EP2140944A1 - Anpassbare Prallplatten für Gasabstreifer - Google Patents

Anpassbare Prallplatten für Gasabstreifer Download PDF

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Publication number
EP2140944A1
EP2140944A1 EP08012051A EP08012051A EP2140944A1 EP 2140944 A1 EP2140944 A1 EP 2140944A1 EP 08012051 A EP08012051 A EP 08012051A EP 08012051 A EP08012051 A EP 08012051A EP 2140944 A1 EP2140944 A1 EP 2140944A1
Authority
EP
European Patent Office
Prior art keywords
gas
metal product
metal
coating
gas outlet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08012051A
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English (en)
French (fr)
Inventor
Akin Malas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Linde GmbH
Original Assignee
Linde GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Linde GmbH filed Critical Linde GmbH
Priority to EP08012051A priority Critical patent/EP2140944A1/de
Publication of EP2140944A1 publication Critical patent/EP2140944A1/de
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/02—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface
    • B05C11/06—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface with a blast of gas or vapour
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/14—Removing excess of molten coatings; Controlling or regulating the coating thickness
    • C23C2/16—Removing excess of molten coatings; Controlling or regulating the coating thickness using fluids under pressure, e.g. air knives
    • C23C2/18—Removing excess of molten coatings from elongated material
    • C23C2/20—Strips; Plates

Definitions

  • the invention relates to a method for coating a metal product wherein a molten coating is applied to a surface of said metal product and wherein said metal product is passed through a control section where a sheet-like gas flow is directed to said metal product in order to wipe part of said molten coating off said metal product. Further, the invention relates to a gas wiping apparatus for wiping off a molten coating from a metal product comprising at least one gas outlet for providing a sheet-like gas jet.
  • Continuous hot-dip galvanizing of metal sheets is a well-known technique. This method involves the application of a molten coating onto the surface of a metal sheet in a continuous process.
  • the metal sheet is passed through a bath of a molten metal.
  • the surface of the metal sheet reacts with the molten metal to bond the coating onto the sheet surface.
  • excess liquid metal is bond to the surface, too.
  • the coating thickness is controlled.
  • This thickness control is achieved by a gas wiping process.
  • Gas nozzles deliver low-pressure, high-volume air streams on the surface of the metal sheet to wipe off surplus molten metal pulled from the molten metal bath. Since the gas nozzles "cut off” excess coating material they are often referred to as "gas knives".
  • gas knife shall mean a device for delivering a gas onto or along a surface, in order to wipe off surplus coating material.
  • air knife and “nitrogen knife” accordingly refer to devices for delivering air or nitrogen for gas wiping purposes.
  • Some of the steel manufacturers use nitrogen instead of air as the wiping gas in the steel galvanizing process.
  • the use of nitrogen has the advantage that a coating with improved surface quality is achieved due to the inertness of nitrogen.
  • the gas nozzles or gas knives are at least as long as the maximum width of the product to be processed. When a product of lesser width is processed the gas knives extend beyond the edges of the product.
  • width of the product shall mean the dimension of the metal product in a direction perpendicular to its transport direction and parallel to the surface which has been coated.
  • width of the sheet-like gas flow shall mean the dimension of the gas flow in a direction perpendicular to the transport direction of the metal product and parallel to the surface which has been coated.
  • width relates to the dimension of an object in a direction perpendicular to the transport direction of the metal product and parallel to the surface which has been coated.
  • PCT application WO 00/01861 A1 proposes baffles adjacent the edges of the processed strip and disposed between that part of the gas nozzles which extend beyond the strip edges, that is between the counter-flowing gas streams beyond the strip edges.
  • the baffles are provided with gas collection means for redirecting gas in order to avoid turbulence and hence to protect the strip edges.
  • baffles do not influence the gas output from the knives.
  • the gas flow rate is not changed and at least part of the gas flowing beyond the strip edges is wasted. This may not be an issue for air knives but for knives using nitrogen as wiping medium.
  • This object is achieved by a method for coating a metal product wherein a molten coating is applied to a surface of said metal product and wherein said metal product is passed through a control section where a sheet-like gas flow is directed to said metal product in order to wipe part of said molten coating off said metal product, and which is characterized in that the dimension of said sheet-like gas flow in a direction perpendicular to the transport direction of said passing metal product is adjusted depending on the dimension of said metal product in said direction perpendicular to the transport direction of said passing metal product.
  • the inventive gas wiping apparatus for wiping off a molten coating from a metal product comprises at least one gas outlet for providing a sheet-like gas jet, and is characterized in that means for reducing the opening cross section of said gas outlet are provided.
  • the width of the sheet-like gas flow which is used for wiping purposes is set depending on the width of the product to be processed.
  • the gas knife is preferably provided with at least one elongated gas outlet extending over a major part of the width of the gas knife.
  • one elongated gas outlet it is also possible to provide the gas knife with a number of smaller gas outlets which are arranged in line. Further it is possible to have two or more rows of gas outlets, either elongated gas outlets or a number of smaller gas outlets or a combination of both.
  • the opening cross section for example by closing part of the elongated gas outlet or by closing some of the gas outlets, the total gas flow out of the gas knife is reduced. Thereby, the gas consumption can be reduced by 30% to 60% compared to the existing prior art systems when narrower metal strips are produced.
  • the invention is preferably aimed at coating elongated metal products, in particular metal strips, metal sheets or metal wires, for example steel sheets or steel strips, which are continuously passed through a coating section where a molten coating is applied to a surface of the metal product.
  • the metal strip or metal sheet or in general the elongated metal product is transported through a coating bath where coating material from the coating bath is bond to the surface of the metal product.
  • coating material from the coating bath is bond to the surface of the metal product.
  • the elongated metal product exits the bath it drags out more coating material than needed for the coating.
  • the excess coating material is then wiped off the surface by the inventive wiping process.
  • a metal coating is applied to said metal product.
  • the coating which is applied to the metal product comprises one or more metals or composites of the group of zinc, aluminium, silicon.
  • the invention is directed to galvanizing a metal product, and even more preferred to galvanizing metal sheets or metal strips, in particular steel sheets or steel strips.
  • inventive method can also be used for the application of other coating materials to a metal product by hot-dip coating, that is by dipping the metal product into a bath of coating material.
  • the amount of excess coating material which is dragged out of the coating bath depends on the speed the metal product exits the bath. The higher the speed, the more coating material is dragged out of the bath.
  • the inventive method works well at speeds of the metal product between 1 m/min and 300 m/min that is it fits quite well into the speed range of standard hot-dip coating systems.
  • gas knife which blows a gas flow onto or along the surface of the passing metal product.
  • two gas knives are disposed on either side of the passing metal product with the gas outlets of each gas knife directed to respective sides of the passing surface.
  • the gas outlets for example elongated gas outlets or lines of small gas outlets, preferably extend in a direction parallel to the surface of the passing metal product and perpendicular to the transport direction of the metal product.
  • air and/or nitrogen as the wiping gas.
  • the air and / or nitrogen flow can further be pre-heated and then directed to the metal product for wiping off excess molten coating. It is especially preferred to use nitrogen as wiping gas.
  • nitrogen instead of air are reduced dross formation and improved surface quality.
  • an air flow and a nitrogen flow are directed to the metal product one after the other.
  • the invention can be used with air knives as well as with nitrogen knives or gas knives which are supplied with any other gas, fluid or steam.
  • the invention is in particular advantageous when gas wiping systems are used which are provided with two or more gas knives arranged in series. With such systems the gas consumption can be substantially reduced.
  • a gas wiping apparatus with an elongated gas outlet is preferably provided with means for reducing the width of the elongated gas outlet. By reducing the width of the gas outlet the width of the sheet-like gas stream leaving the gas outlet can be adjusted to the width of the passing metal product.
  • the gas wiping apparatus is provided with at least one baffle which is slidably arranged in the longitudinal direction of the elongated gas outlet such that at least a part of the gas outlet can be closed by the baffle.
  • the adjustment of the baffles or of any other means for reducing the opening cross section of the gas outlet is preferably carried out automatically. For that reason the baffles are connected to a motorized control system which adjusts the position of the baffles in terms of the width requirements.
  • the automatic control allows optimisation of the position of the baffles with respect to the gas consumption and the quality requirements.
  • means for example an optical sensor, for detecting the width of the metal product to be coated.
  • the motor is activated to move the baffles to the optimum position such that on the one hand excess liquid coating is sufficiently wiped off the metal product to achieve the desired product quality, and on the other hand the gas consumption is reduced as far as possible.
  • FIG. 1 schematically shows the inventive gas knife for wiping off excess molten zinc from a steel sheet.
  • a steel strip is transported at a high speed of for example about 150 m/min through a coating or galvanizing bath where a molten metal or metal alloy, for example zinc, is bond to the steel surface.
  • a molten metal or metal alloy for example zinc
  • the steel strip is covered with an over thick layer of molten zinc.
  • the steel strip exits the coating bath in a vertical direction.
  • Two gas knives are disposed on either side of the passing steel strip. In the figure only one gas knife 1 is shown. The second gas knife is identically to gas knife 1 but arranged mirror-inverted with the passing steel strip being the mirror plane.
  • Gas knife 1 comprises a chamber 2 with an elongated gas outlet 3.
  • Chamber 2 is connected to a supply of pressurised gas such as air or nitrogen.
  • Chamber 2 with the elongated gas outlet 3 extends transversely to the steel strip at a right angle to the direction of steel strip transport, that is the elongated gas outlet 3 is oriented in an essentially horizontal direction.
  • each gas knife 1 directs a sheet-like gas jet against the respective side of the passing steel strip. Thereby, any excess zinc which has been dragged off the coating bath is blown off the steel strip.
  • the width 4 of the elongated gas outlets 3 defines the maximum width of the steel strip to be processed by the gas knives 1.
  • the width 4 of the elongated gas outlets 3 is adjusted in terms of the width requirements.
  • Baffles 7, 8 are slidably arranged within the slits 5, 6.
  • the upper part of each baffle 7, 8 runs within the upper slit 5, the lower part of each baffle 7, 8 runs within the lower slit 6.
  • the position of the gas baffles 7, 8 defines the width of the sheet-like gas jet stream which exits gas knife 1 through the elongated gas outlet 3.
  • the baffles 7, 8 are connected to a computer controlled motor drive (not shown).
  • the computer controlled system allows to automatically set the position of the baffles 7, 8 when different steel strip gauges are produced.
  • the inventive system gives flexibility to set the gas streams such that on the one hand the gas consumption is reduced, and on the other hand the required surface quality of the edges of the steel strip is achieved.
  • Pressure and volume of the gas supplied to the gas knives 1 are also controlled depending on the speed of the steel strip, the desired thickness and quality of the coating, and/or the type of coating material. Further parameters which might be used to control pressure and volume of the gas and/or the position of the baffles 9, 10 are the height of the gas knife 1 above the coating bath, the distance of the gas knife 1 from the passing steel strip, the angle at which the gas jets impinge on the passing steel strip, or the dimensions of the elongated gas outlets 3.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Coating With Molten Metal (AREA)
EP08012051A 2008-07-03 2008-07-03 Anpassbare Prallplatten für Gasabstreifer Withdrawn EP2140944A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP08012051A EP2140944A1 (de) 2008-07-03 2008-07-03 Anpassbare Prallplatten für Gasabstreifer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP08012051A EP2140944A1 (de) 2008-07-03 2008-07-03 Anpassbare Prallplatten für Gasabstreifer

Publications (1)

Publication Number Publication Date
EP2140944A1 true EP2140944A1 (de) 2010-01-06

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP08012051A Withdrawn EP2140944A1 (de) 2008-07-03 2008-07-03 Anpassbare Prallplatten für Gasabstreifer

Country Status (1)

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EP (1) EP2140944A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015174234A1 (ja) * 2014-05-15 2015-11-19 Ｐｒｉｍｅｔａｌｓ Ｔｅｃｈｎｏｌｏｇｉｅｓ Ｊａｐａｎ株式会社 溶融金属めっき設備のワイピングノズル、及び、溶融金属めっき設備のワイピング位置制御装置

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3941086A (en) * 1973-08-08 1976-03-02 Italsider S.P.A. Fluid doctor blade
EP0249234A1 (de) * 1986-06-12 1987-12-16 DUMA Konstruktionsbüro Abblasvorrichtung zum kontinuierlichen beidseitigen Beschichten von Metallband
EP0278373A2 (de) * 1987-02-11 1988-08-17 Unitas S.A. Düse zum Abblasen kontinuierlich bewegter Oberflächen
DE4208558C1 (en) * 1992-03-18 1993-03-11 Duma Konstruktionsbuero, 4100 Duisburg, De Removing excess coating material from steel strip - with compressed air from nozzle having gap formed by nozzle lips partly coverable by guide strip and using deflecting element for lateral deflection of air jet
EP0566497A1 (de) * 1992-04-17 1993-10-20 Clecim Düsenmesser zur Steuerung der Beschichtungsdicke eines Metallüberzugs
US5683514A (en) * 1992-12-15 1997-11-04 Weirton Steel Corporation Coating control apparatus
WO1998032890A1 (en) * 1997-01-22 1998-07-30 Industrial Automation Services Pty. Ltd. Coating thickness control
WO2000001861A1 (en) 1998-06-30 2000-01-13 Bhp Steel (Jla) Pty. Ltd. Improvements in jet stripping apparatus
WO2003018859A2 (en) * 2001-08-24 2003-03-06 Posco Apparatus for controlling coating weight on strip in continuous galvanizing process

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3941086A (en) * 1973-08-08 1976-03-02 Italsider S.P.A. Fluid doctor blade
EP0249234A1 (de) * 1986-06-12 1987-12-16 DUMA Konstruktionsbüro Abblasvorrichtung zum kontinuierlichen beidseitigen Beschichten von Metallband
EP0278373A2 (de) * 1987-02-11 1988-08-17 Unitas S.A. Düse zum Abblasen kontinuierlich bewegter Oberflächen
DE4208558C1 (en) * 1992-03-18 1993-03-11 Duma Konstruktionsbuero, 4100 Duisburg, De Removing excess coating material from steel strip - with compressed air from nozzle having gap formed by nozzle lips partly coverable by guide strip and using deflecting element for lateral deflection of air jet
EP0566497A1 (de) * 1992-04-17 1993-10-20 Clecim Düsenmesser zur Steuerung der Beschichtungsdicke eines Metallüberzugs
US5683514A (en) * 1992-12-15 1997-11-04 Weirton Steel Corporation Coating control apparatus
WO1998032890A1 (en) * 1997-01-22 1998-07-30 Industrial Automation Services Pty. Ltd. Coating thickness control
WO2000001861A1 (en) 1998-06-30 2000-01-13 Bhp Steel (Jla) Pty. Ltd. Improvements in jet stripping apparatus
WO2003018859A2 (en) * 2001-08-24 2003-03-06 Posco Apparatus for controlling coating weight on strip in continuous galvanizing process

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015174234A1 (ja) * 2014-05-15 2015-11-19 Ｐｒｉｍｅｔａｌｓ Ｔｅｃｈｎｏｌｏｇｉｅｓ Ｊａｐａｎ株式会社 溶融金属めっき設備のワイピングノズル、及び、溶融金属めっき設備のワイピング位置制御装置
JP2015218345A (ja) * 2014-05-15 2015-12-07 Ｐｒｉｍｅｔａｌｓ Ｔｅｃｈｎｏｌｏｇｉｅｓ Ｊａｐａｎ株式会社 溶融金属めっき設備のワイピングノズル、及び、溶融金属めっき設備のワイピング位置制御装置
CN106232853A (zh) * 2014-05-15 2016-12-14 普锐特冶金技术日本有限公司 熔融金属镀敷设备的擦拭喷嘴及熔融金属镀敷设备的擦拭位置控制装置
US9951407B2 (en) 2014-05-15 2018-04-24 Primetals Technologies Japan, Ltd. Wiping nozzle of hot-dip metal plating equipment and wiping position control device for hot-dip metal plating equipment

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