JP2003064421A - Device for cooling, heating or drying steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for cooling, heating or drying a steel strip by spraying a refrigerant or a heating medium capable of consistently passing the steel strip while preventing any fluttering or twisting phenomenon even when the shape of the steel strip is defective. SOLUTION: In the device for cooling, heating or drying the steel strip by spraying the refrigerant or the heating medium from refrigerant or heating medium spraying boxes opositely disposed on face and back sides of the steel strip, a pair of baffle plates for adequately adjusting a space between the spraying boxes facing each other, in particular, only the space in the vicinity of right and left edges of the steel strip are installed on each spraying box. By adjusting the space by the baffle plates, the flow of the refrigerant or the heating medium is changed on the face and back sides of the steel strip, and the steel strip is consistently passed by generating the differential pressure between the face and back sides of the steel strip at the edges of the steel strip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device, a heating (preheating) device or a drying device for steel strips used in continuous annealing equipment, hot dip coating equipment and the like.

[0002]

2. Description of the Related Art Conventionally, as a cooling device used in continuous annealing equipment, there is a technique disclosed in Japanese Patent Publication No. 2-16375. As shown in FIG. 9, in this technique, in a furnace body 11 of a vertical continuous annealing furnace, a pair of refrigerant spraying boxes 1 having a plurality of nozzles 5 are provided with a predetermined interval on both sides of a steel strip 3. Installed by opening the steel strip 3 from the nozzle 5.
The steel strip 3 is cooled to a predetermined temperature by spraying a coolant toward the. The refrigerant after being blown onto the steel strip 3 is sucked through the suction port 10 installed at a predetermined position of the furnace body 11, and is guided through the duct 8, the heat exchanger 9, the blower 4 and the duct 12 having a Y-shaped cross section. Back to the spray box 1 via
Used in circulation.

By the way, when the steel strip to be passed through the steel strip is deformed, such as C warped or meandered, the flow of the refrigerant after spraying the steel strip is unbalanced, and The fluttering that the edge part flaps and the twist phenomenon that the steel strip edge part twists occur. The conditions such as the width and thickness of the steel strip passed through the cooling device are various, but particularly in the case of a wide material or a thin material, this fluttering or twist phenomenon is likely to occur. Even when there is no defective shape of the steel strip, especially when the amount of refrigerant is large, the refrigerant after being blown to the central part of the steel strip flows to the edge side and is exhausted as it goes to the edge side of the steel strip. Therefore, the refrigerant sprayed on the edge of the steel strip is affected by the flow of the refrigerant after it is sprayed on the central part, and the pressure balance on the front and back of the steel strip edge becomes unstable, causing fluttering and twisting phenomena. It is thought to occur.

When such fluttering or twisting phenomenon of the steel strip occurs, the gap between the steel strip and the spray box of the refrigerant becomes
For example, since the distance is as small as 50 to 250 mm,
The steel strip comes into contact with the spray box, causing damage to the steel strip, and in order to avoid such damage, it is necessary to reduce the line speed or reduce the amount of refrigerant sprayed on the steel strip, which reduces production efficiency. The problem arises. Further, when this refrigerant device is applied to a hot dip plating device, for example, this cooling device is used for cooling after plating. However, when such a phenomenon occurs in the cooling device, the wiping nozzle and the steel strip for plating are used. And the distance between the steel sheet and the steel strip fluctuates, and accordingly, the amount of plating deposited on the front and back surfaces of the steel strip varies, which also causes deterioration of the plating deposition accuracy.

Therefore, for example, in Japanese Unexamined Patent Publication No. 9-241764, as shown in FIG. 10, a pair of refrigerant spray boxes 1 are arranged on the front and back surfaces of the steel strip 3 at appropriate intervals and face each other. The cross section is Y on one side in the width direction of the box 1.
In a cooling device that continuously supplies a refrigerant through a V-shaped duct 12 and cools the steel strip 3 through a nozzle 5 provided in each spray box 1, in a cooling device of the spray box 1, the side opposite to the refrigerant supply side is crossed. Install the guide plate 13 with a V-shaped surface,
A cooling device is described in which the cross sections of the refrigerant supply side and the non-supply side of the spray box 1 are formed to have substantially the same shape so as to make the flow of the refrigerant uniform.

By providing the guide plate 13 in this way,
Although it is theoretically possible to evenly distribute the refrigerant flowing to both sides of the steel strip by forming a space that is surrounded so that the cross-sections of both edges of the steel strip 3 have the same shape, Since the shape of the steel strip 3 is not constant during operation,
There may be an imbalance in the gas flow, which is considered to be caused by a defective shape of the steel strip 3. In such a case, the Y-shaped duct 12 and the guide plate 13 that surround the both edges are fixed, It was difficult to improve the unstable conveyance state of the belt 2.

Although the cooling device has been described as an example here, for example, in a preheating zone such as a continuous annealing facility, a heating device for spraying a heating medium onto the steel strip to heat the steel strip, or plating the steel strip. Also in a drying device or the like in which chromic acid treatment is performed after that, and a heating medium is sprayed on the steel strip to dry it, similar to the above-described cooling device, problems such as twisting phenomenon and fluttering of the steel strip occur. Therefore, conventionally, in order to prevent this, the line is decelerated, or the amount of the heat medium sprayed on the steel strip is reduced, or the distance between the spray box for spraying the heat medium and the steel strip is increased more than necessary. Therefore, even in the heating device and the drying device by spraying the heat medium, there is a problem that the production efficiency is lowered similarly to the cooling device. Therefore, the invention of the present application prevents fluttering and twisting even when the shape of the steel strip is poor, and constantly cools the steel strip by spraying a refrigerant or a heat medium capable of stably passing the steel strip. An object is to provide an apparatus for heating or drying.

[0008]

In a device for cooling or heating or drying a steel strip by spraying the refrigerant or the heating medium on the steel strip from a blowing box for the refrigerant or the heating medium arranged on the front and back sides of the steel strip so as to face each other. Installing a pair of baffle plates for appropriately adjusting only the gaps of the spray box arranged opposite to each other, especially the gaps near the left and right edges of the steel strip, and adjusting the gap by the baffle plates According to this, the flow of the refrigerant or the heat medium on the front and back surfaces of the steel strip is changed, and a pressure difference is generated between the front and back surfaces of the steel strip at the steel strip edge portion, so that the steel strip can be threaded stably.

Further, the pair of baffle plates located in the vicinity of the left and right edge portions of the steel strip are slidable so as to be movable in the vertical direction with respect to the facing surfaces of the spray box arranged opposite to each other. To do. The pair of baffle plates located near the left and right edges of the steel strip are each pivotally attached to the spray box at one end, and are rotatable toward the outside of the spray box. To do.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is an overall view showing a cooling device section of a vertical continuous annealing equipment, and FIG. 2 is a cross-sectional view of a refrigerant spray box of the present invention. As shown in FIG. 1, the steel strip 3 is conveyed from the upper side to the lower side or from the lower side to the upper side by a conveying roll 7 arranged above and a conveying roll 7 arranged below. On the front and back sides of the steel strip 3 conveyed up and down, a pair of refrigerant spray boxes 1 are arranged facing each other with a constant gap 6. In this embodiment, the spray boxes 1 facing each other are arranged in three stages. ing. Of course, the number of steps differs depending on the line.

As shown in FIG. 2, this spray box 1 is provided with a large number of nozzle holes 5 (may be projection nozzles), and the refrigerant pressurized by a blower (not shown) is
The refrigerant is sprayed from the nozzle hole 5 of the spray box 1 over the entire width of the steel strip 3 to cool the steel strip 3 to a predetermined temperature. By the way, this refrigerant is gas, steam, or the like. When the cooling device is installed in the furnace body like the continuous annealing equipment described in the related art, the refrigerant after being sprayed on the steel strip 3 is the same as in the case described in the related art. Is sucked from a suction port for sucking the atmosphere gas in the furnace arranged at a predetermined position, passes through the heat exchanger, is cooled to a predetermined temperature, is pressurized by a blower, and is supplied to the spray box 1. Used in circulation.

When used for cooling after plating, for example, in a hot dip galvanizing facility, the cooling device is not installed inside the furnace body and is exposed. In such a case, the steel strip 3 is used. The refrigerant after being sprayed on the air is directly emitted to the atmosphere. In any of the equipments, the refrigerant after being sprayed onto the steel strip 3 is in the vertical direction along the front and back surfaces of the steel strip 3 in the gap 6 between the pair of refrigerant spray boxes 1 and in the steel strip 3. It flows to both edges and is exhausted.

In such a cooling device, the plate conditions of the steel strip 3 to be conveyed are various, but in the case of a wide material or a thin material, a slight shape defect of the steel strip 3 causes the steel strip 3 and Since the distance to the spray box 1 differs between the front and back surfaces A and B, as a result, a difference occurs in the refrigerant flow on both sides of the steel strip 3 and the pressure on the front and back surfaces A and B of the steel strip 3 fluctuates. As a result, both edge portions of the steel strip 3 cause a fluttering or twist phenomenon, and the steel strip 3 and the refrigerant spray box 1 come into contact with each other. Even when the shape of the steel strip 3 is good, fluttering or twisting may occur especially when the amount of refrigerant is large. This is because the refrigerant after being blown to the central portion of the steel strip 3 flows toward both edge portions in the width direction of the steel strip 3 as it goes to the edge portion of the steel strip 3 and is discharged. It is considered that this is caused by the pressure fluctuation on the front and back surfaces of the steel strip 3 at the edge portion due to the collision with the refrigerant sprayed from the nozzle 5 of No. 1 to the edge portion.

Therefore, in the present invention, in order to prevent such fluttering and twisting phenomenon, as shown in the transverse sectional view of FIG. By attaching the baffle plate 2 for adjusting the gap 6 between the box 1 and the blowing box 1, it is possible to adjust the distance only between the left and right edges of the steel strip 3 in the gap. As shown in FIG. 1, the baffle plate 2 is attached over the entire length of the spray box 1 by, for example, bolts, and the baffle plate 2 faces the facing surface of the spray box 1 which is arranged to face each other according to the plate condition. It is a sliding type that can be moved in the vertical direction.

A pair of baffle plates 2 must be provided on both left and right edge portions of the steel strip 3. For example, in FIG. 2, the left side surface of the spray box 1 on the front side A of the steel strip 3 and
It is provided on the right side surface of the spray box 1 on the back surface side B of the steel strip 3 by mistake. For example, when fluttering or a twist phenomenon occurs, the pair of baffle plates 2 provided by mistake are slid toward the steel strip 3 side, respectively.
The gap between them, that is, the opening width for discharging the refrigerant from the spray box 1 is narrowed. As a result, the exhaust flow of the refrigerant on the front and back sides A and B of the steel strip 3 changes at the edge portion of the steel strip 3.

That is, the baffle plate 2 is installed on one of the pair of spray boxes 1 facing each other, and the baffle plate 2 is slid in a direction perpendicular to the facing surface of the other spray box 1.
At the left side edge portion of the front side A and the right side edge portion of the back side B where the gap portion near the edge portion is narrowed, the exhaust flow of the refrigerant flows out of the blowing box 1 after being blocked by the baffle plate 2 once. At the right edge portion of the front surface side A where the plate 2 is not installed and the left edge portion of the back surface side B, the exhaust flow of the refrigerant is not limited, and therefore flows out of the spray box 1 as it is. Steel strip 3 generated by this
A bending moment 14 is generated in the steel strip 3 due to a pressure difference between the front surface side A and the back surface side B at the edge portion of the steel strip 3 and the steel strip 3 stands still in a slightly inclined state as shown in FIG. However, this angle naturally changes depending on the bending rigidity of the steel strip 3.

The slide amount of this baffle plate 2 is
It is adjusted according to the conditions of the steel strip 3, but by appropriately adjusting the gap portion near the edge portion in this way, a bending moment 14 in a certain direction is generated in the steel strip 3 and the steel strip 3 is balanced by the pressure difference. Since the steel strip 3 is stationary in this state, it is possible to prevent fluttering or twisting in which the edge portion of the steel strip 3 vibrates in the front-back surface AB direction of the steel strip 3 and to pass the steel strip 3 in a stable state. 2 and 3, the baffle plates 2 are provided on the left side of the front side A and the right side of the back side B of the spray box 1, but the right side of the front side A and the left side of the back side B are arbitrary. You can make a difference.

Further, the baffle plates 2 may be installed at both ends of one spray box 1 of the spray boxes 1 arranged to face each other as shown in FIG. In FIG. 4, it is attached to both side surfaces of the blowing box 1 arranged on the back surface side B of the steel strip 3, and in this case, at both left and right edge portions of the steel strip back surface B,
The exhaust flow of the refrigerant is once blocked by the baffle plate 2 and then flows out of the spray box 1. On the other hand, the left and right edge portions of the front surface side A where the baffle plate 2 is not installed limit the exhaust flow of the refrigerant. Since it is not sprayed, it flows out of the spray box 1 as it is. A bending moment 14 is generated in the steel strip 3 due to the pressure difference between the front surface side A and the back surface side B at the edge portion of the steel strip 3 generated in this way, and in this case, the steel strip 3 has a bending moment 14 as shown in FIG. Both edges are front side A
It stopped in the state of a little C warp which approached. However, this C warp amount naturally changes depending on the bending rigidity of the steel strip 3.
In FIG. 4, the baffle plates 2 are attached to both sides of the back side B spray box 1, but the front side A spray box 1
Of course, it doesn't matter if they are attached to both sides.

Next, another embodiment of this baffle plate will be described. FIG. 5 is a cross-sectional view of a spray box showing another embodiment, and FIG. 6 is a side view of the spray box. In this embodiment, the baffle plate 2 is of a rotating type, and the pair of baffle plates 2 located near the left and right edge portions of the steel strip 3 are fixed plates 1 fixed to the spray box 1.
One end of the baffle plate 1 is pivotally attached to the spray box 1 so as to be rotatable outwardly of the spray box 1 about a rotary shaft 16 of 7. For example, here, this fixed plate 1
A turning hole 19 is formed in the baffle plate 2 by moving a handle 15 fixed to a rotating shaft 16.
Is rotated to the outside of the spray box 1, and the position of the baffle plate 2 is fixed by a fixing bolt 18 at an appropriate position.

In FIG. 5, such a baffle plate 2 is provided on the left side of the spray box 1 on the front side A of the steel strip 3 and on the right side of the spray box 1 on the rear side B of the steel strip 3. The difference is provided. When a fluttering or twist phenomenon occurs, the pair of baffle plates 2 which are provided at the wrong end are respectively rotated to discharge the refrigerant from the gap portion of the spray box 1 near the edge portion, that is, the spray box 1. The opening width is adjusted. As a result, at the edges of the steel strip 3, the front and back sides of the steel strip 3 A, B
A change occurs in the exhaust flow of the refrigerant.

That is, when the baffle plate 2 is fixed at an angle as shown in FIG. 5, the exhaust flow of the refrigerant is once blocked by the baffle plate 2 at the left side edge portion of the front side A and the right side edge portion of the back side B. After being stopped, the baffle plate 2 flows out of the blowing box 1, but at the right side edge portion of the front surface side A and the left side edge portion of the back surface side B where the baffle plate 2 is open to the outside of the blowing box 1, the exhaust flow of the refrigerant is Since it is not limited, it flows out of the spray box 1 as it is. The front side A and the back side B at the edge portion of the steel strip 3 generated by this
A bending moment 14 is generated in the steel strip 3 due to the pressure difference, and the steel strip 3 stands still in the state as shown in FIG. 7, for example.
This stationary angle naturally changes depending on the bending rigidity of the steel strip 3.

Even in the case of this rotary type baffle plate, like the slide type baffle plate, it may be installed on the right side of the front side A and the left side of the rear side B without permission. Of the pair of spray boxes 1 facing each other as shown in FIG. 1, they may be installed at both ends of one spray box 1. In FIG. 8, a pair of baffle plates 2 are axially attached to the back surface side B of the steel strip 3, but in this case, the steel strip back surface B
At the left and right edge parts of the refrigerant, the exhaust gas flow of the refrigerant is blocked by the baffle plate 2 at one end and then flows out of the spray box 1, while the baffle plate 2 is exposed to the outside of the spray box 1 on the surface side A. At the left and right edge portions, the exhaust flow of the refrigerant is not limited, and therefore flows out of the spray box 1 as it is.

A bending moment 14 is generated in the steel strip 3 due to the pressure difference between the front surface side A and the back surface side B at the edge portion of the steel strip 3 generated in this way. In this case, the steel strip 3 is as shown in FIG. Both edges of the steel strip 3 are slightly closer to the surface side A, C
It stands still in a warped state. Naturally, the amount of C warp varies depending on the bending rigidity of the steel strip 3. In FIG. 8, the baffle plates 2 are attached to both sides of the back side B spraying box 1, but they may of course be attached to both sides of the front side A spraying box 1.

By providing the slide type or rotating type baffle plate 2 and adjusting the distance of the gap portion near the edge portion in this way, a pressure difference occurs between the front surface side A and the back surface side B of the steel strip 3. As a result, a bending moment 14 is generated, and the steel strip 3 balances and stands still, so that it is possible to stop the fluttering and the twist phenomenon that have occurred at the edge portion of the steel strip 3. Therefore, it is possible to prevent the contact between the steel strip 3 and the spray box 1, and it is possible to improve the product quality by eliminating the damage to the steel strip 3 which has occurred conventionally. In addition, it is not necessary to reduce the line deceleration, the flow rate of the refrigerant sprayed, and the distance between the steel strip 3 and the spray box 1 longer than in the conventional case, so that the productivity can be improved. Also, in hot dipping equipment,
When the present invention is applied to cooling after plating, the distance between the wiping nozzle for plating and the steel strip 3 does not change, so the precision of the coating weight is improved.

In the present embodiment, the cooling apparatus for cooling the steel strip has been described as an example. However, for example, in the preheating zone on the inlet side of the continuous annealing equipment, the heating medium is sprayed onto the steel strip to preheat the steel strip. The present invention can also be applied to a heating (preheating) device to be performed or a drying device for drying a steel strip by spraying a heat medium onto the steel strip in a chromic acid treatment after plating. The structure of the spraying device and the baffle plate in that case is the same as that of the cooling device mentioned above, and the effect obtained by the structure is also the same.

In this embodiment, the case where the cooling device is applied to the vertical furnace has been described, but the present invention can of course be applied to a horizontal cooling device. In that case, FIGS. 2, 3, 4, 5, 7, and 8 should be viewed as a vertical cross section of the horizontal cooling device. That is, also in the case of a horizontal furnace, the baffle plates 2 are installed on both left and right edge portions of the front side surface A of the steel strip 3 of the spray box 1 as in the case of the vertical embodiment.
Or, baffle plates are installed on both left and right edges of the back side B of the steel strip 3 of the spray box 1, or installed on the left edge of the front side A and the right edge of the back side B of the steel strip 3 of the spray box 1. Alternatively, it may be installed on the right edge portion on the front surface side A or the left edge portion on the back surface side B of the steel strip of the spray box 1.

The point is that by appropriately adjusting the gaps in the vicinity of both edges of the spray box 1, the flow of the refrigerant on the front and back surfaces of the edge of the steel strip 3 is changed, and the surface of the steel strip at the edge of the steel strip 3 is changed. By generating a pressure difference on the back surface, a rotational moment 14 is generated to balance the steel strip 3 in a constant state.
The purpose of the present invention is to make the steel strip 3 stand still, thereby eliminating the fluttering and the twist phenomenon, and allowing the steel strip 3 to pass through stably.

The baffle plate 2 is of a slide type that is movable in the vertical direction with respect to the facing surface of the spraying box 1 that is arranged to face it, or a rotary type that is rotatable toward the outside of the spraying box 1. Therefore, if fluttering or twisting occurs due to changes in plate conditions, the baffle plate position setting can be changed immediately according to the plate conditions to adjust the gap portion near the edge of the steel strip 13. By doing so, it is possible to prevent fluttering and twist phenomenon.

[0029]

According to the present invention, a refrigerant or heat medium is sprayed onto a steel strip from a spray box arranged on the front and back sides of the strip.
In a device for cooling, heating, or drying a steel strip, a pair of baffle plates for appropriately adjusting only the gaps of the spraying box arranged opposite to each other, particularly the gaps near the left and right edges of the steel strip are installed in the spraying box. By adjusting the gap portion by the baffle plate, the flow of the refrigerant or heat medium on the front and back surfaces of the steel strip is changed, and a pressure difference is generated between the front and back surfaces of the steel strip at the steel strip edge portion. As a result, a rotation moment is generated in the steel strip, and the steel strip is well balanced at a certain position and maintains a stationary state, thereby preventing the occurrence of fluttering, twist, etc., which was caused by the defective shape of the conventional plate. You can Therefore, the steel strip can be constantly passed through the steel strip, the steel strip does not come into contact with the spray box, the occurrence of scratches on the steel strip can be prevented, and the product quality can be improved.

Further, in order to prevent the fluttering and the twist phenomenon as in the conventional case, it is not necessary to reduce the line speed or reduce the amount of the blowing air of the refrigerant or the heat medium to the steel strip, so that the productivity is improved. be able to. Also,
In order to generate a pressure difference at the front and back edge portions of the steel strip as in the present invention and to generate a bending moment in the steel strip, it is also possible to change the amount of the refrigerant or heat medium sprayed at the edge portion itself, for example. However, in the present application, it is not necessary to have a complicated piping configuration for performing such air volume control,
A bending moment can be generated by a simple device configuration in which a baffle plate is attached to the blowing box and the gap portion near the steel strip edge portion is appropriately adjusted by the baffle plate.

Further, the baffle plate is a slide type which is movable in the direction perpendicular to the facing surface of the spray box placed opposite to the baffle plate, or one end of which is axially attached to the spray box so as to face the outside of the spray box. Since it is a rotating type that can be freely rotated, even if the passage of the steel strip becomes unstable due to changes in the strip conditions, the position of this baffle plate can be adjusted immediately to adjust the vicinity of the steel strip edge. It is possible to pass the steel plate in a stable manner by adjusting the gap portion.

[Brief description of drawings]

FIG. 1 is an overall view showing a cooling device for vertical continuous annealing equipment,

2 is a cross-sectional view of a spray box of the cooling device of FIG. 1,

FIG. 3 is a plan view of a spraying box in which slide type baffle plates are provided in oppositely arranged spraying boxes,

FIG. 4 is a plan view of a spray box in which slide type baffle plates are provided on both side surfaces of one spray box that is arranged opposite to each other.

FIG. 5 is a cross-sectional view of a rotating baffle plate spray box,

FIG. 6 is a side view of a rotating baffle plate spray box.

FIG. 7 is a plan view of the spray box in which the rotatable baffle plate is provided in the spray box oppositely arranged, without permission.

FIG. 8 is a plan view of the spray box in which the rotatable baffle plates are provided on both side surfaces of one spray box that is arranged to face each other;

FIG. 9 is a perspective view showing a conventional cooling device,

FIG. 10 is a perspective view showing a conventional cooling device.

[Explanation of symbols]

1 spray box 2 baffle plate 3 steel strip 4 Blower 5 nozzle holes 6 gap 7 Conveyor roll 8 ducts 9 heat exchanger 10 Suction mouth 11 furnace body 12 Y-shaped duct 13 Guide plate 14 Bending moment 15 handle 16 rotation axes 17 Fixed plate 18 Fixing bolt 19 Rotating hole A Steel strip front side B Steel strip back side

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keiji Ogushi             46-59, Nakahara, Tobata-ku, Kitakyushu, Fukuoka New             Nippon Steel Co., Ltd. Engineering Business             Department F-term (reference) 4K043 AA01 CA00 CB03 DA05 EA02

Claims (3)

[Claims] 1. A device for cooling or heating or drying a steel strip by spraying the refrigerant or the heat medium onto the steel strip from a spray box of the refrigerant or the heat medium arranged on the front and back sides of the steel strip so as to face each other,
The pair of baffle plates for appropriately adjusting only the gap portions in the vicinity of the left and right edge portions of the steel strip in the gap between the blowing boxes arranged to face each other are installed in the blowing box, and the gap portions are adjusted by the baffle plates, By changing the flow of the refrigerant or heat medium on the front and back surfaces of the steel strip, a pressure difference is generated between the front and back surfaces of the steel strip at the steel strip edge portion, and the steel strip is characterized by stable striping. Equipment for cooling, heating or drying. 2. A pair of baffle plates located near both left and right edge portions of the steel strip are slide types that are movable in the vertical direction with respect to the facing surfaces of the spray box that is disposed facing each other. An apparatus for cooling, heating or drying the steel strip according to claim 1. 3. A pair of baffle plates located near both left and right edge portions of the steel strip are pivotally attached at one end to a spray box and are rotatable toward the outside of the spray box. An apparatus for cooling, heating, or drying a steel strip according to claim 1.