of the positions A, B, and C), and similarly, may be repeatedly deviated every four or more support rolls. In addition, a zigzag disposition, which is irregularly deviated without periodicity such as the position A, the position B, the position C, a position D, and a position E (hereinafter, repetition of arbitrary positions), may be adopted.
[0049]
In the support roll 10 having the above-described configuration, both ends of the roll shaft 101 are supported by bearing portions (not shown), and the intermediate portion of the roll shaft 101 is installed in the state where the intermediate portion is supported by the bearing portions 103. Accordingly, circumferential surfaces of the plurality of divided roll portions 102 contact the cast slab 3, and thus, the cast slab 3 is
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supported. At this time, since the cast slab 3 moves in the transport direction, the divided roll portions 102 rotate along the roll shafts 101 according to the movement of the cast slab 3.
[0050]
Next, nozzles 20 of the secondaiy cooling apparatus 7 according to the present embodiment will be described. As shown in FIG. 2, the nozzles 20 are configured to have spray nozzles which spray a mixture of the cooling water and air toward the cast slab 3 in a spray shape. The nozzles 20 are connected to a cooling water supply unit (not shown), the cooling water and the air are supplied from the cooling water supply unit to the nozzles 20 at a predetermined supply pressure, and thus, the coohng water and the air are sprayed from the nozzles 20 to the cast slab 3. A water quantity q of the cooling water sprayed from the nozzles 20 can be controlled by adjusting supply amounts of the cooling water to the nozzles 20, sizes of spray ports of the nozzles 20, or the iike.
., , [0051] . - -
In addition, the nozzles 20 according to the present embodiment spray the mixture of the cooling water and the air as a coolant. However, hereinafter, for convenience of the descriptions, it is described that the cooling water is sprayed as the coolant. Moreover, for example, the coolant (fluid) sprayed from the nozzles 20 may be combination of the cooling water and nitrogen, combination of the cooling water, a surface active agent, and the like, or only the cooling water, in addition to the combination of the cooling water and the air.
[0052]
The plurality of nozzles 20 are disposed with an interval in the cast slab width direction.in a region (hereinafteivreferred to as a inter-roll region).between the. . ,.
- 22

upstream side support roll 10 and the downstream side support roll 10 adjacent in the transport direction of the cast slab 3. In the example of FIG. 2, six nozzles 20 are disposed at an equal interval in the cast slab width direction. However, the present invention is not limited to the example, and the number of the installed nozzles 20 may be an arbitrary number if the number is in plural, and the disposition interval of the nozzles 20 may be arbitraiy.
[0053]
In this way, the nozzles 20 are disposed at the inter-roU region between the upstream side support roll 10 and the downstream side support roll 10 adjacent in the transport direction, and spray the cooling water from the disposition positions to the cast slab 3. The cooling water sprayed from the nozzles 20 collides with the cast slab 3, and flows down along the surface 3d of the cast slab 3. Accordingly, heat exchange between the cooling water and the cast slab 3 is generated, and thus, the cast slab 3 is cooled.
. [0054] ,
[1.3. Adverse Effect of Dripping Water and Stagnant Water]
Next, the inventors have reviewed adverse effects of forced cooling due to interference between the dripping water and the stagnant water, and the spray water, and the results will be described in details.
[0055]
The inventors have studied intensively, and determined that if the cooling water (spray water) sprayed from the nozzles 20 interfered with the dripping water and the stagnant water, a heat transfer coefficient between the cooling water and the cast slab 3 at the interference position was increased, and local.forced cooling was generated in the .cast slab 3. Hereinafteiva phenomenoiLof the forced coolingwill be
- 23 -

described.
[0056]
[1.3.1. Interference State between Stagnant Water and Spray Water]
First, an interference state between the stagnant water and the spray water will be described with reference to FIG. 3. FIG. 3 is a longitudinal cross-sectional view showing the interference state between the stagnant water 30 and the spray water 21. Moreover, hereinafter, in two support roils 10 adjacent in the transport direction (vertical direction), the upstream side support roll 10 in the transport direction is referred to as an upper roll 10, and the downstream side support roll 10 is referred to as a lower roll 10. Tn addition, the cooling water sprayed from the nozzles 20 is referred to as spray water 21.
[0057]
As shown in FIG. 3, after the spray water21, which is sprayed from the nozzle 20 disposed at the inter-roll region between the upper roll 10 and the lower roll 10, collides with the surface 3d of the cast slab 3, the spray water flows down along the surface 3d. The divided roll portion 102 of the lower roll 10 contacts the cast slab 3 and impedes passing of the cooling water flowing down along the surface 3d of the cast slab 3. Accordingly, the cooling water flowing down along the surface 3d of the cast slab 3 is collected in a space having a wedge-shaped cross-section which is surrounded by a circumferential surface 102a of the cast slab 3 side above the divided roll portion 102 of the lower roll 10 and the surface 3d of the cast slab 3, and thus, the stagnant water 30 is generated.
[0058]
If the spray water 21 from the nozzle 20 directly contacts the stagnant water 30 which is collected betAveen the-circumfei'ential surface 102a of the divided roll ..
- 24 -

portion 102 and the surface 3d of the cast slab 3 as described above, the spray water 21 and the stagnant water 30 interfere with each other, and the heat transfer coefficient between the cooling water and the cast slab 3 in the interference range 31 is increased. In the example of FIG. 3, the lower side of the spray water 21 and the stagnant water 30 on the lower roll 10 interfere with each other at the interference range 31.
[0059]
As a result, the cast slab 3 is forcibly cooled locally at the position corresponding to the interference range 31, and thus, cooling uniformity in the cast slab width direction is inhibited. It is considered that the reason for the heat transfer coefficient being increased from the interference between the stagnant water 30 and the spray water 21 is that the sprayed water density at the interference range 31 is increased by the stagnant water 30, and thus, convection heat transfer is promoted due to turbulence of the stagnant water 30 in the interference range 31 by the spray water 21. In general, the heat transfer coefficient between water and an object to be cooled is represented from function of the sprayed water density. As the sprayed water density is increased, the heat transfer coefficient is increased, and thus, a temperature change of the object to be cooled is severe.
[0060]
[1.3.2. Interference State between Dripping Water and Spray Water]
Next, an interference between the dripping water and the spray water will be described with reference to FIGS 4 and 5. FIG. 4 is a longitudinal cross-sectional view showing the interference state between the dripping water 32 and the stagnant water 30, and the spray water 21. FIG. 5 is a front view showing an interference state between the dripping water 32 and the stagnant water 30, and the spray water 21.
[0061] ..
- 25 '

As described above, when the support roll 10 is configured to have the divided rolls shown in FIG. 2, the bearing portions 103 which do not contact the cast slab 3 become the groove portions (water passing portions) through which the cooling water can flow down. Accordingly, the stagnant water 30 collected at the upper portion of the divided roll portion 102 of the upper roll 10 moves in the cast slab width direction toward the bearing portion 103, and as shown in FIGS. 4 and 5, the cooling water intensively flows down through the gap 105 between the tip I03a of the bearing portion 103 and the surface 3d of the cast slab 3. In this way, the cooling water flowing down from the positions of the bearing portions 103 is the dripping water 32. If the dripping water 32 flows down to the vicinity of the lower roll 10, the dripping water becomes the stagnant water 30 on the divided roll portions 102 of the lower roll 10.
[0062]
If the spray water 21 sprayed from the nozzles 20 disposed between the upper roll 10 and the lower roll 10 directly contacts the dripping water 32, then the spray water 21 and the dripping water 32 interfere with each other, and thus, the heat transfer coeffiicient between the cooling water and the cast slab 3 in the interference range 33 is increased. In the example of FIGS. 4 and 5, the upper portion side of the spray water 21 and the dripping water 32 interfere with each other in the interference range 33, and the lower portion side of the spray water 21 also interferes with the stagnant water 30 on the lower roll 10 in the interference range 31.
[0063]
As a result, the cast slab 3 is forcibly cooled locally at the position corresponding to the interference range 33 of the spray water 21 and the dripping water 32, and thus, cooling uniformity in the cast slab width direction is inhibited. In this
- 26 -

way, it is considered that the reason for the heat transfer coefficient being increased from the interference between the dripping water 32 and the spray water 21 is that the sprayed water density in the interference range 33 is increased by the dripping water 32.
[0064]
[1.3.3. Increase of Heat Transfer Coefficient due to Interference between Spray Water and Stagnant Water]
Next, with reference to FIGS. 6A, 6B, and 7, in order to measure an increase amount of the heat transfer coefficient due to the interference between the spray water 21 and the stagnant water 30, a spray test of the spray water 21 is performed, and the result will be described. FIG. 6A is a front view schematically showing measurement conditions of the spray test. FIG. 6B is a side view schematically showing measurement conditions of the spray test. FIG. 7 is a graph showing an increase ratio of the heat transfer coefficient obtained by the spray test.
[0065]
As shown in FIG. 6A and 6B, two rolls.(upper.roll 10 and lower roll 10) were
disposed to be vertically arranged along a flat plate-like cast slab 3, and one nozzle 20
was disposed at the intermediate portion between both rolls 10 and 10. The water
quantity (sprayed quantity) of the spray water 21 sprayed from the nozzle 20 was set to
20 L/min. Moreover, as shown in FIGS. 6A and 6B, the spray range of the spray
water 21 was set to a laterally long elliptical shape. In addition, four measurement
points PA, PB, PC, and Pp were provided in the interference range 31 between the spray
water 21 and the stagnant water 30. The measurement point PA was positioned
immediately below the center of the nozzle 20, horizontal distances from the
measurement point PA to the measurement points PB, PC» ancf PD were set to 70 mm,
.140 mm, and 2I,0-mm, respectively. - . - _ .
- 27 -

[0066]
Under the above-described conditions, the spray water 21 was sprayed from the nozzle 20, the spray water interfered with the stagnant water 30 on the lower roll 10, and a test measuring the heat transfer coefficient h between the cast slab 3 and the cooling water at each of the measurement points PA, PB, PC, and PD was performed three times (tests 1 to 3). Moreover, for comparison, the spray water 21 was sprayed from the nozzle 20 in a state where the stagnant water 30 was not present on the lower roll 10, and a heat transfer coefficient ho between the cast slab 3 and the spray water 21 at each of the measurement points PA, PB, PC, and PD was measured (when only the spray is applied without interference).
[0067]
The measurement results of the heat transfer coefficients measured by the spray tests are shown in FIG. 7. In FIG. 7, a vertical axis indicates a vaUie k! (kl = h/ho) which is obtained by dividing the heat transfer coefficient h measured at the tests 1 to 3 by the heat transfer coefficient ho measured at the case of application of only the spray without the interference.
[0068]
As shown in FIG 7, the heat transfer coefficient h wheiUhe spray water 21 and the stagnant water 30 interfere with each other (tests 1 to 3) becomes 1.2 to 1.5 times of the heat transfer coefficient ho at the case of application of only the spray without interference, and is significantly increased. The increase ratio of the heat transfer coefficient h is approximately constant regardless of respective measurement points PA, PB, PC» and PD in which the distances from the center of the nozzle 20 are different from one another. According to the test results, the heat transfer coefficient between the cooling water .and the cast slab 3 issignificantly increased due to the
- 28 -

interference between the spray water 21 and the stagnant water 30, and it is demonstrated that the east slab 3 in the interference range 31 is forcibly cooled.
[0069]
[1.3.4. Increase of Heat Transfer Coefficient due to Interference between Spray Water and Dripping Water]
Next, with reference to FIGS. 8A, 8B, and 9, in order to measure an increase amount of the heat transfer coefficient due to the interference between the spray water 21 and the dripping water 32, a spray test of the spray water 21 is performed, and the result will be described. FIG. 8A is a front view schematically showing measurement conditions of the spray test. FIG. 8B is a side view schematically showing measurement conditions of the spray test. FIG. 9 is a graph showing an increase ratio of the heat transfer coefficient obtained by the spray test.
[0070]
As shown in FIGS. 8A and 8B, two rolls (upper roll 10 and lower roll 10) were disposed to be vertically arranged along a flat plate-like cast slab 3, the upper roll 10 was set to a two-divided roll, and the gap 105 between the bearing portion 103 and the cast slab 3 was structured so that the cooling water could flow down through the gap. Moreover, one nozzle 20a was disposed immediately above the bearing portion 103 above the upper roll 10, and another nozzle 20b was disposed immediately below the bearing portion 103 at the intermediate between the upper roll 10 and the lower roll 10. In addition, the water quantity (sprayed quantity) of the spray water 21 sprayed from each of the nozzles 20a and 20b was set to 20 L/min, and as shown in FIG. 8A and SB, the spray range of the spray water 21 had a laterally long elliptical shape.
[0071]
Under the. above-described conditions, the. spray water 21 was sprayed from .
- 29 -

the nozzle 20a, the dripping water 32 was generated in the bearing portion 103 of the upper roil 10, and the spray water 21 was sprayed from the nozzle 20b and interfered with the dripping water 32. Moreover, a test measuring an average value of the heat transfer coefficients h between the cast slab 3 and the cooling water in the spray range of the spray water 21 from the nozzie 20b was performed. Moreover, the similar tests were performed in plural times by changing the water quantity q of the spray water 21 from the nozzle 20b. In addition, for comparison, the spray water 21 was sprayed from the lower nozzle 20b in a state where the spray of the spray water 21 from the upper nozzle 20a stopped and the dripping water 32 was not present, and the heat transfer coefficient ho between the cast slab 3 and the spray water 21 was measured (when only the spray is applied without the interference).
[0072]
The measurement results of the heat transfer coefficients measured by the spray tests are shown in FIG. 9. In FIG. 9, a vertical axis indicates a value k2 (k2 = li/ho) which is obtained by dividing an average value of the heat transfer coefficients measured by the tests by the heat transfer coefficient ho measured at the case of application of only the spray without the interference. Moreover, in FIG. 9, a horizontal axis indicates a value k3 (k3 - Q/q) which is obtained by dividing the water quantity Q of the dripping water 32 measured by the tests by the water quantity q of the spray water 21 from the nozzle 20b.
[0073]
As shown in FIG. 9, the heat transfer coefficient h when the spray water 21 and the dripping water 32 interfere with each other (k3 = 0.2 to l.O) becomes i .14 to 1.52 times of the heat transfer coefficient ho at the case (k3 = 0) of application of only the spray without the interference, and is significantly increased. Particularly, as a
- 30 -

ratio k3 of the water quantity Q of the dripping water 32 with respect to the water quantity q of the spray water 21 is increased, the increase ratio of the heat transfer coefficient h is also increased. For example, when the water quantity Q of the dripping water 32 and the water quantity q of the spray water 21 are the same as each other (k3 = 1.0), the heat transfer coefficient h becomes approximately 1.5 times of the heat transfer coefficient ho. According to the test results, the heat transfer coefficient between the cooling water and the cast slab 3 is significantly increased due to the interference between the spray water 21 and the dripping water 32, and it is demonstrated that the cast slab 3 in the interference range 33 is forcibly cooied.
[0074]
[1.4. Nozzle Disposition and Water Quantity Control According to Position of Dripping Water and Stagnant Water]
Next, the disposition of nozzles 20 and a water quantity control, which are characteristics of the secondaiy cooling apparatus 7 according to the present embodiment, will be described in details.
[0075]
As described above, if the spray water 21 from the nozzles 20 interferes with the stagnant water 30 or the dripping water 32, the heat transfer coefficients in the interference ranges 31 and 32 are increased, the cast slab 3 is forcibly cooled, and thus, the cooling uniformity in the width direction of the cast slab 3 is decreased. An occurrence position of the stagnant water 30 or the dripping water 32, which causes the adverse effects, has a relationship with the positions of the groove portions provided in the support roil 10. The groove portions do not contact the cast slab 3 in the support roll 10, the cooling water can flow down through the groove portions, and for example, the groove portions.are the bearing portions 103, slits, or the like.. The stagnant water.
- J

30 occurs on the portion (that is, divided roll portion 102) in which the groove portion of the downstream side support roll 10 is not present, and the dripping water 32 occurs at the portion (that is, bearing portion 103) of the groove portion" of the upstream side support roll 10.
[0076]
Accordingly, in order to solve the problems, in the secondaiy cooling
apparatus 7 according to the present embodiment, the disposition of the nozzles 20 or
the water quantity of the spray water 21 from each nozzle 20 is adjusted according to
the positions of the groove portions (bearing portions 103, slits, or the lilce) provided
on the support roll 10. Accordingly, the spray water 21 interfering with the stagnant
water 30 or the dripping water 32 is suppressed as much as possible, and non-uniform
cooling in the width direction of the cast slab 3 due to the forced cooling can be
decreased. Hereinafter, the disposition of the nozzles 20 or the water quantity of the
cooling water from each nozzle 20 according to the present embodiment will be
described in details. - ,
[0077]
FIG. 10 is a front view showing the dispositions of the support rolls 10 and the nozzles 20 of the secondary cooling apparatus 7 according to the present embodiment. As shown in FIG. 10, each support roll 10 is configured to have a three-divided roll, and includes three divided roll portions 102 and two bearing portions 103 provided between three divided roll portions 102. In the support roils 10 adjacent vertically, the bearing portions 103 are disposed to be a zigzag shape to each other.
[0078]
Moreover, the plurality of nozzles 20 are disposed in the inter-roll region between the upstream side support roll 10 and the downstream sidesupportroll 10
- 32 -

adjacent in the transport direction, and are arranged at an equal interval in the cast slab width direction. According to the disposition position, the nozzle 20 is divided into a directly above nozzle 20A (first nozzle), a directly below nozzle 20B (second nozzle), and an intermediate nozzle 20C (third nozzle).
[0079]
The directly above nozzle 20A is a nozzle which is disposed at a position (that is, a first nozzle position which is set between the divided roll portion 102 provided on the upstream side support roll 10 and the bearing portion 103 (groove portion) provided on the downstream side support roll 10) immediately above the bearing portion 103 of the downstream side support roll 10 in the inter-roll region. Moreover, the directly above nozzle 20A according to the present embodiment is positioned immediately above the groove portion such as the bearing portion 103. However, the present invention is not limited to the example, the directly above nozzle may be disposed at a position at which the nozzle does not easily interfere with the dripping water 32 or the stagnant water 30 above the groove portion. Moreover, in the shown example, the directly above nozzle 20A is disposed immediately above only one bearing portion of two bearing portions 103 of each support roll 10. However, the directly above nozzles 20A may be disposed above all bearing portions 103, respectively.
[0080]
The directly below nozzle 20B is a nozzle which is disposed at a position (that is, a second nozzle position which is set between the bearing portion 103 (groove portion) provided on the upstream side support roll 10 and the divided roll portion 102 provided on the downstream side support roll 10) immediately below the bearing portion 103 of the .upstream side roll 10 inthe. inter-roll region.. .Moreover, the..-.. -. .
- 33 -

directly below nozzle 20B according to the present embodiment is positioned immediately below the groove portion such as the bearing portion 103, However, the present invention is not limited to the example, the nozzle 20, which is disposed at the position at which the nozzle interferes with the dripping water 32 or the stagnant water 30 below the groove portion, is also included in the directly below nozzle 20B. Moreover, in the shown example, the directly below nozzle 20B is disposed immediately below only one bearing portion of two bearing portions 103 of each support roll 10. However, the directly above nozzles 20B may be disposed below all bearing portions 103, respectively, or the directly below nozzle 20B may not be disposed below all bearing portions 103.
[0081]
The intermediate nozzle 20C is a nozzle which is disposed at a position (that is, a third nozzle position which is set at a position other than the fust nozzle position and the second nozzle position in the inter-roil region) between the divided roll portion 102 of the upstream side support roll 10 and the divided roll portion 102 of the downstream side support roll 10 in the inter-roll region. The groove portion such as the bearing portion 103 does not exist above or below the intermediate nozzle 20C, and the divided roll portion 102 exists above or below the intermediate nozzle 20C. Accordingly, a nozzle 20 other than the directly above nozzle 20A and the directly below nozzle 20B becomes the intermediate nozzle 20C.
[0082]
From the viewpoint of preventing the interference between the spray water 21, and the stagnant water 30 and the dripping water 32, it is most preferable to dispose the directly above nozzle 20A immediately above the bearing portion 103, and subsequently, it is, preferable to dispose the intermediate nozzle 20C between the upper
- 34 -

and lower divided roll portions 102. Moreover, from the viewpoint, it is preferable to adjust the spray water quantity qA of the directly above nozzle 20A to be most much and, subsequently, to adjust the spray water quantity qc of the intermediate nozzle 20C to be less than qA- On the other hand, it is preferable that the directly below nozzle 20B be not disposed immediately below the bearing portion 103. If the directly below nozzle 20B is disposed, it is preferable to make the spray water quantity qo of the directly below nozzle 20B be zero or be less as possible, and to adjust the water quantity qs to be less than qA and qc. Hereinafter, the reasons why the nozzle disposition and the spray water quantity q are set as described above will be described.
[0083]
First, advantages of depositing the directly above nozzle 20A will be described. Since the divided roll portion 102 of the upstream side support roll 10 (hereinafter, referred to as an upper roll 10) exists above the directly above nozzle 20A, the dripping water 32 does not occur in the spray range of the directly above nozzle 20A. Accordingly, the spray water 21 of the directly above nozzle 20A does not interfere with the dripping water 32. Moreover, since the bearing portion 103 of the downstream side support roll 10 (hereinafter, referred to as a lower roll 10) exists below the directly above nozzle 20A and the cooling water flows down from the bearing portion 103, the stagnant water 30 does not occur in the spray range of the directly above nozzle 20A. Accordingly, the spray water 21 of the directly above nozzle 20A almost does not interfere with the stagnant water 30.
[0084]
Therefore, even when the directly above nozzle 20A is installed and the spray water quantity qA is increased, the spray water 21 of the directly above nozzle 20A does not.interfere with the dripping water 32 or the stagnant water.30. Accordingly,.
- 35 -

the locally forced cooling of the cast slab 3 due to the increase of the heat transfer coefficient does not occur in the spray range of the spray water 21 of the directly above nozzle 20A. Therefore, the non-uniform cooling of the cast slab 3 in the spray range due to the spray water 21 of the directly above nozzle 20A does not occur, and thus, uniform cooling can be realized. Accordingly, it is more preferable to dispose the directly above nozzle 20A than to dispose the directly below nozzle 20B or the intermediate nozzle 20C, and it is preferable to adjust the spray water quantity QA to be the water quantity (for example, a general water quantity) more than other nozzles.
[0085]
Next, advantages and disadvantages of disposing the intermediate nozzle 20C will be described. Since the divided roll portion 102 of the upper roll 10 exists above the intermediate nozzle 20C, the dripping water 32 does not occur in the spray range of the intermediate nozzle 20C. Accordingly, the spray water 21 of the intermediate nozzle 20C also does not interfere with the dripping water 32. On the other hand, since the divided roll portion 102 of the lower roll 10 exists below the intermediate nozzle 20C, the stagnant water 30 occurs in the spray range of the intermediate nozzle 20C. Accordingly, at least a portion of the spray water 21 of the intermediate nozzle 20C may interfere with the stagnant water 30.
[0086]
Therefore, although only the directly above nozzles 20A are disposed, when the cast slab in entirety in width direction cannot be cooled, it is preferable to dispose the intermediate nozzle 20C to cool the cast slab in entirety in width direction. However, when the spray water 21 of the intermediate nozzle 20C interferes with the stagnant water 30, it is preferable to make the spray water quantity qc of the intermediate nozzle 20C be less than the spray water quantity qA of the directly above
- 36 -

nozzle 20A. Accordingly, in the spray range ofthe spray water 21 ofthe intermediate
nozzle 20C, the interference between the spray water 21 of the intermediate nozzle
20C and the stagnant water 30 is suppressed, and the locally forced cooling ofthe cast
slab 3 can be suppressed. - . _
[0087]
Next, advantages and disadvantages of disposing the directly below nozzle 20B will be described. Since the bearing portion 103 ofthe upper roll 10 exists above the directly below nozzle 20B, the dripping water 32 occurs in the spray range ofthe intermediate nozzle 20C. Accordingly, at least a portion ofthe spray water 21 ofthe intermediate nozzle 20C interferes with the dripping water 32. On the other hand, since the divided roll portion 102 ofthe lower roll 10 exists below the directly below nozzle 20B, the stagnant water 30 also occurs in the spray range ofthe intermediate nozzle 20C. Accordingly, at least a portion ofthe spray water 21 ofthe intermediate nozzle 20C also interferes with the stagnant water 30.
[0088]
Therefore, if possible, it is preferable that the directly below nozzle 20B be not disposed. Accordingly, the spray water 21 ofthe directly below nozzle 20B interfering with the stagnant water 30 and the dripping water 32 can be avoided, and thus, it is possible to prevent occurrence ofthe forced cooling ofthe cast slab 3 due to the increase ofthe heat transfer coefficient.
[0089]
However, although the directly above nozzle 20Aand the intermediate nozzle 20C are disposed, when the cast slab in entirety in the width direction cannot be cooled, when the nozzle disposition of previous equipment is used, or the like, the directly . below nozzles 20B is disposed, and thus, the cast slab in entirel^in the width.direction, .
- 37 -

may be cooled. However, it is preferable to make the spray water quantity qe of the directly below nozzle 20B be less than the spray water quantity qA of the directly-above nozzle 20A and the spray water quantity qc of the intermediate nozzle 20C (qA > qc > QB)- Accordingly, in the spray range of the spray water 21 of the directly below nozzle 20B, the interference between the spray water 21 of the directly below nozzle 20B and the stagnant water 30 or the dripping water 32 is suppressed, and the locally forced cooling of the cast slab 3 can be suppressed.
[0090]
Moreover, with respect to the fact that the spray water quantity qs of the directly below nozzle 20B and the spray water quantity qc of the intermediate nozzle 20C is decreased to what extent so as to be less than the spray water quantity qA of the directly above nozzle 20A, an preliminaiy experiment is performed using an actual continuous casting machine, a simulation testing machine, or the like, and the spray water quantities qA, qB> and qc may be appropriately set based on the experiment results.-
[0091]
For example, when the spray water quantity qc of the intermediate nozzle 20C and the spray water quantity qn of the directly below nozzle 20B are decreased considering the interference between the spray water 21 and the stagnant water 30, a relationship between the increase ratio of the heat transfer coefficient due to the interference between the spray water 21 aud the stagnant water 30, and the spray water quantity is measured using a preliminaiy experiment in advance (refer to FIG. 7). In addition, based on the measurement results, the spray water quantities qe and qc of the directly below nozzle 20B and the intermediate nozzle 20C interfering with the stagnant water.30 ma)- be.set to appropriate water quantities less.than.the^pray water ,
- 38 -

quantity QA of the directly above nozzle 20A so as not to generate the locally forced cooling due to the interference of the stagnant water 30.
[0092]
Moreover, when the spray water quantity qe of the directly below nozzle 20B is decreased considering the interference between the spray water 21 and the dripping water 32, a relationship between the increase ratio of the heat transfer coefficient due to the interference between the spray water 21 and the dripping water 32, and the spray water quantity is measured using a preliminary experiment in advance (refer to FIG. 9). In addition, based on the measurement results, the spray water quantity qs of the directly below nozzle 20B interfering with the dripping water 32 may be set to an appropriate water quantit>' less than the spray water quantity qA of the directly above nozzle 20A so as not to generate the locally forced cooling due to the interference of the dripping water 32.
[0093]
Next, a method for cooling the cast slab 3 by the secondary cooling apparatus 7 having the nozzle disposition will be described. The cast slab 3 is cooled by spraying the cooling water from the nozzles 20 disposed between the support rolls 10 adjacent in the transport direction while supporting and transporting the cast slab 3, which is drawn from the lower end of the mold I, along the pass line by the support rolls 10 (non-driven support rolls 11, pinch rolls 12, segment rolls 13, or the like). At this time, it is preferable to spray the cooling water from the intermediate nozzle 20c at the spray water quantity qc (qA > qc) while spraying the cooling water from the directly above nozzle 20A at the spray water quantity qA- On the other hand, the cooling water of the directly below nozzle 20B is not sprayed, or even when the cooling water.ofthe directly-below nozzle is sprayed, the cooling water is sprayed at.,,.
- 39 -

the spray water quantity qe less than qA and qc (qA > qc > QB). Moreover, each of the spray water quantities qA, qc, and qs may be set to an appropriate water quantity according to a width, a temperature, and a sheet threading speed of the cast slab 3, the installation number of the nozzles 20, and a size, a shape, disposition, or the like of the support roll 10.
[0094]
As described above, in the secondary cooling apparatus 7 of the continuous casting machine according to the present embodiment, the disposition of the nozzles 20 and the spray water quantity q are adjusted according to the positions of the bearing portions 103 of the upper and lower support rolls 10 between the support rolls 10 adjacent vertically (in the transport direction). Accordingly, the spray water 21 interfering with the stagnant water 30 and the dripping water 32 is suppressed, and the locally forced cooling of the cast slab 3 can be prevented. Therefore, the cast slab 3 is uniformly cooled in the width direction, solidification uniformity of the non-solidified portion 3b inside the cast slab 3 can be improved, and thus, cracks and center segregation of the cast slab 3 do not occur, and the cast slab 3 having an excellent quality canbe manufactured.
[0095]
\n addition, in the secondary cooling zone 9, the range, to which the nozzle disposition and the flow rate control are applied, may be an arbitrary range if the range includes at the location in which the stagnant water 30 or the dripping water 32 occurs. However, preferably, the range can be applied to first halves of the vertical portion 9A and the bent portion 9B in the pass line of the secondary cooling zone 9. In the first halves of the vertical portion 9A and the bent portion 9B, since the support rolls 10 and JO adjacent in the transport direction are verticaliy disposed orJn.the inclined direction,
- 40 -

the stagnant water 30 or the dripping water 32 easily occurs. Accordingly, by applying the nozzle disposition and the flow rate control to the first halves of the vertical portion 9A and the bent portion 9B, cooling uniformity in the cast slab width direction can be remarkably improved.
[0096]
[2. Second Embodiment]
Next, a roll shape and a nozzle disposition of a secondary cooling apparatus 7A of a continuous casting machine according to a second embodiment of the present invention will be described. The second embodiment is different from the first embodiment in that a two-divided roll is used, and the groove portion of the support roll 10 through which the cooling water can flow down include not only the bearing portion 103 between the divided roll portions 102 adjacent in the cast slab width direction but also a water passing slit which is formed on a circumferential surface of each divided roll portion 102, and other functional configurations of the second embodiment are similar to those of the first embodiment.
[0097]
FIG. U is a front view showing the disposition of the support rolls 10 and the nozzles 20 of the secondary cooling apparatus 7A according to the second embodiment. As shown in FIG. 11, each support roll 10 is configured to have the two-divided roll, and includes two divided roll portions 102A and 102B, and one bearing portion 103 which is provided between two divided roll portions 102A and 102B. Similar to the first embodiment, in the second embodiment, the bearing portions 103, which are provided respectively on the upstream side support roll 10 and the downstream side support roll 10 adjacent in the transport direction, are disposed (are disposed zigzag) to be deviated from each other in the cast slab width direction. In order to realize the ^
- 41 -

zigzag disposition, the roll portions of the two-divided roll are configured to have a relatively long divided roll portion i02A (hereinafter, referred to as a long roll portion 102A) and a relatively short divided roll portion 102B (hereinafter, referred to as a short roil portion 102B).
[0098]
In this way, when the long roll portion 102A and the short roll portion 102B exist in the two-divided roll, a large amount of stagnant water 30 is generated above the long roll portion 102A. Accordingly, in the second embodiment, in order to decrease the stagnant water 30 on the long roll portion 102A, a slit 104 is formed on the circumferential surface of the long roll portion 102Aofeach support roll 10. In the shown example, only one slit 104 is formed on the circumferential surface of the long roll portion 102A. The depth and the width of each slit 104 are approximately the same as the depth and the width of the bearing portion 103, respectively. However, the present invention is not limited to this example, the number of the slits 104 may be 2 or more, and the depth, the width, the disposition, or the like of the slit 104 may be arbitrarily set.
[0099]
In this way, the slit 104 provided on the long roll portion 102A functions as the groove portion (water passing portion) which causes the cooling water to flow down to the downstream side. Accordingly, since the cooling water collected on the long roll portion 102A flows down to the downstream side through the slit 104 of the intermediate portion of the long roll portion 102A, it is possible to prevent a large amount of stagnant water 30 from occurring on the long roll portion i02A.
[0100] -. , . By arranging the support rolls 10 (two-divided roll) including the slit 104 and
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the bearing portion 103 vertically (transport direction), similar to the three-divided roll according to the first embodiment, the cooling waterflows down at two locations of each support roll 10. Moreover, it is preferable that both groove portions (slit 104 and bearing portion 103) be disposed zigzag so that the slit 104 and the bearing portion 103, which are provided on the upstream side support roil 10 and the downstream side support roll 10 adjacent in the transport direction, are deviated from each other in the cast slab width direction. Accordingly, even when the slit 104 is provided.on the two-divided roll, it is possible to uniformly cool the cast slab in the cast slab width direction.
[0101]
In addition, as shown in FIG. 11, similar to the first embodiment, also in the second embodiment, the plurality of nozzles 20 are arranged at an equal interval in the cast slab width direction in the inter-roll region between the upstream side support roll 10 and the downstream side support roil 10 adjacent in the transport direction, and are divided into the directly above nozzles 20A, the directly below nozzles 20B, and the intermediate nozzles 20C according to the positions.
[0102]
The directly above nozzle 20A-is a nozzle which is disposed at a position (first nozzle position) immediately above the bearing portion 103 or the slit 104 of the lower roll 10 (downstream side support roll 10). Specifically, inFlG. 11, the directly above nozzles 20A are disposed at the first nozzle position which is set between the long roll portion 102A provided on the most upstream side support roll 10 and the bearing portion 103 (groove portion) provided on the center support roll 10, and the first nozzle position which is set between the long roll portion 102A provided on the center support roil 10 and the,slit 104 (groove portion) provided on,the most downstream side support.
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roll 10.
The directlybeiow nozzle 20B is a nozzle which is disposed at a position (second nozzle position) immediately below the bearing portion 103 or the slit 104 of the upper roll 10 (upstream side support roll 10).
Specifically, in FIG. 11, the directly below nozzles 20B are disposed at the second nozzle position which is set between the bearing portion 103 (groove portion) provided on the most upstream side support roll 10 and the long roll portion 102A provided on the center support roll 10, and the second nozzle position which is set between the slit 104 provided on the center support roll 10 and the long roll portion 102A provided on the most downstream side support roll 10.
The intermediate nozzle 20C is a nozzle which is disposed at a position (a third nozzle position other than the first nozzle position and the second nozzle position in the inter-roll region) between the divided roll portions 102A and 102B of the upper roll 10, and the divided roll portions 102A and 102B of the lower roll 10. The functions of the directly above nozzle 20A, the directly below nozzle 20B, and.the intermediate nozzle 20C or the spray water quantities are similar to those of the first embodiment, and thus, the detail descriptions are omitted.
[0103]
As described above, according to the second embodiment, tiie slit 104 is provided on the long roll portion 102A of the two-divided roll, and the disposition and the spray water quantities q of the nozzles 20 are adjusted according to the positions of the bearing portion 103 and the slit 104 of the upper roll 10 and the lower roll 10. Accordingly, the effects similar as the first embodiment are obtained, and the cooling uniformity in the cast slab width direction can be improved. Moreover, according to the second embodiment, the stagnant water 30 occurring on the long roll portion 102A-.
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of thetwo-divided roll is decreased by the slit 104, and the interference the spray water 21 from the nozzle 20 and the stagnant water 30 can be suppressed.
[0104]
[3. Third Embodiment]
Next, a roil shape and a nozzle disposition of a secondaiy cooling apparatus 7B of a continuous casting machine according to a third embodiment of the present invention will be described. The third embodiment is different from the first embodiment in that a two-divided roll is used and a plurality of water passing thin-slits are formed on the circumferential surface of the divided roll portions i02 of the support roll 10, and other functional configurations of the third embodiment are similar to those of the first embodiment.
[0105] -
FIG. 12 is a front view showing the disposition of the support rolls 10 and the nozzles 20 of the secondary cooling apparatus 7B according to the third embodiment. As shown in FIG. 12, each support roll 10 is configured to have the two-divided roll, and includes two divided roll portions 102A and 102B, and one bearing portion 103 which is provided between two divided roll portions 102A and I02B. The bearing portions 103, which are provided respectively on the upstream side support roll 10 (upper roil) and the downstream side support roll 10 (lower roll) adjacent in the transport direction, are disposed (are disposed zigzag) to be deviated from each other in the cast slab width direction. In order to realize the zigzag disposition, the roll portions of the two-divided roll are configured to have the long roll portion 102A and the short roll portion 102B.
[Of 06]
.... In the two-divided roll, since the number.of divisions is small, the stagnant
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water 30 easily occurs on the each divided roll portion 102. Particularly, as described above, a large amount of stagnant water 30 occurs on the long roil portion i02A. Accordingly, in the third embodiment, in order to decrease the stagnant water 30 on the long roil portion 102A and the short roll portion 102B, a plurality of thin slits 106 are formed on the circumferential surfaces of the long roll portion 102Aand the short roll portion 102B of each support roll 10. In the shown example, the plurality of thin slits 106 are formed at an equal interval similarly on the circumferential surfaces of the long roll portion 102Aand the short roll portion I02B. The depth and the width of each slit 106 are sufficiently smaller than the depth and the width of the bearing portion 103. However, the present invention is not limited to this example, and the installation number, the depths, the widths, the disposition, or the like of the slits 106 may be arbitrarily set.
[0107]
In this way, the plurality of thin slits 106 provided on the long roll portion
102A and the short roll portion 102B function as the groove portion (water passing
portion) which causes the cooling water to flow down to the downstream side.
Accordingly, since the cooling water flowing down on the long roll portion 102A and
the short roll portion 102B directly flows down (downstream side) through the slits
106, the stagnant water 30 does not occur on the long roll portion I02A and the short
roll portion I02B. In addition, since the cooling water appropriately flows down
from each slit 106, the cooling water does not collectively flow down on the bearing
portion 103. Therefore, the dripping water through the bearing portion 103 is
significantly decreased, and in each support roll 10, minute dripping water 34 which is
uniformly dispersed in the cast slab width direction can be generated.
. . [0108] .. -
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In addition, as shown in FIG. 12, similar to the first embodiment, in the third embodiment, the plurality of nozzles 20 are also arranged at an equal interval in the cast slab width direction in the inter-roll region between the upper roll 10 and the lower roll 10. Since the sprayed cooling water interferes with the minute dripping water 34 flowing down through the slit 106 or the bearing portion 103, all nozzles are divided into the nozzles having the type similar to the directly below nozzle 20B. However, the flow rate of the dripping water 34 is slight, even though the spray water 21 of the directly below nozzle 20B interferes with the dripping water-34, the heat transfer coefficient between the cooling water and the cast slab 3 at the interference position is not greatly increased, and thus, the locally forced cooling as the first embodiment does not occur. Accordingly, even though the directly below nozzle 20B is sprayed at a general flow rate without adjusting the spray water quantity of the directly below nozzle 20B, the uniformity in the cast slab width direction is almost not adversely affected. Of course, the spray water quantity of the directly below nozzle 20B may be smaller than a general water quantity.
[0109]
As described above, according to the third embodiment, the plurality of thin slits 106 are provided on the long roll portion 102A and the short roil portion 1026 of the two-divided roll. Accordingly, similar to the first embodiment, the cooling uniformity in the cast slab width direction can be improved. In addition, according to the third embodiment, occurrence of the stagnant water 30 on the divided roU portions 102 of the two-divided roll can be prevented by each slit 106, and thus, the inference between the spray water 21 from the nozzle 20 and the stagnant water 30 can be suppressed. Moreover, since the dripping water 34 flowing down through the slits . 106 and the bearing portions 103 isminute, there is an advantage that the nozzles 20
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can be freely disposed at arbitraiy horizontal positions without considering the position -of the dripping water 34.
[Example]
[OHO]
Next, examples of the present invention will be described. Moreover, the following examples show test results for demonstrating effects of the present invention, and thus, the present invention is not limited to the following examples.
[0111]
(1) Measurement Result of Cast Slab Surface Temperature by Actual Continuous Casting Test
First, a continuous casting test is performed using the continuous casting machine shown in FIG. 1, a surface temperature of the cast slab 3 in the secondary cooling zone 9 below the mold 1 is measured, and the results will be described. In this test, when a cast slab 3 having a thickness 300 mm x a width 2200 mm was cast at a casting speed of 1.0 m/min, the surface temperature of the cast slab 3 was measured at a position of an approxunately 18 m from a meniscus, using a radiation-type thermometer. The measurement results of the cast slab surface temperature are shown in FIG. 13. FIG. 13 shows the measurement results of the example of the present invention and a comparative example.
[0112]
In the comparative example, the support rolls 10 and the nozzles 20 were disposed as shown in FIG. 10, and the spray water quantities q of all nozzles 20 were set to be the same as one another. As a result, in the comparative example, as shown in FIG. 13, a temperature difference AT' between a center portion and an edge portion in.thecast slab width direction was 100°C or more, and. the cooling uniformity in.the
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cast slab width direction deteriorated. As the reasons, it is assumed because the
comparative example becomes the bearing disposition in which the spray water is
easily collected in the divided roll portion 102 in the vicinity of the center portion in
tlie cast slab width direction, and thus, the interference between stagnant water 30 and
the spray water 21 occurs, and the dripping water 32 from the bearing portion 103 is
collected in the vicinity of the center portion and a large amount of dripping water
occurs, and thus, the spray water of the directly below nozzle 20 interferes with the
dripping water 32. -
[0113]
Accordingly, in the example of the present invention, as shown in FIG. 11, the slits 104 were installed on the support roll 10 so that the stagnant water 30 was not collected, and the spray water quantity of the directly below nozzle 20B positioned at the position interfering with the dripping water 32 from the bearing portion 103 was further decreased than other nozzles 20. As a result, as shown in FIG. 13, in the example, the temperature difference AT between the.center portion and the edge portion in the cast slab width direction was decreased to be an approximately 50°C, and the cooling uniformity in the cast slab width direction was significantly improved. Accordingly, a temperature distribution in the cast slab width direction was uniform, and solidification uniformity and a center segregation-level of the cast slab 3 were improved.
[0114]
(2) Estimation Result of Cast Slab Surface Temperature and Solid Phase Rate by Calculation
Next, a solidified state of the cast slab 3 is simulated using the heat transfer coefficient measured at the test shown in EIG..7, a test for estimating a cast slab surface
. 49 -

temperature and a solid phase rate is performed, and tlie results will be described. In this test, the cast conditions or the conditions in the disposition configuration of the rolls and the nozzles were set to be similar to (1), and the simulation was performed.
FIG. 14A is a distribution view showing the cast slab surface temperature in the comparative example obtained by the present simulation. FIG. 14B is a distribution view showing the cast slab surface temperature in the example of the present invention obtained by the present simulation. FIG. 15A is a distribution view showing the solid phase rate of a center in a cast slab thickness direction in the comparative example obtained by the present simulation. FIG I5B is a distribution view showing the solid phase rate of the center in the cast slab thickness direction in the example of the present invention obtained by the present simulation. Moreover, the solid phase rate when the cast slab 3 was completely non-solidified was set to 0.0, and the solid phase rate when the cast slab 3 was completely solidified was set to 1.0.
[0115]
As shown in FIG. 14A, in the comparative example, mainly in an region A of 5 to 10 m from the meniscus, the cast slab surface temperature is locally decreased due to the interference between the spray water 21, and the stagnant water 30 and the dripping water 32, and it is understood that the temperature in the cast slab width direction is non-uniform. On the other hand, as shown in FIG 14B, in the example of the present invention, the local decrease of the cast slab surface temperature in the region A is not generated, and it is understood that the cooling uniformity in the cast slab width direction is improved. It is considered that the reason is because the inference between the spray water 21, and the stagnant water 30 and the dripping water 32 almost does not occur in the region A in the example, and thus, the local overcooling.of the cast slab.surface can be prevented. .„ . -...-..... . ....
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[0116]
Moreover, as shown in FIG. 15A, in the comparative example, in a region B of 25 m to 30 m from the meniscus, the solidification in the cast slab width direction was non-uniform due to the influence of the cooling non-uniformity in the region A, and the solidification of the center portion in the cast slab width direction was completed in advance. Accordingly, concentrated molten steel wasleft in a solidification delay portion, and the center segregation occurred. On the other hand, as shown in FIG. 15B, in the example of the present invention, the solid phase rate in the region B was uniform in the cast slab width direction, the solidification uniformity was improved, and the center segregation was decreased. It is considered that the reason is because in the example, the cast slab 3 is uniformly cooled in the width direction up to the region B.
[0117]
From the test results described above, according to the present invention, the cooling uniformity in the cast slab width direction can be improved, and thus, it is demonstrated that the solidification uniformity in the cast slab width direction and the center segregation level can be improved.
[0118]
As described above, preferred embodiments of the present invention are
described in details with reference to the accompanying drawings. However, the
present invention is not limited to the embodiments. It is obvious that a person with
ordinary skill in the art of the present invention can conceive various alterations and
modifications within categories of technical ideas described in claims, and it is
understood that the various alterations and modifications are within the technical range
of the present invention. , .. , . ,. ....„..-. . .
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[Brief Description of the Reference Symbols] [0119] i: MOLD
2: MOLTEN METAL 3: CAST SLAB 3A: SOLIDIFIED SHELL 3B: NON-SOLIDIFIED PORTION 4: LADLE 5: TUNDISH 6: DIPPING NOZZLE
7, 7A, 7B: SECONDARY COOLING APPARATUS 8: CAST SLAB CUTTER 9: SECONDARY COOLING ZONE 9A: VERTICAL PORTION 9B: BENT PORTION 9C: HORIZONTAL PORTION 10: SUPPORT ROLL 11: NON-DRIVEN SUPPORT ROLL 12: PINCH ROLL 13: SEGMENT ROLL 14: CAST SLAB 15: TABLE ROLL 20: NOZZLE
20A: DIRECTLY ABOVE NO^LE 20B: DIRECTLY. BELOW NOZZLE -
- 52 -

20C: INTERMEDIATE NOZZLE
2h SPRAY WATER
30: STAGNANT WATER
31: INTERFERENCE RANGE
32, 34: DRIPPING WATER
33: INTERFERENCE RANGE
101: ROLL SHAFT
102: DIVIDED ROLL PORTION
103: BEARING PORTION
104, i06: SLIT
105: GAP
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[Document Type] CLAIMS
[Claim I]
A secondary cooling apparatus of a continuous casting machine, the apparatus comprising:
a plurality of pairs of support rolls which support a cast slab from both sides in a thickness direction of the cast slab in a secondary cooling zone below a mold of the continuous casting machine; and
a plurality of nozzles which are disposed with an interval to one another in the width direction of the cast slab between the support rolls arranged adjacent to each other along a transport direction of the cast slab, and spray cooling water to the cast slab,
wherein each support roll includes:
a roll shaft;
a plurality of roll portions which are provided on the roil shaft and divided in the width direction; and
a groove portion which is provided between the plurality of roll portions and through which the cooling water can flow down,
wherein the groove portions, which are each provided on an upstream side support roll and a downstream side support roll adjacent in the transport direction, are disposed to be deviated from each other in the width direction, and
wherein a first nozzle among the plurality of nozzles is disposed at a first nozzle position which is set between the roll portion provided on the upstream side support roll and the groove portion provided on the downstream side support roll. [Claim 2]
The secondary cooling apparatus of a continuous, casting machine according
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to Claim i,
wherein a second nozzle among the plurality of nozzles is disposed at a second, nozzle position which is set between the groove portion provided on the upstream side support roll and the roll portion provided on the downstream side support roll, and
wherein a water quantity of the cooling water sprayed from the second nozzle is less than a water quantity of the cooling water sprayed from the first nozzle. [Claim 3]
The secondary cooling apparatus of a continuous casting machine according to Claim 2,
wherein a third nozzle among the plurality of nozzles is disposed at a third nozzle position which is set at a position other than the first nozzle position and the second nozzle position between the upstream side support roll and the downstream side support roll, and
wherein a water quantity of the cooling water sprayed from the third nozzle is less than the water quantity of the cooling water sprayed from the first nozzle and is greater than the water quantity of the cooling water sprayed from the second nozzle. [Claim 4]
The secondaiy cooling apparatus of a continuous casting machine according to any one of Clahns 1 to 3,
wherein a bearing portion which supports the roll shaft is provided between the plurality of roll portions of each support roll, and
wherein the groove portion includes the bearing portion. [Claim 5]
. Thesecondary cooling apparatus of a continuous casting-machine according
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to any one of Claims 1 to 3,
wherein the groove portion includes a water passing slit which is formed on a circumferential surface of the support roll. [Claim 6]
A secondary cooling method in which a plurality of pairs of support rolls are provided, which support a cast slab fi"om both sides in a thickness direction of the cast slab in a secondary cooling zone below a mold of a continuous casting machine, and include a plurality of roll portions divided in a width direction of the cast slab and a groove portion which is provided between the plurality of roll portions and through which a cooling water can flow down, and in a situation where the groove portions, which are each provided on an upstream side support roll and a downstream side support roll arranged adjacent to each other along a transport direction of the cast slab, are disposed to be deviated from each other in the width direction, the cast slab transported by the support rolls is cooled, the method comprising:
spraying the cooling water to the cast slab from a first nozzle position between the roll portion provided on the upstream side support roll and the groove portion provided on the downstream side support roll. [Claim 7]
The secondary cooling method according to Claim 6, further comprising:
spraying the cooling water to the cast slab with a water quantity less than a water quantity of the cooling water sprayed from the first nozzle position from a second nozzle position between the groove portion provided on the upstream side support roll and the roll portion provided on the downstream side support roll. [Claims]
The secondary cooling method according to Claim 7, further comprising: .
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spraj'ing the cooling water to the cast slab with a water quantity which is less than the water quantity of the cooling water sprayed from the first nozzle and is greater than the water quantity of the cooling water sprayed from the second nozzle, from a third nozzle position other than the first nozzle position and the second nozzle position between the upstream side support roll and the downstream side support roll.
Dated this April 15,2014
[RANJN A MEHTA-DUTT]
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT[S]
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[Document Type] Abstract
A secondary cooling apparatus of a^continuous casting machine includes a plurality of pairs of support rolls and a plurality of nozzles, each support roll includes a plurality of rolls portions which are divided into a width direction of the cast slab and a groove portion provided bet\veen the roll portions. The groove portions, which are each provided on an upstream side support roll and a downstream side support roll adjacent in a transport direction, are disposed to be deviated from each other in the width direction. A first nozzle among the plurality of nozzles is disposed at a fust nozzle position which is set between the roll portion provided on the upstream side support roll and the groove portion provided on the downstream side support roll.
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