Method for cooling coiled steel sheet, method for manufacturing coiled steel sheet, and cooling equipment for coiled steel sheet

Abstract

To provide a cooling method of a coil form steel plate in which wetting suppression of a surface of the coil form steel plate can be compatible with improvement of cooling performance for the coil form steel plate so that rust of the coil form steel plate can be suppressed and the coil form steel plate can be cooled at a high efficiency, a manufacturing method of the coil form steel plate, and a cooling facility of the coil form steel plate.SOLUTION: A cooling method of a coil form steel plate comprises the steps of: injecting cooling mist through a cooling mist generator 1; and sucking air which is cooled by evaporation of the cooling mist injected by the cooling mist generator 1 through a cooling fan 2 to blow the air into the coil form steel plate S placed on a cooling bed CF.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a method for cooling a coiled steel sheet, a method for manufacturing a coiled steel sheet, and a cooling facility for a coiled steel sheet. [Background technology]

[0002] In the manufacture of coiled steel sheets, hot rolling (hot rolling) or cold rolling (cold rolling) is carried out. Among these, when manufacturing hot-rolled steel sheets, for example, a slab is first heated to a predetermined temperature in a heating furnace, and the heated slab is rolled in a rough rolling mill to form a rough bar. Next, this rough bar is passed through a continuous hot finishing rolling mill consisting of multiple rolling stands to form a hot-rolled steel sheet of a predetermined thickness.

[0003] The hot-rolled steel sheet discharged from the continuous hot finishing rolling mill is cooled by cooling water supplied from above and below the cooling device installed on the run-out table, and then wound up by a winding machine to become a coiled hot-rolled steel sheet. The coiled hot-rolled steel sheet is then stored.

[0004] On the other hand, in the case of cold-rolled steel sheets, the hot-rolled steel sheets coming out of the continuous hot finishing mill are subjected to various processes such as pickling, annealing, and cold rolling to become cold-rolled steel sheets. The cold-rolled steel sheets are also wound up by a winding machine to become coiled cold-rolled steel sheets. Such coiled cold-rolled steel sheets are also stored in this state.

[0005] In this way, various steel sheets are wound up into a coil shape during storage. Incidentally, the temperature of various steel sheets in such a wound state is, for example, 500 to 650°C in the case of coiled hot-rolled steel sheets, and below this temperature in the case of coiled cold-rolled steel sheets. However, they cannot be shipped or sent to the next process in this temperature state. Therefore, they are cooled to room temperature in the coil storage area where these coiled steel sheets are stored (hereinafter, such storage area will be referred to as "cooling bed" as appropriate) before being transported and shipped.

[0006] A large amount of coiled steel sheets are placed on the cooling bed and cooled. Therefore, it is inevitable that coiled steel sheets at high temperatures are placed around the coiled steel sheets at high temperatures. In this case, the temperature around each coiled steel sheet is high. This reduces the cooling efficiency of the coiled steel sheets, and it may take, for example, 3 to 5 days to complete cooling of the coiled steel sheets.

[0007] As a result, the area required to store the coiled steel sheet for use as a cooling bed must be large. In addition, the cooling time required increases the time it takes to ship the coiled steel sheet. Furthermore, the cooling time also causes problems such as a shortage of space to store the coils for the cooling bed and an increase in coil inventory.

[0008] In order to shorten the cooling time of the coiled steel sheet, various methods of spraying cooling water on the coiled steel sheet have been proposed. However, when cooling water is sprayed on the coiled steel sheet when the surface temperature of the coiled steel sheet is 100°C or less, such as in the case of a coiled cold-rolled steel sheet, the cooling water does not evaporate easily. Therefore, the surface of the coiled steel sheet becomes wet with water, and if it is left as it is, rust may occur on the surface.

[0009] If rust occurs on the coiled steel sheet, its appearance is marred, and the coiled steel sheet cannot be shipped as a product. Even if cooling water is not sprayed, condensation may form on the coiled steel sheet, especially in the seasons from winter to early spring when the outside temperature is low, and condensation may cause rust.

[0010] Therefore, various measures for cooling the steel sheet are disclosed in the following Patent Documents 1 to 4. For example, as in the technology described in Patent Document 1, a water-cooling method for a hot-rolled coil is proposed in which the temperature and humidity around the coil are measured and the amount of cooling water sprayed to cool the coil is controlled so that the surface of the hot-rolled steel sheet constituting the coil does not get wet.

[0011] On the other hand, the technique described in Patent Document 2 also proposes a cooling method for hot-rolled coils in which cooling nozzles are arranged on both end faces of each coil in the width direction, and cooling is performed from both sides using the respective cooling nozzles.

[0012] Furthermore, as in the technology described in Patent Document 3, a cooling method for a coiled hot-rolled steel sheet has also been proposed in which, when cooling the coiled steel sheet after it has been wound by a winding machine installed in a hot rolling line, cooling is performed by intermittently spraying cooling mist onto both widthwise ends of the coiled steel sheet.

[0013] In addition, the technology described in Patent Document 4 is a metal coil cooling method in which mist is sprayed from a mist nozzle onto a filter installed at the inlet of a duct when cooling a metal coil after it has been wound by a winder installed in a hot rolling line. At this time, the filter prevents the mist from entering the duct, and a blower mixes the mist with outside air and blows the moist air onto the coil to cool it. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Publication No. 57-134207 [Patent Document 2] Japanese Patent Application Publication No. 5-177240 [Patent Document 3] JP 2013-188753 A [Patent Document 4] JP 2011-167736 A Summary of the Invention [Problem to be solved by the invention]

[0015] However, in the water-cooling method of the hot-rolled coil described in Patent Document 1, cooling water is sprayed onto the coil from the ceiling of the coil storage area, which is far away from the coil, resulting in a problem that the coil cooling capacity is low and the coil cannot be cooled efficiently.

[0016] In addition, the water-cooling method for hot-rolled coils described in Patent Document 2 only uses one cooling nozzle on each of both widthwise end faces of a single hot-rolled coil. Therefore, minute droplets (hereinafter, such "minute droplets" will be referred to as "mist" as appropriate) coming out of the cooling nozzle do not spread sufficiently over both widthwise end faces of the hot-rolled coil. In other words, since the cooling area is small, it is difficult to cool the entire hot-rolled coil. As a result, the water-cooling method for hot-rolled coils described in Patent Document 2 has a problem of reduced coil cooling efficiency.

[0017] Here, in order to improve the cooling capacity for the coiled steel sheet, it is important to increase the spray flow rate of the mist per unit area (hereinafter referred to as "water volume density" where appropriate). However, when the water volume density is increased, the mist becomes difficult to evaporate due to an increase in humidity around the coiled steel sheet and a decrease in the temperature of the coil surface.

[0018] As a result, the mist that does not evaporate is likely to adhere to the coil. In particular, when the temperature of the surface of the coiled steel sheet is below 100°C, the mist that adheres to the coil is unlikely to evaporate, and the coil surface is likely to remain wet, which may induce rust.

[0019] In order to prevent the coil surface from getting wet during water cooling, it is believed that using mist with small particle size is effective because the smaller the particle size of the mist, the smaller the amount of heat required for evaporation, making it easier to evaporate.

[0020] On the other hand, if the particle size of the mist is made smaller, the mist may be diffused by the influence of the wind around the coiled steel sheet, and the mist may easily miss the coiled steel sheet to be cooled. In addition, the spray distance from the mist nozzle to the coil becomes shorter, which may cause a problem that the sprayed mist may not reach the coiled steel sheet in the first place.

[0021] Here, the cooling method for a coiled hot-rolled steel sheet described in Patent Document 3 constantly sprays cooling mist from a mist nozzle onto the coiled steel sheet, and also uses an oscillating blower to carry the cooling mist on an air current and intermittently blow it onto the width direction ends of the coiled steel sheet.

[0022] However, even with this method, there is a possibility that the coiled hot-rolled steel sheet is not cooled properly due to the above-mentioned problems. Moreover, this method may lead to an increase in humidity in the surroundings other than the coiled steel sheet being cooled. In particular, the coil that has been cooled by the above-mentioned cooling method for the coiled hot-rolled steel sheet is condensed, which increases the risk of rusting of the coil.

[0023] In the metal coil cooling method described in Patent Document 4, the mist reaches the metal coil through a filter, but depending on the particle size of the mist, the mist does not evaporate sufficiently and water or the like adheres to and condenses on the filter, making it wet. Also, the cooling bed may be humidified by passing air through a wet filter.

[0024] Furthermore, the heat of vaporization of the mist lowers the air temperature, making it humid and cold, increasing the risk of condensation inside the duct and on the coil surface. It is true that humidity and temperature measurements are taken and the mist nozzle is controlled on and off based on those measurements, but the filter may get wet even after the mist nozzle stops spraying, so the control response is poor and the risk of condensation cannot be sufficiently suppressed.

[0025] In addition, if the duct is long and the route is complicated, humidity distribution will occur within the duct, making humidity control complicated. Therefore, ducts through which moist air passes require rust prevention treatment, which requires a high installation and maintenance burden.

[0026] The present invention has been made with attention to the above-mentioned points, and aims to provide a cooling method for a coiled steel plate, a manufacturing method for a coiled steel plate, and cooling equipment for a coiled steel plate, which make it possible to achieve both suppression of wetting of the surface of the coiled steel plate and improvement of the cooling capacity of the coiled steel plate, and which can cool the coiled steel plate highly efficiently without causing rust on the coiled steel plate. [Means for solving the problem]

[0027] The cooling method for a coiled steel sheet according to an embodiment of the present invention includes: (1) Located indoors, The method includes the steps of: spraying cooling mist from a cooling mist generating device; and sucking in air cooled by evaporation of the cooling mist sprayed by the cooling mist generating device and blowing the air onto the coiled steel sheet placed on the cooling bed, and the cooling mist generating device is disposed behind the direction of air blown by the cooling fan onto the coiled steel sheet. At a distance according to the particle diameter of the cooling mist are placed.

[0028] In the above-mentioned (1) method for cooling a coiled steel sheet in the embodiment of the present invention, (2) the cooling mist sprayed by the cooling mist generator has a particle diameter of 40 μm or less.

[0029] Furthermore, in the cooling method for the coiled steel plate of the above (1) or (2) in the embodiment of the present invention, after the step of the cooling fan blowing air onto the coiled steel plate, the method includes a step of exhausting the air around the coiled steel plate, including the gas blown onto the coiled steel plate by the cooling fan, to outside the cooling bed.

[0030] Moreover, the above-mentioned coiled steel sheet cooling methods (1) to (3) in an embodiment of the present invention further include a step (4) of providing a measuring device for detecting the condition of the coiled steel sheet and / or the cooling bed, and controlling the cooling mist generator and / or the cooling fan based on the conditions measured by the measuring device.

[0031] The manufacturing method of coiled steel plate according to the above (1) to (4) in an embodiment of the present invention comprises: (5) a step of spraying cooling mist by a cooling mist generator; and a step of a cooling fan sucking in air cooled by evaporation of the cooling mist sprayed by the cooling mist generator and blowing it onto the coiled steel plate placed on the cooling bed, and the cooling mist generator has a method of cooling the coiled steel plate which is arranged behind the direction of air blown by the cooling fan onto the coiled steel plate.

[0032] The method for producing a coiled steel sheet according to the above-mentioned (5) in the embodiment of the present invention is characterized in that (6) a hot-rolled steel sheet or a cold-rolled steel sheet is produced.

[0033] The cooling equipment for the coiled steel plate according to the embodiment of the present invention comprises: (7) Located indoors, The cooling bed is provided with a cooling mist generating device which sprays cooling mist, and a cooling fan which sucks in air cooled by evaporation of the cooling mist sprayed by the cooling mist generating device and blows the air onto the coiled steel sheet placed on the cooling bed. The cooling mist generating device is disposed behind the direction of air blown by the cooling fan onto the coiled steel sheet. At a distance according to the particle diameter of the cooling mist are placed.

[0034] In the coiled steel sheet cooling equipment of the embodiment of the present invention (7), the particle size of the cooling mist sprayed by the cooling mist generator (8) is 40 μm or less.

[0035] Furthermore, the cooling equipment for the coiled steel plate of (7) or (8) in the embodiment of the present invention further includes (9) an exhaust device that exhausts the air around the coiled steel plate, including the gas blown to the coiled steel plate by the cooling fan, to the outside of the cooling bed.

[0036] The cooling equipment for the coiled steel plate according to any one of (7) to (9) above in the embodiment of the present invention (10) further includes a measuring device for detecting the condition of both or either of the coiled steel plate and the cooling bed.

[0037] The cooling equipment for coiled steel plate described in any one of (7) to (10) above in an embodiment of the present invention is characterized in that it includes (11) a control device that controls both or either of the cooling mist generator and the cooling fan based on the conditions measured by the measuring device. Effect of the Invention

[0038] The coiled steel sheet cooling method, the coiled steel sheet manufacturing method, and the coiled steel sheet cooling equipment according to the embodiments of the present invention make it possible to suppress wetting of the surface of the coiled steel sheet while improving the cooling capacity of the coiled steel sheet, and to cool the coiled steel sheet with high efficiency without causing rust on the coiled steel sheet. [Brief description of the drawings]

[0039] [Figure 1] FIG. 2 is a perspective view showing an entire building in which the coiled steel plate is cooled in the embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory front view of a building in which the coiled steel plate is cooled in an embodiment of the present invention. [Diagram 3] 1 is a table showing examples of a cooling method for a coiled steel sheet in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that, in the content described below, the coiled steel sheet to be cooled may be either a hot-rolled steel sheet or a cold-rolled steel sheet, and is not limited to either. Therefore, in the following description, no particular distinction is made and the steel sheet will simply be referred to as a "coiled steel sheet".

[0041] The cooling method for the coiled steel sheet in the embodiment of the present invention described below is used when the coiled steel sheet S is formed by winding it up on a winding machine that is attached to or installed in a hot rolling line, a cold rolling line, or other pickling or annealing equipment, and is placed on a cooling bed to be cooled.

[0042] Fig. 1 is a perspective view showing an entire building B in which a coiled steel sheet S is cooled in an embodiment of the present invention. In Fig. 1, in order to clarify the inside of the building B, the building B itself is shown by a dashed line. 。

[0043] On the other hand, Fig. 2 is an explanatory diagram showing a building B in which the coiled steel plate S is cooled in the embodiment of the present invention from the front. In Fig. 2, the building B is shown by a solid line, unlike Fig. 1. Also, the flow of air sent from a cooling fan described later toward the coiled steel plate S is shown by a broken line.

[0044] In the embodiment of the present invention, the building B is formed in a rectangular shape as shown in Figures 1 and 2. However, the structure of the building B may be any, and is not limited to the structure shown in Figure 1 etc.

[0045] As shown in Fig. 1, the building B is composed of a cooling bed CF on which the coiled steel sheet S to be cooled is placed, walls surrounding the cooling bed CF on all four sides, and a ceiling R provided at a position facing the cooling bed CF. Note that in Fig. 1 and other figures, structures that are not necessary for explaining the cooling method of the coiled steel sheet S in the embodiment of the present invention are omitted.

[0046] In Fig. 1 etc., the entire floor surface of the building B is used as a cooling bed CF for cooling the coiled steel sheet S. However, it is possible to arbitrarily set the extent to which an area of ​​the building B is used as the cooling bed CF. Furthermore, the building B itself does not have to be a building dedicated to cooling the coiled steel sheet S.

[0047] Coiled steel plates S are placed on the cooling bed CF. This is placed inside the building B in order to cool the coiled steel plates S to a desired temperature. In Fig. 1, three rows of five coiled steel plates S are placed on the cooling bed CF. However, the number of coiled steel plates S placed on the cooling bed CF can be arbitrarily set depending on the operation.

[0048] When a plurality of coiled steel sheets S are arranged between cooling equipment C such as a cooling mist generator 1 and a cooling fan 2 described below, the coiled steel sheets S are preferably spaced apart, for example, by about 1 to 2 m.

[0049] The cooling bed CF shown in Fig. 1 is shown in a state in which the direction of the rotation axis when winding the coiled steel sheet S, i.e., the coil central axis, is placed in the left-right direction in the drawing. On the other hand, the cooling bed CF shown in Fig. 2 is shown in a state in which the central axis is perpendicular to the left-right direction in the drawing. In other words, the coiled steel sheet S may be placed in either direction on the cooling bed CF.

[0050] For convenience of drawing, the size of each coiled steel sheet S placed on the cooling bed CF is the same, but the size of the coiled steel sheet S to be cooled may be any size. As described above, the coiled steel sheet S may be a coiled hot-rolled steel sheet or a coiled cold-rolled steel sheet.

[0051] In Fig. 1, cooling equipment C for cooling the coiled steel plate S is provided at a position parallel to the central axis of the coiled steel plate S, i.e., on both sides of the row in which the coiled steel plates S are arranged. The cooling equipment C is composed of at least a cooling mist generator 1 and a cooling fan 2.

[0052] First, the cooling mist generator 1 generates cooling mist to be used for cooling the coiled steel sheet S. Any liquid may be used as the cooling mist, but water is preferably used in view of the workability in the cooling bed CF, cost, ease of availability, and the like.

[0053] The method of generating the cooling mist in the cooling mist generator 1 may be either a one-fluid method or a two-fluid method. For example, when a two-fluid method is adopted, the volume ratio of the gas constituting the cooling mist to the cooling liquid (i.e., the "air-water ratio") can be set in the range of 10 to 1000, taking into consideration certain conditions.

[0054] The cooling fan 2 draws in air that has been cooled by the evaporation of the cooling mist sprayed from the cooling mist generator 1, as described below, and sends it to the coiled steel sheet S placed on the cooling bed CF. Therefore, the cooling fan 2 is disposed in front of the cooling mist generator 1, i.e., downwind, so that the air from the cooling fan 2 can be sent to the coiled steel sheet S.

[0055] The cooling fan 2 is installed at a position, for example, about 1 m away from the coiled steel plate S. If the cooling fan 2 and the coiled steel plate S are placed too close to each other, there is a risk that the cooling fan 2 will be damaged by the heat of the coiled steel plate S that is the target for cooling.

[0056] On the other hand, the distance between the cooling fan 2 and the cooling mist generating device 1 is desirably large enough to allow the cooling mist to evaporate and to prevent the cooling mist from diffusing and not being sucked in by the cooling fan 2.

[0057] That is, if the mist is sucked into the fan before evaporating and reaches the coiled steel sheet S, the risk of condensation on the coiled steel sheet S increases. On the other hand, if the distance between the cooling fan 2 and the cooling mist generator 1 is too far, some of the evaporated mist is not sucked into the cooling fan 2 and spreads around, so the evaporation effect of the mist cannot be effectively utilized. Therefore, the suitable distance varies depending on the mist particle size, and the smaller the particle size, the closer the distance is. Therefore, it is important to control the mist particle size according to the distance between the cooling fan 2 and the cooling mist generator 1. This point will be described later.

[0058] Furthermore, the cooling mist sprayed from the cooling mist generator 1 is adapted to evaporate before being sucked into the cooling fan 2. In other words, the cooling fan 2 blows a gas consisting of air cooled by the evaporation of the cooling mist and the surrounding air or gas, toward the coiled steel plate S, which is the object to be cooled.

[0059] This is because if the cooling mist sprayed from the cooling mist generator 1 is sent to the coiled steel plate S via the cooling fan 2 without evaporating, the cooling mist adhering to the coiled steel plate S increases the risk of rust occurring, especially at low temperatures.

[0060] Here, heat removal from the coiled steel plate S, i.e., cooling, is achieved by two types of heat transfer: radiation and convection. Of these, radiation is expressed as the product of the emissivity and the difference between the fourth power of the absolute temperature of the surface of the coiled steel plate S and the fourth power of the absolute temperature of the surroundings. On the other hand, convection is expressed as the product of the convection heat transfer coefficient and the difference between the surface temperature of the coiled steel plate S and the surrounding air temperature. Therefore, the effect of radiation is greater when cooling high-temperature objects, and the effect of convection is greater when cooling low-temperature objects.

[0061] In addition, when focusing on the time required for cooling the coiled steel sheet S, there is a tendency that the time required for cooling to be completed from a low temperature, particularly from 100°C or less, to a desired temperature, tends to be long. Therefore, it is important to improve the cooling capacity by convection, which has a large effect on cooling at low temperatures as described above.

[0062] Among the above mentioned conditions, the convection cooling capacity can be improved by increasing the convection heat transfer coefficient and lowering the surrounding air temperature. The convection heat transfer coefficient can be improved by installing a cooling fan, and the surrounding air temperature can be lowered by spraying cooling mist.

[0063] In this way, by increasing the convection heat transfer coefficient by the cooling fan, the evaporation rate of the condensed water can be increased, so that even if condensation occurs on the coiled steel plate S, the occurrence of rust can be suppressed.

[0064] On the other hand, experiments have shown that when the cooling mist evaporates, the latent heat of vaporization reduces the air temperature by about 5°C. In this way, the spraying of cooling mist from a cooling mist generator contributes to improving the cooling capacity of convection, especially at low temperatures.

[0065] From the above viewpoints, the method for cooling a coiled steel sheet in the embodiment of the present invention uses at least a cooling mist generator 1 and a cooling fan 2 as the cooling equipment C. Furthermore, based on the cooling concept as described above, the cooling mist sprayed by the cooling mist generator 1 is not sent to the coiled steel sheet S as it is, but the air that has been cooled by first evaporating it is sent to the coiled steel sheet S via the cooling fan 2.

[0066] By using such a cooling method, it is possible to reduce the occurrence of rust caused by the adhesion of cooling mist to the coiled steel plate S. In addition, even if condensation occurs on the coiled steel plate S, the surface of the coiled steel plate S can be prevented from becoming wet because air is blown from the cooling fan 2. In addition, because the air at a lower temperature is blown to the coiled steel plate S via the cooling fan 2, the coiled steel plate S can be cooled more effectively.

[0067] Therefore, the upper limit of the flow rate of the cooling mist sprayed from the cooling mist generator 1 is the amount at which the cooling mist can evaporate before reaching the cooling fan 2. If the flow rate of the cooling mist is too high, the relative humidity around the coiled steel plate S increases, and when the relative humidity reaches 100%, the cooling mist sprayed from the cooling mist generator 1 cannot evaporate completely.

[0068] On the other hand, if the flow rate of the cooling mist is small, the cooling capacity will be insufficient because the cooling mist will not be able to cool the air sufficiently due to the heat of vaporization caused by the evaporation of the cooling mist. Therefore, it is necessary to adjust the balance between the airflow rate of the cooling fan 2 and the amount of cooling mist sprayed by the cooling mist generator 1 to control the relative humidity in the cooling bed CF.

[0069] As described above, the method for cooling a coiled steel sheet in the embodiment of the present invention cools the coiled steel sheet S by sending air cooled by evaporation of the cooling mist sprayed from the cooling mist generator 1 to the coiled steel sheet S via the cooling fan 2. Therefore, as described above, it is preferable to adopt a distance between the cooling mist generator 1 and the cooling fan 2 according to the particle diameter of the cooling mist.

[0070] First, it is desirable that the particle diameter of the cooling mist, that is, the diameter of the droplets sprayed from the cooling mist generator 1, is 40 μm or less. If the particle diameter of the cooling mist is 40 μm or less, the cooling mist evaporates in about one second. If the particle diameter of the cooling mist is 40 μm, it is desirable that the distance between the cooling mist generator 1 and the cooling fan 2 is about 1.5 m ± 0.5 m.

[0071] On the other hand, the larger the particle diameter of the cooling mist, the longer it takes for the cooling mist to evaporate. Therefore, if the particle diameter of the cooling mist is larger than 40 μm, the efficiency of evaporation of the cooling mist is poor, and the cooling of the air by the heat of vaporization is insufficient. If the cooling mist is sucked into the cooling fan 2 without evaporating, there is a high possibility that the cooling mist will adhere to the coiled steel plate S without evaporating, increasing the risk of rust.

[0072] In contrast, for example, when the particle diameter of the cooling mist is 20 μm, it is desirable to set the distance between the cooling mist generator 1 and the cooling fan 2 to about 1 m ± 0.5 m. Of course, the particle diameter of the cooling mist may be 20 μm or less, in which case the distance between the cooling mist generator 1 and the cooling fan 2 will be closer than when the particle diameter of the cooling mist is 20 μm.

[0073] Thus, there is a correlation between the particle diameter of the cooling mist and the distance between the cooling mist generator 1 and the cooling fan 2. Therefore, when the particle diameter of the cooling mist is 20 μm to 40 μm, the distance between the cooling mist generator 1 and the cooling fan 2 is approximately 0.5 m to 2 m.

[0074] Although the particle size of the cooling mist is desirable as described above, if the ease of evaporation is taken into too much consideration, the amount of cooling mist sprayed will be small, which will inevitably result in a small amount of evaporation. Therefore, in such cases, it is desirable to spray a large amount of cooling mist with a small particle size.

[0075] Furthermore, in the method for cooling the coil-shaped steel sheet S in the embodiment of the present invention, the cooling mist generator 1 intermittently sprays the cooling mist and stops spraying the cooling mist, and the spraying is controlled to be alternately repeated for a certain period of time. The spray interval can be set according to the target cooling time for the coil-shaped steel sheet S.

[0076] In this way, by alternately repeating the spraying and stopping of spraying of the cooling mist for a certain period of time, it is possible to suppress an increase in humidity around the coil-shaped steel sheet S compared to the case where spraying is continuous. More preferably, since the risk of condensation increases as the temperature of the coil-shaped steel sheet S decreases, it is possible to easily suppress rust by setting the spraying interval of the cooling mist to be longer.

[0077] When the coiled steel sheet S has reached a sufficiently low temperature and cooling has been completed, it is preferable to stop spraying the cooling mist from the cooling mist generator 1 from the viewpoints of running costs and the risk of condensation.

[0078] Here, when the cooling mist evaporates, the humidity increases, particularly around the coiled steel sheet S. If the humidity increases, condensation occurs especially when the coiled steel sheet S is at a low temperature, making it more likely to rust. Therefore, an increase in humidity is undesirable.

[0079] Since warm air rises, it is possible to suppress an increase in humidity by installing an exhaust fan on the ceiling R of the cooling floor CF and actively exhausting the air from the cooling floor CF, for example, outside of building B.

[0080] For example, when the temperature of the cooling bed CF is 40°C, the relative humidity is 90%, and the dew point is 38°C, the coiled steel plate S will condense at temperatures below 38°C. Therefore, when cooling causes the surface temperature of the coiled steel plate S to drop by 2°C relative to the temperature around the coiled steel plate S, or when the relative humidity reaches 100%, condensation will occur on the surface of the coiled steel plate S, so it is necessary to exhaust the air around the cooling bed CF to reduce the humidity.

[0081] Therefore, in the cooling equipment C for the coiled steel plate S in the embodiment of the present invention, roof fans RF are provided on the ceiling R of the building B. That is, as shown in Fig. 1 and Fig. 2, for example, three roof fans RF are provided in the building B. The number of roof fans RF to be provided can be freely set. Also, although the roof fans RF are installed in a row on the ceiling R as shown in Fig. 1, the arrangement positions of the roof fans RF can also be freely set.

[0082] As described above, taking into consideration that the heated air rises above the coiled steel plate S during cooling of the coiled steel plate S, the exhaust is not described in the embodiments of the present invention, and the roof fan RF provided on the ceiling R1 does not need to be used. In other words, it is sufficient that the exhaust device is installed above the upper ends of the coiled steel plates S arranged on the cooling bed CF.

[0083] In Figure 2, the dashed lines show the movement of wind when the cooling equipment C consisting of the cooling mist generator 1, the cooling fan 2, and the roof fan RF is in operation. As shown in Figure 2, the cooling mist generator 1 and the cooling fan 2 are arranged on both sides of the coiled steel plate S placed in a row.

[0084] The cooling mist sprayed from the cooling mist generator 1 evaporates between the cooling mist generator 1 and the cooling fan 2, thereby cooling the surrounding air. The cooling fan 2 sucks in this cooled air and blows it out together with the surrounding gas, sending it to the coiled steel plate S. The gas sent from the cooling fan 2 toward the coiled steel plate S is exhausted from the roof fan RF to the outside of the building B, including the air around the cooling bed CF, as shown by the dashed arrow in Figure 2.

[0085] Furthermore, the cooling mist generator 1 and cooling fan 2 described above can be controlled based on information obtained by grasping the conditions inside building B using a measuring device 3. Figures 1 and 2 show a state in which a thermometer and hygrometer are installed on the wall of building B as an example of the measuring device 3.

[0086] If the temperature and humidity can be grasped in this way, the dew point can be estimated. This makes it possible to grasp the risk of condensation occurring on the coiled steel sheet S, and to control the cooling equipment C, such as the cooling mist generator 1 and the cooling fan 2, by means of a control device (not shown). In addition, based on information such as temperature grasped by the thermo-hygrometer, it becomes possible to remove the coiled steel sheet S from the cooling bed CF before condensation occurs.

[0087] Since a large number of coiled steel sheets S are placed on the cooling bed CF, it is preferable to use, for example, a radiation thermometer as the measuring device 3 used for temperature measurement. Also, a two-dimensional radiation thermometer may be used to measure the temperatures of a plurality of coiled steel sheets S with one device. The measurement position is preferably a surface perpendicular to the central axis of the coiled steel sheet S, i.e., a surface formed by its widthwise ends.

[0088] This is because the surface of the coiled steel sheet S that is made up of the width ends has poor thermal conductivity because the steel sheets are stacked in the radial direction. In addition, the outermost and innermost circumferences may be loosely wound, which may further worsen thermal conductivity. When thermal conductivity is poor like this, it is difficult to transmit the temperature from the inside, making it necessary to underestimate the temperature, making accurate measurement difficult. Therefore, we measure the surface that is made up of the width ends, which allows us to reliably measure the temperature of the coiled steel sheet S without such problems.

[0089] Also, here, a thermometer and hygrometer are given as an example of the measuring device 3. However, for example, with regard to the occurrence of condensation, a video camera may be installed as the measuring device 3 and the coiled steel plate S may be directly observed to determine whether condensation has occurred.

[0090] Next, examples of the method for cooling the coiled steel sheet S using the cooling equipment C such as the cooling mist generator 1 described above will be described. Fig. 3 is a table showing examples of the method for cooling the coiled steel sheet S in the embodiment of the present invention.

[0091] As shown in the table in Figure 3, eight working examples are listed vertically, and five comparative examples are listed for comparing these working examples. Twelve conditions are listed horizontally: "Cooling method," "Number of fans (units / row)," "Number of coils (pieces / row)," "Use of roof fan," "Mist particle diameter (μm)," "Filter (presence / absence)," "Intermittent pattern," "Installation of radiation thermometer," "Installation of cooling bed thermometer / hygrometer," "Average cooling bed temperature (℃)," "Average relative humidity (%)," and "Coil recovery temperature (℃)." Meanwhile, the two items of "Cooling time" and "Rust" show the results of the implementation.

[0092] First, there are two types of "cooling method", and all of the examples employ a cooling method using a cooling mist generator 1 and a cooling fan 2. On the other hand, the comparative examples basically use atmospheric cooling, and do not use the cooling mist generator 1 or the cooling fan 2. However, comparative example 5 is an example in which the cooling mist generator 1 and the cooling fan 2 are used with a filter between them.

[0093] Therefore, the condition "number of fans (units / row)" is a condition that pertains to all of the examples and comparative example 5. This condition indicates how many cooling fans 2 are arranged in one row when multiple coil-shaped steel plates S are lined up. In most cases, it is "2 units," but in example 2, it is "1 unit," and in example 8, it is "4 units."

[0094] "Roof fan used" indicates whether or not a roof fan RF provided on the ceiling R was used to cool the coiled steel sheet S. Among the comparative examples, Comparative Example 4 used a roof fan RF, and Comparative Example 5 did not use a roof fan RF. On the other hand, among the examples, only Example 5 did not use a roof fan RF, and the other examples used a roof fan RF.

[0095] "Mist particle diameter (μm)" is a condition set for the particle diameter of the cooling mist sprayed from the cooling mist generator 1. As is clear from the table in Fig. 3, in many cases the particle diameter was set to "20 μm," but in Comparative Example 5 and Example 3 it was set to "40 μm," and in Example 4 it was set to "50 μm."

[0096] "Filter (with or without)" indicates whether or not a filter is placed between the cooling mist generator 1 and the cooling fan 2. Here, a filter is placed only in Comparative Example 5, and a filter is not placed in the other Comparative Examples and all Examples.

[0097] The "intermittent pattern" refers to a pattern in which spraying and stopping are alternately repeated when spraying cooling mist from the cooling mist generator 1, and an "spray time (s)" and a "stop time (s)" are set in Comparative Example 5 and each Example. That is, except for Example 7, the "spray time" is "20 s" and the "stop time" is "10 s." On the other hand, for Example 7, both the "spray time" and the "stop time" are "20 s," and the "stop time" is set longer than the other Examples.

[0098] In addition, the conditions of "mist particle diameter (μm)", "intermittent pattern", "radiation thermometer installation", and "cooling bed temperature and humidity meter installation" described below are not shown in Comparative Examples 1 to 4 except Comparative Example 5, in which cooling is performed by air cooling and the cooling mist generator 1 and the cooling fan 2 are not used.

[0099] "Radiation thermometer installed" indicates whether or not a radiation thermometer was installed in building B as the above-mentioned measuring device 3. In the comparative examples, a radiation thermometer was not installed in any of the examples except for Comparative Example 5. In contrast, a radiation thermometer was installed in all of the examples except for Example 6.

[0100] "Cooling bed thermometer / hygrometer installation" indicates whether or not a thermometer / hygrometer was installed on the cooling bed CF. It was installed in all examples except for Example 7. On the other hand, in the comparative examples, a cooling bed thermometer / hygrometer was installed in Comparative Example 4 and Comparative Example 5, but not in the other comparative examples.

[0101] The conditions of "cooling bed average temperature (℃)", "average relative humidity (%)", and "coil recovery temperature (℃)" indicate the basic conditions when conducting the experiments of the examples and comparative examples. The following conditions are set when conducting these experiments.

[0102] That is, the cooling start temperature of the coiled steel plate S was 600°C, and the unit weight of the coiled steel plate S was 20 tons / piece. Furthermore, five coiled steel plates S were placed in one row, the temperature of the cooling bed CF was 30°C, and the relative humidity was 80%. Water was used as the raw material for the cooling mist, and its temperature was 30°C. Finally, the cooling of the coiled steel plate S was stopped when the surface temperature of the coiled steel plate S reached 50°C.

[0103] Therefore, among the various conditions mentioned above, the values ​​of the "average cooling bed temperature (°C)," "average relative humidity (%)," and "coil recovery temperature (°C) (cooling stop temperature)" were appropriately changed in the examples and comparative examples to understand the changes.

[0104] The above-mentioned conditions were set for each example and comparative example, and the results of the experiment are shown in the items "cooling time" and "rust". The former shows the "effect of shortening the cooling time" and the latter shows the "effect of shortening the cooling time". 、 The effects are shown in four types: double circle, circle, triangle, and cross.

[0105] Among these, the effect indicated by a double circle is "when the cooling time is shortened by more than 2 days compared to the cooling time when the coiled steel sheet is allowed to cool in the air." A circle indicates "when the cooling time is shortened by more than 1.5 to 2 days compared to the cooling time when the coiled steel sheet is allowed to cool in the air."

[0106] On the other hand, triangles indicate cases where the cooling time was shortened by more than 1 to 1.5 days compared to the cooling time required by air cooling of coiled steel sheets. Crosses indicate cases where the cooling time was shortened by less than 1 day compared to the cooling time required by air cooling of coiled steel sheets.

[0107] Next, the effect indicated as "rust" shows the result of "evaluation based on rust formation after cooling." This effect is also evaluated in the same way as the "cooling time" above. 、 The effects are shown in four types: double circle, circle, triangle, and cross.

[0108] First, the effect shown by the double circle indicates that "no rust has occurred along the entire length and width of the coiled steel plate." The circle indicates that "rust has occurred over an area of ​​less than 5% of the entire length and width of the coiled steel plate."

[0109] On the other hand, a triangle indicates that "rust has occurred over an area less than 10% of the total length and width of the coiled steel plate," while a cross indicates that "rust has occurred over an area of ​​10% or more of the total length and width of the coiled steel plate."

[0110] Looking at the above conditions and results, the comparative examples were given a double circle for rust occurrence, meaning that there were cases where no rust occurred on the coiled steel plate S. However, all of the comparative examples 1 to 4 involved air cooling without using the cooling mist generator 1 or the like, and so the cooling time was long. As a result, all of these comparative examples were given a "X" for the cooling time.

[0111] As described above, Comparative Example 5 is the only one among the Comparative Examples and Examples that is equipped with a filter. Looking at the results of Comparative Example 5, as in the Examples, cooling was performed using the cooling mist generator 1, etc., so the result of "cooling time" was marked with a double circle.

[0112] However, the result for "rust" was "X", which indicates that "rust has occurred in an area of ​​10% or more of the total length and width of the coiled steel plate", just like in Comparative Example 2. This is thought to be due to the reduced responsiveness of humidity control caused by the installation of the filter.

[0113] In addition, since the roof fan RF was not used in Comparative Example 5, proper exhaust was not achieved, which resulted in an increase in humidity in the cooling bed CF (the average relative humidity in the table in Figure 3 is 90%), and this is also thought to be one of the factors that caused rust to form over a wide area of ​​the coil-shaped steel plate S.

[0114] In contrast, looking at the eight examples, cooling was performed using the cooling mist generator 1, etc. As a result, at the very least, the result was that "the cooling time was shortened by more than 1.5 to 2 days compared to the cooling time required by cooling the coiled steel plate in the air (circle)."

[0115] That is, first, for four examples, double circles were obtained. On the other hand, for the remaining four examples, the result was a circle, not a double circle. Of the examples that were circle-like, it is believed that this result was obtained for example 2 because the number of cooling fans 2 was one per row, and for example 3, the particle diameter of the cooling mist sprayed from the cooling mist generator 1 was set to "40 μm." Also, it is believed that the particle diameter of the cooling mist in example 4 was too large, similar to example 3.

[0116] On the other hand, a radiation thermometer was not installed in Example 6. In this case, the temperature of the coiled steel sheet S was unknown, and this was thought to be the reason for the delay in recovering the coiled steel sheet S from the cooling bed CF.

[0117] On the other hand, regarding the occurrence of rust, four of the eight examples were marked with double circles, but two were marked with triangles. The triangles were in Examples 4 and 5. In Example 4, the particle diameter of the cooling mist sprayed from the cooling mist generator 1 was larger than in the other examples, and was larger than the above-mentioned preferable particle diameter.

[0118] That is, in the case of Example 4, the particle diameter of the cooling mist was large at 50 μm, and it is believed that a portion of the cooling mist did not evaporate after being sprayed from the cooling mist generator 1 and before being sucked into the cooling fan 2, and instead adhered to the coil-shaped steel plate S as it was.

[0119] In the case of Example 5, among the above-mentioned conditions, the roof fan RF was not used, and therefore, it is considered that the humidity of the cooling bed CF increased due to insufficient exhaust (the average relative humidity in the table of FIG. 3 is 90%), and rust occurred on the coiled steel plate S.

[0120] Example 7 received a perfect score for rust occurrence. In Example 7, a thermometer and hygrometer were not installed on the cooling bed CF. As a result, it was not possible to optimize the control of the intermittent pattern of the roof fan RF and the cooling mist, which led to an increase in humidity on the cooling bed CF, which is thought to have resulted in rust occurrence on the coiled steel plate S.

[0121] On the other hand, both Example 1 and Example 8 were able to obtain double circles for the cooling time and rusting effects. Therefore, it was possible to ship high-quality coiled steel sheets in a short time. Furthermore, by installing a radiation thermometer and a thermometer / hygrometer on the cooling bed, it was possible to grasp the surface temperature of the coiled steel sheets and the temperature and humidity of the cooling bed, and thus it was possible to optimize the shipping timing of the coiled steel sheets and accurately predict condensation, thereby obtaining further benefits.

[0122] Moreover, compared to Comparative Example 5, none of Examples 1 to 8 used a filter. Therefore, it is believed that it was possible to prevent the mist sprayed by the cooling mist generator 1 from adhering to the filter and leaving it wet, i.e., in a humid state. Therefore, the responsiveness of humidity control was good and the risk of condensation was reduced, so that the effectiveness against rust was also generally good.

[0123] In the above-mentioned embodiments, the cooling start temperature of the coiled steel sheet S is set to 600°C, but the effect of the invention does not change significantly depending on the cooling start temperature. In addition, the temperature of the water supplied to the cooling mist generating device 1 is set to 30°C, but a lower temperature provides a higher cooling effect. In addition, if the water temperature exceeds the cooling target temperature of 50°C, it becomes difficult to cool the water to the cooling stop temperature, so in this case, the water temperature is preferably 40°C or lower.

[0124] As described above, by using the coiled steel sheet cooling method, the coiled steel sheet manufacturing method, and the coiled steel sheet cooling equipment in the embodiments of the present invention, it is possible to suppress wetting of the surface of the coiled steel sheet while improving the cooling capacity of the coiled steel sheet, and the coiled steel sheet can be cooled highly efficiently without causing rust on the coiled steel sheet.

[0125] Based on the above-described embodiment, when starting to cool the coil-shaped steel plate S, more reliable cooling can be achieved by determining the spray volume and air volume of the cooling equipment C, such as the cooling mist generator 1 and the cooling fan 2, and then performing cooling.

[0126] As described above, the present invention can be applied to cold-rolled steel sheets having stricter surface quality requirements by controlling temperature and humidity more strictly.

[0127] Furthermore, in the above-described embodiment, the coiled steel sheets are arranged in one row of five sheets, and one or two cooling devices are installed per row. However, the row may be divided according to the number of coiled steel sheets per row, and additional cooling devices may be installed midway between the divisions.

[0128] For example, although the cooling mist generator 1 and the cooling fan 2 have been described as separate devices, they may be integrated into one structure. Of course, even in this case, the gas blown from the fan to the coiled steel plate S is air that has been cooled by the evaporation of the cooling mist.

[0129] The embodiments of the present invention described above are merely examples of the present invention. Various modifications or improvements can be made to each of these embodiments, and such modifications or improvements may also be included in the present invention. These embodiments and modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0130] 1 Cooling mist generator 2 Cooling fans 3. Measuring Equipment B building CF cooling bed RF Roof Fan S Coiled steel sheet

Claims

1. A method for cooling a room, comprising: spraying cooling mist from a cooling mist generating device disposed indoors; a cooling fan sucking in air cooled by evaporation of the cooling mist sprayed by the cooling mist generator and blowing the air onto the coil-shaped steel plate placed on a cooling bed; Equipped with A method for cooling a coiled steel plate, characterized in that the cooling mist generating device is arranged behind the direction of air blown by the cooling fan toward the coiled steel plate at a distance corresponding to the particle diameter of the cooling mist.

2. 2. The method for cooling a coiled steel plate according to claim 1, wherein the cooling mist has a particle diameter of 40 μm or less.

3. After the step of blowing air onto the coiled steel sheet by the cooling fan, 2. The method for cooling a coiled steel plate according to claim 1, further comprising a step of exhausting the air around the coiled steel plate, including the gas blown to the coiled steel plate by the cooling fan, to the outside of the cooling bed.

4. A measuring device is provided for detecting the state of both the coiled steel plate and the cooling bed, or one of the two, 2. The method for cooling a coiled steel sheet according to claim 1, further comprising a step of controlling either or both of the cooling mist generating device and the cooling fan based on the conditions measured by the measuring device.

5. A method for producing a coiled steel sheet, comprising the method for cooling a coiled steel sheet according to any one of claims 1 to 4.

6. The method for producing a coiled steel sheet according to claim 5, characterized in that a hot-rolled steel sheet or a cold-rolled steel sheet is produced.

7. A cooling mist generating device that is arranged indoors and sprays cooling mist; a cooling fan that sucks in air cooled by evaporation of the cooling mist sprayed by the cooling mist generator and sends the air to the coiled steel plate placed on the cooling bed; Equipped with A cooling equipment for a coil-shaped steel plate, characterized in that the cooling mist generating device is arranged behind the direction of air blown by the cooling fan to the coil-shaped steel plate at a distance corresponding to the particle diameter of the cooling mist.

8. 8. The cooling equipment for a coiled steel plate according to claim 7, wherein the particle diameter of the cooling mist sprayed by the cooling mist generating device is 40 μm or less.

9. The cooling equipment for the coiled steel plate according to claim 7, characterized in that the cooling equipment for the coiled steel plate is provided with an exhaust device that exhausts the air around the coiled steel plate, including the gas blown to the coiled steel plate by the cooling fan, outside the cooling bed.

10. The cooling equipment for the coiled steel plate according to claim 8, characterized in that the cooling equipment for the coiled steel plate is provided with an exhaust device that exhausts the air around the coiled steel plate, including the gas blown to the coiled steel plate by the cooling fan, outside the cooling bed.

11. The cooling equipment for the coiled steel plate according to claim 7, further comprising a measuring device for detecting the condition of the coiled steel plate and / or the cooling bed.

12. The cooling equipment for the coiled steel plate according to any one of claims 7 to 11, characterized in that the cooling equipment for the coiled steel plate is provided with a control device that controls both or either of the cooling mist generating device and the cooling fan based on the conditions measured by the measuring device.

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