CN101821420B - Apparatus for producing molten metal plated steel strip and process for producing molten metal plated steel strip - Google Patents

Abstract

A hot-dip metal strip manufacturing device is provided, in which gas is sprayed from a gas wiping nozzle (3) to the surface of a steel strip (S) continuously pulled up from a hot-dip metal bath (8) to coat the surface of the steel strip For the control of the amount of adhesion, on both sides of the steel strip (S) under the liquid surface of the molten metal tank (9), there are molten metal throttling parts (1, 1), and a shield (2) is provided between the above-mentioned molten metal throttling members (1, 1) disposed opposite to the steel strip (S) on the extension line of the steel strip surface. With this device, excess molten metal attached to the steel sheet pulled up from the coating bath can be reduced within the entire width of the steel strip even if the steel strip width is changed, thereby reducing the generation of spatter in the gas wiping process.

Description

Hot-dip metal strip manufacturing device and hot-dip metal strip manufacturing method

technical field

The present invention relates to a manufacturing device of a hot-dip metallized steel strip capable of reducing spatter of molten metal in a hot-dip metallization process, and a method of manufacturing a hot-dip metallized steel strip using the device.

Background technique

A general continuous hot-dipping device and process will be described using FIG. 7 . The following gas wiping device is provided: the steel strip S is immersed in the hot-dip metal bath 8 in the molten metal bath 9, the direction is changed by the guide roller 7, and the steel strip S is pulled up vertically. Afterwards, pressurized gas is sprayed on the steel strip from the gas wiping nozzle 3 extending in the width direction of the steel strip, which clamps the steel strip S and is arranged oppositely, so as to remove excess molten metal and control the adhesion amount of the molten metal (coating adhesion amount). ), so that the molten metal attached to the surface of the steel strip uniformly reaches the predetermined coating thickness in the direction of the width of the strip and the direction of the length of the strip.

In order to stabilize the moving position of the steel strip in the gas wiping section, usually, the in-bath backup roll 5 is placed under the bath surface above the guide roll 7. In addition, when performing alloying treatment, etc., a bath top is installed above the gas wiping nozzle 3 if necessary. Backup roller 4.

The gas wiping nozzle 3 is usually longer than the width of the steel strip, that is, extends to the outside of the width end of the steel strip S in order to adapt to various steel strip widths and cope with the deviation in the width direction when the steel strip is pulled up. In such a gas wiping device, since the jet flow hitting the steel strip S is disturbed, the molten metal falling below the steel strip scatters around to generate so-called spatter, which degrades the surface quality of the steel strip.

In addition, in the continuous process, in order to increase the output, the passing speed of the steel strip can be increased, but when the gas wiping method is used to control the coating adhesion in the continuous hot-dip process, due to the viscosity of the molten metal, as the production line speed increases, , the initial adhesion of the steel strip just after passing through the coating bath increases, so in order to control the coating adhesion within a certain range, the pressure of the wiping gas has to be set to a higher pressure, thus, the spatter increases greatly and becomes Unable to maintain good surface quality.

In order to solve the above-mentioned problems, there is disclosed a method of reducing the excess molten metal attached to the steel strip to a certain extent before reaching the wiping nozzle, thereby reducing the initial deposition amount immediately after passing through the coating bath.

Japanese Patent Laying-Open No. 2004-76082 discloses the following device, which is provided with non-contacting molten metal throttling parts on both sides of the steel strip between the back-up roll 5 and the wiping nozzle 3 in the plating solution to remove excess coating, and then adjust the thickness of the coating by gas wiping, the shape of the molten metal throttling part is preferably a rectangle, the shape of the introduction part or a cylinder with a larger distance between the lower end and the inner and outer surfaces of the steel strip, the molten metal throttling The installation position of the component is most preferably a position straddling the upper and lower sides of the plating solution surface. In addition, it is preferable that the molten metal throttling member is installed so as to surround the steel strip.

However, in this method, even though the excessive molten metal in the central part in the width direction of the steel strip can be throttled by the molten metal throttling member, at both ends in the width direction of the steel strip, due to the molten metal flowing from the outer side of the steel strip to the steel Since the central portion in the width direction of the strip flows in, the throttling effect of the molten metal decreases at both ends in the width direction of the steel strip. Therefore, it can be seen that the difference in the amount of excess molten metal between the central part and both ends in the width direction is larger than that without the above-mentioned molten metal throttling member, and the effect of reducing spatter in the subsequent gas wiping process is reduced. In addition, since the shape surrounding the steel strip disclosed in this method cannot cope with changes in the width of the produced steel strip, the strip width dimension that can exhibit the throttling effect of the molten metal is limited.

The present invention takes the above problems into consideration, and provides hot-dip metal strip manufacturing equipment capable of reducing excess molten metal attached to the steel sheet pulled up from the coating bath within the range of the overall width of the strip even if the strip width is changed, thereby The generation of spatter in the gas wiping process can be reduced, and a hot-dip metal strip with excellent surface appearance can be stably produced.

Furthermore, the present invention provides a steel strip manufacturing method capable of reducing the generation of spatter in the gas wiping process and capable of stably manufacturing a hot-dip metallized steel strip with excellent surface appearance.

Contents of the invention

The present invention provides (1) a hot-dip metal strip manufacturing device, which sprays gas from the gas wiping nozzle to the steel strip surface continuously pulled up from the hot-dip metal bath to control the coating adhesion amount on the steel strip surface , it is characterized in that, on both sides of the steel strip under the liquid surface of the molten metal tank, there are molten metal throttling parts arranged opposite to the steel strip with a length greater than the width of the steel strip, and the said Shields are arranged between the molten metal throttling parts arranged opposite to the steel belt.

And, provide (2) the hot-dip metal strip manufacturing device as described in (1), it is characterized in that, the length of the steel strip facing surface of the shield in the steel strip advancing direction is that the steel strip of the molten metal throttling member faces The surface is more than 50% of the length of the steel strip advancing direction (when the length of the steel strip facing surface of the molten metal throttling part in the steel strip advancing direction is different on both sides of the steel strip, it is the steel strip facing surface of the molten metal throttling part The steel strip facing surface of the molten metal throttling member with a small length in the steel strip advancing direction is more than 50% of the length in the steel strip advancing direction), and the distance between the molten metal throttling member and the shield is 3mm or less.

Furthermore, there is provided (3) a method for manufacturing a hot-dip metal strip, wherein the hot-dip metal strip is hot-dipped using the manufacturing apparatus for a hot-dip steel strip according to (1) or (2).

Description of drawings

FIG. 1 is a cross-sectional view showing an embodiment of a hot-dip metal strip manufacturing apparatus according to the present invention.

Fig. 2(a) and Fig. 2(b) are diagrams illustrating the functions of the molten metal throttling member and the shield in the hot-dip metal strip manufacturing apparatus of the present invention.

Fig. 3 is a first diagram illustrating a combination example of cross-sectional shapes of a molten metal throttling member and a shield used in the hot-dip metal strip manufacturing apparatus of the present invention.

4( a ) and FIG. 4( b ) are second diagrams illustrating a combination example of the cross-sectional shape of the molten metal throttling member and the cross-sectional shape of the shield provided in the hot-dip metal strip manufacturing apparatus of the present invention.

5( a ) and FIG. 5( b ) are third diagrams illustrating a combination example of the cross-sectional shape of the molten metal throttling member and the cross-sectional shape of the shield provided in the hot-dip metal strip manufacturing apparatus of the present invention.

6(a) and 6(b) are fourth diagrams illustrating a combination example of the cross-sectional shape of the molten metal throttling member and the cross-sectional shape of the shield provided in the hot-dip metal strip manufacturing apparatus of the present invention.

Fig. 7 is a cross-sectional view showing a general hot-dip metal strip manufacturing apparatus.

Detailed ways

If a molten metal throttling member for removing excess molten metal is installed between the guide roll and the gas wiping nozzle, the molten metal removed by gas wiping will flow down and form a gap between the steel strip and the molten metal throttling member. Liquid storage place. If the distance from the liquid storage place to the gas wiping part is short, the excessive amount of molten metal cannot be reduced, so the present inventors have come to the conclusion that it is better to arrange the molten metal throttling member below the plating solution surface.

However, only the molten metal throttling parts are provided, and the throttling effect of the molten metal at both ends of the steel strip is still relatively small. Therefore, in order to effectively reduce the amount of molten metal attached to the steel strip taken out of the coating bath, detailed flow analysis was performed using a water model device that simulates the flow of molten metal around the molten metal throttling member. As a result, it was found that in order to reduce the amount of molten metal lifted out of the coating bath along with the steel strip, it is effective to suppress the flow from both ends of the steel strip to the center of the steel strip.

The present inventors have accomplished the present invention based on the above findings.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following figures, the same symbols are given to the same parts as those shown in the already described figures, and their descriptions will be omitted.

FIG. 1 is a cross-sectional view showing an embodiment of a hot-dip metal strip manufacturing apparatus according to the present invention. In Fig. 1, 1 is a molten metal throttling part set in the coating bath, which clamps the steel strip S above the back-up roll 5 in the bath, and is set on both sides of the steel strip at a predetermined distance from the surface of the steel strip. 2 is a shield, which is provided near the end of the steel strip S between the molten metal throttling members 1 and 1 disposed opposite to the steel strip S on the extension line of the steel strip surface. "On the strip surface extension line" means a line parallel to the width direction of the steel strip. In addition, the "shield" is a member that shields the plating solution and suppresses the flow of the plating solution from both ends of the steel strip to the center of the steel strip.

Fig. 2 (a) and Fig. 2 (b) are the figures that explain the effect of the molten metal throttling member of the device of the present invention and the shield, and Fig. 2 (a) shows that when only having the molten metal throttling member, it is throttled by the molten metal A plan view of the flow of molten metal at the end of the steel strip in the area sandwiched by the parts. Figure 2(b) shows the end of the steel strip in the area sandwiched by the molten metal throttling member when the molten metal throttling member and the shield 2 are provided. A top view of the flow of molten metal in a section. Regardless of the shape of the molten metal throttling member 1 , if only the molten metal throttling member 1 is provided, a flow 11 of molten metal from the end portion of the steel strip to the central portion of the steel strip occurs as shown in FIG. 2( a ). The larger the plating throttling effect by the molten metal throttling member 1 is, the more the flow 11 of the molten metal tends to increase as compensation. Therefore, the throttling effect of the molten metal throttling member 1 weakens or disappears at both ends of the steel strip. As shown in Figure 2 (b), if the shield 2 is arranged between the above-mentioned molten metal throttling parts 1 and 1 arranged opposite to the steel strip on the extension line of the steel strip surface, it can shield the molten metal from the steel strip end. Therefore, the excessive molten metal throttling effect produced by the molten metal throttling member 1 can be uniformly displayed within the entire width of the steel strip.

Even if the width of the steel strip is changed, the coating thickness can still be adjusted through the gas wiping nozzle after the molten metal throttling parts and shields are used to reduce the excessive amount of molten metal attached to the steel strip within the total width of the steel strip, so it can be greatly improved. Reduce the amount of spatter generated. According to the present invention, since the throttling effect of molten metal can be exhibited even when the passing speed of the steel strip is greatly increased, the amount of spatter generated can be greatly reduced, and thus a hot-dip metal strip without surface defects can be manufactured with high productivity.

The steel strip side end surface of the shield 2 is preferably perpendicular to the steel strip surface as shown in FIG. 2( b ). The distance between the steel strip end and the steel strip-side end surface of the shield 2 may be 5 mm or less, and the smaller the distance, the more preferable. In addition, in a state where the pressing force on the steel strip does not act, it is the most preferable condition that the steel strip end is in contact with the steel strip-side end surface of the shield 2 .

The gap between the molten metal throttling member 1 and the shield 2 is preferably 3 mm or less, and the smaller the gap, the better.

From the viewpoint of preventing the molten metal between the molten metal throttling parts 1 and 1 from flowing toward the center of the steel strip, the length (length in the vertical direction) of the steel strip facing surface of the shield 2 in the steel sheet advancing direction is preferably at least as large as the molten metal throttling part. 1 is 50% or more of the length in the steel plate advancing direction, most preferably the same length as the molten metal throttling member 1.

When the distance between the steel strip facing surface of the molten metal throttling member 1 and the steel strip changes in the steel strip advancing direction, the gap between the molten metal throttling member 1 and the shield 2 in the steel strip advancing direction is preferably kept as constant as possible. For example, as shown in Figure 3, when the cross-sectional shape of the molten metal throttling member 1 is circular, the surface of the shield 2 facing the molten metal throttling member 1 is preferably composed of the following concave arc surface: The radius of curvature of the arc of the throttling member 1 is slightly larger.

The cross-sectional shape of the molten metal throttling member is not limited to the shape of FIG. 3 . Various shapes as described below may be employed. For example, as shown in Figure 4 (a), the cross-sectional shape is triangular, and the surface opposite to the steel strip S and the upper surface opposite to the bath surface are parallel to the steel strip S and the bath surface respectively, then the molten metal joint can be further improved. Throttling performance of flow member 1. If the cross-sectional shape of the molten metal throttling member 1 is made into such a shape, even if a flow (wake flow) 11 accompanying the advancement of the steel strip S occurs, the fluid will easily flow in a direction with less resistance, so the molten metal throttling member The lower part of 1 exits the flow 13, which plays a role in hindering the growth of the accompanying flow 11. Furthermore, since the flow 13 flows in a direction away from the steel strip S, it becomes opposed to the flow 12 flowing toward the steel strip S above the molten metal throttling member 1 , and also has the effect of reducing the velocity of the flow 12 . The flow control of the molten metal throttling member 1 as described above can significantly suppress the wake flow around the steel strip S lifted from the coating bath, thereby reducing the amount of excess hot-dip metal attached to the steel strip S. As a result, the pressure of the wiping gas can be lowered, the amount of spatter of molten metal can be reduced, and a coated steel strip with good surface quality can be produced. In this case, as shown in FIG. 4( b ), the cross-sectional shape of the shield 2 may be a rectangle.

The cross-sectional shape of the molten metal throttling part 1 of Fig. 5 (a), the cross-sectional curve of its upper surface and the cross-sectional curve of the lower surface are all convex arc shapes on the steel strip pull-up part side of the hot-dip metal bath, and above The radius of curvature of the arc on the surface is smaller than the radius of curvature of the arc on the lower surface. Furthermore, the thickness of the molten metal throttling member 1 gradually decreases toward the end portion on the side opposite to the steel strip and the end portion on the side opposite to the bath surface. The shape of the molten metal throttling member 1 most notably exhibits the effect of branching the wake 11 into the flow 13 and the effect of forming convection to the flow 12 .

At this time, as shown in FIG. It is composed of a concave arc surface with a large curvature radius, and it is preferable to keep the distance between the molten metal throttling member 1 and the shield 2 as constant as possible.

The molten metal throttling members 1a and 1b shown in FIG. 6(a) have a roll covering portion formed so as to cover the bath surface side of the outer peripheral surface of the back-up roll 5 in the bath, and a roller covering portion arranged above the roll covering portion. The opposite part of the steel strip formed by the way that the steel strip faces each other. The in-bath backup rolls 5 run on both sides of the steel strip so as to be in contact with the steel strip, and are arranged so that their positions in the vertical direction are different from each other. Therefore, the lengths of the molten metal restricting members 1a and 1b arranged on both sides of the steel strip S facing the steel strip in the direction in which the steel strip advances differ from each other. The steel strip facing parts of the molten metal throttling members 1a, 1b may be parallel or inclined with respect to the steel strip surface.

Due to the molten metal throttle members 1a, 1b, a flow 14 accompanying the in-bath backup roll 5 is generated between the in-bath backup roll 5 and the molten metal throttle members 1a, 1b. If the flow 14 occurs, even if the wake 15 accompanying the advancement of the steel strip S is generated, a forced flow in the direction opposite to the advancing direction of the steel strip S will be generated between the steel strip S and the molten metal throttling members 1a, 1b. 16, thereby significantly suppressing the wake 15. Thereby, it is possible to reduce the amount of excess molten metal attached to the steel strip S pulled up from the coating bath.

The molten metal throttling member may include only the steel belt facing portions of the molten metal throttling members 1a and 1b shown in FIG. 6( a ). At this time, the lengths of the steel strip-facing portions of the molten metal throttling members 1a and 1b arranged on both sides of the steel strip in the steel strip advancing direction may be the same.

In the case of the molten metal throttling member as shown in FIG. 6( a ) and above, the cross-sectional shape of the shield 2 may be a rectangle as shown in FIG. 6( b ). At this time, the length of the steel strip facing surface of the shield in the steel strip advancing direction is preferably more than 50% of the length of the steel strip facing surface of the molten metal throttling member in the steel strip advancing direction (when the steel strip of the molten metal throttling member When the length of the opposing surface in the steel strip advancing direction is different on both sides of the steel strip, the steel strip opposing surface of the molten metal throttling part has a smaller length in the steel strip advancing direction. more than 50% of the length in the advancing direction), more preferably equal to the length of the steel strip facing surface of the molten metal throttling part in the steel strip advancing direction (when the steel strip facing surface of the molten metal throttling part is in the length of the steel strip advancing direction When the two sides of the steel strip are different, the length of the steel strip facing surface of the molten metal throttling member in the steel strip advancing direction is equal to the length of the steel strip facing surface of the molten metal throttling member in the steel strip advancing direction).

The size and shape of the molten metal throttling member need to be appropriately determined in consideration of the equipment used, the passing speed of the steel strip, and the like.

The height of the shield 2 in the advancing direction of the steel strip is equal to that of the molten metal throttling member 1, and it is preferable to make the vertical positions of the upper and lower ends of the shield 2 coincide with the molten metal throttling member 1 during installation. When the length of the shield 2 in the advancing direction of the steel plate is shorter than the length of the molten metal throttling member 1 in the advancing direction of the steel plate, the shield 2 is arranged on the side close to the bath surface, that is, preferably the upper end of the shield 2 and the upper end of the molten metal throttling member 1 for roughly the same position. The length of the shield 2 in the width direction of the steel strip is preferably 100 mm or more. Although the upper limit is not limited, if the length increases, the equipment will become too large, so it is preferably about 500 mm or less.

Example

The hot-dip galvanized steel strip manufacturing device shown in Figure 1 was set up on the continuous hot-dip galvanizing production line, and the hot-dip galvanized steel strip manufacturing experiment was carried out. The vertical offset between the back-up rolls in the bath arranged on both sides of the steel strip S is 200 mm, and the distance between the bath surface and the upper end of the back-up rolls in the bath near the bath surface is 80 mm. The diameter of the backup roll in the bath is Φ400mm.

Molten metal throttling part 1, the length in steel strip width direction is set as 2000mm that is equivalent to gas wiping nozzle, and the distance between the upper end of molten metal throttling part and bath surface is 5mm, and the distance with steel strip is 3mm (except comparison Example 5 and Example 4) are fixedly disposed on both sides of the steel strip facing the surface of the steel strip. The shield 2 has a length of 200mm in the width direction of the steel strip, and is directly connected to the position where the frame (frame) extends from the position control device using the servo motor installed on the side of the machine, so that it can be adjusted according to the width of the steel strip. move.

The manufacturing conditions of the hot-dip galvanized steel strip are as follows: the slit of the gas wiping nozzle: 0.8mm, the distance between the gas wiping nozzle and the steel strip: 7mm, the height of the nozzle from the molten zinc bath: 400mm, and the temperature of the molten zinc bath: 460°C. The size is 0.8mm thick x 1.2m wide; the coating weight is 45g/m ² on one side. The distance between the shield 2 and the end of the steel strip is controlled at about 3 mm.

Table 1 shows other manufacturing conditions and the survey results of spatter generation, which is an index of product quality. The specific dimensions and shapes of the molten metal throttling members and shields used in each comparative example and each example are described below. The amount of spatter generation refers to the ratio of the length of the steel strip with spatter defects to the length of the passing steel strip judged by the inspection process under various manufacturing conditions, including slight spatter defects that do not pose a problem in actual use.

Table 1

Comparative example 1 (conventional example) is a case without a molten metal throttling member and a shield. The spatter generation rate was 1.40%.

Comparative example 2 only uses the molten metal throttling part that has the length of steel strip advancing direction and the length of horizontal direction to be 50mm square section respectively, and embodiment 1 is relative to comparative example 2, also additionally sets the length of steel strip advancing direction to be 50 mm, the length of the horizontal direction is 4 mm rectangular cross-section shielding plate (the distance between the molten metal throttling member and the shielding plate is 1 mm). In Comparative Example 2, compared with Comparative Example 1, the spatter generation rate was reduced by about 25%. In Example 1, compared to Comparative Example 1, the spatter generation rate was reduced by almost half, and compared to Comparative Example 2, the spatter generation rate was reduced by about 31%.

In comparative example 3, as shown in FIG. 4( a ), only a molten metal throttling member with a length of 50 mm in both the advancing direction and the horizontal direction of the steel strip and a triangular cross-sectional shape was disposed. In Example 2, compared with Comparative Example 3, as shown in FIG. 4( b ), a shield with the same size and shape as in Example 1 was additionally provided with a rectangular cross-section (the distance between the molten metal throttling member and the shield plate was 1mm). In Comparative Example 3, compared to Comparative Example 1, the spatter generation rate was reduced by about 70%. In Example 2, compared with Comparative Example 1, the spatter generation rate was reduced by 80%, and compared with Comparative Example 3, the spatter generation rate was reduced by about 32%.

Comparative Example 4, as shown in Figure 5(a), only configures steel strips with lengths of 50 mm in both the advancing direction and the horizontal direction and an arc-shaped cross-section (the radius of curvature of the upper surface is 60 mmR, and the radius of curvature of the lower surface is 100 mmR). Molten metal throttling parts. The distance between the lower end of the molten metal throttling part and the steel belt is 3 mm.

Embodiment 3 is relative to comparative example 4, as shown in Figure 5 (b), additionally provided with the shield made as follows: have the cross-sectional shape shown in Figure 5 (b), that is, the length of the steel plate advancing direction is 50mm, by There is a concave arc surface with a radius of curvature slightly larger than the radius of curvature of the arc of the surface of the molten metal throttling part facing the shield, and the surface of the shield facing the molten metal throttling part is in contact with the molten metal joint The distance between the flow parts is 1 mm.

In Comparative Example 4, compared with Comparative Example 1, the spatter generation rate was reduced by about 84%. In Example 3, compared with Comparative Example 1, the spatter generation rate was reduced by about 90%, and compared with Comparative Example 4, the spatter generation rate was reduced by about 30%.

In Comparative Example 5, as shown in FIG. 6(a), only the molten metal throttling members 1a, 1b are arranged, and it is provided with a cover so that the distance between the back-up roll 5 in the bath and the molten metal throttling members 1a, 1b is 30mm. The arc-shaped roll covering part of the bath surface side of the outer peripheral surface of the back-up roll 5 in the bath, and the distance between the steel strip and the molten metal throttling parts 1a, 1b is fixed at 20 mm, and the distance between the upper end and the bath surface The plate-shaped steel belt facing part formed so as to reach 30mm.

In Example 4, compared with Comparative Example 5, as shown in FIG. 6( b ), a shield with a length of 100 mm in the advancing direction of the steel strip and a length of 36 mm in the horizontal direction was additionally installed. The distance between the shield and the molten metal throttling part is 2mm. The ratio of the length of the shield in the direction of advancing the steel strip to the length of the portion of the molten metal throttling member 1b facing the steel strip in the direction of advancing the steel strip is about 90%.

In Comparative Example 5, compared with Comparative Example 1, the spatter generation rate was reduced by about 85%. In Example 4, compared with Comparative Example 1, the spatter generation rate was reduced by about 94%, and compared with Comparative Example 5, the spatter generation rate was reduced by about 33%.

As mentioned above, according to the present invention, even if the width of the steel strip changes, after reducing the excessive amount of molten metal attached to the steel strip within the entire width of the steel strip by using the molten metal throttling member and the shield arranged under the plating bath surface, It is still possible to adjust the coating thickness through the gas wiping nozzle, so the generation of spatter can be greatly reduced. Furthermore, even if the passing speed of the steel strip is greatly increased, the amount of spatter generated can be significantly reduced, so that a hot-dip metal strip without surface defects can be manufactured while maintaining high productivity.

Industrial Utilization Possibility

The apparatus of the present invention reduces the generation of spatter and can be utilized as an apparatus for manufacturing a hot-dip metal strip with excellent surface appearance. The apparatus of the present invention can suppress the generation of spatter even when the steel strip passes at high speed, so it can be used as an apparatus for manufacturing a hot-dip metal strip with excellent surface appearance while maintaining high productivity. Furthermore, the method for producing a steel strip according to the present invention reduces the generation of spatter, and can be utilized as a method for producing a hot-dip galvanized steel strip with excellent surface appearance.

Claims (3)

1. A hot-dip metal strip manufacturing device, by gas wiping nozzle to the steel strip surface spray gas continuously pulled up from the hot-dip metal bath, to carry out the control of the coating adhesion on the steel strip surface, it is characterized in that , under the liquid level of the molten metal tank and on both sides of the steel strip above the bath support roll, there is a molten metal throttling member arranged opposite to the steel strip with a length greater than the width of the steel strip, and on the extension line of the steel strip surface A shield is arranged between the molten metal throttling members disposed facing the steel strip, wherein the molten metal throttling member has a roll cover formed to cover the bath surface side of the outer peripheral surface of the backup roll in the bath. part, and a steel belt facing part arranged above the roll covering part to face the steel belt. 2. hot-dip metal strip manufacturing device as claimed in claim 1, is characterized in that, the length of the steel strip facing face of shielding object in steel strip advance direction is that the steel strip facing face of molten metal throttling part is within the length of steel strip. More than 50% of the length in the advancing direction, when the length of the steel strip facing surface of the molten metal throttling part in the steel strip advancing direction is different on both sides of the steel strip, the steel strip facing surface of the molten metal throttling part advances in the steel strip The steel strip-facing surface of the molten metal throttling member with a small length in the direction is more than 50% of the length in the direction of the steel strip, and the distance between the molten metal throttling member and the shield is 3mm or less. 3. A method for manufacturing a hot-dip metal strip, characterized in that the hot-dip metal strip is hot-dipped using the manufacturing device for a hot-dip metal steel strip according to claim 1 or 2.

Images