US3681118A - Method of removing excess molten metal coatings by employing low pressure gas streams - Google Patents

Method of removing excess molten metal coatings by employing low pressure gas streams Download PDF

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US3681118A
US3681118A US14491A US3681118DA US3681118A US 3681118 A US3681118 A US 3681118A US 14491 A US14491 A US 14491A US 3681118D A US3681118D A US 3681118DA US 3681118 A US3681118 A US 3681118A
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coating
metal
gas
strip
steel strip
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Tsuyoshi Ohama
Tetsuji Iwasaki
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Hitachi Ltd
Nippon Steel Nisshin Co Ltd
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Hitachi Ltd
Nisshin Steel Co Ltd
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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

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  • the present invention relates to a method and apparatus for continuous hot dip metal coating wherein compressed gas is directed onto opposite faces of a metal strip, e.g. steel, continuously drawn out of a molten coating metal bath.
  • the pressurized gas blows away any excess metal from the deposited metal film.
  • the amount of metal coating has generally been controlled by suitably selecting the diameter and peripheral velocity of coating rolls, the shape and pitch of grooves provided on the coating rolls, the height between the center of coating rolls and the coating metal bath surface, the fluidity of molten metal in the coating metal bath, the moving velocity of the steel strip, and other factors.
  • Another defect involved in the prior method has been the inclusion of oxides in the coated metal film by the coating rolls. This oxide inclusion results in poorly finished surfaces of a coated steel strip and also provides restriction in the coating speed.
  • This prior method has been also defective in that, although a relatively thin coating can be obtained as described previously, by wiping the coated film with the asbestos wipers while it is still in its nonsolidified state, any wear of the asbestos causes an unsatisfactory wiping operation which results in the appearance of streaks due to the presence of excess metal on the coated film. This leads to a loss of the desirable external appearance, workability and the feasibility of painting.
  • the prior method exhibits further shortcomings in that a time of several hours to several days is wasted in exchanging the coating rolls when surface roughness develops thereon. Also, the rolls must be changed to deal with the requirements for variation of thickness of the coating.
  • An object of the present invention is to provide an improved method and apparatus for continuous hot dip metal coating, which provides not only the production of a higher quality steel strip of uniform coating thickness having no oxide inclusion, but also eliminates various defects inherent in the prior art methods of using coating rolls, such as, the difliculty in controlling the coating thickness, loss of the plating metal, oxide inclusion, time loss in exchanging the coating rolls and the unavoidable limitation in coating velocity.
  • a metal strip for example, steel
  • a gas under pressure preferably at a low pressure
  • FIG. 1 is a diagrammatic side elevational view of a prior apparatus for continuously coating by hot dipping
  • FIG. 2 is a partly cut-away perspective view of an apparatus for continuously coating by hot dipping embodying the method and apparatus according to the present invention
  • FIG. 3 is a side elevational view of the apparatus of FIG. 2;
  • FIG. 4 is a partly cut-away perspective view of another embodiment of the apparatus embodying the method according to the present invention.
  • FIG. 5 is a side elevational view of the apparatus of FIG. 4.
  • FIG. 6 is a diagram showing the relation between the gas pressures and the amount of coating material deposited on one surface of the steel strip representing the results of adjusting the coating thickness achieved by varying gas pressures.
  • a method and apparatus for hot dip coating comprising moving a continuous metal strip through a bath containing a coating material and then upwardly away from said bath. During its upward movement and while the coating is still in its non-solidified state, a gas is directed under pressure onto either side of the coated metal strip in a. direction opposite to the direction of movement of the metal strip, to remove excess coating material from the coated strip.
  • a method and apparatus for continuously coating a metal strip by hot dipping, without the use of coating rolls comprising moving a continuous steel strip through a coating metal bath and then upwardly away from said bath.
  • a pair of nozzles is disposed on opposite sides of the coated steel strip in a manner such that their openings are directed in a direction opposite to the advancing direction of the steel strip and extend transversely of the steel strip.
  • Said openings have a size of about 0.3 to 3 millimeters and are adjustably spaced from the steel strip at a distance of about 3 to 20 millimeters.
  • a gas at a pressure of about 0.05 to 1 kilogram per square centimeter gauge is directed onto the steel strip faces at an angle of about 3 to 45 degrees with respect to the normal to the steel strip faces while the coated metal films are still in the non-solidified state, thereby blowing away any excess metal from the metal films.
  • metal films of any desired thickness can be formed on the opposite faces of the steel strip.
  • Apparatus for carrying out the above method may comprise a bath for the coating material, means for moving a continuous metal strip through the bath and guiding it upwardly away from the bath and gas directing means including nozzles located such that in the operation of the apparatus, gas, under pressure, is directed from the nozzles onto either side of the metal strip during its upward movement while the coating is still in its non-solidified state.
  • the gas is directed opposite to the direction of movement of the metal strip to remove any excess coating maerial from the strip.
  • the present invention is advantageous in that the thickness of coated films on opposite faces of a metal strip such as steel can accurately and freely be controlled by the use of a gas at a low pressure. It is possible to eliminate every defect previously encountered in the use of solid means such as coating rolls, for example, the occurrence of nonuniformity in the coated film thickness including excessively thick coatings on opposite edge portions of the steel strip, and the lowering of the coating efliciency due to the time required for exchanging the coating rolls.
  • the present invention provides further advantages in that an extremely thin coating such as that which can be obtained by electroplating can be obtained more readily and at a higher speed than with the prior methods. Thus a coated steel strip of good quality which is suitable for multiple purposes can be manufactured at an extremely low cost.
  • a further advantage derivable from the present invention is that damage on the coated film due to contact by nozzles or the closing of the nozzle openings by the moving strip can readily be avoided.
  • FIG. 1 Before giving detailed description of the method and apparatus of the present invention, a prior method of continuously coating by hot dipping will first be described with reference to FIG. 1 so that the invention can be clearly understood.
  • a moving steel strip A is continuously conveyed through a molten zinc bath 3, being guided therethrough by a feed roll B and a bottom roll 1.
  • the strip is coated with zinc by the action of a pair of coating rolls C, C disposed at the molten zinc bath surface while the strip A is moved upwardly away from the bath 3.
  • the strip is guided in its upward movement by a deflector roll 2.
  • a pair of asbestos wipers D, D are disposed directly above the molten zinc bath 3 to Wipe away any excess metal while the zinc coating is still in its non-solidified state.
  • the method according to the present invention eliminates all of the defects encountered with the prior method and will be described in detail with reference to FIGS. 2 to -5 of the drawings.
  • a steel strip 4 is continuously moved upwardly through a zinc coating bath 3 by being guided by a bottom roll 1 and a deflector roll 2. Adjacent the opposite sides of the coated strip 4 as it moves in the upward direction away from the coating bath 3, there are disposed an opposing pair of stationary frame members 6 and 7, positioned at right angles with respect to the moving direction of the strip 4. These frame members 6 and 7 are provided with hollow spaces which are adapted to slidably receive slider means 8. Nozzles 5, are swinga'bly mounted at opposite ends in the opposite sliders 8, 8 so that the gas ejection angle of the nozzles 5 with respect to the strip faces can be freely selected within a range of about 3 to 45.
  • the nozzles 5, 5 are disposed on opposite sides of the steel strip 4 and have a similar mounting structure therefor.
  • a slot 9 is provided in each slider 8 and receives therein a pin 12 extending from one end of a bellcrank 11 pivotally mounted on a pivot provided on the external face of the corresponding frame member 6.
  • a pin 13 extending from the other end of the bellcrank 11 is connected to a piston rod 15 extending from a hydraulic cylinder 14 secured on the same external face of the frame member.
  • the nozzles 5 can thus be moved toward and away from the strip faces independently of each other by suitably supplying a fluid at pressure to the hydraulic cylinders 14 and discharging the fiuid therefrom.
  • each slider means 8 which is opposite to the steel strip 4, is slope-shaped, and a wedge 25 is disposed in the hollow space in a manner so as to engage this sloped face of the slider means 8.
  • a screw 16 is provided on the wedge 25 to cause vertical movement of the latter by vertical movement of the former so that the slider means 8 can be slightly moved in either direction, thereby effecting close adjustment of the spacing between the nozzles 5, 5 and the steel strip 4.
  • Bafile plates 17, 17 are disposed below the respective nozzles 5, 5 to prevent any turbulence of the plating bath due to gas streams ejected from the nozzles 5, 5.
  • a pair of lower holding rolls 18, 18 disposed :below the coating bath surface and a pair of upper holding rolls 19, 19 disposed above the gas ejection nozzles 5, 5 are freely rotated by the force of frictional contact with the steel strip 4 and are operative to prevent any swinging movement of the steel strip 4, thereby maintaining the rectilinearity of the steel strip 4 during its passage between the nozzles 5.
  • Opposite ends of each upper holding roll 19 are each fixed to a slider 20 which is laterally slidable by the action of a rod 21 actuated as by a servomotor.
  • the two sliders 20, 20 on the same side are received in a slider 22 which is connected to a rod 23 for providing a vertical sliding movement.
  • Sliders 20 and 22 are received in a frame member 24.
  • resilient means such as an elastic liquid or a spring may be employed to impart to the rolls 19, 19 a suitable pressure which does not develop any strong frictional contact between the rolls 19, 19 and the steel strip 4. Furthermore, a good result may be obtained by adapting the upper holding rolls 19, 19 in such a manner that they can follow any movement of the steel strip 4 in its transverse direction.
  • Nozzle spacing 6 to 40 (10 to 30 50. 8 to 101.6.
  • (A) Size of the nozzle openings The size of the nozzle openings in the British patent is very small, that is, in a range of 0.127 to 0.381 millimeter as compared with a nozzle opening of about 0.3 to 3 millimeter as compared with a nozzle opening .of about 0.3 to 3 millimeters as defined by the present invention. This makes it necessary to rely on highly skilled workman to manufacture nozzles having a uniform opening throughout the entire length along the width of the strip.
  • (B) Nozzle spacing The nozzle spacing in the British patent is very large that is, in a range from 50.8 to 101.6 millimeters as compared with a nozzle spacing of about 6 to 40 millimeters as defined in the present invention. With such a large nozzle spacing, that is, greater than 20 mm. between the nozzle and the strip or 40 mm. between nozzles, it is necessary to use a proportionally high gas ejection pressure in order to obtain the end of throttling the gas stream as desired. This inevitably results in a lowering of the temperature near the nozzle openings and a production of turbulent flow of air in the neighborhood of the nozzle openings which interfers with the streams of gas ejected through the nozzles.
  • the temperature decrease of the gas occurs unevenly along the entire width of the strip resulting in a lack of uniformity on the wiping effect. This makes it impossible to obtain satisfactory finished coated surfaces.
  • the atmosphere in the operation chamber exerts a greater influence on the control of the quantity of coating metal applied to the opposite faces of the steel strip than in the case where a smaller nozzle to steel strip distance, is utilized, as in the present invention.
  • the control of the quantity of coating material can only be effected in an unstable manner when large nozzle to strip distances are utilized.
  • the spacing between the nozzle openings and the steel strip is below about 3 millimeters flaws and lack of uniformity are liable to occur on the coated faces due to minute vibrations of the steel strip. In addition, frequent occurrences of nozzle blacking result.
  • the preferred spacing has been found to be in the range of 5 to millimeters.
  • the quantity of coating metal applied to the opposite faces of the steel strip can be controlled mainly by varying the pressure at which the gas is ejected, the nozzle spacing, and the size of the nozzle openings which define the amount of flow of gas, as well as by varying the angle at which the gas is ejected and the temperature of the gas.
  • the control of the quantity of coating material applied to the opposite faces of the steel strip is effected greatly by various factors as stated above and it becomes impossible to effect accurate and precise adjustments of the quantity of coating material. This causes variations in the quality of the products produced. This is substantiated by a comparison made between the present application and the British patent in operation conditions and the quantity of coating metal deposited on the steel strip, as will be subsequently described.
  • the present invention provides an effective and stable control of the coating process and results in the production of products which are free from variations in quality.
  • the downwardly directed air substream tends to cause splashing of the molten coating metal from the surface of the molten metal coating bath, thereby causing obstruction of the nozzles or enhancement of the phenomenon of oxidation of the bath surface.
  • the gas is ejected at a low pressure in a range of about 0.05 to 1.0 kilogram per square centimeter gauge, which is characteristic of the present invention, it is possible to achieve a spectacular wiping effect. That is, the use of a low pressure entirely eliminates ripples and inherently causes a reduction in the pressure of the downwardly directed air substream, so that occurrences of splashes of the metal coating from the surface of the molten coating metal bath are greatly reduced.
  • This feature avoids abstruction of the nozzles which poses a problem when a pressure of over 1.0 kilogram per centimeter gauge is used. It also eliminates any possible oxidation of the surface of the molten metal bath coating.
  • the pressure ranges of the present application and those of the British patent overlap each other. It is noted that 0.83 kilogram per centimeter gauge is the lower limit of the range in the British patent and that the quantity of coating metal deposited on the steel strip is at a maximum when the gas is ejected at this pressure level. However, in the invention, 1.0 kilogram per square centimeter gauge is the upper gas pressure limit and the quantity of coating metal deposited is at a minimum at this pressure. It is thus evident that there is a clear distincition between the British patent and the present invention.
  • Table 2 shows the comparison between the present application and the British patent with reference to the size of nozzle openings, the nozzle spacing and the gas ejection pressure stated hereinabove.
  • the present application can achieve far better results than the British patent. It should also be noted that the present application is superior to the British patent in controlling the quantity of coating metal applied to a steel strip.
  • the quantity of coating metal applied to a steel strip can be controlled by adjusting the gas ejection pressure, the nozzle spacing and the size of the nozzle openings as aforementioned.
  • adjustments of each of these factors can bring about a variation in the quantity of coating metal applied to the steel strip in a precise and orderly manner.
  • the present application permits the continuous variation in the thickness of a coating material in small steps over a wide range from a very thin gauge coating to a thick coating in a stable manner which is beyond the scope of a coating process using rolls.
  • the British patent does not permit process control in the manner described above and cannot effect control of the quantity of coating material in a stable manner, much less produce a very thin gauge coating product.
  • Amounts of Spacing Gas Distance deposited coat- Gas between directing from liquid Nozzle Gas Rate of strip ing material Examples, operation pressure, nozzles, angle, level in the opening, temperamovement, (on opposite number 1b.lin. in. degrees bath, in. in. ture, F. f.p.m. faces) oz./it.
  • FIG. 6 wherein the quantitles of metal coating applied are plotted as ordinates against the pressures at which the gas is ejected as abscissae
  • the embodiments of the present application and the British patent are compared.
  • the quantities of coating metal applied in the present application vary at a constant rate but variations in the British patent cannot be followed to any logical conclusion.
  • the fact that variations in the quantities of coating metal applied in the British patent cannot be followed clearly can be shown by the following description which is based on Table 3 (which shows the embodiments of the British patent).
  • the nozzle spacing in operation 8 is 2 inches which is smaller than the nozzle spacing of 3 inches in operation 11, so that quantity of metal coating would be reduced to a larger extent in the former than in the latter.
  • the ejection angle, the height from the bath surface, the size of nozzle openings, the temperature of steam and the line rate all indicate that the quantity of metal coating applied in operation 8 would be reduced below that applied in operation 11.
  • the actual results are reversed that is, the quantity of coating metal applied is from 0.5 to 0.8 oz./ft. in operation 11 and from 1.25 oz./ft. in operation 8.
  • the line rate of operation 1 is f.p.m. which is lower than f.p.m. in operation 6, indicating that the quantity of coating metal applied in operation 1 would be lower than that applied in operation 6.
  • the pressure and the nozzle spacing indicate that the quantity of coating metal applied in operation 6 would be lower than that applied in operation 1. It appears that these factors combined to produce the result that the 11 quantities of coating metal applied in operation 1 and operation 6 are substantially equal.
  • the present invention provides a stable metal coating operation.
  • the gas ejection pressure, the size of the nozzle opening and the nozzle spacing are main factors in comtrolling the quantity of coating metal applied to a steel strip, and that the temperature of ejected gas, the angle of ejection and the rate of movement of the steel strip play subordinate roles.
  • the present invention defines the ranges of values of the three principal factors, that is, the gas ejection pressure, the size of the nozzle openings and the nozzle spacing, which, in combination, produce unobvious results as contrasted to the results achieved by the British patent.
  • the results achieved by the combination of features of the present invention are as follows:
  • the quantity of coating metal applied to a steel strip can be controlled in a stable manner as desired, and the thickness of a coating applied to the steel strip can be varied easily from a very thin gauge to a thick gauge over a wide range;
  • Samples A and B have been prepared to show the difference of surface smoothness due to the operating conditions according to Table 5.
  • Sample A was formed by the method of the British patent and Sample B was produced by the method of the present invention. The two specimens were compared by viewing their surface at an oblique angle under a strong light. Sample A exhibited a small crystal structure with many irregular dark patches and particularly parallel rippling lines. However, Sample B contained a bright, calender-looking surface with higher reflectivity. A large dendritic crystal structure could be observed with a noted absence of irregular dark areas and/or ripping lines. The results of these tests are shown in Table 5 below.
  • FIG. 6 shows the relation between the gas pressures and the amount of coating material deposited on one surface of the steel strips
  • EXAMPLE 1 A steel strip 2.3 millimeters thick and 1000 millimeters wide was conveyed at a rate of 30 meters per minute for providing a zinc coating thereon. Nozzles having an opening of 0.9 millimeter were disposed at an ejection angle of 30 degrees with respect to the normal to the faces of the steel strip. The height of the nozzles above the coating bath was 250 millimeters and each nozzle was spaced 5 millimeters from the strip face. Combustion gas at a temperature of 500 C. and at a pressure of 0.5 kilogram per square centimeter gauge was directed towards the steel strip faces in a direction opposite to the advancing direction of the steel strip. As a result of this gas ejection, a uniform zinc coating could be attained with a coating on each face of 0.175 ounce per square foot.
  • EXAMPLE 2 A steel strip 0.5 millimeter thick and 1000 millimeters wide was conveyed at a rate of meters per minute for providing a zinc-aluminum coating thereon. Nozzles having an opening of 1 millimeter were disposed at an ejection angle of 15 degrees with respect to the normal to the faces of the steel strip. The height of the nozzles above the coating bath was 250 millimeters and each nozzle was spaced 7 millimeters from the strip face. Combustion gas at a temperature of 400 C. and at a pressure of 1 kilogram per square centimeter gauge was directed towards the steep strip faces in a direction opposite to the advancing direction of the steel strip. As a result of this gas ejection, a uniform zinc-aluminum coating could be attained with a coating on each face of 0.075 ounce per square foot.
  • EXAMPLE 3 A steel strip 1.5 millimeters thick and 1000 millimeters wide was conveyed at a rate of 25 meters per minute for providing a zinc coating thereon. Nozzles having an opening of 0.6 millimeter were disposed at an ejecting angle of 8 degrees with respect to the normal to the faces of the steel strip. The height of the nozzles above the coating bath was 250 millimeters and each nozzle was spaced millimeters from the strip face. Combustion gas at a temperature of 450 C. and at a pressure of 0.18 kilogram per square centimeter gauge was directed towards the steel strip faces in a direction opposite to the advancing direction of the steel strip. As a result of this gas ejection a uniform zinc coating could be attained on each face of 0.35 ounce per square foot.
  • EXAMPLE 4 A steel strip 0.8 millimeter thick and 1000 millimeters Wide was fed at a rate of 40 meters per minute for providing a zinc-aluminum coating thereon. Nozzles having an opening of 0.9 millimeter were disposed at an ejecting angle of 10 degrees with respect to the normal to the faces of the steel strip. The height of the nozzles above the coating bath was 160 millimeters and each nozzle 5 was spaced 20 millimeters from the strip face. Combustion gas at a temperature of 460 C. and at a pressure of 0.06 kilogram per square centimeter gauge was directed towards the steel strip faces in a direction opposite to the advancing direction of the steel strip. As a result of this gas ejection a uniform zinc coating could be attained with a coating on each face of 0.615 ounce per square foot.
  • EXAMPLE 5 A steel strip 0.3 millimeter thick and 1000 millimeters wide was fed at a rate of 70 meters per minute for providing a zinc coating thereon. Nozzles having an opening of 0.85 millimeter were disposed at an ejecting angle of 5 degrees with respect to the normal to the faces of the steel strip. The height of the nozzles above the coating bath was 200 millimeters and each nozzle was spaced 8 millimeters from the strip face. Combustion gas at a temperature of 440 C. and at a pressure of 0.25 kilogram per square centimeter gauge was directed towards the steel strip faces in a direction opposite to the advancing direction of the steel strip. As a result of this gas ejection a uniform zinc coating could be attained with a coating on each face of 0.3 ounce per square foot.
  • EXAMPLE 6 A steel strip 0.4 millimeter thick and 1000 millimeters wide was conveyed at a rate of 60 meters per minute for providing a zinc coating thereon.
  • the nozzles having an opening of 0.9 millimeter were disposed at an ejecting angle of 5 degrees with respect to the normal to the faces of the steel strip.
  • the height of the nozzles above the coating was 160 millimeters and each nozzle 5 was spaced 11 millimeters from the strip face.
  • Combustion gas at a temperature of 450 C. and at a pres sure of 0.3 kilogram per square centimeter guage was directed towards the steel strip faces in a direction opposite to the advancing direction of the steel strip. As a result of this gas ejection a uniform zinc coating could be attained with a coating on each face of 0.25 ounce per square foot.
  • EXAMPLE 7 A steel strip of 0.6 millimeter thick and 1000 millimeters wide was introduced at a rate of 50 meters per minute for providing a zinc coating thereon.
  • the nozzles having an opening of 0.3 millimeter were disposed at an ejecting angle of 7.5 degrees with respect to the normal to the faces of the steel strip.
  • the height of the nozzles above the coating bath was 200 millimeters and each nozzle 5 was spaced by 10 millimeters from the strip face.
  • Combustion gas at a temperature of 470 C. and at a pressure of 1.5 kilograms per square centimeter gauge was directed towards the steel strip faces in a direction opposite to the advancing direction of the steel strip.
  • this gas ejection an almost uniform zinc coating could be attained with a coating 14 on each face of 0.4 ounce per square foot.
  • ripples on the surface thereof there was observed the occurrence of ripples on the surface thereof.
  • a steel strip 104 is continuously moved upwardly through a coating bath 103 by being guided by a bottom roll 101 and a deflector roll 102. Adjacent the opposite edges of the steel strip 104 moving upwardly away from the coating bath 103, there are disposed opposed pairs of stationary frame members 113 and 114 at right angles with respect to the moving direction of the strip 104. These frame members 113 and 114 are provided with hollow spaces therein in each of which is slider 115' is slidably received.
  • Compressed gas supply pipes 105, 105 each having an opening directed towards the strip face are disposed on opposite sides of the steel strip 104 in parallel relation therewith and are swingably mounted at opposite ends in the opposite sliders 115, 115.
  • An apron-like member 126, 126 is mounted on each gas supply pipe 105 so that these apron-like members 126, 126 are disposed on opposite sides of the steel strip 104 to define gas spaces between them and the strip 104.
  • Each apron-like member 126, 126 has a substantially horizontal upper wall 106 and a parabolically sloped lower wall 111 defining a throat 112 between it and the opposite steel strip face.
  • Roll-like or plate-like sealing members 109, 109 of soft, resilient and heat resisting material such as asbestos or glass fiber are disposed in parallel on opposite sides of the steel strlp 104 in sealing contact therewith and are each rotatably or fixedly mounted on a support frame 107 which is slidable on guides 108, 108 provided on the opposite frame members 113 and 114.
  • a piston rod 110 is connected at one end thereof to the center of each support frame 107 at right angles therewith and is connected at the other end to a piston received in a hydraulic cylinder fixedly mounted on a support bar bridging the opposite frame members 113 and 114.
  • a slot 116 is provided in each slider and receives therein a pin 119 extending from one end of a link 11 8 pivotally mounted on a pivot 117 provided on the external face of the corresponding frame member 113, while a pin 120 extending from the other end of the link 118 is connected to a piston rod 122 of a piston received in hydraulic cylinder 121 secured on the same external face of the frame member 113.
  • the compressed gas supply pipes 105, 105 can be moved towards and away from the strip faces in unitary relation with the apron-like members 126, 126 and the throats can be made wider or narrower as desired by supplying a fluid at pressure into the cylinders 121, 121 and discharging it therefrom.
  • each slider 115 which is opposite to the steel strip 104 is slope-shaped, and a wedge 123 is disposed in the hollow space in a manner to engage with this sloped face of the slider 115.
  • a screw 124 is provided under the wedge 123 to cause vertical movement of the latter by vertical movement of the former so that close adjustment of the positions of the compressed gas supply pipes 105, 105 and the apron-like members 126 126 can thereby be effected.
  • a compressed gas for example, compressed air, inert gas such as nitrogen gas, or exhaust gas of combustion is supplied at room temperature or in a heated state from the gas supply pipes 105, 105 while the deposited film on the coated steel strip 104 moving upwardly away from the coating bath 103 is still in its non-solidified state, jet streams of gas caused by the throats 112, 112 flow downwardly along steel strip faces to blow away any excess metal from the coated films on the plated steel strip 104.
  • the sealing members 109 are operative to correct any non-uniformity in the film thickness and to prevent any vibration of the steel strip 104 during the coating operation, with the result that the coated film of excellent quality can be obtained.
  • Bathe plates 125, 125 are disposed below the respective throats 112, 112 in order to avoid turbulence of the coating bath 103 due to the jet streams of gas.
  • gas similar elfects can be obtained by use of nitrogen gas, air or steam.
  • gas temperature to be employed for the zinc or zinc-aluminum coating room temperature may be acceptable but the optimum temperature is from about 200 to 500 C. It will easily be understood that the present invention is also applicable to the coating of steel strips with tin, tin-lead or aluminum as well as coating other metal strips with various metal coatings.
  • a method of continuous hot-dip coating of a metal strip which comprises conveying a continuous metal strip through a coating metal bath, removing the coated metal strip from the bath, directing streams of a gas from a pair of gas-distributing means having apertures of about 0.3 to 3 millimeters, in a direction opposite to the direction of movement of the metal strip at an angle of about 3 to 30 degrees with respect to the normal to the metal strip faces and under a pressure of about 0.05 to 1.0 kg./ cm.
  • said gas streams being directed at the metal strip at a distance of about 3 to millimeters from the faces of said strip and while said metal coating is still in an unsolidified state, to remove excess coating metal from the coated metal strip, whereby coatings of any desired thickness can be formed on the opposite faces of the metal strip.
  • a method of continuous hot-dip coating of a metal strip which comprises conveying a continuous metal strip through a coating metal bath, removing the coated metal strip from the bath, directing streams of a gas from a pair of gas-distributing means having apertures about 0.3 to 3 millimeters, in a direction opposite to the direction of movement of the metal strip at an angle of about 3 to 30 degrees with respect to the normal to the metal strip faces and under a pressure of about 0.1 to 0.5 kg./ cm.
  • said gas streams being directed at the metal strip at a distance of about 3 to 20 millimeters from the faces of said strip and while said metal coating is still in an unsolidified state, to remove excess coating metal from the coated metal strip, whereby coatings of any desired thickness can be formed on the opposite faces of the metal strip.

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  • Engineering & Computer Science (AREA)
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  • Metallurgy (AREA)
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US14491A 1965-06-08 1970-02-26 Method of removing excess molten metal coatings by employing low pressure gas streams Expired - Lifetime US3681118A (en)

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JP3424465 1965-06-08
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US (1) US3681118A (enrdf_load_stackoverflow)
BE (1) BE681831A (enrdf_load_stackoverflow)
DE (1) DE1521288A1 (enrdf_load_stackoverflow)
GB (1) GB1131951A (enrdf_load_stackoverflow)

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US3719164A (en) * 1971-05-10 1973-03-06 Sun Oil Co Dip coating apparatus including fluid doctor means
US3779206A (en) * 1971-01-20 1973-12-18 Fuji Photo Film Co Ltd Apparatus for scraping liquid off of sheet material
US3808029A (en) * 1970-09-25 1974-04-30 Lysaght Ltd John Lead-zinc wet-flux galvanizing process
US3924794A (en) * 1973-08-14 1975-12-09 Us Energy Solder leveling process
US3930075A (en) * 1973-12-26 1975-12-30 United States Steel Corp Method for controlling splashing resulting from the use of gas knives
US3932683A (en) * 1972-10-10 1976-01-13 Inland Steel Company Control of coating thickness of hot-dip metal coating
US3988517A (en) * 1975-05-19 1976-10-26 United States Steel Corporation Gas knife process for controlling hot-dip aluminum coatings
US3998181A (en) * 1973-09-07 1976-12-21 Aggust Thyssen-Hutte Ag Apparatus for scraping metal coating on hot-coated metal strips
US4078103A (en) * 1975-04-17 1978-03-07 Armco Steel Corporation Method and apparatus for finishing molten metallic coatings
US4107357A (en) * 1975-09-16 1978-08-15 Nippon Steel Corporation Method for effecting one side molten metal plating
US4207362A (en) * 1977-11-21 1980-06-10 Australian Wire Industries Proprietary Limited Method of and apparatus for wiping hot dipped metal coated wire or strip
EP0038975A1 (en) * 1980-04-11 1981-11-04 Bethlehem Steel Corporation Gas wiping apparatus and method of using
US4315056A (en) * 1977-05-04 1982-02-09 Armco Inc. Low tin terne coated steel article
WO1987002857A1 (en) * 1985-10-30 1987-05-07 Hollis Automation, Inc. Mass soldering system
US5066519A (en) * 1988-08-24 1991-11-19 Australian Wire Industries Pty. Limited Jet wiping nozzle
US5221345A (en) * 1990-10-12 1993-06-22 National Galvanizing Inc. Method and apparatus for coating a strip
US5651819A (en) * 1993-06-24 1997-07-29 The Idod Trust Continuous tube forming and coating
US6333075B1 (en) * 1997-04-24 2001-12-25 Bridgestone Corporation Method of forming a film on strip material and apparatus thereof
EP1586672A1 (en) * 2004-04-13 2005-10-19 Mitsubishi-Hitachi Metals Machinery, Inc. Liquid wiping apparatus
WO2018025222A1 (en) * 2016-08-05 2018-02-08 Medea S.R.L. Device for the controlled reduction of the thickness of metallic coatings obtained with the technique of the hot bath in molten metal
CN109477198A (zh) * 2016-07-13 2019-03-15 杰富意钢铁株式会社 熔融金属镀覆钢带的制造方法以及连续熔融金属镀覆设备
WO2019057635A1 (de) * 2017-09-19 2019-03-28 Thyssenkrupp Steel Europe Ag Schmelztauchbeschichtetes stahlband mit verbessertem oberflächenerscheinungsbild und verfahren zu seiner herstellung
US10550459B2 (en) * 2016-01-29 2020-02-04 Centre De Recherches Metallurgiques Asbl-Centrum Voor Research In De Metallurgie Vzw Device for hydrodynamic stabilization of a continuously travelling metal strip
US11535905B2 (en) 2017-08-22 2022-12-27 Thyssenkrupp Ag Use of a Q and P steel for producing a shaped component for high-wear applications
WO2023037881A1 (ja) * 2021-09-10 2023-03-16 Ｊｆｅスチール株式会社 溶融金属めっき鋼帯の製造方法

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US3619247A (en) * 1968-08-29 1971-11-09 Bethlehem Steel Corp Method of producing thin, bright unspangled galvanized coatings on ferrous metal strips
JPS5891162A (ja) * 1981-11-18 1983-05-31 Nisshin Steel Co Ltd 溶融亜鉛めつき鋼板の製造方法
WO2014135753A1 (fr) 2013-03-06 2014-09-12 Arcelormittal Investigacion Y Desarrollo, S.L. Procédé de réalisation d'une tôle à revêtement znal avec un essorage optimisé, tôle, pièce et véhicule correspondants

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3808029A (en) * 1970-09-25 1974-04-30 Lysaght Ltd John Lead-zinc wet-flux galvanizing process
US3779206A (en) * 1971-01-20 1973-12-18 Fuji Photo Film Co Ltd Apparatus for scraping liquid off of sheet material
US3719164A (en) * 1971-05-10 1973-03-06 Sun Oil Co Dip coating apparatus including fluid doctor means
US3932683A (en) * 1972-10-10 1976-01-13 Inland Steel Company Control of coating thickness of hot-dip metal coating
US3924794A (en) * 1973-08-14 1975-12-09 Us Energy Solder leveling process
US3998181A (en) * 1973-09-07 1976-12-21 Aggust Thyssen-Hutte Ag Apparatus for scraping metal coating on hot-coated metal strips
US3930075A (en) * 1973-12-26 1975-12-30 United States Steel Corp Method for controlling splashing resulting from the use of gas knives
US4078103A (en) * 1975-04-17 1978-03-07 Armco Steel Corporation Method and apparatus for finishing molten metallic coatings
US3988517A (en) * 1975-05-19 1976-10-26 United States Steel Corporation Gas knife process for controlling hot-dip aluminum coatings
US4107357A (en) * 1975-09-16 1978-08-15 Nippon Steel Corporation Method for effecting one side molten metal plating
US4315056A (en) * 1977-05-04 1982-02-09 Armco Inc. Low tin terne coated steel article
US4207362A (en) * 1977-11-21 1980-06-10 Australian Wire Industries Proprietary Limited Method of and apparatus for wiping hot dipped metal coated wire or strip
EP0038975A1 (en) * 1980-04-11 1981-11-04 Bethlehem Steel Corporation Gas wiping apparatus and method of using
WO1987002857A1 (en) * 1985-10-30 1987-05-07 Hollis Automation, Inc. Mass soldering system
US4664308A (en) * 1985-10-30 1987-05-12 Hollis Automation, Inc. Mass soldering system providing an oscillating air blast
US5066519A (en) * 1988-08-24 1991-11-19 Australian Wire Industries Pty. Limited Jet wiping nozzle
US5221345A (en) * 1990-10-12 1993-06-22 National Galvanizing Inc. Method and apparatus for coating a strip
US5279667A (en) * 1990-10-12 1994-01-18 National Galvanizing Inc. Method and apparatus for coating a strip
US5651819A (en) * 1993-06-24 1997-07-29 The Idod Trust Continuous tube forming and coating
US5860204A (en) * 1993-06-24 1999-01-19 The Idod Trust Continuous tube forming and coating
US6333075B1 (en) * 1997-04-24 2001-12-25 Bridgestone Corporation Method of forming a film on strip material and apparatus thereof
EP0953382A3 (en) * 1998-04-27 2002-10-02 Bridgestone Corporation Method of forming a film on a strip material and apparatus thereof
US8079323B2 (en) 2004-04-13 2011-12-20 Mitsubishi-Hitachi Metals Machinery, Inc. Liquid wiping apparatus
US20050247262A1 (en) * 2004-04-13 2005-11-10 Mitsubishi-Hitachi Metals Machinery, Inc. Liquid wiping apparatus
US20080295766A1 (en) * 2004-04-13 2008-12-04 Masashi Yoshikawa Liquid wiping apparatus
EP1586672A1 (en) * 2004-04-13 2005-10-19 Mitsubishi-Hitachi Metals Machinery, Inc. Liquid wiping apparatus
US10550459B2 (en) * 2016-01-29 2020-02-04 Centre De Recherches Metallurgiques Asbl-Centrum Voor Research In De Metallurgie Vzw Device for hydrodynamic stabilization of a continuously travelling metal strip
CN109477198A (zh) * 2016-07-13 2019-03-15 杰富意钢铁株式会社 熔融金属镀覆钢带的制造方法以及连续熔融金属镀覆设备
EP3486351A4 (en) * 2016-07-13 2019-05-22 JFE Steel Corporation METHOD FOR PRODUCING A PLATED METAL MELTING METAL STRIP AND INSTALLATION FOR CONTINUOUS METAL MELTING PLATING
US11104983B2 (en) * 2016-07-13 2021-08-31 Jfe Steel Corporation Method of producing hot-dip metal coated steel strip and continuous hot-dip metal coating apparatus
WO2018025222A1 (en) * 2016-08-05 2018-02-08 Medea S.R.L. Device for the controlled reduction of the thickness of metallic coatings obtained with the technique of the hot bath in molten metal
IT201600082676A1 (it) * 2016-08-09 2018-02-09 Medea S R L Dispositivo di riduzione controllata dello spessore dei rivestimenti metallici ottenuti con la tecnica del bagno a caldo
US11535905B2 (en) 2017-08-22 2022-12-27 Thyssenkrupp Ag Use of a Q and P steel for producing a shaped component for high-wear applications
WO2019057635A1 (de) * 2017-09-19 2019-03-28 Thyssenkrupp Steel Europe Ag Schmelztauchbeschichtetes stahlband mit verbessertem oberflächenerscheinungsbild und verfahren zu seiner herstellung
US11655531B2 (en) 2017-09-19 2023-05-23 Thyssenkrupp Steel Europe Ag Hot dip coated steel strip having an improved surface appearance and method for production thereof
EP3684959B1 (de) 2017-09-19 2023-08-23 ThyssenKrupp Steel Europe AG Schmelztauchbeschichtetes stahlband mit verbessertem oberflächenerscheinungsbild und verfahren zu seiner herstellung
EP4253592A3 (de) * 2017-09-19 2023-11-08 ThyssenKrupp Steel Europe AG Schmelztauchbeschichtetes stahlband mit verbessertem oberflächenerscheinungsbild und verfahren zu seiner herstellung
WO2023037881A1 (ja) * 2021-09-10 2023-03-16 Ｊｆｅスチール株式会社 溶融金属めっき鋼帯の製造方法
AU2022341700B2 (en) * 2021-09-10 2025-07-03 Jfe Steel Corporation Method for Manufacturing Hot-Dip Metal-Coated Steel Strip

Also Published As

Publication number Publication date
BE681831A (enrdf_load_stackoverflow) 1966-10-31
GB1131951A (en) 1968-10-30
DE1521288A1 (de) 1970-02-12

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