WO2019188503A1

WO2019188503A1 - Hot-dip galvanizing bath facility

Info

Publication number: WO2019188503A1
Application number: PCT/JP2019/011194
Authority: WO
Inventors: 祐輔入江; 川村　三喜夫; 功太郎大野; 晋平吉田
Original assignee: 日本製鉄株式会社
Priority date: 2018-03-26
Filing date: 2019-03-18
Publication date: 2019-10-03
Also published as: CN111406125A; JPWO2019188503A1; CN111406125B; JP6624348B1

Abstract

[Problem] To provide a hot-dip galvanizing bath facility having excellent bath substitution effect inside and outside a V-zone. [Solution] A straightening plate in a hot-dip galvanizing bath has a plurality of plate-shaped straightening pieces 12 disposed above a contact part Q of a sink roll 3 and an entry-side steel plate 5, which is a steel plate on an entry side of a hot-dip galvanizing bath 2, between a snout 6 and the sink roll 3. Each of the plate-shaped straightening pieces 12 forms an angle θ2 of 45° to 135° with the surface of the entry-side steel plate 5 and is disposed so that a cross section thereof parallel to the surface of the entry-side steel plate 5 forms an angle θ1 of more than 0° and less than 90° with respect to the plate width direction of the entry-side steel plate 5.

Description

Molten zinc bath equipment

The present invention relates to hot dip galvanizing equipment used in hot dip galvanizing lines for steel sheets.

The hot dip galvanizing equipment used in the hot dip galvanizing line for steel plates is provided with a sink roll and a support roll in the hot dip galvanizing bath. Then, the traveling direction is changed upward, and it is pulled up vertically from the molten zinc bath while being guided by the support roll, and during this time, the molten zinc adheres to the surface of the steel sheet.

In order to stabilize the quality of the galvanized steel sheet, it is necessary to strictly control the Al concentration in the molten zinc bath. For example, when the Al concentration is too high, poor alloying occurs, and when the Al concentration is too low, bottom dross is generated and accumulated in the bath and adheres to the steel sheet, thereby generating dross soot.

Currently, the Al concentration in the molten zinc bath is adjusted by introducing a small ingot of Zn—Al alloy from a specific location. However, since the region called the V zone surrounded by the steel plate on the sink roll in the molten zinc bath is surrounded by the steel plate, the substitution rate of the bath inside and outside the V zone is poor, and the bath tends to stay, And Al is consumed by steel plate passage, and Al concentration tends to become relatively low. Therefore, it can be said that the bottom dross that is the cause of dross trapping is easily generated and accumulated.

Therefore, increasing the amount of the small ingot of the Zn—Al alloy mentioned above so as not to cause dross soot leads to poor alloying. In order to eliminate the difference in Al concentration between the inside and outside of the V zone, if a small ingot of Zn—Al alloy is introduced into the V zone, an alloying failure may occur due to local concentration of Al, and the number of places to be added increases. This increases the workload of the operator.

Therefore, Patent Document 1 proposes a technique for arranging a rectifying plate in the V zone above the sink roll to promote bath replacement inside and outside the V zone. The current plate of Patent Document 1 is obtained by bending or curving a flat plate with a center line as a boundary, and the center line is disposed along the traveling direction of the steel sheet on the side entering the molten zinc bath. On the entrance side of the sink roll, the accompanying flow generated along the steel sheet traveling obliquely downward collides with the sink roll to become an upward zinc flow, but this zinc flow is applied to the current plate and directed outward in the sheet width direction of the steel sheet. It is intended to promote bath replacement inside and outside the V zone.

However, in this current plate, since the angle at which the upward zinc flow hits the current plate is shallow, the rectification action of directing the upward flow outward in the plate width direction is weak, and the Al concentration in the V zone is sufficiently lowered. It cannot be resolved. For this reason, there existed a problem that the effect which suppresses bottom dross was scarce.

Japanese Unexamined Patent Publication No. 2016-156077

Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to provide a molten zinc bath facility having an excellent bath replacement effect inside and outside the V zone.

The molten zinc bath facility of the present invention, which has been made to solve the above problems, is provided between the molten zinc bath and the inside of the molten zinc bath, between the snout and the sink roll, on the side entering the molten zinc bath. A molten zinc bath rectifying plate having a plurality of plate-like rectifying pieces disposed above the contact portion between the entry side steel plate and the sink roll, which is a steel plate, and each of the rectification pieces is on the surface of the entry side steel plate In contrast, an angle θ2 of 45 ° or more and 135 ° or less and a cross section parallel to the surface of the entry-side steel plate forms an angle θ1 of more than 0 ° and less than 90 ° with respect to the plate width direction of the entry-side steel plate. Are arranged as follows.

The angle θ2 is preferably 60 ° or more and 120 ° or less, and the angle θ1 is preferably 20 ° or more and 60 ° or less. The plurality of rectifying pieces are preferably symmetric with respect to the center of the sink roll in the cylinder length direction.

ADVANTAGE OF THE INVENTION According to this invention, the upward zinc flow generate | occur | produced by the collision with the accompanying flow of an entrance side steel plate, and the accompanying flow of a sink roll and a sink roll can be efficiently rectified, and can be converted into the outward flow of a steel plate width direction. Therefore, the bath replacement in the region surrounded by the steel plate on the sink roll called the V zone can be promoted, and the decrease in the Al concentration in this region can be prevented. As a result, the amount of bottom dross in the molten zinc bath can be reduced, and defects in the hot dip galvanized steel sheet due to the bottom dross can be suppressed.

It is a cross-sectional schematic diagram which shows the molten zinc bath equipment of 1st Embodiment. It is a top view which shows the principal part of the molten zinc bath equipment of 1st Embodiment. FIG. 3 is a view taken in the direction of arrows III-III in FIG. 1. It is the figure which looked at the molten zinc bath baffle plate and a part of steel plate from the IV-IV arrow direction of FIG. FIG. 5 is a view taken along arrow VV in FIG. 3. It is a figure explaining the structure of the molten zinc bath baffle plate of 1st Embodiment. It is a figure explaining the structure of the molten zinc bath baffle plate of 2nd Embodiment. It is a figure explaining the structure of the molten zinc bath baffle plate of 3rd Embodiment. It is a figure explaining the structure of the molten zinc bath baffle plate of 4th Embodiment. It is a figure explaining the structure of the molten zinc bath baffle plate of 5th Embodiment. It is a figure explaining the structure of the molten zinc bath baffle plate of 6th Embodiment.

Embodiments of the present invention will be described below. FIG. 1 is a schematic cross-sectional view showing a molten zinc bath facility of the first embodiment, FIG. 2 is a plan view showing an essential part thereof, and is a view taken along the line II-II in FIG. 1, and FIG. 4 is a view of a part of the molten zinc bath rectifying plate 8 and the steel plate 5 from the direction of arrows IV-IV in FIG. 3, and FIG. 5 is a view taken along arrows VV in FIG. In FIG. 1, 1 is a molten zinc bath, 2 is a molten zinc bath inside, 3 is a sink roll installed in the

molten zinc bath

2, and 4 is a support roll. The steel plate 5 enters the molten zinc bath 2 obliquely downward from the snout 6, turns upward around the lower surface of the sink roll 3, is guided by the support roll 4, and is pulled upward vertically. A region 7 called a V zone surrounded by the steel plate 5 is formed above the sink roll 3.

Hereafter, for the sake of explanation, an orthogonal coordinate system is set in the figure. An x axis is provided in the horizontal direction perpendicular to the axis 30 of the sink roll 3, and a y axis is provided in the vertical direction. The upper side in the vertical direction is the y-axis positive direction. A z-axis is provided in the horizontal direction along the axis 30 of the sink roll 3. Further, along the surface of the steel plate 5 on the side entering the molten zinc bath 2 (hereinafter also referred to as the entry side steel plate 5), an X axis is provided in parallel with the traveling direction of the entry side steel plate 5, and The direction opposite to the traveling direction is taken as the X-axis positive direction. A Y-axis orthogonal to the surface of the entry-side steel plate 5 is provided, and in a region 7 called a V zone surrounded by the steel plate 5, the side away from the surface of the entry-side steel plate 5 is defined as the Y-axis positive direction. A Z-axis is provided along the axis 30 of the sink roll 3.

The molten zinc bath 2 contains Al in addition to zinc. As described above, the Al concentration in the molten zinc bath 2 is adjusted by introducing a small ingot of a Zn—Al alloy from a specific location, but the V zone surrounded by the steel plate 5 above the sink roll 3. Since the region 7 called is surrounded by the steel plate 5 on both sides, the substitution rate of the bath 2 is poor, and the Al concentration is lowered and causes bottom dross. Therefore, in the present embodiment, the molten zinc bath rectifying plate 8 is disposed between the snout 6 and the sink roll 3 and above the contact portion Q between the entry-side steel plate 5 and the sink roll 3. In addition, the molten zinc bath baffle plate 8 can be supported inside the molten zinc tank 1 by, for example, a member connected to a gantry that supports the sink roll 3 and the like.

As shown in FIG. 1, in a region 7 called a V zone, an upward zinc flow 11 is generated due to a collision between the accompanying flow 9 of the approach-side steel plate 5 and the accompanying flow 10 accompanying the rotation of the sink roll 3. . The molten zinc bath rectifying plate 8 of the present embodiment is composed of a plurality of plate-like rectifying pieces 12, and the upward zinc flow 11 is rectified so as to face the outer side in the steel plate width direction, and the replacement rate of the bath 2. Has a role to enhance.

In the first embodiment shown in FIGS. 1 to 6, each plate-like rectifying piece 12 is formed of a rectangular flat plate having a width W and a length L, and the upper side (that is, the X-axis positive direction side) is the outer side in the steel plate width direction. It is arranged in a form that opens upward (that is, as it goes toward the X axis positive direction side). Here, the width W refers to the width of the plate-like rectifying piece 12 in a direction (Y-axis direction) orthogonal to the surface of the entry-side steel plate 5. The length L refers to the length of the plate-like rectifying piece 12 in the traveling direction of the entry-side steel plate 5 (X-axis direction which is the plate passing direction).

FIG. 6 is a view for explaining the structure of the molten zinc bath rectifying plate 8 of the first embodiment, in which each plate-like rectifying piece 12 is cut along a plane parallel to the surface of the entry-side steel plate 5, that is, each plate. The cross section parallel to the surface of the entrance side steel plate 5 of the rectifying piece 12 is shown. Each plate-like rectifying piece 12 is arranged symmetrically (that is, symmetrical in the Z-axis direction) with respect to the center in the trunk length direction (that is, the Z-axis direction) of the sink roll 3 indicated as CL. The plate-like rectifying pieces 12 are arranged at equal intervals with respect to the axis 30 (see FIGS. 1 and 3) of the sink roll 3 at an angle θ1 and a distance P1. The angle θ1 corresponds to an angle formed by a cross section of each plate-like rectifying piece 12 parallel to the surface of the entry-side steel plate 5 with respect to the plate width direction (Z-axis direction) of the entry-side steel plate 5. The interval P1 between the plate-like rectifying pieces 12 is a distance in the direction of the axis 30 (Z-axis direction) of the sink roll 3 between the two plate-like rectifying pieces 12 that are adjacent to each other and face each other. When counting the number N of the plate-like rectifying pieces 12, the plate-like rectifying pieces 12A in which two portions having an angle θ1 of more than 0 ° are connected are counted as two pieces. Therefore, the number N of the plate-like rectifying pieces 12 is 6.

Further, each plate-like rectifying piece 12 is arranged at an angle θ2 of 45 ° to 135 ° with respect to the surface of the entry-side steel plate 5 as shown in FIG. The value of θ2 is preferably 90 °, but it may be inclined with respect to the surface of the entry-side steel plate 5 in the range of ± 45 ° centering on 90 °. Each plate-like rectifying piece 12 is disposed so as to be inclined (in other words, to be opened) toward the outer side in the plate width direction of the approaching side steel plate 5 as it goes from the approaching side steel plate 5 side to the bath surface 20 side (in the positive y-axis direction). When the angle θ2 is set, the angle θ2 is smaller than 90 °. For example, the angle θ2 of the plate-like rectifying piece 12 inclined 30 ° outward in the plate width direction with respect to the normal line of the entry-side steel plate 5 is 60 °. On the other hand, when each plate-like rectifying piece 12 is disposed so as to tilt toward the inner side in the plate width direction of the approaching side steel plate 5 from the approaching side steel plate 5 side toward the bath surface 20 (in other words, to close in other words), the angle θ2 is greater than 90 °. For example, the angle θ2 of the plate-like rectifying piece 12 inclined by 30 ° inward in the plate width direction with respect to the normal line of the entry-side steel plate 5 is 120 °.

Hereinafter, second to sixth embodiments of the structure of the molten zinc bath rectifying plate 8 will be described. When the molten zinc bath rectifying plate 8 of the second to sixth embodiments is viewed from the direction of the axis 30 of the sink roll 3 (Z-axis direction), it is as shown in FIG. 5 as in the first embodiment. As in the second embodiment shown in FIG. 7, each plate-like rectifying piece 12 is curved with a radius of curvature R that is curved so as to swell on the opposite side (X-axis positive direction side) of the entry-side steel plate 5. It is a face plate, and may be symmetrically arranged at equal intervals. Further, as in the third embodiment shown in FIG. 8, each plate-like rectifying piece 12 may be a curved plate curved in the opposite direction to FIG. 7 (that is, so as to swell in the negative direction of the X axis). . In any case, in each plate-like rectifying piece 12, the interval between the upper portions (X-axis positive direction ends) and the lower portion (X-axis negative direction ends) are equal. Further, as shown in FIGS. 7 and 8, the angle θ1 is such that a virtual straight line connecting the longitudinal ends of the cross section of each plate-like rectifying piece 12 is in the plate width direction (Z-axis direction) of the entry-side steel plate 5. It can be calculated as an angle formed with respect to it.

Further, in the fourth embodiment shown in FIG. 9, each plate-like rectifying piece 12 is made of a rectangular flat plate, and is arranged at equal intervals, but is asymmetrical in the left-right direction. In other words, the center of the plurality of plate-like rectifying pieces 12 (specifically, the apex 120 of the plate-like rectifying pieces 12A) in the direction of the axis 30 (Z-axis direction) of the sink roll 3 is the trunk length direction of the sink roll 3 It is offset by a distance D with respect to the center CL. Further, in the fifth embodiment shown in FIG. 10, the plate-like rectifying pieces 12 are made of rectangular flat plates, are inclined in the same direction, and are arranged at equal intervals. Further, in the sixth embodiment shown in FIG. 11, each plate-like rectifying piece 12 is made of a rectangular flat plate and is symmetric, but is arranged at unequal intervals P1 and P2. When the arrangement of the plurality of plate-like rectifying pieces 12 is different at any position in the direction of the axis 30 (Z-axis direction) of the sink roll 3 (for example, a plurality of plate-like rectifying pieces with respect to the above position) 12 is symmetrically arranged), the interval between the plate-like rectifying pieces 12 (for example, two flat plates constituting the plate-like rectifying piece 12A) facing each other across the position is not considered as the intervals P1 and P2.

As shown in these embodiments, the arrangement of the plate-like rectifying pieces 12 can be variously changed in addition to the first embodiment. In these embodiments, the angle θ1 or the angle θ2 may not be the same value between the plate-like rectifying pieces 12. In other words, the adjacent plate-like rectifying pieces 12 may not be parallel to each other. Further, the plate-like rectifying pieces 12A in which the portions on both sides are connected to each other with the apex 120 interposed therebetween may be separated from each other on both sides. Furthermore, the number N of the plate-like rectifying pieces 12 may be plural (two or more), and is not limited to 6, and may be 4, 5, 7, 8, or the like.

If the molten zinc bath rectifying plate 8 configured in this way is arranged in a region 7 called a V zone, it is generated by the collision between the accompanying flow 9 of the approach-side steel plate 5 and the sink roll 3 and the accompanying flow 10 of the sink roll 3. The upward zinc flow 11 can be efficiently rectified by the plate-like rectifying pieces 12 to the outside in the steel plate width direction. In addition, the installation range of the molten zinc bath rectifying plate 8 in the region 7 may be a range in which the upward zinc flow 11 hits at least a part of each plate-like rectifying piece 12. As surrounded by a one-dot chain line in FIG. 1, within a predetermined range (for example, within 1000 mm) upward from the contact portion Q between the approach side steel plate 5 and the sink roll 3 (for example, within 1000 mm), from the contact portion Q to the snout 6 In the horizontal direction (x-axis positive direction) within a predetermined range (for example, within 500 mm) and from the center in the plate width direction of the steel plate 5 (or the center CL in the trunk length direction of the sink roll 3) to the plate width direction (z axis) At least a part of each plate-like rectifying piece 12 may be arranged within a predetermined range (for example, within ± 1000 mm) in the direction).

In particular, each plate-like rectifying piece 12 is arranged at an angle θ2 of 45 ° or more and 135 ° or less with respect to the surface of the entry-side steel plate 5, and on the surface of the entry-side steel plate 5 of each plate-like rectification piece 12. By arranging the parallel cross section at an angle θ1 of more than 0 ° and less than 90 ° with respect to the plate width direction of the entry side steel plate 5, the center line of the straightening or bending of the rectifying plate is along the traveling direction of the entry side steel plate. Thus, the upward zinc flow 11 can be applied to each plate-like rectifying piece 12 at a larger angle than the conventional rectifying plate arranged in this manner, and the replacement rate of the bath 2 can be increased as compared with the conventional rectifying plate. As a result, a decrease in the Al concentration in the region 7 called the V zone can be prevented, and defects in the hot dip galvanized steel sheet due to bottom dross can be suppressed. According to the results of the applicant company, the amount of bottom dross was reduced to less than half of the conventional amount. Examples of the above embodiments will be described below.

The plate-shaped rectifying piece 12 is changed in size W, L, angle θ1, curvature radius R, number N, intervals P1, P2, center offset D, angle θ2, and the replacement rate η of the bath 2 is changed to FULL (CFD simulation software). ) Was used for numerical calculation. Here, the substitution rate η is a ratio of the volume of the bath 2 newly introduced after passing the steel plate 5 for 2 minutes to the volume of the bath 2 before passing the steel plate 5 in the region 7 called V zone. . In addition, the plate speed of the steel plate 5 was 120 m / min, and the plate width was 1600 mm. The results are shown in Table 1.

As shown in Table 1, in Comparative Example 1 without the molten zinc bath rectifying plate 8, the substitution rate η of the bath 2 was 31%. However, according to each example, the substitution rate η was 41 to 88%. Was able to greatly increase. In the simulation, the substitution rate η can be increased to 95%.

Comparative Example 2 is similar to the rectifying plate described in FIG. 2 of the above Japanese Patent Application Laid-Open No. 2016-1556077, and the flat plate is bent around its center line, and this center line is along the traveling direction of the entry side steel plate 5. The angle θ2 is 20 ° (that is, less than 45 °), and the angle θ1 is 90 °. In Comparative Example 2, the substitution rate η was as small as 36%. This is because the angle at which the upward zinc flow 11 hits the plate-like rectifying piece 12 is shallow, and thus the rectification action of directing the upward zinc flow 11 outward in the plate width direction of the steel plate 5 is weak, and Al in the region 7 called the V zone This is probably because the decrease in density cannot be sufficiently eliminated.

The substitution rate η of Comparative Example 4 in which the angle θ2 is 150 ° (ie, more than 135 °) and the substitution rate η of Comparative Example 5 in which the angle θ2 is 30 ° (ie, less than 45 °) are both 39% and small. It was. On the other hand, the substitution rate η of Example 24 in which the angle θ2 is 135 ° and the substitution rate η in Example 26 in which the angle θ2 is 45 ° are both 50% and large. Thus, it can be seen that the replacement of the bath 2 in the region 7 called the V zone can be promoted by setting the angle θ2 to 45 ° or more and 135 ° or less. This is because when the angle θ2 is outside the range of 45 ° to 135 °, the upward zinc flow 11 shown in FIGS. However, when the value of the angle θ2 is within the range of 45 ° to 135 °, the upward zinc flow 11 is efficiently rectified to efficiently rectify the steel plate 5 toward the outside in the plate width direction. This is thought to be because it can be converted into a flow that faces outward.

The substitution rate η when the angle θ2 was 60 ° (66% of Example 25) was larger than the substitution rate η when the angle θ2 was 45 ° (50% of Example 26). The substitution rate η (66% of Example 23) when the angle θ2 was 120 ° was larger than the substitution rate η (50% of Example 24) when the angle θ2 was 135 °. The substitution rate η was maximized when the angle θ2 was 90 ° (77% of Example 21). When the angle θ2 is 60 ° to 90 °, the increase rate of the substitution rate η with respect to the increase of the angle θ2 is smaller than when the angle θ2 is 45 ° to 60 °. When the angle θ2 is 90 ° to 120 °, the increase rate of the substitution rate η with respect to the decrease of the angle θ2 is smaller than when the angle θ2 is 120 ° to 135 °. Thus, it was found that by setting the angle θ2 to 60 ° or more and 120 ° or less, a large substitution rate η can be stably obtained.

The substitution rate η of Comparative Example 2 where the angle θ1 is 90 ° was as small as 36%. This is considered to be because it is difficult for the upward zinc flow 11 to hit the plate-like rectifying piece 12 when viewed in the direction along the surface of the entry-side steel plate 5. Moreover, the substitution rate η of Comparative Example 3 in which the angle θ1 was 0 ° was as small as 32%. This is because the upward zinc flow 11 hits the plate-like rectifying piece 12 in a direction perpendicular to the surface of the entry-side steel plate 5 so that the zinc flow 11 is directed to the outside in the plate width direction of the steel plate 5. This is thought to be because the action is rather weakened. On the other hand, the substitution rate η of Example 22 in which the angle θ1 is 45 ° was as large as 53%. Thus, it can be seen that the replacement of the bath 2 in the region 7 called the V zone can be promoted by setting the angle θ1 within the range of more than 0 ° and less than 90 °. This is considered to be because, when viewed in the direction along the surface of the entry-side steel plate 5, it is possible to efficiently generate a rectification action that directs the upward zinc flow 11 toward the outside in the plate width direction of the steel plate 5.

The substitution rate η (59% of Example 9) when the angle θ1 is 20 ° was larger than the substitution rate η (41% of Example 8) when the angle θ1 was 10 °. The substitution rate η (55% of Example 13) when the angle θ1 was 60 ° was larger than the substitution rate η (45% of Example 14) when the angle θ1 was 70 °. When the angle θ1 was 30 °, the substitution rate η was maximized (75% of Example 11). When the angle θ1 was 20 ° to 30 °, the increase rate of the substitution rate η relative to the increase of the angle θ1 was smaller than when the angle θ1 was 10 ° to 20 °. The increase rate of the substitution rate η with respect to the decrease of the angle θ1 was smaller when the angle θ1 was 30 ° to 60 ° than when the angle θ1 was 60 ° to 70 °.

Thus, it was found that a large substitution rate η can be stably obtained by setting the angle θ1 to 20 ° or more and 60 ° or less. This means that by setting the lower limit value of the angle θ1 to 20 °, the angle at which the upward zinc flow 11 hits the plate-like rectifying piece 12 becomes too large when viewed in the direction along the surface of the entry-side steel plate 5. This is not only because the rectifying action can be secured by suppressing, but also because the cross-sectional area between the plurality of plate-like rectifying pieces 12 can be restrained and the flow path cross-sectional area between them can be secured to some extent. . Further, by setting the upper limit value of the angle θ1 to 60 °, when viewed in the direction along the surface of the entry-side steel plate 5, a certain amount of the upward zinc flow 11 hits the plate-like rectifying piece 12 is ensured to some extent. This is considered to be because the zinc flow 11 can be directed outward in the plate width direction of the steel plate 5. Furthermore, it was found that the substitution rate η of 70% or more can be stably obtained by setting the angle θ1 to 25 ° or more and 40 ° or less (70% of Example 10 and 72% of Example 12). . This is thought to be because the above action can be obtained more effectively.

The replacement rate η of Comparative Example 3 in which the number N of the plate-like rectifying pieces 12 is 1 was as small as 32%. On the other hand, the replacement rate η of Example 22 in which the number N of the plate-like rectifying pieces 12 is 2 was as large as 53%. Therefore, it was found that a large substitution rate η can be obtained by setting the number N of the plate-like rectifying pieces 12 to 2 or more.

When the number N of plate-like rectifying pieces 12 is 2, the replacement rate η is 66% (Example 15), and when the number N is 4, the replacement rate η is 75% (Example 11). When the number N is 6, the substitution rate η is 85% (Example 16), and when the number N is 8, the substitution rate η is 88% (Example 17). Therefore, it was found that when the number N is 4 or more, a large substitution rate η of 75% or more can be obtained. It was also found that the greater the number N, the greater the obtained substitution rate η. However, when the number N is too large, there is a high possibility that the plate-like rectifying pieces 12 interfere with each other due to space limitations in the facility. From this viewpoint, it can be said that the upper limit of N is preferably 6 to 8, for example.

The substitution rate η (59% of Example 2) when the width W of the plate-like rectifying piece 12 was 150 mm was larger than the substitution rate η (50% of Example 1) when the width W was 50 mm. . The substitution rate η (63% of Example 3) when the width W was 250 mm was larger than the substitution rate η (59% of Example 2) when the width W was 150 mm. The substitution rate η (63% of Example 4) when the width W was 350 mm was the same as the substitution rate η (63% of Example 3) when the width W was 250 mm.

It was found that a large substitution rate η can be stably obtained by setting the width W to 50 mm or more. If the width W is too small, the upward zinc flow 11 is less likely to hit the plate-like rectifying piece 12, and the rectification action that directs the upward zinc flow 11 toward the outside in the plate width direction of the steel plate 5 is considered to be weak. By setting the lower limit of the width W to 50 mm, a certain amount of the upward zinc flow 11 hits the plate-like rectifying piece 12 can be secured to the outside in the plate width direction of the steel plate 5. On the other hand, if the width W is too large, the plate-like rectifying piece 12 approaches the steel plate 5 in the region 7 called the V zone, so that the possibility of interference between the plate-like rectifying piece 12 and the steel plate 5 increases. By setting the upper limit of the width W to, for example, 250 mm, interference between the plate-like rectifying piece 12 and the steel plate 5 can be suppressed while obtaining a large substitution rate η.

The substitution rate η (63% of Example 3) when the length L of the plate-like rectifying piece 12 is 200 mm is larger than the substitution rate η (61% of Example 5) when the length L is 100 mm. It was a little big. The substitution rate η (63% of Example 6) when the length L was 300 mm was slightly larger than the substitution rate η (60% of Example 7) when the length L was 400 mm. Thus, it was found that a large substitution rate η can be stably obtained by setting the length L to 100 mm or more. It was also found that a large substitution rate η can be obtained more stably by setting the length L to 200 to 300 mm.

The substitution rate η (70%) of Example 28 which is an example of the third embodiment shown in FIG. 8 is the substitution rate η (61%) of Example 27 which is an example of the second embodiment shown in FIG. It was bigger than. This is because, in the second embodiment (FIG. 7), the flow path cross-sectional area between adjacent plate-like rectifying pieces 12 is more on the outlet side (X-axis positive direction) than on the inlet side (X-axis negative direction side) of the flow path. On the other hand, in the third embodiment (FIG. 8), the flow path cross-sectional area is smaller on the outlet side (X-axis positive direction) than on the inlet side (X-axis negative direction side) of the flow path. It is considered that the upward zinc flow 11 can flow more smoothly along the plate-like rectifying piece 12 by becoming larger on the side).

The substitution rate η (75% of Example 11) when the interval P1 between the plate-like rectifying pieces 12 is 300 mm is the substitution rate η (70% of Example 18) and the interval P1 when the interval P1 is 200 mm. Was slightly larger than the substitution rate η (72% of Example 19) when 400 mm. Thus, it was found that a large substitution rate η can be stably obtained by setting the interval P1 to 200 to 400 mm. It was also found that a large substitution rate η can be obtained more stably by setting the interval P1 to 300 mm or in the vicinity thereof.

The substitution rate η (75% of Example 20 and 77% of Example 21) when the spacing between the plate-like rectifying pieces 12 is the same is the substitution rate η (72% of Example 31) when the spacing is different. ). Therefore, it may be advantageous that the intervals are the same, but even if the intervals are somewhat different, the influence on the substitution rate η is considered to be small.

The substitution rate η (77% of Example 21) when the plate-like rectifying pieces 12 are arranged symmetrically with respect to the body length direction center CL of the sink roll is that the plate-like rectifying pieces 12 are arranged asymmetrically. It was larger than the substitution rate η (63% of Example 29). Thus, it was found that a larger replacement rate η can be obtained by arranging the plate-like rectifying pieces 12 symmetrically with respect to the center length CL of the sink roll. Moreover, when each plate-shaped rectification piece 12 is arrange | positioned symmetrically, since it suppresses that the upward zinc flow 11 is biased to the one side of the plate width direction of the steel plate 5, it suppresses that a pattern defect arises in the steel plate 5. It is considered possible.

The substitution rate η (77% of Example 21) when each plate-like rectifying piece 12 is arranged in a different direction is the same as when each plate-like rectifying piece 12 is arranged in the same direction. Was greater than the substitution rate η (66% of Example 30). Thus, it has been found that a larger replacement rate η can be obtained by arranging the plate-like rectifying pieces 12 to be inclined in different directions. Further, since each plate-like rectifying piece 12 is arranged to be inclined in a different direction, it is possible to suppress the upward zinc flow 11 from being biased to one side in the plate width direction of the steel plate 5. It is thought that it can suppress that this occurs.

DESCRIPTION OF SYMBOLS 1 Molten zinc tank 2 Molten zinc bath 3 Sink roll 4 Support roll 5 Steel plate 6 Snout 7 Area called V zone 8 Molten zinc bath current plate 9 The accompanying flow 10 of a steel plate The accompanying flow 11 of a sink roll 12 Zinc flow 12 Fragment

Claims

A molten zinc bath;
Inside the molten zinc bath, a plurality of disposed between the snout and the sink roll and above the contact portion between the entrance side steel plate and the sink roll, which is a steel plate on the side entering the molten zinc bath. A molten zinc bath rectifying plate having a plate-like rectifying piece of
Each of the rectifying pieces has an angle θ2 of 45 ° or more and 135 ° or less with respect to the surface of the entry-side steel plate, and a cross section parallel to the surface of the entry-side steel plate has a plate width of the entry-side steel plate. Arranged to form an angle θ1 of more than 0 ° and less than 90 ° with respect to the direction,
Molten zinc bath equipment.
The molten zinc bath facility according to claim 1, wherein the angle θ2 is not less than 60 ° and not more than 120 °.
The molten zinc bath facility according to claim 1 or 2, wherein the angle θ1 is not less than 20 ° and not more than 60 °.
The molten zinc bath facility according to any one of claims 1 to 3, wherein the plurality of rectifying pieces are symmetrical with respect to a center in a cylinder length direction of the sink roll.