JP2006070283A - Gas wiping nozzle, and manufacturing device of hot-dip plating metal band - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact, economical and high-performance gas wiping nozzle capable of suppressing generation of turbulence vortexes. <P>SOLUTION: The gas wiping nozzle 1 comprises an upper lip 2 and a lower lip 3 which are assembled facing each other so as to form a nozzle port 4 to spout wiping gas therefrom, and a plurality of small grooves are formed in an inclined outer surface A of the upper lip 2 and an inclined outer surface A' of the lower lip 3. By forming the small grooves, associated flows 51, 51' can be smoothly advanced in the wiping gas spouting direction to suppress generation of turbulence vortexes 52, 52'. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas wiping nozzle for adjusting the amount of adhesion of molten metal and enabling uniform adhesion in the manufacturing process of a hot-dip metal strip.

  As a method for continuously plating a metal band such as a steel band, a hot dipping method in which the metal band is immersed in a molten metal such as zinc or aluminum and the surface of the metal band is plated is known.

The outline of the hot dipping method is as follows, for example.
First, the rolled and cleaned metal strip is subjected to an annealing process while removing the surface oxide film in an annealing furnace. Thereafter, the metal strip is cooled to approximately the same as the temperature of the molten metal, wound around a sink roll provided in the molten metal bath, and immersed by passing through the molten metal in a substantially V-shaped path, Molten metal is deposited on the surface. Then, the metal strip drawn from the molten metal bath is sprayed with wiping gas blown by a gas wiping nozzle disposed so as to sandwich the metal strip from both the front and back sides of the metal strip, and an excessive amount The molten metal is wiped off and the amount of metal adhesion is adjusted.

  This hot dip plating method has many features such as the ability to produce a plated metal strip at a low cost and the ability to easily produce a metal strip for thick film plating when compared to other electroplating methods. Yes.

  By the way, in order to produce a plated metal strip at a high speed by the above hot dipping method, it is necessary to improve the ability to wipe off excess molten metal, that is, the wiping ability, and increase the amount of molten metal that can be wiped per unit time. Generally, in order to improve the wiping capability, it is only necessary to increase the pressure of the jet gas. In this case, turbulent vortices are likely to occur, and the airflow is disturbed, so splash (abnormal splatter of molten metal to be wiped off) Often occurs, resulting in deterioration of the quality of the plated metal strip to be produced.

Therefore, as a means for solving the above problem, a technique has been proposed in which a substream nozzle is provided in addition to the mainstream nozzle that ejects the wiping gas (for example, Patent Document 1, Patent Document 2, etc.). However, this sub-flow nozzle has the following technical problems (1) and (2).
(1) Since the substream nozzle is provided in addition to the conventional mainstream nozzle, the nozzle itself is increased in size.
(2) Usually, since the pressures of the main flow nozzle and the sub flow nozzle need to be adjusted individually, the cost becomes high and the control system and operation become complicated.

On the other hand, it is effective to reduce the flow resistance of the wiping gas in order to suppress the generation and growth of turbulent vortices that contribute to the splash. From such a viewpoint, for example, a method of reducing the flow resistance of the wiping gas by radiating a flame to the tip of the wiping nozzle, surrounding the wiping gas with a high temperature gas, and reducing the density around the wiping gas is proposed. (For example, refer to Patent Document 3). However, this method requires a burner and a fuel supply system for generating a flame, which not only complicates the nozzle structure but also concerns the influence of the flame on the quality of the metal strip. I can't say that.
JP-A-1-230758 (FIG. 2 etc.) JP-A-10-204599 (FIG. 5 etc.) JP 2002-348650 A (FIG. 1 etc.)

  The present invention has been made in view of the above circumstances, and can produce a high-quality plated metal strip at a high speed without causing splash even at a high jet gas pressure, and is compact and economical. An object of the present invention is to provide a high performance gas wiping nozzle.

In order to solve the above-described problem, the first invention is a gas wiping nozzle that blows and wipes off excess molten metal adhering to the metal band when the hot-dipped metal band is manufactured,
While forming a slit-like nozzle port with the width direction of the metal strip as the longitudinal direction,
There is provided a gas wiping nozzle characterized by having a groove on a part or all of the outer surface of a nozzle body.

  In the gas wiping nozzle according to the first aspect of the present invention, it is preferable that the groove portion is formed on an inclined surface and / or a parallel surface that forms an acute angle with the gas blowing direction toward the nozzle port.

Further, the second invention is a gas wiping nozzle that blows away excess molten metal adhering to the metal band by blowing gas when manufacturing the hot-dipped metal band,
While forming a slit-like nozzle port with the width direction of the metal strip as the longitudinal direction,
There is provided a gas wiping nozzle characterized by having a groove in part or all of an inner surface of a nozzle body.

  In the gas wiping nozzle according to the second aspect of the present invention, it is preferable that the groove is formed on an inclined surface and / or a parallel plane parallel to the gas blowing direction toward the nozzle port.

Moreover, the third invention is a gas wiping nozzle for wiping off excess molten metal adhering to the metal band by blowing gas when manufacturing the hot-dipped metal band,
While forming a slit-like nozzle port with the width direction of the metal strip as the longitudinal direction,
There is provided a gas wiping nozzle characterized by having a groove in part or all of the outer surface of the nozzle body and part or all of the inner surface of the nozzle body.

  In the gas wiping nozzle of the third invention, the groove is formed on an outer surface and an inner surface of the nozzle body on an inclined surface and / or a parallel surface that forms an acute angle with the gas blowing direction toward the nozzle port. Is preferred.

Furthermore, in the gas wiping nozzles according to the first to third inventions, it is preferable that the narrow grooves constituting the groove portions are formed in parallel with the gas blowing direction. Alternatively, the narrow groove constituting the groove part may be formed to meander, and the angle formed between the tangential direction and the gas blowing direction is preferably 45 degrees or less.
Moreover, it is preferable that the angle of the top part of the peak of the fine groove which comprises the said groove part is 90 degrees or less.
Moreover, it is preferable that the height of the peak of the narrow groove which comprises the said groove part is 1 mm or less.

  According to a fourth aspect of the present invention, there is provided a hot dipped metal strip manufacturing apparatus comprising any one of the gas wiping nozzles.

In the gas wiping nozzle of the present invention described above, the flow resistance can be reduced because the generation and growth of turbulent vortices are suppressed by providing the groove on part or all of the outer surface and / or inner surface of the nozzle body.
Further, the flow resistance is further reduced by meandering the narrow groove constituting the groove portion with respect to the blowing direction of the wiping gas, for example, providing a zigzag shape or a sine wave shape, and vibrating the gas in a direction perpendicular to the blowing direction. An effect is obtained.

Therefore, according to the present invention, a compact and inexpensive high-performance gas wiping nozzle can be provided.
That is, the gas wiping nozzle of the present invention does not need to increase the size of the nozzle because only the streaks are formed on the outer surface and / or the inner surface of the nozzle body. Moreover, since the wiping gas supply system is only the mainstream nozzle, the control system and operation are not complicated. As a result, excellent wiping performance can be obtained without increasing the size and complication of operation as in the case of providing a substream nozzle. Therefore, by using the gas wiping nozzle of the present invention, it is possible to produce a high-quality plated metal strip at high speed without causing splash even at a high jet gas pressure.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a hot dipped metal strip manufacturing apparatus to which the gas wiping nozzle of the present invention can be applied. Further, FIG. 2 shows details of a broken line portion X (around the molten metal bath 72) in FIG.

  The metal strip 70 that has been rolled in the cold rolling process, which is the previous step, and whose surface has been cleaned in the subsequent cleaning process, is transported to the hot-dipped metal strip manufacturing apparatus 100 and annealed in a non-oxidizing or reducing atmosphere. In the furnace 71, the surface oxide film is removed and an annealing process is performed. Thereafter, the molten metal is cooled to approximately the same temperature as the molten metal and guided into the molten metal bath 72.

  The metal strip 70 is drawn into the molten metal bath 72 through a cylindrical portion called a snout 77 that is maintained in a non-oxidizing atmosphere. In the molten metal bath 72, the sheet passing direction is changed by the sink roll 78 which is a direction changing roll, and then the molten metal bath 72 is passed through the collect roll 79b and the stabilizing roll 79a arranged in the bath. Pulled out.

  As described above, in the molten metal bath 72, the molten metal is adhered to the surface of the molten metal bath 72 by passing the metal strip 70 while being immersed in the molten metal. The metal strip 70 drawn out from the molten metal bath 72 passes between a pair of gas wipers 73 and 73 disposed opposite to each other so as to sandwich the metal strip 70 from both sides at the subsequent stage of the molten metal bath 72. , Wiping gas is blown. With this gas, excess molten metal adhering to the metal strip 70 is wiped off, and the amount of metal adhesion is adjusted.

  Subsequently, the metal strip 70 is reheated by using the alloying furnace 74 as necessary, and an alloying process for producing a homogeneous alloy layer is performed. Next, after passing through the quenching zone 75, the metal strip 70 is subjected to special rust prevention treatment and corrosion resistance treatment in the chemical conversion treatment section 76, wound around a coil and shipped.

Next, the structure of the gas wiping nozzle constituting the gas wiper 73 in the hot dip metal strip manufacturing apparatus 100 will be described with reference to FIGS.
FIG. 3 is a diagram showing a schematic configuration of the gas wiping nozzle 1 according to the first embodiment of the present invention. The gas wiping nozzle 1 includes an upper lip 2 and a lower lip 3 that are combined so as to face each other. The tip portions of the upper lip 2 and the lower lip 3 are spaced apart at a predetermined interval (nozzle gap), and form a nozzle port 4 through which wiping gas is blown. The nozzle port 4 is formed in a slit shape whose longitudinal direction is the width direction of the metal strip 70. In FIG. 3, reference numeral 5 denotes a wiping gas circulation portion that is continuous with the nozzle port 4.

  In the present embodiment, a plurality of fine grooves (grooves) as groove portions are formed on the inclined outer surface A of the upper lip 2 and the inclined outer surface A ′ of the lower lip 3 which are combined in a sharp shape in cross section from the base end side to the distal end side. 3 is omitted). The tip end side of the inclined outer surface A of the upper lip 2 and the inclined outer surface A ′ of the lower lip 3 is a portion that comes into contact with the accompanying flow generated with the flow of the wiping gas that is strongly blown from the nozzle port 4. .

  Specific examples of the narrow grooves are shown in FIGS. 4 is an enlarged view of the inclined outer surface A of the upper lip 2 as viewed from the line of sight orthogonal to the inclined outer surface A (that is, the direction indicated by the white arrow in FIG. 3). In the figure, the wiping gas blowing direction indicated by the arrow is the direction toward the tip of the gas wiping nozzle 1. A similar narrow groove is also formed on the inclined outer surface A ′ of the lower lip 3.

  In the example of FIG. 4, a plurality of narrow grooves 10 are formed in parallel to the wiping gas blowing direction. These narrow grooves 10 are composed of peaks 10a and valleys 10b. Providing the narrow grooves 10 parallel to the wiping gas blowing direction on the inclined outer surfaces A and A ′ of the upper lip 2 and the lower lip 3 which are in contact with the accompanying flow, as described later, generates turbulent vortices. It is effective in suppressing growth and reducing flow resistance.

FIG. 5 is a drawing showing a cross-sectional structure of the narrow groove 10. If the angle α formed by the top of the crest 10a of the narrow groove 10 exceeds 90 degrees, the effect of suppressing turbulent vortex is reduced, so the angle α is preferably 90 degrees or less.
Further, the height H of the mountain needs to be 1 mm or less in the case of an object having a high Reynolds number such as a gas wiping nozzle, and it is preferable that the height H is generally less than 10 to 500 μm depending on conditions. It is desirable that H = 10 to 200 μm.

6 and 7 are examples in which the narrow grooves are formed so as to meander rather than linearly. Similar to FIG. 4, the inclined outer surface A of the upper lip 2 is perpendicular to the inclined outer surface A. It is the enlarged view seen in. In FIG. 6, the zigzag narrow groove 11 is formed so that the tangential direction of the narrow groove 11 forms an angle of θ ₁ and θ _{2 at} the maximum with the blowing direction of the wiping gas. Here, θ ₁ and θ ₂ may be the same or different, but either angle is preferably 45 degrees or less, and more preferably 20 degrees or less in order to reduce the flow resistance.

FIG. 7 shows an example in which sinusoidal narrow grooves 12 are formed. In this case as well, the angles formed by the tangential direction of the narrow grooves 12 and the blowing direction of the wiping gas are θ ₃ and θ ₄ at the maximum. In FIG. 7, θ ₃ and θ ₄ have the same angle, but a waveform may be formed such that θ ₃ and θ ₄ have different angles. In order to reduce the flow resistance, θ ₃ and θ ₄ are preferably 45 degrees or less, and more preferably 20 degrees or less.

  As described above, the narrow grooves are meandered so that the tangential direction thereof is at a predetermined angle with respect to the wiping gas blowing direction, so that the turbulent vortex near the surface appears as if by the surface vibration and the straight movement of the flow. As a result, the generation and growth of turbulent vortices are effectively suppressed, so that an excellent flow resistance reduction effect can be obtained. In addition, the height of the peak which comprises the narrow grooves 11 and 12 and the angle of the peak part of a peak can be made the same as the above.

Next, the effect | action by a narrow groove is demonstrated, referring FIG. FIG. 8 is a diagram schematically showing the jet collision distribution of the gas wiping nozzle 1 of the first embodiment (see FIG. 3) when compared with a conventional gas wiping nozzle.
When the nozzle header pressure is constant, the conventional gas wiping nozzle has a broad jet collision distribution 61 as shown by a broken line. On the other hand, in the nozzle 1 of the present invention in which the narrow grooves 10 are provided on the inclined outer surfaces A and A ′, the jet collision distribution 60 is sharp as shown by the solid line. The reason for this is as follows.

  As the wiping gas 50 is blown out, accompanying flows 51 and 51 ′ are generated along the inclined outer surfaces A and A ′ of the gas wiping nozzle 1. The accompanying flows 51 and 51 ′ are directed in the same direction as the wiping gas 50. However, in the case of the conventional gas wiping nozzle, the accompanying flow 51, 51 ′ easily forms a turbulent vortex as indicated by reference numerals 52, 52 ′ around the nozzle tip, and the turbulent vortex 52, 52 When 'is generated, the smooth flow of the wiping gas 50 is disturbed, causing a splash problem, and the jet collision distribution 61 becomes wide, resulting in insufficient wiping capability.

  In the present embodiment, by forming the narrow grooves on the inclined outer surfaces A and A ′ of the gas wiping nozzle 1, it becomes possible to smoothly advance the accompanying flows 51 and 51 ′ in the wiping gas blowing direction. The generation of turbulent vortices 52 and 52 'can be effectively suppressed. As a result, the splash is reduced, and the wiping gas 50 has a sharp distribution like the jet collision distribution 60, and the wiping performance can be improved.

As mentioned above, although this invention was demonstrated based on typical embodiment, this invention is not restrict | limited to the said embodiment, A various deformation | transformation is possible.
For example, in the gas wiping nozzle 1 of the first embodiment described above, narrow grooves are formed on the inclined outer surfaces A and A ′, which are portions in contact with the accompanying flows 51 and 51 ′. It is also possible to form a narrow groove in a portion that contacts the blown gas flow. Specifically, in the upper lip 2 and the lower lip 3 in FIG. 3, the inclined inner surfaces B and B ′ formed so as to form an acute angle with respect to the wiping gas blowing direction, and parallel to the wiping gas blowing direction. A narrow groove can be formed on the parallel inner surfaces D and D ′ formed as described above. The inclined inner surfaces B and B ′ and the parallel inner surfaces D and D ′ are portions facing the wiping gas circulation part 5 connected to the nozzle port 4. In addition, narrow grooves can be formed on the opposing surfaces C and C ′ of the upper lip 2 and the lower lip 3 that form the nozzle opening 4.

  In particular, by providing narrow grooves in the portions indicated by reference characters B and B ′ and reference characters C and C ′, it becomes possible to smooth the gas flow that is blown out, and the jet collision distribution becomes sharper and the wiping performance is improved. It becomes possible to make it.

  Further, in the upper lip 2 and the lower lip 3 of FIG. 3, it is also possible to form narrow grooves on parallel outer surfaces E and E ′ formed so as to be parallel to the wiping gas blowing direction.

  Further, it is possible to provide narrow grooves on all surfaces A, A ′, B, B ′, C, C ′, D, D ′ and E, E ′ in FIG. It may be provided only on the surface. Furthermore, the narrow groove is not necessarily provided on the entire surface in each of the above surfaces, and can be provided partially. The fine groove may be formed by processing the nozzle surface, or may be formed by sticking a sheet or the like having a fine groove on the nozzle surface.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used in a hot dipping process for plating a surface of a metal band such as a steel band.

Drawing which shows the outline | summary of the hot dip metal strip manufacturing apparatus. Drawing which shows the detail of the broken-line part X in FIG. Drawing which shows schematic structure of the gas wiping nozzle of 1st Embodiment of this invention. The drawing for explaining a specific embodiment of the narrow groove. Drawing which shows the principal part cross section of a narrow groove. Drawing used for description of another embodiment of a narrow groove. The figure which uses for description of another embodiment of a narrow groove. The figure which shows typically the jet collision distribution of a gas wiping nozzle.

Explanation of symbols

1: Gas wiping nozzle 2: Upper lip 3: Lower lip 4: Nozzle port 5: Wiping gas circulation part 10, 11, 12: Narrow groove 50: Wiping gas 51, 51 ': Accompanying flow 52, 52': Turbulent vortex 60, 61: Jet collision distribution A, A ': Inclined outer surface B, B': Inclined inner surface C, C ': Opposing surface D, D': Parallel inner surface E, E ': Parallel outer surface

Claims (11)

In the gas wiping nozzle that blows off the excess molten metal adhering to the metal band by blowing gas when manufacturing the hot-dip metal band,
While forming a slit-like nozzle port with the width direction of the metal strip as the longitudinal direction,
A gas wiping nozzle comprising a groove in part or all of the outer surface of a nozzle body.   2. The gas wiping nozzle according to claim 1, wherein the groove is formed on an inclined surface and / or a parallel surface that forms an acute angle with the gas blowing direction toward the nozzle port. In the gas wiping nozzle that blows away the excess molten metal adhering to the metal band by blowing gas when manufacturing the hot-dipped metal band,
While forming a slit-like nozzle port with the width direction of the metal strip as the longitudinal direction,
A gas wiping nozzle characterized by having a groove in part or all of the inner surface of the nozzle body.   4. The gas wiping nozzle according to claim 3, wherein the groove is formed on an inclined surface and / or a parallel surface parallel to the gas blowing direction toward the nozzle port. 5. In the gas wiping nozzle that blows off the excess molten metal adhering to the metal band by blowing gas when manufacturing the hot-dip metal band,
While forming a slit-like nozzle port with the width direction of the metal strip as the longitudinal direction,
A gas wiping nozzle comprising a groove in part or all of the outer surface of the nozzle body and part or all of the inner surface of the nozzle body.   The groove portion is formed on an outer surface and an inner surface of the nozzle body on an inclined surface and / or a parallel surface that forms an acute angle with the gas blowing direction toward the nozzle port. The gas wiping nozzle described.   The gas wiping nozzle according to any one of claims 1 to 6, wherein the narrow groove constituting the groove portion is formed in parallel to a gas blowing direction.   The narrow groove constituting the groove is formed in a meandering manner, and an angle formed between a tangential direction of the groove and a gas blowing direction is 45 degrees or less. The gas wiping nozzle according to item 1.   The gas wiping nozzle according to any one of claims 1 to 8, wherein an angle of a crest portion of the narrow groove constituting the groove portion is 90 degrees or less.   The gas wiping nozzle according to any one of claims 1 to 9, wherein a height of a crest of the narrow groove constituting the groove portion is 1 mm or less.   An apparatus for producing a hot-dipped metal strip, comprising the gas wiping nozzle according to any one of claims 1 to 10.

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