CA1091994A - Removal of excess liquid coatant from strip - Google Patents
Removal of excess liquid coatant from stripInfo
- Publication number
- CA1091994A CA1091994A CA302,257A CA302257A CA1091994A CA 1091994 A CA1091994 A CA 1091994A CA 302257 A CA302257 A CA 302257A CA 1091994 A CA1091994 A CA 1091994A
- Authority
- CA
- Canada
- Prior art keywords
- baffle
- nozzle
- strip
- seal
- header
- 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
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Coating Apparatus (AREA)
- Coating With Molten Metal (AREA)
- Cleaning In General (AREA)
- Spray Control Apparatus (AREA)
- Cleaning By Liquid Or Steam (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Abstract
A B S T R A C T
A device is provided for removing excess liquid coatant, for example zinc, from a continuous strip for example, steel strip emerging from a bath containing the liquid, the device comprising a cylindrical header having a pair of lips defining an elongate nozzle having a slot for directing a fluid jet onto the strip surface, there being a pair of spaced part-cylindrical baffles nesting within the header and dimensioned to close off all but a portion of the nozzle from the header whereby axial rotation of the baffles varies the length of the open nozzle portion and thereby the length of the fluid jet transverse to the strip. In use, two such devices are disposed on opposite sides of the strip and any impingement of the opposed jets upon each other at or beyond the strip edges is detected by noise level detectors. The baffles can then be moved to minimise the degree of impingement and thereby reduce the noise level resulting from impingement.
A device is provided for removing excess liquid coatant, for example zinc, from a continuous strip for example, steel strip emerging from a bath containing the liquid, the device comprising a cylindrical header having a pair of lips defining an elongate nozzle having a slot for directing a fluid jet onto the strip surface, there being a pair of spaced part-cylindrical baffles nesting within the header and dimensioned to close off all but a portion of the nozzle from the header whereby axial rotation of the baffles varies the length of the open nozzle portion and thereby the length of the fluid jet transverse to the strip. In use, two such devices are disposed on opposite sides of the strip and any impingement of the opposed jets upon each other at or beyond the strip edges is detected by noise level detectors. The baffles can then be moved to minimise the degree of impingement and thereby reduce the noise level resulting from impingement.
Description
The present invent;on is concerned with improvements in the coating of strip and particularly with devices commonly known as fluid or gas knives which remove excess liquid coatant from a strip moving upwardly from a bath containing the coatant~
In the coating of strip9 particularly the galvanising of steel strip, the strip is introduced into a molten bath of the zinc to form the coating on the strip~ Generally the strip coated in this manner has an excessively thick and uneven coating of zinc. To remove the excess ~inc and provide a uniform zinc coating, it is the conventional practice to subject the strip, at a position just above the surface of the bath where the zinc is still molten, to the action of two jets of fluid, for example, air or steam on opposed surfaces of the strip transversely of the strip width. The air or steam jets issue from devices known conventionally as fluid or gas knives, which comprise elongate nozzles with a slot through which the jets of air or steam emerge. The jets form barriers kending to cause the excess æinc to run back towards the bath of molten zinc.
To ensure that the complete width of the strip is subjected to the action of the jets, the nozzle is normally ~ 3 ~
dimensioned to extend beyond either Longitudinal edge of the strip so that the fluid jet also extends beyond the edges. Unfortunately, th;s gives rise to a significant and usually unacceptable noise problem caused by the impingement upon each other of the opposed fluid jets at the regions beyond the edges of the strip.
It is therefore an object of the present invention to provide a device in which the degree of jet impingement is at least reduced so as to lower the noise level inherent in the use of these devices.
It is a further object of the present invention to provide a method and apparatus whereby the extent of jet impingement can be at least reduced by automatic control.
According to one aspect of the present invention, a device is provided for removing excess liguid coatant from a strip moving upwardly from a bath containing the liquid, the device comprising a cylindrical header having a pair of lips defining an elongate nozzle having a slot for directing a fluid jet onto the strip surface, together with at least one part-cylindrical side baffle nesting within the header and dimensioned to close off all but a portion of the nozzle from the header, the baffle being so shaped that axial rotation thereof varies the length of the open nozzle portion and thereby the length and alignment of the fluid jet transverse to the strip.
Preferably two baffles are provided7 one at each end of the header so that all but an intermediate portion of the nozzle is closed off from the header and each baffle is suitably provided with a portion having a circumferential edge following a helical path.
Suitably a movable side seal is provided for the or each baffle, the or each side seal being located within the space between the nozzle lips and the baffle, the or each seal being located adjacent the point or points where fluid from the baffle or baffles enters the nozzle and the or each seal being effective substantially lS to limit the length of the fluid jet issuing from the slot to that of the open nozzle portion.
Conveniently the or each baffle and the or each seal are motor driven, and preferably the or each seal and lts corresponding baffle are coupled together by gearing in such a manner that the linear vector of baffle movement and that of the seal are coincident.
According to a further aspect of the present invention9 a method is provided for removing excess liquid coatant from a strip moving upwardly from a bath containing the li~uid, the method comprising directing fluid jets upon opposite sides of the strip, sensing the impingement upon each other of the opposed jets at positions adjacerlt or beyond the edges of the strip, and, in response to sensed impingement, conrolling the length and alignment of each jet to reduce or avoid jet impingementO
Preferably jet impingement is sensed by sensing the noise level adjacent or beyond each strlp edge.
According to a still urther aspect of the present invention, apparatus is provided for removing excess liquid coatant from a strip moving upwardly from a bath containing the liquid, the apparatus comprising two elongate nozzles for location on opposite sides of the strip, the nozzles being defined by a pair of lips forming a slot for directing a fluid jet onto the strip surace, each nozzle having associated therewith at least one movable side shutter effective to vary the length of the jet, means for sensing the impingement of opposed jets adjacent or beyond each edge of the strip, together with means responsive to the impingement sensing means for moving the shutter to a ~ 9 ~
position where the jet length and alignment is such that jet impingement is reduced or avoided~
Preferably two movable side shutters are provided at each end of each nozzle and in this case the means for sensing the impingement of opposed jets comprises a pair of noise level detectors. Suitably the means for moving the shutters comprises a motor responsive to an output from the impingement sensing means.
Conveniently, each shutter is driven by its own motor.
Preferably the nozzle lips extend from a cylindrical header and in this case the shutter or each shutter in the header is a baffle nesting within the header and dimensioned to close off all but a portion of the nozzle from the header. The or each baffle in the header may be part-cylindrical and so shaped that axial rotation thereof varies the length of the open nozzle portion and thereby the length and alignment of the fluid jet transverse to the strip.
Suitably the baffles are provided with a portion having a circumferential edge following a helical path. In one embodiment of the invention, a movable side seal is provided for each baffle, the or each side seal being located within the space between the nozzle lips and the ffl~L
baffle, the or e~ch side seal being located adjacent the points where fluid from the or each baffle enters the nozzle and each seal being effective substantially to limit the length of the fluid jet issuing from the slot to that of the intermediate nozzle portion.
Preferably each seal and its corresponding baffle are motor-driven and are coupled together by gearing in such a manner that the linear vector of baffle movement and that of the seal are coinoident..
An embodiment of the invention will now be particularly described by way of example ~nly with reference to the accompanying drawings in which:-Figure 1 is a front view in elevation of a device in use during the galvanising coating of steel strip emerging from its coating bath;
Figure 2 is a side view in section along lines II - II
of Figure 1;
Figure 3 is a perspective view of a side baffle;
Figure 4 is a sectioned front view showing the coupling between a side baffle and its drive gear;
Figure 5 is a top view of an end section of two fluid devices at opposite sides of a steel strip9 and Figure 6 is a sectioned front view of a bottle~jack ~ 3 9 ~
for driving a baffle sealing memberO
Referring to Figure 1, the device sho~n generally at 1 comprises a cylindrical header 2 which is mounted by an elongate support bracket 3 above a bath 4 containing in this case molten zinc 5~ The device 1 also comprises a nozzle an assembly shown generally at 6 ~to be described more fully later) which is horizvntally disposed adjacent a steel strip 7 which emerges upwardly from the zinc 5 yia the rolls 62,63 the strip 7 thereby having a molten coating of zinc. The excess ~inc is stripped away by the action of an air jet issuing from the nozzle assembly 6 of the device 1. A similar device 10 is disposed on an opposite side of the strip 7 as shown in Figure 5 to strip excess molten zinc from that side of the strip 7.
Referring to Figure 2 9 the nozzle assembly 6 comprises a pair of upper and lower lips 8 and 9 which are angled towards each other and define at their strip-facing ends an elongate slot 11 through which a flat jet of air can issue onto the strip 7. Each lip 8, 9 is held at two positions by screws 12, 13 to plates 14, 15 which are welded to the circumference of the header 2. Within the header 2 nests at either end thereof part-cylindrical.
~ 9 ~
side bafles 16 (only one shown) which are rotatable to close off from the header 2 the nozzle lips 8, 9.
Triangular shaped seals 17 are located within the space defined by the lips 8, 9 and the baffles 16 adjacent the points where the air from the baffles 16 enters the nozzle assembly 6. The seals 17 have one concave wall 18 so as to mate with the adjacent baffle wall. The seals 17 like the baffles 16 are a close fit within the space they occupy.
Attached to the lower lip 9 is an elongate buffer means 19 comprising a plate 20 having welded to a front portion within a concave recess a circular steel rod 21 which extends beyond the front strip-facing edges of the lips 8, 9. The buffer means 19 prevents the strip 7 from contacting the edges of the lips 8, 9 should the strip 7 veer towards the lips 8, 9 during the coating process. In this way blockage of the slot 10 by solidified zinc is prevented.
Referring to Figure 3, the side baffle 16 has a wall 22 in cylindrical fonm which extends from a circumferentially flanged end 23 to a point someway along its length. At this point the baffle wall 22 is open and has a helical edge 24 tracing towards the flanged end 23 a clockwise path. The ends 25, 26 of the helix 24 are joined via an edge 27 parallel to the axis of the baffle 16.
As shown in Figure 3 and in Figure 4~ the flanged end 23 of the baffle 16 is toothed to enable the end 23 to mesh with a gear 28 (Figure 4) and so drive and axially rotate the baffle 16. The flanged end 23 and the gear 28 are located between flanged end portions 29, 30 of the header 2 and a detachable header portion 31 which is bolted to the header 2 via nut and bolt arrangement 32. The flanged end 23 of the baffle 16 is spaced from the flanged end portions 29, 30 by annular bearings 33, 34 while the cylindrical portion of the baffle wall 22 is provided with a sleeve bearing 35. Gear 28 is attached to a shaft 36 which rotates upon bearings 37, 38 disposed within apertures in the flanged end portions 29, 30.
Referring to Figure 5, drive for the shaft 36 is derived from a universal coupling 39 and a gear-box 40.
Drive for the gear-box 40 is supplied from an electric motor (not shown). The seal 17 is driven by a bottle-jack arrangemen`t 41 (to be described laterj, coupled via a shaft 42 J a universal coupling 43~ and the gear-box 40 directly to a motor-driven shaft 44~ The universal O g couplings 39 and 43 are each provided with interneshing gears (not shown) within the gear-box 40.
Referring to ~igure 6, the seal 17 comprises two steel plates 45 and 46 spaced from each other by a sealing gasket 47 which abuts the wall 22 of the baffle 16 and the nozzle lips (not shown). The seal 17 is attached to a shaft 48 which forms part of the bottle-jack 41. The bottle-jack 41 comprises a cylinder 49 which is secured to the header 2~ An internally threaded outer sleeve 50 is rotated by the shaft h2 with which the outer sleeve 50 is integral, the shaft 42 being driven by the universal coupling 43, The sleeve shoulders 51 and its ends 52 abut against the flanged ends 53, 54 of the cylinder 49 and the sleeve 50 is spaced from the internal walls of the cylinder 47 by sleeve bushes 55, 560 An inner sleeve 57 is partially threaded on its outer surface and engages with the outer sleeve 50. The inner sleeve 57 is also wholly internally threaded and is engaged with a threaded portion of the shaft 48~ Appropriate rotation of the outer sleeve 50 causes the inner sleeve 57 to rotate and move the inner sleeve forward past the flanged ends 53 and the end 58 of the nozzle 6. Since the shaft 48 is engaged with the inner sleeve 57, it too 9~4 moves forward thereby moving the seal 17 forward.
When the externally threaded portion of the inner sleeve 57 engages with the flange 53 of ~he cylinder 47, movement of the inner sleeve 57 is prevented and further forward movement is provided by the shaft 48 itself. Backward movement of course is exactly the reverse of the above process.
Referring against to Figure 5, axial rotation of the baffle 16 will cause the helical edge 24 to change its position linearly in direct proportion to the amount of angular rotation of the baffle 16. Consequently, by ~selecting a suitable gear ratio, the linear vector of baffle movement and that of its adjacent seal 17 can be made to coincide, In Figure 5 the baffle 16 has been rotated to a position where the header 2 has been cut off from the nozzle 6 at a point indicated by 59. Thus the flow of gas from the header 2 to the nozzle 6 is confined to that portion of the nozzle 6 lying inter-mediate point 59 and a distant point defined by the baffle (not shown) located at the other end of header 2.
Thus the length of the gas jet issuing through the slot 11 is substantially limited in length to that of the nozzle 6 intermediate point 59 and the distant point 9i~34 defined by the other baffle. Since in practice air is introduced at both ends of the header 2, air can still be deflected through the nozzle (and thereby its slot) at an outward lateral angle,. The seal 17, located adjacent the point where the air leàves the baffle 16, presents a barrier~to such deflected air and thereby limits the length of the air jet issuing from the slot 11 to that of the nozzle portion inter-mediate the baffles 16 located within each header 2.
The practice is of course identical in device 10.
Thus it will be appreciated that movement of the baffle 16 and its appropriate seal 17, can be varied to confine the position and length of the air jet to . the boundary limits defined by the edges of the strip which the nozzle faces. This reduces, or perhaps even eliminates, the ability of the opposed jets from the opposed devices 1 and 10 to impinge upon each other and thus reduces the noise level associated with such I devices.
Movement of the baffle 16 and its seal 17 can be automatically controlled as shown in Figure 5. A
decibel meter 60 ;s located adjacent the nozzles of the opposed devices 1, 10 just beyond a s~rip edge 61.
g~
A similar meter (not shown) is located just beyond the other strip edge (not shown).
A signal representative of the noise level reading from meter 60 is compared with a signal representative of a standard or desired noise level reading in a suitable error detector such as a control transformer (not shown). An error signal indicative of excessive noise is then fed back via an appropriate servo-amplifier (not shown) to the motors (not shown) controlling the drive of the baffles 16 and seals 17 in devices 1 and 10, so as to move the baffles 16 and seals 17 to a position ~here the impingement of the opposed nozzle jets is a minimum. As previously explained, this usually occurs when the length of the jet is confined between the boundary defined by the edges of the strip, i.e. the transverse width of the strip. i
In the coating of strip9 particularly the galvanising of steel strip, the strip is introduced into a molten bath of the zinc to form the coating on the strip~ Generally the strip coated in this manner has an excessively thick and uneven coating of zinc. To remove the excess ~inc and provide a uniform zinc coating, it is the conventional practice to subject the strip, at a position just above the surface of the bath where the zinc is still molten, to the action of two jets of fluid, for example, air or steam on opposed surfaces of the strip transversely of the strip width. The air or steam jets issue from devices known conventionally as fluid or gas knives, which comprise elongate nozzles with a slot through which the jets of air or steam emerge. The jets form barriers kending to cause the excess æinc to run back towards the bath of molten zinc.
To ensure that the complete width of the strip is subjected to the action of the jets, the nozzle is normally ~ 3 ~
dimensioned to extend beyond either Longitudinal edge of the strip so that the fluid jet also extends beyond the edges. Unfortunately, th;s gives rise to a significant and usually unacceptable noise problem caused by the impingement upon each other of the opposed fluid jets at the regions beyond the edges of the strip.
It is therefore an object of the present invention to provide a device in which the degree of jet impingement is at least reduced so as to lower the noise level inherent in the use of these devices.
It is a further object of the present invention to provide a method and apparatus whereby the extent of jet impingement can be at least reduced by automatic control.
According to one aspect of the present invention, a device is provided for removing excess liguid coatant from a strip moving upwardly from a bath containing the liquid, the device comprising a cylindrical header having a pair of lips defining an elongate nozzle having a slot for directing a fluid jet onto the strip surface, together with at least one part-cylindrical side baffle nesting within the header and dimensioned to close off all but a portion of the nozzle from the header, the baffle being so shaped that axial rotation thereof varies the length of the open nozzle portion and thereby the length and alignment of the fluid jet transverse to the strip.
Preferably two baffles are provided7 one at each end of the header so that all but an intermediate portion of the nozzle is closed off from the header and each baffle is suitably provided with a portion having a circumferential edge following a helical path.
Suitably a movable side seal is provided for the or each baffle, the or each side seal being located within the space between the nozzle lips and the baffle, the or each seal being located adjacent the point or points where fluid from the baffle or baffles enters the nozzle and the or each seal being effective substantially lS to limit the length of the fluid jet issuing from the slot to that of the open nozzle portion.
Conveniently the or each baffle and the or each seal are motor driven, and preferably the or each seal and lts corresponding baffle are coupled together by gearing in such a manner that the linear vector of baffle movement and that of the seal are coincident.
According to a further aspect of the present invention9 a method is provided for removing excess liquid coatant from a strip moving upwardly from a bath containing the li~uid, the method comprising directing fluid jets upon opposite sides of the strip, sensing the impingement upon each other of the opposed jets at positions adjacerlt or beyond the edges of the strip, and, in response to sensed impingement, conrolling the length and alignment of each jet to reduce or avoid jet impingementO
Preferably jet impingement is sensed by sensing the noise level adjacent or beyond each strlp edge.
According to a still urther aspect of the present invention, apparatus is provided for removing excess liquid coatant from a strip moving upwardly from a bath containing the liquid, the apparatus comprising two elongate nozzles for location on opposite sides of the strip, the nozzles being defined by a pair of lips forming a slot for directing a fluid jet onto the strip surace, each nozzle having associated therewith at least one movable side shutter effective to vary the length of the jet, means for sensing the impingement of opposed jets adjacent or beyond each edge of the strip, together with means responsive to the impingement sensing means for moving the shutter to a ~ 9 ~
position where the jet length and alignment is such that jet impingement is reduced or avoided~
Preferably two movable side shutters are provided at each end of each nozzle and in this case the means for sensing the impingement of opposed jets comprises a pair of noise level detectors. Suitably the means for moving the shutters comprises a motor responsive to an output from the impingement sensing means.
Conveniently, each shutter is driven by its own motor.
Preferably the nozzle lips extend from a cylindrical header and in this case the shutter or each shutter in the header is a baffle nesting within the header and dimensioned to close off all but a portion of the nozzle from the header. The or each baffle in the header may be part-cylindrical and so shaped that axial rotation thereof varies the length of the open nozzle portion and thereby the length and alignment of the fluid jet transverse to the strip.
Suitably the baffles are provided with a portion having a circumferential edge following a helical path. In one embodiment of the invention, a movable side seal is provided for each baffle, the or each side seal being located within the space between the nozzle lips and the ffl~L
baffle, the or e~ch side seal being located adjacent the points where fluid from the or each baffle enters the nozzle and each seal being effective substantially to limit the length of the fluid jet issuing from the slot to that of the intermediate nozzle portion.
Preferably each seal and its corresponding baffle are motor-driven and are coupled together by gearing in such a manner that the linear vector of baffle movement and that of the seal are coinoident..
An embodiment of the invention will now be particularly described by way of example ~nly with reference to the accompanying drawings in which:-Figure 1 is a front view in elevation of a device in use during the galvanising coating of steel strip emerging from its coating bath;
Figure 2 is a side view in section along lines II - II
of Figure 1;
Figure 3 is a perspective view of a side baffle;
Figure 4 is a sectioned front view showing the coupling between a side baffle and its drive gear;
Figure 5 is a top view of an end section of two fluid devices at opposite sides of a steel strip9 and Figure 6 is a sectioned front view of a bottle~jack ~ 3 9 ~
for driving a baffle sealing memberO
Referring to Figure 1, the device sho~n generally at 1 comprises a cylindrical header 2 which is mounted by an elongate support bracket 3 above a bath 4 containing in this case molten zinc 5~ The device 1 also comprises a nozzle an assembly shown generally at 6 ~to be described more fully later) which is horizvntally disposed adjacent a steel strip 7 which emerges upwardly from the zinc 5 yia the rolls 62,63 the strip 7 thereby having a molten coating of zinc. The excess ~inc is stripped away by the action of an air jet issuing from the nozzle assembly 6 of the device 1. A similar device 10 is disposed on an opposite side of the strip 7 as shown in Figure 5 to strip excess molten zinc from that side of the strip 7.
Referring to Figure 2 9 the nozzle assembly 6 comprises a pair of upper and lower lips 8 and 9 which are angled towards each other and define at their strip-facing ends an elongate slot 11 through which a flat jet of air can issue onto the strip 7. Each lip 8, 9 is held at two positions by screws 12, 13 to plates 14, 15 which are welded to the circumference of the header 2. Within the header 2 nests at either end thereof part-cylindrical.
~ 9 ~
side bafles 16 (only one shown) which are rotatable to close off from the header 2 the nozzle lips 8, 9.
Triangular shaped seals 17 are located within the space defined by the lips 8, 9 and the baffles 16 adjacent the points where the air from the baffles 16 enters the nozzle assembly 6. The seals 17 have one concave wall 18 so as to mate with the adjacent baffle wall. The seals 17 like the baffles 16 are a close fit within the space they occupy.
Attached to the lower lip 9 is an elongate buffer means 19 comprising a plate 20 having welded to a front portion within a concave recess a circular steel rod 21 which extends beyond the front strip-facing edges of the lips 8, 9. The buffer means 19 prevents the strip 7 from contacting the edges of the lips 8, 9 should the strip 7 veer towards the lips 8, 9 during the coating process. In this way blockage of the slot 10 by solidified zinc is prevented.
Referring to Figure 3, the side baffle 16 has a wall 22 in cylindrical fonm which extends from a circumferentially flanged end 23 to a point someway along its length. At this point the baffle wall 22 is open and has a helical edge 24 tracing towards the flanged end 23 a clockwise path. The ends 25, 26 of the helix 24 are joined via an edge 27 parallel to the axis of the baffle 16.
As shown in Figure 3 and in Figure 4~ the flanged end 23 of the baffle 16 is toothed to enable the end 23 to mesh with a gear 28 (Figure 4) and so drive and axially rotate the baffle 16. The flanged end 23 and the gear 28 are located between flanged end portions 29, 30 of the header 2 and a detachable header portion 31 which is bolted to the header 2 via nut and bolt arrangement 32. The flanged end 23 of the baffle 16 is spaced from the flanged end portions 29, 30 by annular bearings 33, 34 while the cylindrical portion of the baffle wall 22 is provided with a sleeve bearing 35. Gear 28 is attached to a shaft 36 which rotates upon bearings 37, 38 disposed within apertures in the flanged end portions 29, 30.
Referring to Figure 5, drive for the shaft 36 is derived from a universal coupling 39 and a gear-box 40.
Drive for the gear-box 40 is supplied from an electric motor (not shown). The seal 17 is driven by a bottle-jack arrangemen`t 41 (to be described laterj, coupled via a shaft 42 J a universal coupling 43~ and the gear-box 40 directly to a motor-driven shaft 44~ The universal O g couplings 39 and 43 are each provided with interneshing gears (not shown) within the gear-box 40.
Referring to ~igure 6, the seal 17 comprises two steel plates 45 and 46 spaced from each other by a sealing gasket 47 which abuts the wall 22 of the baffle 16 and the nozzle lips (not shown). The seal 17 is attached to a shaft 48 which forms part of the bottle-jack 41. The bottle-jack 41 comprises a cylinder 49 which is secured to the header 2~ An internally threaded outer sleeve 50 is rotated by the shaft h2 with which the outer sleeve 50 is integral, the shaft 42 being driven by the universal coupling 43, The sleeve shoulders 51 and its ends 52 abut against the flanged ends 53, 54 of the cylinder 49 and the sleeve 50 is spaced from the internal walls of the cylinder 47 by sleeve bushes 55, 560 An inner sleeve 57 is partially threaded on its outer surface and engages with the outer sleeve 50. The inner sleeve 57 is also wholly internally threaded and is engaged with a threaded portion of the shaft 48~ Appropriate rotation of the outer sleeve 50 causes the inner sleeve 57 to rotate and move the inner sleeve forward past the flanged ends 53 and the end 58 of the nozzle 6. Since the shaft 48 is engaged with the inner sleeve 57, it too 9~4 moves forward thereby moving the seal 17 forward.
When the externally threaded portion of the inner sleeve 57 engages with the flange 53 of ~he cylinder 47, movement of the inner sleeve 57 is prevented and further forward movement is provided by the shaft 48 itself. Backward movement of course is exactly the reverse of the above process.
Referring against to Figure 5, axial rotation of the baffle 16 will cause the helical edge 24 to change its position linearly in direct proportion to the amount of angular rotation of the baffle 16. Consequently, by ~selecting a suitable gear ratio, the linear vector of baffle movement and that of its adjacent seal 17 can be made to coincide, In Figure 5 the baffle 16 has been rotated to a position where the header 2 has been cut off from the nozzle 6 at a point indicated by 59. Thus the flow of gas from the header 2 to the nozzle 6 is confined to that portion of the nozzle 6 lying inter-mediate point 59 and a distant point defined by the baffle (not shown) located at the other end of header 2.
Thus the length of the gas jet issuing through the slot 11 is substantially limited in length to that of the nozzle 6 intermediate point 59 and the distant point 9i~34 defined by the other baffle. Since in practice air is introduced at both ends of the header 2, air can still be deflected through the nozzle (and thereby its slot) at an outward lateral angle,. The seal 17, located adjacent the point where the air leàves the baffle 16, presents a barrier~to such deflected air and thereby limits the length of the air jet issuing from the slot 11 to that of the nozzle portion inter-mediate the baffles 16 located within each header 2.
The practice is of course identical in device 10.
Thus it will be appreciated that movement of the baffle 16 and its appropriate seal 17, can be varied to confine the position and length of the air jet to . the boundary limits defined by the edges of the strip which the nozzle faces. This reduces, or perhaps even eliminates, the ability of the opposed jets from the opposed devices 1 and 10 to impinge upon each other and thus reduces the noise level associated with such I devices.
Movement of the baffle 16 and its seal 17 can be automatically controlled as shown in Figure 5. A
decibel meter 60 ;s located adjacent the nozzles of the opposed devices 1, 10 just beyond a s~rip edge 61.
g~
A similar meter (not shown) is located just beyond the other strip edge (not shown).
A signal representative of the noise level reading from meter 60 is compared with a signal representative of a standard or desired noise level reading in a suitable error detector such as a control transformer (not shown). An error signal indicative of excessive noise is then fed back via an appropriate servo-amplifier (not shown) to the motors (not shown) controlling the drive of the baffles 16 and seals 17 in devices 1 and 10, so as to move the baffles 16 and seals 17 to a position ~here the impingement of the opposed nozzle jets is a minimum. As previously explained, this usually occurs when the length of the jet is confined between the boundary defined by the edges of the strip, i.e. the transverse width of the strip. i
Claims (28)
1. A device for removing excess liquid coatant from a continuous strip emerging from a bath containing the liquid, the device comprising a cylindrical header having a pair of lips defining an elongate nozzle having a slot for directing a fluid jet onto the strip surface, together with at least one part-cylindrical baffle nesting within the header and dimensioned to close off all but a portion of the nozzle from the header, the baffle being so shaped that axial rotation thereof varies the length of the open nozzle portion and thereby the length of the fluid jet transverse to the strip.
2. A device according to claim 1 in which two baffles are provided, one at each end of the header so that all but an intermediate portion of the nozzle is closed off from the header.
3. A device according to claim 1 in which the or each baffle is provided with a portion having a circumferential edge following a helical path.
4. A device according to claim 2 in which the or each baffle is provided with a portion having a circumferential edge following a helical path.
5. A device according to claim 1 in which a movable side seal is provided for the or each baffle, the or each side seal being located within the space between the nozzle lips and the baffle, the or each seal being located adjacent the point or points where fluid from the baffle or baffles enters the nozzle and the or each seal being effective substantially to limit the length of the fluid jet issuing from the slot to that of the open nozzle portion.
6. A device according to claim 2 in which a movable side seal is provided for each baffle, each side seal being located within the space between the nozzle lips and the baffle, each seal being located adjacent the point or points where fluid from the baffles enters the nozzle and each seal being effective substantially to limit the length of the fluid jet issuing from the slot to that of the open nozzle portion.
7. A device according to claim 1 in which the or each baffle is motor driven.
8. A device according to claim 2 in which each baffle is motor driven.
9. A device according to claim 5 in which the or each seal is motor driven.
10. A device according to claim 6 in which each seal is motor driven.
11. A device according to claim 9 or claim 10 in which the or each seal and its corresponding baffle are coupled together by gearing in such a manner that the linear vector of baffle movement and that of the seal are coincident.
12. A method for removing excess liquid coatant from a continuous strip emerging from a bath containing the liquid, the method comprising directing fluid jets upon opposite sides of the strip, sensing the impingement upon each other of the opposed jets at positions adjacent or beyond the edges of the strip, and, in response to sensed impingement, controlling the length of each jet to reduce or avoid jet impingement.
130 A method according to claim 12 in which jet impingement is sensed by sensing the noise level adjacent or beyond each strip edge.
14. Apparatus for removing excess liquid coatant from a continuous strip emerging from a bath containing the liquid, the apparatus comprising two elongate nozzles for location on opposite sides of the strip, the nozzles being defined by a pair of lips forming a slot for directing a fluid jet onto the strip surface, each nozzle having associated therewith at least one movable shutter effective to vary the length of the jet, means for sensing the impingement of opposed jets adjacent or beyond each edge of the strip, together with means responsive to the impingement sensing means for moving the or each shutter to a position where the jet length is such that jet impingement is reduced or avoided.
15. Apparatus according to claim 14 in which two movable side shutters are provided at each end of each nozzle.
16. Apparatus according to claim 14 in which the means for sensing the impingement of opposed jets comprises a noise level detector means.
17. Apparatus according to claim 15 in which the means for sensing the impingement of opposed jets comprises a pair of noise level detectors.
18. Apparatus according to claim 14 in which the means for moving each shutter comprises a motor responsive to an output from the impingement sensing means.
19, Apparatus according to claim 15 in which the means for moving each shutter comprises a motor responsive to an output from the impingement sensing means.
20. Apparatus according to claim 18 in which each shutter is driven by its own motor.
21. Apparatus according to claim 19 in which each shutter is driven by its own motor.
22. Apparatus according to claim 14 in which the nozzle lips extend from a cylindrical header, the shutter or each shutter in the header comprising a baffle nesting within the header and dimensioned to close off all but a portion of the nozzle from the header.
23. Apparatus according to claim 22 in which the or each baffle in the header is part cylindrical and is so shaped that axial rotation thereof varies the length of the open nozzle portion and thereby the length and alignment of the liquid jet transverse to the strip.
24. Apparatus according to claim 23 in which each baffle is provided with a portion having a circumferential edge following a helical path.
25. Apparatus according to claim 22 in which a movable side seal is provided for the or each baffle, the or each side seal being located within the space between the nozzle lips and the baffle, the or each side seal being located adjacent the points where fluid from the or each baffle enters the nozzle and each seal being effective substantially to limit the length of the fluid jet issuing from the slot to that of the open nozzle portion.
26. Apparatus according to claim 22 in which each baffle is motor driven.
27. Apparatus according to claim 25 in which each seal is motor driven.
28. Apparatus according to claim 27 in which each seal and its corresponding baffle are coupled together by gearing in such a manner that the linear vector of baffle movement and that of the seal are coincident.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB18013/77 | 1977-04-29 | ||
| GB18013/77A GB1602731A (en) | 1977-04-29 | 1977-04-29 | Removal of excess liquid coatant from skip |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1091994A true CA1091994A (en) | 1980-12-23 |
Family
ID=10105144
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA302,257A Expired CA1091994A (en) | 1977-04-29 | 1978-04-28 | Removal of excess liquid coatant from strip |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS549122A (en) |
| BE (1) | BE866501A (en) |
| BR (1) | BR7802685A (en) |
| CA (1) | CA1091994A (en) |
| DE (1) | DE2818620A1 (en) |
| ES (2) | ES469210A1 (en) |
| FI (1) | FI781304A (en) |
| FR (1) | FR2388605A1 (en) |
| GB (1) | GB1602731A (en) |
| IT (1) | IT7867976A0 (en) |
| LU (1) | LU79566A1 (en) |
| NL (1) | NL7804630A (en) |
| NO (1) | NO781500L (en) |
| SE (1) | SE7804918L (en) |
| ZA (1) | ZA782226B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61207790A (en) * | 1985-03-13 | 1986-09-16 | 清水建設株式会社 | Excavation of geothermal production well |
| DE19834759C2 (en) * | 1998-08-01 | 2002-02-21 | Salzgitter Ag | Method and device for removing dendrites |
| WO2010130884A1 (en) * | 2009-05-14 | 2010-11-18 | Arcelormittal Investigacion Y Desarrollo Sl | Method for producing a coated metal band having an improved appearance |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1005507B (en) * | 1972-11-27 | 1976-09-30 | Italsider Spa | PERFECTED DEVICE FOR CONTINUOUS REGULATION OF THE ZINC COATING OF A STEEL SHEET OR SIMILAR |
| IT1023842B (en) * | 1974-08-08 | 1978-05-30 | Italsider Spa | PERFECTED DEVICE FOR BLOWING A BLADE OF AIR AGAINST A TAPE COATED WITH A LAYER OF LIQUID MATERIAL, IN PARTICULAR AGAINST A METALLIC TAPE COVERED WITH A LAYER OF MELTED ZICO |
-
1977
- 1977-04-29 GB GB18013/77A patent/GB1602731A/en not_active Expired
-
1978
- 1978-04-19 ZA ZA00782226A patent/ZA782226B/en unknown
- 1978-04-26 FI FI781304A patent/FI781304A/en not_active Application Discontinuation
- 1978-04-27 BE BE187219A patent/BE866501A/en not_active IP Right Cessation
- 1978-04-27 NO NO781500A patent/NO781500L/en unknown
- 1978-04-27 DE DE19782818620 patent/DE2818620A1/en not_active Withdrawn
- 1978-04-27 ES ES469210A patent/ES469210A1/en not_active Expired
- 1978-04-28 IT IT7867976A patent/IT7867976A0/en unknown
- 1978-04-28 BR BR7802685A patent/BR7802685A/en unknown
- 1978-04-28 SE SE7804918A patent/SE7804918L/en unknown
- 1978-04-28 FR FR7812762A patent/FR2388605A1/en active Pending
- 1978-04-28 LU LU79566A patent/LU79566A1/en unknown
- 1978-04-28 CA CA302,257A patent/CA1091994A/en not_active Expired
- 1978-04-28 NL NL7804630A patent/NL7804630A/en not_active Application Discontinuation
- 1978-05-01 JP JP5262978A patent/JPS549122A/en active Pending
- 1978-12-14 ES ES475992A patent/ES475992A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| ES469210A1 (en) | 1979-10-01 |
| BE866501A (en) | 1978-08-14 |
| GB1602731A (en) | 1981-11-18 |
| ES475992A1 (en) | 1979-07-16 |
| FR2388605A1 (en) | 1978-11-24 |
| DE2818620A1 (en) | 1978-11-02 |
| JPS549122A (en) | 1979-01-23 |
| FI781304A (en) | 1978-10-30 |
| LU79566A1 (en) | 1978-11-03 |
| IT7867976A0 (en) | 1978-04-28 |
| ZA782226B (en) | 1979-04-25 |
| SE7804918L (en) | 1978-10-30 |
| BR7802685A (en) | 1978-11-14 |
| NO781500L (en) | 1978-10-31 |
| NL7804630A (en) | 1978-10-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |