JP6052549B2 - Gas wiping nozzle - Google Patents

Description

      The present invention relates to a gas wiping nozzle that is used in a manufacturing process of a hot dipped metal strip and supplies a wiping gas to the metal strip to wipe off excess molten metal adhering to the metal strip.

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

      The hot dipping method will be described with reference to FIG. 4. First, the metal strip 101 such as a steel plate rolled in the cold rolling process and cleaned in the subsequent cleaning process is brought into a non-oxidizing or reducing atmosphere. After removing the surface oxide film in the maintained annealing furnace and annealing, it is cooled to about the same temperature as the molten metal solution 104, and then rolled in the molten metal solution 104 such as zinc in the plating tank 103. This is a method in which the molten metal liquid 104 is adhered to the surface by dipping by passing through the plate while being reversed at 105. The metal strip 101 pulled up from the plating tank 103 wipes off the excessive molten metal liquid 104 by blowing wiping gas ejected from the gas wiping nozzles 102 and 102 disposed so as to be sandwiched from both the front and back sides of the metal strip. The amount of metal attached is adjusted.

      However, this hot dipping method has many advantages, such as the ability to produce a plated metal strip at low cost and the ability to easily produce a thick plated metal strip, but in gas wiping, the tip of the nozzle is made of metal. Since the excess molten metal is wiped off by the discharge gas in a state of being very close to the belt, the wiped molten metal droplet 106 adheres to the tip of the nozzle. In some cases, there is a problem that the adhered molten metal droplet 106 locally closes the nozzle slit and causes nozzle clogging. When nozzle clogging occurs, the wiping force of the discharge gas is locally weakened. As a result, the amount of plating adhered to the metal band remains, and a defective product is manufactured. .

      Moreover, the adhesion of molten metal droplets is very strong and does not easily drop off due to the force of the discharge gas, so if a nozzle is clogged, insert a dedicated cleaning jig into the nozzle slit. It was being cleaned. However, in such a method, the product cannot be produced during the nozzle cleaning, which deteriorates the yield.

      Therefore, in order to prevent molten metal droplets from adhering to the nozzle tip, the wiping nozzle shape can be devised, or as a countermeasure when molten metal droplets adhere to the nozzle tip, hard chrome plating, etc. Surface treatment is performed.

      For example, there is a gas wiping nozzle described in Japanese Patent Application Laid-Open No. 2007-270161 as a devised wiping noise shape. In this gas wiping nozzle, the angle α formed with the horizontal surface on the nozzle front end side of the nozzle upper surface is in the range of 10 to 20 degrees, the length of the portion is 5 to 40 mm, and 45 to 45 mm on the nozzle rear end side. Flat within the range of 50 degrees, the angle β formed with the horizontal surface of the inclined surface of the lower surface of the nozzle is small on the nozzle tip side, and further, the angle γ formed with the slit surface at the nozzle front end is within the range of 80 to 110 degrees. And the curvature radius R of the lower corner portion of the nozzle upper member at the slit tip of the gas wiping nozzle and the curvature radius R of the upper corner portion of the nozzle lower member are both 0.5 mm or less. By adopting such a shape, it is described that the flow of the discharge gas from the wiping nozzle can be controlled and the scattering of molten metal splash can be reduced.

      Moreover, there is a gas wiping nozzle described in Japanese Utility Model Publication No. 63-34161 as a configuration in which the surface of the nozzle body is subjected to surface treatment such as hard chrome plating. In this gas wiping nozzle, there is described a configuration in which hard chrome plating is applied to the surface to which the molten metal splashes scattered at the time of gas wiping adhere on at least the surface facing the upper mold slit and the outer surface of the upper mold and the lower mold. It is described that even when molten metal droplets adhere, it is possible to remove the adhered molten metal droplets easily when cleaning with a dedicated cleaning jig.

JP 2007-270161 A Japanese Utility Model Publication No. 63-34161

      However, as disclosed in Patent Document 1, no matter how much the shape of the gas wiping nozzle is devised, it is not possible to prevent the splashing of the molten metal, and recently, the movement of a metal strip such as a steel plate for the purpose of increasing production. Since the gas pressure of the gas wiping nozzle is set higher as a result of increasing the speed, it is unavoidable that the molten metal splash increases, and the adhesion of the molten metal splash to the wiping nozzle can be prevented. Can not. Further, as a method for controlling the discharge gas, a configuration in which a sub nozzle is separately provided for control is also considered, but as a result, splashes cannot be eliminated.

      Also, as in Patent Document 2, on the assumption that molten metal splash cannot be eliminated, a hard chrome plating layer is provided on the surface of the nozzle, and the molten metal splash adheres to the nozzle and is cleaned by a dedicated cleaning jig. Even if the molten metal splash adhering to the surface can be easily removed, it is necessary to clean frequently, and even if it is cleaned, the hard chromium plating layer is damaged. Further, although WC spraying (tungsten carbide spraying) is used as a surface treatment, it is not so different from providing a hard chrome plating layer.

      That is, in general, the nozzle body of the gas wiping nozzle is made of SCM (chrome molybdenum steel) and the surface thereof is subjected to surface treatment. The thickness of the surface treatment layer is 30 to 30 in a hard chrome plating layer. 50 μm, 50 to 100 μm by WC spraying. As a result, the slit portion of the nozzle is easily damaged by the discharge of the wiping gas, and the repair is often required. Moreover, although it is necessary to carry out cleaning to remove the molten metal splashes that frequently adhere, it is often damaged by cleaning and often requires repairs. In the repair, all the surface-treated portions are peeled off and then the re-surface treatment is performed. Therefore, the productivity is remarkably deteriorated, and since the repair is frequently required, the running cost is not stupid. Also, in order to control the discharge gas, it is necessary to edge process the tip of the nozzle body. However, with hard chrome plating or WC spraying, if the edge is raised, blade spillage will occur and the edge cannot be raised. In this state, it is difficult to create a delicate tip edge shape that can adjust the discharge gas.

      The gas wiping nozzle of the present invention has been developed to solve the problem of molten metal splash that has been continued from the past and has not yet been fully solved.

      The gas wiping nozzle of the present invention is a gas wiping nozzle used in a manufacturing process of a hot-dip metal strip, and is a gas wiping which has a surface treatment on the tip of the gas wiping nozzle body as a countermeasure against wiping molten metal splashes At the tip of the gas wiping nozzle body where molten metal droplets adhere to the nozzle, an HIP layer is formed by direct diffusion bonding of alloy powder made of nickel-based alloy or cobalt-based alloy with good corrosion resistance and wear resistance by HIP treatment In addition, the surface of the HIP layer is mirror-polished.

      The gas wiping nozzle of the present invention is characterized in that the base material constituting the gas wiping nozzle body is made of austenite / ferrite duplex stainless steel.

      The gas wiping nozzle of the present invention is a gas wiping nozzle manufacturing method in which at least the tip of the gas wiping nozzle body to which molten metal droplets adhere is gasified with an alloy powder having good corrosion resistance and wear resistance by HIP treatment. The wiping nozzle body is formed by an HIP layer directly joined to a base material constituting the wiping nozzle body.

      In the gas wiping nozzle of the present invention, an alloy powder made of a nickel-based alloy or a cobalt-based alloy having good corrosion resistance and wear resistance is directly diffusion-bonded by HIP treatment at the tip of the gas wiping nozzle body to which molten metal droplets adhere. In addition, since the HIP layer is formed and the surface of the HIP layer is mirror-polished, it is difficult for molten metal splash to adhere, and adhesion of the molten metal splash scattered by the discharge gas to the nozzle tip can be suppressed. .

      Further, since the surface of the HIP layer is mirror-polished, the adhered molten metal splash can be easily removed without damaging the nozzle using a dedicated cleaning tool.

      Moreover, hard chrome plating or WC spraying as a surface treatment layer cannot ensure a sufficient thickness and frequent resurface treatment by repair is required, but the HIP layer has a thickness of 5 to 10 mm. As a result, rupture can be done several tens of times with only training processing, and the operation rate can be improved when production increases.

      Further, since the surface treatment is the HIP layer, it is possible to make an edge even in the edge treatment of the nozzle tip, and the discharge gas can be easily controlled.

      As a result, the running cost is less than half that of a gas wiping nozzle provided with a hard chrome plating layer or a WC sprayed layer.

Drawing of gas wiping nozzle provided with HIP layer of the present invention Drawing showing processing of the tip of the gas wiping nozzle of the present invention Drawing in which hot dip plating is performed using the gas wiping nozzle of the present invention Drawing explaining the hot dipping process

      Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the gas wiping nozzle 1 has a nozzle body 4 composed of an upper member 2 and a lower member 3, and a wiping gas flow path 6 is provided between the upper member 2 and the lower member 3. The tip 5 is a slit.

      The gas wiping nozzle 1 is characterized by corrosion resistance at least on the inclined surface 2a, the slit surface 2b of the upper member 2, the inclined surface 3a of the lower member 3, and the slit surface 3b, which are tip portions of the nozzle body 4 to which molten metal droplets adhere. In addition, the HIP layer 7 is formed by directly diffusing and bonding the alloy powder having good wear resistance to the base material of the nozzle body 4 by HIP (hot isostatic pressing). Each drawing is indicated by a hatched pattern. The HIP layer has a thickness of 5 to 10 mm, the length of the inclined surface 2a of the upper member 2 and the inclined surface 3a of the lower member 3 is at least 100 mm, and the slit surface 2b of the upper member 2 and the lower member 3 The length of the slit surface 3b is at least 20-30 mm.

      The material of the nozzle body 4 may be an SC (chromium steel) material or an SCM (chromium molybdenum steel) material generally used for gas wiping nozzles in consideration of the bonding property with the HIP layer. Moreover, SUS329J1-4 (austenite / ferrite two-phase stainless steel) having a thermal expansion coefficient close to that of the nickel-based alloy powder or cobalt-based alloy powder used for the alloy powder of the HIP layer 7 can also be employed.

      Nickel alloy powder or cobalt alloy powder is used as the alloy powder having good corrosion resistance and wear resistance used for the HIP layer. Preferred constituents of the nickel-based alloy powder are as follows: nickel 69.75% by weight, chromium 16.5% by weight, boron 3.3% by weight, silicon 4.0% by weight, carbon 0.65% by weight, iron 3. 5% by weight, molybdenum 3.0% by weight and copper 2.3% by weight. Other preferred nickel-based alloy powders are 58.2% nickel, 18.0% chromium, 3.3% boron, 3.7% silicon, 0.8% carbon, 1.5% iron. And 2.5% by weight molybdenum and 12.0% by weight tungsten. Still another preferred nickel-based alloy powder is nickel 50.05% by weight, chromium 19.0% by weight, boron 3.0% by weight, silicon 3.1% by weight, carbon 0.85% by weight, iron 1.5% by weight. %, Molybdenum 2.5% by weight and tungsten 20.0% by weight. On the other hand, the preferred cobalt-based alloy powder has a constituent element ratio of 45.7 wt% cobalt, 19.0 wt% chromium, 15.0 wt% tungsten, 1.3 wt% copper, 13.0 wt% nickel. %, Boron 3.0% by weight and silicon 3.0% by weight.

      The manufacturing method for forming the HIP layer on the nozzle body 4 is a well-known method, for example, a manufacturing method similar to the manufacturing method for the coating die comprising the die body provided with the HIP layer described in Japanese Patent No. 4882017. can do.

      When the nozzle body 4 is created, the surfaces of the HIP layers provided on the upper member 2 and the lower member 3 are mirror-finished by mirror grinding. The tip edge of the HIP layer is finished at 1 μm, and the surface roughness (surface roughness) is finished with an accuracy of Ry (maximum height) of 0.1 μm. If further lapping is performed, the surface roughness of the mating surfaces can be finished to Ry0.0 alpha units.

      FIG. 2 illustrates the processing of the tip of the nozzle body provided with the HIP layer. Since the HIP layer has a sufficient surface treatment thickness, the tip is rounded as shown in FIG. 2 (a) in consideration of the amount and direction of the discharge gas and the scattered state of the molten metal splash. It can be ground freely, including surface treatment and C-surface treatment with the tip cut as shown in FIG. It is also possible to create a delicate tip edge shape.

      FIG. 3 shows an HIP layer in which an alloy powder made of nickel-based alloy or cobalt-based alloy having good corrosion resistance and wear resistance is directly diffusion-bonded by HIP treatment at the tip of a gas wiping nozzle body to which molten metal droplets adhere. 7, and the gas wiping nozzle 1 in which the surface of the HIP layer 7 is mirror-polished is used. The metal strip 8 such as a steel plate pulled up from the plating tank (not shown) is excessively exposed by the wiping gas sprayed from the gas wiping nozzles 1 and 1 disposed so as to be sandwiched from both the front and back sides of the metal strip. The molten metal liquid is wiped off to adjust the amount of metal attached.

      At that time, molten metal droplets 9 are formed, and the molten metal droplets 9 scattered under the influence of the turbulent air flow due to the discharge gas are attached to the HIP layer 7 at the tip of the nozzle. However, the HIP layer of the nozzle main body 4 is processed into a delicate tip shape so that the discharge gas can be finely controlled, and is formed so as to minimize the scattering of the molten metal droplets 9. Moreover, since the front-end | tip part of the nozzle main body 4 is formed with the HIP layer 7 by which the mirror surface grinding process was carried out, possibility that it will adhere can be decreased as much as possible. Therefore, adhesion of molten metal droplets to the nozzle body 4 can be reduced, and the adhered molten metal droplets can be easily removed because the HIP layer is mirror-polished. Moreover, even if it is necessary to repair, it can be done several tens of times simply by grinding the HIP layer, so there is no need to peel off the surface treatment layer and form a resurface treatment layer, without reducing productivity. This makes it possible to increase the production of hot-dip metal strips with reduced maintenance costs.

DESCRIPTION OF SYMBOLS 1 Gas wiping nozzle 2 Upper member 2a Upper member inclined surface 2b Upper member slit side surface 3 Lower member 3a Lower member inclined surface 3b Lower member slit side surface 4 Nozzle body 5 Slit 6 Gas flow path 7 HIP layer 7a R surface 7b C surface 8 Steel plate 9 Molten metal splash 101 Metal strip 102 such as steel plate Gas wiping nozzle 103 Plating tank 104 Molten metal liquid 105 Roll 106 Molten metal splash

Claims (2)

      This is a gas wiping nozzle used in the manufacturing process of hot dip metal strip, and the molten metal splash adheres to the gas wiping nozzle that has surface treated the tip of the main body of the gas wiping nozzle as a countermeasure against the wiping molten metal splash. Forming an HIP layer formed by directly diffusion-bonding an alloy powder made of a nickel-based alloy or a cobalt-based alloy having good corrosion resistance and wear resistance by HIP treatment at the tip of the gas wiping nozzle body, A gas wiping nozzle characterized in that the surface is mirror-polished.       2. The gas wiping nozzle according to claim 1, wherein the base material constituting the gas wiping nozzle body is made of austenite / ferrite duplex stainless steel.

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