JP7111058B2 - Hot-dip metal plated steel strip manufacturing method and continuous hot-dip metal plating equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a hot-dip metal plated steel strip and continuous hot-dip metal plating equipment, and more particularly to gas wiping for adjusting the amount of molten metal deposited on the surface of the steel strip (hereinafter also referred to as "plating deposition amount"). is.

In the continuous hot-dip metal plating line, as shown in FIG. 8, a steel strip S annealed in a continuous annealing furnace in a reducing atmosphere passes through a snout 10 and continuously enters a molten metal bath 14 in a plating bath 12. introduced into After that, the steel strip S is lifted above the molten metal bath 14 through the sink roll 16 and the support roll 18 in the molten metal bath 14, and adjusted to a predetermined plating thickness by the pair of gas wiping nozzles 20A and 20B. , is cooled and guided to the post-process. The gas wiping nozzles 20A and 20B are arranged above the plating bath 12 so as to face each other with the steel strip S interposed therebetween, and blow gas toward both surfaces of the steel strip S from their injection ports. By this gas wiping, surplus molten metal is scraped off, the amount of plating deposited on the surface of the steel strip is adjusted, and the molten metal deposited on the surface of the steel strip is made uniform in the strip width direction and strip longitudinal direction. The gas wiping nozzles 20A and 20B are generally wider than the width of the steel strip in order to accommodate various widths of the steel strip and to cope with positional deviation in the width direction when the steel strip is pulled up. extending outwards.

In such a gas wiping method, the gas blown out from the pair of gas wiping nozzles collides on the outer sides of both ends of the steel strip in the width direction, disturbing the flow of the gas. The wiping force is reduced in the regions near both ends (edge regions), and edge overcoat is likely to occur, in which the coating weight in the edge regions of the surface of the steel strip is relatively increased.

As a method for suppressing edge overcoating, Patent Document 1 discloses that a pair of edge plates are arranged outside both ends in the width direction of a steel strip at a height where a pair of gas wiping nozzles are installed, and the edge plates describes a method for avoiding collision of gas jetted from a gas wiping nozzle of the US.

In the gas wiping process, a so-called splash phenomenon occurs in which the plated metal scatters from both sides of the plated steel strip as the gas collides with both sides of the plated steel strip. Due to this phenomenon, the method of Patent Document 1 using an edge plate has the following problems. That is, the plated metal scattered from both sides of the plated steel strip adheres to the edge plate and forms deposits. From the viewpoint of its function, the edge plate should be positioned close to both ends of the steel strip in the width direction. As a result, deposits that have grown rapidly on the edge plate peel off from the edge plate and adhere to both edge regions of the plated steel strip, thereby deteriorating the plating quality. Therefore, there has been a demand for a method of suppressing edge overcoating without using an edge plate.

As a method for suppressing edge overcoating without using an edge plate, there is a method described in Patent Document 2. Patent Document 2 discloses a gas wiping device in which a pair of wiping nozzles are arranged so that the lines obtained by projecting the gas ejection slits of each wiping nozzle or the extension of the slits onto a plane parallel to the steel strip intersect each other (Patent Document 2, claim 1 and FIGS. 3 to 7), and a pair of wiping nozzles are arranged so that the lines obtained by projecting the gas ejection slits of each wiping nozzle onto a plane parallel to the steel strip are parallel to each other with a gap. A gas wiping device (see claim 4 and FIG. 8 of Patent Document 2) is described.

JP-A-63-105955 JP-A-8-92715

According to the gas wiping device described in Patent Document 2, the gas jet from one nozzle and the gas jet from the other nozzle do not interfere on the outside of both ends in the width direction of the steel strip. Coat can be suppressed. However, due to the splash phenomenon described above, the following problems occur. That is, since there is no interference of the gas jet, splashing becomes violent in both edge regions of the steel strip, and a large amount of plated metal scatters. In this case, the metal scattered by the gas jet from one nozzle colliding with both edge regions of the steel strip rides on the gas jet and passes through the outside of both ends in the width direction of the steel strip and reaches the other nozzle. , causing nozzle clogging. The inventors of the present invention have recognized the problem that linear defects are generated along the longitudinal direction of the steel strip on the surface of the plated steel strip due to this nozzle clogging. Here, the term “linear defect” refers to a defect that weakens the wiping force at a portion of the steel strip surface opposite to the blocked portion of the nozzle, resulting in a relatively thicker coating at that portion and impairing the appearance. . Unless the clogging is removed, it will continue to appear at the same width position of the steel strip, so it will occur linearly along the longitudinal direction of the steel strip.

Therefore, in view of the above problems, the present invention is to manufacture a hot-dip metal plated steel strip that can suppress both the occurrence of edge overcoat and the occurrence of linear defects caused by nozzle clogging without using an edge plate. It is an object of the present invention to provide a method and continuous hot dip metal plating equipment.

In order to solve the above problems, the present inventors aimed to optimize the installation method of a pair of gas wiping nozzles consisting of a first nozzle and a second nozzle arranged to sandwich the steel strip. First, in order to suppress the edge overcoat, it is necessary to prevent the gas jet from one nozzle from interfering with the gas jet from the other nozzle on the outside of both ends in the width direction of the steel strip. It is important to satisfy Condition 1 below. Next, in order to suppress linear defects, it is sufficient to prevent the plating metal carried by the gas jet from one nozzle from reaching the slit-shaped gas injection port of the other nozzle. For this purpose, it is important to satisfy the following condition 2 outside both ends in the width direction of the steel strip.

The gist and configuration of the present invention completed based on the above design concept are as follows.
[1] Continuously immersing a steel strip in a molten metal bath,
A pair of gas wiping nozzles consisting of a first nozzle and a second nozzle arranged to sandwich the steel strip is applied to the steel strip pulled up from the molten metal bath along the width direction of the steel strip. Gas is sprayed from a slit-shaped gas injection port extending in a wide width to adjust the adhesion amount of molten metal on both sides of the steel strip,
A method for manufacturing a hot-dip metal plated steel strip that continuously manufactures a hot-dip metal plated steel strip,
A method for producing a hot-dip metal plated steel strip, wherein the first nozzle and the second nozzle satisfy the following conditions 1 and 2.
Condition 1: On each of the width direction end faces of the steel strip, the gas jet flow passing portion from the first nozzle and the gas jet passing portion from the second nozzle do not overlap.
Condition 2: Outside both ends in the width direction of the steel strip, the gas jet from the first nozzle passes below the lowermost end of the tip of the second nozzle, and the gas jet from the second nozzle passes through the first nozzle. pass below the bottom of the tip of the

[2] The hot dip metal plating according to [1] above, wherein the condition 1 is satisfied by satisfying the following formula (1), and the condition 2 is satisfied by satisfying the following formulas (2A) and (2B). A method of manufacturing a steel strip.
When the gas jet from the first nozzle is the lower jet and the gas jet from the second nozzle is the upper jet,
X>{tan83.7°/(tan83.7°+ _tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/( _tan83.7 ° _−tanθ2 )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)
When the gas jet from the first nozzle is the upper jet and the gas jet from the second nozzle is the lower jet,
X>{tan83.7°/(tan83.7° _−tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7° _{+ tanθ2} )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7°+ _tanθ1 )}×tan6.3°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan83.7°/(tan83.7°+ _tanθ2 )}×tan6.3°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)
Here, the parameters in the formula are defined as the following values on a plane perpendicular to the width direction of the steel strip at each end in the width direction of the steel strip.
X: Distance between the intersection of the steel strip and the center line of the gas jet from the first nozzle and the intersection of the steel strip and the center line of the gas jet from the second nozzle B ₁ : Distance of the first nozzle Slit gap B ₂ : Slit gap of the second nozzle θ ₁ : Angle between the center line of the gas jet from the first nozzle and the horizontal θ ₂ : Angle between the center line of the gas jet from the second nozzle and the horizontal D ₁ : Distance between the slit center of the first nozzle and the steel strip D ₂ : Distance between the slit center of the second nozzle and the steel strip H ₁ : Height of the slit center of the first nozzle H ₂ : The second Height of the slit center of the two nozzles D _min1 : Distance between the lowest end of the tip of the first nozzle and the steel strip D _min2 : Distance between the lowest end of the tip of the second nozzle and the steel strip H _min1 : Height of the lowest end of the tip of the first nozzle H _min2 : Height of the lowest end of the tip of the second nozzle

[3] The above-mentioned [1], wherein the condition 1 is satisfied by satisfying the following formula (1) 'and the condition 2 is satisfied by satisfying the following formulas (2A)' and (2B)'. A method for producing a hot-dip metal plated steel strip.
When the gas jet from the first nozzle is the lower jet and the gas jet from the second nozzle is the upper jet,
X>{tan80.5°/(tan80.5°+ _tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/( _tan80.5 ° _−tanθ2 )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
When the gas jet from the first nozzle is the upper jet and the gas jet from the second nozzle is the lower jet,
X>{tan80.5°/(tan80.5° _−tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5° _{+ tanθ2} )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5°+ _tanθ1 )}×tan9.5°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)'
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan80.5°/(tan80.5°+ _tanθ2 )}×tan9.5°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)'
Here, the parameters in the formula are defined as the following values on a plane perpendicular to the width direction of the steel strip at each end in the width direction of the steel strip.
X: Distance between the intersection of the steel strip and the center line of the gas jet from the first nozzle and the intersection of the steel strip and the center line of the gas jet from the second nozzle B ₁ : Distance of the first nozzle Slit gap B ₂ : Slit gap of the second nozzle θ ₁ : Angle between the center line of the gas jet from the first nozzle and the horizontal θ ₂ : Angle between the center line of the gas jet from the second nozzle and the horizontal D ₁ : Distance between the slit center of the first nozzle and the steel strip D ₂ : Distance between the slit center of the second nozzle and the steel strip H ₁ : Height of the slit center of the first nozzle H ₂ : The second Height of the slit center of the two nozzles D _min1 : Distance between the lowest end of the tip of the first nozzle and the steel strip D _min2 : Distance between the lowest end of the tip of the second nozzle and the steel strip H _min1 : Height of the lowest end of the tip of the first nozzle H _min2 : Height of the lowest end of the tip of the second nozzle

[4] The first nozzle and the second nozzle are
(A) The direction of gas injection from each of the first nozzle and the second nozzle is downward with respect to a horizontal plane, and the angle difference between the direction of gas injection from each of the first nozzle and the second nozzle with respect to the horizontal plane is 8. ° or less , and
(B) a first projection line and a second projection line obtained by projecting the slit center lines of the first nozzle and the second nozzle onto the surface of the steel strip intersect on the width direction center line of the steel strip; And, the first projection line and the second projection line are vertically opposite directions and equiangular with respect to the horizontal line ,
The method for producing a hot-dip metal plated steel strip according to any one of [1] to [3] above.

[5] The method for producing a hot-dip metal plated steel strip according to [4] above, wherein the angle difference is 4° or less.

[6] The method for producing a hot-dip metal plated steel strip according to [4] above, wherein the angle difference is 0°.

[7] A plating tank containing molten metal and forming a molten metal bath;
a slit-shaped gas injection port disposed across the steel strip continuously pulled up from the molten metal bath and extending wider than the steel strip along the width direction of the steel strip; a pair of gas wiping nozzles consisting of a first nozzle and a second nozzle for blowing gas from a mouth toward the steel strip to adjust the adhesion amount of molten metal on both surfaces of the steel strip;
and wherein the first nozzle and the second nozzle satisfy the following formulas (1), (2A) and (2B).
When the gas jet from the first nozzle is the lower jet and the gas jet from the second nozzle is the upper jet,
X>{tan83.7°/(tan83.7°+ _tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/( _tan83.7 ° _−tanθ2 )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)
When the gas jet from the first nozzle is the upper jet and the gas jet from the second nozzle is the lower jet,
X>{tan83.7°/(tan83.7° _−tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7° _{+ tanθ2} )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7°+ _tanθ1 )}×tan6.3°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan83.7°/(tan83.7°+ _tanθ2 )}×tan6.3°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)
Here, the parameters in the formula are defined as the following values on a plane perpendicular to the width direction of the steel strip at each end in the width direction of the steel strip.
X: Distance between the intersection of the steel strip and the center line of the gas jet from the first nozzle and the intersection of the steel strip and the center line of the gas jet from the second nozzle B ₁ : Distance of the first nozzle Slit gap B ₂ : Slit gap of the second nozzle θ ₁ : Angle between the center line of the gas jet from the first nozzle and the horizontal θ ₂ : Angle between the center line of the gas jet from the second nozzle and the horizontal D ₁ : Distance between the slit center of the first nozzle and the steel strip D ₂ : Distance between the slit center of the second nozzle and the steel strip H ₁ : Height of the slit center of the first nozzle H ₂ : The second Height of the slit center of the two nozzles D _min1 : Distance between the lowest end of the tip of the first nozzle and the steel strip D _min2 : Distance between the lowest end of the tip of the second nozzle and the steel strip H _min1 : Height of the lowest end of the tip of the first nozzle H _min2 : Height of the lowest end of the tip of the second nozzle

[8] A plating bath containing molten metal and forming a molten metal bath;
a slit-shaped gas injection port disposed across the steel strip continuously pulled up from the molten metal bath and extending wider than the steel strip along the width direction of the steel strip; a pair of gas wiping nozzles consisting of a first nozzle and a second nozzle for blowing gas from a mouth toward the steel strip to adjust the adhesion amount of molten metal on both surfaces of the steel strip;
wherein the first nozzle and the second nozzle satisfy the following formulas (1)', (2A)' and (2B)'.
When the gas jet from the first nozzle is the lower jet and the gas jet from the second nozzle is the upper jet,
X>{tan80.5°/(tan80.5°+ _tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/( _tan80.5 ° _−tanθ2 )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
When the gas jet from the first nozzle is the upper jet and the gas jet from the second nozzle is the lower jet,
X>{tan80.5°/(tan80.5° _−tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5° _{+ tanθ2} )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5°+ _tanθ1 )}×tan9.5°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)'
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan80.5°/(tan80.5°+ _tanθ2 )}×tan9.5°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)'
Here, the parameters in the formula are defined as the following values on a plane perpendicular to the width direction of the steel strip at each end in the width direction of the steel strip.
X: Distance between the intersection of the steel strip and the center line of the gas jet from the first nozzle and the intersection of the steel strip and the center line of the gas jet from the second nozzle B ₁ : Distance of the first nozzle Slit gap B ₂ : Slit gap of the second nozzle θ ₁ : Angle between the center line of the gas jet from the first nozzle and the horizontal θ ₂ : Angle between the center line of the gas jet from the second nozzle and the horizontal D ₁ : Distance between the slit center of the first nozzle and the steel strip D ₂ : Distance between the slit center of the second nozzle and the steel strip H ₁ : Height of the slit center of the first nozzle H ₂ : The second Height of the slit center of the two nozzles D _min1 : Distance between the lowest end of the tip of the first nozzle and the steel strip D _min2 : Distance between the lowest end of the tip of the second nozzle and the steel strip H _min1 : Height of the lowest end of the tip of the first nozzle H _min2 : Height of the lowest end of the tip of the second nozzle

[9] The first nozzle and the second nozzle are
(A) The direction of gas injection from each of the first nozzle and the second nozzle is downward with respect to a horizontal plane, and the angle difference between the direction of gas injection from each of the first nozzle and the second nozzle with respect to the horizontal plane is 8. ° or less , and
(B) a first projection line and a second projection line obtained by projecting the slit center lines of the first nozzle and the second nozzle onto the surface of the steel strip intersect on the width direction center line of the steel strip; And, the first projection line and the second projection line are vertically opposite directions and equiangular with respect to the horizontal line ,
The continuous hot dip metal plating facility according to the above [7] or [8].

[10] The continuous hot dip metal plating facility according to [9] above, wherein the angle difference is 4° or less.

[11] The continuous hot-dip metal plating facility according to [9] above, wherein the angle difference is 0°.

According to the hot-dip metal plated steel strip manufacturing method and the continuous hot-dip metal plating equipment of the present invention, it is possible to suppress both the occurrence of edge overcoat and the occurrence of linear defects caused by nozzle clogging.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the structure of the continuous hot dip metal plating equipment 100 by one Embodiment of this invention. In one embodiment of the present invention, it is a schematic cross-sectional view of the gas wiping nozzle 20A in a plane perpendicular to the steel strip width direction at one end in the width direction of the steel strip S, showing the configuration of the first nozzle 20A and various FIG. 4 is a diagram for explaining the definition of parameters; 1 is a schematic cross-sectional view of a first nozzle 20A and a second nozzle 20B on a plane perpendicular to the width direction of the steel strip S at one end in the width direction of the steel strip S, in one embodiment of the present invention; FIG. FIG. 3 is a diagram for explaining conditions 1 and 2 to be satisfied; It is a figure for demonstrating the derivation|leading-out process of Formula (1). FIG. 5 is a diagram for explaining corrections required due to the jet spread angle; It is a figure for demonstrating the derivation|leading-out process of Formula (2A). FIG. 3 is a schematic diagram of the first nozzle 20A and the second nozzle 20B viewed in the thickness direction of the steel strip S, and is a diagram for explaining the twist angle φ1 of the _first nozzle and the twist angle φ2 of the _second nozzle. It is a schematic diagram showing the configuration of a general continuous hot-dip metal plating facility.

With reference to FIG. 1, a method for manufacturing a hot-dip metal plated steel strip and a continuous hot-dip metal plating facility 100 (hereinafter also simply referred to as "plating facility") according to an embodiment of the present invention will be described.

Referring to FIG. 1, a plating facility 100 of this embodiment has a snout 10, a plating tank 12 containing molten metal, a sink roll 16, and support rolls 18. As shown in FIG. The snout 10 is a member having a rectangular cross-section perpendicular to the direction in which the steel strip S passes, and which defines a space through which the steel strip S passes. there is In one embodiment, the steel strip S annealed in a continuous annealing furnace in a reducing atmosphere passes through the snout 10 and is continuously introduced into the molten metal bath 14 within the plating tank 12 . After that, the steel strip S is lifted above the molten metal bath 14 via a sink roll 16 and a support roll 18 in the molten metal bath 14, and is wiped by a pair of gas wiping nozzles consisting of a first nozzle 20A and a second nozzle 20B. After being adjusted to the plating thickness of , it is cooled and led to the post-process.

A first nozzle 20A and a second nozzle 20B, which are a pair of gas wiping nozzles, are arranged above the plating bath 12 so as to face each other with the steel strip S interposed therebetween. Referring to FIG. 2 in addition to FIG. 1, the first nozzle 20A blows gas toward the steel strip S from a slit-shaped gas injection port 28 extending along the width direction of the steel strip at its tip, Adjust the amount of plating on the surface of the steel strip. The same applies to the second nozzle 20B. The pair of nozzles 20A and 20B scrape off surplus molten metal, adjust the coating amount on both sides of the steel strip S, and is equalized with

For example, as shown in FIG. 7, the first nozzle 20A and the second nozzle 20B correspond to various widths of the steel strip, and to deal with misalignment in the width direction when the steel strip is pulled up. It is configured to be longer and extends to the outside from both ends in the width direction of the steel strip. That is, the slit-shaped gas injection ports 28 of the first nozzle 20A and the second nozzle 20B extend wider than the steel strip along the width direction of the steel strip.

Further, as shown in FIG. 2, the first nozzle 20A has a nozzle header 22, and an upper nozzle member 24 and a lower nozzle member 26 connected to the nozzle header 22. As shown in FIG. The tip portions of the upper and lower nozzle members 24 and 26 have a pair of surfaces facing each other in parallel in a cross-sectional view perpendicular to the width direction of the steel strip S, and these pair of surfaces define a slit-shaped gas injection port 28. ing. The gas injection port 28 extends along the width direction of the steel strip S. The distance between the center of the slit of the first nozzle 20A and the steel strip S is constant in the width direction of the steel strip. The shape of the cross section of the first nozzle 20A perpendicular to the width direction of the steel strip is tapered toward the tip. The thickness of the tips of the upper and lower nozzle members 24, 26 is not particularly limited, but may be about 1 to 3 mm. Also, the opening width (nozzle gap B ₁ ) of the gas injection port is not particularly limited, but can be about 0.5 to 3.0 mm. Gas supplied from a gas supply mechanism (not shown) passes through the interior of the header 22, further passes through the gas flow path defined by the upper and lower nozzle members 24 and 26, and is jetted from the gas jet port 28 to form the steel strip S. sprayed onto the surface. The header pressure P, which is defined as the gas pressure in the nozzle header 22, is not particularly limited, and may be set within a general range of 1 to 100 kPa according to the desired plating deposition amount.

The second nozzle 20B also has a similar configuration. The shape of the second nozzle 20B and dimensions such as the nozzle gap are preferably the same as those of the first nozzle 20A.

In the manufacturing method of the hot-dip metal plated steel strip of the present embodiment, the steel strip S is continuously immersed in the molten metal bath 14, and the steel strip S is sandwiched between the steel strips S pulled up from the molten metal bath 14. Gas is sprayed from the first nozzle 20A and the second nozzle 20B to adjust the adhesion amount of the molten metal on both sides of the steel strip S, thereby continuously manufacturing the hot-dip metal plated steel strip.

Conditions to be satisfied in this embodiment will be described with reference to FIG. In this embodiment, it is essential to install the first nozzle 20A and the second nozzle 20B so as to satisfy the following conditions 1 and 2.
Condition 1: The passage portion C1 of the gas jet F1 from the _first nozzle 20A and the passage portion _C2 of the gas jet F2 from the _second nozzle 20B on _each of the width direction end faces of the steel strip S do not overlap.
Condition 2: Outside both ends in the width direction of the steel strip S, the gas jet F1 from the _first nozzle 20A passes below the lowermost end _Pmin2 of the tip of the second nozzle 20B, and the gas jet from the second nozzle 20B F2 passes below the lowermost end _Pmin1 of the tip of the _first nozzle 20A.

FIG. 3 illustrates a state in which conditions 1 and 2 are simultaneously satisfied in a plane perpendicular to the width direction of the steel strip S at one end in the width direction of the steel strip S, but the other end in the width direction of the steel strip S is similar. , Condition 1 and Condition 2 must be satisfied at the same time.

If Condition 1 is satisfied, the gas jet F1 from the _first nozzle 20A and the gas jet F2 from the _second nozzle 20B do not interfere with each other on the outer sides of both ends of the steel strip S in the width direction. Therefore, edge overcoating can be suppressed. Further, if condition 2 is satisfied, the plating metal conveyed by the gas jet F1 from the _first nozzle 20A does not reach the gas injection port 28 of the second nozzle 20B and is conveyed to the gas jet F2 by the _second nozzle 20B. The plated metal to be applied does not reach the gas injection port 28 of the first nozzle 20A. Therefore, linear defects can be suppressed.

That is, by satisfying both conditions 1 and 2, it is possible to suppress both the occurrence of edge overcoat and the occurrence of linear defects caused by nozzle clogging.

In this specification, the term "gas jet" means the flow of gas injected from each nozzle, and can be specified by measuring with an air velocity measuring means such as a hot wire anemometer. As a first embodiment, a "gas jet" is defined as a region having a wind speed of 22% or more with respect to the wind speed at the center of the jet (a region having a kinetic energy of 5% or more with respect to the kinetic energy at the center of the jet). . That is, the outermost part of the gas jet is the boundary where the wind speed is 22% of the jet center (the kinetic energy is 5% of the jet center).

The gas jet widens as it advances in the direction of gas injection (that is, the direction of the gas jet center). As a result of the inventors' examination by measuring the gas jet wind velocity, it was found that various nozzle dimensions such as the slit gap, header pressure, etc., as long as the nozzle with the above-described general configuration is used and the general gas injection conditions are adopted. It was found that the gas jet diverges by 6.3° almost independently of the gas injection conditions. The effect of the present invention can be obtained when the gas jet according to the above definition satisfies both the condition 1 and the condition 2.

As a second embodiment, the "gas jet" is defined as a region having a wind speed of 10% or more with respect to the wind speed at the center of the jet (a region having a kinetic energy of 1% or more with respect to the kinetic energy at the center of the jet). be done. In this case, the outermost part of the gas jet is the boundary where the wind speed is 10% of the jet center (the kinetic energy is 1% of the jet center). In this case, the gas jet was found to diverge by 9.5° as it progressed in the direction of gas injection. If the gas jet according to this definition satisfies both Condition 1 and Condition 2, the effects of the present invention can be obtained more fully.

Satisfaction of condition 1 can be confirmed by the following method. That is, from the center of the upper jet (gas jet F ₁ in FIG. 3) to the center of the lower jet (gas jet F ₂ in FIG. 3), for example, at a position 10 mm outside from one end in the width direction of the steel strip S, the hot wire anemometer Measure the wind speed with, etc., and obtain the wind speed distribution. In the wind speed distribution, when there is a region between the center of the upper jet and the center of the lower jet where the wind speed is 22% or less of the center wind speed of the upper jet and 22% or less of the center wind speed of the lower jet can be determined to satisfy condition 1. The same applies to the other end of the steel strip S in the width direction. In addition, in the case of the second embodiment, "22%" is read as "10%".

Satisfaction of Condition 2 can be confirmed by the following method. That is, since the wind speed at the lowest end P _min2 of the tip of the second nozzle cannot be _measured , the steel strip The wind speed is measured with a hot-wire anemometer or the like at two positions 10 mm apart from each end of S in the width direction. If the measured wind speed is 22% or less of the central wind speed of the gas jet F1 from the _first nozzle 20A, it can be determined that the gas jet F1 from the _first nozzle 20A passes below the lowermost end _Pmin2 . At that time, it is preferable to stop the injection of gas from the second nozzle 20B. Similarly, in the vicinity of the lowermost end P _min1 of the tip of the first nozzle (for example, a position shifted by 1 mm toward the steel strip S), and in the width direction, a position 10 mm outside each of the width direction ends of the steel strip S Measure the wind speed with a hot wire anemometer or the like at two locations. If the measured wind speed is 22% or less of the central wind speed of the gas jet F2 from the _second nozzle 20B, it can be determined that the gas jet F2 from the _second nozzle 20B passes below the lowermost end _Pmin1 . At that time, it is preferable to stop the injection of the gas from the first nozzle 20A.

Here, with reference to FIGS. 2 and 3, various parameters on a plane perpendicular to the width direction of the steel strip at each of the ends in the width direction of the steel strip are defined as follows. 2 and 3 show the plane perpendicular to the width direction of the steel strip at one end in the width direction of the steel strip S, the same parameters are applied to the plane perpendicular to the width direction of the steel strip at the other end. shall be defined.
X ₁ : intersection of the center line of the gas jet F ₁ from the first nozzle 20A and the steel strip S X ₂ : intersection of the center line of the gas jet F ₂ from the second nozzle 20B and the steel strip S X: intersection X ₁ and Distance from intersection X2 ₍ offset amount)
As shown in FIG. 2, the "center line of the gas jet" is defined as a straight line that is parallel to a pair of parallel planes defining the gas injection port 28 and that passes through the center of the slit.

[Parameters for the first nozzle 20A (see FIG. 2)]
B ₁ : Slit gap of the first nozzle 20A θ ₁ : Angle formed by the center line of the gas jet flow F ₁ from the first nozzle 20A and the horizontal line (gas injection angle)
D ₁ : _Distance between the center of the slit of the first nozzle _20A and the steel strip S H ₁ : Height of the center of the slit of the first nozzle 20A distance H _min1 : Height of the lowest end P _min1 of the tip of the first nozzle 20A

[Parameters for Second Nozzle 20B]
For the second nozzle 20B, similar parameters are defined by changing the suffix to "2" as follows.
B ₂ : Slit gap of the second nozzle 20B θ ₂ : Angle formed by the center line of the gas jet flow F ₂ from the second nozzle 20B and the horizontal line (gas injection angle)
D ₂ : _Distance between the center of the slit of the second nozzle _20B and the steel strip S H ₂ : Height of the center of the slit of the second nozzle 20B distance H _min2 : the height of the lowest end P _min2 of the tip of the second nozzle 20B

The "height" at the center of the slit and the lowest end means the height from a predetermined reference plane (for example, the bath surface at a predetermined time).

Here, as described above, in the case of the first embodiment, the gas jet diverges by 6.3° as it advances in the direction of gas injection. Therefore, the inventors of the present invention have succeeded in generalizing the relationships of the above various parameters for satisfying the conditions 1 and 2 in consideration of this spread.

First, condition 1 is satisfied by satisfying the following equation (1).
When the gas jet F1 from the _first nozzle is the lower jet and the gas jet F2 from the _second nozzle is the upper jet,
X>{tan83.7°/(tan83.7°+ _tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/( _tan83.7 ° _−tanθ2 )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)
When the gas jet F1 from the _first nozzle is the upper jet and the gas jet F2 from the _second nozzle is the lower jet,
X>{tan83.7°/(tan83.7° _−tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7° _{+ tanθ2} )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)

With reference to FIG. 4 in addition to FIGS. 2 and 3, the process of deriving equation (1) will be described. FIG. 4 relates to the case where the gas jet F1 from the _first nozzle is the lower jet and the gas jet F2 from the _second nozzle is the upper jet. here,
Length of line segment LO=tan6.3°×D ₁ /cos θ ₁ +0.5×B ₁
becomes. And, assuming that the angle LON is right,
Length of line segment LN = Length of line segment LO/cos θ ₁
becomes. i.e.
Length of line segment LN = length of line segment MN + length of line segment LM
=tan6.3°×D1/ _cos2θ1 +0.5 _{× B1 /} ^cosθ1
becomes. However, due to the jet divergence angle of 6.3°, the angle LON is not actually a right angle. Therefore, in the above formula, the length of the line segment MN is not accurate and needs to be corrected. Now referring to FIG. 5,
Length of line segment MN = {tan83.7°/(tan83.7° + tan θ ₁ )} × length of line segment MN' Length of line segment PQ = {tan83.7°/(tan83.7° - tan θ) ₁ )}×the length of the line segment PQ′. That is, the upper side of the gas jet must be multiplied by the correction factor {tan83.7°/(tan83.7°+ _tanθ1 )}, and the lower side of the gas jet must be multiplied by the correction coefficient {tan83.7°/(tan83 .7°-tan θ ₁ )}.

Therefore, if the length of the line segment LN in FIG. 4 is expressed accurately,
Length of line segment LN = length of line segment MN + length of line segment LM
= {tan 83.7°/(tan 83.7° + tan θ ₁ )} x tan 6.3° x D ₁ /cos ² θ ₁
+0.5×B ₁ /cos θ ₁
becomes. Regarding the gas jet flow F2 from the _second nozzle, if the length of the line segment RS in FIG.
Length of line segment RS={tan83.7°/(tan83.7°−tan θ ₂ )}×tan 6.3°×D ₂ /cos ² θ ₂
+0.5×B ₂ /cos θ ₂
becomes. In order to satisfy condition 1,
Since it suffices to satisfy X>the length of the line segment LN+the length of the line segment RS, the above equation (1) is derived. When the gas jet F1 from the _first nozzle is the upper jet and the gas jet F2 from the _second nozzle is the lower jet, the above equation (1) is derived in the same manner.

The left side of equation (1) is the offset amount X. As shown in FIG. 4, when the gas jet F1 from the _first nozzle is the lower jet and the gas jet F2 from the _second nozzle is the upper jet teeth,
X=height of intersection point X ₂ −height of intersection point X ₁ =(H ₂ −D ₂ tan θ ₂ )−(H ₁ −D ₁ tan θ ₁ )
becomes. When the gas jet F1 from the _first nozzle is the upper jet and the gas jet F2 from the _second nozzle is the lower jet,
X=height of intersection point X ₁ −height of intersection point X ₂ =(H ₁ −D ₁ tan θ ₁ )−(H ₂ −D ₂ tan θ ₂ )
becomes.

Next, Condition 2 is satisfied by satisfying Equations (2A) and (2B) below.
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7°+ _tanθ1 )}×tan6.3°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan83.7°/(tan83.7°+ _tanθ2 )}×tan6.3°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)

With reference to FIG. 6 in addition to FIGS. 2 and 3, the process of deriving equation (2A) will be described. In FIG. 6,
Length of line segment TU=0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7°+ _tanθ1 )}×tan6.3°
×(D ₁ +D _min2 )/cos ² θ ₁
Length of line segment VW = (D ₁ + D _min2 ) tan θ ₁
becomes. Here, the height of the point W is obtained by subtracting the length of the line segment VW from the height H1 of the _point V.
Height of point W = H ₁ - (D ₁ + D _min2 ) tan θ ₁
The height of the point T is obtained by adding the length of the line segment TU to the height of the point W. In order to satisfy the condition 2, the height _Hmin2 of the lowermost end _Pmin2 should be higher than the height of the point T. in short,
Since it suffices to satisfy H _min2 >H ₁ −(D ₁ +D _min2 )tan θ ₁ +length of line segment TU, the above equation (2A) is derived. Equation (2B) is also derived from a similar way of thinking.

In the case of the second embodiment, as already mentioned, the gas jet diverges by 9.5° as it progresses in the direction of gas injection. Therefore, the general formula for satisfying condition 1 and condition 2 is as follows.
When the gas jet F1 from the _first nozzle is the lower jet and the gas jet F2 from the _second nozzle is the upper jet,
X>{tan80.5°/(tan80.5°+ _tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/( _tan80.5 ° _−tanθ2 )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
When the gas jet F1 from the _first nozzle is the upper jet and the gas jet F2 from the _second nozzle is the lower jet,
X>{tan80.5°/(tan80.5° _−tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5° _{+ tanθ2} )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5°+ _tanθ1 )}×tan9.5°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)'
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan80.5°/(tan80.5°+ _tanθ2 )}×tan9.5°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)'

Next, as a means for making equation (1) compatible with equations (2A) and (2B),
(A) As shown in FIG. 2, the first nozzle and the second nozzle are directed downward with respect to the horizontal plane, and the gas injection angle is set.
(B) As shown in FIG. 7, starting from the center of the slit on the center point in the width direction of the steel strip, twist the first nozzle and the second nozzle upside down with respect to the horizontal plane to form a twist angle.
(C) The heights of the first nozzle and the second nozzle are made different.
Among them, (A) is essential, and at least one of (B) and (C) is combined.

For example, as a first aspect,
(A) The direction of gas injection from each of the first nozzle 20A and the second nozzle 20B is downward with respect to the horizontal plane, and the angle difference between the direction of gas injection from each of the first nozzle and the second nozzle with respect to the horizontal plane is 8. ° or less (that is, the difference between the gas injection angle θ1 of the _first nozzle and the gas injection angle θ2 of the _second nozzle is 8° or less), and
(B) A _first projection line L1 and a _second projection line L2 formed by projecting the center lines of the slits of the first nozzle 20A and the second nozzle 20B onto the surface of the steel strip S are the center lines of the steel strip S in the width direction. Intersect on L3, and the _first projection line L1 and the _second projection line L2 _are vertically opposite and equiangular with respect to the horizontal line (see FIG. 7),
Installation of the first nozzle 20A and the second nozzle 20B can be mentioned. In FIG. 7, the twist angle φ ₁ of the first nozzle is the angle between the first projection line and the horizontal line, the twist angle φ ₂ of the second nozzle is the angle between the second projection line and the horizontal line, φ ₁ =φ ₂ .

In the case of this aspect, as is clear from the examples described later, the conditions (gas injection angle θ ₁ , gas injection θ ₂ , twist angle φ ₁ , and twist angle φ ₂ ).

Here, the difference between the gas injection angle θ1 of the _first nozzle and the gas injection angle θ2 of the _second nozzle is preferably 4° or less, more preferably 0°. In this case, as is clear from the examples described later, the condition (gas injection There is a combination of angle θ ₁ , gas injection angle θ ₂ , twist angle φ ₁ , and twist angle φ ₂ ).

In the case of this first aspect, the distances D ₁ and D ₂ between the centers of the slits of the first nozzle 20A and the second nozzle 20B and the steel strip S are 0.67<D ₁ /D ₂ <1. 5, and more preferably D ₁ =D ₂ .

In the case of the first aspect, although the nozzles with the gas jet flow upward are switched between one end and the other end in the width direction of the steel strip, both conditions 1 and 2 can be satisfied at both ends.

Also, as a second aspect,
(A) The direction of gas injection from each of the first nozzle 20A and the second nozzle 20B is downward with respect to the horizontal plane, and the angle difference between the direction of gas injection from each of the first nozzle and the second nozzle with respect to the horizontal plane is 8. ° or less (that is, the difference between the gas injection angle θ1 of the _first nozzle and the gas injection angle θ2 of the _second nozzle is 8° or less), and
(C) A _first projection line L1 and a _second projection line L2 formed by projecting the center lines of the slits of the first nozzle 20A and the second nozzle 20B onto the surface of the steel strip S are spaced apart and parallel to each other. so that
Installation of the first nozzle 20A and the second nozzle 20B can be mentioned. This predetermined "interval" is the height difference between the first nozzle 20A and the second nozzle 20B.

In the second mode, the nozzle height difference generated at both ends in the width direction of the steel strip due to the twisting of the nozzle in the first mode is simply reduced to the first nozzle 20A and the second nozzle 20B without twisting the nozzles. Attach by varying the height. In other words, in the case of the second aspect, conditions 1 and 2 can be satisfied at both ends without switching the nozzles with the gas jet flow upward between one end and the other end in the width direction of the steel strip.

Also in the case of the _second aspect, the difference between the gas injection angle θ1 of the _first nozzle and the gas injection angle θ2 of the second nozzle is preferably 4° or less, more preferably 0°. . Moreover, it is preferable to satisfy 0.67<D ₁ /D ₂ <1.5, and more preferably D ₁ =D ₂ .

The gas jetted from the gas wiping nozzle is not particularly limited, and can be air, for example, but may be an inert gas. By using an inert gas, oxidation of the molten metal on the surface of the steel strip can be prevented, so that uneven viscosity of the molten metal can be suppressed. Inert gases include, but are not limited to, nitrogen, argon, helium, carbon dioxide, and the like.

Further, in the present embodiment, the molten metal preferably contains 0.1 to 10% by mass of Al, with the balance being Zn and unavoidable impurities. In addition, optionally Mg: 0.2 to 10% by mass may be included.

Hot-dip galvanized steel strips manufactured by the manufacturing method and the plating equipment of the present invention include hot-dip galvanized steel strips, which are galvanized steel strips (GI) that are not subjected to alloying treatment after hot-dip galvanizing treatment. , and galvanized steel sheets (GA) subjected to alloying treatment.

A hot-dip galvanized steel strip production test was conducted on a hot-dip galvanized steel strip production line. The plating equipment shown in FIG. 1 was used in each invention example and comparative example. In the present embodiment, the first aspect, in which means (A) and (B) are combined, aims to satisfy both conditions 1 and 2.

Various parameters regarding the first nozzle and the second nozzle were set as follows.
Thickness of tips of upper and lower nozzle members: 2.0 mm
Slit gap: _B1 =B2 ₌ 1.0mm
D1 = D2 _{= 10} mm
Gas injection angles θ ₁ and θ ₂ : listed in Table 1 Nozzle torsion angles φ ₁ and φ ₂ : listed in Table 1 Slit center heights H ₁ and H ₂ : 200 mm

As a method of supplying gas to the gas wiping nozzle, a method of supplying gas pressurized to a header pressure of 30 kPa by a compressor was adopted. Air was used as the gas type. Thus, a steel strip having a thickness of 0.8 mm and a width of 1000 mm was threaded at a strip speed of 100 mpm to produce a hot-dip galvanized steel strip.

Each level No. 1 to 42, the gas jet with a jet divergence angle of 6.3° satisfies condition 1 based on formula (1), and the gas jet with a jet divergence angle of 9.5° satisfies condition 1. , was determined based on formula (1)', which is a stricter conditional formula.
[Equation (1) determination]
x: Expression (1) is not satisfied at both end faces in the width direction of the steel strip.
○: Expression (1) is satisfied at both end faces in the width direction of the steel strip.
[Formula (1) 'determination]
x: Expression (1)′ is not satisfied at both end faces in the width direction of the steel strip.
◯: Expression (1)′ is satisfied at both end faces in the width direction of the steel strip.

Each level No. 1 to 42, the gas jet with a jet divergence angle of 6.3° satisfies condition 2 based on equations (2A) and (2B), and the gas jet with a jet divergence angle of 9.5° Satisfaction of 2 was determined on the basis of formulas (2A)' and (2B)', which are stricter conditional formulas.
[Equation (2) determination]
Table X: one end in the width direction of the steel strip does not satisfy the formula (2A).
Table ○: both ends in the width direction of the steel strip satisfy the formula (2A).
Back ×: One end in the width direction of the steel strip does not satisfy the formula (2B).
Back ○: Both ends in the width direction of the steel strip satisfy the formula (2B).
[Formula (2) 'determination]
Table X: one end in the width direction of the steel strip does not satisfy the formula (2A)'.
Table ○: Both ends in the width direction of the steel strip satisfy the formula (2A)'.
Back x: one end in the width direction of the steel strip does not satisfy the formula (2B)'.
Back ○: Both ends in the width direction of the steel strip satisfy the formula (2B)′.

[Evaluation of Edge Overcoat Ratio]
One side of the produced hot-dip galvanized steel strip was evaluated for edge overcoat rate (EOC rate) according to the following definition. Table 1 shows the results. An EOC rate of 10% or less was judged to be good, and an EOC rate of 4% or less was judged to be particularly good.
EOC rate = (adhesion amount on one side edge region of steel strip + adhesion amount on opposite side edge region) / (2 x adhesion amount at center of steel strip width direction) x 100 [%]

[Evaluation of linear defect rate]
One side of the manufactured hot-dip galvanized steel strip was evaluated for linear defect rate according to the following definition. Table 1 shows the results. A linear defect rate of 1% or less was judged to be good, and a case of 0.05% or less was judged to be particularly good.
Linear defect rate = length of steel strip with defects / length of manufactured steel strip

As is clear from Table 1, with regard to condition 1, by satisfying formula (1), the EOC rate can be reduced to 10% or less, and by satisfying formula (1)', which is a more stringent conditional formula, The EOC rate was able to be 4% or less. Regarding condition 2, by satisfying the expressions (2A) and (2B), the linear defect rate can be reduced to 1% or less. , the linear defect rate could be reduced to 0.05% or less. Thus, it can be seen that both the edge overcoat and the linear defect can be suppressed by satisfying both the conditions 1 and 2.

According to the hot-dip metal plated steel strip manufacturing method and the continuous hot-dip metal plating equipment of the present invention, it is possible to suppress both the occurrence of edge overcoat and the occurrence of linear defects caused by nozzle clogging.

100 continuous molten metal plating equipment 10 snout 12 plating tank 14 molten metal bath 16 sink roll 18 support roll 20A gas wiping nozzle (first nozzle)
20B Gas wiping nozzle (second nozzle)
22 Nozzle header 24 Upper nozzle member 26 Lower nozzle member 28 Gas injection port S Steel strip F ₁ Gas jet from first nozzle F ₂ Gas jet from second nozzle C ₁ Passing portion of gas jet from first nozzle C ₂ Second nozzle P min 1 Bottom end of the tip of the first nozzle P _min 2 _Bottom end of the tip of the second nozzle X ₁ Intersection point of the center line of the gas jet from the first nozzle and the steel strip X ₂ Second nozzle Intersection point X between the center line of the gas jet and the steel strip Distance between intersection _point X1 and intersection point X2 ₍ offset amount)

Claims (11)

continuously immersing a steel strip in a molten metal bath,
A pair of gas wiping nozzles consisting of a first nozzle and a second nozzle arranged to sandwich the steel strip is applied to the steel strip pulled up from the molten metal bath along the width direction of the steel strip. Gas is sprayed from a slit-shaped gas injection port extending in a wide width to adjust the adhesion amount of molten metal on both sides of the steel strip,
A method for manufacturing a hot-dip metal plated steel strip that continuously manufactures a hot-dip metal plated steel strip,
A method for producing a hot-dip metal plated steel strip, wherein the first nozzle and the second nozzle satisfy the following conditions 1 and 2.
Condition 1: On each of the width direction end faces of the steel strip, the gas jet flow passing portion from the first nozzle and the gas jet passing portion from the second nozzle do not overlap.
Condition 2: Outside both ends in the width direction of the steel strip, the gas jet from the first nozzle passes below the lowermost end of the tip of the second nozzle, and the gas jet from the second nozzle passes through the first nozzle. pass below the bottom of the tip of the The production of the hot-dip metal plated steel strip according to claim 1, wherein the condition 1 is satisfied by satisfying the following formula (1), and the condition 2 is satisfied by satisfying the following formulas (2A) and (2B). Method.
When the gas jet from the first nozzle is the lower jet and the gas jet from the second nozzle is the upper jet,
X>{tan83.7°/(tan83.7°+ _tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/( _tan83.7 ° _−tanθ2 )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)
When the gas jet from the first nozzle is the upper jet and the gas jet from the second nozzle is the lower jet,
X>{tan83.7°/(tan83.7° _−tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7° _{+ tanθ2} )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7°+ _tanθ1 )}×tan6.3°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan83.7°/(tan83.7°+ _tanθ2 )}×tan6.3°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)
Here, the parameters in the formula are defined as the following values on a plane perpendicular to the width direction of the steel strip at each end in the width direction of the steel strip.
X: Distance between the intersection of the steel strip and the center line of the gas jet from the first nozzle and the intersection of the steel strip and the center line of the gas jet from the second nozzle B ₁ : Distance of the first nozzle Slit gap B ₂ : Slit gap of the second nozzle θ ₁ : Angle between the center line of the gas jet from the first nozzle and the horizontal θ ₂ : Angle between the center line of the gas jet from the second nozzle and the horizontal D ₁ : Distance between the slit center of the first nozzle and the steel strip D ₂ : Distance between the slit center of the second nozzle and the steel strip H ₁ : Height of the slit center of the first nozzle H ₂ : The second Height of the slit center of the two nozzles D _min1 : Distance between the lowest end of the tip of the first nozzle and the steel strip D _min2 : Distance between the lowest end of the tip of the second nozzle and the steel strip H _min1 : Height of the lowest end of the tip of the first nozzle H _min2 : Height of the lowest end of the tip of the second nozzle The hot dip metal plated steel according to claim 1, wherein the condition 1 is satisfied by satisfying the following formula (1)', and the condition 2 is satisfied by satisfying the following formulas (2A)' and (2B)'. Obi production method.
When the gas jet from the first nozzle is the lower jet and the gas jet from the second nozzle is the upper jet,
X>{tan80.5°/(tan80.5°+ _tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/( _tan80.5 ° _−tanθ2 )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
When the gas jet from the first nozzle is the upper jet and the gas jet from the second nozzle is the lower jet,
X>{tan80.5°/(tan80.5° _−tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5° _{+ tanθ2} )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5°+ _tanθ1 )}×tan9.5°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)'
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan80.5°/(tan80.5°+ _tanθ2 )}×tan9.5°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)'
Here, the parameters in the formula are defined as the following values on a plane perpendicular to the width direction of the steel strip at each end in the width direction of the steel strip.
X: Distance between the intersection of the steel strip and the center line of the gas jet from the first nozzle and the intersection of the steel strip and the center line of the gas jet from the second nozzle B ₁ : Distance of the first nozzle Slit gap B ₂ : Slit gap of the second nozzle θ ₁ : Angle between the center line of the gas jet from the first nozzle and the horizontal θ ₂ : Angle between the center line of the gas jet from the second nozzle and the horizontal D ₁ : Distance between the slit center of the first nozzle and the steel strip D ₂ : Distance between the slit center of the second nozzle and the steel strip H ₁ : Height of the slit center of the first nozzle H ₂ : The second Height of the slit center of the two nozzles D _min1 : Distance between the lowest end of the tip of the first nozzle and the steel strip D _min2 : Distance between the lowest end of the tip of the second nozzle and the steel strip H _min1 : Height of the lowest end of the tip of the first nozzle H _min2 : Height of the lowest end of the tip of the second nozzle The first nozzle and the second nozzle are
(A) The direction of gas injection from each of the first nozzle and the second nozzle is downward with respect to a horizontal plane, and the angle difference between the direction of gas injection from each of the first nozzle and the second nozzle with respect to the horizontal plane is 8. ° or less , and
(B) a first projection line and a second projection line obtained by projecting the slit center lines of the first nozzle and the second nozzle onto the surface of the steel strip intersect on the width direction center line of the steel strip; And, the first projection line and the second projection line are vertically opposite directions and equiangular with respect to the horizontal line ,
A method for producing a hot-dip metal plated steel strip according to any one of claims 1 to 3. The method for producing a hot-dip metal plated steel strip according to claim 4, wherein the angle difference is 4° or less. The method for producing a hot-dip metal plated steel strip according to claim 4, wherein the angle difference is 0°. a plating bath containing molten metal and forming a molten metal bath;
a slit-shaped gas injection port disposed across the steel strip continuously pulled up from the molten metal bath and extending wider than the steel strip along the width direction of the steel strip; a pair of gas wiping nozzles consisting of a first nozzle and a second nozzle for blowing gas from a mouth toward the steel strip to adjust the adhesion amount of molten metal on both surfaces of the steel strip;
and wherein the first nozzle and the second nozzle satisfy the following formulas (1), (2A) and (2B).
When the gas jet from the first nozzle is the lower jet and the gas jet from the second nozzle is the upper jet,
X>{tan83.7°/(tan83.7°+ _tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/( _tan83.7 ° _−tanθ2 )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)
When the gas jet from the first nozzle is the upper jet and the gas jet from the second nozzle is the lower jet,
X>{tan83.7°/(tan83.7° _−tanθ1 )}× _tan6.3 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7° _{+ tanθ2} )}× _tan6.3 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan83.7°/(tan83.7°+ _tanθ1 )}×tan6.3°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan83.7°/(tan83.7°+ _tanθ2 )}×tan6.3°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)
Here, the parameters in the formula are defined as the following values on a plane perpendicular to the width direction of the steel strip at each end in the width direction of the steel strip.
X: Distance between the intersection of the steel strip and the center line of the gas jet from the first nozzle and the intersection of the steel strip and the center line of the gas jet from the second nozzle B ₁ : Distance of the first nozzle Slit gap B ₂ : Slit gap of the second nozzle θ ₁ : Angle between the center line of the gas jet from the first nozzle and the horizontal θ ₂ : Angle between the center line of the gas jet from the second nozzle and the horizontal D ₁ : Distance between the slit center of the first nozzle and the steel strip D ₂ : Distance between the slit center of the second nozzle and the steel strip H ₁ : Height of the slit center of the first nozzle H ₂ : The second Height of the slit center of the two nozzles D _min1 : Distance between the lowest end of the tip of the first nozzle and the steel strip D _min2 : Distance between the lowest end of the tip of the second nozzle and the steel strip H _min1 : Height of the lowest end of the tip of the first nozzle H _min2 : Height of the lowest end of the tip of the second nozzle a plating bath containing molten metal and forming a molten metal bath;
a slit-shaped gas injection port disposed across the steel strip continuously pulled up from the molten metal bath and extending wider than the steel strip along the width direction of the steel strip; a pair of gas wiping nozzles consisting of a first nozzle and a second nozzle for blowing gas from a mouth toward the steel strip to adjust the adhesion amount of molten metal on both surfaces of the steel strip;
wherein the first nozzle and the second nozzle satisfy the following formulas (1)', (2A)' and (2B)'.
When the gas jet from the first nozzle is the lower jet and the gas jet from the second nozzle is the upper jet,
X>{tan80.5°/(tan80.5°+ _tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/( _tan80.5 ° _−tanθ2 )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
When the gas jet from the first nozzle is the upper jet and the gas jet from the second nozzle is the lower jet,
X>{tan80.5°/(tan80.5° _−tanθ1 )}× _tan9.5 °×D1 _/ ^cos2θ1
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5° _{+ tanθ2} )}× _tan9.5 °×D2/ ^cos2θ2
+0.5×B ₂ /cos θ ₂ (1)'
H _min2 >H ₁ −(D ₁ +D _min2 ) tan θ ₁
+0.5×B ₁ /cos θ ₁
+{tan80.5°/(tan80.5°+ _tanθ1 )}×tan9.5°
×(D ₁ +D _min2 )/cos ² θ ₁ (2A)'
H _min1 >H ₂ −(D ₂ +D _min1 ) tan θ ₂
+0.5×B ₂ /cos θ ₂
+{tan80.5°/(tan80.5°+ _tanθ2 )}×tan9.5°
×(D ₂ +D _min1 )/cos ² θ ₂ (2B)'
Here, the parameters in the formula are defined as the following values on a plane perpendicular to the width direction of the steel strip at each end in the width direction of the steel strip.
X: Distance between the intersection of the steel strip and the center line of the gas jet from the first nozzle and the intersection of the steel strip and the center line of the gas jet from the second nozzle B ₁ : Distance of the first nozzle Slit gap B ₂ : Slit gap of the second nozzle θ ₁ : Angle between the center line of the gas jet from the first nozzle and the horizontal θ ₂ : Angle between the center line of the gas jet from the second nozzle and the horizontal D ₁ : Distance between the slit center of the first nozzle and the steel strip D ₂ : Distance between the slit center of the second nozzle and the steel strip H ₁ : Height of the slit center of the first nozzle H ₂ : The second Height of the slit center of the two nozzles D _min1 : Distance between the lowest end of the tip of the first nozzle and the steel strip D _min2 : Distance between the lowest end of the tip of the second nozzle and the steel strip H _min1 : Height of the lowest end of the tip of the first nozzle H _min2 : Height of the lowest end of the tip of the second nozzle The first nozzle and the second nozzle are
(A) The direction of gas injection from each of the first nozzle and the second nozzle is downward with respect to a horizontal plane, and the angle difference between the direction of gas injection from each of the first nozzle and the second nozzle with respect to the horizontal plane is 8. ° or less , and
(B) a first projection line and a second projection line obtained by projecting the slit center lines of the first nozzle and the second nozzle onto the surface of the steel strip intersect on the width direction center line of the steel strip; And, the first projection line and the second projection line are vertically opposite directions and equiangular with respect to the horizontal line ,
Continuous hot dip metal plating equipment according to claim 7 or 8. 10. The continuous hot dip metal plating facility according to claim 9, wherein the angle difference is 4[deg.] or less. 10. The continuous hot dip metal plating facility of claim 9, wherein said angular difference is 0[deg.].

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