KR20200133804A - Secondary cooling device and secondary cooling method of continuous casting - Google Patents

Abstract

It is a secondary cooling device for continuous casting that cools by spraying coolant onto the surface of the cast piece sent in the casting direction, and the casting between the plurality of rolls and a plurality of rolls arranged side by side in the vertical direction along the casting direction A spray nozzle for spraying the cooling water is provided on one surface, wherein the spray nozzle has a cooling water spray axis of the spray nozzle inclined with respect to the long axis direction of the spray range of the cooling water on the surface of the cast piece, and the spray The long axis of the range rotates upward from the injection nozzle around an axis perpendicular to the cast piece surface, and the center of the injection range is the contact position between the roll above the injection nozzle and the surface of the cast piece , It is located above the intermediate position between the roll and the surface of the cast piece below the contact position.

Description

Secondary cooling device and secondary cooling method of continuous casting

The present invention relates to a secondary cooling device and a secondary cooling method for continuous casting.

Conventionally, a secondary cooling method of continuous casting is known (see, for example, Patent Documents 1 to 3).

In the secondary cooling method of Patent Document 1, the cast piece is cooled by a cooling mechanism as shown in FIG. 9. In Fig. 9, a schematic diagram (A) showing a part of the secondary cooling device of continuous casting, a graph (B) showing the relationship between the casting distance and the water density, and a graph (C) showing the relationship between the casting distance and the surface temperature of the cast piece Is shown.

The secondary cooling device for continuous casting in Patent Document 1 is, as shown in Fig. 9A, between a plurality of rolls 2a, 2b arranged side by side in the vertical direction, and between these rolls 2a, 2b. A jet nozzle 9 is provided for spraying cooling water W onto the cast piece surface 41 of the cast piece 4.

As shown in Fig. 9A, the jet nozzle 9 has a coolant jet axis J1, which is the central axis of the coolant W jetted from the nozzle head 31, on a horizontal plane (a plane perpendicular to the vertical direction) It is provided so as to be parallel to P. In addition, the injection nozzle 9 is provided so that the crossing position Q9 of the cast piece surface 41 and the cooling water injection axis J1 coincides with the contact position 42 and the intermediate position 44 of the contact position 43 . Here, the contact position 42 is a contact position between the roll 2a above the injection nozzle 9 and the surface of the cast piece 41, and the contact position 43 is located below the injection nozzle 9 It is a contact position between the roll 2b and the surface 41 of the cast piece.

With such a configuration, the cooling water W is sprayed onto the horizontally long elliptical spraying range 45 on the cast piece surface 41 with the intermediate position 44 as the center in the vertical direction.

When the cooling water (W) is injected into the spraying range 45, the water density on the surface 41 of the cast piece is the maximum water density at the intermediate position 44, as indicated by the broken line in Fig. 9B. Becomes. In addition, the cooling water W sprayed into the spraying range 45 flows downward under the influence of gravity, and the portion lower than the spraying range 45 on the surface 41 of the cast piece and the roll 2b below it It accumulates as falling water W1 between the outer circumferential surface of.

During cooling of the cast piece 4, a predetermined position on the surface of the cast piece 41 moves downward, and when it approaches the contact position 42 with the roll 2a first contacting, FIG. 9(C) As indicated by the broken line of, when the temperature of the cast piece surface 41 starts to decrease by cooling the roll by contact with the roll 2a, it is separated from the contact position 42 downward by a predetermined distance or more. Keep going down to

Thereafter, the temperature of the cast piece surface 41 is reheated (hereinafter, hereinafter, the temperature of the cast piece surface 41, hereinafter, until the predetermined position on the cast piece surface 41 falls within the spray range 45 of the cooling water W). The reheating between the rolls 2a is raised by "first reheating"), and when it enters the spraying range 45, it continues to descend by spray cooling until it passes therethrough.

And, when the predetermined position on the surface of the cast piece 41 passes through the spraying range 45, the temperature of the surface of the cast piece 41 approaches the contact position 43 with the roll 2b that contacts the second time. Until it rises by reheating (hereinafter, the reheating between the spraying range 45 and the roll 2b below it is referred to as ``second reheating''), and when it approaches the contact position 43, the It continues to descend by cooling the roll by contact with the roll 2b until it is separated from the contact position 43 by a predetermined distance or more.

Thereafter, the cycles of the first reheating, spray cooling, second reheating, and roll cooling described above are repeated with respect to the cast piece surface 41, whereby the entire cast piece 4 is cooled and the temperature gradually decreases.

In Patent Document 1, by using the secondary cooling device as described above and spraying the cooling water onto the surface of the cast piece at a water pressure higher than the general water pressure, the cooling ability of the cast piece is enhanced and the amount of bulging is reduced.

In Patent Document 2, the central axis of the spraying direction of the spraying nozzle is inclined with respect to the central axis of the spraying nozzle, and the spraying direction of the spraying nozzle is rotated in the in-plane direction of the cast piece, so that the cooling water is downstream from the upstream side of continuous casting. Disclosed is a secondary cooling method of continuous casting in which cooling water is inclined in a major axis direction of a spray surface to a cast piece so as to be sprayed toward the side.

In the secondary cooling device of this Patent Document 2, as shown in Figs. 10A and 10B, the cooling water injection axis J1 is rotated with respect to the repair line on the surface of the cast piece, and the casting direction DC (moving direction of the cast piece) After inclining to the upstream side of, the injection range 45 is tilted obliquely downward. In Figs. 10A and 10B, elements corresponding to those in Fig. 9 are denoted by the same reference numerals.

Specifically, in the line of sight of Fig. 10A, first, the cooling water injection axis J1 is inclined at an inclination angle α in the lateral direction of the cast piece 4 with respect to the water line. At this time, the center 450-1 of the injection range 45-1 moves to the center 450-2 of the injection range 45-2. Subsequently, as shown in FIG. 10B, the cooling water injection axis J1 is rotated at a rotation angle β so that the long axis LB-1 of the injection range 45-1 faces obliquely downward. As a result, the long axis LB-1 of the injection range 45-1 moves to the position of LB-3, and the injection range moves from 45-2 to the position of 45-3. However, when the rotation angle β is large, the obliquely lower portion of the cooling range indicated by reference numeral 45-3 is blocked by the lower roll. Therefore, in Patent Document 2, the cooling water injection axis J1 is further inclined in a direction opposite to the inclination angle γ min and the moving direction of the cast piece. As a result, the major axis LB-3 moves to the position of LB-4, and the injection range moves from 45-3 to the position of 45-4.

In this way, the coolant spray axis J1 is inclined obliquely downward on the surface of the cast piece in the line of sight of Fig. 10B, and as a result, the center 450-4 of the spray range 45-4 is brought to its original state ( It is inclined to the lower side, which is more oblique than the code 450-1). With such a configuration, even if the rotation angle β is increased, the coolant is not blocked by the lower roll, and can be sprayed to the lower right to scoop falling water W1 (in FIG. Is spraying towards). As a result, the falling water W1 is discharged toward the side of the width direction of the cast piece, and cooling unevenness in the width direction of the cast piece can be reduced.

Patent Literature 3 discloses that, as shown in Fig. 2, the injection nozzle body between a plurality of rolls arranged side by side in the vertical direction is inclined upward with respect to a horizontal plane, and cooling water is injected obliquely upward.

Japanese Patent Publication No. 2003-285147 Japanese Patent No. 5741874 Japanese Patent Publication No. 2018-1208

By the way, in continuous casting, it is desired to improve the productivity as well as the quality of the cast piece. As one measure for this, it is conceivable to increase the heat transfer coefficient between the cooling water and the surface of the cast piece during spray cooling. For example, as disclosed in Patent Literature 1, when cooling water is sprayed onto the surface of a cast piece at high pressure, the amount of cooling water that contacts the surface of the cast piece per unit time increases, so that the heat transfer coefficient increases and productivity is considered to be improved.

However, in the method of Patent Document 1, new facilities such as an expansion of a pump or a high-pressure type piping are required, resulting in an increase in cost.

In the method of Patent Document 2, it is aimed at reducing the cooling unevenness of the cast piece by sailing and spraying the cooling water from the upstream side to the downstream side of the continuous casting, and no consideration is given to increasing the heat transfer coefficient of the cooling water and the surface of the cast piece. Not.

In the apparatus and method of Patent Document 3, the injection position is adjusted by tilting the injection nozzle body with respect to the horizontal plane. However, in general, since it is preferable that the distance between the rolls is as narrow as possible, the distance between the outer circumferential surface of the roll above the spray nozzle and the outer peripheral surface of the roll below is only about 30 mm to 40 mm, for example. It is not easy to insert the spray nozzle body into such a narrow gap to incline it up and down.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a secondary cooling device for continuous casting and a secondary cooling method that improves productivity without causing an increase in cost.

In order to solve the above problems, the present invention employs the following means.

(1) A first aspect of the present invention is a secondary cooling device for continuous casting, in which cooling water is sprayed onto the surface of the cast piece sent in the casting direction to cool it, and a plurality of secondary cooling devices arranged side by side in the vertical direction along the casting direction A spray nozzle for spraying the cooling water onto the surface of the cast piece between a roll and the plurality of rolls, wherein the spray nozzle has a coolant spray axis of the spray nozzle to spray the coolant on the surface of the cast piece It is inclined with respect to the direction of the major axis of the range, and the major axis of the injection range is rotated upward around an axis line perpendicular to the surface of the cast piece from the injection nozzle, and the center of the injection range is above the injection nozzle. It is located above the contact position between the roll and the surface of the cast piece and an intermediate position between the contact position between the roll and the surface of the cast piece below.

According to the aspect described in the above (1), since the center of the spraying range is made higher than the intermediate position, and the cooling water spraying axis is inclined upwardly obliquely with respect to the repair line of the cast piece surface, In the contact position between the roll and the surface of the cast piece, the injection point of the cooling water can be brought close. Thereby, it is possible to cool the surface of the cast piece facing downward through the contact position before the temperature rises significantly by reheating. Therefore, the cooling effect of the cast piece can be increased more than before and productivity can be improved. In addition, since the cooling effect of the cast piece can be improved without forming a new facility, it does not cause an increase in cost.

(2) In the aspect described in the above (1), in the spray nozzle, the cooling water spray axis is inclined by 30° to 40° with respect to the major axis direction of the spray range of the cooling water on the surface of the cast piece, and the The long axis of the injection range may be provided so as to rotate 5° to 15° upward around an axis line perpendicular to the surface of the cast piece from the injection nozzle.

(3) A second aspect of the present invention is a secondary cooling method of continuous casting, having a step of spraying cooling water onto the surface of a cast piece from a spray nozzle disposed between a plurality of rolls arranged side by side in the vertical direction along the casting direction to cool it. Wherein the cooling water injection axis of the injection nozzle is inclined with respect to the long axis direction of the injection range of the cooling water on the surface of the cast piece, and the long axis of the injection range is perpendicular to the surface of the cast piece from the injection nozzle. It rotates upward around an axis, and the center of the injection range is between the contact position between the roll above the injection nozzle and the surface of the cast piece, and the contact position between the roll and the surface of the cast piece below It is located above the position.

According to the aspect described in the above (3), the same effect as that of the above aspect (1) can be obtained.

According to each of the above aspects of the present invention, it is possible to provide a secondary cooling device for continuous casting and a secondary cooling method for improving productivity without causing an increase in cost.

1 is a side view showing a part of a secondary cooling device for continuous casting according to an embodiment of the present invention, and an enlarged view of a main part thereof.
Fig. 2 is a front view showing an arrangement state of a roll and a jet nozzle in the same embodiment, and an enlarged view of a main part thereof.
3 is a schematic perspective view of an injection nozzle according to the embodiment.
4A is a view showing a state in which the cooling water injection axis of the injection nozzle in the same embodiment is inclined with respect to the long axis direction of the injection range, and is a view when the surface of the cast piece is faced.
Fig. 4B is a perspective view of Fig. 4A.
5A is a view showing a state in which the cooling water spray axis of the spray nozzle in the embodiment is inclined upwardly obliquely with respect to the repair line of the cast piece surface, and is a view when the surface of the cast piece faces.
5B is a perspective view of FIG. 5A.
6 is an explanatory diagram showing a cooling mechanism in the secondary cooling device for continuous casting of the same embodiment, a schematic diagram showing a part of the secondary cooling device for continuous casting (A), and a graph showing the relationship between casting distance and water density (B) and a graph (C) showing the relationship between the casting distance and the surface temperature of the cast piece.
7 is a diagram showing a comparative example for confirming the effect of the present invention, and is a front view showing an arrangement state of a roll and a spray nozzle.
8 is a graph showing secondary cooling simulation results of continuous casting in Examples and Comparative Examples in the same embodiment.
9 is an explanatory diagram showing a cooling mechanism in a conventional secondary cooling device for continuous casting, a schematic diagram showing a part of the secondary cooling device for continuous casting (A), and a graph showing the relationship between the casting distance and the water density (B ), and a graph (C) showing the relationship between the casting distance and the surface temperature of the cast piece.
Fig. 10A is a view for explaining a secondary cooling method using a secondary cooling device for a conventional continuous casting, and is a view when the surface of a cast piece is faced.
Fig. 10B is a diagram showing a state in which the injection range is further moved in Fig. 10A.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In addition, in the case of indicating the direction in the present embodiment, the +X direction, -X direction, +Y direction, -Y direction, +Z direction, and -Z direction of the coordinate axis shown in FIG. 1 are "left" and "right", respectively. "," "before", "after", "top", "bottom".

[Configuration of secondary cooling device for continuous casting]

First, the configuration of the secondary cooling device for continuous casting will be described.

As shown in the upper drawing of FIG. 1, the secondary cooling apparatus 1 of continuous casting is a plurality of rolls 2 arranged side by side in the vertical direction along the casting direction DC (in the lower drawing of FIG. 1, the rolls 2a, 2b)) and a spray nozzle 3 for spraying cooling water W to the surface 41 of the cast piece between the plurality of rolls 2. Each roll 2 and each injection nozzle 3 are arranged side by side also in the front-rear direction, as shown in FIG.

The diameter R of the roll 2 is preferably 100 mm or more and 400 mm or less. The pitch L1 (the distance between the centers C of the rolls 2 adjacent to each other up and down) between the rolls 2 adjacent to each other is 100 mm or more and 450 mm or less. In addition, it is preferable that the distal end of the spray nozzle 3 can be inserted into the gap between the outer peripheral surfaces of the rolls 2 adjacent to each other. Specifically, the gap is 30 mm to 40 mm.

As shown in the lower figure of FIG. 1, the injection nozzle 3 is provided with the nozzle head 31 of a columnar shape or prism shape, for example. And, as shown in the lower figure of FIG. 2, the spray range 46 of the cooling water W sprayed from this nozzle 3 to the surface 41 of a cast piece has an elliptical shape. The direction of the long axis LA of the ellipse shape (hereinafter, simply referred to as the major axis direction) is inclined with respect to the horizontal direction (Y direction), and the center 460 of the injection range 46 (reference numeral 460-3) Side) is located above the contact position 42 and the intermediate position 44 of the contact position 43. Here, the contact position 42 is a contact position between the roll 2a above the injection nozzle 3 and the surface of the cast piece 41, and the contact position 43 is a roll under the injection nozzle 3 It is the contact position between (2b) and the surface 41 of a cast piece. In addition, the cooling water injection axis J1 of the injection nozzle 3 is provided inclined upwardly obliquely with respect to the repair line of the cast piece surface 41. As shown in FIG. 2, the injection nozzle 3 may be provided so that the long-axis direction end part of the injection range 46 adjacent to each other in the front-rear direction (Y direction) may overlap vertically, or may not overlap.

Such a configuration can be realized as follows.

First, as the spray nozzle 3 used in the secondary cooling device of the present embodiment, a two-fluid nozzle having the following configuration can be suitably used, for example, as shown in FIG. 3.

That is, as the spray nozzle 3, as shown in FIG. 3, a nozzle body 11 having a prismatic nozzle head, and a plurality of (a pair of illustrations) formed at the tip end of the nozzle body 11 ( 12, 12', a pair of discharge ports 13 and 13' that open in a long and thin shape in the grooves 12, 12', and a plurality of flow paths 14 and 15 connected to the discharge ports 13 and 13'. , 16) can be adopted. The other end is formed deeper than the one end of the grooves 12 and 12', and the central position of the discharge ports 13 and 13' in the grooves 12 and 12' is the nozzle body ( It is shifted from the axis of 11) and is located on the other end side of the grooves 12 and 12'.

In this injection nozzle 3, the fluid injected from the discharge ports 13 and 13' flows along the discharge walls constituting the grooves 12 and 12'. In addition, since the center of the discharge ports 13 and 13' is located on the other end (deep groove) side of the grooves 12, 12', the fluid from the discharge ports 13, 13' is on the deep groove side. Flows in more. Therefore, the injection amount from the other end (thick portion or deep groove portion of the discharge wall) can be increased while regulating the injection amount from one end (thin portion or shallow groove portion of the discharge wall). As a result, cooling water (gas-liquid mixing mist) is mainly sprayed into the oblique front area of the nozzle tip. Therefore, according to this injection nozzle 3, as shown in the lower figure of FIG. 2, the shape of the injection range 46 on the surface 41 of a cast piece can be made into an eccentric elliptical shape. More specifically, the center 460-1 of the spraying range 46-1 moves to 460-3 by intensively spraying the coolant to the oblique front area of the nozzle tip. That is, as shown by the solid line in the lower figure of FIG. 2, the spraying range 46-3 of the cooling water sprayed from the tip of the nozzle has an eccentric elliptical shape.

Further, the grooves 12 and 12' may be inclined by 3° to 40° based on a direction orthogonal to the axial center of the nozzle body 11.

That is, in at least one of the grooves 12 and 12', a line connecting the lower end of the bottom of one end (shallow groove) and the lower end of the bottom of the other end (deep groove) is the nozzle body 11 It may be inclined about 3° to 40° based on a direction orthogonal to the axis. The flow rate distribution (distribution of the injection amount from each end side) to each end portion of the grooves 12 and 12' can be adjusted by this inclination angle.

As described above, in the spray nozzle 3, one end of the grooves 12 and 12' (injection openings) for spraying the cooling water W is formed deeper than the other end, and thus Figs. 4A and 4B As shown in FIG. 1, the cooling water injection axis J1 indicated by a solid line is inclined at an inclination angle α1 with respect to the axis 310 of the nozzle head 31. Specifically, the coolant jetting axis J1 of the jetting nozzle 3 is inclined at an inclination angle α1 with respect to the long axis direction of the jetting range 46 of the coolant W on the cast piece surface 41. Further, the axis 310 is a line from the nozzle head 31 to the cast piece surface 41. In the case where the coolant spray axis J1 is not inclined with respect to the long axis direction of the spray range 46, and the long axis direction of the spray range 46 is rotated around the axis 310 with respect to the horizontal direction, the lower view of FIG. As indicated by the two-dot chain line, the crossing position of the axis 310 of the nozzle head 31 and the surface of the cast piece 41 coincides with the center 460-1 of the spray range 46-1, so that the axis 310 Cooling water (W) is sprayed in a symmetrical pattern centered on. In contrast, when the coolant spraying axis J1 is inclined with respect to the long axis direction of the spraying range 46, as shown by the solid line in FIG. 4B, the crossing position of the axis 310 and the cast surface 41 is the spraying range Since it does not coincide with the center 460-2 of (46-2), the cooling water W is sprayed in an asymmetrical pattern centered on the axis line 310. In this embodiment, the cooling water W is sprayed on the surface 41 of a cast piece in this way in an asymmetric pattern.

In addition, as shown in FIG. 4B, it is preferable that the inclination angle α1 of the injection range 46 of the cooling water injection axis J1 with respect to the long axis direction is inclined by 30° to 40°. As for the expansion angle of the cooling water W injected from the spray nozzle 3 in the long axis direction, it is preferable that the narrow angle side angle α2 is more than -90° and less than 90°, and the wide angle side angle α3 is the inclination angle α1 or more and 95° or less. In addition, the narrow angle side angle α2 is the angle of the coolant W that is expanded to the narrow angle side (in FIG. 4B, the left side of the paper based on the axis line 310) with respect to the axis line 310, and the wide angle side angle α3 is the axis line. It is the angle of the cooling water W which expands to the wide-angle side (in FIG. 4B, the right side of the paper based on the axis 310) based on 310.

Then, from the state that the nozzle head 31 of the spray nozzle 3 is positioned in the middle of the upper and lower rolls 2a, 2b, the axis 310 is parallel to the water line of the cast piece surface 41, By rotating the long axis of the spray range 46-2 of the cooling water W on the surface 41 upwardly around the axis 310 at a rotation angle β, as indicated by the solid lines in FIGS. 5A and 5B, The long axis LA of the injection range 46-2 faces obliquely upward, as indicated by the symbol LA-1. As a result, the cooling water jetting axis J1 is inclined upwardly obliquely with respect to the repair line of the cast piece surface 41, and the jetting range moves from the reference numeral 46-2 to the position 46-3. With such a configuration, as shown in Fig. 2, the wide-angle side of the injection range 46 in the long axis direction can be inclined upwardly obliquely with respect to the horizontal direction. In addition, the center 460-3 of the spraying range 46-3 is positioned above the intermediate position 44, and the cooling water spraying axis J1 of the spraying nozzle 3 is a repair of the cast piece surface 41 It can be inclined upwards obliquely to

As a result, the coolant W is sprayed into the spraying range 46 with a position above the intermediate position 44 as the center in the vertical direction in the line of sight of Fig. 6, as shown in Fig. 6A. . That is, as indicated by the solid line in Fig. 6B, the cooling water W is higher than the conventional spraying range 45 in Fig. 9A (indicated by a broken line in Fig. 6B). It is injected into the shifted injection range 46. In addition, the thickness (height) in the vertical direction (Z direction) of the spraying range 46 when viewed from the line of sight (+Y direction side) of FIG. 6 is that of the conventional spraying range 45 of FIG. 9A. It becomes thicker than the vertical direction (Z direction). In addition, by inclining the cooling water injection axis J1 obliquely upward, the cooling water injection axis J1 is not inclined with respect to the long axis direction of the injection range 46, as shown by the double-dashed line in the lower drawing of FIG. Compared with the configuration in which the cooling water W is sprayed in a symmetrical pattern centered on (310), the amount of spraying in the oblique upward direction can be increased. In addition, the upper end position 461 of the injection range 46 on the cast piece surface 41 can be positioned above the upper end position of the injection range 45 on the conventional cast piece surface 41. .

In addition, it is preferable that the rotation angle β rotating upward around the axis 310 of the spray nozzle 3 (injection range 46) is inclined by 5° to 15°.

The distance M from the middle position 44 of the pair of rolls 2 to the center 460-3 of the injection range 46 in the vertical direction (Z direction) (refer to the lower drawing in Fig. 2) is , More than 0 mm (L1/2) mm or less is preferable.

The distance L2 (X direction) from the tip of the nozzle head 31 of the spray nozzle 3 to the surface 41 of the cast piece (refer to the lower drawing in Fig. 1) is preferably 50 mm or more and 450 mm or less.

The injection range 46 may or may not include the intermediate position 44 of the surface 41 of the cast piece. The distance L3 from the upper end position 461 of the injection range 46 to the contact position 42 with the upper roll 2a on the cast piece surface 41 (refer to the lower drawing in Fig. 1) is, 0 mm or more and 200 mm or less are preferable. The cooling water W may be sprayed so as to contact the upper roll 2a, but it is preferable not to contact it. For example, when the diameter R of the roll 2 is 250 mm, the pitch L1 of the roll 2 is 290 mm, and the distance L2 from the tip of the nozzle head 31 to the surface 41 of the cast piece is 80 mm, the distance L3 is It is preferably about 45mm.

The intersecting position of the axis 310 of the injection nozzle 3 and the surface of the cast piece 41 may or may not overlap with the intermediate position 44.

As shown in FIG. 2, the inclination direction of the long axis LA of the injection range 46 may be alternately different for each row in the width direction of the cast piece 4 or may be the same, or in one row. You may make it symmetric with the center of 4) width direction as a boundary.

[Action of secondary cooling device of continuous casting]

Next, the operation of the secondary cooling device 1 of continuous casting will be described. In the secondary cooling method of continuous casting according to the embodiment, the cast piece is cooled by a cooling mechanism as shown in FIG. 6. 6 is a schematic diagram (A) showing a part of the secondary cooling device of continuous casting, a graph (B) showing the relationship between the casting distance and the water density, and a graph (C) showing the relationship between the casting distance and the surface temperature of the cast piece. Is shown. In addition, below, the case where the upper roll 2a in FIG. 6(A) is the first roll 2 of the secondary cooling device 1 is demonstrated.

When the cast piece 4 is cooled, when a predetermined position on the cast piece surface 41 approaches the contact position 42 with the roll 2a initially in contact, the solid line in Fig. 6C As shown, the temperature of the cast piece surface 41 starts to decrease by cooling the roll due to contact with the roll 2a, and continues to decrease from the contact position 42 downward by a predetermined distance or more. Goes.

At this time, the effect value (temperature difference immediately after roll cooling of this embodiment and the conventional structure) after roll cooling by the roll 2a which comes into contact with the first time (DELTA)Tr1 becomes 0 degreeC.

After that, the temperature of the cast piece surface 41 rises by the first reheat until the predetermined position on the cast piece surface 41 enters the injection range 46, and when it enters the injection range 46, there Continue descending by spray cooling until passing through.

At this time, the injection range 46 indicated by the solid line in FIG. 6B shifts upward as viewed from the line of sight in FIG. 6 than the conventional injection range 45 indicated by the broken line in FIG. ) Thickened. Therefore, the first recuperation period indicated by the solid line in Fig. 6C is shorter than the conventional configuration indicated by the broken line in the figure, and spray cooling starts earlier than the conventional configuration. That is, before the temperature of the cast piece surface 41 is significantly increased by reheating, it can be cooled. For this reason, compared with the conventional configuration, the amount of recuperation is reduced, the temperature of the surface 41 at the start of spray cooling is lowered, and the heat transfer coefficient at the time of spray cooling is increased. As a result, the cooling efficiency E1 becomes higher than the conventional constitutive cooling efficiency E9, and the cast piece surface 41 is cooled to a lower temperature by spray cooling. In addition, since the cooling water injection axis J1 is inclined to an oblique upper side and the injection amount to an oblique upper direction is increased, the amount of recuperation in the first reheat period can be further reduced, and the heat transfer coefficient during spray cooling is further reduced. You can make it big.

In addition, when the predetermined position on the cast piece surface 41 passes within the spray range 46, the temperature of the cast piece surface 41 increases due to the second reheat, but the temperature at the start of the second reheat is the conventional configuration. Since it is lower than, the temperature at the start of cooling by the roll 2b that comes into contact with the second time is also lowered, and the effect value ΔTr2 after the roll cooling by the roll 2b becomes larger than 0°C. After that, by repeating the cycles of the first reheating, spray cooling, second reheating, and roll cooling described above, the temperature of the cast piece 4 is gradually lowered and cooled.

In this cooling process, since the effective value after roll cooling gradually increases as it goes downstream in the casting direction, the cooling time of the cast piece is shortened compared to the conventional configuration.

[Effect of this embodiment]

According to this embodiment, the following effects are obtained.

Since the center of the spraying range 46 is set above the intermediate position 44, and the cooling water spraying axis J1 is inclined upwardly obliquely with respect to the repair line of the cast piece surface 41, the spraying nozzle ( The injection destination of the cooling water W can be brought close to the contact position 42 between the roll 2a above 3) and the surface 41 of the cast piece. Thereby, it is possible to cool the cast piece surface 41 facing downward through the contact position 42 before the temperature rises significantly by reheating. Therefore, the cooling effect of the cast piece 4 can be improved more than before, and productivity can be improved. Moreover, since the cooling effect of the cast piece 4 can be improved without providing a new facility, it does not cause an increase in cost.

Therefore, according to the secondary cooling device and the secondary cooling method for continuous casting of the present embodiment, it is possible to improve productivity without causing an increase in cost.

[Modified example]

In addition, the present invention is not limited only to the above embodiments, and various improvements and design changes can be made within the scope not departing from the gist of the present invention, and in addition, specific procedures and structures in the implementation of the present invention, etc. It is good also considering other structures etc. within the range which can achieve the object of this invention.

For example, the spray nozzle 3 in which the cooling water spray axis J1 is not inclined with respect to the long axis direction of the spray range 46 may be used. In this case, by disposing the distal end of the spray nozzle 3 so as to be closer to the cast piece surface 41 than at the position of Fig. 6A and positioned above it, as shown by the double-dashed line in the lower drawing of Fig. , The cross position of the axis 310 of the nozzle head 31 and the surface 41 of the cast piece coincides with the center 460 of the injection range 46. In addition, the long axis of the injection range 46 rotates around the axis 310 which is a line from the injection nozzle 3 to the surface of the cast piece 41, and the center 460 of the injection range 46 is at an intermediate position ( 44).

Even in such a configuration, compared with the conventional configuration, the spraying range 46 of the cooling water W can be shifted upward, and it can be thickened in the vertical direction (Z direction), and the productivity is not increased. I can plan improvement.

As the spray nozzle 3, a single fluid nozzle may be used.

Example

Next, the present invention will be described in more detail by examples, but the present invention is not limited by these examples.

A simulation for verifying the effect of the present invention will be described.

As parameters common to Examples and Comparative Examples, the following settings were made.

Roll diameter R: 150mm or more and 360mm or less

Roll pitch L1: 190mm or more and 430mm or less

Distance L2 from the tip of the spray nozzle to the surface of the cast piece: 80 mm or more and 430 mm or less

Distance L3 from the top position of the injection range to the contact position with the upper roll on the surface of the cast piece: more than 0 mm (L1/2) mm or less

Spray quantity: 8L/min or more and 80L/min or less per nozzle

Number of nozzles in the width direction per roll: 1 to 16

Casting speed: 2.0m/min

Carbon content in molten steel: 0.04%

Cast piece width: 1500mm

Cast plate thickness: 250mm

In addition, the arrangement state of the roll 2 and the spray nozzle 3 in the example is set as shown in Fig. 2, and the arrangement state of the roll 2 and the spray nozzle 9 in the comparative example Was set as shown in FIG. 7. In Examples and Comparative Examples, ``the inclination angle α1 of the cooling water injection axis J1 with respect to the long axis direction of the injection range 46'', ``the narrow angle angle α2 of the cooling water W relative to the axis 310'' , "Wide angle α3 of the coolant W with respect to the axis 310", "Rotation angle β of the spray nozzles 3 and 9 (injection range 46) rotated upward around the axis 310" ", "the distance M from the middle position 44 of the pair of rolls 2 to the center 460 of the injection range 46 in the vertical direction" is shown in Table 1 below.

In addition, in the comparative example, the cooling water injection axis J1 is not inclined with respect to the long axis direction of the injection range 46, and the intersection position of the axis 910 of the nozzle head 91 and the surface of the cast piece 41 is the injection range. A spray nozzle 9 coinciding with the center 460 of 46 was used. Since the expansion angle in the long axis direction of the coolant W sprayed from the spray nozzle 9 is the same on both sides (left and right sides) in the major axis direction with respect to the axis line 910, in Table 1, the angle of the sum of the left and right sides Represents.

And the secondary cooling of continuous casting was simulated. 8 is an example of a result showing a change in surface temperature of a cast piece in a numerical range shown in Table 1. FIG.

As shown in Fig. 8, the effect value after roll cooling due to contact with the first roll (temperature difference immediately after roll cooling in Examples and Comparative Examples) ΔTr1 became 0°C, but the first reheat period after roll cooling is indicated by a solid line. The example was shorter than the comparative example indicated by the broken line, and the reheat amount of the example could be reduced by 7°C compared to the reheat amount of the comparative example (indicated by "ΔTa" in FIG.

In addition, the drop temperature ΔTsc due to spray cooling in the comparative example is 150°C, the drop temperature ΔTsp in the example is 176°C, and the effect value immediately after spray cooling (the temperature difference between the examples and the comparative example immediately after spray cooling) ΔTb1 became 33°C.

In addition, the effect values ΔTr2 and ΔTr3 after roll cooling by contact with the second and third rolls became 14° C. and 25° C., and the effect values after roll cooling gradually increased as they went downstream in the casting direction. In addition, the effect values ΔTb2 and ΔTb3 immediately after the second and third spray cooling became 49°C and 59°C, and after that, as they went downstream in the casting direction, the effect values immediately after spray cooling gradually increased.

As a result, it was confirmed that the cooling time of the cast piece was shortened by 0.3 min in the Example compared with the Comparative Example.

According to the present invention, it is possible to provide a secondary cooling device for continuous casting and a secondary cooling method for improving productivity without causing an increase in cost. Therefore, the possibility of industrial use is great.

One… Secondary cooling system
2, 2a, 2b... role
3… Spray nozzle
4… Casting
41... Cast surface
42, 43... Contact location
44... Middle position
46... Injection range
460... center
J1... Coolant spray axis
W… cooling water

Claims (3)

It is a secondary cooling device of continuous casting that cools by spraying cooling water on the surface of the cast piece sent in the casting direction,
A plurality of rolls arranged side by side in the vertical direction according to the casting direction,
A spray nozzle for spraying the cooling water on the surface of the cast piece between the plurality of rolls
And,
The spray nozzle,
The cooling water injection axis of the injection nozzle is inclined with respect to the long axis direction of the injection range of the cooling water on the surface of the cast piece,
The long axis of the injection range rotates upward from the injection nozzle around an axis perpendicular to the surface of the cast piece,
The center of the injection range is positioned above the intermediate position between the contact position between the roll and the surface of the cast piece above the injection nozzle and the contact position between the roll and the surface of the cast piece below the injection nozzle.
A secondary cooling device for continuous casting, characterized in that it is provided. The method of claim 1, wherein the spray nozzle,
The cooling water injection axis is inclined by 30° to 40° with respect to the long axis direction of the injection range of the cooling water on the surface of the cast piece,
The long axis of the injection range rotates 5° to 15° upward around an axis line perpendicular to the surface of the cast piece from the injection nozzle,
A secondary cooling device for continuous casting, characterized in that it is provided. It is a secondary cooling method of continuous casting, having a step of spraying cooling water on the surface of a cast piece from a spray nozzle disposed between a plurality of rolls arranged side by side in the vertical direction along the casting direction, and cooling it,
The cooling water injection axis of the injection nozzle is inclined with respect to the long axis direction of the injection range of the cooling water on the surface of the cast piece,
The long axis of the injection range rotates upward from the injection nozzle around an axis perpendicular to the surface of the cast piece,
The center of the injection range is located above the intermediate position between the contact position between the roll and the surface of the cast piece above the injection nozzle, and the contact position between the roll and the surface of the cast piece below.
It characterized in that, the secondary cooling method of continuous casting.

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