JP2011252180A - Method of manufacturing hot dip metal coated steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of stably manufacturing a hot dip metal coated steel strip having excellent surface quality by providing a nozzle member for jetting a curtain gas from the outside of the steel strip end part toward the steel strip end part to reduce production of splash and to prevent edge over coat and preventing the deposition of the plating metal to the nozzle member from which the gas is jetted.SOLUTION: In the method of manufacturing the hot dip metal coated steel strip by which the thickness of the deposited metal is controlled by blowing the gas from a gas wiping nozzle 1 oppositely arranged on both surface across the steel strip on the surface of the steel strip continuously pulled up from a hot melt metal plating bath, the curtain gas is jetted from the outside of each steel strip end part toward the steel strip end part in the jetting height position of the wiping gas.

Description

  The present invention relates to a method for manufacturing a molten metal-plated steel strip that can reduce splash scattering and prevent edge overcoat in a hot-dip plating process.

  In a continuous hot dipping process or the like, as shown in FIG. 5, the steel strip S is generally immersed in a plating bath 8 filled with molten metal and the direction is changed by the sink roll 7. After the step of pulling upward, the steel strip width provided facing the steel strip S so that the molten metal adhering to the steel strip surface has a predetermined plating thickness uniformly in the plate width direction and the plate longitudinal direction. There is provided a gas wiping device for controlling the amount of molten metal attached (plating amount) by ejecting pressurized gas from the gas wiping nozzle 1 extending in the direction onto the steel strip to squeeze out excess molten metal. Yes.

  The gas wiping nozzle 1 is usually longer than the width of the steel strip, that is, extending beyond the width end of the steel strip S, in order to cope with various steel strip widths and at the same time to shift in the width direction when the steel strip is pulled up. ing. In such a gas wiping device, an edge overcoat where the plating thickness at the end of the steel strip is thicker than that at the center because the jet impinging on the end of the steel strip faces slightly outside and the impact force decreases. Or a defect caused by so-called splash, in which molten metal falling below the steel strip scatters due to the turbulence of the jet impinging on the steel strip S, causes a deterioration in the surface quality of the steel strip.

  Moreover, in order to increase the production amount in the continuous process, the steel plate passing speed may be increased. However, in the case of controlling the coating amount by the gas wiping method in the continuous hot dipping process, due to the viscosity of the molten metal, As the line speed increases, the initial adhesion amount immediately after passing through the plating bath of the steel strip increases, so to control the plating adhesion amount within a certain range, the wiping gas pressure must be set to a higher pressure, As a result, the splash is greatly increased and good surface quality cannot be maintained.

  In order to solve the above problems, a method of providing a gas nozzle in the vicinity of both ends of the steel strip, or a baffle plate positioned on the extension surface of both ends of the steel strip to provide a gas jet between gas jet nozzles on both sides of the steel strip. A method for blocking a collision is disclosed as follows.

  In Patent Document 1, as shown in FIG. 6, wiping of excess molten metal adhering to the end of the steel strip is performed by the side nozzle 12 provided on the steel strip S width direction extension line below the main nozzle (wiping nozzle) 11. A method of performing gas wiping by the main nozzle 11 after performing the above is disclosed.

  In Patent Document 2, as shown in FIG. 7, in order to prevent the molten metal from adhering to the baffle plate 30 provided on the surface extending in the width direction of the steel strip S, the steel strip side end 31 of the baffle plate 30 faces downward. The method of providing the gas nozzle 32, the method of providing a cooling part (not shown) inside the steel strip side end 31, the method of configuring the steel strip side end 31 with a material having low wettability with molten metal, or A method of combining the above methods is disclosed.

  In Patent Document 3, as shown in FIG. 8, an inclined guide 42 that changes the flow of the injection gas from the wiping nozzle 41 near the end of the steel strip inward is provided at the bottom of the steel strip side corner of the baffle plate 40. A method for preventing the generation of noise and splash is disclosed.

  In Patent Document 4, as shown in FIG. 9, an auxiliary nozzle 52 provided at the same height as the gas wiping nozzle 51 and tapered outward at an acute angle toward the tip is referred to by the gas wiping nozzle 51. The high-pressure jet 54 is jetted toward the plate width direction central portion of the steel strip S, and the jet flow 53 from the gas wiping nozzle 51 is changed to a diverted flow 55 toward the plate width direction end of the steel strip S. A method for preventing edge overcoats is disclosed.

JP-A-6-158261 JP-A-9-41114 JP 2003-321756 A Japanese Patent Laid-Open No. 10-183325

  However, in the method disclosed in Patent Document 1, the edge overcoat is reduced, but the gas flow injected from the obliquely inward side nozzle 12 reaches the steel strip S and is injected from the main nozzle 11. Since the point which collides with the steel strip S is separated, there is a problem that a splash is generated by the gas of the side nozzle 12 in addition to the splash generated by the main nozzle 11 and a lot of splash defects are generated. Further, the splash generated in the vicinity of the wiping nozzle 11 injection port accumulates in the shape of icicles on the side nozzle 12 and adheres to the steel strip, so that stable operation was not possible.

  In the method disclosed in Patent Document 2, although the splash does not easily adhere to the baffle plate 30, there is a limit in bringing the baffle plate 30 close to the steel strip for installing the gas nozzle 32, and the splash and edge overcoat are reduced. The effect was limited.

  In the method disclosed in Patent Document 3, as in Patent Document 1, even if an inward gas flow is generated, the gas turbulence increases, so the occurrence of splash is large, and the splash accumulated on the upper portion of the inclined guide 42 is generated. There was a problem that adhered to the steel strip and caused granular surface defects.

  In the method disclosed in Patent Document 4, since a jet having a pressure higher than that of gas wiping is injected toward the end of the steel strip, splash generated at the end of the steel strip is scattered in the direction of the steel strip and reattached to the steel strip. However, there is a problem that a splash defect occurs.

  The present invention solves the above-mentioned problems and reduces the occurrence of splash and prevents edge overcoat by providing a nozzle member that injects curtain gas from the steel strip end to the steel strip end. It is another object of the present invention to prevent the plating metal from adhering to the nozzle member for injecting the gas and to stably manufacture a molten metal plated steel strip having excellent surface quality.

  Means of the present invention for solving the above-mentioned problems are as follows.

  (1) Molten metal-plated steel that controls the thickness of the deposited metal by blowing a gas from a gas wiping nozzle disposed opposite to both sides of the steel strip across the surface of the steel strip that is continuously pulled up from the molten metal plating bath In the manufacturing method of a strip | belt, a curtain gas is injected toward the steel strip end part from the steel strip end part outer side at the wiping gas injection height position, The manufacturing method of the hot-dip metal plating steel strip characterized by the above-mentioned.

  (2) A slit nozzle having a slit-like gas injection port in the longitudinal direction of the steel strip is arranged at the wiping gas injection height position on the surface extending in the width direction of the steel strip, and curtain gas is injected toward the end of the steel strip. (1) The manufacturing method of the hot-dip metal-plated steel strip according to (1).

  (3) The gas injection port of the slit nozzle is arranged such that the upper end of the gas injection port is higher than the upper end of the injection port of the gas wiping nozzle and the lower end of the gas injection port is lower than the lower end of the injection port of the gas wiping nozzle. (2) The manufacturing method of the hot-dip metal-plated steel strip according to (2).

  (4) The steel strip thickness direction width of the gas injection port of the slit nozzle is equal to or greater than the maximum plate thickness of the steel strip to be produced. The molten metal plated steel strip according to (2) or (3) Production method.

  (5) The molten metal plated steel according to any one of (2) to (4), wherein the gas pressure at the gas injection port of the slit nozzle is 10 to 50% of the gas pressure of the gas wiping nozzle. Manufacturing method of the belt.

  (6) The melting according to any one of (2) to (5), wherein the slit nozzle is incorporated in a baffle plate installed between opposing gas wiping nozzles on the surface extending in the width direction of the steel strip. A method for producing a metal-plated steel strip.

  (7) The slit nozzle is attached to a side surface of a baffle plate installed between opposing gas wiping nozzles on the steel strip width direction extended surface, (2) to (5), A method for producing a molten metal-plated steel strip.

  Here, the curtain gas refers to a jet having a shape in which the cross-sectional shape of the jet in the gas discharge portion has a shape with a small width in the steel strip thickness direction and a large length in the longitudinal direction of the steel strip.

  According to the present invention, at the height position of the gas wiping nozzle, by spraying curtain gas from the outside of the steel strip end toward the steel strip end, not only the normal steel strip passing speed but also the steel strip passing plate Even when the speed is increased, the edge overcoat is applied by the same action as reducing the edge splash by suppressing the wiping gas flow from the steel strip center to the steel strip edge and making the baffle plate close to the steel strip. In addition, since it is possible to prevent the plating metal from adhering to the nozzle member that injects the curtain gas, it is possible to stably manufacture a molten metal plated steel strip having excellent surface quality.

It is a figure which shows embodiment of the gas wiping apparatus used for implementation of this invention, and is a schematic perspective view which shows the steel strip edge part vicinity part of a gas wiping nozzle. It is a longitudinal cross-sectional view which shows embodiment of the slit nozzle of the gas wiping apparatus used for implementation of this invention. It is a figure explaining the effect | action of the slit nozzle of the gas wiping apparatus used for implementation of this invention, and shows the flow of the wiping gas of steel strip edge vicinity when it sees from the steel strip front. It is a figure explaining the effect | action of the slit nozzle of the gas wiping apparatus used for implementation of this invention, and shows the flow of the wiping gas of steel strip edge vicinity when it sees from gas wiping apparatus upper direction. It is a schematic side view of the manufacturing apparatus of a general continuous molten metal plating steel strip. It is a schematic perspective view which shows the principal part of the gas wiping apparatus used by patent document 1. The baffle plate used by patent document 2 is shown, (a) is a side view, (b) is a top view. It is a schematic perspective view which shows the principal part of the gas wiping apparatus used by patent document 3. It is a schematic plan view when the principal part of the gas wiping apparatus used by patent document 4 is shown and it sees from gas wiping apparatus upper direction.

  In the method for producing a molten metal-plated steel strip of the present invention, the metal adhered to the surface of the steel strip that is continuously pulled up from the molten metal plating bath by blowing gas from a gas wiping nozzle disposed opposite to both sides of the steel strip. To control the thickness. At that time, curtain gas is injected from the outer side of each steel strip end toward the end of the steel strip at the wiping gas injection height position.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view showing an embodiment of a gas wiping device used in the practice of the present invention and showing a portion near one end of a steel strip of a gas wiping nozzle. In FIG. 1, 1 is a gas wiping nozzle, 2 is a slit nozzle, and S is a steel strip. The gas wiping nozzle 1 is oppositely disposed on both sides of the steel strip S, and the slit nozzle 2 has the same external shape as the baffle plate of the prior art, has a substantially plate shape, on the surface extending in the steel strip width direction. It arrange | positions at intervals with a steel strip edge part, and has a gas injection port in a steel strip side edge part.

  FIG. 2 is a view showing an embodiment of the structure of the slit nozzle 2, and is a longitudinal sectional view of the steel strip width direction extension surface. The one-dot chain line in the figure is the injection port position of the gas wiping nozzle (the injection height position of the wiping gas, the height position of the slit gap center). The slit nozzle 2 is provided with a gas flow path 3 extending from the end on the side opposite to the steel strip to the end on the steel strip side. The cross section of the gas flow path 3 has a circular end at the anti-steel strip side, and the cross-sectional shape gradually changes from a circular shape to a vertically long rectangle from the anti-steel strip end to the steel strip end. The band side end is a rectangular opening (gas injection port) having a slit in the longitudinal direction of the steel band. A gas introduction pipe 4 is connected to the end of the gas flow path 3 on the side opposite to the steel strip to introduce gas, and the curtain is directed from the injection port at the end of the steel strip toward the end of the strip at the injection height position of the wiping gas. Inject gas. At the injection height position of the wiping gas, the wiping gases collide with each other.

  The operation of the slit nozzle of the present invention will be described with reference to FIGS. FIG. 3 is a view of the main gas flow near the end of the steel strip as viewed from the front of the steel strip surface, where (a) uses a baffle plate and (b) uses the slit nozzle of the present invention. Is the case. FIG. 4 is a view of the main gas flow near the end of the steel strip as viewed from above the gas wiping device. FIG. 4A shows a case where a baffle plate is used, and FIG. 4B shows a case where the slit nozzle of the present invention is used. Is the case.

  It is known that when the baffle plate is brought close to the end of the steel strip, the effect of reducing edge splash and edge overcoat is excellent. However, if the baffle plate is too close to the end of the steel strip, the splash adheres to the baffle plate, and the effect of reducing edge splash and edge overcoat cannot be stably exhibited. Conventionally, in order to prevent the splash from adhering to the baffle plate, the baffle plate is disposed with a gap of about 10 to 20 mm from the steel strip. In such an arrangement state, the wiping gas is likely to flow toward the gap between the steel strip S and the baffle plate 20, and at the end of the steel strip, as shown in FIG. A heading flow occurs. The splashed plated metal is scattered on the flow and adheres to the baffle plate 20. Further, the gas flow near the end of the steel strip becomes very disturbed, and the collision pressure of the wiping gas is lowered, so that edge overcoat is generated.

  In the slit nozzle of the present invention, when the curtain gas is injected from the gas injection port of the slit nozzle 2 toward the steel strip end portion, the steel strip width direction extension surface between the gas injection port of the slit nozzle 2 and the steel strip end portion is formed. A curtain-like jet is formed, as if the plate is in contact with the steel strip, that is, the steel strip surface is extended in the width direction. As a result, the flow of the wiping gas near the end of the steel strip flows in the vertical direction as in the central portion of the steel strip (FIG. 3B), and the steel strip width direction component of the gas flow decreases (FIG. 4B). )). Splash and edge overcoat are reduced by reducing the steel strip width direction component. Furthermore, since the scattering of the plating metal from the steel strip end to the outside is reduced, the adhesion of the plating metal to the slit nozzle is also suppressed.

  In order to obtain the above effect, the position (vertical position) of the gas injection port of the slit nozzle is such that the upper end of the gas injection port is higher than the upper end of the injection port of the gas wiping nozzle, and the lower end of the gas injection port is lower than that of the gas wiping nozzle. It is preferable that the upper end of the gas injection port is 5 mm or more higher than the upper end of the injection port of the gas wiping nozzle, and the lower end of the gas injection port is lower than the lower end of the injection port of the gas wiping nozzle. More preferably, it is arranged to be 5 mm or lower. If the vertical positions of the upper and lower ends of the gas injection port of the slit nozzle are too far from the injection port of the gas wiping nozzle, a flow in the width direction of the steel strip occurs after a collision, and the above effect of the present invention is impaired. Since the location where the splash is generated is below the collision position between the wiping gases, the upper end of the gas injection port of the slit nozzle is within 20 mm from the upper end of the injection port of the gas wiping nozzle, and the lower end of the gas injection port of the slit nozzle is the gas wiping nozzle. It is preferable to make it within 30 mm from the lower end of the nozzle.

  The width in the steel strip thickness direction of the gas injection port of the slit nozzle is preferably equal to or greater than the maximum thickness of the steel strip to be produced from the point of manifesting the effect of extending the steel strip in the width direction. When the distance between the slits is about 10 mm at a minimum, the thickness in the steel strip thickness direction of the slit nozzle is about 6 mm, and is preferably 5 mm or less. The position of the gas injection port of the slit nozzle in the steel strip thickness direction is preferably installed so as to be located on the extended surface in the steel strip width direction.

  When the gas injection pressure from the gas injection port of the slit nozzle is less than 10% of the gas injection pressure of the gas wiping nozzle, the edge splash suppression effect cannot be obtained, and when it exceeds 50%, the turbulence of the wiping gas flow is increased. Let the splash increase. Therefore, the gas injection pressure from the gas injection port of the slit nozzle is preferably 10 to 50% of the gas injection pressure of the gas wiping nozzle.

  Since the slit nozzle of the present invention has a plate-like outer shape and dimensions similar to those of a normal baffle plate, it can be configured to be used in place of the baffle plate. Moreover, it is good also as a structure which incorporated the slit nozzle which injects curtain gas toward a steel strip edge part in a baffle plate. In addition, a slit nozzle of the present invention may be prepared separately from a normal baffle plate, and a slit nozzle for injecting curtain gas toward the end of the steel strip may be attached to the side surface of the baffle plate.

  As described above, conventionally, it has been necessary to control the distance very severely so that the distance between the baffle plate and the steel strip end is within a range of 10 to 20 mm. In the gas wiping method of the present invention, even when the distance between the slit nozzle and the steel strip end portion is increased, the splash preventing effect and the edge overcoat preventing effect are exhibited, and the distance between the slit nozzle and the steel strip end portion is reduced. In addition, since the splash adhesion to the slit nozzle is suppressed, the distance control between the slit nozzle and the steel strip does not need to be performed as severe as the conventional baffle plate. For example, in this invention, what is necessary is just to control the space | interval of a slit nozzle and a steel strip edge part so that it may exist in the range of 5-40 mm.

  In order to clarify the effect of the slit nozzle of the present invention and the preferred conditions of the gas injection pressure, the gas wiping apparatus shown in FIG. 1 is installed in a continuous hot dip galvanizing line, and the gas injection pressure of the slit nozzle and the steel strip to the slit The nozzle distance was changed variously and the production experiment of the hot dip galvanized steel strip was conducted. The slit nozzle is bolted to the end of the frame extended from the servo motor position control device provided at the top of both ends of the gas wiping nozzle, so that the distance from the steel strip can be controlled easily, and the slit nozzle is attached to the baffle plate. The case where it was used independently by the alternative (Invention Examples 1 to 8) and the case where it was installed along the baffle plate (Invention Examples 9 and 10) were carried out. The gas supplied to the slit nozzle is air at room temperature and branches into two lines near the plating pot. Each pipe is equipped with a pressure gauge and a manual adjustment valve, and connected to the slit nozzles at both ends of the steel strip to arbitrarily set the injection pressure. It became possible to set. Further, the correspondence relationship between the display pressure in the adjustment valve and the gas injection pressure from the actual slit nozzle was previously measured offline.

  The slit nozzle of the present invention is a rectangular parallelepiped having outer dimensions of a steel strip traveling direction length of 100 mm, a steel strip width direction length of 400 mm, and a thickness of 5 mm, and the slit size at the end of the steel strip (the dimension of the gas injection port) is: The steel strip thickness direction was 2 mm and the steel strip longitudinal direction was 30 mm. The gas introduction pipe on the side of the anti-steel strip has a circular shape with an inner diameter of 10 mm, and a pipe with a different diameter of 100 mm with a cross-sectional shape gradually changed from a 10 mm circle to a rectangular cross section of the steel strip thickness direction 4 mm × steel strip longitudinal direction 15 mm ( In this different diameter pipe, the dimension in the steel strip thickness direction on the anti-steel strip side is thicker than the thickness of the slit nozzle body, but the thick part is above the wiping gas injection height position. )) And a cross section of the flow path is provided so that there is no sudden expansion / contraction to the gas injection port. With respect to the wiping gas injection height position (collision position between wiping gases), the upper end of the gas injection port of the slit nozzle is arranged 10 mm above and the lower end of the gas injection port is arranged 20 mm below.

  As comparative examples, the baffle plate described in Patent Document 2 (Comparative Examples 1 and 2), the inclined guide described in Patent Document 3 (Comparative Examples 3 and 4), and the auxiliary nozzle described in Patent Document 4 (Comparative Examples 5 and 6) ) Was used to conduct a production experiment of a hot-dip galvanized steel strip. The baffle plate of the comparative example had a height of 50 mm, a width of 400 mm, and a thickness of 5 mm, and the wiping gas collision position was 30 mm from the upper end of the baffle plate.

  The manufacturing conditions are a gas wiping nozzle slit gap of 0.9 mm, a gas wiping nozzle-steel strip distance of 8 mm, a nozzle height from a molten zinc bath of 600 mm, a molten zinc bath temperature of 465 ° C., and a steel strip size of 0.8 mm. The thickness was set to 1.2 m width. Table 1 shows the other manufacturing conditions and the amount of plating adhesion, the difference in the amount of plating adhesion (steel plate edge 100 mm-center), the amount of splash, the slit nozzle, and the zinc adhesion to the baffle plate. The splash generation amount is a ratio of the steel strip length determined to have a splash defect in the inspection process to the steel strip length passed under each manufacturing condition, and includes a slight splash defect that does not cause a problem in practice.

Zinc adhesion to the slit nozzle and the baffle plate was evaluated by visually observing the adhesion state of the splash (zinc powder) to the slit nozzle and the baffle plate as follows.
○: No splash adhesion △: Splash adhesion is infrequent or repeats adhesion and peeling ×: Splash adhesion is always present

  Inventive Examples 1 to 5 confirm the influence of the gas injection pressure injected from the slit nozzle toward the steel strip end, and 2 to 40 kPa and 4 to 80% of the gas injection pressure of the gas wiping nozzle are set. Pressure was used. Inventive Examples 1 to 5 are all compared to Comparative Examples 1, 3, and 5 under the same wiping conditions, the splash occurrence rate, edge overcoat (edge-center adhesion amount difference), slit nozzle, and zinc adhesion to the baffle plate. Good results were obtained in this point, and among them, better results were obtained in Invention Examples 2 to 4 in which the gas injection pressure of the slit nozzle was in the range of 10 to 50% of the gas injection pressure of the gas wiping nozzle. Obtained.

  Inventive Examples 6 to 8 confirmed the influence of the distance between the slit nozzle and the steel strip, and it was found that at any distance, a high-quality product could be manufactured more stably than Comparative Examples 1, 3, and 5. . In addition, the closer the slit nozzle was to the steel strip, the better the results.

  Invention Example 9 is a case where another slit nozzle having the same gas injection port as the slit nozzles of Invention Examples 1 to 8 is set on a conventional baffle plate (the thickness in the thickness direction of the combined baffle plate and slit nozzle is 10 mm) ), It was found that the performance was equivalent to that of Invention Example 3.

  Inventive Example 10 is an example of high productivity operation using the slit nozzle of Inventive Example 9 to increase the plate passing speed to 200 m / min. Comparative Examples 2, 4 and 6 according to the prior art have a plate passing speed of 200 m / min. While stable production was impossible with min, Invention Example 10 was able to stably produce a higher quality product than Comparative Examples 1, 3, and 5 according to the prior art with a plate passing speed of 150 m / min. It was.

  INDUSTRIAL APPLICABILITY The present invention can be used as a method for producing a molten metal plated steel strip that can reduce splash scattering and prevent edge overcoat.

S Steel strip 1 Gas wiping nozzle 2 Slit nozzle 3 Gas flow path 4 Gas introduction pipe 7 Sink roll 8 Plating bath 11 Main nozzle (wiping nozzle)
12 Side nozzles 20, 30 Baffle plate 31 Steel strip side end 32 Gas nozzle 40 Baffle plate 41 Wiping nozzle 42 Inclined guide 43 Molten metal bath (plating bath)
51 Gas wiping nozzle 52 Auxiliary nozzle 53 Jet flow from gas wiping nozzle 54 Jet flow from auxiliary nozzle 55

Claims (7)

Manufacture of molten metal-plated steel strip that controls the thickness of the deposited metal by blowing gas from the gas wiping nozzle that is placed opposite to both sides of the steel strip across the surface of the steel strip that is continuously pulled up from the molten metal plating bath A method for producing a molten metal-plated steel strip, characterized in that a curtain gas is jetted from the outer end of each steel strip toward the end of the steel strip at a wiping gas injection height position. A slit nozzle having a slit-like gas injection port in the longitudinal direction of the steel strip is arranged at the wiping gas injection height position on the surface extending in the width direction of the steel strip, and the curtain gas is jetted toward the end of the steel strip. The manufacturing method of the hot-dip metal plating steel strip of Claim 1 characterized by the above-mentioned. The gas injection port of the slit nozzle is arranged such that the upper end of the gas injection port is higher than the upper end of the injection port of the gas wiping nozzle and the lower end of the gas injection port is lower than the lower end of the injection port of the gas wiping nozzle. The manufacturing method of the hot-dip metal-plated steel strip of Claim 2 characterized by the above-mentioned. 4. The method for producing a hot-dip metal-plated steel strip according to claim 2, wherein the width in the steel strip thickness direction of the gas injection port of the slit nozzle is equal to or greater than the maximum thickness of the steel strip to be produced. The method for producing a molten metal-plated steel strip according to any one of claims 2 to 4, wherein a gas pressure at a gas injection port of the slit nozzle is 10 to 50% of a gas pressure of the gas wiping nozzle. . The molten metal-plated steel strip according to any one of claims 2 to 5, wherein the slit nozzle is incorporated in a baffle plate installed between opposing gas wiping nozzles on an extended surface in the steel strip width direction. Production method. The molten metal-plated steel strip according to any one of claims 2 to 5, wherein the slit nozzle is attached to a side surface of a baffle plate installed between opposing gas wiping nozzles on an extended surface in the steel strip width direction. Manufacturing method.

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