Title of the invention: Secondary cooling device and secondary cooling method for continuous casting
Technical field
[0001]
　The present invention relates to a continuous casting secondary cooling device and a secondary cooling method.
Background technology
[0002]
　Conventionally, a secondary cooling method for continuous casting is known (see, for example, Patent Documents 1 to 3).
　In the secondary cooling method of Patent Document 1, the slab is cooled by the cooling mechanism as shown in FIG. FIG. 9 shows a schematic view (A) showing a part of the secondary cooling device for continuous casting, a graph (B) showing the relationship between the casting distance and the water content density, and the relationship between the casting distance and the slab surface temperature. The graph (C) is shown.
[0003]
　As shown in FIG. 9A, the secondary cooling device for continuous casting in Patent Document 1 includes a plurality of rolls 2a and 2b arranged side by side in the vertical direction, and slabs 4 from between the rolls 2a and 2b. It is provided with an injection nozzle 9 that injects cooling water W onto the slab surface 41.
　As shown in FIG. 9A, in the injection nozzle 9, the cooling water injection axis J1 which is the central axis of the cooling water W injected from the nozzle head 31 is parallel to the horizontal plane (plane perpendicular to the vertical direction) P. It is provided as follows. Further, the injection nozzle 9 is provided so that the intersection position Q9 between the slab surface 41 and the cooling water injection axis J1 coincides with the contact position 42 and the intermediate position 44 between the contact positions 43. Here, the contact position 42 is the contact position between the roll 2a above the injection nozzle 9 and the slab surface 41, and the contact position 43 is the contact position between the roll 2b and the slab below the injection nozzle 9. This is the contact position with the surface 41.
[0004]
　With such a configuration, the cooling water W is sprayed onto the slab surface 41 into a horizontally long elliptical spraying range 45 centered at the intermediate position 44 in the vertical direction.
　When the cooling water W is sprayed into the spraying range 45, the water density on the slab surface 41 becomes maximum at the intermediate position 44, as shown by the broken line in FIG. 9B. Further, the cooling water W sprayed into the spraying range 45 flows downward under the influence of gravity, and is between a portion of the slab surface 41 below the spraying range 45 and the outer peripheral surface of the roll 2b below. , It collects as dripping water W1.
[0005]
　When the slab 4 is cooled, the predetermined position on the slab surface 41 moves downward, and when it approaches the contact position 42 with the roll 2a that comes into contact first, the casting is performed as shown by the broken line in FIG. 9C. The temperature of the one surface 41 begins to decrease due to roll cooling due to contact with the roll 2a, and continues to decrease from the contact position 42 downward until it is separated by a predetermined distance or more.
　After that, until the predetermined position on the slab surface 41 falls within the spraying range 45 of the cooling water W, the temperature of the slab surface 41 is reheated (hereinafter, between the spraying range and the roll 2a above the spraying range). The reheat of the above is referred to as "first reheat"), and when it enters the spraying range 45, it continues to decrease by spray cooling until it passes there.
　Then, when the predetermined position on the slab surface 41 passes through the spraying range 45, the temperature of the slab surface 41 is reheated (hereinafter, spraying range) until it approaches the contact position 43 with the roll 2b that comes into second contact. The reheat between 45 and the roll 2b below it is called "second reheat"), and when it approaches the contact position 43, it and the roll 2b until it is separated from the contact position 43 by a predetermined distance or more. Continues to fall due to roll cooling due to contact.
　After that, the cycle of the first reheating, the spray cooling, the second reheating, and the roll cooling described above is repeated with respect to the slab surface 41, so that the entire slab 4 is cooled and the temperature is gradually lowered.
[0006]
　In Patent Document 1, the secondary cooling device as described above is used, and the cooling water is sprayed on the slab surface at a water pressure higher than the general water pressure to enhance the slab cooling capacity and reduce the bulging amount. ing.
[0007]
　In Patent Document 2, the central axis of the injection direction of the injection nozzle is inclined with respect to the central axis of the injection nozzle, and the injection direction of the injection nozzle is rotated in the in-plane direction of the slab, so that the cooling water is continuously cast. A secondary cooling method for continuous casting is disclosed in which the longitudinal direction of the injection surface of the cooling water to the slab is tilted so that the cooling water is injected from the upstream side to the downstream side.
　In the secondary cooling device of Patent Document 2, as shown in FIGS. 10A and 10B, the cooling water injection axis J1 is rotated with respect to the perpendicular line on the surface of the slab, and is upstream in the casting direction DC (movement direction of the slab). After tilting to the side, the spraying range 45 is tilted diagonally downward. The elements corresponding to those in FIGS. 9A and 10B are designated by the same reference numerals.
　Specifically, in the line of sight of FIG. 10A, first, the cooling water injection axis J1 is inclined in the lateral direction of the slab 4 with respect to the vertical line at an inclination angle α. At this time, the center 450-1 of the spray range 45-1 moves to the center 450-2 of the spray 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 spraying range 45-1 faces diagonally downward. As a result, the long axis LB-1 of the spraying range 45-1 moves to the position of reference numeral LB-3, and the spraying range moves from the position of reference numeral 45-2 to the position of reference numeral 45-3. However, when the rotation angle β is large, the diagonally lower portion of the cooling range shown 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 by an inclination angle of γ in a direction opposite to the moving direction of the slab. As a result, the long axis LB-3 moves to the position of reference numeral LB-4, and the spraying range moves from reference numeral 45-3 to the position of reference numeral 45-4.
　In this way, the cooling water injection axis J1 is tilted diagonally downward on the slab surface in the line of sight of FIG. 10B, and as a result, the center 450-4 of the spray range 45-4 is in the original state (reference numeral 450-1). ) And tilt it diagonally downward. With such a configuration, the cooling water can be injected in the lower right direction to scrape out the dripping water W1 without being blocked by the lower roll even if the rotation angle β is increased (in FIG. 10B, the cooling water is the lower right of the paper surface). Is being sprayed towards). As a result, the dripping water W1 is discharged toward the side in the width direction of the slab, and the cooling unevenness in the width direction of the slab can be reduced.
[0008]
　In Patent Document 3, as shown in FIG. 2, the injection nozzle main body between a plurality of rolls arranged side by side in the vertical direction is inclined upward with respect to the horizontal plane, and the cooling water is obliquely upward. Is disclosed to inject.
Prior art literature
Patent documents
[0009]
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-285147
Patent Document 2: Japanese Patent
Application Laid-Open No. 5741874 Patent Document 3: Japanese Patent Application Laid-Open No. 2018-1208
Outline of the invention
Problems to be solved by the invention
[0010]
　By the way, in continuous casting, it is desired to improve the productivity as well as the quality of the slab, and one measure for this is to increase the heat transfer coefficient between the cooling water and the surface of the slab during spray cooling. For example, as disclosed in Patent Document 1, if cooling water is sprayed on the slab surface at high pressure, the amount of cooling water that comes into contact with the slab surface increases per unit time, so that the heat transfer coefficient increases and productivity increases. Is also expected to improve.
　However, the method of Patent Document 1 requires new equipment such as an additional pump and high-pressure piping, which increases the cost.
　The method of Patent Document 2 aims to reduce the cooling unevenness of the slab by injecting the cooling water from the upstream side to the downstream side of the continuous casting, and aims at reducing the cooling unevenness of the slab. No consideration is given to increasing the heat transfer coefficient with.
　In the apparatus and method of Patent Document 3, the injection position is adjusted by inclining the injection nozzle body with respect to the horizontal plane. However, in general, it is preferable that the distance between the rolls is as narrow as possible, so that the distance between the outer peripheral surface of the roll above the injection nozzle and the outer peripheral surface of the roll below is, for example, only about 30 mm to 40 mm. It is not easy to insert the injection nozzle body into such a narrow gap and further tilt it up and down.
[0011]
　The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a continuous casting secondary cooling device and a secondary cooling method capable of improving productivity without causing an increase in cost.
Means to solve problems
[0012]
　In order to solve the above problems, the present invention employs the following means.
(1) The first aspect of the present invention is a continuous casting secondary cooling device that injects cooling water onto the slab surface of a slab sent in the casting direction to cool the slab, and is up and down along the casting direction. A plurality of rolls arranged side by side in a direction and an injection nozzle for injecting the cooling water onto the surface of the slab from between the plurality of rolls are provided, and the injection nozzle is the cooling water injection axis of the injection nozzle. Is inclined with respect to the long axis direction of the cooling water spraying range on the slab surface, and the long axis of the spraying range rotates upward around an axis which is a perpendicular line from the injection nozzle to the slab surface. However, the center of the spraying range is more than the intermediate position between the contact position between the roll and the slab surface above the injection nozzle and the contact position between the roll and the slab surface below. It is located above.
[0013]
　According to the aspect described in (1) above, the center of the spraying range is set above the intermediate position, and the cooling water injection axis is inclined diagonally upward with respect to the vertical line on the slab surface. Therefore, the spraying destination of the cooling water can be brought closer to the contact position between the roll and the slab surface above the injection nozzle. As a result, the surface of the slab that goes downward through the contact position can be cooled before the temperature rises significantly due to the reheat. Therefore, the cooling effect of the slab can be enhanced as compared with the conventional case, and the productivity can be improved. Moreover, since the cooling effect of the slab can be enhanced without installing new equipment, the cost does not increase.
[0014]
(2) In the embodiment described in (1) above, in the injection nozzle, the cooling water injection axis is inclined by 30 ° to 40 ° with respect to the long axis direction of the cooling water spraying range on the slab surface. The long axis of the spraying range may be provided so as to rotate upward by 5 ° to 15 ° around an axis that is a perpendicular line from the injection nozzle to the surface of the slab.
[0015]
(3) A second aspect of the present invention includes a step of injecting cooling water onto the surface of the slab from an injection nozzle arranged between a plurality of rolls arranged side by side in the vertical direction along the casting direction to cool the slab. In the secondary cooling method of continuous casting, the cooling water injection axis of the injection nozzle is inclined with respect to the long axis direction of the cooling water spraying range on the slab surface, and the long axis of the spraying range is , Rotates upward around the axis that is a perpendicular line from the injection nozzle to the surface of the slab, and the center of the spray range is below the contact position between the roll and the surface of the slab above the injection nozzle. It is located above the intermediate position between the roll and the contact position between the slab surfaces.
[0016]
　According to the aspect described in (3) above, the same action and effect as in the aspect (1) above can be obtained.
The invention's effect
[0017]
　According to each of the above aspects of the present invention, it is possible to provide a continuous casting secondary cooling device and a secondary cooling method that can improve productivity without causing an increase in cost.
A brief description of the drawing
[0018]
FIG. 1 is a side view showing a part of a continuous casting secondary cooling device 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 an injection nozzle in the same embodiment, and an enlarged view of a main part thereof.
FIG. 3 is a schematic perspective view of an injection nozzle according to the same embodiment.
FIG. 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 spray range, and is a view in which the surface of the slab is viewed from the opposite side.
FIG. 4B is a perspective view of FIG. 4A.
FIG. 5A is a view showing a state in which the cooling water injection axis of the injection nozzle in the same embodiment is inclined diagonally upward with respect to the perpendicular line of the slab surface, and is a view in which the slab surface is viewed from the opposite side.
5B is a perspective view of FIG. 5A.
FIG. 6 is an explanatory diagram showing a cooling mechanism in the secondary cooling device for continuous casting according to the same embodiment, and is a schematic view (A) showing a part of the secondary cooling device for continuous casting, with casting distance and water density. (B) and a graph (C) showing the relationship between the casting distance and the surface temperature of the slab.
FIG. 7 is a view 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 an injection nozzle.
FIG. 8 is a graph showing the simulation results of secondary cooling of continuous casting in the example in the same embodiment and the comparative example.
FIG. 9 is an explanatory diagram showing a cooling mechanism in a conventional secondary cooling device for continuous casting, which is a schematic view (A) showing a part of the secondary cooling device for continuous casting, and a relationship between a casting distance and a water content density. (B) and a graph (C) showing the relationship between the casting distance and the surface temperature of the slab.
[Fig. 10A] Fig. 10A is a diagram for explaining a secondary cooling method using a conventional continuous casting secondary cooling device, and is a diagram in which the surfaces of slabs are viewed from each other.
FIG. 10B is a diagram showing a state in which the spraying range is further moved in FIG. 10A.
Mode for carrying out the invention
[0019]
　Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
　When the direction is represented in the present embodiment, the + X direction, the −X direction, the + Y direction, the −Y direction, the + Z direction, and the −Z direction of the coordinate axes shown in FIG. 1 are “left”, “right”, and “front”, respectively. , "After," "above," and "below."
[0020]
[Structure of a secondary cooling device for
　continuous casting ] First, a configuration of a secondary cooling device for continuous casting will be described.
　As shown in the upper part of FIG. 1, the secondary cooling device 1 for continuous casting includes a plurality of rolls 2 (rolls 2a and 2b in the lower part of FIG. 1) arranged side by side in the vertical direction along the casting direction DC. A jet nozzle 3 for injecting cooling water W onto the slab surface 41 from between the plurality of rolls 2 is provided. As shown in FIG. 2, each roll 2 and each injection nozzle 3 are arranged side by side in the front-rear direction.
　The diameter R of the roll 2 is preferably 100 mm or more and 400 mm or less. The pitch L1 between the rolls 2 vertically adjacent to each other (distance between the centers C of the rolls 2 vertically adjacent to each other) is 100 mm or more and 450 mm or less. Further, it is preferable that the tip portion of the injection nozzle 3 can be inserted into the gap between the outer peripheral surfaces of the rolls 2 which are vertically adjacent to each other. Specifically, the gap is 30 mm to 40 mm.
[0021]
　As shown in the lower part of FIG. 1, the injection nozzle 3 includes, for example, a cylindrical or prismatic nozzle head 31. The spraying range 46 of the cooling water W sprayed from the nozzle 3 onto the slab surface 41 has an elliptical shape as shown in the lower figure of FIG. The direction of this elliptical long axis LA (hereinafter, may be simply referred to as the long axis direction) is inclined with respect to the horizontal direction (Y direction), and the center 460 of the spraying range 46 (reference numeral 460-3). Is located above the contact position 42 and the intermediate position 44 between the contact positions 43. Here, the contact position 42 is the contact position between the roll 2a above the injection nozzle 3 and the slab surface 41, and the contact position 43 is the contact position between the roll 2b below the injection nozzle 3 and the slab surface 41. The contact position between and. Further, the cooling water injection axis J1 of the injection nozzle 3 is provided so as to be inclined diagonally upward with respect to the perpendicular line of the slab surface 41. As shown in FIG. 2, the injection nozzle 3 may be provided so that the long-axis direction ends of the spray ranges 46 adjacent to each other in the front-rear direction (Y direction) overlap each other vertically, or do not overlap. It may be provided as follows.
　Such a configuration can be realized as follows.
[0022]
　First, as the injection nozzle 3 used in the secondary cooling device of the present embodiment, for example, as shown in FIG. 3, a two-fluid nozzle having the following configuration can be preferably used.
That is, as the injection nozzle 3, as shown in FIG. 3, a nozzle body 11 having a prismatic nozzle head and a plurality of (a pair in the drawing) groove portions 12 and 12'formed at the tip of the nozzle body 11 , A configuration including a pair of discharge ports 13 and 13'opening in a long and narrow shape in the groove portions 12 and 12' and a plurality of flow paths 14, 15 and 16 connected to the discharge ports 13 and 13' can be adopted. .. The other end is formed deeper than one end of the grooves 12 and 12', and the position of the center of the discharge ports 13 and 13'in the grooves 12 and 12'is the axis of the nozzle body 11. It is located on the other end side of the grooves 12 and 12', deviating from the groove.
　In the injection nozzle 3, the fluid injected from the discharge ports 13 and 13'flows along the discharge wall forming the groove portions 12 and 12'. Moreover, since the center of the discharge ports 13 and 13'is located on the other end (deep groove portion) side of the groove portions 12 and 12', the fluid from the discharge ports 13 and 13'is more on the deep groove portion side. A lot flows in. Therefore, it is possible to increase the injection amount from the other end portion (thick portion or deep groove portion of the discharge wall) while regulating the injection amount from one end portion (thin wall portion or shallow groove portion of the discharge wall). As a result, the cooling water (gas-liquid mixture mist) is mainly injected into the diagonally forward region of the nozzle tip. Therefore, according to the injection nozzle 3, the shape of the spraying range 46 on the slab surface 41 can be an eccentric elliptical shape as shown in the lower figure of FIG. More specifically, the center 460-1 of the spraying range 46-1 moves to the reference numeral 460-3 by injecting the cooling water intensively into the diagonally forward region 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 jetted from the tip of the nozzle has an eccentric elliptical shape.
[0023]
　The groove portions 12 and 12'may be inclined by 3 ° to 40 ° with respect to a direction orthogonal to the axis of the nozzle body 11.
That is, in at least one groove portion 12, 12', the line connecting the lower end of the bottom portion of one end portion (shallow groove portion) and the lower end portion of the bottom portion of the other end portion (deep groove portion) is with respect to the axis of the nozzle body 11. It may be inclined by about 3 ° to 40 ° with respect to the orthogonal direction. The flow rate distribution (injection amount distribution from each end side) to each end of the groove portions 12 and 12'can be adjusted by this inclination angle.
[0024]
　As described above, in the injection nozzle 3, one end of the grooves 12 and 12'(injection port) for injecting the cooling water W is formed deeper than the other end, so that FIGS. 4A and 4B As shown in the above, the cooling water injection axis J1 shown by the solid line is inclined with respect to the axis 310 of the nozzle head 31 at an inclination angle α1. Specifically, the cooling water injection axis J1 of the injection nozzle 3 is inclined at an inclination angle α1 with respect to the long axis direction of the cooling water W spraying range 46 on the slab surface 41. The axis 310 is a perpendicular line from the nozzle head 31 to the slab surface 41. When the cooling water injection axis J1 is not tilted with respect to the major axis direction of the spray range 46 and the major axis direction of the spray range 46 is rotated about the axis 310 with respect to the horizontal direction, the two-point chain line is shown in the lower figure of FIG. As shown by, the intersection position of the axis 310 of the nozzle head 31 and the slab surface 41 coincides with the center 460-1 of the spraying range 46-1, and the cooling water has a symmetrical pattern centered on the axis 310. W is injected. On the other hand, when the cooling water injection axis J1 is tilted with respect to the major axis direction of the spray range 46, the intersection position of the axis 310 and the slab surface 41 is the spray range 46-as shown by the solid line in FIG. 4B. Since it does not coincide with the center 460-2 of 2, the cooling water W is injected in an asymmetric pattern centered on the axis 310. In this embodiment, the cooling water W is sprayed onto the slab surface 41 in an asymmetric pattern in this way.
[0025]
　As shown in FIG. 4B, the inclination angle α1 of the cooling water injection axis J1 with respect to the major axis direction of the spraying range 46 is preferably inclined by 30 ° to 40 °. The spread angle of the cooling water W injected from the injection nozzle 3 in the long axis direction is such that the narrow angle side angle α2 exceeds −90 ° and is less than 90 °, and the wide angle side angle α3 is the inclination angle α1 or more and 95 ° or less. preferable. The narrow angle side angle α2 is the angle of the cooling water W spreading to the narrow angle side (in FIG. 4B, the left side of the paper surface with respect to the axis 310) with respect to the axis 310, and the wide angle side angle α3 is a wide angle with reference to the axis 310. It is an angle of the cooling water W spreading to the side (in FIG. 4B, the right side of the paper surface with respect to the axis 310).
[0026]
　Then, the nozzle head 31 of the injection nozzle 3 is sprayed with the cooling water W on the slab surface 41 from a state in which the axis 310 thereof is parallel to the perpendicular line of the slab surface 41 and is positioned between the upper and lower rolls 2a and 2b. By rotating the long axis of the range 46-2 upward around the axis 310 at a rotation angle β, as shown by the solid lines in FIGS. 5A and 5B, the long axis LA of the spray range 46-2 is designated by the symbol LA-. It faces diagonally upward as shown by 1. As a result, the cooling water injection axis J1 is inclined diagonally upward with respect to the perpendicular line of the slab surface 41, and the spraying range moves from the position of reference numeral 46-2 to the position of reference numeral 46-3. With such a configuration, as shown in FIG. 2, the wide-angle side of the spraying range 46 in the long axis direction can be inclined diagonally upward 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 injection axis J1 of the injection nozzle 3 is inclined diagonally upward with respect to the perpendicular line of the slab surface 41. be able to.
[0027]
　As a result, as shown in FIG. 6A, the cooling water W is sprayed into the spraying range 46 centered in the vertical direction at a position above the intermediate position 44 in the line of sight of FIG. That is, as shown by the solid line in FIG. 6 (B), the cooling water W is the spray range 46 shifted upward from the conventional spray range 45 in FIG. 9 (A) (indicated by the broken line in FIG. 6 (B)). Is sprayed on. Further, the thickness (height) of the spraying range 46 in the vertical direction (Z direction) when viewed from the line of sight (+ Y direction side) of FIG. 6 is the vertical direction (height) of the conventional spraying range 45 of FIG. 9 (A). It becomes thicker than (Z direction). Further, by inclining the cooling water injection axis J1 diagonally upward, as shown by the two-point chain line in the lower figure of FIG. 2, the cooling water injection axis J1 is not inclined with respect to the long axis direction of the spraying range 46. The amount of injection in the diagonally upward direction can be increased as compared with the configuration in which the cooling water W is injected in a symmetrical pattern centered on the axis 310. Further, the upper end position 461 of the spraying range 46 on the slab surface 41 can be positioned above the upper end position of the spraying range 45 on the conventional slab surface 41.
[0028]
　The rotation angle β that rotates upward around the axis 310 of the injection nozzle 3 (spraying range 46) is preferably inclined by 5 ° to 15 °.
　The distance M (see the lower figure of FIG. 2) from the intermediate position 44 of the pair of rolls 2 to the center 460-3 of the spraying range 46 in the vertical direction (Z direction) is more than 0 mm (L1 / 2) mm or less. preferable.
　The distance L2 (X direction) from the tip of the nozzle head 31 of the injection nozzle 3 to the slab surface 41 (see the lower figure of FIG. 1) is preferably 50 mm or more and 450 mm or less.
　The spray range 46 may or may not include the intermediate position 44 of the slab surface 41. The distance L3 (see the lower figure of FIG. 1) from the upper end position 461 of the spraying range 46 to the contact position 42 with the upper roll 2a on the slab surface 41 is preferably 0 mm or more and 200 mm or less. The cooling water W may be sprayed so as to come into contact with the upper roll 2a, but it is preferable that the cooling water W does not come into contact with the roll 2a. 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 slab surface 41 is 80 mm, the distance L3 is preferably about 45 mm.
　The intersection position of the axis 310 of the injection nozzle 3 and the slab surface 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 spraying range 46 may be alternately different for each row in the width direction of the slab 4, may be the same, or in one row. The slab 4 may be symmetrical with the center in the width direction as a boundary.
[0029]
[Action of Secondary Cooling Device for
　Continuous Casting ] Next, the action of the secondary cooling device 1 for continuous casting will be described. In the secondary cooling method for continuous casting according to the same embodiment, the slab is cooled by the cooling mechanism as shown in FIG. FIG. 6 shows a schematic view (A) showing a part of the secondary cooling device for continuous casting, a graph (B) showing the relationship between the casting distance and the water content density, and the relationship between the casting distance and the slab surface temperature. The graph (C) is shown. In the following, a case where the upper roll 2a in FIG. 6A is the first roll 2 of the secondary cooling device 1 will be described.
[0030]
　When cooling the slab 4, when a predetermined position on the slab surface 41 approaches the contact position 42 with the roll 2a that first contacts, as shown by the solid line in FIG. 6C, the slab surface 41 The temperature of the above begins to decrease due to roll cooling due to contact with the roll 2a, and continues to decrease until the distance from the contact position 42 downward is a predetermined distance or more.
　At this time, the effect margin (difference in temperature immediately after the roll cooling of the present embodiment and the conventional configuration) ΔTr1 after the roll cooling by the roll 2a that comes into contact first becomes 0 ° C.
[0031]
　After that, the temperature of the slab surface 41 rises due to the first reheat until the predetermined position on the slab surface 41 falls within the spray range 46, and when it enters the spray range 46, it is sprayed until it passes there. It keeps falling due to cooling.
　At this time, the spraying range 46 shown by the solid line in FIG. 6B shifts upward from the conventional spraying range 45 shown by the broken line in FIG. 6 when viewed from the line of sight of FIG. 6, and in the vertical direction (Z direction). It's getting thicker. Therefore, the first heat recovery period shown by the solid line in FIG. 6C is shorter than that in the conventional configuration shown by the broken line in FIG. 6, and spray cooling starts earlier than in the conventional configuration. That is, the slab surface 41 can be cooled before the temperature rises significantly due to the reheat. Therefore, the amount of reheat is reduced as compared with the conventional configuration, the temperature of the slab 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 cooling efficiency E9 of the conventional configuration, and the slab surface 41 is cooled to a lower temperature by spray cooling. Further, since the cooling water injection axis J1 is inclined diagonally upward and the injection amount in the diagonally upward direction is increased, the amount of heat recovery in the first heat recovery period can be further reduced, and the heat transfer coefficient during spray cooling can be increased. It can be made even larger.
[0032]
　When the predetermined position on the slab surface 41 passes through the spraying range 46, the temperature of the slab surface 41 rises due to the second reheating, but the temperature at the start of the second reheating is lower than that of the conventional configuration. Therefore, the temperature at the start of cooling by the roll 2b that comes into second contact also becomes low, and the effect margin ΔTr2 after the roll cooling by the roll 2b becomes larger than 0 ° C. After that, the temperature of the slab 4 is gradually lowered and cooled by repeating the cycle of the first reheating, the spray cooling, the second reheating, and the roll cooling described above.
　In this cooling process, the effect margin after roll cooling gradually increases toward the downstream in the casting direction, so that the cooling time of the slab is shortened as compared with the conventional configuration.
[0033]
[Effects of the
　present embodiment ] According to the present embodiment, there are the following effects.
　Since the center of the spraying range 46 is above the intermediate position 44 and the cooling water injection axis J1 is inclined diagonally upward with respect to the perpendicular line of the slab surface 41, it is above the injection nozzle 3. The spraying destination of the cooling water W can be brought close to the contact position 42 between the roll 2a and the slab surface 41. As a result, the slab surface 41 that goes downward through the contact position 42 can be cooled before the temperature rises significantly due to the reheat. Therefore, the cooling effect of the slab 4 can be enhanced as compared with the conventional case, and the productivity can be improved. Moreover, since the cooling effect of the slab 4 can be enhanced without providing new equipment, the cost does not increase.
　Therefore, according to the continuous casting secondary cooling device and the secondary cooling method of the present embodiment, it is possible to improve the productivity without causing an increase in cost.
[0034]
[Variations] The
　present invention is not limited to the above embodiment, and various improvements and design changes can be made without departing from the gist of the present invention. In addition, the present invention can be implemented. The specific procedure and structure at the time of the above may be other structures as long as the object of the present invention can be achieved.
[0035]
　For example, the injection nozzle 3 in which the cooling water injection axis J1 is not inclined with respect to the major axis direction of the spray range 46 may be used. In this case, by arranging the tip of the injection nozzle 3 so as to be closer to the slab surface 41 than the position shown in FIG. The intersection position of the axis 310 of the nozzle head 31 and the slab surface 41 coincides with the center 460 of the spraying range 46. Further, the long axis of the spraying range 46 rotates around the axis 310, which is a perpendicular line from the injection nozzle 3 to the slab surface 41, and the center 460 of the spraying range 46 is located above the intermediate position 44. May be good.
　Even with such a configuration, the spraying range 46 of the cooling water W can be shifted upward and thickened in the vertical direction (Z direction) as compared with the conventional configuration, and the productivity can be increased without increasing the cost. It can be improved.
　A one-fluid nozzle may be used as the injection nozzle 3.
Example
[0036]
　Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples.
[0037]
　A simulation for verifying the effect of the present invention will be described.
　The following settings were made as parameters common to the examples and the comparative examples.
　　　Roll diameter R: 150 mm or more and 360 mm or less
　　　Roll pitch L1: 190 mm or more and 430 mm or less
　　　Distance from the tip of the injection nozzle to the slab surface L2: 80 mm or more and 430 mm or less From
　　　the upper end position of the spraying range to the upper roll on the slab surface Distance to contact position L3: Exceeds 0 mm (L1 / 2) mm or less
　　　Jet water volume: 8 L / min or more
　　　per nozzle 80 L / min or less Number of nozzles in the width direction per roll: 1 to 16
　　　Casting speed: 2 .0 m / min
　　　Carbon content in molten steel: 0.04%
　　　slab width: 1500 mm
　　　slab thickness: 250 mm
[0038]
　Further, the arrangement state of the roll 2 and the injection nozzle 3 in the embodiment was set as shown in FIG. 2, and the arrangement state of the roll 2 and the injection nozzle 9 in the comparative example was set as shown in FIG. In the examples and comparative examples, "the inclination angle α1 of the cooling water injection axis J1 with respect to the long axis direction of the spraying range 46", "the narrow angle side angle α2 of the cooling water W with respect to the axis 310", and "the axis 310 as a reference". Wide angle side angle α3 of the cooling water W, “Rotation angle β of injection nozzles 3 and 9 (spraying range 46) rotating upward around the axis 310”, “From the intermediate position 44 of the pair of rolls 2 in the vertical direction The "distance M to the center 460 of the spray range 46" is shown in Table 1 below.
　In the comparative example, the cooling water injection axis J1 is not inclined with respect to the major axis direction of the spray range 46, and the intersection position between the axis 910 of the nozzle head 91 and the slab surface 41 is the center 460 of the spray range 46. An injection nozzle 9 that matches the above was used. Since the spread angle of the cooling water W injected from the injection nozzle 9 in the long axis direction is the same on both sides (left and right sides) in the long axis direction with respect to the axis 910, in Table 1, the angles obtained by combining the left and right sides. Is shown.
[0039]
[table 1]

[0040]
　Then, a simulation of secondary cooling of continuous casting was performed. FIG. 8 is an example of the results showing the slab surface temperature change in the numerical range shown in Table 1.
　As shown in FIG. 8, the effect margin after roll cooling due to contact with the first roll (difference in temperature immediately after roll cooling in Examples and Comparative Examples) ΔTr1 was 0 ° C., but the first after roll cooling. recuperation period the embodiment shown by the solid line is shorter than the comparative example shown by the broken line, condensate heat embodiments could be 7 ° C. reduced from condensate heat of the comparative example (in FIG. 8, shown as "ΔTa")
　also 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 margin immediately after spray cooling (difference in temperature immediately after spray cooling of the example and the comparative example) ΔTb1 Was 33 ° C.
　Further, the effect margins after roll cooling due to contact with the second and third rolls are 14 ° C. and 25 ° C., and then the effect margin after roll cooling gradually increases toward the downstream in the casting direction. It was. Further, the effect margins ΔTb2 and ΔTb3 immediately after the second and third spray cooling were 49 ° C. and 59 ° C., and then the effect margin immediately after the spray cooling gradually increased toward the downstream in the casting direction.
　As a result, it was confirmed that the cooling time of the slab was shortened by 0.3 min in the examples as compared with the comparative examples.
Industrial applicability
[0041]
　According to the present invention, it is possible to provide a continuous casting secondary cooling device and a secondary cooling method that can improve productivity without causing an increase in cost. Therefore, the industrial applicability is great.
Description of the sign
[0042]
1 ... Secondary cooling device
2, 2a, 2b ... Roll
3 ... Injection nozzle
4 ... Cast piece
41 ... Piece surface
42, 43 ... Contact position
44 ... Intermediate position
46 ... Spray range
460 ... Center
J1 ... Cooling water injection axis
W …Cooling water
The scope of the claims
[Claim 1]
　A secondary cooling device for continuous casting that injects cooling water onto the surface of a slab sent in the casting direction to cool it, and has
　a plurality of rolls arranged side by side in the vertical direction along the casting direction.
　An injection nozzle for injecting the cooling water onto the surface of the slab from between the plurality of rolls
is provided, and the
　injection nozzle is such that
　　the cooling water injection axis of the injection nozzle sprays the cooling water on the surface of the slab. It is inclined with respect to the long axis direction of the range, the long axis of the
　　spraying range rotates upward around the axis which is a perpendicular line from the injection nozzle to the surface of the slab, and
　　the center of the spraying range is the injection nozzle.
It is provided so as to be located above the intermediate position between the contact position between the roll and the slab surface above the roll and the contact position between the roll and the slab surface below . A continuous casting secondary cooling device.
[Claim 2]
　In the injection nozzle, the
　　cooling water injection axis is inclined by 30 ° to 40 ° with respect to the long axis direction of the cooling water spraying range on the slab surface, and the long axis of the spraying range is
　　from the injection nozzle. The
secondary cooling device for continuous casting according to claim 1, wherein the secondary cooling device for continuous casting is provided so as to rotate upward by 5 ° to 15 ° around an axis which is a perpendicular line to the surface of the slab .
[Claim 3]
　A secondary cooling method for continuous casting, which comprises a step of injecting cooling water onto the surface of a slab from injection nozzles arranged between a plurality of rolls arranged in a vertical direction along the casting direction to cool the slab.
The cooling water injection axis of the injection nozzle is inclined with respect to the long axis direction of the cooling water spraying range on the
　slab surface, and the long axis of the spraying range is a perpendicular line from the injection nozzle to the slab surface. Rotates upward around the axis, and
　the center of the spraying range is the contact position between the roll and the slab surface above the injection nozzle and the contact between the roll and the slab surface below. A
secondary cooling method for continuous casting, characterized in that it is located above the intermediate position with the position .