JP5794105B2 - Steel plate manufacturing equipment and manufacturing method - Google Patents

Description

  The present invention relates to the manufacture of steel sheets, such as the manufacture of cold-rolled steel sheets, and relates to a manufacturing facility and a manufacturing method for suppressing deterioration in the quality of steel sheets.

  In the manufacturing process of a cold-rolled steel sheet (which may be described as “cold-rolled steel sheet” in the following description), for example, as shown in FIG. The cleaning process of the rolling oil adhering to the surface of the steel strip C and the water removal process of removing the water adhering to the surface of the steel strip C are performed. In addition, FIG. 3 is a figure which shows schematic structure of the steel plate manufacturing equipment of a prior art example.

The water removal step is a step performed after the cleaning step, and is a step of performing a draining operation by the ringer roll 2 and a drying operation using the dryer 4 on the surface of the steel strip C.
However, in the steel sheet manufacturing facility 1 configured as shown in FIG. 3, when manufacturing a high-strength cold-rolled steel sheet (Si steel sheet) containing Si (silicon) element and cooled using a gas jet (GJ), The draining work is not sufficiently performed in the ringer roll 2, and there is a possibility that moisture remains locally on the surface of the steel strip C.

The water locally remaining on the surface of the steel strip C evaporates until it is dried by the dryer 4, but when the water remaining on the surface of the steel strip C evaporates, for example, FIG. As shown in FIG. 4, local electrochemical corrosion of Si represented by the reaction formula: Si + O ₂ → SiO ₂ occurs. As a result, Si oxide is locally generated on the surface of the steel strip C. In addition, FIG. 4 is a figure which shows the production | generation of Si oxide in the surface of a steel strip.

  When the steel strip C in which Si oxide is locally generated on the surface is annealed in the continuous annealing furnace 22 (annealing process), the locally generated Si oxide on the surface of the steel strip C is not reduced. , Si is concentrated, and the color tone of the surface of the steel strip C is locally black. For this reason, a linear pattern defect will be formed in the surface of the steel strip C, and there exists a possibility that the problem that the surface external appearance of the steel strip C may deteriorate may generate | occur | produce.

The state where moisture remains locally on the surface of the steel strip C occurs, for example, in the following situation.
In the situation where water is continuously removed using the ringer roll 2 for the steel strip C that is continuously conveyed, wear occurs in the portion of the ringer roll 2 that presses the edge portion of the steel strip C. There is a case.

When wear occurs in the portion of the ringer roll 2 that presses the edge portion of the steel strip C, a gap is formed between the surface of the steel strip C and the ringer roll 2, and therefore exists on the surface of the steel strip C. It is difficult to completely remove the moisture that is present.
Therefore, moisture remains locally on the surface of the steel strip C that has passed through the ringer roll 2 where wear has occurred.

  Moreover, when the steel strip C is dried together with moisture by the hot air blown by the dryer 4 in order to remove the water remaining locally, the temperature of the steel strip C rises by the hot air. For this reason, before the moisture is removed from the surface of the steel strip C, the remaining moisture contacts the air during evaporation in the local portion of the surface of the steel strip C where moisture remains. By doing so, corrosion will occur.

  Corrosion that occurs on the surface of the steel strip C is, for example, when the steel strip C is formed using Si steel, and local electrochemical corrosion of Si occurs. As a specific example, the composition of the steel strip C is mass%, C: 0.075 to 0.101 [%], Si: 0.20 to 0.56 [%], Mn: 1.50. 1.86 [%], P: 0.036 [%] or less, S: 0.004 [%] or less, and the remainder corresponds to the composition of Fe and inevitable impurities.

For this problem, for example, techniques described in Patent Document 1 and Patent Document 2 have been proposed.
In Patent Document 1, on the upstream side of a water cooling tank provided on the exit side of the continuous annealing furnace, on the exit side of the continuous annealing furnace, water cooling equipment provided with a liquid injection device for injecting cooling water onto the surface of the steel strip A cleaning facility is disclosed in which a liquid ejecting apparatus that ejects a cleaning liquid onto the surface of a steel strip is provided on the upstream side of the provided cleaning tank.

  In Patent Document 1, when water cooling or cleaning of the steel strip is performed on the exit side of the continuous annealing furnace, the steel strip temperature is set to 40 ° C. or less within 1 second from the start of water cooling or cleaning. Even in a thick steel strip, it is intended to suppress the occurrence of local stains (pattern defects) on the surface of the steel strip in the water cooling facility or cleaning facility on the exit side of the continuous annealing furnace.

On the other hand, in Patent Document 2, when a steel strip is cooled on the exit side of a continuous annealing furnace in a cleaning facility or a cooling facility, a cooling water having a water temperature of 30 [° C.] or lower is used in the air before immersion. A method of cooling by direct contact with the strip is disclosed.
Specifically, in Patent Document 2, a mist-like (average particle size of 50 [μm] or less) cooling water is placed locally on the upstream side of the cleaning equipment by placing equipment that directly contacts the steel strip in the air. The purpose is to reduce the temperature of the steel strip without causing any significant corrosion and to reduce the progress of corrosion of the steel strip and cooling water.

Japanese Patent Laid-Open No. 2005-200755 JP 2007-246990 A

In the techniques described in Patent Documents 1 and 2 described above, local corrosion of Fe (2Fe + O ₂ → 2FeO) generated on the surface of the steel strip when water cooling or cleaning is performed on the outlet side of the continuous annealing furnace. The purpose is to suppress.
However, on the exit side of the continuous annealing furnace, since the surface reduction reaction of the surface of the steel strip is completed by the annealing process, local corrosion of Si on the surface of the steel strip does not occur.

For this reason, even if local corrosion of Fe occurs on the surface of the steel strip on the entry side of the continuous annealing furnace, Si oxide can be reduced in the annealing process. The Si oxide generated by the corrosion may cause a problem that it cannot be reduced in the annealing process.
This invention is made paying attention to the above problems, and it aims at providing the manufacturing equipment and manufacturing method of a steel plate which can suppress generation | occurrence | production of the pattern-like defect in the surface of a steel strip. And

In order to solve the above problems, among the present invention, the invention described in claim 1, wherein the disposed at the conveying direction downstream of the steel strip than the cleaning equipment for cleaning the surface of the steel strip, coming is and transported Ringer roll to remove moisture from the surface of the steel strip,
A dryer that is disposed downstream of the ringer roll in the conveying direction of the steel strip and that dries the surface of the steel strip on the entry side of the continuous annealing furnace;
A steel plate manufacturing facility, comprising: a spraying facility that is disposed between the ringer roll and the dryer and sprays mist-like cooling water onto the surface of the steel strip.

According to the present invention, the spraying equipment for spraying mist-like cooling water onto the surface of the steel strip is arranged between the ringer roll and the dryer arranged downstream of the cleaning equipment in the transport direction of the steel strip.
For this reason, even if moisture remains locally on the surface of the steel strip, it is applied to the surface of the steel strip conveyed from the ringer roll to the dryer by the mist-like cooling water sprayed on the surface of the steel strip. On the other hand, it is possible to form a water film as a whole.

Next, of the present invention, the invention described in claim 2 is the invention described in claim 1, wherein the spray amount of the mist-like cooling water is 150 g / m ² or more and 350 g / m ² or less. It is characterized by being within the range.
According to the present invention, the spray amount of the mist-like cooling water sprayed on the surface of the steel strip is in the range of 150 g / m ² or more and 350 g / m ² or less.

For this reason, compared with the case where the spray amount of the mist-like cooling water sprayed on the surface of the steel strip is less than 150 g / m ^2, it becomes possible to improve the degree of formation of the water film on the surface of the steel strip. . In addition, the amount of residual moisture on the surface of the steel strip exceeds the drying capacity of the dryer as compared with the case where the spray amount of the mist-like cooling water sprayed on the surface of the steel strip is set to an amount exceeding 350 g / m ^2. Can be prevented.

Next, of the present invention, the invention described in claim 3 is the invention described in claim 1 or 2, wherein the temperature of the mist-like cooling water is set to 30 ° C. or less. It is what.
According to the present invention, the temperature of the mist-like cooling water sprayed on the surface of the steel strip by the spray equipment is set to 30 ° C. or less.
For this reason, compared with the case where the temperature of cooling water is set to a temperature exceeding 30 ° C., even when the temperature of the steel strip is 100 ° C. or higher, the mist of cooling water sprayed by the spray equipment It becomes possible to cool the temperature of the steel strip to room temperature.

Next, of the present invention, the invention described in claim 4 is the invention described in any one of claims 1 to 3, wherein the steel strip is a steel strip containing Si. It is characterized by being.
According to the present invention, the steel strip is a steel strip containing Si.
For this reason, it becomes possible to suppress local electrical corrosion of Si generated on the surface of the steel strip by the water film formed on the entire surface of the steel strip conveyed from the ringer roll to the dryer. It becomes possible to suppress generation of local Si oxides generated on the surface of the steel strip. In particular, the effect is large when applied to a steel strip having a Si content of 0.20 [mass%] or more.

Next, of the present invention, the invention described in claim 5, disposed at the conveying direction downstream of the steel strip than the cleaning equipment for cleaning the surface of the steel strip, and from the conveyed surface of the steel strip Between the ringer roll that removes moisture and the dryer that is disposed downstream of the ringer roll in the conveying direction of the steel strip and that dries the surface of the steel strip on the entry side of the continuous annealing furnace, It is a manufacturing method of a steel plate characterized by spraying mist-like cooling water on the surface.
According to the present invention, the mist-like cooling water is sprayed on the surface of the steel strip between the ringer roll and the dryer disposed downstream of the cleaning facility in the steel strip conveyance direction .
For this reason, even if moisture remains locally on the surface of the steel strip, it is applied to the surface of the steel strip conveyed from the ringer roll to the dryer by the mist-like cooling water sprayed on the surface of the steel strip. On the other hand, it is possible to form a water film as a whole.

According to the present invention, between the ringer roll and the dryer, the water film is entirely formed on the surface of the steel strip conveyed from the ringer roll to the dryer by the mist-like cooling water sprayed on the surface of the steel strip. Once formed, this water film can be integrated with the locally remaining water.
For this reason, when moisture remaining on the surface of the steel strip evaporates by the dryer, it becomes possible to suppress the contact between the surface of the steel strip and the air with respect to the surface of the steel strip as a whole. In the entrance side of the continuous annealing furnace, local corrosion occurring in the steel strip can be suppressed.

It is a figure which shows schematic structure of the steel plate manufacturing equipment of 1st embodiment of this invention. It is a figure which shows the relationship between the generation | occurrence | production situation of the local stain in the surface of a steel strip, and the amount of mist spraying. It is a figure which shows schematic structure of the steel plate manufacturing equipment of a prior art example. It is a figure which shows the production | generation of Si oxide in the surface of a steel strip.

(First embodiment)
Hereinafter, a first embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described with reference to the drawings.
(Constitution)
First, the structure of the steel plate manufacturing facility of the present embodiment (hereinafter referred to as “steel plate manufacturing facility”) will be described with reference to FIG.
FIG. 1 is a diagram showing a schematic configuration of the steel sheet manufacturing facility of the present embodiment. In FIG. 1, the same components as those shown in FIGS. 3 and 4 are denoted by the same reference numerals.
In the steel sheet manufacturing facility 1, before performing continuous annealing in a continuous annealing furnace (not shown), the cleaning process of the rolling oil adhering to the surface of the steel strip C and the moisture for removing the water adhering to the surface of the steel strip C are removed. A removal process is performed.

The water removal step is a step performed after the cleaning step, as in the conventional cold-rolled steel plate manufacturing process described above, and uses the water draining operation by the ringer roll 2 and the dryer 4 on the surface of the steel strip C. This is a process for carrying out the drying operation.
Moreover, the steel plate manufacturing facility 1 is provided with a ringer roll 2, a dryer 4, and a spraying facility 6, as shown in FIG.

The ringer roll 2 is a cylindrical (roll-shaped) member formed using an elastic material such as rubber, and is pressed against the surface of the steel strip C being conveyed in a state of being rotatably installed. ing. In addition, in FIG. 1, the conveyance direction of the steel strip C is shown by the arrow.
The ringer rolls 2 are composed of two pairs, and each set of the ringer rolls 2 includes one surface of the steel strip C (for example, the right surface in FIG. 1) and the steel strip. It is pressed to the other surface of C (for example, the left surface in FIG. 1). In addition, in FIG. 1, the case where the structure of the steel plate manufacturing equipment 1 is set as the structure provided with two sets of ringer rolls 2 is shown as an example.

Moreover, the ringer roll 2 is arrange | positioned in the conveyance direction of the steel strip C in the steel plate manufacturing equipment 1 rather than the washing equipment 8 (hot rinse). Here, the cleaning facility 8 is a facility that performs the above-described cleaning process using, for example, hot water of about 80 [° C.].
As described above, the ringer roll 2 pressed against the surface of the steel strip C transported from the cleaning facility 8 rotates with the transport of the steel strip C, and moisture (warm water) adhering to the surface of the steel strip C is rotated. ) Is removed from the surface of the steel strip C.

The dryer 4 is disposed downstream of the ringer roll 2 in the conveying direction of the steel strip C, and is disposed on the entry side (downstream in the conveying direction of the steel strip C) of the continuous annealing furnace (not shown). .
The dryer 4 is arrange | positioned so that the hot air of about 100-150 [degreeC] can be sprayed toward the steel strip C, specifically, both surfaces (front surface, back surface) of the steel strip C, for example.
By the above, the dryer 4 which blows a hot air on the steel strip C conveyed from the ringer roll 2 dries the surface of the steel strip C in the entrance side of a continuous annealing furnace.

The spray facility 6 includes a cooling water tank 10, a temperature adjustment unit 12, a spray pump 14, a spray unit 16, and a spray controller 18.
The cooling water tank 10 is a tank that stores cooling water for spraying the steel strip C from the spraying section 16.
The temperature adjustment unit 12 is provided in the cooling water tank 10 and adjusts the temperature (water temperature) of the liquid stored in the cooling water tank 10 based on a temperature adjustment command signal output from the spray controller 18.

The spraying pump 14 is connected to the cooling water tank 10 via a pipe, and discharges the liquid stored in the cooling water tank 10 to the spraying unit 16.
Further, the spray pump 14 adjusts the discharge amount of the liquid discharged to the spray unit 16 based on the spray amount command signal output from the spray controller 18.
The spray unit 16 has a spray nozzle (not shown), and sprays the liquid (cooling water) discharged from the spray pump 14 into a mist (mist) state and sprays it toward the surface of the steel strip C. Spray from.

Here, the configuration of the spray nozzle is such that the shape of the spray port for spraying the cooling water, for example, the cooling water discharged from the spray pump 14 is a mist with an average particle diameter of 50 [μm] or less. The structure is formed in a possible shape.
Further, the spray nozzle has a mist-like cooling in the range of 580 to 750 [mm] from the center of the ringer roll 2 along the width direction of the ringer roll 2, for example. It is set as the structure formed so that water could be sprayed. This configuration is applied when the width of the steel strip C is, for example, 1000 [mm].

  Moreover, the spraying part 16 is comprised by 2 sets, and these 1 set of spraying parts 16 respectively set the nozzle for spraying to one surface (for example, right side surface in FIG. 1). ) And the other surface of the steel strip C (for example, the left surface in FIG. 1). In addition, in FIG. 1, the case where the structure of the steel plate manufacturing equipment 1 is set as the structure provided with a set of spraying parts 16 is shown as an example.

The spray controller 18 is a liquid stored in the cooling water tank 10 so that the temperature of the cooling water sprayed from the spraying nozzle of the spray unit 16 toward the surface of the steel strip C becomes a preset temperature. Calculate the temperature. Then, the spray controller 18 outputs a temperature adjustment command signal including the calculated temperature to the temperature adjustment unit 12.
Here, in this embodiment, as an example, the cooling water tank 10 is configured so that the temperature of the cooling water sprayed by the spray controller 18 from the spray nozzle toward the surface of the steel strip C is 30 [° C.] or less. The case of calculating the temperature of the liquid stored in the container will be described.

  Moreover, the spray controller 18 sprays the spray pump 14 so that the spray amount of the cooling water sprayed from the spray nozzle of the spray unit 16 toward the surface of the steel strip C becomes a preset spray amount. The discharge amount of the liquid discharged to the unit 16 is calculated. Then, the spray controller 18 outputs a spray amount command signal including the calculated discharge amount to the spray pump 14.

Here, in this embodiment, the spray amount (for example, spray amount per second) of the mist-like cooling water sprayed by the spray controller 18 toward the surface of the steel strip C from the spray nozzle is an example. The case where the discharge amount of the liquid discharged from the spray pump 14 to the spray unit 16 is calculated so as to be in the range of 150 g / m ^{2 to} 350 g / m ² will be described.
As described above, the spraying facility 6 is disposed between the ringer roll 2 and the dryer 4 and sprays mist (mist) cooling water onto the surface (both sides) of the steel strip C.
Moreover, in this embodiment, the case where the steel strip C is a steel strip containing Si (Si steel strip) is demonstrated as an example.

(Operation, action, etc.)
Hereinafter, with reference to FIG. 1 and FIGS. 3 and 4, operations and actions performed by the steel sheet manufacturing facility 1 having the above-described configuration will be described using FIG. 2.
When a cold-rolled steel sheet is manufactured using the steel sheet manufacturing facility 1 of the present embodiment, the steel strip C paid out from the payoff reel 20 is subjected to a cleaning process in the cleaning facility 8 and then moved in the transport direction. It moves along, and a moisture removal process is performed.
In the moisture removal step, the steel strip C being conveyed is pressed by a set of ringer rolls 2. The pair of ringer rolls 2 rotate while pressing the surface (both sides) of the steel strip C to convey the steel strip C, and moisture (warm water) adhering to the surface of the steel strip C in the cleaning equipment 8. Is removed from the surface of the steel strip C.

And on the surface (both sides) of the steel strip C that has passed between the pair of ringer rolls 2, the temperature is set to 30 [° C.] or less and the spray amount is 150 g from the spray nozzle of the spray unit 16. A mist of cooling water set in a range of not less than / m ^{2 and not} more than 350 g / m ² is sprayed.
For this reason, a water film is formed entirely on the surface of the steel strip C sprayed with the cooling water from the spray nozzles of the spray section 16 by the mist (mist) cooling water.

The steel strip C in which a water film is entirely formed on the surface moves to the dryer 4 along the conveying direction, and remains on the surface on the entry side of the continuous annealing furnace by the warm air blown by the dryer 4. Moisture is evaporated and the surface is dried.
Here, in the steel plate manufacturing facility 1 of the present embodiment, a water film is formed entirely on the surface of the steel strip C before being transported to the dryer 4 by the mist-like cooling water sprayed from the spray nozzle. ing.

For this reason, when the moisture remaining on the surface of the steel strip C is evaporated by the dryer 4, the contact between the surface of the steel strip C and the air can be entirely suppressed with respect to the surface of the steel strip C. It becomes possible.
Thereby, in the ringer roll 2, even if the water adhering to the surface of the steel strip C cannot be completely removed and the water remains locally on the surface of the steel strip C, locally The remaining moisture can be integrated with the water film.

Therefore, it becomes possible for moisture to be present entirely on the surface of the steel strip C, and local corrosion occurring in the steel strip C can be suppressed on the entry side of the continuous annealing furnace.
Moreover, in the steel plate manufacturing facility 1 of the present embodiment, the atomized cooling water in which the spray amount is set within the range of 150 g / m ² or more and 350 g / m ² or less from the spray nozzle of the spray unit 16 is used as a steel strip. Spray onto the surface of C.

Therefore, as shown in FIG. 2, when the spray amount of the mist-like cooling water is less than 150 g / m ² or when the spray amount of the mist-like cooling water is set to a value exceeding 350 g / m ² In comparison, the occurrence of local stains (pattern defects) on the surface of the steel strip C can be suppressed. FIG. 2 is a diagram showing a relationship between a local stain generation state on the surface of the steel strip C and a mist (mist-like cooling water) spray amount. In FIG. 2, the vertical axis of the graph indicates the occurrence of stain, and the horizontal axis of the graph indicates the mist spray amount [g / m ² ].

That is, as described above, by setting the spray amount of the mist-like cooling water within the range of 150 g / m ² or more and 350 g / m ² or less, the mist-like cooling water spray amount suppresses the generation of stains. Therefore, an appropriate amount (“appropriate spray amount” shown in FIG. 2) is obtained.
On the other hand, when the spray amount of the mist-like cooling water is set to less than 150 g / m ² , as shown in FIG. 2, the water film formed on the surface of the steel strip C is insufficient (the “water” shown in FIG. Insufficient film ”), and in particular, wear occurs in the portion of the Ringer roll 2 that presses the edge portion of the steel strip C. In the steel strip C, stain is generated at a portion facing the portion where wear has occurred ("edge stain generation" shown in FIG. 2).

When the spray amount of the mist-like cooling water is set to a value exceeding 350 g / m ² , the water film formed on the surface of the steel strip C is sufficiently dried by the dryer 4 as shown in FIG. (“Drying failure” shown in FIG. 2), annealing is performed in a state where the entire water film is formed on the surface of the steel strip C. Then, the entire stain is generated on the surface of the steel strip C (“full stain occurrence” shown in FIG. 2).

In addition, as mentioned above, the steel plate manufacturing method (steel plate manufacturing method) performed by the operation of the steel plate manufacturing facility 1 of the present embodiment is mist-like on the surface of the steel strip C between the ringer roll 2 and the dryer 4. This is a method of spraying the cooling water.
Moreover, after fully drying with the dryer 4, the steel strip C is moved to continuous annealing. Here, as preferable conditions for continuous annealing, annealing is performed at an annealing temperature of 730 to 880 [° C.], a soaking time of 100 to 600 seconds, and an atmosphere (H ₂ concentration) of 5 to 10%, and an average cooling rate is set. Conditions for cooling at 5 to 50 [° C./s] can be mentioned.

(Effects of the first embodiment)
The effects of this embodiment are listed below.
(1) In the steel plate manufacturing facility 1 of the present embodiment, a spray facility 6 for spraying mist-like cooling water onto the surface of the steel strip C is disposed between the ringer roll 2 and the dryer 4.
For this reason, even when moisture remains locally on the surface of the steel strip C, the steel conveyed from the ringer roll 2 to the dryer 4 by the mist-like cooling water sprayed on the surface of the steel strip C. A water film can be formed on the entire surface of the band C.

As a result, even if moisture remains locally on the surface of the steel strip C, the water film formed entirely on the surface of the steel strip C is reduced with the locally remaining moisture. It can be integrated.
Thereby, when the water | moisture content which remains on the surface of the steel strip C evaporates with the dryer 4, it suppresses the contact with the surface of the steel strip C and the air with respect to the surface of the steel strip C entirely. Therefore, local corrosion occurring in the steel strip C can be suppressed on the entry side of the continuous annealing furnace.
Therefore, it is possible to suppress the occurrence of pattern defects (stains) on the surface of the steel strip C.

Moreover, even if wear occurs in the portion of the ringer roll 2 that presses the edge portion of the steel strip C, local corrosion that occurs in the steel strip C can be suppressed without replacing the ringer roll 2. It becomes possible.
For this reason, it becomes possible to suppress the production loss accompanying the replacement of the ringer roll 2 and the increase in production cost, and to suppress the occurrence of stain on the surface of the steel strip C.

(2) In the steel plate manufacturing facility 1 of the present embodiment, the spraying facility 6 sets the spray amount of the mist-like cooling water sprayed on the surface of the steel strip C within the range of 150 g / m ² or more and 350 g / m ² or less. Yes.
For this reason, it becomes possible for the spray equipment 6 to improve the formation degree of the water film on the surface of the steel strip C, compared with the case where the spray amount of the mist-like cooling water is less than 150 g / m ² . In addition, the amount of water remaining on the surface of the steel strip C exceeds the drying capacity of the dryer 4 as compared with the case where the spray facility 6 sets the spray amount of the mist-like cooling water to an amount exceeding 350 g / m ^2. Can be prevented.
As a result, the spray equipment 6 has a pattern on the surface of the steel strip C as compared with the case where the spray amount of the mist-like cooling water is less than 150 g / m ² or more than 350 g / m ^2. It is possible to suppress the occurrence of a state defect (stain).

(3) In the steel plate manufacturing facility 1 of the present embodiment, the temperature of the mist-like cooling water sprayed by the spray facility 6 on the surface of the steel strip C is set to 30 ° C. or less.
For this reason, even when the temperature of the steel strip C is 100 ° C. or higher, the temperature of the steel strip C can be cooled to room temperature by the mist-like cooling water sprayed by the spray equipment 6. It is possible to form a stable water film as compared with the case where the temperature is set to a temperature exceeding 30 ° C.
As a result, when the water remaining on the surface of the steel strip C is evaporated by the dryer 4, the surface of the steel strip C and the air are compared with the case where the temperature of the cooling water is higher than 30 ° C. Therefore, the occurrence of pattern defects (stains) on the surface of the steel strip C can be suppressed.

(4) In the steel plate manufacturing facility 1 of the present embodiment, the steel strip C is a steel strip containing Si (Si steel strip).
For this reason, local electric corrosion of Si generated on the surface of the steel strip C is suppressed by the water film formed on the entire surface of the steel strip C conveyed from the ringer roll 2 to the dryer 4. Is possible.
As a result, it is possible to suppress the generation of local Si oxides generated on the surface of the steel strip C, and it is possible to suppress the occurrence of pattern defects (stains) on the surface of the steel strip C. .

(5) In the steel plate manufacturing method of the present embodiment, mist-like cooling water is sprayed on the surface of the steel strip C between the ringer roll 2 and the dryer 4.
For this reason, even when moisture remains locally on the surface of the steel strip C, the steel conveyed from the ringer roll 2 to the dryer 4 by the mist-like cooling water sprayed on the surface of the steel strip C. A water film can be formed on the entire surface of the strip C, and the occurrence of pattern defects (stains) on the surface of the steel strip C can be suppressed.
As a result, it is possible to suppress the production loss accompanying the replacement of the ringer roll 2 and the increase in production cost, and it is possible to suppress the occurrence of stain on the surface of the steel strip C.

(Modification)
Hereinafter, modifications of the present embodiment will be described.
(1) In the steel plate manufacturing facility 1 of the present embodiment, the spray amount of the mist-like cooling water sprayed on the surface of the steel strip C by the spray facility 6 is within a range of 150 g / m ² or more and 350 g / m ² or less. However, the present invention is not limited to this. That is, the spray amount per second of the mist-like cooling water may be set to a value less than 150 g / m ² or more than 350 g / m ² .
(2) In the steel plate manufacturing facility 1 of the present embodiment, the temperature of the mist-like cooling water sprayed on the surface of the steel strip C by the spray facility 6 is set to 30 ° C. or lower, but is not limited thereto. The temperature of the cooling water may be a temperature exceeding 30 ° C.

(Example)
Hereinafter, with reference to FIG. 1 to FIG. 4, the results of verifying the effects of the steel plate manufacturing facility of the present invention example using the steel plate manufacturing facility of the comparative example and the present invention example will be described. In addition, the structure of the steel plate manufacturing equipment 1 and the steel strip C of the example of this invention used for verification of an effect is shown below.
Ringer roll 2 radius: 150 [mm]
Distance between the surface of the steel strip C and the spray part 16: 300 [mm]
Mist spray amount (mist spray amount of cooling water): 250 [g / m ² ]
Water temperature: 20 [° C]
Average particle size: 50 [μm] or less Dryer temperature: 100-150 [° C.]
Hot rinse temperature: 80 [° C]
Mist spray position in the width direction: 580 to 750 [mm] from the center in the width direction of the ringer roll 2, respectively.
Steel strip C dimensions: plate thickness 1.2 [mm], plate width 1000 [mm]
Component of steel strip C: mass [%], C: 0.08 [%], Si: 0.25 [%], Mn: 1.55 [%], P: 0.030 [%], S: 0.002 [%], balance of Fe and inevitable impurities

On the other hand, the steel plate manufacturing facility 1 of the comparative example has the configuration of the above-described conventional example (see FIG. 3). That is, the configuration of the steel plate manufacturing facility 1 of the comparative example is the same as the configuration of the steel plate manufacturing facility 1 of the present invention except that the spraying facility 6 is not provided.
Next, using the steel sheet manufacturing equipment 1 of the present invention example and the comparative example, the steel strip C is passed through to produce a cold-rolled steel sheet, the occurrence rate of pattern defects is detected, and the detected occurrence rate is compared. The results will be described.

When detecting the occurrence rate of pattern defects, the steel strip production facility 1 of the present invention example and the comparative example is passed through a steel strip C of 30000 [km] to produce a cold-rolled steel plate. did.
And as a result of detecting the generation | occurrence | production ratio of a pattern-like defect with respect to the cold-rolled steel plate manufactured using the steel plate manufacturing equipment 1 of this invention example and a comparative example, the cold rolling manufactured using the steel plate manufacturing equipment 1 of this invention example The steel sheet was detected to have a pattern defect occurrence rate of 5%.

On the other hand, the cold-rolled steel plate manufactured using the steel plate manufacturing facility 1 of the comparative example was detected to have a pattern defect occurrence rate of 22 [%]. The occurrence rate (%) of pattern defects is calculated by the following equation.
Occurrence rate of pattern defects =
{Number of coils with stain / total number of coils (for 30,000 km)} x 100 (%)
Therefore, it was confirmed that the steel plate manufacturing facility 1 of the present invention example can reduce the occurrence rate of pattern defects in the manufactured cold-rolled steel plate as compared with the steel plate manufacturing facility 1 of the comparative example.

DESCRIPTION OF SYMBOLS 1 Steel plate manufacturing equipment 2 Ringer roll 4 Dryer 6 Spraying equipment 8 Cleaning equipment 10 Cooling water tank 12 Temperature control part 14 Spraying pump 16 Spraying part 18 Spraying controller 20 Payoff reel 22 Continuous annealing furnace C Steel strip

Claims (5)

Than washing equipment to clean the surface of the strip is disposed at the conveying direction downstream of said steel strip, and wringer roll for removing moisture from and the conveyed surface of the steel strip,
A dryer that is disposed downstream of the ringer roll in the conveying direction of the steel strip and that dries the surface of the steel strip on the entry side of the continuous annealing furnace;
A steel plate manufacturing facility, comprising: a spraying facility that is disposed between the ringer roll and the dryer and sprays mist-like cooling water onto the surface of the steel strip. ^{2. The} steel sheet manufacturing facility according to claim 1, wherein the spray amount of the mist-like cooling water is within a range of 150 g / m ² or more and 350 g / m ² or less.   The steel sheet manufacturing facility according to claim 1 or 2, wherein the temperature of the mist-like cooling water is 30 ° C or lower.   The steel strip manufacturing equipment according to any one of claims 1 to 3, wherein the steel strip is a steel strip containing Si. Than washing equipment to clean the surface of the strip is disposed at the conveying direction downstream of said steel strip, and a wringer roll for removing moisture from the conveyed surface of the steel strip, the steel strip than the wringer roll A steel plate characterized by spraying mist-like cooling water onto the surface of the steel strip between the dryer disposed on the downstream side in the conveying direction and drying the surface of the steel strip on the entry side of the continuous annealing furnace. Production method.

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