US3742905A - Stripping excess coating liquid from moving strip material - Google Patents

Stripping excess coating liquid from moving strip material Download PDF

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Publication number
US3742905A
US3742905A US00168721A US3742905DA US3742905A US 3742905 A US3742905 A US 3742905A US 00168721 A US00168721 A US 00168721A US 3742905D A US3742905D A US 3742905DA US 3742905 A US3742905 A US 3742905A
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US
United States
Prior art keywords
strip
edge
baffle
baffle surface
stripping
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.)
Expired - Lifetime
Application number
US00168721A
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English (en)
Inventor
A Marks
H Cirson
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.)
John Lysaght Australia Pty Ltd
Original Assignee
John Lysaght Australia Pty Ltd
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 John Lysaght Australia Pty Ltd filed Critical John Lysaght Australia Pty Ltd
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Publication of US3742905A publication Critical patent/US3742905A/en
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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

Definitions

  • baffles are provided at each edge of the strip adjacent the stripping gas nozzles, the bat"- fles being urged towards the strip edges but restrained by followers in contact with the strip edges.
  • the coating liquid may be paint, glue, molten metal or other common coating liquid, and the strip (to which the particular coating must, of course, be appropriate) may be paper, metal or other strip material pliant enough for reeling and amenable to production in long runs; for example, lengths running to thousands of feet.
  • the present invention is applicable to jet stripping in the general sense indicated above, it is pri marily concerned with excess coating removal near the edges of steel strip during the stripping of excess molten coating metal as the strip emerges substantially vertically from a molten metal bath, and the invention is described hereinafter mainly in terms of that particular use.
  • one of the generally preferred methods of the prior art to remove excess coating metal from the steel strip, is to arrange for the coated strip, as it leaves the molten metal coating bath, to move vertically through a zone containing the jet stripping means and, once the coating has solidified and the coated strip cooled, the coated strip is then reeled.
  • the jet stripping means comprises essentially a pair of linearly extending gas nozzles disposed substantially horizontally on either side of the strip, at a distance above the surface of the coating bath such that the coating on the strip is still molten upon arrival in the stripping zone.
  • the lateral span of the stripping jets is normally greater than the width of strip passing between them. There may be substantial variations in the shape and design of nozzles, the jet span and gas pressure employed. The stripped matter simply flows downwardly from the stripping zone back to the bath. Jet stripping apparatus of the kind indicated above is hereinafter referred to as being of the type described.
  • a common occurrence in the use of apparatus of the type described is that a thicker coating remains on or near the edges of the strip than on the remaining area of the strip.
  • the thicker coating may extend in from the edges by up to three inches but is normally confined to a marginal area within one-fourth inch from the edge. Behavior of the gas stream is complex.
  • the sideways component of the blast in the vicinity of the strip edges causes some molten metal to be blown sideways as well as downwards, and this sideways fraction leaves the strip roughly horizontally in the form of fine spray.
  • This spray deposits on the jet nozzles and adjacent surfaces and can cause blockage of the slots from which the stripping jets emerge.
  • Molten metal forced to the edge of the strip and not completely removed solidifies and is retained causing rough and serrated edges; moreover, these rough edges and the more thickly coated margins of the strip militate against even and compact reeling of the cold coated strip.
  • the blast directed at a downwards and outwards angle of say 30 to to the strip path, blows large splashes of molten metal off the strip which fall harmlessly onto the bath. These splashes however, can solidify and accumulate on the surface of the bath making necessary their removal by remelting or other means.
  • An object of the present invention is to ameliorate the disabilities referred to above by counter-acting sideways motion of the stripping blast in the vicinity of the strip edge margins and the stripping zone, so that a uniform vertical downwards pressure gradient is maintained across the full width of the strip (including the strip edge margins) thereby removing excess coating liquid in the marginal areas, or reducing thatexcess to an amount which is inconsequential.
  • a further object of the invention is to provide means counteracting this sideways component of the stripping blast which is capable of adapting itself to lateral movement of the sheet in its own plane during its feed past the jets, and flapping of the strip as it passes the jets.
  • the invention resides in one broad aspect in apparatus for stripping excess coating liquid from an upwardly moving strip comprising means for directing a lateral gas stream normally onto a coated surface of the strip characterized in that it includes an edge baffle comprising a baffle surface disposed substantially at right angles to the plane of the strip and extending longitudinally of the strip closely adjacent and parallel to one edge thereof at the region of impingement of the. gas stream, the baffle surface being mounted so as to permit movement thereof towards and away from said edge, means urging the baffle surface towards said edge, and means maintaining a minimum spacing between said surface and said edge.
  • baffle surface is provided on each side of the strip.
  • baffle 2 functioning to modify the flow of the stripping jets at the edges of the strip. Only one of the two baffles and its associated assembly is shown, since they are identical with each other.
  • the baffle plate 2 consists of an elongated strip of sheet steel or other plate material and has a straight vertical portion 2a extending beside the strip 1. This vertical portion is of course located at the region of impingement of the stripping jets on the moving strip.
  • the baffle plate 2 is of such width as to more than span the greatest amount by which the strip may transversely depart from the mean strip path due to flapping movement of the strip or lack of flatness therein.
  • the height of the vertical section of the plate 2 is such that it overlaps the area of impingement of the jet to a sufficient extent that it covers the height of the strip over which the jet is able to influence sideways departure of coating liquid from the strip.
  • the baffle plate 2 is mounted, by welding along its center, on a vertical supporting plate 3 bolted to a bracket 4 by means of rectangularly crossing elongated slots 5 and 6. These elongated slots enable the position of the baffle plate relative to the moving strip 1 to be readily adjusted both in the vertical and horizontal direction.
  • the bracket 4 is supported by a truck 7 provided with rollers 8 which are able to move freely along a pair of horizontal tracks 9 spanning the path of the moving strip 1.
  • baffle plate extension is shaped in an arc to correspond with the downward and sidewards components of the jet blast beyond the edge of the moving strip so as to avoid (as far as possible) accumulation of metal splashes on the face of the baffle plate.
  • the flow of gas in the region of this curved surface creates a pressure differential between the front or strip side of the baffle plate and the back thereof, resulting in a thrust which urges the baffle plate towards the strip edge. It is found in practice that this baffle loading effect is quite substantial, and that the baffle will return inwards towards the strip if drawn or knocked outwardly, for example, due to sideways motion of the moving strip.
  • the baffle plate in operation, will be continually urged towards the edge of the strip so that a predetermined minimum distance is maintained between these two elements as the roller 10 follows the edge of the strip 1.
  • the curved extension 2b of the baffle plate has the additional advantage that it enables the baffle to be temporarily forced outwardly of the strip when struck by protruding portions of the strip, such as occur, for example, at joins between successive coils of strip.
  • the baffle While the outward curvature of the portion 2b minimizes the buildup of deposits by splashing of coating metal, this may be further reduced by making the baffle from a metal having a high thermal conductivity, such as brass.
  • the baffle being constantly chilled by an air blast, enables the splashes to solidify rapidly and fall harmlessly down into the molten metal bath.
  • the baffle surface be approximately normal to the adjacent edge of the strip and extend a short distance above and below the stripping zone in order to maintain a pocket of stagnation pressure in this region.
  • This pressure is established by an adjustment of the distance of the bafi'le surface from the edge of the strip depending on the circumstances of jet pressure, angle of tilt and other factors which determine the force of the dead wood component of the jets.
  • the width of the baffle surface should be at least sufficient to maintain a pocket of stagnation pressure adjacent to the edge of the strip despite variations in the distance between the strip and the jet nozzles caused by lack of flatness of the strip or flapping.
  • the mounting means provided for the baffle plate may take many forms.
  • the plate may be fixed on the free end of a swingable arm pivoted by its other arm at a considerable distance from the stripping zone; a distance such that during any normal working movement of the plate towards or away from the strip edge, the baffle surface of the plate remains, for all practical purposes, substantially parallel to that edge.
  • the plate may be mounted on one arm of a parallelogram linkage, in which case the plate will rise or fall a little, relative'to the stripping zone, when it moves translationally, but will remain parallel with the strip edge.
  • the loading means for the baffle plate may consist of a light loading spring attached to the truck 7 or of making the rails 9 slightly tilted so that the truck tends to run downhill towards the adjacent edge of the moving strip.
  • the following means which maintain the baffle surface at its minimum spacing relative to the adjacent strip edge may consist of a skid which rides that edge or some other suitable device.
  • Apparatus for stripping excess coating liquid from an upwardly moving strip comprising means for directing a lateral gas stream normally onto a coated surface of the strip wherein the improvement comprises an edge baffle comprising a baffle surface disposed substantially at right angles to the plane of the strip and extending longitudinally of the strip closely adjacent and parallel to one edge thereof and over the longitudinal extent of the region of impingement of the gas stream, the baffle surface being mounted so as to permit movement thereof towards and away from said edge, means urging the baffle surface towards said edge, and means maintaining a minimum spacing between said surface and said edge.
  • Apparatus as claimed in claim 1 further characterized in that said means urging the baffle surface towards said edge is thrust generated on a longitudinal extension of the baffle surface by the passage past said extension of gas from said stream after deflection by the coated surface.
  • baffle surface is of a width greater than the extent of transverse departures from the mean path thereof occurring adjacent the baffle surface.
  • Apparatus as claimed in claim 1 wherein said means maintaining a a minimum spacing comprises follower means adapted to engage said edge to prevent the baffle approaching said edge beyond said minimum spacing.
  • the baffle surface comprises a metal having a high thermal conductivity.

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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)
  • Coating Apparatus (AREA)
US00168721A 1970-08-13 1971-08-03 Stripping excess coating liquid from moving strip material Expired - Lifetime US3742905A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AUPA218970 1970-08-13

Publications (1)

Publication Number Publication Date
US3742905A true US3742905A (en) 1973-07-03

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ID=3764686

Family Applications (1)

Application Number Title Priority Date Filing Date
US00168721A Expired - Lifetime US3742905A (en) 1970-08-13 1971-08-03 Stripping excess coating liquid from moving strip material

Country Status (9)

Country Link
US (1) US3742905A (xx)
JP (1) JPS517178B1 (xx)
BE (1) BE771182A (xx)
CA (1) CA943334A (xx)
DE (1) DE2140383C3 (xx)
FR (1) FR2105913A5 (xx)
GB (1) GB1325235A (xx)
MY (1) MY7400157A (xx)
ZA (1) ZA715362B (xx)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1984003458A1 (en) * 1983-03-11 1984-09-13 Enacon Ltd Curing of surface coatings
US20030161955A1 (en) * 2002-02-26 2003-08-28 Eastman Kodak Company Method and system for coating
US20090233537A1 (en) * 2008-03-14 2009-09-17 Inventec Corporation Air baffle and calculation method of deformational stress thereof
US20110186141A1 (en) * 2008-05-15 2011-08-04 Siemens Vai Metals Technologies Sas Device and method for positioning two baffles associated with wiping of a galvanizing product

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NZ179743A (en) * 1975-01-13 1979-01-11 Nat Steel Corp Coating sheet material reducing edge affect impinging jets
AU543722B2 (en) * 1981-01-21 1985-05-02 John Lysaght (Australia) Limited Removing excess liquid coating from moving strip

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2390007A (en) * 1943-12-31 1945-11-27 Dominion Foundries & Steel Apparatus for continuously hot dip coating of tin on coiled strip
DE912190C (de) * 1951-11-20 1954-05-28 Siemens Ag Lackabstreifer fuer Lackdrahtherstellung
US2888901A (en) * 1957-10-17 1959-06-02 Bethlehem Steel Corp Coating control apparatus
US2967114A (en) * 1958-07-22 1961-01-03 Nat Steel Corp Coating apparatus and method
US3032006A (en) * 1958-12-22 1962-05-01 Olin Mathieson Web treatment
US3140960A (en) * 1961-06-28 1964-07-14 Inland Steel Co Edge scraping apparatus
US3494324A (en) * 1968-03-04 1970-02-10 United States Steel Corp System for controlling the air supply to coating-screeding air knives
US3681119A (en) * 1970-05-26 1972-08-01 Lysaght Australia Ltd Stripping excess coating liquid from moving strip materials

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2390007A (en) * 1943-12-31 1945-11-27 Dominion Foundries & Steel Apparatus for continuously hot dip coating of tin on coiled strip
DE912190C (de) * 1951-11-20 1954-05-28 Siemens Ag Lackabstreifer fuer Lackdrahtherstellung
US2888901A (en) * 1957-10-17 1959-06-02 Bethlehem Steel Corp Coating control apparatus
US2967114A (en) * 1958-07-22 1961-01-03 Nat Steel Corp Coating apparatus and method
US3032006A (en) * 1958-12-22 1962-05-01 Olin Mathieson Web treatment
US3140960A (en) * 1961-06-28 1964-07-14 Inland Steel Co Edge scraping apparatus
US3494324A (en) * 1968-03-04 1970-02-10 United States Steel Corp System for controlling the air supply to coating-screeding air knives
US3681119A (en) * 1970-05-26 1972-08-01 Lysaght Australia Ltd Stripping excess coating liquid from moving strip materials

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1984003458A1 (en) * 1983-03-11 1984-09-13 Enacon Ltd Curing of surface coatings
US20030161955A1 (en) * 2002-02-26 2003-08-28 Eastman Kodak Company Method and system for coating
US20090233537A1 (en) * 2008-03-14 2009-09-17 Inventec Corporation Air baffle and calculation method of deformational stress thereof
US20110186141A1 (en) * 2008-05-15 2011-08-04 Siemens Vai Metals Technologies Sas Device and method for positioning two baffles associated with wiping of a galvanizing product

Also Published As

Publication number Publication date
GB1325235A (en) 1973-08-01
FR2105913A5 (xx) 1972-04-28
JPS517178B1 (xx) 1976-03-05
DE2140383B2 (de) 1978-04-20
DE2140383A1 (de) 1972-02-17
CA943334A (en) 1974-03-12
MY7400157A (en) 1974-12-31
BE771182A (fr) 1971-12-16
DE2140383C3 (de) 1978-12-14
ZA715362B (en) 1972-04-26

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