CA1082912A - Apparatus for liquid coating thickness control, fluid nozzle and method of removing excess liquid coating from web edges - Google Patents
Apparatus for liquid coating thickness control, fluid nozzle and method of removing excess liquid coating from web edgesInfo
- Publication number
- CA1082912A CA1082912A CA243,363A CA243363A CA1082912A CA 1082912 A CA1082912 A CA 1082912A CA 243363 A CA243363 A CA 243363A CA 1082912 A CA1082912 A CA 1082912A
- Authority
- CA
- Canada
- Prior art keywords
- fluid
- web
- forming means
- liquid coating
- nozzle
- 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
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/40—Distributing applied liquids or other fluent materials by members moving relatively to surface
- B05D1/42—Distributing applied liquids or other fluent materials by members moving relatively to surface by non-rotary members
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
- B05B1/02—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means designed to produce a jet, spray, or other discharge of particular shape or nature, e.g. in single drops, or having an outlet of particular shape
- B05B1/04—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means designed to produce a jet, spray, or other discharge of particular shape or nature, e.g. in single drops, or having an outlet of particular shape in flat form, e.g. fan-like, sheet-like
- B05B1/044—Slits, i.e. narrow openings defined by two straight and parallel lips; Elongated outlets for producing very wide discharges, e.g. fluid curtains
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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
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- 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
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)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
APPARATUS FOR LIQUID COATING THICKNESS
CONTROL, FLUID NOZZLE AND METHOD OF REMOVING
EXCESS LIQUID COATING FROM WEB EDGES
Abstract of the Disclosure A nozzle and associated apparatus for controlling the thickness of liquid coating on continuous webs which produces a thin jet of fluid for impingement across the width of moving web having a liquid coating thereon, the fluid in the portions of the jet on either side of the center of the nozzle having com-ponents of motion toward the edges of the web. One form of nozzle structure for achieving such lateral movement of the fluid issuing from the nozzle has a centrally positioned fluid inlet port to an inner plenum chamber, the port having a cross sectional area at least several times the cross sectional area of the nozzle orifice. Another form of nozzle structure for accomplishing this purpose involves baffle means in the path of the fluid flowing through the nozzle which changes the direction of flow of the fluid so as to give the fluid on either side of the center of the nozzle a component of motion toward the edges of the nozzle. Still another form of nozzle structure combines the foregoing features with the so-called curved orifice nozzle where operating conditions indicate the desirability of some build up of coating on the central portion of the web. The method involves impinging fluid against a liquid coating on a sur-face of a moving web with the fluid impinging against the liquid coating across the width of the web so that on either side of the center of the web there is a component of motion of the fluid toward each associated edge of the web, whereby excess liquid coating on the web has a component of motion toward each edge of the web.
CONTROL, FLUID NOZZLE AND METHOD OF REMOVING
EXCESS LIQUID COATING FROM WEB EDGES
Abstract of the Disclosure A nozzle and associated apparatus for controlling the thickness of liquid coating on continuous webs which produces a thin jet of fluid for impingement across the width of moving web having a liquid coating thereon, the fluid in the portions of the jet on either side of the center of the nozzle having com-ponents of motion toward the edges of the web. One form of nozzle structure for achieving such lateral movement of the fluid issuing from the nozzle has a centrally positioned fluid inlet port to an inner plenum chamber, the port having a cross sectional area at least several times the cross sectional area of the nozzle orifice. Another form of nozzle structure for accomplishing this purpose involves baffle means in the path of the fluid flowing through the nozzle which changes the direction of flow of the fluid so as to give the fluid on either side of the center of the nozzle a component of motion toward the edges of the nozzle. Still another form of nozzle structure combines the foregoing features with the so-called curved orifice nozzle where operating conditions indicate the desirability of some build up of coating on the central portion of the web. The method involves impinging fluid against a liquid coating on a sur-face of a moving web with the fluid impinging against the liquid coating across the width of the web so that on either side of the center of the web there is a component of motion of the fluid toward each associated edge of the web, whereby excess liquid coating on the web has a component of motion toward each edge of the web.
Description
---` 10~32512 B kground of the Invention In hot metal dip coating processes for metals such as zinc and aluminum and in the coated paper and film industries, the thicknes~
of the liquid coating remaining on the metal strip, film or paper web, all three being herein 60metimes generically referred to as webs, must be controllet to obtain a satisfactory product. One of the difficulties encountered in obtaining a web with unifonm liquid coating thickness is the occurrence of heavy edge coating, a phenomenon that has become known as edge effect. In this phenomenon, due to the complexities of fluid ]0 flow from the opposing nozzles at the edges of the web, the liquid coat-ing remaining on the web is heavier close to and along the edges or marginal portions of the web. Much effort has been expended in attempt-ing to eliminate this difficulty.
United States patents proposing solutions for eliminating edge effect are 3,406,656; 3,480,469; 3,526,204; 3,670,695; 3,672,324; 3,687,103 3,742,905 and 3,773,013.
In addition to the waste of coating material and other problems which result from edge effect in the coated paper and film environments, in the metal coating industry where the strip metal such as steel is 2U coated wlth coating metal such as zinc and aluminum a further very ~ erious difficulty arise~ from edge effect. The coated metal strip is ~';
coiled as it is produced for convenience in handling and shipping. The slightly thicker coating metal at the edges of the strip results in "spooling" in the usual large coil. In spooling the strip assumes a con-cave configuration as the coil builds up. Spooling is a very serious r, defect because it can cause the strip edge to be stretched plastically `i resulting in a wavy edge when the strip is uncoiled. Such strip is commercially unacceptable.
Several of the above cited U.S. patents attempt to explain the phenomens which resu~t in edge effect in strip or web coating. Regard-less as to what explanations are correct, applicant has discovered that
of the liquid coating remaining on the metal strip, film or paper web, all three being herein 60metimes generically referred to as webs, must be controllet to obtain a satisfactory product. One of the difficulties encountered in obtaining a web with unifonm liquid coating thickness is the occurrence of heavy edge coating, a phenomenon that has become known as edge effect. In this phenomenon, due to the complexities of fluid ]0 flow from the opposing nozzles at the edges of the web, the liquid coat-ing remaining on the web is heavier close to and along the edges or marginal portions of the web. Much effort has been expended in attempt-ing to eliminate this difficulty.
United States patents proposing solutions for eliminating edge effect are 3,406,656; 3,480,469; 3,526,204; 3,670,695; 3,672,324; 3,687,103 3,742,905 and 3,773,013.
In addition to the waste of coating material and other problems which result from edge effect in the coated paper and film environments, in the metal coating industry where the strip metal such as steel is 2U coated wlth coating metal such as zinc and aluminum a further very ~ erious difficulty arise~ from edge effect. The coated metal strip is ~';
coiled as it is produced for convenience in handling and shipping. The slightly thicker coating metal at the edges of the strip results in "spooling" in the usual large coil. In spooling the strip assumes a con-cave configuration as the coil builds up. Spooling is a very serious r, defect because it can cause the strip edge to be stretched plastically `i resulting in a wavy edge when the strip is uncoiled. Such strip is commercially unacceptable.
Several of the above cited U.S. patents attempt to explain the phenomens which resu~t in edge effect in strip or web coating. Regard-less as to what explanations are correct, applicant has discovered that
-2-`: A' by impinging against a moving web coated with liquid a stream of fluid which has a component of motion toward each edge of the strip or web, edge effect in the finally coated product can be greatly reduced or even entirely eliminated and for practical purposes substantially uniform coating thickness obtained across the width of the web.
Abstract of the Invention The present invention is the discovery that fluid from opposing nozzles impinging against a moving web to control the thickness of coat-ing liquid on the web will ameliorate or eliminate edge effect when the fluid has a component of motion toward each edge of the web sufficient to cause excess liquid coating in the vicinity of each edge of the web to have a component of motion toward each edge of the web (in sddition to the component of motion of excess liquid coating downwardly) to thereby obtain substantially uniform liquld coating thickness across the width of the web.
; Additionally applicant has discovered how to construct a fluid no~zle and arrange the same in a liquid coating thickness control appara-~,, tus so as to obtain the desired movement of fluid and coating liquid as ~' Ju~t described and thereby obtain substantially uniform liquid coating ,, 20 thickness across the width of a web.
"~, Accordingly, there is provided in accordance with the present ~:. invention the method of removing excess liquid coating from one surface of a traveling web comprising (a) supplying a source of fluid under .~ pressure, (b) forming a stream of the f]uid, (c) shaping the stream of . fluid so as to form a single, unitary stream which impinges against the one surface of the web across the width thereof to remove excess liquid coating from the one surface, (d) controlling the direction of fluid move-., ment in the stream of fluid impinging against the one surface of the web to cause movement of excess liquid coating on the traveling web outwardly !.~1' ~,~ 30 toward the longitudinal edges of the web.
There is also provided in accordance with the present invention ' '" ~
` A~ ~ 3 ~08~5~1Z
in combination with a palr of opposed nozzles, means for movlng a continuous i~perforate web having excess liquid coating thereon length-wise and upwardly between the nozzles in such closely spaced relation to each nozzle as to make the nozzle operative for impinging a stream of fluid under pressure against the web for removing excegs liquid coating from the web and wherein the two opposed streams of fluid under pressure normally cause a heavier liquid coating to remain on the longitudinal marginal portions of the imperforate web after the web has passed the nozzles, the improvement for preventing the accumulation of such heavier costing on the web in which each nozzle compri6es an elongated body member having its length dimension disposed transversely of the length of the web, an elongated plenum chamber enclosed by the body member and extending : along the length thereof, fluid emitting orifice forming means facing toward the web and extend-ing along the length of the body member for connecting the plenum chamber with the exterior af the body member, fluid admission port forming means associated with the body member in fluid communication with the plenum chamber in only an intermediate zone along the length of the plenum chamber, baffle means interposed in the path of fluid moving from the fluid admission port forming means through the plenum chamber and the fluid em~t-ting orifice forming means, the baffle mean~ being shaped to change the direction of movement of fluid passing through the fluid admission port forming mean~ and impinging on the baffle means, and inter~al wall surfaces presented by the plenum chamber shaped to impart to the fluid impinging on the baffle means and moving through each end portion of the fluid emitting orifice forming means movement having a component parallel to the associated surface of the web and in a direction
Abstract of the Invention The present invention is the discovery that fluid from opposing nozzles impinging against a moving web to control the thickness of coat-ing liquid on the web will ameliorate or eliminate edge effect when the fluid has a component of motion toward each edge of the web sufficient to cause excess liquid coating in the vicinity of each edge of the web to have a component of motion toward each edge of the web (in sddition to the component of motion of excess liquid coating downwardly) to thereby obtain substantially uniform liquld coating thickness across the width of the web.
; Additionally applicant has discovered how to construct a fluid no~zle and arrange the same in a liquid coating thickness control appara-~,, tus so as to obtain the desired movement of fluid and coating liquid as ~' Ju~t described and thereby obtain substantially uniform liquid coating ,, 20 thickness across the width of a web.
"~, Accordingly, there is provided in accordance with the present ~:. invention the method of removing excess liquid coating from one surface of a traveling web comprising (a) supplying a source of fluid under .~ pressure, (b) forming a stream of the f]uid, (c) shaping the stream of . fluid so as to form a single, unitary stream which impinges against the one surface of the web across the width thereof to remove excess liquid coating from the one surface, (d) controlling the direction of fluid move-., ment in the stream of fluid impinging against the one surface of the web to cause movement of excess liquid coating on the traveling web outwardly !.~1' ~,~ 30 toward the longitudinal edges of the web.
There is also provided in accordance with the present invention ' '" ~
` A~ ~ 3 ~08~5~1Z
in combination with a palr of opposed nozzles, means for movlng a continuous i~perforate web having excess liquid coating thereon length-wise and upwardly between the nozzles in such closely spaced relation to each nozzle as to make the nozzle operative for impinging a stream of fluid under pressure against the web for removing excegs liquid coating from the web and wherein the two opposed streams of fluid under pressure normally cause a heavier liquid coating to remain on the longitudinal marginal portions of the imperforate web after the web has passed the nozzles, the improvement for preventing the accumulation of such heavier costing on the web in which each nozzle compri6es an elongated body member having its length dimension disposed transversely of the length of the web, an elongated plenum chamber enclosed by the body member and extending : along the length thereof, fluid emitting orifice forming means facing toward the web and extend-ing along the length of the body member for connecting the plenum chamber with the exterior af the body member, fluid admission port forming means associated with the body member in fluid communication with the plenum chamber in only an intermediate zone along the length of the plenum chamber, baffle means interposed in the path of fluid moving from the fluid admission port forming means through the plenum chamber and the fluid em~t-ting orifice forming means, the baffle mean~ being shaped to change the direction of movement of fluid passing through the fluid admission port forming mean~ and impinging on the baffle means, and inter~al wall surfaces presented by the plenum chamber shaped to impart to the fluid impinging on the baffle means and moving through each end portion of the fluid emitting orifice forming means movement having a component parallel to the associated surface of the web and in a direction
3~ toward the associated marginal portion of the web to thereby move liquld coatin~ on the associated marginal portion of the web outwardly and down-` Al ~o wardly relative to the surface of the web.
Brief Descrlption of the Drawings Figure 1 is a fragmentary view in elevation of a liquid coat-lng thickness control system em~odying the present invention and for carrying out the method of the present invention;
Figure 2 is a fragmentary side elevational view of the apparatus of Figure 1 with parts broken away better to illustrate the embodiment;
Figure 3 is a fragmentary view in cross section taken on the line 3--3 of Figure 1 with parts removed for simplification;
Figure 4 iB an exploded view of a nozzle con~tituting an embodi-ment of the present invention;
Figure 5 i8 a fragmentary view in cross section taken on the line 5--S of Figure l;
i Figure 6 i9 a fragmentary view in section taken on the line . 6--6 of Figure l;
~ Figure 7 is a fragmentary view in cross section similar to ii Figure 3 illustrating a modified form of nozzle and i8 located on the sheet containing Flgure 3;
Figure 8 is an exploded view of the modified form of nozzle illustrated in Figure 7;
Figure 9 is a view in cross section similar to Figure 5 of the nozzle of Figure 8;
Figure 10 is a view in cross ~ection similar to Figure 6 of , the nozzle of Figure 8;
;' ; Figure 11 is a view similar to Figures 3 and 7 of a further . modified form of apparatus useful for carrying out the method of the present invention and is located on the sheet containing Figure 3;
Figure 12 is a fragmentary front elevational view of the ~ apparatus of Figure 11 and is located on the sheet containing Figure 3;
:. 30 and Figure 13 is a c~oss sectional Yiew taken on the line 13 - 13 .
-'"` 108~
of Figure 11 and is located on the sheet containing Figure 3.
Detailed Description Although the present invention is applicable to the production of imperforate webs such as coated paper, photographic film and metal strip coated with metals other than zinc, the invention will be described in the environment of continuous galvanizing, the principles of application to the other environments being obvious from the ensuing description of the invention in the galvanizing art.
Referring especially to Figures 1 and 2, steel strip 15 is shown traversing a galvanizing pot 16 holding a spelter bath 17. The path of travel of ~he strip is established by a sequence of guide rolls around which the strip is led. The rolls include sink roll 18 and change-of-direction roll 19, the latter being far enough above the bath so that the molten spelter on the strip has solidified by the time the strip reaches roll 19. A motor driven coiler 20 draws the strip through the galvanizing apparatus. A stabilizing roll 21 near the surface of the spelter bath presents the strip in planar form to a coating thickness control apparatus, indicated generally by reference numeral 22, with uniform spacing between the strip and the coating thickness control nozzles 23 i and 24.
The liquid coating thickness control system involving nozzles 23 ; and 24 and its operation are described in detail in V.S. Patent 3,499,418.
Briefly, strip 15 passing upwardly from the spelter bath carries on each of its surfaces a layer or coating of molten coating metal. In the coating thickness control zone defined by nozzles 23 and 24, the thickness of the coatings on the two sides of strip 15 is controlled by wiping excess coating metal back into the bath 17. This is effected through streams of gas under pressure issuing from the nozzles in accordance with the basic principles taught in V.S. Patent 3,499,418.
~ .
,. . -.. ' ' :
; .
~V8X9~2 Nozzles 23 and 24 form part of a coating thickness control rig whlch includes frame members 26, 26 and associatet ad~ustable nozzle support structures 27, 27 which gupport the nozzles 23, 24 for needed movement with nozzle 23 on one gide of the strip travel path and with nozzle 24 on the opposite side of the travel path at approxi-mately the same height as nozzle 23 with each nozzle facing the associated surface of the steel strip. The nozzles can be identical and therefore descrlption of one nozzle will suffice for an understanding of both.
Referring now to Figures 3 - 6, nozzle 23 has a elongated 1~ body member made up of a lower die 28 and an upper die 29 which as will be further described enclose between them an elongated cavity ; or plenum chamber, indicated generally by reference numeral 31, when - they are assembled as shown in Figures 1, 2, 5 and 6. The upper and lower dies are held together by bolts 30 which are shown in section in Figure 3 and an elongated shim 32 (Figure 4) is positioned between the dies at the ends and rear of the nozzle to form the nozzle fluid emittirg orifice 34 (Figures 5 and 6) through which fluid or gas is emitted from ;, the nozzle to impinge against the liquid coating on the surface of strlp lS. Fluid emitting orifice 34 comprises a long passageway 35 ` 20 having planar walls which are parallel to each other, the length of the passageway from the plenum chamber fluid entrance opening side to the fluid exit opening 6ide being at least several times its wldth or helght ` as deflned by shim 32. Other forms of orlfices can be used if desired.
The plenum chamber 31 enclosed by dies 28 and 29 is shown in the form of nozzle illustrated to be formed by a cavity 36 in die 28 and a cavity indicated generally by reference numeral 38 in die 29, the two cavities acting together to make up the plenum chamber 31 within the nozzle. The cavity 36 in die 28 can be merely an elongated trough with the forward wall ~loping toward the nozzle orifice 34. The cavlty 38 on the other hand, in the illustrated embodiment, has ~imllar end portions 40 corre~ponding in shape inversely to the end portlons of . .
. .
A~
10~3'Z912 cavity 36. However, the central portion of cavity 38 extends rear-wardly of the nozzle to form an enlarged central portion 42 defined by forwardly diverging walls 44 which just clear two of the bolts 30 which hold the dies together. Farthest back from the nozzle orif ice in cavity 42, an elongated inlet gag or fluid admission port 46 opens into cavity 38, inlet gas port 46 having a fluid flow direction per-pendicular to the exposed portion 52 of the upper 6urface 47 of die 28 in that centrally located portion of the plenum chamber formed by enlarged cavity 42 of die 29. Gas admisslon port 46 i6 elongated along the length of tie 29 in order to have as large a gas inlet port as practicable as far back in die 29 as practicable within the limits of the die structures 28 and 29, while still confining the gas inlet port i to the central or intermediate portion of the plenum chamber formed by cavities 36 and 38.
In order to supply gas under pressure to gas inlet port . ..
46 with the gas distributed as uniformly as practicable over the entire area of port 46, conventional high pressure gas or fl~id supply cylindri-cal conduit 48 is connected to ~nlet gas port 46 through a gas flow equalizing chamber 50.
It will be noted that the portion 52 of the planar upper surface 47 of lower die 28 coinciding with portion 42 of cavity 38 forms a baffle, the boundaries of which are defined by walls 44. This baffle 52 is shown disposed at right angles to the flow of gas entering the plenum chamber 30 of the nozzle formed by recesses 36 and 38. In the narrow bodied nozzle of Figures 3 to 6, the diverging angle which walls 44 assume is governed by the two ad~acent bolts 30 which are needed to ~ hold the dies in seallng relationship with each other. Thus this angle ; is made as wide as practicable in the circumstances. On the other hand, where the nozzle can be made deeper or in other words the dles made wider, the mo~e ideal angle shown in the modlfied structure of Figures 7 to 10 can be adopted.
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.. , ,,..~
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It will be evident from the foregoing that the gas or fluid impinging on baffle 52 will have its direction of flow changed and that the internal surfaces of plenum chamber 31, including walls 44, will determine the direction of movement of the gas toward and through fluid emittlng orifice 34 and that this direction of movement of the gas in each end zone of chamber 31 will have an outward compon-ent toward the associated marginal portion of the strip, in addition to - a component toward the surface of the strip.
Since the modified structure of Figures 7 to 10, aside from the angle of walls 44 is the same as that of Figures 1 to 6, a ~ description of this modification has been obviated by assigning the ! same reference numerals to similar parts in the Figures 7 to 10 embodi-ment as in the Figures 3-6 embodiment with 100 being added to each reference numeral in Figures 7 - 10.
Figures 11 to 13 disclose another form of apparatus for carrying out the method of this invention, namely the impingement of gas on the liquid coating on a strip or web to remove excess liquid ; coating in such a way as to move coating laterally of the length of the strip or web toward the marginal portions of the strip or web.
It will be noted that the nozzle 223 of the Figures 11 to 13 modifica-tion is similar to that illustrated in U.S. Patent 3,499,418, Figure
Brief Descrlption of the Drawings Figure 1 is a fragmentary view in elevation of a liquid coat-lng thickness control system em~odying the present invention and for carrying out the method of the present invention;
Figure 2 is a fragmentary side elevational view of the apparatus of Figure 1 with parts broken away better to illustrate the embodiment;
Figure 3 is a fragmentary view in cross section taken on the line 3--3 of Figure 1 with parts removed for simplification;
Figure 4 iB an exploded view of a nozzle con~tituting an embodi-ment of the present invention;
Figure 5 i8 a fragmentary view in cross section taken on the line 5--S of Figure l;
i Figure 6 i9 a fragmentary view in section taken on the line . 6--6 of Figure l;
~ Figure 7 is a fragmentary view in cross section similar to ii Figure 3 illustrating a modified form of nozzle and i8 located on the sheet containing Flgure 3;
Figure 8 is an exploded view of the modified form of nozzle illustrated in Figure 7;
Figure 9 is a view in cross section similar to Figure 5 of the nozzle of Figure 8;
Figure 10 is a view in cross ~ection similar to Figure 6 of , the nozzle of Figure 8;
;' ; Figure 11 is a view similar to Figures 3 and 7 of a further . modified form of apparatus useful for carrying out the method of the present invention and is located on the sheet containing Figure 3;
Figure 12 is a fragmentary front elevational view of the ~ apparatus of Figure 11 and is located on the sheet containing Figure 3;
:. 30 and Figure 13 is a c~oss sectional Yiew taken on the line 13 - 13 .
-'"` 108~
of Figure 11 and is located on the sheet containing Figure 3.
Detailed Description Although the present invention is applicable to the production of imperforate webs such as coated paper, photographic film and metal strip coated with metals other than zinc, the invention will be described in the environment of continuous galvanizing, the principles of application to the other environments being obvious from the ensuing description of the invention in the galvanizing art.
Referring especially to Figures 1 and 2, steel strip 15 is shown traversing a galvanizing pot 16 holding a spelter bath 17. The path of travel of ~he strip is established by a sequence of guide rolls around which the strip is led. The rolls include sink roll 18 and change-of-direction roll 19, the latter being far enough above the bath so that the molten spelter on the strip has solidified by the time the strip reaches roll 19. A motor driven coiler 20 draws the strip through the galvanizing apparatus. A stabilizing roll 21 near the surface of the spelter bath presents the strip in planar form to a coating thickness control apparatus, indicated generally by reference numeral 22, with uniform spacing between the strip and the coating thickness control nozzles 23 i and 24.
The liquid coating thickness control system involving nozzles 23 ; and 24 and its operation are described in detail in V.S. Patent 3,499,418.
Briefly, strip 15 passing upwardly from the spelter bath carries on each of its surfaces a layer or coating of molten coating metal. In the coating thickness control zone defined by nozzles 23 and 24, the thickness of the coatings on the two sides of strip 15 is controlled by wiping excess coating metal back into the bath 17. This is effected through streams of gas under pressure issuing from the nozzles in accordance with the basic principles taught in V.S. Patent 3,499,418.
~ .
,. . -.. ' ' :
; .
~V8X9~2 Nozzles 23 and 24 form part of a coating thickness control rig whlch includes frame members 26, 26 and associatet ad~ustable nozzle support structures 27, 27 which gupport the nozzles 23, 24 for needed movement with nozzle 23 on one gide of the strip travel path and with nozzle 24 on the opposite side of the travel path at approxi-mately the same height as nozzle 23 with each nozzle facing the associated surface of the steel strip. The nozzles can be identical and therefore descrlption of one nozzle will suffice for an understanding of both.
Referring now to Figures 3 - 6, nozzle 23 has a elongated 1~ body member made up of a lower die 28 and an upper die 29 which as will be further described enclose between them an elongated cavity ; or plenum chamber, indicated generally by reference numeral 31, when - they are assembled as shown in Figures 1, 2, 5 and 6. The upper and lower dies are held together by bolts 30 which are shown in section in Figure 3 and an elongated shim 32 (Figure 4) is positioned between the dies at the ends and rear of the nozzle to form the nozzle fluid emittirg orifice 34 (Figures 5 and 6) through which fluid or gas is emitted from ;, the nozzle to impinge against the liquid coating on the surface of strlp lS. Fluid emitting orifice 34 comprises a long passageway 35 ` 20 having planar walls which are parallel to each other, the length of the passageway from the plenum chamber fluid entrance opening side to the fluid exit opening 6ide being at least several times its wldth or helght ` as deflned by shim 32. Other forms of orlfices can be used if desired.
The plenum chamber 31 enclosed by dies 28 and 29 is shown in the form of nozzle illustrated to be formed by a cavity 36 in die 28 and a cavity indicated generally by reference numeral 38 in die 29, the two cavities acting together to make up the plenum chamber 31 within the nozzle. The cavity 36 in die 28 can be merely an elongated trough with the forward wall ~loping toward the nozzle orifice 34. The cavlty 38 on the other hand, in the illustrated embodiment, has ~imllar end portions 40 corre~ponding in shape inversely to the end portlons of . .
. .
A~
10~3'Z912 cavity 36. However, the central portion of cavity 38 extends rear-wardly of the nozzle to form an enlarged central portion 42 defined by forwardly diverging walls 44 which just clear two of the bolts 30 which hold the dies together. Farthest back from the nozzle orif ice in cavity 42, an elongated inlet gag or fluid admission port 46 opens into cavity 38, inlet gas port 46 having a fluid flow direction per-pendicular to the exposed portion 52 of the upper 6urface 47 of die 28 in that centrally located portion of the plenum chamber formed by enlarged cavity 42 of die 29. Gas admisslon port 46 i6 elongated along the length of tie 29 in order to have as large a gas inlet port as practicable as far back in die 29 as practicable within the limits of the die structures 28 and 29, while still confining the gas inlet port i to the central or intermediate portion of the plenum chamber formed by cavities 36 and 38.
In order to supply gas under pressure to gas inlet port . ..
46 with the gas distributed as uniformly as practicable over the entire area of port 46, conventional high pressure gas or fl~id supply cylindri-cal conduit 48 is connected to ~nlet gas port 46 through a gas flow equalizing chamber 50.
It will be noted that the portion 52 of the planar upper surface 47 of lower die 28 coinciding with portion 42 of cavity 38 forms a baffle, the boundaries of which are defined by walls 44. This baffle 52 is shown disposed at right angles to the flow of gas entering the plenum chamber 30 of the nozzle formed by recesses 36 and 38. In the narrow bodied nozzle of Figures 3 to 6, the diverging angle which walls 44 assume is governed by the two ad~acent bolts 30 which are needed to ~ hold the dies in seallng relationship with each other. Thus this angle ; is made as wide as practicable in the circumstances. On the other hand, where the nozzle can be made deeper or in other words the dles made wider, the mo~e ideal angle shown in the modlfied structure of Figures 7 to 10 can be adopted.
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- ` ~082g1Z
It will be evident from the foregoing that the gas or fluid impinging on baffle 52 will have its direction of flow changed and that the internal surfaces of plenum chamber 31, including walls 44, will determine the direction of movement of the gas toward and through fluid emittlng orifice 34 and that this direction of movement of the gas in each end zone of chamber 31 will have an outward compon-ent toward the associated marginal portion of the strip, in addition to - a component toward the surface of the strip.
Since the modified structure of Figures 7 to 10, aside from the angle of walls 44 is the same as that of Figures 1 to 6, a ~ description of this modification has been obviated by assigning the ! same reference numerals to similar parts in the Figures 7 to 10 embodi-ment as in the Figures 3-6 embodiment with 100 being added to each reference numeral in Figures 7 - 10.
Figures 11 to 13 disclose another form of apparatus for carrying out the method of this invention, namely the impingement of gas on the liquid coating on a strip or web to remove excess liquid ; coating in such a way as to move coating laterally of the length of the strip or web toward the marginal portions of the strip or web.
It will be noted that the nozzle 223 of the Figures 11 to 13 modifica-tion is similar to that illustrated in U.S. Patent 3,499,418, Figure
4 but instead of a shim being used to space the component dies making up the nozzle, the wall forming the passageway of the fluid emitting orifice in the upper die has portions milled out to form streamlined vanes 60. The gas passes out through the milled-out portions and vanes 60 are shaped to change the direction of the gas so that the gas impinges on the liquid coating on the web with an outwardly sweeping motion. Vanes 60 are shown exaggerated in thickness in the drawing;
their width should be extremely narrow so as not to break down the - 30 single wite stream of gas into di~crete streams. Obvlously vanes 60 , constitute baffle means disposed in the path of the gas passing through ~, -8-A~
- 1082~12 the nozzle.
The following table gives examples of satisfactory gas pressures, nozzle-to-strip spacings and ranges of important nozzle dimensions.
Inches cm Nozzle-to-strip Spacing l/4 - l-1/2 .635-3.81 ~ozzle Fluid Exit Opening Width (or height) .010-.15 .0254-.381 Nozzle Fluid Exit Length Opening 30 - 72 76.2-182.88 Nozzle Pluid Inlet Port Width 1/2 - 1 1.27-2.54 Nozzle Fluid Inlet Port Length 8 - 16 20.32-40.64 Fluid Supply Conduit Diameter 1 - 2 2.54-5.08 lb/in2Kg/cm2 Fluid Pressure 5 - 80.352-5.624 The foregoing described liquid coating thickness control apparatus of Figures 1 to 6 has been found by applicant to do a very sati~factory Job in galvanizing at moderate strip speeds and gas pressures. The nozzle modification illustrated in Figures 7 to lO
is even more efficacious in view of the wider fluid diffusing action of wall portions 144. However, other forms of nozzles incorporating principles of the present invention can be used, similar to those illustrated in Figures 1 to 10, and not as radically different as thst illustrated in Figures ll to 13. Such other nozzles would have one central fluid inlet port to a plenum ch~mber, such as fluid inlet ports 46 and 146, but with the nozzle made still deeper the fluid " inlet port could be farther back from the nozzle oriflce and need not be so elongated, if elongated at all. In such case, walls the e~ul-valent of wallR 144 would have a smaller angle in respect to each other.
~t ` - ` 1082g~2 An advantage of the nozzle structures of Figures 1 to 10 which would be lost by such other modified forms would be the broad stream of incoming gas, shaped by fluid admission ports 46 and 146 so as to have a long dimension along the length of the - nozzle orifice and therefore across the width of the web, together with the resulting distribution of the highest pressure zone in the plenum chamber over a longer portion of the length of the nozzle orifice. From inspection of Figures 4 to 10, it will be apparent that the smallest cross sectional area of each of the fluid admis- -sion ports 46 and 146 has a length dimension several times its width ,:
dimension. In a compact nozzle, the beneficial effects of the elongated fluid inlet port on the over-all uniformity of liquid , coating removal across the width of the web is of importance in practice. Although applicant is not to be limited to the theory - involved, it is believed this is because the mass impact effec~of the incoming flow of fluid into the plenum chamber at any point along the length of the entrance to the fluid emitting orifice varies as the square of the distance between that point and the nearest point of the fluid inlet port. Thus by having an elongated fluid inlet port extending parallel to the nozzle orifice, the mass impact effect of the moving gas in the plenum chamber iR uniformly `- distributed over a wide portion of the nozzle fluid emitting orifice ':
and this in turn tends to keep the central portion of the web from having a final coating thickness which is objectionably less than the remainder of the width of the web. It will be recognized that : .:
in every-day practice a slightly thinner coating in the intermediate portion of the web need not necessarily be ob~ectionable.
The baffle means in the plenum chamber formed by surface 52 is shown as being coplanar with the plane of symmetry of the fluid emitting orifice passageway and this is believed by the applicant ., A' ;: .
- 1~)82912 ; to result in optimum operation. However, satisfactory operation could be achleved with the lower die 28 or 128 being milled out so as to form a cavity in the lower die which is the same shape as cavity 38 or 138. In such case the baffle means would be the floor of the additionally milled out portion of lower die 28 or 128 corresponding to cavity area 47 or 147 in the illugtrated embodiments.
Optimum results are achieved with the nozzles of the present invention when the smallest cross-sectional area of the fluid admission port is several times greater than the smallest cross sectional area of the fluid emitting orifice.
It has already been proposed in the galvanizing art to eliminate edge effect by the utilization of a nozzle which curves toward the strip from the central portion of the web to the edge portions of the web. This type of nozzle has not eliminated ob~ect- -ionable edge effect because edge effect is caused by a heavy coating on the web very close to the edge. What the curved nozzle probably does is to increase the thickness of the coating on the web in the '~ central portion of the web and this thicker coating in the central portion of the web has prevented spooling by virtue of the exces~ -coating on the central portion of the web preventing the strip from assuming the concave configuration which is the objectionable feature of spooling. This excess coating is otherwise wasted, an expensive expedient.
Where under some operating conditions there would be too much removal of liquid coating in the central portion of the web p with applicant's nozzle, the fault can be remedied by imparting to applicant's nozzle a so-called curved shape, with the amount of curvature such as to build up the central portion of the coating on the web to the desired thickness, not an excess thickness. Thus the nozzles of Figures 4 and 8 can where desired be given a curva-~;A' ~(18~2 ' ture which will result in a satisfsctory coating thickness across the width of the web and applicant has operated with this form of nozzle. The tegree of curvature was so slight as not to be evident in the accompanying drawings. In applicant 16 operationg using the so-called curved no~zle, with the form of nozzle illustrated in ~igure 4, the central 18 inch portion of the orifice of the nozzle was straight and parallel to the strip; the next 18 inch portion (9 to 27 inches from the center of the nozzle) of the orifice was tapered along a straight line departing 1/4 of an inch per foot toward the strip from the straight central portion of the orifice.
The outermost 3 inch portion of the nozzle orifice was again straight in a line parallel to the central portion of the nozzle ; orifice. Thus the 18 inch central portion of the nozzle orifice was 0.375 inch farther removed from the strip than the edge por-;~ tions or in other words the central portion of the fluid emitting orifice is spaced rearwardly from a straight line extending between the ents of the fluid emitting orifice. This ~o-called curved die , was representatlve of applicant's invention but the dimenslons of ~, . taper can be changed to accommodate the parameters involved, includ-ing speed of the strip, distance of travel of the fluid from the ~; nozzle to the strip, the pressure of the fluid, so as to obtain the optimum practical uniformity of the liquid coating thlckness across the width of the strip.
~`
Of course where the central portion of the strip would ` have a thinner coating over say a 12-inch portion, the central portion of the nozzle would be~spaced away from the strip over a length of nozzle orifice and at a distance from the strip which ' ~' :
~os2g~2 would result in a commercially satisfactory uniformity of coat- :
ing thickness across the width of the strip. The important aspect is that the so-called curved die configuration can ade-quately control the coating thickness except for edge effect and since applicant's outwardly sweeping gas flow can control edge effect, the two phenomena can be combined where desirable to solve any coating thickness uniformity problem within practical limits.
;
., ,~
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'.' .:
~o829~2 . .
SUPPLEMENTARY DISCLOSURE
In the Principal Disclosure there is described an apparatus and method for controlling the thickness of a coating applied to a moving web of material, with particular but not exclusive reference to continuous galvaniz-ing of steel strip. In this apparatus and method, excess coating material is wiped back into the bath by streams of gas under pressure issuing from a pair of nozzles situated on opposite sides of the strip or web at approximately the same height with each nozzle facing the associated surface of the strip. U.S.
Patent 3,499,418suggests that the jets should be horizontally opposed and the gas emerging therefrom should impinge upon the upwardly moving strip or web in - a substantially perpendicular fashion, although a maximum downward impingement angle of 5 and an upward angle somewhat greater than 5 can be tolerated.
It has now been found, however, that the nozzles may be inclined upwardly or downwardly as much as 15 and need not be coplanar and yet still achieve the objects of the present invention. If the nozzles are not coplanar, i.e. one nozzle is slightly higher than the other, then it is desirable that . .
provision is made to shield the nozzle orifice in order to prevent plugging by molten metal or the like.
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: - - 14 -.
' ., :~
their width should be extremely narrow so as not to break down the - 30 single wite stream of gas into di~crete streams. Obvlously vanes 60 , constitute baffle means disposed in the path of the gas passing through ~, -8-A~
- 1082~12 the nozzle.
The following table gives examples of satisfactory gas pressures, nozzle-to-strip spacings and ranges of important nozzle dimensions.
Inches cm Nozzle-to-strip Spacing l/4 - l-1/2 .635-3.81 ~ozzle Fluid Exit Opening Width (or height) .010-.15 .0254-.381 Nozzle Fluid Exit Length Opening 30 - 72 76.2-182.88 Nozzle Pluid Inlet Port Width 1/2 - 1 1.27-2.54 Nozzle Fluid Inlet Port Length 8 - 16 20.32-40.64 Fluid Supply Conduit Diameter 1 - 2 2.54-5.08 lb/in2Kg/cm2 Fluid Pressure 5 - 80.352-5.624 The foregoing described liquid coating thickness control apparatus of Figures 1 to 6 has been found by applicant to do a very sati~factory Job in galvanizing at moderate strip speeds and gas pressures. The nozzle modification illustrated in Figures 7 to lO
is even more efficacious in view of the wider fluid diffusing action of wall portions 144. However, other forms of nozzles incorporating principles of the present invention can be used, similar to those illustrated in Figures 1 to 10, and not as radically different as thst illustrated in Figures ll to 13. Such other nozzles would have one central fluid inlet port to a plenum ch~mber, such as fluid inlet ports 46 and 146, but with the nozzle made still deeper the fluid " inlet port could be farther back from the nozzle oriflce and need not be so elongated, if elongated at all. In such case, walls the e~ul-valent of wallR 144 would have a smaller angle in respect to each other.
~t ` - ` 1082g~2 An advantage of the nozzle structures of Figures 1 to 10 which would be lost by such other modified forms would be the broad stream of incoming gas, shaped by fluid admission ports 46 and 146 so as to have a long dimension along the length of the - nozzle orifice and therefore across the width of the web, together with the resulting distribution of the highest pressure zone in the plenum chamber over a longer portion of the length of the nozzle orifice. From inspection of Figures 4 to 10, it will be apparent that the smallest cross sectional area of each of the fluid admis- -sion ports 46 and 146 has a length dimension several times its width ,:
dimension. In a compact nozzle, the beneficial effects of the elongated fluid inlet port on the over-all uniformity of liquid , coating removal across the width of the web is of importance in practice. Although applicant is not to be limited to the theory - involved, it is believed this is because the mass impact effec~of the incoming flow of fluid into the plenum chamber at any point along the length of the entrance to the fluid emitting orifice varies as the square of the distance between that point and the nearest point of the fluid inlet port. Thus by having an elongated fluid inlet port extending parallel to the nozzle orifice, the mass impact effect of the moving gas in the plenum chamber iR uniformly `- distributed over a wide portion of the nozzle fluid emitting orifice ':
and this in turn tends to keep the central portion of the web from having a final coating thickness which is objectionably less than the remainder of the width of the web. It will be recognized that : .:
in every-day practice a slightly thinner coating in the intermediate portion of the web need not necessarily be ob~ectionable.
The baffle means in the plenum chamber formed by surface 52 is shown as being coplanar with the plane of symmetry of the fluid emitting orifice passageway and this is believed by the applicant ., A' ;: .
- 1~)82912 ; to result in optimum operation. However, satisfactory operation could be achleved with the lower die 28 or 128 being milled out so as to form a cavity in the lower die which is the same shape as cavity 38 or 138. In such case the baffle means would be the floor of the additionally milled out portion of lower die 28 or 128 corresponding to cavity area 47 or 147 in the illugtrated embodiments.
Optimum results are achieved with the nozzles of the present invention when the smallest cross-sectional area of the fluid admission port is several times greater than the smallest cross sectional area of the fluid emitting orifice.
It has already been proposed in the galvanizing art to eliminate edge effect by the utilization of a nozzle which curves toward the strip from the central portion of the web to the edge portions of the web. This type of nozzle has not eliminated ob~ect- -ionable edge effect because edge effect is caused by a heavy coating on the web very close to the edge. What the curved nozzle probably does is to increase the thickness of the coating on the web in the '~ central portion of the web and this thicker coating in the central portion of the web has prevented spooling by virtue of the exces~ -coating on the central portion of the web preventing the strip from assuming the concave configuration which is the objectionable feature of spooling. This excess coating is otherwise wasted, an expensive expedient.
Where under some operating conditions there would be too much removal of liquid coating in the central portion of the web p with applicant's nozzle, the fault can be remedied by imparting to applicant's nozzle a so-called curved shape, with the amount of curvature such as to build up the central portion of the coating on the web to the desired thickness, not an excess thickness. Thus the nozzles of Figures 4 and 8 can where desired be given a curva-~;A' ~(18~2 ' ture which will result in a satisfsctory coating thickness across the width of the web and applicant has operated with this form of nozzle. The tegree of curvature was so slight as not to be evident in the accompanying drawings. In applicant 16 operationg using the so-called curved no~zle, with the form of nozzle illustrated in ~igure 4, the central 18 inch portion of the orifice of the nozzle was straight and parallel to the strip; the next 18 inch portion (9 to 27 inches from the center of the nozzle) of the orifice was tapered along a straight line departing 1/4 of an inch per foot toward the strip from the straight central portion of the orifice.
The outermost 3 inch portion of the nozzle orifice was again straight in a line parallel to the central portion of the nozzle ; orifice. Thus the 18 inch central portion of the nozzle orifice was 0.375 inch farther removed from the strip than the edge por-;~ tions or in other words the central portion of the fluid emitting orifice is spaced rearwardly from a straight line extending between the ents of the fluid emitting orifice. This ~o-called curved die , was representatlve of applicant's invention but the dimenslons of ~, . taper can be changed to accommodate the parameters involved, includ-ing speed of the strip, distance of travel of the fluid from the ~; nozzle to the strip, the pressure of the fluid, so as to obtain the optimum practical uniformity of the liquid coating thlckness across the width of the strip.
~`
Of course where the central portion of the strip would ` have a thinner coating over say a 12-inch portion, the central portion of the nozzle would be~spaced away from the strip over a length of nozzle orifice and at a distance from the strip which ' ~' :
~os2g~2 would result in a commercially satisfactory uniformity of coat- :
ing thickness across the width of the strip. The important aspect is that the so-called curved die configuration can ade-quately control the coating thickness except for edge effect and since applicant's outwardly sweeping gas flow can control edge effect, the two phenomena can be combined where desirable to solve any coating thickness uniformity problem within practical limits.
;
., ,~
' ' `::
'.' .:
~o829~2 . .
SUPPLEMENTARY DISCLOSURE
In the Principal Disclosure there is described an apparatus and method for controlling the thickness of a coating applied to a moving web of material, with particular but not exclusive reference to continuous galvaniz-ing of steel strip. In this apparatus and method, excess coating material is wiped back into the bath by streams of gas under pressure issuing from a pair of nozzles situated on opposite sides of the strip or web at approximately the same height with each nozzle facing the associated surface of the strip. U.S.
Patent 3,499,418suggests that the jets should be horizontally opposed and the gas emerging therefrom should impinge upon the upwardly moving strip or web in - a substantially perpendicular fashion, although a maximum downward impingement angle of 5 and an upward angle somewhat greater than 5 can be tolerated.
It has now been found, however, that the nozzles may be inclined upwardly or downwardly as much as 15 and need not be coplanar and yet still achieve the objects of the present invention. If the nozzles are not coplanar, i.e. one nozzle is slightly higher than the other, then it is desirable that . .
provision is made to shield the nozzle orifice in order to prevent plugging by molten metal or the like.
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: - - 14 -.
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Claims (37)
1. In combination with a pair of opposed nozzles, means for moving a continuous imperforate web having excess liquid coating thereon lengthwise and upwardly between the nozzles in such closely spaced relation to each nozzle as to make the nozzle operative for impinging a stream of fluid under pressure against the web for removing excess liquid coating from the web and wherein the two opposed streams of fluid under pressure normally cause a heavier liquid coating to remain on the longitudinal marginal portions of the imperforate web after the web has passed the nozzles, the improvement for preventing the accumulation of such heavier coating on the web in which each nozzle comprises an elongated body member having its length dimension disposed transversely of the length of the web, an elongated plenum chamber enclosed by the body member and extending along the length thereof, fluid emitting orifice forming means facing toward the web and extending along the length of the body member for connecting the plenum chamber with the exterior of the body member, fluid admission port forming means associated with the body member in fluid communication with the plenum chamber in only an intermediate zone along the length of the plenum chamber, baffle means interposed in the path of fluid moving from the fluid admission port forming means through the plenum chamber and the fluid emitting orifice forming means, the baffle means being shaped to change the direction of movement of fluid passing through the fluid admission port forming means and impinging on the baffle means, and internal wall surfaces presented by the plenum chamber shaped to impart to the fluid impinging on the baffle means and moving through each end portion of the fluid emitting orifice forming means movement having a component parallel to the associated surface of the web ant in a direction toward the associated marginal portion of the web to thereby move liquid coating on the associated marginal portion of the web outwardly and downwardly relative to the surface of the web.
2. The apparatus of claim 1 in which the fluid admission port forming means is elongated in the direction of the length of the body member, the smallest cross-sectional area of the fluid admission port forming means having a length dimension at least several times the width dimension of such area.
3. The apparatus of claim 2 in which the fluid emitting orifice forming means comprises a fluid entrance opening forming means extending along the length of the plenum chamber, fluid exit opening forming means extending along the exterior of the body member, and passageway forming means extending between and connecting the fluid entrance forming means and the fluid exit forming means, the pass-ageway having greater length in a direction normal to the length of the orifice than width in a direction normal to the length of the orifice.
4. The apparatus of claim 3 in which the passageway forming means has a plane of symmetry, and the baffle means has a planar surface parallel to or coplanar with the plane of symmetry of the passageway.
5. The apparatus of claim 1, 2 or 3 in which the passageway forming means comprises parallel, planar longitudinal walls.
6. The apparatus of claim 4 in which the passageway forming means comprises parallel, planar longitudinal walls.
7. The apparatus of claim 1, 2 or 3 in which the smallest cross-sectional area of the fluid admission port forming means is several times as great as the smallest cross-sectional area of the fluid emitting orifice forming means.
8. The apparatus of claim 6 in which the smallest cross-sectional area of the fluid admission port forming means is several times as great as the smallest cross-sectional area of the fluid emitting orifice forming means.
9. The apparatus of claim l, 2 or 3 in which there are cylindrical conduit means for supplying the fluid to the fluid admission port forming means, and chamber means connect the cylindrical conduit means and the fluid admission port forming means, the chamber means being shaped to distribute the fluid flow from the cylindrical conduit means substanti-ally uniformly across the cross-sectional area of the fluid admission port forming means.
10. The apparatus of claim 8 in which there are cylindrical conduit means for supplying the fluid to the fluid admission port forming means, and chamber means connect the cylindrical conduit means and the fluid admission port forming means, the chamber means being shaped to distribute the fluid flow from the cylindrical conduit means substantially uniformly across the cross-sectional area of the fluid admission port forming means.
11. The apparatus of claim 1, 2 or 3 in which the baffle means has a planar surface extending linearly of the plenum chamber, and the fluid admission port forming means is arranged to introduce the stream of fluid into the plenum chamber in a direction normal to the plane of the baffle means and normal to the direction of fluid pass-ing through the fluid emitting orifice forming means.
12. The apparatus of claim 10 in which the baffle means has a planar surface extending linearly of the plenum chamber, and the fluid admission port forming means is arranged to introduce the stream of fluid into the plenum chamber in a direction normal to the plane of the baffle means and normal to the direction of fluid pass-ing through the fluid emitting orifice forming means.
13. The apparatus of claim 1, 2 or 3 in which the smallest cross-sectional area of the fluid admission port forming means has a length dimension about 8 to about 32 times the width dimension of such area.
14. The apparatus of claim 12 in which the smallest cross-sectional area of the fluid admission port forming means has a length dimension about 8 to about 32 times the width dimension of such area.
15. The apparatus of claim 1, 2 or 3 in which the length dimension of the smallest cross-sectional area of the fluid admission port forming means is between about 1/10 and about 1/2 the length of the fluid emitting orifice forming means.
16. The apparatus of claim 14 in which the length dimension of the smallest cross-sectional area of the fluid admission port forming means is between about 1/10 and about 1/2 the length of the fluid emitting orifice forming means.
17. The apparatus of claim 1, 2 or 3 in which the baffle means extends at least the full length and width of the fluid admission port forming means.
18. The apparatus of claim 16 in which the baffle means extends at least the full length and width of the fluid admission port forming means.
19. The apparatus of claim 1, 2 or 3 in which the width dimension of the fluid emitting orifice in planes normal to the length of the body member is uniform along the length of the fluid emitting orifice and is between 0.005 and 0.15 inches.
20. The apparatus of claim 18, in which the width dimension of the fluid emitting orifice in planes normal to the length of the body member is uniform along the length of the fluid emitting orifice and is between 0.005 and 0.15 inches.
21. The apparatus of claim 1, 2 or 3 in which the baffle means is located in the plenum chamber in spaced relation to the fluid emitting slot forming means.
22. The apparatus of claim 20 in which the baffle means is located in the plenum chamber in spaced relation to the fluid emitting slot forming means.
23. The apparatus of claim 1, 2 or 3 in which the fluid admission port forming means faces the portion of the baffle means farthest remote from the fluid emitting orifice forming means.
24. The apparatus of claim 22 in which the fluid admission port forming means faces the portion of the baffle means farthest remote from the fluid emitting orifice forming means.
25. The apparatus of claim 1, 2 or 3 in which the plenum chamber has in planes normal to the length of the body member a zone of maximum cross-sectional area in the intermediate portion of the body member extending along the length of the fluid admission port forming means and a smaller cross-sectional area in each end portion of the body member, the cross-sectional area of the plenum chamber in each end portion of the body member decreasing uniformly in area from the maximum toward each end portion of the body member.
26. The apparatus of claim 24 in which the plenum chamber has in planes normal to the length of the body member a zone of maximum cross-sectional area in the intermediate portion of the body member extending along the length of the fluid admission port forming means and a smaller cross-sectional area in each end portion of the body member, the cross-sectional area of the plenum chamber in each end portion of the body member decreasing uniformly in area from the maximum toward each end portion of the body member.
27. The apparatus of claim 1, 2 or 3 in which the central portion of the fluid emitting orifice forming means is spaced rearwardly from a straight line extending between the ends of the fluid emitting orifice forming means.
28. The apparatus of claim 26 in which the central portion of the fluid emitting orifice forming means is spaced rearwardly from a straight line extending between the ends of the fluid emitting orifice forming means.
29. The method of removing excess liquid coating from both surfaces of a travelling web issuing from a bath of liquid coating of the type that will harden to form a solid coating on a substrate comprising supplying fluid under pressure, forming two substantially opposed streams of the fluid, one directed toward each surface of the web, shaping each stream of fluid so as to form a continuous stream which impinges against the associated surface of the web across the width thereof at least from one longitudinal edge to the other longitudinal edge to remove excess liquid coating from the associated surface, determining the direction of fluid movement in each stream of fluid im-pinging against an associated surface of the web to cause movement of excess liquid coating on the marginal portions of the associated surface of the travelling web outwardly toward the respective associated longitudinal edges of the web.
30. A method of removing excess liquid coating from both surfaces of a moving, continuous imperforate web issuing from a bath of liquid coating of the type that will harden to form a solid coating on a substate while preventing objectionable residual heavier liquid coating from remaining on the longitud-inal marginal portions of the surfaces of the web comprising:
providing fluid under pressure, forming a pair of opposed streams of fluid under pressure arranged respectively on each of the opposite surfaces of the moving web, forming each stream of the pair of opposed streams of fluid under pressure in a nozzle having an elongated plenum chamber and a fluid emitting orifice forming means having an opening facing toward the associated surface of the web and extending across the width of the associated surface of the web for connecting the plenum chamber with the exterior of the nozzle so as to form a continuous stream extending across the width of the associated surface of the moving web at least from one longitudinal edge to the other longitudinal edge of the web, impinging the opposed streams of fluid under pressure respectively against the associated opposite surfaces of the moving web to remove excess liquid coating from the opposite surfaces of the web, determining the direction of movement of the fluid under pressure in each stream by shaping each stream of fluid under pressure in the nozzle, the direction of movement of the fluid under pressure in each stream being determined at least in part by admitting fluid under pressure into the intermediate portion only of the elongated plenum to cause the fluid under pressure in each end portion of the plenum chamber to have a component of motion parallel to the length dimension of the plenum chamber and a component of motion normal to the associated surface of the web to thereby impart to the fluid under pressure issuing from the fluid emit-ting orifice forming means and impinging on the two marginal portions of the associated surface of the web movement in respect to each marginal portion having a component normal to the surface of the marginal portion of the web and a component parallel to the surface of the marginal portion of the web and in a direction toward the associated longitudinal edge of the web to cause movement of excess liquid coating on the surface of each of the two marginal portions of the web downwardly and outwardly toward the respective longitudinal edges of the web to thereby eliminate objectionable residual heavier liquid coat-ing on the longitudinal marginal portions of the surfaces of the web.
providing fluid under pressure, forming a pair of opposed streams of fluid under pressure arranged respectively on each of the opposite surfaces of the moving web, forming each stream of the pair of opposed streams of fluid under pressure in a nozzle having an elongated plenum chamber and a fluid emitting orifice forming means having an opening facing toward the associated surface of the web and extending across the width of the associated surface of the web for connecting the plenum chamber with the exterior of the nozzle so as to form a continuous stream extending across the width of the associated surface of the moving web at least from one longitudinal edge to the other longitudinal edge of the web, impinging the opposed streams of fluid under pressure respectively against the associated opposite surfaces of the moving web to remove excess liquid coating from the opposite surfaces of the web, determining the direction of movement of the fluid under pressure in each stream by shaping each stream of fluid under pressure in the nozzle, the direction of movement of the fluid under pressure in each stream being determined at least in part by admitting fluid under pressure into the intermediate portion only of the elongated plenum to cause the fluid under pressure in each end portion of the plenum chamber to have a component of motion parallel to the length dimension of the plenum chamber and a component of motion normal to the associated surface of the web to thereby impart to the fluid under pressure issuing from the fluid emit-ting orifice forming means and impinging on the two marginal portions of the associated surface of the web movement in respect to each marginal portion having a component normal to the surface of the marginal portion of the web and a component parallel to the surface of the marginal portion of the web and in a direction toward the associated longitudinal edge of the web to cause movement of excess liquid coating on the surface of each of the two marginal portions of the web downwardly and outwardly toward the respective longitudinal edges of the web to thereby eliminate objectionable residual heavier liquid coat-ing on the longitudinal marginal portions of the surfaces of the web.
31. A method of removing excess liquid coating from both surfaces of a moving, continuous imperforate web issuing from a bath of liquid coating of the type that will harden to form a solid coating on a substrate while preventing objectionable residual heavier liquid coating from remaining on the longitud-inal marginal portions of the surfaces of the web comprising:
providing fluid under pressure, forming a pair of opposed streams of fluid under pressure arranged respectively on each of the opposite surfaces of the moving web, forming each stream of the pair of opposed streams of fluid under pressure in a nozzle having a plenum chamber and a fluid emitting orifice forming means having an opening facing toward the associated surface of the web and extending across the width of the associated surface of the web for connecting the plenum chamber with the exterior of the nozzle so as to form a continuous stream extending across the width of the associated surface of the moving web at least from one longitud-inal edge of the other longitudinal edge of the web, impinging the opposed streams of fluid under pressure respectively against the associated opposite surfaces of the moving web to remove excess liquid coating from the opposite surfaces of the web, determining the direction of movement of the fluid under pressure in each stream by shaping each stream of fluid under pressure in the nozzle, the direction of movement of the fluid under pressure in each stream being determined at least in part by admitting the fluid under preesure into the plenum chamber and impinging fluid under pressure against baffle means disposed in the path of fluid under pressure as the fluid under pressure passes through the nozzle to change the direction of movement of fluid under pressure, and cause the fluid under pressure leaving each end portion of the fluid emitting orifice forming means to have a component of motion parallel to the length dimension of the plenum chamber and a component of motion normal to the associated surface of the web to thereby impart to the fluid under pressure impinging on the two marginal portions of the associated surface of the web movement in respect to each marginal portion having a component normal to the surface of the marginal portion of the web and a component parallel to the surface of the marginal portion of the web and in a direction toward the associated longitudinal edge of the web to cause movement of excess liquid coating on the surface of each of the two marginal portions of the web downwardly and outwardly toward the respective longitudinal edges of the web to thereby eliminate objection-able residual heavier liquid coating on the longitudinal marginal portions of the web.
providing fluid under pressure, forming a pair of opposed streams of fluid under pressure arranged respectively on each of the opposite surfaces of the moving web, forming each stream of the pair of opposed streams of fluid under pressure in a nozzle having a plenum chamber and a fluid emitting orifice forming means having an opening facing toward the associated surface of the web and extending across the width of the associated surface of the web for connecting the plenum chamber with the exterior of the nozzle so as to form a continuous stream extending across the width of the associated surface of the moving web at least from one longitud-inal edge of the other longitudinal edge of the web, impinging the opposed streams of fluid under pressure respectively against the associated opposite surfaces of the moving web to remove excess liquid coating from the opposite surfaces of the web, determining the direction of movement of the fluid under pressure in each stream by shaping each stream of fluid under pressure in the nozzle, the direction of movement of the fluid under pressure in each stream being determined at least in part by admitting the fluid under preesure into the plenum chamber and impinging fluid under pressure against baffle means disposed in the path of fluid under pressure as the fluid under pressure passes through the nozzle to change the direction of movement of fluid under pressure, and cause the fluid under pressure leaving each end portion of the fluid emitting orifice forming means to have a component of motion parallel to the length dimension of the plenum chamber and a component of motion normal to the associated surface of the web to thereby impart to the fluid under pressure impinging on the two marginal portions of the associated surface of the web movement in respect to each marginal portion having a component normal to the surface of the marginal portion of the web and a component parallel to the surface of the marginal portion of the web and in a direction toward the associated longitudinal edge of the web to cause movement of excess liquid coating on the surface of each of the two marginal portions of the web downwardly and outwardly toward the respective longitudinal edges of the web to thereby eliminate objection-able residual heavier liquid coating on the longitudinal marginal portions of the web.
32. In combination with a pair of opposed nozzles, a bath of liquid coating which will harden to form a solid coating on a substrate, means for moving a continuous imperforate web lengthwise through the bath of liquid coating, the web issuing from the bath having excess liquid coating thereon and means for moving the coated strip upwardly between the nozzles in such closely spaced relation to each nozzle as to make the nozzle operative for impinging a stream of fluid under pressure against the web for removing excess liquid coating from the web and wherein the two opposed streams of fluid under pressure normally cause a heavier liquid coating to remain on the longitudinal marginal portions of the imperforate web after the web has passed the nozzles, the improvement for preventing the accumul-ation of such heavier coating on the web in which each nozzle comprises:
a body member, a chamber enclosed by the body member, fluid discharge orifice forming means extending along one dimension of the body member for placing the chamber in communication with the exterior of the body member, the fluid discharge orifice forming means facing toward the web and disposed transversely of the length of the web, fluid inlet port forming means associated with the body member in fluid communication with the chamber, baffle means interposed in the path of fluid moving from the fluid inlet port forming means through the chamber and the fluid discharge orifice forming means to determine the direction of movement of fluid passing through the fluid dis-charge orifice forming means, the baffle means being shaped to impart to fluid impinging on the baffle means and moving through each end portion of the fluid discharge orifice forming means movement having a compon-ent parallel to the associated surface of the web and in a direction toward the associated marginal portion of the web to thereby move liquid coating on the associated marginal portion of the web outwardly and downwardly relative to the surface of the web.
a body member, a chamber enclosed by the body member, fluid discharge orifice forming means extending along one dimension of the body member for placing the chamber in communication with the exterior of the body member, the fluid discharge orifice forming means facing toward the web and disposed transversely of the length of the web, fluid inlet port forming means associated with the body member in fluid communication with the chamber, baffle means interposed in the path of fluid moving from the fluid inlet port forming means through the chamber and the fluid discharge orifice forming means to determine the direction of movement of fluid passing through the fluid dis-charge orifice forming means, the baffle means being shaped to impart to fluid impinging on the baffle means and moving through each end portion of the fluid discharge orifice forming means movement having a compon-ent parallel to the associated surface of the web and in a direction toward the associated marginal portion of the web to thereby move liquid coating on the associated marginal portion of the web outwardly and downwardly relative to the surface of the web.
33. The apparatus of claim 32 wherein the baffle means comprise at least in part vanes shaped to impart to the fluid impinging on the baffle means the movement having a component parallel to the associated surface of the web and in a direction toward the associated marginal portion of the web to thereby move liquid coating on the associated marginal portion of the web outwardly and downwardly relative to the surface of the web.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
34. Apparatus as claimed in claim 1, wherein said nozzles for impinging said stream of fluid against said web are non-coplanar.
35. Apparatus as claimed in claim 30 wherein said nozzles are off-set from each other relative to the length of said web in its direction of travel.
36. Apparatus as claimed in claim 30 or 31 wherein at least one of said nozzles directs a said stream of fluid at an angle of up to 15° to a plane perpendicular to a surface of said web.
37. A method as claimed in claim 29 wherein said stream impinges against said one surface of the web at an angle up to 15° to a plane perpendicular to said one surface.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US54059975A | 1975-01-13 | 1975-01-13 | |
| US540,599 | 1975-01-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1082912A true CA1082912A (en) | 1980-08-05 |
Family
ID=24156142
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA243,363A Expired CA1082912A (en) | 1975-01-13 | 1976-01-12 | Apparatus for liquid coating thickness control, fluid nozzle and method of removing excess liquid coating from web edges |
Country Status (11)
| Country | Link |
|---|---|
| BE (1) | BE837498A (en) |
| BR (1) | BR7600130A (en) |
| CA (1) | CA1082912A (en) |
| DE (1) | DE2600838A1 (en) |
| FR (1) | FR2297090A1 (en) |
| GB (1) | GB1531321A (en) |
| IT (1) | IT1052921B (en) |
| LU (1) | LU74158A1 (en) |
| NZ (1) | NZ179743A (en) |
| SE (1) | SE7600244L (en) |
| ZA (1) | ZA76189B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI105533B (en) * | 1992-10-26 | 2000-09-15 | Valmet Paper Machinery Inc | Spray Coating Apparatus and Method |
| CN100467140C (en) * | 2004-05-10 | 2009-03-11 | 鸿富锦精密工业（深圳）有限公司 | Coating equipment |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB764364A (en) * | 1955-02-04 | 1956-12-28 | United States Steel Corp | Method of controlling coating thickness in continuous galvanizing |
| US2894856A (en) * | 1956-08-31 | 1959-07-14 | Inland Steel Co | Apparatus for and method of controlling the coating thickness in continuous galvanizing |
| US3808033A (en) * | 1970-01-27 | 1974-04-30 | Nat Steel Corp | Continuous metallic strip hot-dip metal coating apparatus |
| GB1325235A (en) * | 1970-08-13 | 1973-08-01 | Lysaght Australia Ltd | Stripping excess coating liquid from moving strip material |
| US3756844A (en) * | 1971-07-30 | 1973-09-04 | Armco Steel Corp | Zed spangle produkt controlling cooling of galvanized strip in process of forming minimiz |
| FR2155790A1 (en) * | 1971-10-05 | 1973-05-25 | Heurtey Sa | Coating metal eg steel - with protective alloy eg zinc or aluminium coatings by dipping and spraying with hot gas |
| US3841557A (en) * | 1972-10-06 | 1974-10-15 | Nat Steel Corp | Coating thickness control and fluid handling |
-
1976
- 1976-01-12 SE SE7600244A patent/SE7600244L/en unknown
- 1976-01-12 BR BR7600130A patent/BR7600130A/en unknown
- 1976-01-12 BE BE163460A patent/BE837498A/en unknown
- 1976-01-12 DE DE19762600838 patent/DE2600838A1/en active Pending
- 1976-01-12 CA CA243,363A patent/CA1082912A/en not_active Expired
- 1976-01-12 NZ NZ179743A patent/NZ179743A/en unknown
- 1976-01-12 GB GB974/76A patent/GB1531321A/en not_active Expired
- 1976-01-12 IT IT47593/76A patent/IT1052921B/en active
- 1976-01-12 LU LU74158A patent/LU74158A1/xx unknown
- 1976-01-12 FR FR7600580A patent/FR2297090A1/en active Granted
- 1976-01-13 ZA ZA760189A patent/ZA76189B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE2600838A1 (en) | 1976-07-15 |
| LU74158A1 (en) | 1976-07-20 |
| NZ179743A (en) | 1979-01-11 |
| IT1052921B (en) | 1981-08-31 |
| BR7600130A (en) | 1976-08-31 |
| FR2297090A1 (en) | 1976-08-06 |
| SE7600244L (en) | 1976-07-14 |
| GB1531321A (en) | 1978-11-08 |
| ZA76189B (en) | 1977-06-29 |
| BE837498A (en) | 1976-05-03 |
| FR2297090B1 (en) | 1980-01-25 |
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| MKEX | Expiry |