JP2008100256A - Equipment and method for cooling steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide equipment and a method for cooling a steel sheet by which cooling water is supplied uniformly in the width direction even when a camber is generated on the steel sheet and the whole steel sheet is uniformly cooled in a hot-rolling line of the steel sheet. <P>SOLUTION: Both of nozzles 22 for supplying cooling water 23 onto the upper surface of the steel sheet and nozzles 32 for supplying cooling water 33 onto the back surface of the steel sheet are tilted to the outside in the width direction of the steel sheet. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  In a hot rolling line for steel plates (particularly thick steel plates), various cooling devices such as an acceleration cooling device and a control cooling device are used for the purpose of reducing alloy elements, improving material quality, and improving production efficiency. In these cooling methods for thick steel plates, cooling water is generally supplied to the upper and lower surfaces while transporting the thick steel plates on a transport roll. In any cooling device, uniform cooling is performed in the plate width direction and the transport direction. It is important to do.

  Therefore, for example, a cooling device as described in Patent Document 1 has been proposed. The cooling device described in Patent Document 1 is a cooling device in which a plurality of cooling units each composed of a pair of upper and lower steel plate restraining rolls are arranged in the conveying direction of the thick steel plate, on the exit side of the exit side restraint roll and the exit side restraint roll. Since the cooling water leaking from the gap between the roll and the steel plate cannot be completely removed with the provided air slit nozzle alone, a cooling header extending in the plate width direction is disposed on the exit side of the exit side restraining roll, and the header is thick. This is a cooling device that is opposed to the conveying direction of the steel sheet, and in which cooling liquid injection nozzles are inclinedly arranged with the injection ports facing in the opposite direction to the conveying direction.

  That is, in the cooling device described in Patent Document 1, in order to completely drain water on the exit side of the exit-side restraining roll, a large number of nozzles are arranged in the plate width direction, and the cooling water leaked by the ejected cooling water is forced. Then, the steel sheet is washed away in the width direction of the thick steel plate, and further compressed air is sprayed from the air slit nozzle to eliminate any residual water on the thick steel plate.

  However, at that time, if the water density in the cooling unit is increased, the water cannot be sufficiently drained, and the equipment must be enlarged in order to increase the drainage capacity. There is a risk of the steel plate colliding with the nozzle.

  Therefore, the present applicant has proposed a new steel plate cooling technique in Japanese Patent Application No. 2006-227404 (Unpublished Application 1).

  That is, as shown in a side view in FIG. 1 and a plan view in FIG. 2, an upper nozzle group 22 for injecting cooling water (rod-like cooling water) 23 at a predetermined injection angle (deflection angle) θ with respect to the upper surface of the steel plate 10 is provided. A pair of upper headers 21 are arranged in the steel plate conveying direction, and cooling waters 23a and 23b sprayed from the upper nozzle groups 22a and 22b of the upper headers 21a and 21b are placed at a predetermined interval on the steel plate in the steel plate conveying direction. While facing each other, the spray line seen from above has an angle (outward angle) α defined by an angle formed with the steel plate conveyance direction.

  As an example, in FIG. 2, the nozzles are installed so that the outward angle α of the cooling water 23 is constant and the positions where the cooling water 23 collides with the steel plate 10 (collision points) are equally spaced in the steel plate width direction. ing. At that time, in the vicinity of the center in the width direction of the steel sheet, a nozzle that inclines to the left and right in the width direction must be installed, so that the hole for attaching the nozzle can be machined to the left end of the width direction of the steel sheet. Inclined nozzle row (for example, a nozzle row having a jet velocity component in the upper direction in the upper headers 21a and 21b in FIG. 2) and a nozzle row to be tilted and ejected to the outer right end in the steel plate width direction (for example, in FIG. 2) In the upper headers 21a and 21b, nozzle rows having a jet velocity component in the downward direction are alternately shifted by a predetermined interval in the steel plate conveyance direction. Here, in the vicinity of the central portion in the width direction of the steel sheet, the injection line of the cooling water from the nozzle that inclines and injects the left end in the width direction of the steel sheet intersects the injection line of the cooling water from the nozzle that inclines and injects the right end of the steel sheet in the width direction. is doing.

As a result, in the unpublished application 1, the supplied cooling water 23 itself dams up the staying cooling water 24 on the steel plate 10 and drains it appropriately, and a stable cooling region is obtained. It can cool uniformly.
JP 60-206516 A

  However, in the unpublished application 1, if the cooling water 23 has a steel plate width direction component by injecting the upper nozzle 22 toward the outer side in the steel plate width direction, the drainage of the cooling water 23 is improved, but the upper warp, etc. When the height position of the steel plate 10 is changed by this, there is a problem that the collision point of the cooling water 23 moves in the steel plate width direction.

  Usually, in a hot rolling line, as shown in FIG. 3, due to the vertical imbalance of rolling, sometimes the top end of the steel plate 10 may warp, and in that case, there is no warp. The height position of the steel plate 10 changes between the steel plate steady portion and the warp generating portion where the warpage has occurred.

  Now, as shown in FIG. 4, when the position (collision point) where the cooling water (injection line) from the upper nozzle 22 collides with the upper surface of the steady portion of the steel plate 10 is defined as the collision point A, As shown in FIG. 4, the collision point of the cooling water from the upper nozzle 22 changes to the collision point B. At that time, the collision point B moves in the steel plate conveyance direction due to the influence of the depression angle θ, and at the same time, as shown in FIG. Will move to the side. Therefore, when the upper nozzle 22 is installed so that the collision points of the cooling water are equally spaced in the steel plate width direction with respect to the stationary part, the distance between the collision points is partially equal to the warp generation part. There will be places that are not spaced.

  Specifically, in FIG. 6, assuming that the distance W between the collision points A with respect to the steel plate 1 is equal, the collision point B with respect to the steel plate 2 moves by ΔW to the center side in the steel plate width direction from the collision point A. At that time, since the jetting is performed in the same direction except in the vicinity of the central portion in the steel plate width direction, each collision point moves ΔW in the same direction, so that the collision point interval is maintained at W. However, in the vicinity of the central portion in the width direction of the steel sheet, since the injection is performed in different directions, the collision points move by ΔW in the direction in which they approach each other, and the collision point interval becomes W−2ΔW and becomes narrower. .

  As a result, for the warp generation part, the cooling water supply amount at the upper surface of the central part in the steel sheet width direction is larger than that in other parts, and the central part in the steel sheet width direction is overcooled and uneven in the steel sheet width direction. Temperature distribution, and there is a possibility that a high-quality steel sheet cannot be manufactured.

  The present invention has been made in view of the circumstances as described above, and in the hot rolling line for steel sheets, even when warpage occurs in the steel sheet, the cooling water can be supplied uniformly in the width direction of the steel sheet, and the entire steel sheet is uniform. It is an object of the present invention to provide a steel plate cooling facility and a cooling facility method that can be cooled to each other.

  In order to solve the above-mentioned problems, the present inventors have intensively studied. As a nozzle for supplying cooling water to the lower surface of the steel plate, the width of the steel plate is similar to the nozzle for supplying cooling water to the upper surface of the steel plate. I came up with the idea of using a nozzle that was tilted outward. In other words, if a nozzle that is inclined outward in the steel sheet width direction is used for both the upper and lower surfaces of the steel sheet, the upper surface of the steel sheet has a narrower collision point interval at the center part in the steel sheet width direction and the cooling water supply amount increases. On the other hand, the lower surface of the steel plate has a larger collision point interval at the central portion in the width direction of the steel plate and the cooling water supply amount is reduced, so that they are offset and the steel plate can be cooled uniformly in the width direction. become able to.

  The present invention is based on the above concept and has the following features.

[1] A cooling facility used in a hot rolling line for steel plates,
The injection direction of at least some of the nozzles that supply cooling water to the upper surface of the steel plate and the injection direction of at least some of the nozzles that supply cooling water to the lower surface of the steel plate are respectively perpendicular to the vertical line. The steel sheet cooling equipment is characterized in that the steel sheet is inclined outward in the width direction of the steel sheet, and an area on the upper surface of the steel sheet intersects with a jet line of the cooling water projected onto a plane perpendicular to the conveying direction.

  [2] A straight line obtained by projecting an injection line of the cooling water onto a surface perpendicular to the conveying direction for each of the nozzle for supplying the cooling water to the upper surface of the steel plate and the nozzle for supplying the cooling water to the lower surface of the steel plate. And the vertical line is φ, and tan φ = 0 to 0.35 (preferably tan φ = 0.1 to 0.35).

  [3] The steel sheet cooling facility according to [1] or [2], wherein the cooling water is a rod-shaped cooling water.

[4] A cooling method used in a hot rolling line for steel plates,
The injection direction of at least some of the nozzles that supply cooling water to the upper surface of the steel plate and the injection direction of at least some of the nozzles that supply cooling water to the lower surface of the steel plate A method for cooling a steel sheet, wherein the steel sheet is tilted outward in the width direction of the steel sheet, and a region on the upper surface of the steel sheet where a jet of cooling water projected onto a plane perpendicular to the conveying direction intersects is formed.

  [5] A straight line and a vertical line in which an injection line is projected on a plane perpendicular to the conveying direction for each nozzle of the nozzle for supplying cooling water to the upper surface of the steel plate and the nozzle for supplying cooling water to the lower surface of the steel plate Is the angle formed by tan φ = 0 to 0.35 (preferably tan φ = 0.1 to 0.35). The method for cooling a steel sheet according to [4] above.

  [6] The method for cooling a steel sheet according to [4] or [5], wherein the cooling water is rod-shaped cooling water.

  By using the present invention, the entire steel sheet can be uniformly cooled even if the height position of the steel sheet being conveyed changes due to warpage or the like. As a result, a high quality steel plate can be manufactured.

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

  A basic configuration of a steel sheet cooling facility according to an embodiment of the present invention is shown in a side view in FIG. 1 and a plan view in FIG.

  That is, the cooling facility according to this embodiment is a passage-type cooling facility installed on a hot rolling line for steel plates, and a pair of upper headers 21 for supplying cooling water toward the upper surface of the steel plate 10 ( The first upper header 21a and the second upper header 21b) and two lower headers 31 for supplying cooling water toward the lower surface of the steel plate 10 are provided. In FIG. 1, reference numeral 13 denotes a table roller.

  A plurality of rows of circular tube nozzles 22 (first upper nozzle 22a and second upper nozzle 22b) are attached to the upper headers 21a and 21b, respectively, and an injection angle (deflection angle) θ from the first upper nozzle 22a. The supplied rod-shaped cooling water 23a and the rod-shaped cooling water 23b supplied from the second upper nozzle 22b at an injection angle (deflection angle) θ are made to face each other at a predetermined interval on the steel plate in the steel plate conveyance direction. At the same time, the rod-shaped cooling water 23 (23a, 23b) has a predetermined injection angle (outward angle) α toward both outer sides in the steel plate width direction so as to have a velocity component toward the outer side in the steel plate width direction.

  And each nozzle 22 is installed so that the outward angle | corner (alpha) may be made constant and the position (collision point) where the rod-shaped cooling water 23 collides with the steel plate 10 may become equal intervals in the steel plate width direction. At that time, in the vicinity of the center in the width direction of the steel sheet, a nozzle that inclines to the left and right in the width direction must be installed, so that the hole for attaching the nozzle can be machined to the left end of the width direction of the steel sheet. Inclined nozzle row (for example, a nozzle row having a jet velocity component in the upper direction in the upper headers 21a and 21b in FIG. 2) and a nozzle row to be tilted and ejected to the outer right end in the steel plate width direction (for example, in FIG. 2) In the upper headers 21a and 21b, nozzle rows having a jet velocity component in the downward direction are alternately shifted by a predetermined interval in the steel plate conveyance direction. Here, in the vicinity of the central portion in the width direction of the steel sheet, the injection line of the cooling water from the nozzle that inclines and injects the left end in the width direction of the steel sheet intersects the injection line of the cooling water from the nozzle that inclines and injects the right end of the steel sheet in the width direction. is doing. Moreover, the direction (arrow Z) from which the supplied cooling water 23 flows out to the steel plate width end differs from the center in the steel plate width direction.

  On the other hand, with respect to the lower header 31, here, two lower headers 31 are arranged, and a circular pipe nozzle group (lower nozzle group) 32 is attached to each of them, and a rod-shaped cooling water 33 is inserted from the gap between the table rollers 13. The cooling water is supplied to the entire width of the passing steel plate 10. In that case, each lower nozzle 32 is installed so that the position (collision point) where each rod-shaped cooling water 33 collides with the steel plate 10 may become equal intervals in the steel plate width direction.

  Incidentally, the rod-shaped cooling water of the present invention refers to cooling water that is injected from a circular (including elliptical or polygonal) nozzle outlet. In addition, the rod-shaped cooling water of the present invention is not a spray-like jet or a film-like laminar flow, but the cross section of the water flow from the nozzle outlet to the steel plate is maintained in a substantially circular shape, and is continuous and straight. Refers to water cooling water.

  And as mentioned above, even if the interval of the collision point A with respect to the steady portion of the steel plate 10 is equal to the interval W, the interval of the collision point B is the center in the steel plate width direction with respect to the warp generation portion of the steel plate 10. W2ΔW becomes narrow near the portion, and the amount of cooling water supplied to the upper surface of the steel sheet becomes non-uniform in the width direction of the steel sheet.

  Therefore, in this embodiment, as shown in the front view of FIG. 7, the lower nozzle 32 is also inclined to the outside in the steel plate width direction, like the upper nozzle 22. Here, the angle formed by the injection line viewed from a plane perpendicular to the transport direction is defined as φ, and the upper nozzle 22 side is φ1 and the lower nozzle 32 side is φ2.

  For example, when φ1 = φ2, as shown in FIG. 7, in the steady portion of the steel plate 10 (plate thickness h1), the collision points are equally spaced at W on the upper and lower surfaces of the steel plate, and the cooling water supply amount 8 is uniform in the width direction of the steel sheet, as shown in FIG. 8, when the warpage of the steel sheet 10 occurs, the upper surface of the steel sheet has a narrow collision point interval of W-2ΔW at the central portion in the width direction of the steel sheet. On the contrary, the lower surface of the steel plate has a collision point interval of W + 2ΔW that is wide as W + 2ΔW and the cooling water supply amount is reduced. 10 can be uniformly cooled in the width direction.

Incidentally, the amount of movement ΔW of the collision point in the steel plate width direction is ΔH, where the amount of change in the height position of the steel plate is ΔH.
ΔW = ΔH tanφ
It is represented by

  Here, as shown in FIGS. 7 and 8, all of the upper nozzle 22 and the lower nozzle 32 are inclined outward in the steel plate width direction, but the present invention is not limited to this, and the upper nozzle 22 and In the lower nozzle 32, it is only necessary that a part of the nozzles arranged in a large number includes a nozzle that ejects outward. For example, the injection direction at the center in the steel plate width direction is the vertical direction (φ = 0) for both the upper nozzle 22 and the lower nozzle 32, and the injection angle φ is gradually increased toward the end in the steel plate width direction. May be.

  The outward injection angle φ is set to be tan φ = 0 to 0.35 (preferably tan φ = 0.1 to 0.35).

  Incidentally, in this embodiment, the case where the rod-shaped cooling water is jetted outward is shown, but the present invention is not limited to this, for example, when the spray-like cooling water such as a spray nozzle is jetted outward. It may be used. In that case, the axis of the pipe into which the nozzle is fitted may be considered as the injection direction.

  In addition, here, the case of cooling the thick steel plate has been described in mind, but the present invention is not limited to this. For example, it may be used for run-out cooling of a thin steel plate (hot rolled steel strip), even if the tip of the steel plate floats in the air, or a loop is partially formed due to the effect of tension applied at the start of winding. It can be cooled uniformly in the width direction of the steel plate. It is also extremely effective when uniform cooling is to be performed in a process that intentionally changes the height position of the steel plate being conveyed.

  Furthermore, it is better if the upper header 21 can be moved up and down. When the plate thickness of the steel plate changes greatly, the distance between the cooling water collision points with respect to the upper surface of the steel plate becomes non-uniform at the central portion in the width direction of the steel plate as well as shown in FIGS. Therefore, if the upper header 21 is moved up and down so that the spray distance of the cooling water 23 is always constant, the cooling water collision points on the upper surface of the steady portion can be arranged at equal intervals. In addition, when cooling is not performed, the upper header 21 can be raised and retracted, so that the risk of a damage of the upper header 21 due to a collision with a steel plate having a large warpage can be reduced. And the effect on equipment maintenance, such as being able to prevent the thermal deformation of the upper header 21 by the radiant heat from a steel plate, is also large.

  Examples of the present invention are described below.

  Here, cooling was performed on a steel sheet having a thickness of 20 mm using a cooling facility having the basic configuration shown in FIGS. 1 and 2.

  At that time, the jet angle θ of the upper nozzle 22 is 45 °, the jet height (height from the upper end of the table roller to the tip of the upper nozzle) H is 1020 mm, The cooling water collision points on the upper surface were equally spaced with a 60 mm pitch in the steel plate width direction.

  As Example 1 of the present invention, based on the above-described embodiment of the present invention, the injection angle φ1 of the upper nozzle 22 and the injection angle φ2 of the lower nozzle 31 shown in FIG. 7 are all the same, and tan φ1 = tan φ2 = 0. .2 was cooled.

  Further, as Invention Example 2, based on the above-described embodiment of the present invention, the injection angle φ1 of the upper nozzle 22 and the injection angle φ2 of the lower nozzle 31 shown in FIG. 7 are all the same, and tan φ1 = tan φ2 = 0. .3 was cooled.

  On the other hand, as Comparative Example 1, as shown in FIG. 9, cooling was performed with the injection direction of the upper nozzle 22 and the injection direction of the lower nozzle 31 all set in the vertical direction (that is, φ1 = φ2 = 0).

  Further, as Comparative Example 2, as shown in FIG. 10, cooling is performed with all the injection angles φ1 of the upper nozzles 22 set to tan φ1 = 0.2 and all the injection directions of the lower nozzles 31 set to the vertical direction (that is, φ2 = 0). went.

  The cooling water amount and the cooling time were adjusted so that the cooling start temperature was 800 ° C. and the cooling end temperature was the target 600 ° C. Further, the upper curvature amount ΔH of the steel plate was 200 mm at the maximum.

  The results are shown in Table 1 and FIG.

  First, in Comparative Example 1, since the upper nozzle 22 and the lower nozzle 31 were not inclined outward in the steel plate width direction, the cooling water supply amount was uniform in the steel plate width direction on both the upper and lower surfaces of the steel plate. However, the water level of the staying cooling water 24 becomes too high, and the staying cooling water 24 may leak to the outside of the opposing rod-like cooling water 23, which partially cools the steel sheet and causes uneven temperature in the steady part. It was 60 ° C. Furthermore, in the warp generating portion, as shown in FIG. 3, a large amount of the accumulated cooling water 24 leaked to the lower height position (left side in FIG. 3), and the temperature unevenness became 100 ° C. As a result, the temperature in the steel sheet could not be made uniform, and there were many portions where the target material could not be obtained, and the yield was greatly reduced.

  Moreover, in the comparative example 2, since the upper nozzle 22 is inclined outward in the steel plate width direction, the cooling water on the steel plate upper surface easily flows out to the outer side in the steel plate width direction, and the water level of the staying cooling water 24 is not so high. The staying cooling water 24 did not leak to the outside of the opposing rod-shaped cooling water 23. Therefore, the temperature unevenness of the stationary part was 10 ° C. However, in the warp generation portion, the cooling water supply amount to the central portion in the steel plate width direction is increased on the upper surface, whereas the lower nozzle 32 is directed in the vertical direction. Therefore, the total amount of the cooling water supplied from the upper surface and the lower surface increased at the central portion in the width direction of the steel sheet. Therefore, the temperature distribution in the steel plate width direction in the warp generation portion is as shown in FIG. 11A, and the width of 2ΔW in the central portion in the steel plate width direction is overcooled, and temperature unevenness of 80 ° C. is generated. As a result, in the warp generation portion, the steel plate width direction temperature could not be made uniform, and the target material could not be obtained at the central portion in the steel plate width direction. Therefore, although improved over Comparative Example 1, the yield was considerably low.

  On the other hand, in Example 1 of the present invention, the cooling water on the upper surface of the steel sheet easily flows out to the outer side in the width direction of the steel plate, and the temperature unevenness of the steady portion was 10 ° C. . On the other hand, as for the warp generation portion, the amount of cooling water supplied to the upper surface of the central portion in the steel plate width direction was twice that of the steady portion, whereas no cooling water was supplied to the lower surface of the central portion in the steel plate width direction. Thereby, in the central part in the steel sheet width direction, excessive cooling on the upper surface and insufficient cooling on the lower surface are offset, so the temperature distribution in the steel sheet width direction in the warp generation part is as shown in FIG. The temperature unevenness could be suppressed to 15 ° C. As a result, the temperature in the steel plate could be made uniform, the target material was obtained, and a high yield could be maintained.

  Further, Example 2 of the present invention was the same as Example 1 of the present invention, and the temperature unevenness of the steady part was 10 ° C., and the temperature unevenness of the warp generation part was 15 ° C. As a result, the temperature in the steel plate could be made uniform, the target material was obtained, and a high yield could be maintained.

  From the above, the effectiveness of the present invention could be confirmed.

It is a side view which shows the structure of the cooling equipment in one Embodiment of this invention. It is a top view which shows the structure of the cooling equipment in one Embodiment of this invention. It is a figure which shows the condition when the upper curvature generate | occur | produces in the steel plate. It is a side view showing the collision point of the cooling water in a stationary part. It is a side view showing the collision point of the cooling water in a curvature generation | occurrence | production part. It is a top view showing the collision point of cooling water. It is a front view which shows the cooling state of the stationary part in one Embodiment of this invention. It is a front view which shows the cooling state of the curvature generation | occurrence | production part in one Embodiment of this invention. 6 is a front view showing a cooling state in Comparative Example 1. FIG. 10 is a front view showing a cooling state in Comparative Example 2. FIG. It is a figure which shows the steel plate width direction temperature distribution in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Steel plate 13 Table roller 21 Upper header 21a 1st upper header 21b 2nd upper header 22 Upper nozzle 22a 1st upper nozzle 22b 2nd upper nozzle 23 Rod-shaped cooling water 23a Rod-shaped cooling water 23b Rod-shaped cooling water 24 Retention cooling water 25 Leakage water 31 Lower header 32 Lower nozzle 33 Rod cooling water

Claims (6)

A cooling facility used in a hot rolling line for steel sheets,
The injection direction of at least some of the nozzles that supply cooling water to the upper surface of the steel plate and the injection direction of at least some of the nozzles that supply cooling water to the lower surface of the steel plate are respectively perpendicular to the vertical line. The steel sheet cooling equipment is characterized in that the steel sheet is inclined outward in the width direction of the steel sheet, and an area on the upper surface of the steel sheet intersects with a jet line of the cooling water projected onto a plane perpendicular to the conveying direction.   A straight line and a vertical line obtained by projecting an injection line of the cooling water on a plane perpendicular to the transport direction for each nozzle of the nozzle that supplies the cooling water to the upper surface of the steel plate and the nozzle that supplies the cooling water to the lower surface of the steel plate The steel sheet cooling equipment according to claim 1, wherein an angle formed by Φ is tan φ = 0 to 0.35 (preferably tan φ = 0.1 to 0.35).   The steel sheet cooling equipment according to claim 1 or 2, wherein the cooling water is a rod-shaped cooling water. A cooling method used in a hot rolling line for steel sheets,
The injection direction of at least some of the nozzles that supply cooling water to the upper surface of the steel plate and the injection direction of at least some of the nozzles that supply cooling water to the lower surface of the steel plate A method for cooling a steel sheet, wherein the steel sheet is tilted outward in the width direction of the steel sheet, and a region on the upper surface of the steel sheet where a jet of cooling water projected onto a plane perpendicular to the conveying direction intersects is formed.   For each nozzle of the nozzle that supplies the cooling water to the upper surface of the steel plate and the nozzle that supplies the cooling water to the lower surface of the steel plate, the angle formed by the straight line projected on the plane perpendicular to the conveying direction and the vertical line The cooling method for a steel sheet according to claim 4, wherein φ is tan φ = 0 to 0.35 (preferably tan φ = 0.1 to 0.35).   The method for cooling a steel sheet according to claim 4 or 5, wherein the cooling water is a rod-shaped cooling water.

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