JP5685861B2 - Draining device, draining method and cooling equipment for hot steel plate - Google Patents

Description

The present invention relates to a water draining device , a water draining method, and a cooling facility for a hot steel plate cooled by cooling water in a cooling line.

  Examples of high-temperature steel plates (hereinafter referred to as “hot steel plates”) include hot-rolled steel strips and thick plates after hot rolling. These hot steel plates are cooled by a cooling device in a cooling line after hot rolling. Water (cooling medium) is sprayed onto the hot steel sheet to cool it. For example, the production line of the hot-rolled steel strip is shown in FIG. 3, but the slab taken out from the heating furnace 7 is roughly rolled by the roughing mill 8 and then finish-rolled by the finishing mill 9. The slab is formed into a steel strip (hot steel plate) 1. Next, cooling water is sprayed onto the hot steel plate by the cooling device 2a for cooling or further air cooling to control the structure of the steel strip.

  When cooling with cooling water is performed, on the upper surface of the hot hot steel sheet after hot rolling, the cooling water flows out to the upstream side of the cooling device and to the downstream side of the cooling device and stays on the upper surface of the hot steel sheet, so-called stagnant water. Occur. If this stagnant water is not immediately removed, supercooling occurs at the portion of the hot steel sheet where the stagnant water stays, resulting in a temperature difference in the surface of the hot steel sheet. When this temperature difference is large, mechanical properties vary or shape defects occur in the cooled steel sheet, and the quality deteriorates. For this reason, it is important to remove the stagnant water on the upper surface of the hot steel sheet promptly.

  As a technology to remove the accumulated water on the upper surface of the hot steel sheet, the cooling water (retained water) staying on the upper surface of the hot steel sheet is finally discharged from the spray nozzle to drain water to one side edge of the hot steel sheet, A draining device and draining method for removing stagnant water on the upper surface of a steel plate are known (Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 11-123439 JP 2001-353515 A

As shown in FIG. 4, the technique described in Patent Document 1 is such that cooling water jetted from the cooling header 2 b of the cooling device flows out and remains at the downstream side of the cooling device or the upstream side of the cooling device. However, the draining water (high-pressure water) 5 from the spray nozzle of the draining device 4 is directed to the upper surface of the hot steel plate 1 in the direction opposite to the cooling water outflow direction (that is, upstream on the outlet side, downstream on the inlet side). ), And drains the cooling water that has become defective in drainage by pushing high-pressure water from the two nozzles of the outer side spray 11 to the side edge of the hot steel plate to remove the cooling water. It is to do.
However, it is not completely removed by the side spray 11, and a part of the cooling water remains on the upper surface of the hot steel sheet, particularly in the vicinity of both side edges as stagnant water, resulting in uneven temperature distribution and supercooling to the hot steel sheet. Will occur. Moreover, supercooling also occurs when water sprayed from the side spray bounces off at the side guides of the cooling line and again rides near the side edges of the hot steel plate. As described above, this supercooling causes a decrease in quality, which is a problem.

  Further, as shown in FIG. 5, the technique described in Patent Document 2 has a hot steel plate upper surface on the downstream side on the outlet side and the upstream side on the inlet side after the cooling water 3 b is ejected from the cooling header 2 b. The cooling water (residual water) 3a remaining on the hot steel plate is sprayed over the entire width of the hot steel plate toward the one side edge portion by spraying a draining fluid (water or air) 5 toward the one side edge portion of the hot steel plate. It is removed by rushing away. Also in this case, if the cooling water 3a staying on the upper surface of the hot steel plate cannot be removed by the draining device 4, the draining water is sprayed in the direction of one side edge, so that the cooling water is side edge as shown in FIG. The temperature distribution in the width direction becomes uneven and the temperature distribution in the width direction becomes non-uniform, and supercooling occurs before the cooling water flows down. As a result, a temperature difference occurs in the surface of the hot steel sheet, and the quality deteriorates as described above. Was a problem.

  Conventionally, there has been no specific index for spraying drain water for removing cooling water remaining on the upper surface of the hot steel sheet. When spraying water more than necessary to completely drain water, the hot steel sheet is supercooled by the water draining water itself, resulting in deterioration of quality. In addition, there is a problem that the installation cost of the drainer becomes enormous.

In view of the above, in the cooling line in which the hot steel plate is conveyed, the present invention is such that the cooling water supplied to the hot steel plate is on the upper surface of the hot steel plate on the upstream side of the cooling device on the inlet side and on the downstream side of the outlet side of the cooling device. An object of the present invention is to provide a water draining device , a water draining method, and a cooling facility equipped with the water draining device on the upper surface of the hot steel plate, which can prevent the outflow and uniformly reduce the variation in the cooling material and deformation of the steel plate. .

Therefore, in the present invention, the inventors of the present invention arrange the draining device upstream and downstream of the cooling device, and direct the draining water sprayed from the nozzle of the draining device toward the side edge of the hot steel plate. Rather than spraying, it is a direction orthogonal to the width direction of the hot steel sheet conveyed in the cooling zone of the cooling device (the traveling direction of the cooling line, that is, the conveying direction of the hot steel sheet), and provided on the inlet side of the cooling device The draining water of the draining device is sprayed over the entire width of the upper surface of the hot steel sheet toward the downstream side of the inlet side, and the draining water of the draining device provided on the outlet side of the cooling device is directed upstream of the outlet side.
Furthermore, the present inventors examined the condition of draining water that can quickly remove the cooling water staying on the hot steel plate after cooling. As a result, the unit time and the momentum per unit width of the draining water from the draining device may be within a predetermined range with respect to the unit time and unit moment in the line traveling direction of the accumulated water after cooling. The knowledge that it was necessary was obtained, and based on this, the momentum of the draining water was adjusted to a predetermined range, and the present invention was completed.

In order to solve the above problems, the present invention employs the following means.
[1] A draining device for the upper surface of a hot steel plate disposed on the upstream side and the downstream side on the outlet side of the cooling device, the draining device including a header provided with a nozzle for spraying drain water on the upper surface of the hot steel plate, and the header The unit has cooling water in the gap between the draining roll and the thermal steel sheet, and the momentum per unit width of the draining water and the momentum per unit width. Maintaining the momentum within a range of 1.5 to 5 times the momentum per unit width, spraying draining water from the nozzle in the direction orthogonal to the width direction of the hot steel plate and over the entire width of the hot steel plate, and cooling device Draining of the upper surface of the hot steel sheet disposed on the upstream side and the downstream side of the cooling device, wherein the cooling water can be prevented from flowing out to the upstream side of the inlet side and the downstream side of the outlet side apparatus.
[2] The spraying direction of draining water sprayed from draining devices provided upstream and downstream of the cooling device has an angle of 30 to 70 ° with respect to the vertically downward direction . [1] A draining device for the upper surface of the hot steel plate disposed on the inlet side upstream side and the outlet side downstream side of the cooling device.
[3] The nozzle according to [1] or [2], wherein the nozzle of at least one draining device of the draining device provided upstream and downstream of the cooling device is a slit type nozzle . A draining device for the upper surface of the hot steel sheet disposed upstream and downstream of the cooling device.
[4] At least one draining device of the draining device provided on the upstream side and the downstream side of the cooling device is composed of one or more rows of headers having porous direct nozzles, and the nozzle has a hole diameter of 1 to 6 mm. And the pitch is 10 times or less of this hole diameter, The draining device of the hot steel plate upper surface arrange | positioned in the inlet side upstream and outlet side downstream of the cooling device as described in [1] or [2] .
[5] At least one draining device of the draining device provided upstream and downstream of the cooling device includes a header provided with a plurality of spray nozzles, and drains water sprayed from the nozzles (spray water) ) Is 40 to 90 °, and the width direction injection region on the upper surface of the hot steel plate overlaps with the draining water (spray water) of the adjacent nozzle by 30% or more, [1] or [2 ] The draining device of the hot-steel plate upper surface arrange | positioned at the inlet-side upstream and outlet-side downstream of the cooling device as described above .
[6] A header provided with a nozzle for injecting drained water onto the upper surface of the hot steel plate on the inlet side upstream and outlet side of the cooling device, and a drainer disposed closer to the cooling device than the header and close to the upper surface of the hot steel plate Disposing a draining device comprising a roll, the unit time of the draining water, the momentum per unit width, the unit time of the cooling water in the gap between the draining roll and the hot steel sheet, the momentum per unit width of 1.5-5 In the direction perpendicular to the width direction of the hot steel sheet and over the entire width of the hot steel sheet, spraying drain water from the nozzle to the upstream side on the inlet side and the downstream side on the outlet side of the cooling device. A method for draining the upper surface of the hot steel sheet, wherein the cooling water can be prevented from flowing out.
[7] A method for draining an upper surface of a hot steel sheet, wherein the water draining apparatus according to any one of [1] to [5] is used in a production line for a hot steel sheet having a cooling device.
[8] A thermal steel sheet cooling facility comprising a cooling device for cooling the hot steel plate and the draining device according to any one of [1] to [5] .

  In the present invention, the momentum of the draining water is adjusted to a predetermined range to prevent the cooling water from flowing out from the cooling zone of the cooling device to the upstream side and the downstream side of the cooling device to become stagnant water, and By discharging the cooling water not from one side edge of the hot steel sheet but from both side edges, supercooling is eliminated and uniform cooling can be achieved in the width direction of the steel sheet. High hot steel sheet can be manufactured.

An example of the drainer is shown. The draining device of the present invention is shown (when there is a draining roll). The hot rolling equipment is shown. The drainage apparatus of a prior art (patent document 1) and the temperature distribution of a board width direction are shown. The draining device of another prior art (patent document 2) and the temperature distribution of the board width direction are shown. The draining device of the present invention is shown (slit nozzle). The draining device of the present invention is shown (porous direct spray nozzle). The draining device of the present invention is shown (spray nozzle).

Hereinafter, based on the production line of a hot-rolled steel strip as a hot steel plate, embodiment of this invention is described.
As shown in FIG. 3, the slab carried out from the heating furnace 7 is roughly rolled by a roughing mill 8, then finish-rolled by a hot finish rolling mill 9 and rolled into a hot-rolled steel strip 1, and then a cooling device Cooling water is jetted from the cooling header 2a to cool it, and it is wound up as a coil by the winder 10.
In the cooling zone of the cooling device, usually, a number of cooling headers 2b that traverse the hot steel plate in the width direction are arranged in the conveying direction of the hot steel plate, and cooling processing can be performed by injecting cooling water onto the upper surface of the hot steel plate. ing.

A draining device is provided on the upstream side and the downstream side of the cooling device 2a, and FIG. 1 schematically shows an example of an embodiment of the draining device that removes the cooling water (residual water) remaining on the upper surface of the hot steel sheet. It shows.
FIG. 1 shows a cooling header 2b in a cooling device 2a for supplying cooling water to the upper surface of the hot steel plate and a draining device 4 for injecting drained water. When the hot steel plate is transported from the left side to the right side of the drawing, the draining device on the downstream side of the cooling device 2a is used. When the hot steel plate is transported from the right side to the left side of the drawing, the cooling device 2a is provided upstream of the inlet side. A draining device is shown respectively.

  The hot-rolled steel strip (hot steel plate) 1 after finish rolling is cooled by cooling water 3b injected from the cooling header 2b of the cooling device 2a in the cooling line. On the inlet side upstream and outlet side downstream of the cooling device 2a, a header 4 which is a draining device of the present invention is provided so as to cross the hot steel plate in the width direction, and from the header nozzle to the hot steel plate width direction. Draining water 5 is jetted toward the cooling water 3a on the upper surface of the steel strip that has flowed out to the upstream side of the cooling device and the downstream side of the cooling device across the entire width of the hot steel plate in the direction perpendicular to the line (the traveling direction of the line, the conveying direction of the hot steel plate) However, the draining water of the draining device provided upstream of the inlet side of the cooling device is directed downstream of the inlet side, and the draining water of the drainer device provided downstream of the outlet of the cooling device is upstream of the outlet side. It is injected towards.

Therefore, in this embodiment , the draining device provided on the upstream side and the downstream side on the outlet side of the cooling device prevents the cooling water from staying on the upper surface of the hot steel sheet as the retained water because it is blocked. As well as being able to flow out from the both side edges of the hot steel plate, it will flow out evenly. Since the accumulated water does not flow out from one side edge of both side edges as in the prior art described above, this draining device eliminates overcooling and provides more uniform cooling in the width direction of the hot steel sheet. It is.
Moreover, even if draining water affects the cooling of the hot steel sheet, the amount of the cooling water supplied from the cooling device to the hot steel sheet can be adjusted by obtaining the degree of the effect in advance through experiments or the like.

  The nozzle provided in the header 4 may be a single slit nozzle as shown in FIG. 6, a porous direct nozzle as shown in FIG. 7, or a plurality of spray nozzles as shown in FIG. 8. Good. In any case, it is necessary to cover the entire width of the hot steel strip with drained water. Moreover, such a header can also be installed in the width direction of a hot-steel plate, and it can also be set as the draining apparatus by 2 or more rows.

The momentum per unit time and unit width in the line traveling direction of the cooling water staying on the upper surface of the hot steel sheet on the inlet side and outlet side of the cooling device (that is, the conveying direction of the hot steel sheet) can be obtained as follows. it can.
When there is stagnant water on the upper surface of the hot steel plate, the flow velocity at the depth x from the liquid surface is (2gx) ^0.5 from Bernoulli's equation, and the momentum per unit time and unit width is 2ρgx. Here, g is the acceleration of gravity, and ρ is the density of the fluid (here, water).

  As shown in FIG. 1, since water draining is performed on the entry side and the exit side in the line traveling direction of the cooling device, the liquid level height h of the cooling water staying on the upper surface of the hot steel plate in the cooling zone by cooling is as follows. From the relationship between the amount of water input to the upper surface and the amount of water flowing down from the edge of the plate, it can be obtained by the following equation (1).

ここでＱは冷却設備の水量密度、Ｗは熱鋼板の幅、Ｌは熱鋼板の搬送方向に測定した冷却装置における冷却長である。 (Cooling water amount = Outflow water amount from the plate side edge)

Here, Q is the water density of the cooling facility, W is the width of the hot steel plate, and L is the cooling length in the cooling device measured in the conveying direction of the hot steel plate.

式（２）で示すように、ｍ_０はＱとＷによって変化する。 With respect to the liquid level height h, the momentum m ₀ per unit time and unit width that is about to flow out in the direction of the cooling water line on the upper surface of the hot steel sheet can be obtained by the following equation (2).

As shown in the equation (2), m ₀ varies depending on Q and W.

W is usually different for each product, but when W is the maximum product width W ₀ , the unit time and the momentum M ₀ per unit width to flow out in the direction of the cooling water line on the hot steel plate are as follows: It can be obtained from equation (3).

An embodiment of the present invention that can reduce the momentum of the cooling water by disposing the draining roll 6 close to the upper surface of the hot steel plate near the cooling zone outside the cooling zone of the cooling device is shown in FIG. .
That is, a header 4 and a draining roll 6 for injecting drained water 5 are arranged in the traveling direction of the line at the upstream side of the cooling device, and a draining roll 6 is disposed in the traveling direction of the line at the downstream side of the cooling device. And the header 4 are arranged, the unit time and the momentum m ₀ ′ per unit width of the cooling water staying on the upper surface of the hot steel plate on the inlet side and the outlet side of the cooling zone are about to flow out in the line traveling direction. It can obtain | require by following formula (4).

ここでｄは水切りロールと熱鋼板との隙間の距離である。

Here, d is the distance between the draining roll and the hot steel sheet.

W in formula (4) is also usually different for each product, but when W is the maximum product width W ₀ , the unit is about to flow out in the direction of the cooling water line on the hot steel plate when there is a draining roll. The momentum M ₀ ′ per unit time and unit width can be obtained from the following equation (5).

ここで、式（６）は、図６に示すような、スリットノズルの単位時間、単位幅あたりの運動量を表す式であり、Ｑ_１はノズルの単位幅あたりの水量、ａ_１はノズルギャップ、θは水切り水の噴射線と鉛直下向きとなす角度である。
・水切り装置のノズルが多孔式の直射ノズルである場合 The unit time and the momentum M _{1 to} M ₃ per unit width of the water sprayed from the nozzle of the draining device can be obtained by the following formulas (6) to (8) according to the form of the nozzle of the draining device. Can be sought.
・ When the nozzle of the drainer is a single slit type nozzle

Here, Equation (6), such as shown in FIG. 6, the unit of the slit nozzle time, an expression that represents the momentum per unit width, Q ₁ is the amount of water per unit width of the nozzle, a ₁ is the nozzle gap, θ is an angle formed between the spray line of the drained water and the vertically downward direction.
・ When the nozzle of the drainer is a perforated direct nozzle

ここで、式（７）は、図７に示すような、水切り装置のノズルが多孔式の直射ノズルの単位時間、単位幅あたりの運動量を表す式であり、ｌ（エル）はノズルピッチ、
ｎはノズル列数、Ｑ_２はノズル１列の単位幅あたりの流量、ａ_２はノズル径である。
・水切り装置のノズルが複数のスプレーノズルで構成される場合

Here, the equation (7) is an equation representing the momentum per unit width and unit width of the nozzle of the draining device as shown in FIG. 7, where l (el) is the nozzle pitch,
n is the number of nozzle rows, Q ₂ is the flow rate per unit width of one nozzle row, and a ₂ is the nozzle diameter.
・ When the nozzle of the drainer is composed of multiple spray nozzles

Here, the equation (8) is an equation representing the momentum per unit time and unit width of the spray nozzle as shown in FIG. 8, where Q ₃ is the flow rate per nozzle, p is This is the injection pressure.

When draining, M _{1 to} M ₃ corresponding to formulas (6) to (8) are 1.5 to 5 times as much as m ₀ determined by formula (2) by the spraying method of the draining device. By spraying in such a way, draining can be performed without leakage of cooling water by draining water. When it is smaller than 1.5 times, the cooling water staying on the upper surface of the hot steel sheet cannot be completely removed, and overcooling occurs, resulting in a deterioration in quality.
On the other hand, when the water density is higher than 5 times, a large amount of draining water is jetted from the draining device, and the hot steel sheet is supercooled by the draining water itself, resulting in deterioration of quality.

In the case of the present invention in which a draining roll is arranged outside the cooling device, the unit time in the outflow direction of the cooling water staying on the upper surface of the hot steel plate and the momentum per unit width are expressed by equation (4) instead of equation (2). Use it.
As already described, since W varies from product to product, the momentum of the expected maximum product width W ₀ is obtained by calculating Mo and Mo ′ using equations (3) and (5), in _contrast, 1.5-5 times the M 1 defined ~M ₃ a in the range of 1.5 to 5 times, and even for Wo smaller _W, M 1 ~M ₃ is _{m 0} and _{m 0} ' If it is within the range, it is not necessary to control M _{1 to} M ₃ for each value of the product width W.

As described above, the direction of spraying the draining water of the draining device is that the draining water of the draining device provided on the inlet side of the cooling device is provided on the outlet side of the cooling device toward the downstream side of the inlet side. The draining water of the draining device needs to be sprayed in the direction perpendicular to the width direction of the hot steel sheet (the conveying direction of the hot steel sheet) toward the upstream side of the outlet side, over the entire width of the upper surface of the hot steel sheet.
When water draining water is injected in a direction not orthogonal to the width direction of the hot steel sheet, that is, when water draining water is sprayed toward one hot steel sheet side edge, as shown in FIG. One side edge side is further cooled, a temperature difference is generated in the width direction, and quality is deteriorated.

  Moreover, as shown to FIGS. 6-8, the injection direction of the draining water of a drainer should have an angle of 30-70 degrees with respect to a perpendicular direction. Preferably 40-60 degrees is good. If it is larger than 70 °, the distance between the water draining device and the water draining position on the upper surface of the hot steel plate becomes long, which may interfere with other equipment and cannot be installed. On the other hand, if the angle is smaller than 30 °, the backflow of drained water sprayed from the draining device causes overcooling, resulting in deterioration of quality.

  When the nozzle of the draining device is a porous direct nozzle, the nozzle hole diameter is preferably 1 to 6 mm. If it is smaller than 1 mm, the nozzle is likely to be clogged, and therefore, when used for a long period of time, defective draining occurs and the quality is deteriorated. On the other hand, if it is larger than 6 mm, a large amount of water is required to secure a desired momentum, resulting in an increase in equipment cost. The nozzle pitch is preferably 10 times or less the nozzle hole diameter. If it is larger than 10 times, the stagnant water that cannot be drained flows out from between the nozzles, so that overcooling occurs and the quality deteriorates.

  When the nozzle of the draining device is a spray nozzle, the spray spread angle should be 40 to 90 °, and the spray region in the width direction should overlap 30% or more on the upper surface of the hot steel sheet. When the overlap allowance is smaller than 30%, when the hot steel sheet warps, the spray overlaps, resulting in poor draining, resulting in quality deterioration. Also, if the spray spread angle is less than 40 °, the number of nozzles increases and the desired overlap cannot be obtained. If it is larger than 90 °, the injection speed component in the width direction increases, so the momentum in the transport direction of the hot steel sheet (the direction toward the upstream side on the outlet side of the cooling device) decreases, resulting in poor draining and poor quality. Invite.

  In this invention, although the draining device is arrange | positioned at the entrance side and exit side of a cooling device, the draining device of an entrance side and an exit side does not need to be the same. For example, a slit type nozzle may be adopted as the nozzle of the draining device on the inlet side of the cooling device, and a porous direct injection nozzle may be adopted on the outlet side of the cooling device.

In addition, in a cooling line after hot rolling of a hot-rolled steel strip, a plurality of cooling devices equipped with headers for supplying cooling water to the upper surface of the hot steel plate are provided in the conveying direction of the steel plate at predetermined intervals. ing. In such a case, the following can be considered as a deployment form of the draining device of the present invention.
(A) A draining device is arranged on the upstream side and the downstream side of each cooling device provided with a cooling line.
(B) A draining device is arranged on the upstream side of the cooling device located on the most upstream side of the cooling line and on the downstream side of the cooling device located on the most downstream side.
(C) A draining device is arranged on the upstream side and the downstream side of one cooling device located on the most downstream side of the cooling line.
(D) A draining device is provided on the upstream side of the cooling device located on the most upstream side of several cooling devices arranged on the most downstream side of the cooling line and on the downstream side of the cooling device located on the most downstream side. Deploy.
Therefore, in the present invention, the cooling device may refer to not only a single cooling device but also a plurality of cooling devices.

The case where this invention is applied to a hot-rolled steel strip as a hot steel plate will be described.
As shown in FIG. 3, the slab extracted from the heating furnace 7 is hot-rolled by a roughing mill 8 and a finishing mill to form a hot-rolled steel strip having a sheet thickness of 6 mm and a product width of 2300 mm, and then cooled. The hot-rolled steel strip was conveyed to the line, and during that time, cooling water was supplied by the cooling device 2a to be cooled, and the coil was wound around the coil by the winder 10.
Six cooling devices having a cooling length L of 5000 mm were arranged in the cooling line, and the same draining device was installed upstream and downstream of each cooling device.
Table 1 shows the conditions and results performed.

Reference Example 1 is cooled at a water density of 2 m ³ / m ² min, and using a slit nozzle, the nozzle gap a ₁ = 1 mm, the amount of water per unit width of the nozzle Q ₁ = 600 L / min, Water was drained at an angle θ = 30 ° with the vertical downward. The ratio of the momentum per unit time and unit width (hereinafter referred to as “B / A”) in the line traveling direction of the cooling water and drained spray water was 1.7. As a result, the drainage performance is good without draining the cooling water to the outside of the draining device, that is, upstream of the draining device on the inlet side of the cooling device and downstream of the draining device on the outlet side of the cooling device. There was almost no outbreak. Therefore, the temperature difference in the width direction was as small as 13 ° C., which was very good. Here, L is liters (the same applies hereinafter).

As Reference Example 2 , cooling was performed at a water density of 3 m ³ / m ² min, and using a porous direct nozzle, the nozzle pitch l (el) = 3 mm, the number of nozzle rows n = 2, and the unit width per nozzle row Water was drained at a flow rate Q ₂ = 250 L / min, a nozzle diameter a ₂ = 6 mm, and an angle θ = 45 ° formed between the spray line of the drained spray water and the vertically downward direction. B / A was 3.6. As a result, the drainage performance was good without cooling water flowing out to the outside of the drainer, and there was almost no generation of stagnant water. Therefore, the temperature difference in the width direction was as small as 24 ° C., which was very good.

As Reference Example 3 , cooling with a water density of 4 m ³ / m ² min, using a spray nozzle,
Water was drained at l (el) = 200 mm, flow rate per nozzle Q ₃ = 50 L / min, injection pressure p = 1.5 MPa, θ = 60 °. B / A was 2.6. As a result, the cooling water did not flow out of the draining device, the draining property was good, and the stagnant water was hardly generated. Therefore, the temperature difference in the width direction was as small as 21 ° C., which was very good.

In addition, as Example 1 of the present invention , draining rolls are arranged at a gap d = 10 mm on the inlet side and the outlet side of the cooling device, cooled at a water density of 4 m ³ / m ² min, and using a spray nozzle, l (el) = 200 mm, flow rate per nozzle Q ₃ = 29 L / min, spray pressure p = 0.5 MPa, θ = 60 °.
Therefore, in the steel strip conveyance direction (downstream direction), a header having a spray nozzle and a draining roll are arranged as a draining device on the inlet side of the cooling device, and a draining roll in the steel strip conveying direction on the outlet side of the cooling device. A spray nozzle is arranged as a draining device.

In this invention example 1 , the momentum of the cooling water was reduced by the draining roll, and the momentum per unit time and unit width in the line traveling direction was 16.2 kg / s ² . B / A was 4.0. As a result, the draining water is injected by the draining roll into the cooling water leaking from the gap between the steel plate and the draining device, so that it is possible to drain the water with a smaller amount of water than in Reference Example 3 , and the cooling equipment exit side Cooling water did not leak to the outside of the water draining apparatus, draining performance was good, and there was almost no generation of stagnant water. Therefore, the temperature difference in the width direction was as small as 14 ° C., which was very good.

On the other hand, as Comparative Example 1, cooling was performed at a water density of 4 m ³ / m ² min, and using a spray nozzle by the draining method described in Patent Document 1, l (el) = 800 mm, Q ₃ = 138 L / min, p = 1 MPa, θ = 60 °, drained, and side spray was sprayed from both ends of the hot steel sheet at 1100 L / min, p = 1 MPa on the outside. As a result, a part of the cooling water flowed out from the position between the nozzles. In the subsequent side spray, the water that flowed out to the end of one of the hot steel plates was swept away, but a part of the spray water of the side spray bounced off the side guide of the production line and joined with the water that flowed out, and the side spray position 30m downstream from the top of the steel strip. At that time, the temperature difference in the width direction was 157 ° C., and the desired mechanical properties of the steel strip were not obtained.

Further, as Comparative Example 2, cooling was performed at a water density of 4 m ³ / m ² min, and using a spray nozzle by a draining method described in Patent Document 2, l (el) = 800 mm, Q ₃ = 130 L / min, p Drained at = 0.9 MPa and θ = 60 °. As a result, draining became possible, but the water jetted from the draining device forced the cooling water to flow to one end, and the temperature in the width direction and width direction until the cooling water flowed down to one side edge. The difference was 65 ° C., and the desired mechanical properties of the hot-rolled steel strip could not be obtained.

As Comparative Example 3, cooling with a water density of 2 m ³ / m ² min, using a slit nozzle,
Water was drained at a ₁ = 1 mm, Q ₁ = 300 L / min, and θ = 30 °. B / A was 0.4. As a result, since the momentum of the drained spray water is small, partial drainage failure occurs, the temperature difference in the width direction becomes 187 ° C., and the desired hot rolled steel strip mechanical properties cannot be obtained.

As Comparative Example 4, the sample was cooled at a water density of 2 m ³ / m ² min, and drained at a ₁ = 1 mm, Q ₁ = 1200 L / min, θ = 30 ° using a slit nozzle. B / A was 6.7. As a result, the drainage was good because the momentum on the side opposite to the line direction of the spray water of the drainer was too great, but the hot steel plate was strongly cooled by the drainer spray itself, and the temperature difference in the width direction became 67 ° C. The mechanical properties of the desired hot steel sheet could not be obtained.

Furthermore, as Comparative Example 5, the water density was cooled at 3 m ³ / m ² min, and using a spray nozzle, l (el) = 200 mm, Q ₃ = 50 L / min, p = 1.5 MPa, θ = 20 ° Drained. B / A was 1.5. Although the cooling water leaked from the cooling facility was drained, since θ is as small as 20 °, after a portion of the drained jet water collides with the hot-rolled steel strip, it flows in the line traveling direction as a back flow, Since it stayed, the temperature difference in the width direction was 90 ° C., and the desired mechanical properties of the hot steel sheet could not be obtained.

1: Hot steel plate, hot rolled steel strip 2a: Cooling device 2b: Cooling header 3a: Cooling water staying on the upper surface of the hot steel plate from the cooling device 3b: Cooling water sprayed from the cooling device 4: Drainage device (header)
5: Draining water, draining fluid 6: Draining roll 7: Heating furnace 8: Rough rolling mill 9: Finish rolling mill 10: Winding machine 11: Side spray

Claims (8)

  A draining device for an upper surface of a hot steel plate disposed upstream and downstream of an inlet side of the cooling device, the drainer device being provided with a header provided with a nozzle for injecting drain water on the upper surface of the hot steel plate, and being cooled more than the header It consists of a draining roll arranged close to the upper surface of the hot steel plate, close to the device, and the unit time of the draining water and the momentum per unit width of the cooling water in the gap between the draining roll and the hot steel plate. Maintaining within a range of 1.5 to 5 times the momentum per width, spraying drain water from the nozzle in the direction orthogonal to the width direction of the hot steel sheet and over the entire width of the hot steel sheet, and entering the cooling device A draining device for the upper surface of the hot steel sheet disposed on the inlet side upstream and outlet side of the cooling device, wherein the cooling water can be prevented from flowing out to the upstream side and the downstream side of the outlet side. Wherein characterized in that it has an angle of 30 to 70 ° jetting direction of draining water sprayed from the draining device provided entry side upstream and delivery side downstream of the cooling device relative to the vertically downward, to claim 1 The draining device of the hot steel plate upper surface arrange | positioned at the inlet side upstream and outlet side downstream of the cooling device of description . The inlet side of the cooling device according to claim 1 or 2, wherein a nozzle of at least one draining device of the draining device provided upstream and downstream of the inlet side of the cooling device is a slit type nozzle. A draining device for the upper surface of the hot steel plate disposed upstream and downstream of the delivery side. The draining device of at least one of the draining devices provided on the upstream side and the downstream side of the cooling device is composed of one or more headers having porous direct injection nozzles, the nozzles having a hole diameter of 1 to 6 mm, and a pitch The water draining device for the upper surface of the hot steel sheet disposed on the inlet side upstream side and the outlet side downstream side of the cooling device according to claim 1 , wherein is 10 times or less of the hole diameter. The draining device of at least one of the draining devices provided upstream and downstream of the cooling device comprises a header provided with a plurality of spray nozzles, and spreads the draining water (spray water) sprayed from the nozzles. The cooling according to claim 1 or 2, wherein the angle is 40 to 90 °, and the width direction injection region on the upper surface of the hot steel sheet overlaps with the drain water (spray water) of the adjacent nozzle by 30% or more. A draining device for the upper surface of the hot steel sheet disposed upstream and downstream of the apparatus.   It consists of a header provided with a nozzle for injecting drained water on the upper surface of the hot steel plate on the inlet side upstream and outlet side downstream of the cooling device, and a draining roll disposed near the upper surface of the hot steel plate closer to the cooling device than the header. Disposing the draining device, the unit time of draining water, the momentum per unit width, the range of 1.5 to 5 times the unit time, the momentum per unit width of the cooling water in the gap between the draining roll and the hot steel plate Maintained inside, spraying drain water from the nozzle in a direction perpendicular to the width direction of the hot steel sheet and over the entire width of the hot steel sheet, and supplying cooling water to the upstream side on the inlet side and the downstream side on the outlet side of the cooling device. A method of draining the upper surface of the hot steel sheet, characterized in that it is possible to prevent spillage. A method for draining an upper surface of a hot steel sheet, wherein the water draining apparatus according to any one of claims 1 to 5 is used in a production line for a hot steel sheet having a cooling device. The cooling equipment of the hot-steel plate which consists of the cooling device which cools a hot-steel plate, and the draining device as described in any one of Claims 1-5 .

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