KR101543883B1 - Hot Milled Strip Pickling Method and Device - Google Patents

Abstract

The present invention makes it possible to reduce the burden of logistics and space, as well as to eliminate the additional process and additional work due to the tertiary scale, including hot rolling; Cooling and descaling the cooling water to a strip with ice so as to cool and strip the strip having a temperature of 600 ° C or higher after passing through the hot rolling step; And a pickling step of passing the strip through an acid solution.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a hot rolling strip pickling method,

The present invention relates to a method for pickling a strip having been subjected to hot rolling and a hot rolling continuous pickling apparatus, and more particularly, to a pickling method and a pickling apparatus for pickling a hot strip at a high temperature without a separate slow cooling process.

As shown in FIG. 1, a hot rolled steel sheet produced at a hot rolling mill passes through a hot rolling 10, is cooled while passing through a runout table (ROT) 20, and is wound by a coiler 30. The coil thus wound is slowly cooled in the yard 40 and then unwound into the strip by the uncoiler 50 and picked up 60 by passing through the pickling tanks 61, 62, 63 and 64.

When the hot-rolled steel sheet having such a high temperature is wound by a coil to slowly cool it, it must be placed on the yard 40 for a long time. Placing it in the yard 40 for such a long time not only causes the coil to have a tertiary scale, Problems such as congestion occur. That is, the hot-rolled coil supplied to the pickling line is coiled at 500 ° C or higher in the hot rolling mill and cooled to room temperature before entering the cold-rolling pickling factory, and the cooling time is about 72 hours.

As shown in Patent Document 1, there has been proposed a method in which the temperature of the hot-rolled steel sheet is kept constant through uniform heating after coil / uncoiling, followed by cooling through a cooling spray, and then a pickling process is performed. A uniform heating device is required to reduce the temperature variation in the width direction of the hot-rolled coil caused by winding, and a non-oxidizing atmosphere device is required to prevent oxidation in the uniform heating, and a high temperature strip There is a problem that it is difficult to cool at an appropriate temperature (about 120 DEG C in Patent Document 1).

(Patent Document 1) JP2004-072842 A

The present invention relates to a hot rolling process capable of eliminating the burden of logistics and space as well as eliminating the additional process and the additional work due to the tertiary scale since the hot rolling process is not required in the pickling process after the conventional hot rolling process, And to provide a hot rolling continuous pickling facility.

The present invention also relates to a process for producing a hot rolled steel sheet, comprising the steps of removing a primary scale formed on a strip passed through hot rolling, cooling the strip to a temperature suitable for pickling, passing the hot rolled strip through hot rolling, A method for picking up a strip and a hot rolling continuous pickling facility.

The present invention provides a method for pickling a strip passed through hot rolling and a hot rolling continuous pickling apparatus for the following purpose.

The present invention relates to a hot rolling process, Cooling and descaling the cooling water to a strip with ice so as to cool and strip the strip having a temperature of 600 ° C or higher after passing through the hot rolling step; And a pickling step of passing the strip through an acid solution.

In the present invention, the cooling and descaling step may be performed such that the strip provided to the pickling step has a temperature of 100 to 200 ° C.

Also, in the present invention, the cooling and descaling step may spray cooling water of 300 bar or more at 500 l / min or more, and the ice may have a diameter of 1 mm or more.

Further, in the present invention, after the cooling and descaling step, it may include an additional cooling step in which the cooling water is secondarily cooled by passing through it.

Wherein the additional cooling step may be performed such that the strip passing through the additional cooling step between the pickling step and the cooling and descaling step has a temperature of 100-200 [deg.] C.

The present invention, on the other hand, relates to a cooling and descaling device arranged in series with a hot rolling device, comprising a spraying means for spraying ice and cooling water into strips to cool the strip and to remove scale; And a pickling device disposed at a rear end of the cooling and descaling device, the pickling device including an acid solution storage tank through which the strip passed through the cooling and descaling device passes.

In addition, in the present invention, the injection means is disposed on the upper and lower surfaces of the passing strip, and the upper and lower injection means are connected to different high-pressure forming portions, and the high-pressure forming portion can provide high-pressure cooling water.

In addition, the injection means may include a jetting portion formed with an opening for jetting ice and cooling water, a cooling water supply portion connected to the jetting portion and supplied with cooling water, A cooling water channel connecting the cooling water supply unit and the injection unit; And an ice supply part connected to the cooling water flow path and supplying ice to the cooling water flow path so that ice is mixed with the cooling water flow.

The injection means may further include a cross-sectional change portion located before the connection point between the cooling water passage and the ice supply portion and having a cross section of the cooling water passage that changes the speed of the cooling water supplied to the cooling water passage.

In the present invention, the hot rolling continuous pickling apparatus may include a coolant storage tank disposed between the acid solution storage tank and the cooling and descaling apparatus and storing cooling water for cooling the passing strip.

According to the present invention, it is possible to reduce the burden on the logistics and the space, and it is possible to provide a strip passing through the hot rolling, which can eliminate the additional process and the additional work due to the tertiary scale A pickling method and a hot rolling continuous pickling facility can be provided.

The present invention also relates to a process for producing a hot rolled steel sheet, comprising the steps of removing a primary scale formed on a strip passed through hot rolling, cooling the strip to a temperature suitable for pickling, passing the hot rolled strip through hot rolling, A method of picking the strip and a hot rolling continuous pickling facility can be provided.

1 is a conceptual view showing a pickling process of a conventional hot rolled strip.
2 is a conceptual view showing a pickling process of a hot rolled strip according to an embodiment of the present invention.
3 is a conceptual cross-sectional view illustrating one embodiment of the cooling and descaling apparatus of the present invention.
4 is a cross-sectional view showing the nozzle unit of the injection means of the present invention.
5 is a graph showing the degree of pickling with temperature.
6 is a conceptual view illustrating a pickling process of a hot rolled strip according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In the present invention, the latent heat of the hot-rolled strip is utilized, and the hot-rolled strip is pickled immediately without being cooled to room temperature. By doing so, not only is there no room for forming a tertiary scale which is relatively difficult to remove, but also high-temperature pickling is possible, which increases the pickling efficiency.

Further, the hot strip is cooled to a temperature suitable for pickling, and the primary scale formed on the hot strip is physically removed, thereby simplifying the process and may not require additional facilities.

FIG. 2 is a conceptual view illustrating a pickling process of a hot rolled strip according to an embodiment of the present invention. FIG. 3 shows an embodiment of the spraying device of the present invention. Sectional view showing a nozzle portion of the ink jet recording head.

2, the pickling process of the hot rolled strip according to an embodiment of the present invention is performed through the hot rolling 110 and the runout table 120, and after passing through the runout table 120, the temperature sensor 130 The temperature of the strip entering the cooling and descaling apparatus 140 is measured.

And then passes through the cooling and descaling device 140 where it first cools the primary scale formed on the strip surface while cooling the strip and passing through the hot rolling 110 and runout table 120. Thereafter, the strip passes through the cooling bath 150 to have a temperature of 100 to 200 DEG C which is the pickling temperature, and then passes through the pickling tanks 161, 162, and 163 sequentially for pickling 160. [ In the present invention, the hot rolling apparatus may include a run-out table (ROT) 120 as well as hot rolling 110.

As shown in FIG. 3, a cross-sectional view of the cooling and descaling apparatus 140 of the present invention is shown. The cooling and descaling apparatus 140 includes an outer frame 141 having an inlet and an outlet through which the strip passes, an upper nozzle 143 disposed at an upper portion of the strip within the outer frame 141, (142) for preventing the outflow of cooling water and ice sprayed to the upper nozzle (143) and the lower nozzle (144) and assisting the movement of the strip is provided to the cooling and descaling device 140 at the entrance and exit.

The upper and lower nozzles 143 and 144 are connected to a cooling water supply unit 146 for supplying cooling water and an ice supply unit 147 for supplying ice and connected to a mixing unit 145 for mixing ice with cooling water Upper nozzles 143 are connected to each other, and lower nozzles 144 are connected to lower nozzles.

4, the upper and lower nozzles 143 and 144 include a jetting portion 143a and a mixing portion 145 connected to the jetting portion 143a. The mixing portion 145 includes a cooling water supply portion 146, And an ice channel 148 connected to the ice channel 147 and the ice channel 147 are connected.

In this case, the mixing section 145 is provided with a cross section in which the cross section of the cooling water flow passage is changed so as to change the speed of the cooling water supplied to the cooling water flow passage 149 at a point before the cooling water flow passage 149 and the ice channel 148 are connected The changing portion 145a is formed. The cross-sectional changing portion 145a increases the speed of the cooling water before the cooling water and the ice are mixed, thereby facilitating the mixing of the ice into the cooling water.

In the present invention, the strip after passing through the hot rolling apparatuses 110 and 120 is subjected to the cooling and descaling apparatus 140 and the cooling tank 150 before picking the strip having a temperature of 600 ° C or higher , And the pickling (160) is performed at a temperature suitable for the latent heat of the strip passed through the hot rolling. By not cooling the strip to a normal temperature, it is not necessary to adjust the temperature of the strip for pickling.

Also, by performing physical descaling, such as a blaster, performed prior to the pickling 160 with cooling, the process can be simplified. Due to the latent heat of the strip, the high temperature pickling 160 is performed, which increases the efficiency of the pickling 160.

In this connection, FIG. 5 shows the degree of pickling according to the pickling temperature. The X axis in FIG. 5 means temperature, and the Y axis means picking time. As shown in Fig. 5, the higher the temperature of the pickling, the shorter the time required for pickling. That is, the pickling efficiency is increased.

In the present invention, part of the conventional pickling tanks 161 to 163 is filled with water instead of the acid solution, It can be utilized as the cooling bath 150. This can compensate for the cooling performance that may be lacking in simultaneously performing cooling and descaling of the high temperature strip. By immersing the strip in the cooling bath 150, the strip has a uniform temperature and is advantageous in cracking.

Further, in the present invention, since the hot hot strip is supplied by pickling, there is no need to provide a heating device for the acid tank for high temperature pickling. That is, since the high-temperature strip of 100 to 200 ° C is supplied to the acid tank, the acid solution is heated up during the pickling, and even if there is no separate heating device, the high-temperature pickling can naturally be performed. In addition, by providing a high-temperature strip at a temperature of 100 to 200 ° C as an acid tank, high-temperature pickling can be performed, thereby increasing the pickling efficiency and preventing excessive evaporation of the acid.

In the present invention, the cooling and descaling apparatus 140, together with the water for cooling, ejects ice for scaling to the surface of the strip, and removes the scale formed on the surface of the strip by physical blowing of the solid ice. At this time, after the ice is hit by striking the surface of the strip, the temperature of the strip immediately changes to water due to the temperature of the strip, so ice for scaling off the strip can also be used for cooling down the temperature of the strip.

In addition, in the case of the cooling and descaling apparatus 140 of the present invention, the ice is melted so that the water can be separated from the water by the water It can be processed together with the cooling water, so that a separate re-circulating water system is not required, and the trouble such as clogging of the pipe may not be caused.

At this time, cooling water of 300 bar or more is sprayed at 500 l / min or more in the cooling and descaling apparatus 140, and the diameter of the ice to be introduced is preferably 1 mm or more, , To remove scale due to ice. That is, when the diameter of the inserted ice is less than 1 mm, the impact due to ice is not large and the scale is not braked, so that the diameter of the ice to be introduced is preferably 1 mm or more.

6 shows another embodiment of the present invention.

6, the pickling process of the hot-rolled strip according to another embodiment of the present invention passes through the hot-rolling 210 and the run-out table 220, passes through the run-out table 220, . Thereafter, without moving through a yard or separate cooling device, the location is shifted and unwrapped by the uncoiler 226 to a strip, and then the temperature of the strip entering the cooling and descaling device 240 through the temperature sensor 230 Is measured.

Then passes through the cooling and descaling device 240 where it cools the strip and passes through the hot rolling 210, the run-out table 220 and the coils and uncoilers 225 and 226, Remove the scale first. Thereafter, the strip has a pickling temperature of 100 to 200 DEG C, and then passes through the pickling tanks 261, 262, 263, and 264 sequentially for pickling 260. [

In the case of the embodiment of Fig. 6, due to space constraints, the strip is moved through the coil / uncoil when the installation is not directly connected. Thus, there is no additional process between the coil and the uncoil, such as a chill for cooling, and therefore no additional logistical costs may be added. In addition, it has the advantage of being able to reduce the initial cost in that it can utilize existing facilities.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

110: hot rolling 120: runout table
130: Temperature sensor 140: Cooling and descaling device
141: outer frame 142: roll
143: upper nozzle 144: lower nozzle
145: mixing section 146: cooling water supply section
147: ice supplier 148: ice euro
149: cooling water flow path
150: cooling tank 161 to 163: acid tank

Claims (11)

A hot rolling step;
A cooling and descaling step of ejecting cooling water into the strip together with ice so as to cool and strip the strip passing through the hot rolling step;
A pickling step of passing the strip through an acid solution; And
And after the cooling and descaling step, an additional cooling step in which the cooling is secondary cooled by passing cooling water.
The method according to claim 1,
The strip immediately after passing through the hot rolling step has a temperature of 600 ° C or higher,
Wherein the cooling and descaling step is performed such that the strip provided to the pickling step has a temperature of 100-200 ° C.
3. The method of claim 2,
Wherein the cooling and descaling step is performed by spraying cooling water of 300 bar or more at 500 l / min or more.
4. The method according to any one of claims 1 to 3,
Wherein the ice has a diameter of 1 mm or more.
delete The method according to claim 1,
Wherein the additional cooling step is performed such that the strip passed through the additional cooling step between the pickling step and the cooling and descaling step has a temperature of 100-200 占 폚.
A cooling and descaling device disposed in series with the hot rolling device and including ejecting means for ejecting ice and cooling water into the strip to cool the strip and remove scale;
A pickling device disposed at a rear end of the cooling and descaling device and including an acid solution storage tank through which the strip passed through the cooling and descaling device passes; And
And a cooling water storage tank disposed between the acid solution storage tank and the cooling and descaling apparatus, the cooling water storing cooling water cooling the strip passing therethrough.
8. The method of claim 7,
Wherein the spraying means is disposed on the upper and lower surfaces of the passing strip, the upper and lower spraying means are connected to different high-pressure forming portions, and the high-pressure forming portion provides high-pressure cooling water.
8. The method of claim 7,
The injection means
A spraying portion having an opening for spraying ice and cooling water;
A cooling water supply unit connected to the jetting unit and supplied with cooling water;
A cooling water channel connecting the cooling water supply unit and the injection unit;
And an ice supplying unit connected to the cooling water channel and supplying ice to the cooling water channel so that ice is mixed with the cooling water flow.
10. The method of claim 9,
Wherein the injection means further includes a cross-section changing portion which is positioned before a connecting point between the cooling water passage and the ice supplying portion and whose cross section of the cooling water passage is changed so as to change the speed of the cooling water supplied to the cooling water passage. Continuous pickling equipment.
delete

Images