CA1126593A - Coating of metal strip on one side with molten metal - Google Patents
Coating of metal strip on one side with molten metalInfo
- Publication number
- CA1126593A CA1126593A CA326,614A CA326614A CA1126593A CA 1126593 A CA1126593 A CA 1126593A CA 326614 A CA326614 A CA 326614A CA 1126593 A CA1126593 A CA 1126593A
- Authority
- CA
- Canada
- Prior art keywords
- strip
- metal
- molten metal
- zinc
- molten
- 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
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
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 With Molten Metal (AREA)
Abstract
ABSTRACT
Metal strip such as steel is coated on one side with molten metal such as zinc by passing the strip through a hood above a bath of molten metal. A scoop roller is partially immersed in the bath and cooperates with a supporting roller to define a nip through which the strip is continuously fed. The surface of the strip is coated by molten metal carried from the bath on the scoop roller.
Metal strip such as steel is coated on one side with molten metal such as zinc by passing the strip through a hood above a bath of molten metal. A scoop roller is partially immersed in the bath and cooperates with a supporting roller to define a nip through which the strip is continuously fed. The surface of the strip is coated by molten metal carried from the bath on the scoop roller.
Description
The invention relates to coating of metal strip on one side with a molten metal, in particular but not exclusively for hot galvanizing steel strip material.
For some years specialists have been endeavouring to develop suît-able processes and devices for coating a metal strip on one side with molten metal. The aim of these attempts is to obtain an even and precisely adjust-able layer thickness. Subsequently, a process is required in which molten metal does not reach the rear side of the strip during coating.
In a known process of this type the metal strip is conveyed in close proximity with the level of the melting bath, for example, by means of a supporting and deflection roller. Due to the surface tension of the molten metal, a meniscus of the molten metal between the surface of the bath and the metal strip once formed is maintained due to the short distance between metal strip and bath surface. In this way the moving strip is con-tinuously wetted by the molten metal. Control of the thickness of the coat-ing layer is achieved by stripping excess metal while still liquid by means of a connected jet knife (German Offenlegungsschrift 2,712,003). ~low-ever, the required layer thicknesses are only obtained with this adjustment means when the preceding layer applied is even over the entire width of the strip. Even coating over the entire width of the strip can only be achieved when the distance between the level of the bath and the strip does not fluc-tuate. This requirement is difficult to achieve with a very short set dis-tance, e.g.~ 10 mm. When the distance between the strip material and the level of the bath fluctuates, e.g. due to changes in the level of the bath, partial or complete breakup of the meniscus can result, or the molten metal can flow over the edges or the strip thus causing undesired coating of the rear side of the strip. There are several causes of fluctuations in the level of the bath: consumption of the molten metal by the coating process, 6~i93 refilling of the molten metal, blasting of the bath surface by the blast ~et of the nozzle stripper. All these difficulties can hardly be eliminated even with precise guidance of the strip and the use of a regulation plant to con-trol the level of the melting bath.
In another known process the strip to be coated is deflected by two deflection rollers by 90 in each case and conveyed by them approximately parallel to the level of the melting bath at a considerable distance therefrom.
The coating material is applied by means of a scoop roller immersed in the melt-ing bath onto the strip in the unsupported area between the two deflection rollers. The desired thickness of layer is set by means of a squeeze-off roll running on the scoop roller (United States patent 3,228,788).
It is indeed possible with this process and device to coat the strip on one side on its entire width without there being any danger of molten metal reaching the other side of the strip, but adjustability of the thickness of layer is not exact enough in spite of the additional squeeze-off roll. Even slight uneveness in the strip or movement of the strip radially of the scoop roller (shimmying) results in irregular contact of the strip and the scoop roller and thus in uneven coating.
The object of the invention is to provide a process and apparatus for coating a metal strip with molten metal which can achieve even coating of the metal strip on one side and exact adjustability within wide ranges.
The invention provides a process for coating one side of a metal strip with a molten metal from a melting bath, comprising the steps of continuously conveying a previously cleaned and heated metal strip through a protective gas atmosphere partially around a supporting roller and above the level of the melting bath of the molten metal for bringing the metal strip into contact with the molten metal, supporting the metal strip on a rear or reverse side thereof on the
For some years specialists have been endeavouring to develop suît-able processes and devices for coating a metal strip on one side with molten metal. The aim of these attempts is to obtain an even and precisely adjust-able layer thickness. Subsequently, a process is required in which molten metal does not reach the rear side of the strip during coating.
In a known process of this type the metal strip is conveyed in close proximity with the level of the melting bath, for example, by means of a supporting and deflection roller. Due to the surface tension of the molten metal, a meniscus of the molten metal between the surface of the bath and the metal strip once formed is maintained due to the short distance between metal strip and bath surface. In this way the moving strip is con-tinuously wetted by the molten metal. Control of the thickness of the coat-ing layer is achieved by stripping excess metal while still liquid by means of a connected jet knife (German Offenlegungsschrift 2,712,003). ~low-ever, the required layer thicknesses are only obtained with this adjustment means when the preceding layer applied is even over the entire width of the strip. Even coating over the entire width of the strip can only be achieved when the distance between the level of the bath and the strip does not fluc-tuate. This requirement is difficult to achieve with a very short set dis-tance, e.g.~ 10 mm. When the distance between the strip material and the level of the bath fluctuates, e.g. due to changes in the level of the bath, partial or complete breakup of the meniscus can result, or the molten metal can flow over the edges or the strip thus causing undesired coating of the rear side of the strip. There are several causes of fluctuations in the level of the bath: consumption of the molten metal by the coating process, 6~i93 refilling of the molten metal, blasting of the bath surface by the blast ~et of the nozzle stripper. All these difficulties can hardly be eliminated even with precise guidance of the strip and the use of a regulation plant to con-trol the level of the melting bath.
In another known process the strip to be coated is deflected by two deflection rollers by 90 in each case and conveyed by them approximately parallel to the level of the melting bath at a considerable distance therefrom.
The coating material is applied by means of a scoop roller immersed in the melt-ing bath onto the strip in the unsupported area between the two deflection rollers. The desired thickness of layer is set by means of a squeeze-off roll running on the scoop roller (United States patent 3,228,788).
It is indeed possible with this process and device to coat the strip on one side on its entire width without there being any danger of molten metal reaching the other side of the strip, but adjustability of the thickness of layer is not exact enough in spite of the additional squeeze-off roll. Even slight uneveness in the strip or movement of the strip radially of the scoop roller (shimmying) results in irregular contact of the strip and the scoop roller and thus in uneven coating.
The object of the invention is to provide a process and apparatus for coating a metal strip with molten metal which can achieve even coating of the metal strip on one side and exact adjustability within wide ranges.
The invention provides a process for coating one side of a metal strip with a molten metal from a melting bath, comprising the steps of continuously conveying a previously cleaned and heated metal strip through a protective gas atmosphere partially around a supporting roller and above the level of the melting bath of the molten metal for bringing the metal strip into contact with the molten metal, supporting the metal strip on a rear or reverse side thereof on the
- 2 -~, ...................................................................... .
supporting roller in the area of contact with the molten metal, and conveying the molten metal from the melting bath towards the supported area of the strip with a scoop roller immersed in the melting bath by more than half its surface area but only by part, which scoop roller together with the supporting roller forms an adjustable slot for the passage therebetween of the metal strip.
Exact geometric relationships are produced at the point of coating, where the strip maintains its position and shape and the coating material is conveyed in sufficient supply to the same point essentially independently of fluctuations in the level of the bath. Although no additional means is pro-vided for stripping off the excess molten metal, a precisely adjustable layer thickness can be obtained even when the molten metal is conveyed in excess, since the metal strip squeezes off excess material due to the forced guidance of the molten metal. The layer thickness can be set exactly within wide limits depending on the forced guidance of the molten metal due to the scoop roller and the support of the metal strip, and this is not only the case where large amounts are to be applied, but due to the continuing good contact between the surface of the strip and the scoop roller is the case even with small amounts to be applied. The thickness of layer can be set by adjusting the pressure between the scoop roller and the support roller.
The process according to the invention is particularly suitable for producing so-called galvanealed material (steel strip material, in which the molten zinc forms an alloy with the strip material), when according to ~.
~ - 3 -~265'33 one arrangement using zinc as the molten metal and steel as the strip mate-rial, the molten metal has a temperature of 450C to 480C and the strip temperature is from 530C to 650C, in particular 570, and quantity of molten zinc applied is restricted during application to the amount necessary for an alloy with the strip material. In addition, the danger of overflowing the edges of the strip is avoided by maintaining these ranges in temperature and thereby also maintaining a specific range of viscosity of the molten metal.
In this process the increase in temperature of the coating material necessary for the formation of the alloy is achieved by the heat of the strip material. ~his is directly possible with the necessary low amounts of coat-ing material to be applied. An advantage over known processes is that the molten coating material does not need any ceramic container~ due to its low temperature. Since the strip material is not directed through the melting bath but comes into contact with the melting bath only indirectly, and since the low application amount of molten coating material scooped is practically completely applied, i.e. no excess passes back into the melting bath, the melting bath is practically not heated further. Neither is an additional serially connected furnace needed, as was the case previously, to heat the costed strip material to the temperature necessary for formation of the alloy.
The strip materia] reaches the necessary temperature with the necessary annealing prior to the coating procedure. Then cooling is less intense than previously. With æinc as the coating material and steel as the strip mate-rlal, temperatures of 450 C to 480 C have proved favourab]e for the melting bath and 530C to 650 C for the strip material.
Preferably the scoop roller is immersed in the melting bath over more than half of its periphery. It is possible with this embodiment to convey lar~er application amounts into the nip without the scoop roller _ ~ _ ` ~Z6593 having its o~m drive means, since the liquid metal adhering to the scoop rol-ler exerts considerably lower restoring moments on the scoop roller than with a scoop roller which is only slightly immersed in the bath. Furthermore, in the case of a scoop roller which is more than half immersed in the bath there is less tendency for molten metal to flow back into the bath than in the case of a scoop roller which is only slightly im~ersed.
It has been found that with a scoop roller which is immersed too deeply in the bath there is danger of the molten metal flowing over the edges of the strip. In order to both eliminate this danger and apply the molten metal optimumly the scoop roller should pro~ect 10 to 45 mm, in particular 10 to 15 mm, out of the melting bath.
Preferably the diameter of the supporting and deflection roller should be ~ubstantially larger than the diameter of the scoop roller, in particular about double the size thereof. It is here advantageous when the diameter of the scoop roller is relatively small, in particular 150 to 350 mm, preferably about 250 mm.
Both the supporting and deflection roller and the scoop roller can be mounted to be freely rotatable. In this case, they are rotated by the strip running between them. In order to eliminate the danger of the roller coming to a standstill, the strip can be directed round the supporting and de~lection roller over a large angle of contact.
If a particularly thick layer is required, not only is a cor-respondingly wide passage slot or nip set between the scoop roller and the cupporting and deflection roller, but also the scoop roller is immersed to a correcponding depth in the melting bath. It can be of advantage here if the surface of the scoop roiler also has a high bonding strength for the molten metal due to roughening or suchlike. Further, the supply of the molten metal into the nip can be influenced by the speed of the surface of i, .. . .
- ~ :
~,~6593 the scoop roller being altered by means oP a drive means. If the speed of the surface of the scoop roller is greater than that of the strip, more molten metal is conveyed into the nip, if the speed of the surface of the scoop roller, however, is less than that of the strip, less molten metal is conveyed into the nip.
A preferred embodiment of the invention is explained in more detail below by means Or the drawing which represents the embodiment schematically.
; A container 1 is filled with molten metal 2, e.g. zinc. A cover-ing hood 3, which is open at the bottom, is immersed in the melting bath 2 at its lower edge. An inclined channel 4 and a vertical channel 5 lead into said covering hood 3. The channel 4 has a sluice-type inlet 6 and the chan-nel 5 has a sluice-type outlet 7.
A supporting and deflection roller 8 is freely rotatable above the level of the melting bath 2 and at a short distance therefrom. A scoop roller 9, which is substantially smaller in dia~eter than the supporting and deflection roller 8, is arranged below the latter, the axis of the scoop roller 9 being arranged parallel to the axis of the supporting and deflection roller 8 and in the same vertical plane. The scoop roller 9 is immersed in the melting bath 2 by more than half its surface area. The scoop roller 9 can be freely ~ournaled or actuated by an ad~ustable drive means.
The cleaned and heated strip material 12 to be coated runs over the aluice-type inlet 6, the channel 4 into the area of the covering hold 3 which is under an atmo8phere of protective gas. Here it is deflected by the sup-porting and deflection roller 8 and passed vertically upwards through chan-nel 5 and the sluice-type outlet 7. The strip material 12 loops the sup-porting and deflection roller 8 over an angle of about 135C. Thereby, exact guidance is achieved at only a short distance from the level of the bath.
:, .
'` ' ~26593 The scoop roller 9, which touches the surface of the strip material 12, transports molten metal into the nip 10 when the strip moves. The molten metal is applied with the desired thickness dependine on the selected dis-tance set between the two rollers 8,9. Excess metal is thereby squeezed off and flows back into the melting bath 2. Contrary to the known process of the German Offenlegungsschrift 2 712 003, however, the applied layer here can be set exactly independent of fluctuations in the level of the bath, as the molten metal is conveyed by the scoop roller to the surface of the strip which iB fixed in position and thus constant relationships are ensured. The setting of the thickness of layer is also more exact than is the case with the other known process of the United States patent 3 228 788, as contrary thereto the application amount here is not metered before the area of application but at the area of application itself. This means that in the process according to the invention high quality strip material can be pro-duced with different layer thicknesses while maintaining very close tol-erances. Maintaining close tolerances is not only of advantage for further processing but also means that considerable amounts of coating material are saved.
Although the layer thickness can be set exactly with a low cost in apparatus in the process according to the invention, ad~ustable nozzle strippers known per se can be additionally provided. Such nozzle strippers can be set at a height above the level of the melting bath, at a distance from the surface Or the bath and at the angle at which the gas jet is blown onto the bath. It has proved particularly advantageous to arrange the ~tripping nozzles at a height of lOO to 250 mm, in particular of about 150 mm, above the level of the melting bath. Since coating is carried out under an atmosphere of protective gas, it is, of course, necessary to also operate the nozzle strippers with a corresponding protective gas, e.g. nitrogen or .
'. ' , ' ' : .- :
1~65~
argon.
Zinc coatings on a steel strip often show large areas of crystal patterns (flowers of zinc), which are particularly undesirable when the galvanized surface of the strip is placed on the visible side of a structural part. This flower formation can be prevented very simply and effectively by blowing a nucleus forming agent, e.g. zinc or zinc oxide dust, onto the zinc layer when still liquid together with the gas jet of the stripping nozzles in accordance with a preferred feature of the invention.
The molten zinc in the melting bath is covered by a floating layer (not shown) of a substance which is insoluble in and/or not wettable by the molten zinc. This floating layer prevents or minimizes evaporation of the molten zinc, and may be particulate in nature, for example comprising a single layer or several layers of graphite balls. The effect of this layer is to improve the quality of the product. If eva~oration of the zinc is not ~revented. zinc vapor tends to condense within the covering hood 3 above the melting bath, and may drop as zinc dust onto the metal strip being processed, so that the reverse surface of the strip, or the strip before it is coated becomes dirty, thus necessitating an additional cleaning operation.
supporting roller in the area of contact with the molten metal, and conveying the molten metal from the melting bath towards the supported area of the strip with a scoop roller immersed in the melting bath by more than half its surface area but only by part, which scoop roller together with the supporting roller forms an adjustable slot for the passage therebetween of the metal strip.
Exact geometric relationships are produced at the point of coating, where the strip maintains its position and shape and the coating material is conveyed in sufficient supply to the same point essentially independently of fluctuations in the level of the bath. Although no additional means is pro-vided for stripping off the excess molten metal, a precisely adjustable layer thickness can be obtained even when the molten metal is conveyed in excess, since the metal strip squeezes off excess material due to the forced guidance of the molten metal. The layer thickness can be set exactly within wide limits depending on the forced guidance of the molten metal due to the scoop roller and the support of the metal strip, and this is not only the case where large amounts are to be applied, but due to the continuing good contact between the surface of the strip and the scoop roller is the case even with small amounts to be applied. The thickness of layer can be set by adjusting the pressure between the scoop roller and the support roller.
The process according to the invention is particularly suitable for producing so-called galvanealed material (steel strip material, in which the molten zinc forms an alloy with the strip material), when according to ~.
~ - 3 -~265'33 one arrangement using zinc as the molten metal and steel as the strip mate-rial, the molten metal has a temperature of 450C to 480C and the strip temperature is from 530C to 650C, in particular 570, and quantity of molten zinc applied is restricted during application to the amount necessary for an alloy with the strip material. In addition, the danger of overflowing the edges of the strip is avoided by maintaining these ranges in temperature and thereby also maintaining a specific range of viscosity of the molten metal.
In this process the increase in temperature of the coating material necessary for the formation of the alloy is achieved by the heat of the strip material. ~his is directly possible with the necessary low amounts of coat-ing material to be applied. An advantage over known processes is that the molten coating material does not need any ceramic container~ due to its low temperature. Since the strip material is not directed through the melting bath but comes into contact with the melting bath only indirectly, and since the low application amount of molten coating material scooped is practically completely applied, i.e. no excess passes back into the melting bath, the melting bath is practically not heated further. Neither is an additional serially connected furnace needed, as was the case previously, to heat the costed strip material to the temperature necessary for formation of the alloy.
The strip materia] reaches the necessary temperature with the necessary annealing prior to the coating procedure. Then cooling is less intense than previously. With æinc as the coating material and steel as the strip mate-rlal, temperatures of 450 C to 480 C have proved favourab]e for the melting bath and 530C to 650 C for the strip material.
Preferably the scoop roller is immersed in the melting bath over more than half of its periphery. It is possible with this embodiment to convey lar~er application amounts into the nip without the scoop roller _ ~ _ ` ~Z6593 having its o~m drive means, since the liquid metal adhering to the scoop rol-ler exerts considerably lower restoring moments on the scoop roller than with a scoop roller which is only slightly immersed in the bath. Furthermore, in the case of a scoop roller which is more than half immersed in the bath there is less tendency for molten metal to flow back into the bath than in the case of a scoop roller which is only slightly im~ersed.
It has been found that with a scoop roller which is immersed too deeply in the bath there is danger of the molten metal flowing over the edges of the strip. In order to both eliminate this danger and apply the molten metal optimumly the scoop roller should pro~ect 10 to 45 mm, in particular 10 to 15 mm, out of the melting bath.
Preferably the diameter of the supporting and deflection roller should be ~ubstantially larger than the diameter of the scoop roller, in particular about double the size thereof. It is here advantageous when the diameter of the scoop roller is relatively small, in particular 150 to 350 mm, preferably about 250 mm.
Both the supporting and deflection roller and the scoop roller can be mounted to be freely rotatable. In this case, they are rotated by the strip running between them. In order to eliminate the danger of the roller coming to a standstill, the strip can be directed round the supporting and de~lection roller over a large angle of contact.
If a particularly thick layer is required, not only is a cor-respondingly wide passage slot or nip set between the scoop roller and the cupporting and deflection roller, but also the scoop roller is immersed to a correcponding depth in the melting bath. It can be of advantage here if the surface of the scoop roiler also has a high bonding strength for the molten metal due to roughening or suchlike. Further, the supply of the molten metal into the nip can be influenced by the speed of the surface of i, .. . .
- ~ :
~,~6593 the scoop roller being altered by means oP a drive means. If the speed of the surface of the scoop roller is greater than that of the strip, more molten metal is conveyed into the nip, if the speed of the surface of the scoop roller, however, is less than that of the strip, less molten metal is conveyed into the nip.
A preferred embodiment of the invention is explained in more detail below by means Or the drawing which represents the embodiment schematically.
; A container 1 is filled with molten metal 2, e.g. zinc. A cover-ing hood 3, which is open at the bottom, is immersed in the melting bath 2 at its lower edge. An inclined channel 4 and a vertical channel 5 lead into said covering hood 3. The channel 4 has a sluice-type inlet 6 and the chan-nel 5 has a sluice-type outlet 7.
A supporting and deflection roller 8 is freely rotatable above the level of the melting bath 2 and at a short distance therefrom. A scoop roller 9, which is substantially smaller in dia~eter than the supporting and deflection roller 8, is arranged below the latter, the axis of the scoop roller 9 being arranged parallel to the axis of the supporting and deflection roller 8 and in the same vertical plane. The scoop roller 9 is immersed in the melting bath 2 by more than half its surface area. The scoop roller 9 can be freely ~ournaled or actuated by an ad~ustable drive means.
The cleaned and heated strip material 12 to be coated runs over the aluice-type inlet 6, the channel 4 into the area of the covering hold 3 which is under an atmo8phere of protective gas. Here it is deflected by the sup-porting and deflection roller 8 and passed vertically upwards through chan-nel 5 and the sluice-type outlet 7. The strip material 12 loops the sup-porting and deflection roller 8 over an angle of about 135C. Thereby, exact guidance is achieved at only a short distance from the level of the bath.
:, .
'` ' ~26593 The scoop roller 9, which touches the surface of the strip material 12, transports molten metal into the nip 10 when the strip moves. The molten metal is applied with the desired thickness dependine on the selected dis-tance set between the two rollers 8,9. Excess metal is thereby squeezed off and flows back into the melting bath 2. Contrary to the known process of the German Offenlegungsschrift 2 712 003, however, the applied layer here can be set exactly independent of fluctuations in the level of the bath, as the molten metal is conveyed by the scoop roller to the surface of the strip which iB fixed in position and thus constant relationships are ensured. The setting of the thickness of layer is also more exact than is the case with the other known process of the United States patent 3 228 788, as contrary thereto the application amount here is not metered before the area of application but at the area of application itself. This means that in the process according to the invention high quality strip material can be pro-duced with different layer thicknesses while maintaining very close tol-erances. Maintaining close tolerances is not only of advantage for further processing but also means that considerable amounts of coating material are saved.
Although the layer thickness can be set exactly with a low cost in apparatus in the process according to the invention, ad~ustable nozzle strippers known per se can be additionally provided. Such nozzle strippers can be set at a height above the level of the melting bath, at a distance from the surface Or the bath and at the angle at which the gas jet is blown onto the bath. It has proved particularly advantageous to arrange the ~tripping nozzles at a height of lOO to 250 mm, in particular of about 150 mm, above the level of the melting bath. Since coating is carried out under an atmosphere of protective gas, it is, of course, necessary to also operate the nozzle strippers with a corresponding protective gas, e.g. nitrogen or .
'. ' , ' ' : .- :
1~65~
argon.
Zinc coatings on a steel strip often show large areas of crystal patterns (flowers of zinc), which are particularly undesirable when the galvanized surface of the strip is placed on the visible side of a structural part. This flower formation can be prevented very simply and effectively by blowing a nucleus forming agent, e.g. zinc or zinc oxide dust, onto the zinc layer when still liquid together with the gas jet of the stripping nozzles in accordance with a preferred feature of the invention.
The molten zinc in the melting bath is covered by a floating layer (not shown) of a substance which is insoluble in and/or not wettable by the molten zinc. This floating layer prevents or minimizes evaporation of the molten zinc, and may be particulate in nature, for example comprising a single layer or several layers of graphite balls. The effect of this layer is to improve the quality of the product. If eva~oration of the zinc is not ~revented. zinc vapor tends to condense within the covering hood 3 above the melting bath, and may drop as zinc dust onto the metal strip being processed, so that the reverse surface of the strip, or the strip before it is coated becomes dirty, thus necessitating an additional cleaning operation.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for coating one side of a metal strip with a molten metal from a melting bath, comprising the steps of continuously conveying a previously cleaned and heated metal strip through a protective gas atmosphere partially around a supporting roller and above the level of the melting bath of the molten metal for bringing the metal strip into contact with the molten metal, supporting the metal strip on a rear or reverse side thereof on the supporting roller in the area of contact with the molten metal, and conveying the molten metal from the melting bath towards the supported area of the strip with a scoop roller immersed in the melting bath by more than half its surface area but only by part, which scoop roller together with the supporting roller forms an adjustable slot for the passage therebetween of the metal strip.
2. The process according to claim 1, wherein said molten metal is zinc and said metal strip is formed of steel.
3. The process according to claim 1, wherein the molten metal has a temperature between 450°C. to 480 C., and the temperature of the strip is between 530°C. and 650°C.
4. The process according to claim 3, wherein the strip temperature is 570°C. and the amount of the molten metal is restricted during application to the amount necessary to alloy with the strip material.
5. The process according to claim 1, wherein said molten metal is molten zinc and comprising the step of preventing said molten zinc from evaporating by using a substance which is non-soluble with the molten zinc.
6. The process according to claim 1, wherein said molten metal is zinc and comprising the steps of floating a substance on the top of the melting bath which is non-soluble and non-wettable by the molten zinc to prevent the molten zinc from evaporating.
7. The process according to claim 1, wherein said molten metal is zinc and comprising the steps of associating a substance with the melting bath which is non-wettable by the molten zinc to prevent the molten zinc from evaporating.
8. The process according to claim 5, 6 or 7, wherein said substance includes a plurality of graphite balls covering the molten zinc in at least one layer.
9. The process according to claim 5, 6 or 7, wherein said substance consists of a plurality of graphite balls, and a plurality of layers of said graphite balls covering the molten zinc.
10. The process according to claim 1, wherein said supporting step includes the step of supporting the obverse side of the metal strip above the level of the melting bath, and said conveying step includes the raising of the molten metal to the obverse side by said scoop roller.
11. The process according to claim 1 including the step of blowing a nucleus forming agent comprising a material selected from the group consisting of zinc and zinc oxide dust onto the metal coated strip.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2819142.6 | 1978-04-29 | ||
| DE2819142A DE2819142C2 (en) | 1978-04-29 | 1978-04-29 | Method and device for one-sided coating of a metal strip with molten metal, in particular for one-sided hot-dip galvanizing of steel strip |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1126593A true CA1126593A (en) | 1982-06-29 |
Family
ID=6038468
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA326,614A Expired CA1126593A (en) | 1978-04-29 | 1979-04-30 | Coating of metal strip on one side with molten metal |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5511188A (en) |
| BE (1) | BE875893A (en) |
| CA (1) | CA1126593A (en) |
| DE (1) | DE2819142C2 (en) |
| FR (1) | FR2424329B1 (en) |
| GB (1) | GB2019896B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3101760A1 (en) * | 1981-01-21 | 1982-07-29 | Mannesmann AG, 4000 Düsseldorf | "METHOD AND DEVICE FOR ONE-SIDED COATING OF CONTINUOUS BAND" |
| JPS59129758A (en) * | 1983-01-14 | 1984-07-26 | Hitachi Cable Ltd | Production of one-side plated bar by molten metal |
| DE3313218C2 (en) * | 1983-04-13 | 1985-11-14 | Mannesmann AG, 4000 Düsseldorf | Device for optional one-sided and double-sided galvanizing of endless steel strip |
| FR2556743A1 (en) * | 1983-12-14 | 1985-06-21 | Burilov Georges | Machine for tin-plating metal plates and more particularly printed circuit boards |
| WO2006056346A1 (en) | 2004-11-23 | 2006-06-01 | Wieland-Werke Ag | Method and production line for coating one face of metal strips and associated use of said strips |
| AT500851B8 (en) * | 2005-02-25 | 2007-02-15 | Voestalpine Mechatronics Gmbh | DEVICE FOR MELT DIPPING OF METAL STRIPS |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR962471A (en) * | 1950-06-10 | |||
| US2775954A (en) * | 1955-12-14 | 1957-01-01 | Eastman Kodak Co | Roller coating apparatus |
| GB905611A (en) * | 1957-10-01 | 1962-09-12 | Technograph Printed Circuits L | Improvements in and relating to the coating of metallic surfaces |
| US3086879A (en) * | 1958-03-05 | 1963-04-23 | Frederic H Lassiter | Metallized products and foils and method of forming the same |
| US3228788A (en) * | 1962-05-04 | 1966-01-11 | United States Steel Corp | Method and apparatus for galvanizing steel strip on one side |
| GB1004496A (en) * | 1962-12-20 | 1965-09-15 | Ferranti Ltd | Improvements relating to methods of and apparatus for applying a metal coating to a base member |
| FR2067338A1 (en) * | 1969-11-17 | 1971-08-20 | Femipari Kutato Intezet | Preparing aluminium or aluminium alloy strip for welding |
| JPS568908B2 (en) * | 1973-03-20 | 1981-02-26 | ||
| FR2288792A1 (en) * | 1974-08-26 | 1976-05-21 | Prezelin Maurice | Coating substrates with molten metal from a bath - contg dosing and coating rollers, plus a roller removing excess metal |
| US4082868A (en) * | 1976-03-18 | 1978-04-04 | Armco Steel Corporation | Method for continuously contact-coating one side only of a ferrous base metal strip with a molten coating metal |
| JPS52141431A (en) * | 1976-05-21 | 1977-11-25 | Kawasaki Steel Co | Device for fabricating one side plated steel plate |
| US4103644A (en) * | 1976-09-16 | 1978-08-01 | Michels Norman C | Apparatus for coating one side only of strip material |
-
1978
- 1978-04-29 DE DE2819142A patent/DE2819142C2/en not_active Expired
-
1979
- 1979-04-25 FR FR797910521A patent/FR2424329B1/en not_active Expired
- 1979-04-26 BE BE0/194871A patent/BE875893A/en not_active IP Right Cessation
- 1979-04-26 GB GB7915688A patent/GB2019896B/en not_active Expired
- 1979-04-27 JP JP5157779A patent/JPS5511188A/en active Granted
- 1979-04-30 CA CA326,614A patent/CA1126593A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2019896B (en) | 1982-12-01 |
| BE875893A (en) | 1979-08-16 |
| JPS5511188A (en) | 1980-01-25 |
| DE2819142A1 (en) | 1979-10-31 |
| GB2019896A (en) | 1979-11-07 |
| FR2424329B1 (en) | 1985-07-26 |
| DE2819142C2 (en) | 1982-03-25 |
| JPS6363625B2 (en) | 1988-12-08 |
| FR2424329A1 (en) | 1979-11-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3916042A (en) | Process for the application of an adhesive layer in alloy welding | |
| CA1126593A (en) | Coating of metal strip on one side with molten metal | |
| US4917717A (en) | Apparatus for and process of coating glass | |
| US4239817A (en) | Process and apparatus for coating one side of a metal strip with molten metal | |
| US4728353A (en) | Process and apparatus for pyrolytically coating glass | |
| KR100358829B1 (en) | Coating plant | |
| SE461218B (en) | SETTING AND DEVICE CREATING A COAT OF A METAL COMPOUND ON A HOT GLASSY SUBSTRATE | |
| SE462968B (en) | MAKE A COATING OF A METAL OR METAL SOCIETY ON A SURFACE OF A JUST IMAGED GLASS BAND | |
| US4880698A (en) | Coated flat glass | |
| JP2003013193A (en) | Method for manufacturing hot-dip galvanized steel sheet | |
| US4945973A (en) | Thermal conductivity of substrate material correlated with atomizing gas-produced steady state temperature | |
| JPH05311388A (en) | Method and device for continuous hot-dip metal coating of metallic sheet | |
| KR800000533B1 (en) | Continuous plating apparatus for steel strip | |
| US5086727A (en) | Thin film forming apparatus having adjustable guide | |
| SE454270B (en) | SET AND DEVICE FOR PREPARING A COATED LODGE COVER ON A METALLIZED EDGE OF A GLASS DISC | |
| JPH03287752A (en) | Continuous hot dipping device for band steel | |
| JPH0129238Y2 (en) | ||
| JPH02170958A (en) | Hot dipping method | |
| JP2951177B2 (en) | Metal strip hot dip coating equipment | |
| JPH02111864A (en) | Production of hot dip plated metal sheet | |
| JP2981412B2 (en) | Method and apparatus for manufacturing hot-dip metal-plated steel sheet | |
| JP4123948B2 (en) | Manufacturing method and apparatus for manufacturing minimum spangled galvanized steel sheet | |
| JPH02111861A (en) | Method for hot dip plating metal sheet | |
| JPH04325662A (en) | Uniform hot-dip plating method | |
| JPS58110667A (en) | Adjusting method for coating weight of galvanizing on one side |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |