Classifications

• • 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
• • 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
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/08—Rearranging applied substances, e.g. metering, smoothing; Removing excess material
  • D21H25/16—Rearranging applied substances, e.g. metering, smoothing; Removing excess material with a blast of vapour or gas, e.g. air knife

Definitions

• This invention relates to the control of thickness of a coating applied to the
• the present invention has been particularly developed for controlling the
• the hot dip galvanising process aims to apply a controlled amount of a protective
• galvanising line is employed to coat the sheet.
• the galvanising line 1 includes input coils 2 which carry a
• the metal sheet 3 is fed into an accumulator 4 and then passed
• X-ray gauges 47 are located down the line beyond the air knives 15 to monitor the
• the coat thickness is above the minimum required for the product in question.
• the coating thickness is controlled by the application of a high pressure wiping
• a typical air knife 15 is depicted schematically in
• the distance from the air knife mouth to the sheet surface is controlled by
• a bowed sheet profile can occur as the sheet exits the molten zinc bath
• proximal sheet surface 32 This has the effect of introducing a variation in the thickness
• Fig 3b illustrates a typical coating profile on the upper or
• Fig. 3c illustrates a typical coating profile on the lower or
• the width of the mouth opening varies at different points along its length. Constricting the width of the mouth reduces the gas flow at that point thus reducing the wiping effect
• US-4524716 discloses an air knife in which movable obstructions are provided
• gases gases, or even liquids, may be used and are encompassed by the invention.
• an air knife assembly including:
• moving means operable to move the lips relative to the air knife body.
• the present invention also provides an air knife mouth arrangement for use in an
• pressurised fluid passes to operate on a coating applied to a surface of a sheet material
• the air knife mouth arrangement including a pair of facing lips defining the
• the facing lips adapted to be movable relative to the air knife body.
• the lips is varied along at least part of the length of the mouth
• the present invention also preferably provides an air knife mouth arrangement
• pressurised fluid passes to operate on a coating applied to a surface of a sheet material
• the air knife mouth arrangement including a mouth defined by a pair of facing
• said facing lips configured and adapted to co-operate with each other such that upon
• mouth of the air knife can be employed to break free, and hence remove, small lumps of
• each lip of the pair of facing lips has, in front elevation, a curved
• each lip is provided along substantially the entire
• each lip is defined by a mathematical function which,
• each lip, in front elevation is defined by an odd
• each lip has an identical shape to the other lip, although for some reasons
• an initial non-uniform mouth width along its length may be required.
• the moving means of the air knife assembly is operable to move both
• the moving means is operative in response to signals from control
• control means including sensing means located past the air knife and
• this form of the present invention can be utilised to control the
• Fig. 1 is a diagrammatic view of a typical hot dip galvanising line for coating
• Fig. 2 is a schematic perspective view of a conventional air knife
• Fig. 3a is a horizontal sectional view of a pair of air knives operating on a bowed
• Figs. 3b & 3c illustrate a typical profile of the coating thickness resulting from
• Fig. 4 is a schematic perspective view of one preferred embodiment of an air
• Fig. 5 graphically depicts the mouth shape and mouth width variation of a
• Fig. 6 graphically depicts the mouth shape and mouth width variation of a
• Fig. 7 graphically depicts the mouth shape and mouth width variation of a
• FIG. 8a to 8c schematically depict plan views of a further preferred embodiment
• Fig. 9 schematically depicts a further preferred embodiment of air knife
• the present invention relates to an air knife mouth
• arrangement 20 comprises a mouth 16 defined by a pair of facing lips 17, 18, each lip
• lips 17, 18 face each other.
• the lips 17, 18 of the air knife mouth arrangement are
• the present invention also provides an air knife assembly 15, the assembly
• Means 12 are provided for distributing a fluid under pressure through the
• the moving means passing the air knife to thereby control the thickness of the coating.
• each lip 17, 18 is
• the mathematical function defining the shape or profile of the lips 17, 18 may be
• x lateral (transverse) coordinate, with origin as shown in Fig. 4
• A,B,C,D tuning constants chosen appropriately to achieve desired gap
• each air knife by lateral or sideways displacement of the respective facing lips.
• Fig. 4 and Fig. 6 will narrow the width of the mouth midway along the length of the
• the amplitude of the variation in width of the mouth will vary dependent on the
• the moving means 41 for displacing the lips laterally can be any suitable means.
• a mechanical arrangement such as gears may be used.
• a mechanical arrangement such as gears may be used.
• a mechanical arrangement such as gears may be used.
• a mechanical arrangement such as gears may be used.
• a mechanical arrangement such as gears may be used.
• a mechanical arrangement such as gears
• Fig. 4 is operative to simultaneously move both lips in opposite lateral directions.
• the moving means comprises racks 42, 43 connected to the
• the moving means 41 may be
• control means 46 including
• sensing means 47 located past the air knife and operative to sense the coating thickness
• air knife assembly enable the selective control of the width of the mouth at different
• the mouth arrangement can be relatively simple in construction
• mouth arrangement may be capable of being retro fitted to existing air knives so that the
• invention provides for the adjustment of the mean distance between the mouth of the air
• the air knife 15 is schematically depicted in plan view.
• FIG 8a depicts the air knife 15 with the lips of the air knife mouth 20 in a
• the moving means 86 can by utilised to move one end of the mouth forward and the
• a wedge member 92 may be located to act upon either or both of the lip
• the air knife supporting structure can be used to position the air

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Coating Apparatus (AREA)
• Coating With Molten Metal (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (6)

Cited By (1)

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Citations (8)

Family Cites Families (9)

• 1997
  • 1997-01-22 AU AUPO4732A patent/AUPO473297A0/en not_active Abandoned
• 1998
  • 1998-01-22 JP JP53142198A patent/JP4020217B2/ja not_active Expired - Fee Related
  • 1998-01-22 US US09/341,818 patent/US6199301B1/en not_active Expired - Lifetime
  • 1998-01-22 GB GB9916682A patent/GB2336377B/en not_active Expired - Fee Related
  • 1998-01-22 WO PCT/AU1998/000030 patent/WO1998032890A1/en not_active Ceased
  • 1998-01-22 DE DE19881989T patent/DE19881989B4/de not_active Expired - Fee Related

Patent Citations (8)

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