JP4779749B2 - Steel plate cooling method and cooling equipment - Google Patents

Description

  The present invention relates to a method for cooling a steel sheet and a cooling facility.

  In the process of manufacturing steel sheets by hot rolling, it is common to supply cooling water or air cooling to control the rolling temperature. Recently, however, the structure has been refined by obtaining a high cooling rate. The development of technology to increase the strength of steel sheets is thriving.

  For example, there is a technique described in Patent Document 1 as a technique for cooling a steel sheet by supplying cooling water. This is to raise and lower a slit nozzle unit that sprays cooling water in the direction of steel sheet conveyance, and it is said that a wide range of cooling rates can be secured by using it together with a separately provided laminar nozzle and spray nozzle. Yes.

  Moreover, there exists a technique described in patent document 2 as another technique which cools a steel plate by supplying cooling water. This is because the header having slit-like nozzles is inclined to face each other and the film-like cooling water is sprayed, and the partition plate is provided to fill the cooling water between the steel plate and the partition plate to obtain a high cooling rate. Yes.

  However, the techniques described in Patent Documents 1 and 2 have major problems in ensuring cooling uniformity and equipment costs.

  That is, in the technique described in Patent Document 1, the slit nozzle unit must be brought close to the steel plate, and when the steel plate with the tip or tail end warped is cooled, the steel plate collides with the slit nozzle unit, May be damaged, or the steel plate may not be able to move, causing the production line to stop or the yield to decrease. Therefore, it is conceivable that when the tip and tail ends pass, the lifting mechanism is operated to retract the slit nozzle unit upward. In this case, the leading and trailing ends are not sufficiently cooled, and the desired material is obtained. It becomes impossible. Furthermore, there is a problem that the equipment cost for providing the lifting mechanism is increased.

  In the technique described in Patent Document 2, the cooling water is not filled between the steel plate and the partition plate unless the nozzle is brought close to the steel plate. When the nozzle is brought close to the steel plate, similarly to the technique described in Patent Document 1, inconvenience occurs when cooling the steel plate with the tip and tail ends warped.

  Furthermore, in the techniques described in Patent Documents 1 and 2, it is assumed that a slit-like nozzle is used. However, if the jet outlet is not always maintained in a clean state, the cooling water does not form a film. For example, when a foreign substance adheres to the jet nozzle of the slit nozzle and becomes clogged, the cooling water film is broken. Moreover, in order to keep the cooling water in the injection region (in the cooling region) (drain water), it must be injected at a high pressure. However, when the film-like cooling water is injected at a high pressure, the balance of the injection pressure is poor. Thus, there was a problem that the cooling water film was easily broken. If the cooling water film is not formed well, the cooling water leaks in the upstream or downstream direction of the injection region, and there is a problem that it stays on the steel plate, partially cools the steel plate, and uneven temperature occurs. There is a technique for eliminating the cooling water staying on the upper surface of the steel plate by side spraying or the like. However, when the amount of cooling water is large, it cannot be completely eliminated, and there is a problem that temperature unevenness is caused.

  In order to solve the above problems, the present applicant has proposed a new steel plate cooling technique in Japanese Patent Application Nos. 2005-249055 (Unpublished Application 1) and 2005-249059 (Unpublished Application 2). is doing.

  That is, using a header having a nozzle group for injecting rod-shaped cooling water at a predetermined injection angle (deflection angle) with respect to the upper surface of the steel plate, in the unpublished application 1, a pair of headers are arranged in the steel plate conveyance direction, The cooling water sprayed from each header is opposed to each other at a predetermined interval on the steel plate in the steel plate conveyance direction. Further, in the unpublished application 2, one header is arranged at a predetermined interval from the rolling roll in the conveying direction of the steel sheet, and the cooling water sprayed from the header is blocked by the rolling roll.

  As a result, the supplied rod-shaped cooling water itself dams up the stagnant cooling water on the steel plate and appropriately drains it, so that a stable cooling region can be obtained and the steel plate can be cooled uniformly. is there.

Incidentally, the rod-shaped cooling water refers to cooling water ejected from a circular (including elliptical or polygonal) nozzle outlet.
JP-A-62-260022 JP 59-144513 A

  However, in the above-mentioned unpublished application 1 or unpublished application 2 or the like, when the speed of the rod-shaped cooling water sprayed from the header is fast, for example, 10 m / s or more, the cooling water is a water film (residual water). After collision with the film), it scatters upward. If this scattered cooling water falls again on the stagnant water film, there is no problem, but if it is scattered obliquely upward and dropped onto the rod-shaped cooling water, the dropped scattered cooling water may leak from the gap between the rod-shaped cooling water bundles. I understood that.

In particular, when the distance between the positions where the rod-shaped cooling water sprayed opposite to each other collides with the steel sheet (the length of the staying zone) is within 200 mm, the cooling water that scatters and falls is kept in that cooling zone. The problem that it becomes impossible to occur occurs remarkably. For example, in the case of an injection angle (deflection angle) of 30 °, an injection position height of 1000 mm, and a cooling water amount of 10 m ³ / min · m ² , the problem occurs when the staying zone length is within 200 mm.

  The present invention has been made in view of the circumstances as described above, and when the steel plate is cooled to the target temperature by injecting bar-shaped cooling water at a predetermined injection angle onto the upper surface of the steel plate, the residence on the steel plate A cooling method for a steel sheet that can be accurately drained from the scattered cooling water that has collided with the water film and scattered and then dropped onto the steel sheet, thereby enabling the steel sheet to be uniformly and stably cooled at a high cooling rate. And it aims at providing cooling equipment.

  In order to solve the above problems, the present invention has the following features.

[1] With respect to the upper surface of the steel plate, a first nozzle group for injecting the rod-shaped cooling water at an inclination angle of 30 to 60 ° with respect to the steel plate conveyance direction is disposed, and from the jet line of the cooling water to the outermost steel plate conveyance direction. The second nozzle group for injecting rod-shaped cooling water to the upper surface of the steel sheet from the outer side in the steel sheet conveying direction is disposed, and the cooling water on the outermost side in the steel sheet conveying direction that is injected from the first nozzle group collides with the steel sheet. A steel plate cooling method characterized by injecting rod-shaped cooling water from the second nozzle group onto the upper surface of the steel plate outside the steel plate conveyance direction .

  [2] The method for cooling a steel plate according to [1], wherein a group of nozzles for injecting rod-shaped cooling water is disposed so as to face each other in a conveying direction of the steel plate.

  [3] The above-mentioned [1] or [2], wherein the second nozzle group includes two or more nozzles arranged in the conveying direction of the steel plate and jets rod-shaped cooling water from the nozzle at a speed of 10 m / s or more. 2] The cooling method of the steel plate as described in 2].

[4] A first nozzle group for injecting rod-shaped cooling water at an inclination angle of 30 to 60 ° with respect to the steel sheet conveyance direction is disposed on the upper surface of the steel sheet, and the outermost cooling water to be injected collides with the steel sheet. a steel plate conveyance direction outward from the point to, the upper surface of the steel plate, the second nozzle group for ejecting the rod-like cooling water are arranged, rod-like cooling water to the upper surface of the steel plate conveyance direction outside of the steel plate than the point of the collision A steel sheet cooling facility characterized by spraying water.

  [5] The steel sheet cooling equipment according to [4], wherein the nozzle group injects the rod-shaped cooling water so as to face each other in the conveying direction of the steel sheet.

  [6] The [4] or [4], wherein the second nozzle group includes two or more rows of nozzles arranged in a conveying direction of the steel plate and jets rod-shaped cooling water from the nozzle at a speed of 10 m / s or more. 5].

  By using the present invention, the scattered cooling water can be drained accurately, whereby the steel sheet can be uniformly and stably cooled to the target temperature at a high cooling rate. As a result, it becomes possible to manufacture a high-quality steel sheet.

  Embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an explanatory diagram of a steel sheet cooling facility according to the first embodiment of the present invention.

  The cooling facility according to this embodiment is a passing-type cooling facility installed on a hot rolling line for steel plates, and includes a cooling unit 20. The cooling unit 20 is disposed in the vicinity of the rolling roll 17, and an upper header (first upper header 21, second upper header 25) for supplying bar-shaped cooling water toward the upper surface of the steel plate 10, A lower header 51 for supplying cooling water from between the table rollers 13 toward the lower surface of the steel plate 10 is provided.

  The first upper header 21 has a plurality of rows (here, six rows) of circular tube nozzles (first upper nozzles) 22 in the steel plate conveyance direction, and the second upper header 25 has a plurality of rows (here, the steel plate conveyance direction). (3 rows) of circular pipe nozzles (second upper nozzles) 26 are respectively attached, and the rod-shaped cooling water 23 is supplied from the first upper nozzle 22 toward the rolling roll 17 at a predetermined injection angle (deflection angle) θ1. The rod-shaped cooling water 27 is supplied from the second upper nozzle 26 toward the rolling roll 17 at a predetermined spray angle (deflection angle) θ2.

  At this time, the first upper header 21 and the second upper header 25 are arranged so that the injection line of the rod-shaped cooling water 23 from the first upper nozzle 22 and the injection line of the rod-shaped cooling water 27 from the second upper nozzle 26 do not intersect. And the injection angles θ1 and θ2 are adjusted.

  By configuring as described above, the cooling water 23 supplied from the first upper nozzle 22 is blocked by the rolling roll 17 and the rod-shaped cooling water 23 itself on the steel plate 10, and the stagnant cooling water 28 on the steel plate 10. The scattered cooling water 29 that collides with the water film (retained water film) and scatters and leaks from the gap between the bundles of the rod-shaped cooling water 23 and the cooling water 27 supplied from the second upper nozzle 26 are on the steel plate 10. It is blocked by the rod-shaped cooling water 27.

  Thereby, from the position where the rolling roll 17 and the steel plate 10 are in contact to the position where the cooling water from the circular tube nozzle in the outermost row of the second upper header 25 collides with the steel plate 10 is the cooling region. A water film of the staying cooling water 28 is stably formed on the steel plate 10, and a stable cooling region is obtained.

  The distance from the position where the rolling roll 17 and the steel plate 10 are in contact to the position where the rod-shaped cooling water sprayed from the circular tube nozzle in the innermost row of the first upper header 21 collides with the steel plate 10 is the length of the primary staying zone. L1, from the position where the rod-shaped cooling water sprayed from the outermost tube nozzle of the first upper header 21 collides with the steel plate 10, was ejected from the innermost tube nozzle of the second upper header 25. If the distance to the position where the rod-shaped cooling water collides with the steel plate 10 is referred to as the secondary staying area length L2, if the secondary staying area length L2 is set to 1 m or less, it will leak from the gap between the bundles of the rod-shaped cooling water 23. The scattered cooling water 29 that has come out can be dropped onto the stagnant cooling water in the secondary stagnant zone, and the rate at which the stagnant cooling water in the secondary stagnant zone cools the steel plate 10 is relatively small. Field where the tail passes in an unsteady state The way cold significantly change can be prevented.

  Incidentally, in this embodiment, the cooling water sprayed from the upper nozzle is not a film-like cooling water using, for example, a slit nozzle but a rod-like cooling water. This is because the power to dam the cooling water is great. In addition, when the film-like cooling water is injected obliquely, the water film near the steel sheet becomes thin and becomes more fragile as the distance from the steel sheet to the nozzle increases.

  FIG. 3 shows an arrangement example of the first upper nozzles (first upper nozzle group) 22 attached to the first upper header 21. As described above, six rows of circular tube nozzles are arranged in the steel plate conveyance direction. FIG. 3A shows an arrangement in which six rows are provided in the steel plate conveyance direction with an interval between nozzles adjacent in the steel plate conveyance direction being 40 mm, and FIG. 3B is an interval between nozzles adjacent in the steel plate conveyance direction is 20 mm. An example (substantially 6 rows) in which two rows are provided in the transport direction is shown. And in the board width direction, it attaches so that cooling water can be supplied to the full width of the steel plate which passes.

  In addition, the second upper nozzles (second upper nozzle group) 26 attached to the second upper header 25 are also arranged in three rows in the same manner as described above.

  Here, the first upper header 21 and the second upper header 25 are provided separately, but one header in which they are integrated may be provided, and a circular tube nozzle may be arranged thereon.

  On the other hand, with respect to the lower header 51, a circular pipe nozzle 52 is attached as a lower nozzle, and the rod-shaped cooling water 53 is jetted from the gap between the table rollers 13 to supply the cooling water to the entire width of the passing steel plate 10. It has become.

  This embodiment will be described in further detail below.

  In this embodiment, the main roles of the rod-like cooling water 23 from the first upper nozzle 22 and the rod-like cooling water 27 from the second upper nozzle 26 are to secure the cooling capacity and to secure the cooling water damming force, respectively.

  The rod-shaped cooling water 23 sprayed from the first upper nozzle 22 has a cooling function and acts like a wall for damming the cooling water that is about to leak to the outside of the steel sheet conveyance direction (the direction opposite to the rolling roll 17). For this purpose, the number of nozzle rows of the first upper nozzles 22 is better, and the faster the injection speed, the better. Specifically, if the nozzle rows are at least 4 rows in the steel plate conveyance direction and the injection speed is 10 m / s or more, the cooling capability is sufficient and the cooling water is dammed.

  In addition, the rod-shaped cooling water 27 sprayed from the second upper nozzle 26 functions as a wall that dams up the cooling water that is about to leak to the outside of the steel plate conveyance direction (the direction opposite to the rolling roll 17) and also has a cooling capacity. In order to give it, it is preferable that the injection speed is as high as possible, and it is desirable that the injection speed of the rod-shaped cooling water 27 is equal to or higher than the injection speed of the rod-shaped cooling water 23. Further, it is sufficient that the nozzle row is more than half the number of rows of the first upper nozzles 22. If the amount is too large, there is a possibility that the drainage will be deteriorated by the scattered cooling water. Specifically, if the nozzle rows are at least two rows in the conveying direction of the steel plate and the injection speed is 10 m / s or more, the force for blocking the cooling water is sufficient.

  The position where the rod-shaped cooling water sprayed from the innermost row of the second upper nozzle 27 collides with the steel plate 10 is the position where the rod-shaped cooling water sprayed from the outermost row of the first upper nozzle 22 collides with the steel plate 10. It needs to be outside. This is because if it is inside, it will interfere with the rod-shaped cooling water from the first upper nozzle 22.

  Furthermore, the position where the rod-shaped cooling water sprayed from the innermost row of the second upper nozzle 27 collides with the steel sheet is the position of the outermost spray nozzle of the first upper nozzle 22 (position projected perpendicularly to the steel sheet surface). It is preferable to be outside. This is because the scattered cooling water 29 leaking from the gap between the bundles of the rod-shaped cooling water 23 also leaks from the gap between the bundles of the rod-shaped cooling water 27 if it is inside. However, if the interval (that is, the secondary staying area length L2) is too wide, the cooling staying unevenness occurs due to the scattered cooling water 29 leaking from the gap between the bundles of the rod-shaped cooling water 23. L2 is preferably at most 1 m at most.

  In order to prevent the circular tube nozzle from clogging and to ensure the injection speed of the rod-shaped cooling water, the inner diameter of the circular tube nozzle may be in the range of 3 to 8 mm. Further, in order to prevent the stagnant cooling water on the steel plate from flowing out from the gap between the rod-shaped cooling water, the interval between adjacent nozzles on the imaginary line drawn in the plate width direction should be within 10 times the nozzle inner diameter. Good.

  Moreover, it is preferable that the injection angle θ1 of the first upper nozzle 22 is 30 ° to 60 °. This is because, when the injection angle θ1 is smaller than 30 °, the vertical velocity component of the rod-shaped cooling water 23 becomes small, the collision with the steel plate 10 becomes weak, and the cooling capacity decreases. On the other hand, if the injection angle θ1 is larger than 60 °, the speed component in the steel plate conveyance direction of the rod-shaped cooling water 23 becomes small, the force for blocking the cooling water on the steel plate becomes weak, and the cooling water flows out of the cooling region and becomes large. This is because temperature unevenness occurs. The injection angle θ1 and the injection angle θ2 of the second upper nozzle are not necessarily equal. What is necessary is just to set suitably the angle which can drain completely.

  Further, in order to prevent the first upper nozzle 22 and the second upper nozzle 26 from being damaged by warpage of the steel plate 10, the position of the tip (injection port) of each nozzle is moved from the conveyance line (table roller) of the steel plate. It is preferable to separate them, but if they are separated too much, the rod-shaped cooling water will disperse and will not be rod-shaped and will have no function of blocking the cooling water, so the distance between the nozzle tip and the conveying line is preferably 500 mm to 1800 mm.

Furthermore, this embodiment is applied to the cooling of the control rolled material of the thick steel plate, and the control rolled material is cooled with water while passing through the rolling, so that it is allowed to cool to a predetermined controlled rolling start temperature and wait for cooling. In order to solve this problem, it is preferable to set the water density of the rod-shaped cooling water to 4 m ³ / m ² min or more. The staying cooling water 28 is formed by being blocked by the rod-like cooling waters 23 and 27 to be supplied. At this time, when the water density increases, the amount of the accumulated cooling water that can be dammed up increases, and the amount of the cooling water discharged from the end of the plate width and the amount of the supplied cooling water are balanced so that the accumulated cooling water is kept constant. The In the case of thick steel rice, the general plate width is ^{2 to 5} m, and if the cooling water is supplied at a water density of 4 m ³ / m ² min or more, the staying cooling water 28 can be kept constant at these plate widths. Thus, a desired temperature drop amount can be obtained while passing the thick steel plate being rolled.

And the control rolling material which eliminates the waiting for cooling increases, so that water quantity density is enlarged 4 m < ³ > / m < ² > min or more. For example, if the water density is small, the waiting for cooling can be solved only with the control rolled material with a thin plate thickness. However, if the water density is increased, the waiting for cooling can be eliminated even with the control rolled material having a certain thickness. However, the effect of shortening the cooling waiting time for increasing the amount of water gradually decreases as the water density increases, so the water density takes into account the effect of shortening the cooling waiting time and the equipment cost, It is preferable to determine.

  In addition, in the above, there is no special limitation in the cooling method of the lower surface of a steel plate, The method generally used can be applied. However, the upper and lower cooling capacities of the steel plates should be approximately the same and be cooled uniformly. This is because if the cooling is not performed uniformly, the steel sheet will bend or warp, and the product direct rate will decrease.

  By applying the cooling equipment and the cooling method as described above to a hot rolling line for thick steel plates and thin steel rice, the steel plates can be cooled uniformly and stably to a target temperature at a high cooling rate. As a result, it becomes possible to manufacture a high-quality steel sheet.

  In the above, an intermediate header may be provided between the rolling roll 17 and the upper header (the first upper header 21 and the second upper header 25) to increase the cooling capacity, and the number may be any number. .

(Second Embodiment)
FIG. 2 is an explanatory diagram of a steel sheet cooling facility according to the second embodiment of the present invention.
The cooling facility according to this embodiment is a passing-type cooling facility installed on a hot rolling line for steel plates, and includes a cooling unit 30. This cooling unit 30 is configured by arranging the cooling units 20 as shown in FIG. 1 so as to face each other in the steel plate conveyance direction. That is, an upper header (first upper header 31 and second upper header 35) for supplying rod-shaped cooling water toward the upper surface of the steel plate 10, and toward the upper surface of the steel plate 10 so as to face the steel plate conveying direction. An upper header (third upper header 41, fourth upper header 45) for supplying rod-shaped cooling water and a lower header (not shown) for supplying cooling water from between the table rollers toward the lower surface of the steel plate 10. )have.

  The first upper header 31 has a plurality of rows (six here) of circular tube nozzles (first upper nozzles) 32 in the steel plate conveyance direction, and the second upper header 35 has a plurality of rows (here, steel plate conveyance direction). (3 rows) of circular pipe nozzles (second upper nozzles) 36 are respectively attached, and rod-shaped cooling water at a predetermined injection angle (deflection angle) θ1 from the first upper nozzle 32 toward the third upper header 41. 33 is supplied, and the rod-shaped cooling water 37 is supplied from the second upper nozzle 36 toward the third upper header 41 at a predetermined injection angle (deflection angle) θ2.

  Similarly, the third upper header 41 has a plurality of rows (here, six rows) of circular tube nozzles (third upper nozzle) 42 in the steel plate conveyance direction, and the fourth upper header 45 has a plurality of rows (here). In this case, three rows of circular tube nozzles (fourth upper nozzles) 46 are respectively attached, and rod-shaped cooling is performed at a predetermined injection angle (deflection angle) θ1 from the third upper nozzle 42 toward the first upper header 31. Water 43 is supplied, and rod-shaped cooling water 47 is supplied from the fourth upper nozzle 46 toward the first upper header 31 at a predetermined injection angle (deflection angle) θ2.

  At this time, the injection line of the rod-shaped cooling water 33 from the first upper nozzle 32 and the injection line of the rod-shaped cooling water 43 from the third upper nozzle 42 are not crossed, and the rod-shaped cooling from the first upper nozzle 32 is avoided. The injection line of water 33 and the injection line of rod-shaped cooling water 37 from the second upper nozzle 36 do not intersect, and the injection line of rod-shaped cooling water 43 from the third upper nozzle 42 and the rod shape from the fourth upper nozzle 46 The intervals between the upper headers (the first upper header 31, the second upper header 35, the third upper header 41, the fourth upper header 45) and the injection angles θ1 and θ2 are set so that the injection lines of the cooling water 47 do not intersect. It has been adjusted.

  Other points are the same as those described in the first embodiment.

  By configuring as described above, the cooling water 33 and 43 supplied from the first upper nozzle 32 and the third upper nozzle 42 are blocked by the rod-shaped cooling water 33 and the rod-shaped cooling water 43 on the steel plate 10, The cooling water supplied from the second upper nozzle 36 and the scattered cooling water 39 that collides with the water film (retaining water film) of the retained cooling water 38 on the steel plate 10 and scatters and leaks from the gap between the bundles of the rod-shaped cooling water 33. The water 37 is blocked by the rod-shaped cooling water 37 on the steel plate 10, collides with the water film (retained water film) of the staying cooling water 38 on the steel plate 10, scatters, and leaks from the gap between the bundles of the rod-shaped cooling water 43. The scattered cooling water 49 and the cooling water 47 supplied from the fourth upper nozzle 46 are blocked by the rod-shaped cooling water 47 on the steel plate 10.

  Thereby, from the position where the cooling water from the outermost row of circular pipe nozzles of the second upper header 35 collides with the steel plate 10, the cooling water from the outermost row of circular pipe nozzles of the fourth upper header 45 is changed to the steel plate. The position up to the position where it collides with 10 is the cooling region, and the water film of the staying cooling water 38 is stably formed on the steel plate 10 between the cooling regions.

  By applying the cooling equipment and the cooling method as described above to a hot rolling line for thick steel plates and thin steel rice, the steel plates can be cooled uniformly and stably to a target temperature at a high cooling rate. As a result, it becomes possible to manufacture a high-quality steel sheet.

  In the above, an intermediate header is provided between the opposing upper headers (the first upper header 31 and the third upper header 41), and the cooling capacity between the opposing upper headers can be increased. There may be.

  1 and 2 may be used singly or in plural, and FIG. 1 and FIG. 2 may be used together in one steel plate production line.

  Examples of the present invention are described below.

  FIG. 4 is a diagram showing a hot rolling line for thick steel plates used in this example and a conveyance pattern there. The thick steel plate hot rolling line includes a heating furnace 11, a reversible rolling mill 12, a first cooling facility 14, a hot leveler 15, and a second cooling facility 16.

  And conveyance pattern A performs accelerated cooling after finish rolling, and after carrying out rough rolling and finish rolling the slab extracted from heating furnace 11 by reversible rolling machine 12, and making plate thickness 25mm, Through the hot leveler 15, the second cooling device 16 performs accelerated cooling with a temperature drop of 150 ° C.

  Moreover, the conveyance pattern B performs temperature adjustment cooling before controlled rolling, and after the slab extracted from the heating furnace 11 is rough-rolled by the reversible rolling machine 12 to have a plate thickness of 60 mm, the first cooling is performed. The apparatus 14 performs the adjustment cooling with a temperature drop of 80 ° C., and then performs low temperature finish rolling, that is, controlled rolling. In the final three passes, controlled rolling is performed at a relatively low rolling temperature. Therefore, the adjustment cooling is performed when the plate thickness is reduced to 28 mm in the previous four passes.

  As Example 1 of the present invention, one unit of the cooling unit 20 shown in FIG. 1 is arranged as the first cooling equipment 14 on the exit side of the rolling mill 12, and six units of the cooling unit shown in FIG. 2 are installed in the second cooling equipment 16. The conveyance pattern A and the conveyance pattern B were conveyed and cooled. Cooling of the lower surface of the steel plate was performed using a known technique. At that time, for the upper nozzles 22, 26, 32, 36, 46, 42, the height of the nozzle tip is 1 m from the table roller 13, and the nozzle arrangement shown in FIG. The injection angles θ1 and θ2 of the rod-shaped cooling water were 45 ° and the injection speed was 12 m / s.

  As Example 2 of the present invention, 2 units of the cooling unit 30 shown in FIG. 2 were installed in the first cooling facility 14 and 8 units were installed in the second cooling facility 16 to transport and cool the transport pattern A and the transport pattern B. . Cooling of the lower surface of the steel plate was performed using a known technique. At that time, for the upper nozzles 32, 36, 42 and 46, the height of the nozzle tip is 1 m from the table roller 13, the nozzle inner diameter is 6 mm in the nozzle arrangement shown in FIG. The injection angle θ1 was 45 °, θ2 was 30 °, and the injection speed was 12 m / s. The distance between the positions where the rod-shaped cooling water from the innermost nozzle of the first upper nozzle 32 and the rod-shaped cooling water from the innermost nozzle of the third upper nozzle 42 collide with the steel plate 10 (that is, the primary retention area). The length L1) was 0 mm.

  On the other hand, as Comparative Example 1, the first cooling facility 14 and the second cooling facility 16 were changed to conventional conventional shower cooling devices to transport and cool the transport pattern A and the transport pattern B.

  Further, as Comparative Example 2, the first cooling equipment 14 and the second cooling equipment 16 are the cooling devices described in Patent Document 2 in which the film-like cooling water is jetted so as to face each other. Transport and cooling were performed.

  And in each case, after cooling (after fully ripening), the steel plate width direction temperature was continuously measured using the radiation thermometer, and the temperature distribution of the steel plate upper surface was investigated. The temperature variation (difference between the highest temperature and the lowest temperature) in the stationary part excluding the cutting edge, the tail edge, and the width direction plate edge was defined as temperature unevenness and compared. The magnitude of the temperature unevenness almost corresponded to the variation in mechanical properties of the product such as tensile strength. The production efficiency and the yield were compared on the basis of Comparative Example 1.

  The results are shown in Table 1.

  First, in Comparative Example 1, shower cooling is performed, and due to the influence of cooling water that remains unstable on the steel plate, temperature unevenness is 80 ° C. in the conveyance pattern A (accelerated cooling after finish rolling), and the conveyance pattern B (controlled rolling). In the previous temperature-controlled cooling), the temperature was 40 ° C., and the product had a large variation in strength.

  Next, in Comparative Example 2, since the nozzle had to be brought close to the steel plate, the equipment might be damaged when the warpage of the steel plate occurred. Since the steel plate that collided with the equipment did not become a product, the yield of the product decreased compared to Comparative Example 1. In addition, since it took a considerable amount of time to repair the damaged equipment, the production efficiency also declined. Further, since the film-like cooling water is supplied, foreign matter adheres to the nozzle outlet and the film-like cooling water is not formed, and the cooling water may not be dammed in the injection region (in the cooling region). Therefore, due to the influence of the cooling water that stays unstable on the steel sheet, the temperature unevenness becomes 80 ° C. in the conveyance pattern A (accelerated cooling after finish rolling), and 40 ° C. in the conveyance pattern B (temperature adjustment cooling before controlled rolling). The variation in product strength was also large.

  On the other hand, in the present invention examples 1 and 2, the supplied rod-shaped cooling water itself can dam the staying cooling water on the steel plate and drain water accurately, and a stable cooling region was obtained. As a result, the temperature unevenness was suppressed to an extremely low value of 8 to 15 ° C., the steel plate could be uniformly cooled, and the strength variation was small and a high quality steel plate could be produced.

  Also, in Examples 1 and 2 of the present invention, the height of the tip of the nozzle was increased to 1 m, so that the equipment was not damaged even if the steel plate warped, the yield was not reduced by trouble, and the production efficiency was improved. did.

  Furthermore, in the present invention example 1, since the rolling roll could be cooled by the supplied cooling water, the equipment for cooling the rolling roll can be made simpler than usual and the equipment cost can be suppressed. I was able to.

  From the above results, the effectiveness of the present invention was confirmed.

It is explanatory drawing of the cooling equipment which concerns on the 1st Embodiment of this invention. It is explanatory drawing of the cooling equipment which concerns on the 2nd Embodiment of this invention. It is the figure which showed the nozzle arrangement example of the upper header in embodiment of this invention. It is explanatory drawing of the hot rolling line and conveyance pattern of the steel plate in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Steel plate 11 Heating furnace 12 Reversible rolling mill 13 Table roller 14 1st cooling equipment 15 Hot leveler 16 2nd cooling equipment 17 Rolling roll 20 Cooling unit 21 1st upper header 22 1st upper nozzle 23 Rod-shaped cooling water 25 2nd upper header 26 Second upper nozzle 27 Rod-shaped cooling water 28 Stagnating cooling water 29 Spattering cooling water 30 Cooling unit 31 First upper header 32 First upper nozzle 33 Rod-shaped cooling water 35 Second upper header 36 Second upper nozzle 37 Rod-shaped cooling water 38 Retention Cooling water 39 Spattering cooling water 41 Third upper header 42 Third upper nozzle 43 Rod cooling water 45 Fourth upper header 46 Fourth upper nozzle 47 Rod cooling water 49 Scattering cooling water 51 Lower header 52 Lower nozzle 53 Rod cooling water

Claims (6)

The upper surface of the steel plate, as well as placing a first nozzle group for ejecting the rod-like cooling water dip 30 to 60 ° with respect to the steel plate conveyance direction, most steel conveying direction outside of the steel plate conveyance than the injection line of the cooling water jetting A second nozzle group for injecting rod-shaped cooling water is disposed on the upper surface of the steel sheet from the outside in the direction , and the steel sheet is located at a position farther from the point where the cooling water on the outermost side in the steel sheet conveying direction to be injected from the first nozzle group collides with the steel sheet. A method for cooling a steel sheet, comprising: injecting bar-shaped cooling water from the second nozzle group onto the upper surface of the steel sheet on the outer side in the conveying direction .   The method for cooling a steel sheet according to claim 1, wherein a nozzle group for injecting rod-shaped cooling water is disposed so as to face each other in the conveying direction of the steel sheet.   The steel plate according to claim 1 or 2, wherein the second nozzle group has two or more rows of nozzles arranged in a conveying direction of the steel plate and jets rod-shaped cooling water from the nozzle at a speed of 10 m / s or more. Cooling method. From the point where the first nozzle group for injecting rod-shaped cooling water at an inclination angle of 30 to 60 ° with respect to the steel plate conveyance direction is disposed on the upper surface of the steel plate, and the cooling water outside the steel plate conveyance direction to be injected collides with the steel plate. from even the steel plate conveyance direction outward with respect to the upper surface of the steel plate, the second nozzle group for ejecting the rod-like cooling water are arranged to inject the rod-like cooling water to the upper surface of the steel plate conveyance direction outside of the steel plate than the point of the collision Steel sheet cooling equipment characterized by that.   The said nozzle group sprays rod-shaped cooling water so that it may mutually oppose in the conveyance direction of a steel plate, The cooling equipment of the steel plate of Claim 4 characterized by the above-mentioned.   6. The steel plate according to claim 4, wherein the second nozzle group includes two or more rows of nozzles arranged in a conveying direction of the steel plate and jets rod-shaped cooling water from the nozzle at a speed of 10 m / s or more. Cooling equipment.

Images