JP4910974B2 - Steel sheet bottom surface cooling device - Google Patents

Description

  The present invention relates to a steel sheet lower surface cooling apparatus that cools the lower surface of a steel sheet after finish rolling in a manufacturing process of a high strength steel sheet or the like.

  In the cooling process included in the manufacturing process of high-strength steel, the cooling start temperature is high and the cooling stop temperature is low, so that the cooling temperature range is large and temperature unevenness is likely to occur. This uneven temperature contributes to the shape failure (flatness failure) of the steel sheet that occurs after cooling. If a poorly shaped steel plate is transported to a downstream process, it may cause a failure or the like. Therefore, it is necessary to correct the shape of the poorly shaped steel plate. However, if the strength of the product is high, it becomes difficult to completely correct flatness defects (warping, ear waves, middle stretched shape, etc.) generated after cooling with an online leveler. Therefore, it is important to flatten the shape before cooling, prevent temperature unevenness in the thickness direction of the steel material during cooling, and suppress shape defects after cooling. Furthermore, in order to prevent product material strength variation (mainly product surface strength and back surface strength variation), it is important to control the temperature change history of the steel sheet front and back (upper and lower surfaces) during cooling to be the same. .

  In general, the cooling medium released to the steel sheet surface (hereinafter sometimes referred to as “cooling water”) stays on the steel sheet surface (hereinafter sometimes referred to as “upper surface”), The cooling water discharged to the upper surface of the steel plate is stirred, but the cooling water released to the rear surface of the steel plate (hereinafter sometimes referred to as “lower surface”) falls down below the lower surface of the steel plate. Therefore, if the amount of cooling water discharged to the upper surface of the steel sheet (hereinafter referred to as “cooling water amount”) and the amount of cooling water discharged to the lower surface of the steel sheet are the same, the cooling capacity is larger on the upper surface side, and the steel sheet is sprayed using a spray nozzle or the like. In order to equalize the cooling capacity of the upper surface and the cooling capacity of the lower surface of the steel sheet, the amount of cooling water discharged from the nozzle disposed on the lower surface side of the steel sheet is set to the amount of cooling water discharged from the nozzle disposed on the upper surface side of the steel sheet. It needs to be doubled. For this reason, the maximum cooling capacity of the entire cooling zone is easily influenced by the cooling capacity of the lower surface of the steel sheet, the control range of the cooling capacity is narrowed, and the variation in the stop temperature increases depending on the size of the steel sheet (plate thickness, width, etc.). .

  Furthermore, the cooling water discharged | emitted to the steel plate lower surface falls to the downward direction of a steel plate from the conveyance direction upstream or downstream side of a steel plate, or the width direction both ends of a steel plate. Cooling water that falls from both ends in the width direction of the steel plate to the bottom of the steel plate moves from the center in the width direction of the steel plate to the end in the width direction of the steel plate and drops from the end in the width direction to the bottom of the steel plate. On the lower surface of the steel plate, the temperature tends to excessively decrease at both ends in the width direction in contact with a larger amount of water than in the center portion in the width direction. Thus, when the width direction edge part of a steel plate is cooled too much, temperature nonuniformity will arise in the width direction of a steel plate, and it will become a cause of a shape defect. Therefore, in order to suppress the shape defect after cooling, it is important to reduce temperature unevenness in the width direction of the lower surface of the steel plate.

  As a technique aiming at improving the cooling ability of the lower surface of the steel plate, for example, in Patent Document 1, a water tank having a nozzle is arranged below the water surface, and the cooling water discharged from the nozzle is used as the nozzle and the steel plate. By colliding with the lower surface of the steel plate through a conduit arranged between the two, the water in the water tank collides with the lower surface of the steel plate as an accompanying water flow, so that a large amount of cooling water collides with the lower surface of the steel plate, thereby cooling the lower surface of the steel plate. A lower surface cooling device for a high temperature steel sheet is disclosed. In Patent Document 2, a plurality of columnar coolant injection nozzles (hereinafter referred to as “columnar injection nozzles”) are provided in the width direction and the longitudinal direction of a nozzle header having an upper surface parallel to the lower surface of the steel plate, and each nozzle along the longitudinal direction. A cooling device for a lower surface of a steel sheet is disclosed in which the rows are inclined rows having different angles toward the lower surface of the steel sheet.

JP 2001-1027 A Japanese Patent Laid-Open No. 62-259610

  However, the technique disclosed in Patent Document 1 has a problem that when the temperature of the cooling water in the water tank rises, particularly in summer, the cooling capacity of the lower surface of the steel sheet decreases and it becomes difficult to control the cooling capacity. . Furthermore, in the technique disclosed in Patent Document 1, a configuration is disclosed in which only the cooling water is stored in a water tank disposed below the steel plate, and the moving direction of the cooling water after colliding with the lower surface of the steel plate is controlled. Absent. For this reason, the technique disclosed in Patent Document 1 has a problem that the temperature unevenness in the width direction of the lower surface of the steel sheet cannot be reduced. Further, even the technique disclosed in Patent Document 2 has a problem that the effect of reducing temperature unevenness in the width direction of the lower surface of the steel sheet is small.

  Then, this invention makes it a subject to provide the lower surface cooling device of a steel plate which can reduce the temperature nonuniformity in the width direction of a steel plate lower surface.

  The present invention will be described below. In addition, in order to make an understanding of this invention easy, the reference sign of an accompanying drawing may be appended in parentheses, but this invention is not limited to the form of illustration by it.

The present invention includes a header portion (3) disposed between a plurality of transport rolls (2, 2,...) Disposed at intervals in the traveling direction of the steel plate (1), and the header portion (3). A plurality of jet nozzles (4, 4,...), And the lower surface of the steel sheet transported on the transport roll is cooled by the cooling medium discharged from the spray nozzle, and discharged onto the upper surface of the header portion. A rectifying means (5, 5,...) That prevents the cooling medium from moving in the width direction of the steel sheet and prevents the discharged cooling medium from moving in the traveling direction of the steel sheet is provided, The rectifying means is provided between the horizontal plane passing through the axes of the plurality of transport rolls and the lower surface of the steel plate, and further, the discharged cooling medium moves in the traveling direction of the steel plate (1) on the upper surface of the header portion. Movement control means (6, 6) are provided to prevent the movement The height of the control means, and wherein the lower than the height of the rectifying means (5,5, ...), a bottom cooling device of the steel plate (10).

  Here, the form of the “injection nozzle (4, 4,...)” Is not particularly limited as long as it is an injection nozzle used in a cooling device for cooling the rolled steel plate (1). Specific examples of the injection nozzles (4, 4,...) That are preferably used in the present invention include columnar injection nozzles. Furthermore, the “cooling medium” means a fluid used when cooling the steel plate (1), and specific examples of the cooling medium that can be used in the present invention include industrial water. Further, the “rectifying means (5)” means that the cooling medium discharged from the injection nozzle (4, 4,...) And colliding with the lower surface of the steel sheet is prevented from moving in the width direction of the steel sheet, and the traveling direction of the steel sheet The means is not particularly limited as long as it is a means that does not hinder the movement to the right, and for example, it can be constituted by a plurality of metal plates (5, 5,...).

  In the present invention provided with the movement control means (6, 6), the rectification means (5, 5,...) And the movement control means are preferably joined.

  According to the steel plate lower surface cooling device (10) of the present invention, the rectifying means (5, 5,...) Is provided on the upper surface of the header portion (3). Therefore, by preventing the cooling water after colliding with the lower surface of the steel plate (1) from moving in the width direction of the steel plate (1), it becomes possible to reduce temperature unevenness in the width direction of the lower surface of the steel plate. . Therefore, according to this invention, the lower surface cooling device (10) of the steel plate which can reduce the temperature nonuniformity in the width direction of a steel plate lower surface can be provided, and generation | occurrence | production of a shape defect can be suppressed. Therefore, according to the present invention, it is possible to omit the process of cutting a poorly shaped steel plate in the middle of the line or correcting the shape with a cold leveler or a press, so that the production cost can be reduced and the product Quality can also be improved. Furthermore, according to the steel sheet lower surface cooling device (20) of the present invention, since the movement control means (6, 6) is provided, it becomes possible to improve the rigidity of the rectifying means (5, 5,...) By adopting a form in which the rectifying means (5, 5,...) And the movement control means (6, 6) are joined, the rectifying means (5, 5,...) And the movement control means (6, 6) can be easily formed. It becomes possible to remove or improve and change in some cases.

  Inventors examined the new water cooling method in order to control the cooling capacity of the steel plate lower surface. In the steel plate lower surface cooling device according to the current technology, most of the cooling water that has collided with the steel plate lower surface falls from both ends in the width direction of the steel plate to the lower side of the cooling device. Therefore, as a new cooling method, a water film is formed on the upper surface of the header for lower surface cooling by virtue of arranging a member for controlling the moving direction of the cooling water on the upper surface of the header provided in the cooling device, and cooling with strong stirring. Therefore, the lower surface cooling ability of the steel sheet was improved.

  (A) If the upper surface of the header and the lower surface of the steel plate are brought close to each other, and if cooling water of an amount more than the cooling water falling below the cooling device is supplied from the nozzle disposed in the header to the lower surface of the steel plate, Cooling water can be present between the steel plate lower surface and the steel plate lower surface at all times (a water film can be formed on the lower surface of the steel plate). And if a cooling water is discharge | released toward the lower surface of the steel plate in which the water film was formed, since the cooling water which comprises a water film can be stirred strongly, the lower surface cooling capability of a steel plate can be improved.

  (B) Further, a water flow control plate (hereinafter sometimes referred to as “rectifying means”) is installed on the upper surface of the header to control the water flow. That is, a plate parallel to the steel plate traveling direction is provided on the header upper surface, and the cooling water existing on the header upper surface is restricted from moving in the width direction of the steel plate to prevent overcooling at both ends in the width direction of the steel plate. Can do.

  (C) If a rectification | straightening means is provided in the header upper surface, since the fall of the cooling water from the board width direction of a steel plate can be suppressed, the lower surface cooling capability of a steel plate can be improved.

  As a result of studying the embodiment based on the above-mentioned ideas (A) to (C), the inventors, from the columnar injection nozzle, in the lower surface portion of the steel sheet facing the upper surface of the header disposed between the transport rolls. It has been found that the cooling ability can be improved by causing the discharged columnar cooling water jet to collide with the lower surface of the steel plate vertically. At this time, by increasing the vertical momentum of the columnar cooling water jet toward the lower surface of the steel plate, the vapor film generated on the lower surface of the steel plate can be forcibly eliminated, and the lower surface of the steel plate can be strongly cooled under nucleate boiling conditions. become. Furthermore, by restricting the movement of the cooling water that has collided with the lower surface of the steel sheet in the width direction of the steel sheet, it is possible to suppress the flow of cooling water from the center of the steel sheet in the width direction toward the end in the width direction of the steel sheet. It has been found that it is possible to prevent overcooling at the end in the width direction.

The present invention has been made based on the above findings.
Embodiments of the present invention will be described below.

1. First Embodiment FIG. 1 is a conceptual diagram showing a form example of a steel sheet lower surface cooling device according to the first embodiment (hereinafter sometimes referred to as “cooling device according to the first embodiment”). FIG. 2 is a conceptual diagram illustrating a positional relationship between the cooling device according to the first embodiment, a steel plate, and a transport roll. 2 is the sheet thickness direction of the steel sheet, the left-right direction of the sheet of FIG. 2 is the conveying direction of the steel sheet, and the back / front direction of FIG. 2 is the width direction of the steel sheet. Hereinafter, the cooling device according to the first embodiment will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the cooling device 10 according to the first embodiment (hereinafter sometimes referred to as “cooling device 10”) includes a header portion 3 and a plurality of columnar injection nozzles arranged in the header portion 3. (Hereinafter referred to as “injection nozzles 4, 4,...”), And rectifying means 5, 5,... (Hereinafter referred to as “metal plates 5, 5,. Is sometimes provided.). When using the cooling device 10, as shown in FIG. 2, the header part 3 is arrange | positioned between the conveyance rolls 2, 2, ... which convey the steel plate 1. As shown in FIG. And a cooling medium (cooling water) is supplied to the header part 3 via piping which is not shown in figure, and it cools toward the lower surface of the steel plate 1 from the some injection nozzle 4, 4, ... arrange | positioned at the said header part 3. By releasing water, the lower surface of the steel plate 1 is cooled. As shown in FIGS. 1 and 2, the cooling device 10 is provided with metal plates 5, 5,... Arranged so that the longitudinal direction is substantially parallel to the traveling direction of the steel plate 1. And the said metal plates 5, 5, ... are arrange | positioned in the space between the horizontal surface which passes along the axial center of the conveyance rolls 2, 2, ..., and a steel plate lower surface.

  Since the cooling device 10 is provided with the metal plates 5, 5,..., The cooling water discharged from the injection nozzles 4, 4,. 1 is prevented from moving in the width direction. When the movement is hindered, the flow of cooling water from the center in the width direction of the steel plate 1 toward the end in the width direction is suppressed. The amount of cooling water that comes into contact with both ends can be reduced. Thus, if the amount of cooling water in contact with both ends in the width direction is reduced, it is possible to reduce overcooling at both ends in the width direction of the lower surface of the steel plate 1. The temperature unevenness in the width direction on the lower surface can be reduced.

  Furthermore, according to the cooling device 10 including the metal plates 5, 5,..., The metal plate 5, 5,. As shown in FIG. 2, when it is arranged in the vicinity of the lower surface of the steel plate 1 (the position where the distance between the tip of the injection nozzles 4, 4,... And the lower surface of the steel plate 1 is about 30 mm to 100 mm; the same applies hereinafter) The cooled water comes into contact with the lower surface of the steel plate 1, and a water film is formed on the lower surface of the steel plate 1. As described above, when the lower surface of the steel plate 1 is cooled using the cooling device 10, a water film that is formed on the upper surface of the steel plate 1 can be formed on the lower surface of the steel plate 1. If it is, the lower surface cooling ability of the steel plate 1 can be improved.

2. 2nd Embodiment FIG. 3: is a conceptual diagram which shows the form example of the lower surface cooling device (henceforth "the cooling device concerning 2nd Embodiment") of the steel plate of this invention concerning 2nd Embodiment. FIG. 4 is a conceptual diagram illustrating a positional relationship between the cooling device according to the second embodiment, a steel plate, and a transport roll. 4 is the thickness direction of the steel sheet, the left-right direction in FIG. 4 is the conveyance direction of the steel sheet, and the back / front direction of FIG. 4 is the width direction of the steel sheet. 3 and 4, the same reference numerals as those used in these drawings are attached to components having the same configurations as those in FIGS. Hereinafter, the cooling device according to the second embodiment will be described with reference to FIGS. 3 and 4.

  As shown in FIG. 3, the cooling device 20 according to the second embodiment (hereinafter sometimes referred to as “cooling device 20”) includes a header portion 3 and a plurality of injection nozzles 4 disposed in the header portion 3. .., And metal plates 5, 5,... As rectifying means and movement control means 6, 6 (hereinafter referred to as “metal plates 6, 6”). ) Is provided. In the cooling device 20, the metal plates 5, 5,... Are disposed so that the longitudinal direction thereof is substantially parallel to the traveling direction of the steel plate 1, and the metal plates are lower in height than the metal plates 5, 5,. 6 and 6 are arranged so that the longitudinal direction is substantially parallel to the width direction of the steel plate 1, and the metal plates 5, 5, ... and the metal plates 6 and 6 are integrated by being joined together. . .. And the metal plates 6, 6 are arranged in a space between a horizontal plane passing through the axes of the transport rolls 2, 2,.

  When using the cooling device 20, as shown in FIG. 4, the header part 3 is arrange | positioned between the conveyance rolls 2, 2, ... which convey the steel plate 1. As shown in FIG. When the cooling device 20 is used, cooling water is supplied to the header portion 3 through a pipe (not shown), and the plurality of spray nozzles 4, 4,. The lower surface of the steel plate 1 is cooled by discharging the cooling water.

  Like the cooling device 10, the cooling device 20 is also provided with the metal plates 5, 5..., So that the movement of the cooling water in the width direction of the steel plate 1 can be prevented by the metal plates 5, 5. Therefore, the cooling device 20 can also reduce the temperature unevenness in the width direction of the lower surface of the steel plate 1. In addition to the configuration of the cooling device 10, the cooling device 20 is provided with metal plates 6, 6 that are lower than the metal plates 5, 5,. By disposing the metal plates 6 and 6 in the form in which the longitudinal direction is substantially parallel to the width direction of the steel plate 1 on the upstream side and the downstream side in the conveying direction of the steel plate 1 on the upper surface of the header portion 3, 5 can be improved in rigidity, and by arranging the metal plates 5, 5,... It becomes easy to remove these from the header part 3. Moreover, if the cooling device 20 of this form is arrange | positioned in the lower surface vicinity of the steel plate 1 as shown in FIG. 4, the remaining cooling water can be made to contact with the lower surface of the steel plate 1 (a water film is formed on the lower surface of the steel plate 1). Further, the cooling water accumulated on the upper surface of the header portion 3 can be strongly agitated by the cooling water discharged from the injection nozzles 4, 4,... 1 lower surface cooling ability can be improved.

  In the cooling devices 10 and 20 of the present invention, the height of the metal plates 5, 5,... Is a height that does not contact the lower surface of the steel plate 1 and can restrict the movement of the cooling water in the width direction of the steel plate. Although it will not specifically limit if it is height, It is preferable that it is 5-20 mm lower than the upper end surface (lower surface of the steel plate 1) of the conveyance rolls 2 and 2. FIG. If it is less than 5 mm, the steel plate 1 may come into contact with the metal plates 5, 5,..., And if it exceeds 20 mm, it becomes difficult to sufficiently limit the movement of the cooling water in the width direction of the steel plate.

  Moreover, in the cooling devices 10 and 20 of the present invention, the number of the metal plates 5, 5,... Provided in the header portion 3 is particularly limited as long as it is a number that can restrict the movement of the cooling water in the width direction of the steel plate. Is not to be done. Furthermore, although the space | interval in the width direction of the steel plate 1 of the metal plates 5, 5, ... is not specifically limited, It is preferable to arrange | position at 50 mm-200 mm space | interval. Here, the speed at which the cooling water in contact with the center in the width direction of the lower surface of the steel plate 1 moves in the width direction of the steel plate 1 is that the cooling water in contact with the end in the width direction of the lower surface of the steel plate 1 is in the width direction of the steel plate 1. The distance between the metal plates 5, 5,... Arranged at the center in the width direction of the steel plate 1 is the metal plates 5, 5,. It can be made wider than the interval.

  In the cooling devices 10 and 20 of the present invention, the metal plates 5, 5,... Are from the injection nozzles 4, 4,. It is preferable to arrange at a position that does not obstruct the flow of the cooling water discharged toward. Furthermore, in the cooling devices 10 and 20 of the present invention, the discharge direction of the cooling water discharged from the injection nozzles 4, 4,... Toward the lower surface of the steel plate 1 is not particularly limited. From the viewpoint of allowing the cooling water released from 4,... To directly contact the lower surface of the steel plate 1 without contacting the metal plates 5, 5,. It is preferable that the cooling water is discharged to the upper side in the normal direction on the upper surface of the header portion 3.

  Moreover, in the cooling devices 10 and 20 of the present invention, the distance between the lower surface of the steel plate 1 and the upper surface of the header portion 3 is not particularly limited. From the viewpoint of making it easy to improve the cooling ability of the lower surface of the steel sheet 1 by bringing it into contact with the lower surface, the distance is preferably 100 mm or less. On the other hand, from the viewpoint of securing a space for arranging the metal plates 5, 5,..., The distance is preferably 30 mm or more.

  In the cooling device 20 of the present invention, the height of the metal plates 6, 6 is not particularly limited as long as it is lower than the height of the metal plates 5, 5,. From the viewpoint of improving the effect of hindering the flow of the cooling water to suppress the supercooling at the end in the width direction of the steel plate 1, the height of the metal plates 6, 6 is set to the metal plates 5, 5, It is preferable to make it lower by 10 mm or more than the height of. On the other hand, the upper limit of the difference between the height of the metal plates 6, 6 and the height of the metal plates 5, 5,... Is the cooling per unit time discharged from the specifications of the cooling device 20, that is, the injection nozzles 4, 4. It can be decided according to various requirements represented by the amount of water.

  Moreover, in the said description regarding the cooling device 20 of this invention, although the form with which the two metal plates 6 and 6 were provided was illustrated, the cooling device of this invention concerning 2nd Embodiment is not limited to the said form. It is also possible to adopt a form in which three or more metal plates 6, 6,. If three or more metal plates 6, 6,... And the metal plates 5, 5,... Are joined, the rigidity of the metal plates 5, 5,. It is possible to further improve the effect of obstructing the flow of the cooling water toward.

  Further, in the cooling device 20 of the present invention, if the longitudinal direction of the metal plates 6, 6 is provided on the upper surface of the header portion 3 in a form that intersects with the traveling direction of the steel plate 1, the arrangement form of the metal plates 6, 6. Is not particularly limited. As an arrangement form of the metal plates 6, 6, in addition to a form arranged perpendicularly to the upper surface of the header part 3, so as to project into a space sandwiched between the upper surfaces of the transport rolls 2, 2 and the lower surface of the steel plate 1, The form (tilt arrangement) etc. which are arrange | positioned at the upper surface of the header part 3 can be illustrated. By making the inclined arrangement, it is possible to increase the area of the lower surface of the steel plate 1 in contact with the cooling water accumulated on the upper surface of the header portion 3. Therefore, it is preferable that the metal plates 6 and 6 are inclinedly arranged from the viewpoint of easily improving the lower surface cooling ability of the steel plate 1.

  Further, in the cooling device 20 of the present invention, the integrally formed metal plates 5, 5,... And the metal plates 6, 6 may be arranged in a non-detachable form on the upper surface of the header portion 3. It may be arranged in a possible form. From the standpoint of facilitating improvement of work efficiency at the time of inspection of the cooling device 20, it is preferable that the cooling device 20 is arranged in a detachable form.

  Further, in the above description regarding the cooling device 20, the form in which the rectifying means (metal plates 5, 5,...) And the movement control means (metal plates 6, 6) are joined is illustrated. The cooling device is not limited to this form. However, from the standpoint of improving the rigidity of the rectifying means so as to easily suppress the supercooling at the end in the width direction of the steel sheet, it is preferable that the rectifying means and the movement suppressing means are joined.

  In the lower surface cooling apparatus for steel sheets of the present invention, the arrangement form of the injection nozzles arranged in the header portion is not particularly limited, but from the viewpoint of easily improving the lower surface cooling ability of the steel sheets, the injection nozzles are provided. It is preferable to arrange them in a staggered manner.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

  Using the cooling device 10 disposed between the rolls 2 and 2 having a diameter of 400 mm (roll interval 750 mm), the effects of the metal plates 5, 5,. The cooling device 10 used for verification simulates an actual machine, and is a device that cools the lower surface of the test steel plate 1 installed on the movable carriage that passes above the cooling device 10. The test steel plate 1 is provided with a thermocouple at a position 1.5 mm from the lower surface (plate thickness is about 9 mm at a position 1.5 mm from the lower surface). The cooling device 10 is provided with a plurality of jet nozzles 4, 4,... Arranged in a staggered manner in the header portion 3, so that cooling water can be discharged toward the steel plate 1 passing above. ing.

The test was performed under the condition that the distance between the header portion 3 and the lower surface of the steel plate 1 was 50 mm, and the amount of cooling water jetted from the header portion 3 was 2500 L / m ² / min. When this amount of water is used, a water film can be formed between the header portion 3 and the lower surface of the steel plate 1.

  The cooling device 10 (hereinafter referred to as “cooling device according to the embodiment”) in which the lower surface of the steel plate 1 that is moved at 0.1 m / sec and heated to 800 ° C. is provided with the metal plates 5, 5,. ) And a cooling device that does not include the metal plates 5, 5,... (Hereinafter sometimes referred to as “cooling device according to comparative example”), and after cooling for about 7 seconds, The lower surface temperature of the steel plate 1 was measured. As a result, the temperature drop at the edge in the width direction of the lower surface of the steel plate cooled using the cooling device according to the comparative example was about 255 ° C., whereas the width of the lower surface of the steel plate cooled using the cooling device according to the example was used. The temperature drop at the end of the direction was about 230 ° C. That is, when the rectifying means is not used, overcooling of 25 ° C. occurs after cooling for about 7 seconds, and according to the cooling device (cooling apparatus of the present invention) according to the embodiment including the rectifying means, the width of the steel plate It was confirmed that supercooling at the direction end can be suppressed.

  Separately from this, the flow rate of the cooling water in the width direction of the steel sheet was measured. As a result, when the lower surface of the steel sheet 1 was cooled using the cooling device according to the comparative example, the flow velocity at the width end was about 1.0 m / sec, whereas the cooling device according to the example was When the lower surface of the steel plate 1 was cooled by using it, the flow velocity was approximately 0 m / sec. From the above, it can be presumed that there is a correlation between the cooling water moving in the width direction of the steel sheet and the supercooling at the end in the width direction of the steel sheet. That is, according to the present invention, it is possible to reduce the supercooling at the end in the width direction of the steel sheet by preventing the movement of the cooling water in the width direction of the steel sheet by the rectifying means.

It is a conceptual diagram which shows the form example of the cooling device concerning 1st Embodiment. It is a conceptual diagram which shows the positional relationship of the cooling device concerning 1st Embodiment, a steel plate, and a conveyance roll. It is a conceptual diagram which shows the form example of the cooling device concerning 2nd Embodiment. It is a conceptual diagram which shows the positional relationship of the cooling device concerning 2nd Embodiment, a steel plate, and a conveyance roll.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steel plate 2 ... Conveyance roll 3 ... Header part 4 ... Injection nozzle 5 ... Metal plate (rectifying means)
6. Metal plate (movement restraining means)
10, 20 ... Steel plate bottom surface cooling device

Claims (2)

A header portion arranged between a plurality of transport rolls arranged at intervals in the traveling direction of the steel plate, and a plurality of injection nozzles arranged in the header portion,
The lower surface of the steel sheet conveyed on the conveyance roll is cooled by the cooling medium discharged from the injection nozzle,
On the upper surface of the header portion, the discharged cooling medium is prevented from moving in the width direction of the steel sheet, and the discharged cooling medium is not prevented from moving in the traveling direction of the steel sheet. Rectifying means are provided,
The rectifying means is provided between a horizontal plane passing through the axes of the plurality of transport rolls and a lower surface of the steel plate, and further, the discharged cooling medium is on the upper surface of the header portion in the traveling direction of the steel plate. An apparatus for cooling the lower surface of a steel sheet , comprising movement control means for preventing movement of the steel sheet , wherein the height of the movement control means is lower than the height of the rectifying means . The steel sheet lower surface cooling apparatus according to claim 1, wherein the rectifying means and the movement control means are joined .

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