KR101353547B1 - Cooling device of continuous galvanizing line - Google Patents

Abstract

Plating bath to increase the cooling efficiency of the steel plate, minimize the cooling variation in the entire area of the steel plate surface, and to inject and hot-plate the steel sheet to maintain the overall blowing pressure of the cooling air blown to the steel plate surface And an air knife for controlling the coating amount on the surface of the steel sheet passing through the plating bath, and a cooling device for cooling the steel sheet by an alloying treatment for reheating the steel sheet, wherein the cooling device is provided on both sides of the steel sheet in the width direction. It is disposed between the plurality of injection pipes for injecting the cooling medium on the surface of the steel plate, and are arranged at intervals along the moving direction of the steel plate, the blower connected to the injection pipe for supplying a cooling medium, is installed between the injection pipes Cooling station of a hot-dip galvanizing facility including a discharge portion which is ejected from the injection pipe and exits the cooling medium heat exchanged with the surface of the steel sheet It provides.

Description

Cooling device of hot dip galvanizing facility {COOLING DEVICE OF CONTINUOUS GALVANIZING LINE}

The present invention relates to a facility for continuously plating molten metal. More particularly, the present invention relates to a chiller in a hot dip galvanizing installation for cold treating an alloy heat treated hot dip galvanized steel sheet.

In general, galvanized steel sheet is classified into hot dipped galvanized steel (Iron) and galvanized steel sheet (galvanized steel sheet). The demand is increasing as steel sheets for home appliances and automobiles.

An alloyed hot dip galvanized steel sheet is usually manufactured through an alloying heat treatment step of continuously heating a plated steel sheet in a continuous hot dip galvanizing line to a temperature range of 470 to 560 ° C. As a result, the iron component of the base iron and the zinc component of the plating layer were diffused to each other to grow Fe-Zn-based intermetallic compounds such as zeta (ζ), delta (δ ₁ ), gamma (γ), and the like. Is formed.

Although the quality characteristics of the alloyed hot-dip galvanized steel sheet is very excellent, the superalloyed steel sheet in the alloying process has a problem in that the powdering (falling) of the plating layer in the form of powder during processing occurs.

Powdering deteriorates proportionately with the increase of iron concentration of iron alloy, but the adhesion and weldability are reversely improved, so considering the characteristics, the optimum iron concentration range of the plating layer of alloyed hot-dip galvanized steel sheet is relatively narrow, about 8-12%. It is common to have a delta (δ ₁ ) phase as the main phase.

For this purpose, the cooling control technology after alloying heat treatment is very important in the manufacture of alloyed hot-dip galvanized steel sheet. That is, after the alloying heat treatment, if the plated steel sheet is not cooled to about 350 ° C. or lower when it reaches the top roll of the cooling stand, the adhesion of the zinc particles in the plating layer may not be complete, and zinc particles may fall on the top roll due to friction with the top roll. Sticks. Particles fixed to the upper roll causes a flaw on the surface of the steel sheet, or the alloying proceeds under the influence of latent heat of the material to develop into superalloy, thereby creating a structure vulnerable to workability. As a result, a powdering phenomenon in which the plating layer falls off in powder form during processing is required, so proper cooling control is required.

Accordingly, during the manufacture of alloyed hot-dip galvanized steel sheet, the cold-rolled steel sheet is continuously alloyed to secure an appropriate degree of alloying, and then cooled by air cooling or water mist.

In the conventional air cooling structure, cooling air is injected to the steel plate surface through a nozzle to cool the steel plate surface, and the heated air discharges the left and right sides.

However, the above-described conventional structure stays as the cooling air heated by hitting the steel sheet is discharged to the left and right sides of the steel sheet, thereby decreasing the cooling efficiency. In addition, there is a problem that a deviation occurs in the heat treatment temperature in the central portion and both side portions of the steel sheet. In addition, the conventional structure has a problem that it is difficult to uniform alloying by the shaking of the steel sheet due to the air pressure during the air blowing and generating a high stagnation pressure on the surface of the steel sheet.

In this way, the deviation of the heat treatment temperature occurs in the alloying, and when the steel sheet is thick or the steel plate is running fast, the cooling effect is insufficient and the steel sheet temperature at the upper roll does not reach the proper temperature, resulting in over alloying or powdering. Problems arise.

Accordingly, the present invention provides a cooling apparatus of a hot dip galvanizing facility, which can increase the cooling efficiency of a steel sheet.

In addition, the present invention provides a cooling apparatus of a hot dip galvanizing installation, which is capable of minimizing cooling variation in the entire area of the steel plate surface.

In addition, the present invention provides a cooling apparatus of a hot dip galvanizing installation, which is capable of maintaining a uniform blowing pressure of cooling air blown onto a steel plate surface.

To this end, the apparatus includes a plating bath for drawing and melting a steel sheet, an air knife for controlling the amount of plating on the surface of the steel sheet passing through the plating bath, and an alloying treatment for reheating the steel sheet, thereby cooling the steel sheet. The cooling apparatus includes a plurality of spray pipes disposed in the width direction on both sides of the steel sheet and spaced along the moving direction of the steel sheet to inject cooling medium onto the surface of the steel sheet, and connected to the spray pipes to form a cooling medium. It may include a blower for supplying the discharge portion is installed between the injection pipe is injected from the injection pipe exiting the cooling medium heat exchanged with the surface of the steel sheet.

The discharge part may be installed in the width direction of the steel plate between the injection pipe and may include at least one suction duct having a suction port through which a cooling medium flows.

The discharge part may further include a suction pump connected to the suction duct to suction and discharge the cooling medium.

In addition, the injection pipe is formed with injection slits in which a cooling medium is injected along the longitudinal direction, and the injection slits may have a structure in which the width decreases toward both ends from the center.

On the other hand, the present apparatus is a cooling bath for cooling a steel plate by a plating bath for drawing and melting the steel plate, an air knife for controlling the amount of plating on the surface of the steel plate passing through the plating bath, and an alloying treatment for reheating the steel plate. The cooling apparatus includes a plurality of spray pipes disposed in the width direction on both sides of the steel sheet and spaced along the moving direction of the steel sheet to inject cooling medium onto the surface of the steel sheet, and connected to the spray pipes to form a cooling medium. It includes a blower for supplying, the injection pipe is formed with a spraying slit for the cooling medium is injected along the longitudinal direction, the spraying slit may have a structure that the width becomes smaller toward both ends from the center.

According to this embodiment as described above, the cooling medium injected into the steel sheet is not only escaped through the injection pipe but also between the injection direction of the steel sheet, it is possible to discharge the hot cooling medium more quickly. As a result, it is possible to prevent the decrease in cooling efficiency caused by the warming of the cooling medium in the cooling zone and to cool the steel sheet more quickly and effectively.

In addition, it is possible to smoothly discharge the cooling medium to minimize the shaking of the steel sheet due to the air pressure inside the cooling table and to maintain a uniform blowing pressure on the steel sheet to improve the quality of the product.

In addition, by varying the injection amount of the cooling medium in accordance with the temperature distribution of the steel sheet, it is possible to cool the steel sheet as a whole. Thus, minimizing the cooling deviation of the surface of the steel sheet to prevent over alloying, increase the powder resistance, and enables uniform alloying.

1 is a schematic diagram showing a hot dip galvanizing installation having a cooling apparatus according to the present embodiment.
2 is a perspective view showing a part of a configuration of a cooling apparatus of a hot dip galvanizing installation according to the present embodiment.
3 is a schematic view showing the jet slit structure of the cooling apparatus according to the present embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art can easily understand, the embodiments described below may be modified in various forms without departing from the concept and scope of the invention, and the embodiments described herein. It is not limited to the example.

The drawings are schematic and illustrate that they are not drawn to scale. The relative dimensions and ratios of the parts in the figures are shown exaggerated or reduced in size for clarity and convenience in the figures, and any dimensions are merely illustrative and not restrictive.

1 shows a hot dip galvanizing installation with a cooling device according to the present embodiment.

Looking at the hot dip galvanizing facility with reference to Figure 1, the facility is a plating bath 100 for the hot-plated hot-plate (P) and the plating bath 100 is located on the plating bath 100 and plated on the surface of the steel sheet (P) The air knife 110 for controlling the deposition amount, the alloying treatment furnace 120 is disposed in the rear end of the air knife 110 along the movement path of the steel plate (P) to heat the steel plate (P), the alloying treatment furnace (120) Located at the rear end and comprises a cooling device 10 for cooling the steel sheet (P).

Thus, the steel sheet (P) is guided to the plating bath 100 through the snout 102, and then the progression direction is changed by the sink roll 104 to proceed vertically upward while the plating process is performed. The plated steel sheet P whose surface is plated by the molten metal in the plating bath 100 is withdrawn from the plating bath 100, and then the plating amount is controlled by the air knife 110. The plated steel sheet P in a state in which the plating amount is controlled is heated in the range of 470 to 560 ° C. while passing through the alloying furnace 120 and alloyed. The alloyed steel sheet P is cooled to an appropriate temperature while passing through the cooling device 10 disposed at the rear end of the alloying furnace 120 and manufactured as an alloyed hot dip galvanized steel sheet P. The steel sheet P passing through the cooling device 10 is turned over past the upper roll 130 and proceeds to a later process.

In the present embodiment, the cooling device 10 is disposed on both sides of the steel plate (P) in the width direction and are installed at intervals along the moving direction of the steel plate (P) to a plurality of injection pipes for spraying the cooling medium on the surface of the steel sheet (P) ( 20), a blower connected to the injection pipe 20 to supply a cooling medium, and a cooling medium installed between the injection pipes 20 and sprayed from the injection pipe 20 to exchange heat with the surface of the steel sheet P. It includes a discharge exit.

Here, the device may be applied to various gases as the cooling medium is not particularly limited. In the present embodiment, a structure using air as a cooling medium will be described as an example.

In this device, the cooling air injected from the injection pipe 20 to the steel sheet P is heat-exchanged with the steel sheet P, and then flows out in the width direction of the steel sheet P, as well as exits through the discharge portion, so that the discharge is more smooth. This is done. Therefore, the cooling air heat-exchanged with the steel sheet P is discharged more quickly, so that the cooling efficiency of the steel sheet P can be increased.

As shown in Figure 2, the injection pipe 20 is disposed opposite to both sides of the steel sheet (P). The injection pipe 20 extends in the width direction of the steel plate P, and an injection slit 22 for injecting cooling air toward the steel plate P is formed. The plurality of injection pipes 20 are arranged at intervals along the advancing direction of the steel sheet P to form a cooling table 12.

The injection slit 22 extends along the injection pipe 20 and has a very narrow structure. The cooling air introduced into the injection pipe 20 is in the width direction of the steel sheet P through the injection slit 22. Sprayed into the whole. The structure of the injection slit 22 will be described later.

The blower is for high pressure blowing the cooling air to the injection pipe 20, the supply line 24 is connected to each injection pipe 20, and the blowing fan 26 is provided on the supply line 24 ).

Accordingly, when the blower fan 26 is driven, cooling air is supplied to the respective injection pipes 20 through the supply line 24 and sprayed to the surface of the steel sheet P through the injection slits 22 formed in the injection pipe 20. .

In the present embodiment, the discharge portion is installed in the width direction of the steel plate (P) between the injection pipe 20 disposed on both sides of the steel sheet (P) at least one or more suction in which the heated air flowing through the steel sheet (P) is introduced And a suction pump 34 connected to the duct 30 and the suction duct 30 to suction and discharge the cooling medium.

The suction duct 30 is installed between the injection pipe 20 and the injection pipe 20 and has a structure in which a plurality of suction ducts are arranged at intervals along the traveling direction of the steel sheet P in the cooling table 12. . In addition, the suction duct 30 extends in the width direction of the steel sheet P, and the suction port 32 is formed on the front surface thereof so that the heated air can be sucked through the steel sheet P. The size of the suction port 32 or the suction amount through the suction port 32 may vary depending on the injection amount of the cooling air through the injection pipe 20 and may be variously changed.

Each of the suction ducts 30 is connected to each other via a common duct 36 to communicate with each other, and the suction ducts 34 are installed in the common duct 36. Accordingly, when the suction pump 34 is driven, suction pressure is applied to each suction duct 30 connected to the common duct 36, and the air in the cooling table 12 is sucked through the suction port 32 in front of the suction duct. do.

Therefore, through the suction pressure applied to the suction duct 30, it is possible to quickly discharge the heated air remaining in the cooling table 12 to the outside.

In this way, the cooling air injected from the injection pipe 20 to the steel plate P is heated by heat exchange with the steel plate P, and the heated air is heated at both sides in the width direction of the steel plate P as well as the suction port of the suction duct 30. (32) Exit quickly through three directions. Therefore, the cooling efficiency is increased, and in particular, as the hot air stagnated at the center portion of the steel sheet P is rapidly discharged through the inlet 32, the central portion of the steel sheet P has a lower cooling effect than the edge. Prevent and uniform cooling.

In addition, the suction duct 30 is further disposed between the injection pipe 20 and the injection pipe 20 to further buffer the air pressure of the cooling air ejected from the injection pipe 20. That is, the cooling air is injected at a high pressure through the injection slit 22 of the injection pipe 20 to impact the surface of the steel sheet (P). In this process, the cooling air injected at a high pressure is rapidly discharged through the suction duct 30 to reduce the impact applied to the steel sheet P, and the pressure of the entire cooling table 12 becomes uniform.

Meanwhile, as shown in FIG. 3, the apparatus has a structure in which the width of the jet slit 22 formed in the jet tube 20 decreases from the center to both ends. Accordingly, the injection amount of the cooling air injected through the injection slits 22 is varied along the width direction of the steel sheet P.

The steel plate P has a temperature of about 20 to 30 ° C. higher in the center than both edges along the width direction. This apparatus can minimize the cooling temperature variation of the central portion and the edge by varying the injection amount of the cooling air injected to the steel sheet (P) along the width direction of the steel sheet (P) as described above.

Here, the injection slit 22 is formed so that both ends are symmetrically formed around the center, and the width d1 of the center is widest and the width d2 of both ends is narrowest.

In the present embodiment, the width of the injection slit 22 gradually decreases from the center to both ends, but the width decreases gradually, regardless of whether the variation is linear or quadratic. Means.

As described above, as the injection slit 22 decreases in width from the center of the injection tube 20 to both side ends, the amount of cooling air injection increases from both side ends to the center part. The difference in width between the center portion and both side ends of the injection slit 22 can be variously set according to the injection conditions of the cooling air, the steel plate P width direction difference, and the like, and is not particularly limited.

Thus, by increasing the injection amount of the cooling air injected through the injection slit 22 at the center portion of the steel sheet (P) it is possible to reduce the temperature deviation at the edge and the center portion of the steel sheet (P).

[Example]

The hot-dip galvanizing was performed by moving the cold-rolled steel sheet P having a material thickness of 1.0 mm and a width of 1,200 mm at an operating speed of 120 mpm. The plating deposition amount of the steel sheet P was determined by detecting the temperature of the steel sheet P past the cooling stand 12 for the thin plated steel sheet P having a thickness of 45 to 60 g / m 3 on one side.

As a result of the experiment under the same conditions, it was confirmed that the temperature of the steel sheet P was lowered by about 40 ° C. in the case of the equipment having the cooling device of the present embodiment compared with the equipment having the cooling device of the conventional structure. In addition, the temperature difference between the center portion and the edge of the steel sheet (P) was 20 ℃ or more difference in the conventional structure, but in the case of the present device was confirmed that the temperature distribution was more uniform 10 ℃ or less.

Thus, through this apparatus, it is possible to increase the cooling capacity of the steel sheet (P) and to uniformize the temperature distribution of the steel sheet (P).

While the illustrative embodiments of the present invention have been shown and described, various modifications and alternative embodiments may be made by those skilled in the art. Such variations and other embodiments will be considered and included in the appended claims, all without departing from the true spirit and scope of the invention.

10: cooling device 12: cooling table
20: injection pipe 22: injection slit
24: supply line 26: blowing fan
30: suction duct 32: suction port
34: suction pump 36: common duct

Claims (5)

A subsequent stage of the alloying treatment of the hot-dip galvanizing facility comprising a plating bath for drawing the steel sheet into the hot dip plating bath, an air knife for controlling the amount of plating on the surface of the steel sheet passing through the plating bath, and an alloying furnace for reheating the steel sheet. In the cooling apparatus of the hot-dip galvanizing equipment for cooling the steel sheet located at
The cooling apparatus is disposed on both sides of the steel sheet in the width direction and is provided at intervals along the moving direction of the steel sheet to supply a plurality of spray tubes for spraying a cooling medium on the surface of the steel sheet, and to supply the cooling medium connected to the spray tubes. A discharge portion which is installed between the injection pipes and is discharged from the injection pipes and exits the cooling medium heat-exchanged with the surface of the steel sheet,
The injection pipe is formed with a jet slit for the cooling medium is injected, the jet slit has a structure that becomes smaller in width from the center to both ends along the width direction of the steel sheet,
The discharge unit is disposed in the width direction of the steel plate between the injection pipe and the injection pipe, the cooling device of the hot-dip galvanizing installation comprises a plurality of suction ducts formed inlet inlet for cooling medium flows in the front end facing the steel plate. delete The method of claim 1,
The discharge unit is connected to the suction duct further comprises a suction pump for sucking and discharging the cooling medium. delete delete

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