JP2011212724A - Steel plate cooling equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel plate cooling equipment, which intercepts cooling water from overflowing over draining rollers into adjacent cooling zones.SOLUTION: The steel plate cooling equipment includes: a header, which is set above a hot-rolling line for a steel plate and supplies cooling water to the upper surface of the steel plate; cooling water spray nozzles, which are attached to the header; and draining rollers, which are arranged front and behind the header. Further, the steel plate cooling equipment has a water intercepting device provided with a cover, which covers the upper part of the draining roller along the outer circumferential face of the roller in a non-contact manner, and with a vertical plate extending upward from the cover.

Description

  The present invention relates to a steel sheet cooling facility for cooling a hot-rolled steel sheet.

  In the process of manufacturing a steel plate by hot rolling, for example, in an equipment as shown in FIG. 7, after hot rough rolling and finish rolling, the structure is controlled by water cooling or air cooling. When cooling to a relatively low temperature, for example, about 450 to 650 ° C. by water cooling, fine ferrite and bainite structure can be obtained and the strength of the steel sheet can be secured. Therefore, there is a technology for cooling the steel sheet with spray cooling water, laminar cooling water, etc. It is common. In recent years, the development of techniques for increasing the strength of steel sheets by obtaining a high cooling rate and making the structure finer is increasing.

  For example, there is a technique of Patent Document 1 as a technique for rapidly cooling a steel sheet by supplying a large amount of cooling water. This is because many cooling banks are installed on the upper and lower surfaces of the hot-rolled steel strip, each cooling bank is separated by a draining roll, and the number of cooling water discharge banks is increased or decreased depending on the transport speed and finishing temperature of the steel strip. It is said that even at a very high cooling rate, it is possible to produce a product having excellent material properties that are homogeneous in the longitudinal direction of the steel strip.

JP 2003-145214 A

  However, in order to rapidly cool the steel sheet, the conventional technique has a problem in ensuring the cooling capacity and the cooling uniformity.

  The technique of Patent Document 1 supplies a large amount of cooling water in order to obtain a high cooling rate, and the cooling water film staying on the upper surface of the steel sheet becomes thicker as the amount of cooling water is increased. When a large amount of cooling water is supplied, the accumulated water may get over the draining roll and overflow into the adjacent cooling zone. If the stagnant water overflows into the non-water cooling zone, the steel plate is overcooled, and temperature unevenness occurs on the upper and lower surfaces of the steel plate, making it impossible to produce a steel plate with uniform quality. In particular, in the case of a thick steel plate, since the plate width is wide and the cooling water supplied near the center of the plate width is difficult to drain from the end portion of the plate width, the water level of the water film tends to be high. Therefore, it was necessary to suppress the amount of cooling water to such an extent that stagnant water does not overflow from the draining roll.

  In view of the above, the present invention provides cooling water that overflows to the adjacent cooling zone beyond the draining roll even when supplying a large amount of cooling water to the upper surface of the steel sheet when supplying cooling water to the upper surface of the steel sheet. It aims at providing the steel plate cooling equipment which provided the water-blocking apparatus which can be interrupted | blocked.

As a water-impervious device, for example, it is conceivable that the water-impervious plate is brought into contact with the upper part of the draining roll, but when such a water-impervious plate is brought into contact with the rotating drainer roll,
(1) Since the portion where the water shielding plate comes into contact with the draining roll wears out, the water shielding performance deteriorates and it is necessary to replace it with a new one as the wear progresses. There is a problem that causes

  Therefore, the present inventor studied to solve this problem, and by using a cover that covers the vertical plate and the draining roll as the water shielding plate, water shielding is possible even in a structure where the water shielding plate does not contact the draining roll. It was discovered that the present invention was made. The summary is as follows.

  1st invention is installed in the hot rolling line of a steel plate, the header which supplies cooling water to the upper surface of a steel plate, the cooling water injection nozzle attached to this header, and the draining roll arrange | positioned before and behind the said header A water-cooling device provided with a cover that covers the upper part of the draining roll in a non-contact manner along its outer peripheral surface, and a vertical plate extending upward from the cover. This is a steel sheet cooling facility.

  The second invention is the steel sheet cooling facility according to the first invention, wherein the water shielding device is further provided with an air purge header for supplying compressed air to a gap between the cover and the draining roll. .

  Since the water-impervious device of the present invention does not come into contact with the rotating draining roll, there is no deterioration in the water-impervious performance due to wear of the cover, and the cooling water overflow to the adjacent cooling zone can be suppressed. In particular, when an air purge header is installed, extremely high water shielding performance can be exhibited even when the conveying speed is high, such as hot rolling of a hot-rolled steel strip.

  Further, according to the present invention, the influence of disturbance due to the overflow of the cooling water is eliminated in each zone of the steel sheet cooling facility, and the cooling water sprayed from the nozzle in each zone contributes almost completely to the cooling of the steel sheets. The variation in cooling characteristics is reduced, and a uniform temperature distribution can be obtained in the longitudinal direction of the steel sheet.

It is a side view of the steel plate cooling equipment concerning a 1st embodiment. It is a figure which shows the external appearance of the water shielding apparatus in 1st Embodiment. It is a side view of the steel plate cooling equipment which concerns on 2nd Embodiment. It is a figure which shows the internal appearance of the water shielding apparatus which concerns on 2nd Embodiment. It is a figure which shows the example of installation of the compressed air ejection opening which concerns on 2nd Embodiment. It is a side view of the steel plate cooling equipment which shows the other example which concerns on 2nd Embodiment. It is the schematic which shows an example of a steel plate manufacturing process.

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

FIG. 7 is a schematic view showing an example of a steel sheet rolling line used for carrying out the present invention.
The slab extracted from the heating furnace is subjected to rough rolling and finish rolling by a rolling mill to a predetermined finishing temperature and finishing plate thickness, and then conveyed to an accelerated cooling facility online. In the accelerated cooling facility, the steel sheet is cooled to a predetermined temperature by the cooling water sprayed from the upper surface cooling facility and the lower surface cooling facility. In order to obtain a uniform material, it is preferable to perform accelerated cooling after adjusting the shape of the steel sheet through a pre-leveler before cooling.

(First embodiment)
FIG. 1 is a side view showing the arrangement of steel plate cooling equipment according to the first embodiment of the present invention. Here, the case where the present invention is used for cooling a steel plate in a thick plate rolling process will be described as an example.
In the upper surface cooling equipment, an upper header 6 for supplying cooling water to the upper surface of the steel plate 3, an upper cooling water injection nozzle 8 suspended from the upper header 6, and a draining roll 4 are installed before and after the upper header 6. Yes.

  The draining roll 4 is installed at a position facing the transport roll 5 with the steel plate 3 sandwiched before and after the upper header 6 so that the cooling water supplied to the upper surface of the steel plate 3 does not spread in the longitudinal direction of the steel plate 3. Thus, the length of the cooling zone by the upper header 6 becomes constant, and the cooling temperature control becomes easy. Moreover, the flow of the cooling water in the conveyance direction of the steel sheet is blocked by the draining roll 4, and the accumulated water 13 of the cooling water supplied from the upper header 6 flows to the outside in the width direction of the steel sheet.

  Above each draining roll 4, a water shielding device comprising a cover 2 that covers the upper part of the draining roll 4 in a non-contact manner in the roll axial direction and a vertical plate 1 extending upward from the cover 2 is provided. The roll 4 is attached to a cooling device main body (not shown) with a predetermined distance from the outer peripheral surface. By making non-contact with the rotating draining roll 4, the cover 2 is not worn and the water shielding performance is not deteriorated.

  FIG. 2 is a view showing the external appearance of the water shielding device. The cover 2 has an arc shape along the outer periphery of the draining roll 4, and the vertical plate 1 is attached to the apex of the arc. Both the cover 2 and the vertical plate 1 are installed over the entire length of the draining roll 4 in the axial direction. Note that the arc shape of the cover 2 is preferably a semicircular shape that covers the upper half of the draining roll 4, but the function can be sufficiently exerted if it is about ¼ or more of the circumference.

  According to such a water shielding apparatus for cooling equipment according to the first embodiment, the water level of the retained water 13 on the upper surface of the steel plate 3 exceeds the height of the draining roll 4 or is injected from the upper cooling water injection nozzle 8. Even if the cooled water collides with the surface of the stagnant water 13 and splashes over the draining roll 4, the leakage of the cooling water to the adjacent cooling zone is blocked by the vertical plate 1 of the water shielding device. Can do.

  In addition, since the draining roll 4 and the cover 2 are not in contact with each other, there is a concern that the accumulated water 13 on the upper surface of the steel plate leaks from this gap to the adjacent cooling zone. In particular, in the case where the downstream side of the cooling zone in the steel plate conveyance direction is an air cooling zone, if the stagnant water leaks into the air cooling zone, the leaked cooling water spreads downstream on the steel plate 3, so that the influence is great. However, since there is an accompanying flow (an accompanying flow 14 in FIG. 3 described later) from the downstream side in the steel plate transport direction of the draining roll 4 along with the rotation of the draining roll 4 in this gap, the accumulated water is this It does not leak to the downstream side through the gap.

  Further, since the hot rolling of thick steel plates generally has a lower conveying speed than the rolling of hot-rolled steel strips, the stagnant water 13 on the upper surface of the steel plate becomes an accompanying flow along with the rotation of the draining roll 4. The amount of overflow to the cooling zone upstream in the transport direction is limited and does not cause a problem. Further, since the cover 2 is not in contact with the draining reroll 4, the cover 2 is not worn and the accumulated water 13 does not flow out.

(Second Embodiment)
FIG. 3 is a side view of a steel plate cooling facility according to the second embodiment of the present invention. Here, a case where the present invention is used for cooling a steel strip in a hot rolling process of a hot-rolled steel strip will be described as an example.

Of the cooling facilities described below, the facilities other than the air purge header 9 are the same as those in the first embodiment, and therefore, the same parts are denoted by the same reference numerals and detailed description thereof is omitted.
In the upper surface cooling equipment, an upper header 6 for supplying cooling water to the upper surface of the steel plate 3, an upper cooling water injection nozzle 8 suspended from the upper header 6, and a draining roll 4 are installed before and after the upper header 6. Yes.

  Above each draining roll 4, there is a cover 2 that covers the upper part of the draining roll 4 in a non-contact manner along the roll axis direction, a vertical plate 1 extending upward from the cover 2, the cover 2, and the draining roll. A water shielding device including an air purge header 9 that supplies compressed air to a gap with the water 4 is attached to a cooling device main body (not shown) with a predetermined distance from the outer peripheral surface of the draining roll 4.

  4A is an external view of the water shielding device, and the shape of the cover 2 has an arc shape along the outer periphery of the draining roll 4, and the air purge header 9 is at the apex of the arc and the air purge header 9 is at the apex. A vertical plate 1 is attached. The cover 2, the air purge header 9, and the vertical plate 1 are all installed over the entire length of the draining roll 4 in the axial direction. Note that the arc shape of the cover 2 is preferably a semicircular shape that covers the upper half of the draining roll 4, but the function can be sufficiently exerted if it is about ¼ or more of the circumference.

  FIG. 4B is a diagram in which the inner surface side of the cover 2 is developed in the axial direction of the draining roll 4, and the air purge header 9 is provided with a number of injection ports 10 for injecting compressed air in the axial direction of the draining roll 4. Yes. FIG. 4 shows an example in which the compressed air injection port 10 is directed in the axial direction of the draining roll 4.

  FIG. 5A is a side view of the air purge header 9, and a section taken along the line aa is shown in FIGS. 5B and 5C. FIG. 5B shows the case where the compressed air injection port 10 has one hole, but the compressed air injection port 10 is inclined in the direction of the accompanying flow 14 so that the compressed air is more opposed to the accompanying flow 14. Is shown. FIG. 5C shows a case where the compressed air injection ports 10 are inclined as two holes so that the compressed air runs along both sides of the outer surface of the draining roll 4.

  According to the water shielding apparatus for cooling equipment according to the second embodiment, the water level of the accumulated water 13 on the upper surface of the steel plate 3 exceeds the height of the draining roll 4 or is injected from the upper cooling water injection nozzle 8. Even if the cooled water collides with the surface of the stagnant water 13 and splashes over the draining roll 4, the leakage of the cooling water to the adjacent cooling zone is blocked by the vertical plate 1 of the water shielding device. Can do.

  In addition, since the hot rolling of the hot-rolled steel strip shown in FIG. 3 has a significantly higher steel plate conveyance speed than the rolling of thick steel plates, the depth of the cooling water staying on the upper surface of the hot-rolled steel strip is reduced by draining. Even if it is shallower than the height of the roll 4, as the draining roll 4 rotates, it becomes an accompanying flow 14 between the draining roll 4 and the cover 2 to the cooling zone on the upstream side in the transport direction of the hot-rolled steel strip. It may overflow. On the other hand, in the water shielding device of the cooling device according to the second embodiment, this gap is obtained by injecting the compressed air 11 from the compressed air injection port 10 of the air purge header 9 into the gap between the draining roll 4 and the cover 2. A layer of air can be formed on the surface and the stagnant water 13 can be prevented from flowing out to the adjacent cooling zone through this gap.

  In particular, as described with reference to FIG. 5B, the compressed air injection port 10 is directed in the steel strip conveying direction, and the compressed air 11 is injected in a direction (steel strip conveying direction) opposite to the rotation direction of the draining roll 4. Thus, the flow can be stopped against the accompanying flow 14 accompanying the rotation of the draining roll 4, and the flow into the adjacent cooling zone can be further prevented. In addition, although the injection direction of the compressed air 11 is preferably on the side facing the accompanying flow (on the downstream side in the transport direction), it is preferably on both sides as shown in FIG.

  FIG. 6 shows a case where the stagnant water 13 is higher than the height of the draining roll 4 when supplying a large amount of cooling water. In this case, a large amount of compressed air 11 is jetted on both sides of the draining roll 4 and the overflow of the accumulated water 13 can be prevented by the vertical plate 1 and the cover 2.

  In addition, it is preferable that the space | interval of the cover 2 which covers the draining roll 4 and the draining roll 4 shall be about 10-15 mm. If the interval is less than 10 mm, there is a risk that the cover 2 may come into contact with the rotating draining roll 4. If the interval exceeds 15 mm, the stagnant water 13 is blocked between the draining roll 4 and the cover 2 in the first embodiment. This is because it is difficult to keep water, and in the second embodiment, it is necessary to set the pressure and flow rate of the compressed air 11 to high pressure and high flow rate, which is not efficient.

  The flow rate and injection speed of the compressed air 11 may be appropriately set in consideration of the distance between the draining roll 4 and the cover 2, the amount of staying water 13, the conveying speed of the steel plate, and the like. For example, when the air purge header 9 has a length of 5 m, the compressed air injection ports 10 are arranged in two rows (FIG. 5C), the lengthwise pitch is 30 mm, and the compressed air injection port 10 has an inner diameter of 8 mm, the injection of the compressed air 11 is performed. In order to obtain a speed of 10 m / s, the flow rate per injection port is about 0.5 L / s, so the flow rate per air purge header is about 166 L / s. In addition, cooling of a hot-rolled steel strip using the steel plate cooling equipment which concerns on the 2nd Embodiment of this invention which used the flow volume and injection speed of the above compressed air 11, and set the space | interval of the draining roll 4 and the cover 2 to 10 mm. As a result, it was confirmed that the leakage of cooling water to the adjacent cooling zone could be almost completely blocked.

  In the second embodiment, the hot-rolled steel strip is taken as an example, but it is not denied that the air purge header 9 is installed in cooling the thick steel plate. Even in the cooling of the thick steel plate, if the amount of cooling water is large and the retention of the cooling water is large, an accompanying flow along the draining roll 4 may occur, and the staying cooling water exceeds the height of the draining roll 4 It is also possible.

DESCRIPTION OF SYMBOLS 1 Vertical plate 2 Cover 3 Steel plate / steel strip 4 Draining roll 5 Conveyance roll 6 Upper header 7 Lower header 8 Upper injection nozzle 9 Air purge header 10 Compressed air injection port 11 Compressed air 12 Lower injection nozzle 13 Stagnant water 14 Accompanying flow 15 Pressure reducing valve 16 Air source

Claims (2)

  Steel sheet cooling provided with a header for supplying cooling water to the upper surface of the steel sheet, a cooling water injection nozzle attached to the header, and a draining roll disposed before and after the header, installed in a hot rolling line for the steel sheet A steel plate cooling facility comprising a water shielding device provided with a cover that covers the upper part of the draining roll in a non-contact manner along an outer peripheral surface thereof, and a vertical plate extending upward from the cover. .   The steel sheet cooling equipment according to claim 1, wherein an air purge header that supplies compressed air to a gap between the cover and the draining roll is further provided in the water shielding device.

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