KR102109260B1 - Crack forming unit and descaling apparatus having thereof - Google Patents

Abstract

Crack forming unit according to an embodiment of the present invention is provided on the housing member and the housing member disposed on the conveying path of the steel sheet, which respectively contact the upper and lower surfaces of the steel sheet, and the linear velocity of the part contacting the steel sheet May include a pair of different defect forming roll members.

Description

Crack forming unit and descaling apparatus including the same

The present invention relates to a crack forming unit and a scale removing device comprising the same.

On the hot rolled carbon steel and high strength steel surfaces, a scale layer of about 5 to 10 micrometers thick is produced. In general, the scale layer of hot-rolled carbon steel is separated by a transformation process of the scale layer when it is air-cooled in a winding process, and when further cooling is continued, only a very thin scale layer of 1 micrometer or less remains in the surface layer.

In order to remove the thin scale layer, a conventional method for removing the scale is a method of chemically removing the hot-rolled scale from the surface of the steel sheet using strong acid such as hydrochloric acid.

However, such a method for removing scale by strong acid has a problem of increasing the length of a facility due to the use of a number of pickling tanks and a water washing tank, a problem of inhibiting the working environment due to the generation of acid vapors, a problem of causing environmental hazards due to waste acid treatment, acid recovery and acid resistant equipment A number of problems have been pointed out, such as the problem of increasing the number of additional facilities due to the like, the problem of the difference in the ability to remove the scale depending on the steel type, and the problem of quality defects in the steel solution tank and the washing tank in the acid solution tank when the line is stopped.

Therefore, in order to replace the chemical scale removal method by the acid solution, a metal shot ball or grit, or a slurry obtained by mixing a metal shot ball or grit with water, is sprayed onto the surface of the steel sheet to physically As a result, attempts have been made to remove the scale of the surface of the steel sheet, but most of them have been used in combination with the pickling process as a pretreatment process to increase the pickling efficiency. That is, it contains the problems of the conventional scale removal technique described above.

Therefore, it is necessary to study a crack forming unit and a scale removing device including the same to improve the above-mentioned problems.

Korean Application No. 10-2012-0154484

An object of the present invention is to provide a crack forming unit for efficiently removing the scale formed on a steel sheet and a scale removing device including the same.

Crack forming unit according to an embodiment of the present invention is provided on the housing member and the housing member disposed on the conveying path of the steel sheet, which respectively contact the upper and lower surfaces of the steel sheet, and the linear velocity of the part contacting the steel sheet May include a pair of different defect forming roll members.

And, the crack-forming roll member of the crack forming unit according to an embodiment of the present invention is in contact with a small diameter roll and the other surface of the steel plate, which are in contact with one surface of the steel plate, and rotates at the same rotational speed as the small diameter roll, It may include a large diameter roll having a larger diameter than the small diameter roll.

Or the crack forming unit of the crack forming unit according to an embodiment of the present invention, the upper diameter roll which is in contact with the upper surface of the steel sheet and the lower surface of the steel sheet, rotates at a different rotational speed than the upper diameter roll , It may include a lower diameter roll formed in the same diameter as the upper diameter roll.

In addition, the crack-forming roll member of the crack forming unit according to an embodiment of the present invention, the first roll portion, the second roll portion and the third roll portion provided in each of the housing members in order on the transport path of the steel sheet It may include a roll portion, and the second roll portion may be characterized in that different linear velocity ratios of portions in contact with the upper and lower surfaces of the steel sheet are formed opposite to the linear velocity ratios of the first and third roll portions. .

Alternatively, the crack-forming roll member of the crack forming unit according to an embodiment of the present invention includes a first roll part, a second roll part, and a third roll provided on the housing member in a pair in order on the transport path of the steel sheet. It may include a portion, the second roll portion, it may be characterized in that the first roll portion and the third roll portion is disposed biased upward or downward on the line connecting the.

Alternatively, the crack-forming roll member of the crack forming unit according to an embodiment of the present invention includes a first roll part, a second roll part, and a third roll provided on the housing member in a pair in order on the transport path of the steel sheet. It may include a portion, the first roll portion is rotated in the reverse direction to the conveying direction of the steel plate, the third roll portion may be characterized in that rotated in the forward direction in the conveying direction of the steel sheet.

Here, the crack forming roll member of the crack forming unit according to an embodiment of the present invention may be characterized in that the steel sheet is pressed at a rolling reduction rate of 1 to 10%.

The scale removing apparatus according to another embodiment of the present invention is provided downstream of the crack forming unit and the crack forming unit on the transport path of the steel sheet, and the spray unit spraying the abrasive slurry mixed with abrasives and high pressure fluid into the steel sheet. It may include.

In addition, the scale removing device according to another embodiment of the present invention is provided downstream on the conveying path of the steel sheet than the spraying unit, and the washing unit spraying the washing water onto the steel sheet and downstream of the conveying path of the steel sheet than the washing unit It is provided in, it may include a dry unit for injecting air to the steel sheet.

The crack forming unit of the present invention and the scale removing device including the same have the advantage of efficiently performing physical removal of the scale formed on the steel sheet.

In another aspect, the crack forming unit of the present invention and the scale removing device including the same can eliminate the existing pickling process in the process of continuously removing the scale on the steel sheet, resulting in acid vapor generation, acid recovery And waste acid treatment, an increase in equipment length, an increase in manufacturing cost, and a difference in scale removal ability according to steel types.

However, various and advantageous advantages and effects of the present invention are not limited to the above, and may be more easily understood in the process of describing the specific embodiment of the present invention.

1 is a block diagram showing a crack forming unit of the present invention and a scale removing device including the same.
Figure 2 shows an embodiment in which the crack-forming roll member in the crack forming unit of the present invention includes a small diameter roll and a large diameter roll.
Figure 3 shows an embodiment in which the crack-forming roll member in the crack forming unit of the present invention includes an upper diameter roll and a lower diameter roll.
4 shows an embodiment in which the crack forming roll member is divided into a first roll part, a second roll part, and a third roll part in the crack forming unit of the present invention, and the second roll part is vertically disposed.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. The shape and size of elements in the drawings may be exaggerated for a more clear description.

In addition, in this specification, a singular expression includes a plural expression unless the context clearly indicates otherwise, and the same reference numerals or reference numerals assigned in a similar manner throughout the specification refer to the same or corresponding components. Let's do it.

The present invention relates to a crack forming unit (1) and a scale removing device comprising the same, it is possible to efficiently proceed to the physical removal of the scale formed on the steel sheet (S), in another aspect, the scale on the steel sheet (S) continuously In the process of removing, the existing pickling process can be omitted, resulting in acid vapor generation problems, acid recovery and waste acid treatment problems, equipment length increase problems, manufacturing cost increase problems, and differences in scale removal ability according to steel types You can solve the back.

Specifically, referring to the drawings, FIG. 1 is a configuration diagram showing a crack forming unit 1 of the present invention and a scale removing device including the same, and according to the drawings, crack formation according to an embodiment of the present invention The unit 1 is provided on the housing member 10 and the housing member 10 disposed on the transport path of the steel sheet S, and respectively contact the upper and lower surfaces of the steel sheet S, and the steel sheet S ) May include a pair of flaw forming roll members 20 having different linear velocities.

As described above, in the crack forming unit 1 of the present invention, the line speed at the contact surface with the steel sheet S is differently formed at the upper and lower surfaces while the flaw forming roll member 20 contacts the upper and lower surfaces of the steel sheet S. Therefore, micro cracks are generated by slipping with an oxide scale or the like formed on the steel sheet S.

After the collision of the abrasive slurry and the scale sprayed from the spraying unit 2, etc., the crack formed on the scale in the crack forming unit 1 of the present invention serves to facilitate the separation of the scale from the steel sheet S Is done.

The housing member 10 serves as a body provided with the defect forming roll member 20, and more specifically, a small diameter roll 21 and a large diameter roll 22 of the defect forming roll member 20. , The upper diameter roll 23, the lower diameter roll 24 to the first roll portion 20a, the second roll portion 20b and the third roll portion 20c are provided to be rotated.

In addition, the housing member 10 is disposed on the moving path of the steel sheet S so that the defect forming roll member 20 can contact the steel sheet S.

The flaw forming roll member 20 serves to form fine cracks due to slip due to a difference in linear velocity between the upper and lower surfaces when contacting the steel sheet S. To this end, the flaw forming roll member 20 is provided in a pair in which the linear speeds of the upper and lower parts contacting the steel sheet S are different from each other.

Specifically, the rotational speed on the rotating shaft is the same and is provided with a small diameter roll 21 and a large diameter roll 22 having a difference in diameter, and as a result, a difference occurs in the linear speed at the contact portion with the steel sheet S. Can be configured. This will be described later in detail with reference to FIG. 2.

In addition, the diameters are the same, but the rotation speed in the rotating shaft is provided with different upper diameter rolls 23 and lower diameter rolls 24, and as a result, a difference occurs in the linear speed at the contact portion with the steel sheet S. Can be configured. This will be described later in detail with reference to FIG. 3.

Further, the flaw forming roll member 20 may be divided into a first roll portion 20a, a second roll portion 20b, and a third roll portion 20c. That is, the flaw forming roll member 20 is provided in three sets, and is divided into a first roll portion 20a, a second roll portion 20b, and a third roll portion 20c, respectively. Crack generation and roughness formation for the scale of the phase S) can be adjusted. This will be described later with reference to FIGS. 2 to 4.

Meanwhile, the flaw forming roll member 20 of the crack forming unit 1 according to an embodiment of the present invention may be characterized in that the steel sheet S is pressed at a rolling reduction rate of 1 to 10%.

That is, by rolling the steel sheet (S) with a rolling reduction of 1 to 10% by the flaw forming roll member (20), a high-density crack is formed in the scale layer formed on the surface of the steel sheet (S) and the scale layer thus changed The silver abrasive slurry can be removed from the steel sheet S more easily and efficiently during high pressure injection.

If the reduction ratio is too low (1% or less), the formation of scale layer cracks in the target steel sheet (S) is insufficient, resulting in reduced scale removal efficiency. If it is too high (10% or more), the material of the steel sheet (S) may be affected. There is a problem that the surface whiteness is reduced after removing the scale because the scale is strongly adhered to the steel strip due to excessive pressing force.

As such, by rolling the steel sheet (S) with a rolling reduction of 1 to 10% by the flaw forming roll member 20, residual scale removal and roughness can be lowered, as can be seen from the experimental data in Table 1 below. have.

In the experiment of Table 1, the abrasive of the abrasive slurry was about 150 to 200 microns in size, and the spray pressure was about 300 bar and the spray angle was about 15 degrees.

division Rolling down rate (%) Linear velocity
(rpm) Residual scale (%) Illuminance (㎛) 1st roll part Second roll part Third roll part Top bottom Top bottom Top bottom Comparative Example 1-1 0.5 20 30 30 20 20 30 5 2.5 Inventive Example 1-1 One 20 30 30 20 20 30 0.8 1.0 Inventive Example 1-2 3 20 30 30 20 20 30 0.8 1.1 Inventive Example 1-3 5 20 30 30 20 20 30 0.5 1.2 Inventive Example 1-4 7 20 30 30 20 20 30 0.5 1.2 Inventive Example 1-5 10 20 30 30 20 20 30 0.6 1.2 Comparative Example 1-2 11 20 30 30 20 20 30 3 2.0

The scale removing apparatus according to another embodiment of the present invention is provided downstream of the crack forming unit 1 and the crack forming unit 1 on the transport path of the steel sheet S, and the steel sheet S is used for It may include an injection unit (2) for spraying the abrasive slurry mixed with high pressure fluid.

In other words, while the crack forming unit 1 contacts the upper and lower surfaces of the steel sheet S by the flaw forming roll member 20, the linear velocity at the contact surface with the steel sheet S is differently formed on the upper and lower surfaces. When a fine crack is caused by slip with an oxide scale or the like formed on the steel sheet S, the polishing slurry is sprayed from the spraying unit 2 to form a scale when the polishing slurry collides with the scale. It is possible to facilitate the separation of the scale from the steel sheet S by one crack.

When the crack is generated on the scale on the steel plate S by the crack forming unit 1, the spray unit 2 serves to spray the polishing slurry on the steel plate S to remove the scale. .

To this end, the injection unit 2 is mixed with abrasives and a high-pressure fluid to form an abrasive slurry to spray onto the steel sheet S.

For example, as the type of abrasive, silicon oxide, silicon carbide, aluminum oxide, glass beads, and ceramic beads are used, and most preferably, glass beads or ceramic beads are used as abrasives.

When the size of the abrasive is less than 10 micrometers, the scale removal is insufficient, and when using more than 400 micrometers, the surface roughness is too large to secure the target surface quality, from 10 micrometers or more in diameter to 400 micrometers or less Use that.

Then, the high pressure fluid forms water into high pressure water by a high pressure pump, and mixes with the abrasive to form a polishing slurry.

When high pressure spraying of abrasive slurry, the injection pressure of high pressure water is less than 100 bar, the scale removal efficiency is insufficient, and when the pressure is more than 500 bar, the surface roughness of the hot rolled steel sheet (S) increases, resulting in an increase in power and equipment costs. The range of bar is suitable.

In addition, the scale removing device according to another embodiment of the present invention is provided downstream of the transport path of the steel sheet S than the spray unit 2, and the washing unit 3 sprays washing water with the steel sheet S And it is provided downstream of the transport path of the steel plate (S) than the washing unit (3), may include a dry unit (4) for injecting air into the steel plate (S).

The washing unit 3 serves to completely remove the scale that has deviated by spraying the polishing slurry on the steel sheet S, and also remove the polishing slurry remaining on the steel sheet S.

To this end, the washing unit 3 sprays the washing water onto the steel sheet S, and the residual scale, polishing slurry, and the like can be removed by the washing water.

The dry unit 4 serves to remove the washing water sprayed on the steel sheet S with hot air. That is, the washing of the steel sheet S is completed by evaporating the washing water at a high temperature.

In this way, the steel sheet (S) is to remove the scale through the crack forming unit (1), the spray unit (2), the washing unit (3), the dry unit (4), the transfer to the crack forming unit (1) The steel sheet (S) is supplied while the steel sheet (S) wound on the payoff reel (5) is released, and between the payoff reel (5) and the crack forming unit (1) for the supply of continuous steel sheet (S). The welding machine 7 is provided to weld the ends of the steel sheets S to each other.

Then, the steel sheet S from which the scale discharged from the dry unit 4 is removed is wound on the tension reel 6 and is transferred to the outside.

FIG. 2 shows an embodiment in which the crack forming roll member 20 in the crack forming unit 1 of the present invention includes a small diameter roll 21 and a large diameter roll 22. Referring to the drawings, the present invention The flaw forming roll member 20 of the crack forming unit 1 according to an embodiment, is in contact with the small diameter roll 21 and the other surface of the steel sheet (S) contacting one surface of the steel sheet (S), The small diameter roll 21 may rotate at the same rotational speed, and may include a large diameter roll 22 having a larger diameter than the small diameter roll 21.

That is, the rotational speed on the rotating shaft is the same and is provided with a small diameter roll 21 and a large diameter roll 22 having a difference in diameter, and as a result, a difference occurs in the linear speed at the contact portion with the steel sheet S. It can be configured.

When the linear speed is differently configured by the small-diameter roll 21 and the large-diameter roll 22 in this way, the same rotational speed may be applied to the rotating shaft, or the same driving motor for rotation may be used, or one motor. There is an advantage that can be used by sharing.

The defect forming roll member 20 divided into the small diameter roll 21 and the large diameter roll 22 is provided in three sets, respectively, the first roll portion 20a, the second roll portion 20b, and the third roll portion ( 20c).

Here, the rotational speed (v11) of the small diameter roll (21) at the top of the first roll portion (20a) and the rotational speed (v12) of the large diameter roll (22) at the bottom are the same, but a difference in linear speed occurs due to a difference in diameter. do. In addition, the rotation speed (v21) of the large diameter roll (22) at the top of the second roll portion (20b) and the rotation speed (v22) of the small diameter roll (21) at the bottom are the same, but a difference in linear speed occurs due to a difference in diameter. , The rotation speed (v31) of the small diameter roll (21) at the top of the third roll portion (20c) and the rotation speed (v32) of the large diameter roll (22) at the bottom are the same, but a difference in linear speed occurs due to a difference in diameter. .

In addition, referring to Figure 2, the crack forming roll member 20 of the crack forming unit 1 according to an embodiment of the present invention, the housing member in order on the transport path of the steel sheet (S) ( 10) includes a first roll portion 20a, a second roll portion 20b, and a third roll portion 20c, each provided in a pair, wherein the second roll portion 20b includes an upper surface of the steel sheet S and It may be characterized in that different linear velocity ratios of the portions in contact with the lower surface are formed opposite to the linear velocity ratios of the first roll portion 20a and the third roll portion 20c.

In this way, by changing the linear velocity ratio up and down, the surface roughness is kept small while increasing the efficiency of crack formation on the scale, thereby increasing the effect of scaling. This can be seen from the experimental data in Table 2 below.

In the experiment of Table 2, the abrasive material of the abrasive slurry was about 100 microns alumina, the spray pressure was about 250 bar, and the spray angle was about 30 degrees. Then, the first roll portion 20a and the second roll portion 20b are reverse rotation, and the third roll portion 20c is forward rotation.

division Rolling down rate (%) Linear velocity
(rpm) Residual scale (%) Illuminance (㎛) 1st roll part Second roll part Third roll part Top bottom Top bottom Top bottom Comparative Example 2-1 5 20 30 20 30 20 30 6.2 1.0 Comparative Example 2-2 5 20 30 20 30 30 20 4.8 1.2 Comparative Example 2-3 5 20 30 30 20 30 20 4.2 1.2 Inventive Example 2-1 5 20 30 30 20 20 30 1.0 1.4

FIG. 3 shows an embodiment in which the crack forming roll member 20 in the crack forming unit 1 of the present invention includes an upper diameter roll 23 and a lower diameter roll 24. Referring to the drawing, The flaw forming roll member 20 of the crack forming unit 1 according to an embodiment of the present invention, the upper diameter roll 23 and the lower surface of the steel sheet (S) in contact with the upper surface of the steel sheet (S) It may be in contact, and rotates at a different rotational speed from the upper diameter roll 23, and may include a lower diameter roll 24 formed to have the same diameter as the upper diameter roll 23.

That is, the diameter is the same, the rotational speed in the rotating shaft is provided with a different upper diameter roll 23, lower diameter roll 24, as a result, a difference occurs in the linear speed at the contact portion with the steel sheet (S) It can be configured.

In this case, it is possible to maintain the linear velocity even when the diameter is reduced by the use of the flaw forming roll member 20. In other words, since the rotational speeds of the rotating shafts connected to the upper diameter roll 23 and the lower diameter roll 24 are controlled, even if the diameters of the upper diameter roll 23 and the lower diameter roll 24 decrease due to wear, In order to maintain the linear speed, it is possible to maintain the linear speed by adjusting the rotation speed, such as increasing the rotation speed.

The flaw forming roll member 20 divided into the upper diameter roll 23 and the lower diameter roll 24 is provided in three sets, respectively, the first roll portion 20a, the second roll portion 20b, and the third. It is divided into a roll portion (20c).

Here, since the rotation speed v11 of the upper diameter roll 23 of the first roll portion 20a and the rotation speed v12 of the lower diameter roll 24 are different, a difference in linear speed occurs. In addition, since the rotation speed v21 of the upper diameter roll 23 of the second roll portion 20b and the rotation speed v22 of the lower diameter roll 24 are different, a difference in linear speed occurs, and the third roll portion 20c ), The rotation speed (v31) of the upper diameter roll (23) and the rotation speed (v32) of the lower diameter roll (24) are different.

In addition, the crack-forming roll member 20 of the crack forming unit 1 according to an embodiment of the present invention, each in pairs on the housing member 10 in order on the transport path of the steel sheet (S) It includes a first roll portion (20a), a second roll portion (20b) and a third roll portion (20c) provided, the first roll portion (20a) is rotated in the reverse direction to the transport direction of the steel sheet (S), the The third roll portion 20c may be characterized in that it is rotated in the forward direction in the conveying direction of the steel sheet (S).

That is, the first roll portion 20a, the second roll portion 20b, and the third roll portion 20c of the flaw forming roll member 20 can be adjusted to rotate in the reverse or forward direction with the traveling direction of the steel sheet S. In the reverse direction, the descaling effect is excellent, and in the case of forward rotation, a beautiful surface roughness can be obtained. In particular, the first roll portion 20a is rotated in the reverse direction to the conveying direction of the steel sheet S, The three-roll portion 20c is rotated in the forward direction in the conveying direction of the steel sheet S, so that it is possible to form an elegant surface roughness while increasing the efficiency of crack formation on the scale to increase the scale removal effect. This can be seen from the experimental data in Table 3 below.

In the experiment of Table 3, the abrasive of the abrasive slurry was a glass bead having a size of about 80 microns, the injection pressure was about 300 bar, and the injection angle was about 23 degrees. And, the upper roll of the first roll portion 20a maintains a linear speed of about 20 rpm, the lower roll maintains a linear speed of about 30 rpm, the upper roll of the second roll portion 20b is about 30 rpm, and the lower roll is about 20 rpm. The linear speed was maintained, and the upper roll of the third roll portion 20c maintained a linear speed of about 20 rpm and the lower roll of about 430 rpm.

division Rolling down rate (%) Roll drive direction
(F: forward, R: reverse) Residual scale (%) Illuminance (㎛) 1st roll part Second roll part Third roll part Top bottom Top bottom Top bottom Comparative Example 3-1 5 F F F F F F 10 0.7 Comparative Example 3-2 5 F F F F R R 3 3.5 Comparative Example 3-3 5 F F R R R R 1.0 4.3 Comparative Example 3-4 5 R R R R R R 0.5 4.8 Inventive Example 3-1 5 R R F F F F 1.0 1.0 Inventive Example 3-2 5 R R R R F F 0.5 1.2

4 is the crack forming unit 1 of the present invention, the defect forming roll member 20 is divided into a first roll portion 20a, a second roll portion 20b and a third roll portion 20c, and a second roll portion 20b ) As an example in which the horizontally biased arrangement is illustrated, referring to the drawings, the flaw forming roll member 20 of the crack forming unit 1 according to an embodiment of the present invention includes the steel sheet S ), The first roll portion 20a, the second roll portion 20b and the third roll portion 20c provided in pairs in the housing member 10 in order on the transport path, and the second roll portion ( 20b) may be characterized in that the first roll portion 20a and the third roll portion 20c are disposed with a bias toward the upper side or the lower side.

As described above, the flaw forming roll member 20 may be divided into a first roll portion 20a, a second roll portion 20b, and a third roll portion 20c. That is, the flaw forming roll member 20 is provided in three sets, each of which is divided into a first roll portion 20a, a second roll portion 20b and a third roll portion 20c, and for the steel sheet S In order to increase the efficiency of crack formation, the second roll portion 20b is disposed to be biased upward or downward on the line connecting the first roll portion 20a and the third roll portion 20c.

3 (a) is a case where the upper roll of the second roll portion 20b is larger than the lower roll and is disposed on the upper side, and in this case, the steel sheet S by the small diameter roll 21 having a small diameter ), Since the moving path of the band is bent, the steel sheet S is bent with a relatively small radius of curvature, so that when the scale is cracked, the pressing force is concentrated in a small area, so that the occurrence of cracks can be clarified.

Conversely, FIG. 3 (b) is a case in which the upper roll of the second roll portion 20b is disposed at a lower side when the diameter is larger than the lower roll, and in this case, the steel sheet by the large diameter roll 22 having a large diameter Since the movement path of (S) is bent, the steel plate S is bent with a relatively large radius of curvature, so that when the scale is cracked, the rolling force is dispersed in a large area, thereby inducing the formation of fine cracks.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to this, and it is possible in the art to make various modifications and variations without departing from the technical spirit of the present invention as set forth in the claims. It will be obvious to those with ordinary knowledge.

1: Crack forming unit 2: Spraying unit
3: Washing unit 4: Dry unit
5: Payoff reel 6: Tension reel
7: welding machine 10: housing member
20: flaw forming member 21: small diameter roll
22: large roll 23: upper roll
24: lower diameter roll

Claims (12)

delete delete delete A housing member disposed on the conveying path of the steel sheet; And
A pair of flaw forming roll members provided on the housing member, respectively contacting the upper and lower surfaces of the steel sheet, and having different linear velocities of the portions contacting the steel sheet;
Including,
The flaw forming roll member,
A first roll portion, a second roll portion, and a third roll portion provided in pairs on the housing member in order on the transport path of the steel plate;
It includes,
The second roll portion, a crack forming unit, characterized in that the different linear velocity ratios of the portions respectively contacting the upper and lower surfaces of the steel sheet are formed opposite to the linear velocity ratios of the first roll portion and the third roll portion. A housing member disposed on the conveying path of the steel sheet; And
A pair of flaw forming roll members provided on the housing member, respectively contacting the upper and lower surfaces of the steel sheet, and having different linear velocities of the portions contacting the steel sheet;
Including,
The flaw forming roll member,
A first roll portion, a second roll portion, and a third roll portion provided in pairs on the housing member in order on the transport path of the steel plate;
It includes,
The second roll portion, a crack forming unit, characterized in that the first roll portion and the third roll portion is disposed biased upward or downward on the line connecting the. A housing member disposed on the conveying path of the steel sheet; And
A pair of flaw forming roll members provided on the housing member, respectively contacting the upper and lower surfaces of the steel sheet, and having different linear velocities of the portions contacting the steel sheet;
Including,
The flaw forming roll member,
A first roll portion, a second roll portion, and a third roll portion provided in pairs on the housing member in order on the transport path of the steel plate;
It includes,
The first roll portion is rotated in the reverse direction to the conveying direction of the steel plate, the third roll portion is a crack forming unit, characterized in that rotated in the forward direction in the conveying direction of the steel plate. delete The crack forming unit of any one of claims 4 to 6; And
It is provided downstream of the transport path of the steel plate than the crack forming unit, the injection unit for spraying the abrasive slurry mixed with abrasives and high-pressure fluid to the steel plate;
Scale removing device comprising a. The method of claim 8,
A washing unit provided downstream of the conveying path of the steel plate than the spraying unit, and spraying washing water with the steel plate; And
A dry unit provided downstream of the conveying path of the steel plate than the washing unit, and spraying air to the steel plate;
Scale removing device comprising a. The method of claim 8,
The flaw forming roll member,
A small diameter roll contacting one surface of the steel sheet; And
A large diameter roll contacting the other surface of the steel sheet, rotating at the same rotational speed as the small diameter roll, and having a larger diameter than the small diameter roll;
Scale removing device comprising a. The method of claim 8,
The flaw forming roll member,
An upper diameter roll in contact with the upper surface of the steel sheet; And
A lower diameter roll which is in contact with the lower surface of the steel sheet, rotates at a different rotational speed from the upper diameter roll, and is formed with the same diameter as the upper diameter roll;
Scale removing device comprising a. The method of claim 8,
The flaw forming roll member, the scale removing device, characterized in that for reducing the steel sheet to a rolling reduction of 1 to 10%.

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