EP0111039A1 - Verfahren zum kontinuierlichen Tauchverzinken und Anlassen eines Metalldrahtes mit grosser Geschwindigkeit - Google Patents

Verfahren zum kontinuierlichen Tauchverzinken und Anlassen eines Metalldrahtes mit grosser Geschwindigkeit Download PDF

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Publication number
EP0111039A1
EP0111039A1 EP82402240A EP82402240A EP0111039A1 EP 0111039 A1 EP0111039 A1 EP 0111039A1 EP 82402240 A EP82402240 A EP 82402240A EP 82402240 A EP82402240 A EP 82402240A EP 0111039 A1 EP0111039 A1 EP 0111039A1
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Prior art keywords
wire
zinc
aluminum
bath
coating
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EP82402240A
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English (en)
French (fr)
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James W. Hogg
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
    • B21C37/04—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire
    • B21C37/042—Manufacture of coated wire or bars
    • 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
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • 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
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • 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
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • C23C2/29—Cooling or quenching

Definitions

  • the present invention relates to the field of galvanizing metal wire such as a steel wire to produce a metal wire resistant to corrosion, having a shiny, silvery luster, and it relates more particularly to continuous manufacturing, at high speed and in line with a low carbon galvanized steel wire which can be annealed without destroying the corrosion resistant coating or its silvery luster in order to produce a more ductile galvanized metal wire having improved strength corrosion.
  • US-A-3,730,758 describes a process for galvanizing steel strips by vacuum coating the steel strip with a metal, for example zinc, by vacuum deposition or by electro-deposition followed by quenching hot to apply a second coating of zinc.
  • a metal for example zinc
  • the first coating under vacuum can be of aluminum because an addition of aluminum is usually made in galvani baths sation in order to reduce the formation of an interface alloy of zinc with the surface of the strip.
  • this document neither describes a stretching or forming phase after galvanizing, nor the advantage of a lower speed required during the galvanizing phase and a higher speed for annealing, nor any phase of annealing to eliminate the constraints introduced by the stretching or forming phase, or even the provision of means by which the galvanized strip could be annealed without harming the shiny silvery shine of the zinc coating.
  • U.S. - A - 101,264, 2,286,073, 2,288,762 and 2,482,978 each describe methods of galvanizing a metal wire followed by drawing to lengthen the wire and decrease its thickness. None of these patents describes, teaches or suggests the use of an annealing operation after stretching in order to release the stresses generated by stretching, and to decrease the hardness and increase the ability during forming, drawn galvanized wire. If annealing was done after drawing, it is believed that the wire would have an unpleasant, rough and dark finished appearance due to significant oxidation.
  • US - A - 2,378,458 describes a process for pre-coating a copper steel wire or delaying the formation of a zinc-iron alloy following galvanization and for making the coating of zinc more ductile and easier to work .
  • This document does not describe, teach or suggest annealing after drawing the galvanized metal wire to release the stresses generated by the drawing operation or that it would result in a shiny silver finish of the wire.
  • US - A - 2.152.842 and 2.326.629 describe the coating of steel billets with a paint containing 70 parts of aluminum, 23 parts of ammonia salt and 7 parts of zinc to protect the billets from surface deterioration during subsequent reheating to hot rolling temperatures.
  • the paint combines with the steel billet during the hot forming operation. Subsequent working and modification of the alloy with the steel billet is necessary to give the alloy a degree of pliability and, after hot rolling, the billet can be cleaned and alloyed with zinc.
  • a second metal can be used, for example aluminum or zinc which is united, on the surface in the form of a strip or by progressive solidification. or other process involving the alloy and using aluminum and zinc powders. Despite this complicated process, the part is still susceptible to separation from the coating of the steel billet and special shells are required to prevent separation.
  • the resulting galvanized-annealed wire has an unpleasant gray surface due to the oxidation of the surface layer of zinc and the roughness due to cracking of the coating and is not suitable for drawing due to the increased brittleness which is imparted by the growth of iron-zinc alloy layers.
  • the invention relates to a method of hot-dip galvanizing and annealing, continuously at high speed, a ferrous metal wire which moves continuously, to produce a metal wire having a high corrosion resistance. , more ductile, having a shiny silver luster, comprising, according to a preferred embodiment, the phases consisting in passing the ferrous metal wire in continuous movement after it has been cleaned, through an electroplating bath of zinc to deposit a coating of zinc on the wire, and then through a molten bath maintained at a temperature of about 390 to about 419 ° C comprising a major part of zinc and an amount of aluminum sufficient to achieve in the galvanizing bath an eutectic alloy having a melting point lower than that of zinc (for example approximately 420 ° C.) but not lower than the melting point of the eutectic alloy of zinc and aluminum containing 5% by weight of aluminum based on the combined weight of the zinc and aluminum alloy in the bath to coat the wire with zinc and aluminum.
  • the present invention is based on the discovery that significant thicknesses of a coating of zinc and - from about 4 to about 6% aluminum can be applied and solidified on a ferrous metal wire to not only provide protection and give a silvery sheen to the wire, but also allow the wire to be drawn to a smaller cross section without total loss of the coating or without sacrificing the gloss or the resistance to corrosion after annealing.
  • a zinc coating is first applied electrolytically to the wire in order to reinforce the bonding properties for a layer then applied from 4% to 6 1 o of aluminum-zinc. This aspect is extremely advantageous when thicker wire is to be galvanized in the range of about 0.71 mm or more and provides a stronger bond even when thinner wire is to be galvanized.
  • the alloy bond formed by the process of hot dipping in zinc is notably slowed down and sometimes stopped by aluminum which inhibits the iron-zinc reaction.
  • the zinc pre-coating applied by the electrolytic device is not significantly removed by dissolution when the pre-coated wire is subjected to hot dipping, since the temperature of the hot dipping bath is kept below the melting point zinc.
  • Relatively notable thicknesses are obtained by keeping the temperature of the hot-dipping bath below the melting point of zinc, namely approximately 419.6 ° 0, but notably above the melting point of the aluminum-zinc bath (by example about 382 ° C for a 5% Al-Zn bath) and this is based largely on the use of the lower melting point of the eutectic alloy of zinc and about 5% aluminum which is sufficient below the zinc melting point to allow application of the aluminum-zinc eutectic alloy below the zinc melting point, so that zinc coatings already adhere over the wire are not easily removed.
  • the electrolytic application of the zinc pre-coating before hot dipping in the Al-Zn eutectic alloy can be eliminated, so that after cleaning the wire it is done directly in the eutectic alloy bath Al-Zn in fusion.
  • the variant of the process finds use in particular for thin wires, for example having a diameter of about 0.71 mm or less, which tend to heat more quickly to temperatures of iron-zinc alloy than thicker wires.
  • the metal wire is passed after cleaning through the bath of iron-zinc eutectic alloy as described above.
  • the bath temperature may need to be raised above the range specified in the preferred process, that is, to about 560 ° C or more.
  • the residence time in the molten bath can be extended to help promote a limited effect of iron-zinc alloy.
  • the extent of the iron-zinc alloy effect is limited to achieve an appropriate bond between the zinc coating and the metal wire in order to maintain the coating on the wire and is not significant enough to cause embrittlement of the coating. -which would cause stretching difficulties and / or an unpleasant and rough appearance of the wire.
  • the invention is also based on the use of the extremely large increase in the speed of the wire after drawing and the high annealing speed, for example of 760 meters per minute, without encountering unwinding problems.
  • the speed of the wire coming out of a stretching machine can increase up to five times or more than five times the speed of the wire entering the machine.
  • the invention takes advantage these speed differences by galvanizing before stretching and annealing after stretching.
  • the time-temperature imperatives of hot dip galvanizing, the heat limitations due to the electrical resistance of a wire in the electrolytic process, and the mechanical limitations of the apparatus impose these slower speeds for galvanizing.
  • the slower galvanization rates provide adequate time for the limited iron-zinc alloy reaction to occur in the process variant.
  • the iron-zinc alloy reaction in the molten bath is a function of time and temperature. In the case of the preferred method, adequate time is required to increase the thickness of the aluminum-zinc alloy coating to the desired degree. In both methods there is a consideration of speed which is due to the mechanics and dynamics of the galvanizing system which can cause twists and / or too great a tension of the wire when excessively high speeds are used. Thus, after the wire has been coated with the aluminum-zinc alloy coating, with or without a prior electrolytic coating of zinc, it is drawn to a significantly smaller section.
  • the continuously moving low carbon drawn ferrous wire undergoes an annealing treatment at temperatures of about 704 ° C or more for a short period of time sufficient to release the stresses imposed on the wire by the phase of stretching but not long enough to overcome the inhibitory effect of aluminum content in the coating on the inherent effect of iron-zinc alloy and against oxidation.
  • the annealed wire is soaked and packaged as desired.
  • the wire can be passed through a polishing die if the soaking bath is a lubricant or after soaking in the conventional process.
  • the polishing die can be of a suitable size for a reduction of 10% or less and is used to smooth and thus make the coating even more shiny.
  • the wire Before applying the zinc pre-coating or the aluminum and zinc coating on the wire, the wire must be properly cleaned in any manner suitable for use in the galvanizing industry.
  • a convenient means for cleaning is, for example, the non-contact electrolytic cleaner containing 8 to 16% sulfuric acid by volume and maintained at a temperature of about 60 ° C or less.
  • the wire is passed through electrodes which make it alternately cathodic and anodic.
  • the electrolytic effect releases hydrogen and oxygen at the wire.
  • the bubbling effect obtained removes oxides and impurities from the wire. Any other suitable means may be used for cleaning the wire.
  • the wire is then passed directly through an electrolytic zinc plating machine in which a coating of zinc is applied to the wire.
  • the passage of the wire from the cleaning mechanism to 1 1 electroplating device is fast enough to prevent oxidation of the surface of the wire.
  • Any suitable electroplating zinc plating device can be used and a zinc coating which is for example 3 to 7 microns thick is applied to the surface of the wire, which means that the zinc coating increases the overall wire radius by an additional 3 to 7 microns and increases the overall diameter by twice that amount.
  • the temperature of the electrolytic bath in the electroplating apparatus can vary from 30 to 70 ° C and densities can be used current of more or less 1.08 amperes per square centimeter, compatible with the speed and the diameter of the wire.
  • the residence time in the electrolytic bath varies depending on many factors, such as the temperature of the bath, the diameter of the wire, the desired thickness of the coating, the current densities, the concentration of zinc ions in the bath and other factors. , the relationships of which are well known in the art.
  • residence times of 13 to 15 seconds are suitable for a wire with a diameter of 0.69 mm to obtain a zinc coating of an appropriate thickness with approximately 21.2 meters of wire exposed to the electrolyte with a speed of 98.8 meters per minute.
  • the wire After applying a zinc coating to the wire, for example with a thickness of 3 to 7 microns, the wire is rinsed with water to wash off the residual electrolyte and it is then wiped with air to remove excess water. It is then quickly passed into the hot soaking bath containing the molten aluminum-zinc eutectic alloy containing a sufficient quantity of aluminum to produce a eutectic alloy having a melting point lower than that of zinc; the eutectic alloy contains approximately 4 to 6% aluminum and preferably more precisely 5% aluminum.
  • the hot dip bath can be of any suitable construction and equipment of different types is available and / or is described in the prior art.
  • the temperature of the hot dipping bath should be kept in the range of about 390 to about 418.8 ° C, in order to ensure the application of an appropriate thickness of an aluminum-zinc coating on the wire .
  • the melting point of mixtures with approximately 4 to 6% aluminum and zinc extends from about 388 ° C, which is the approximate melting point of aluminum-zinc mixtures at 4 to 6%, up to about 382 ° C which is the melting point of aluminum-zinc mixtures at 5% aluminum. These temperatures are well below the melting point of approximately pure zinc which is about 419.6 ° C.
  • temperatures above 382 ° C, and preferably 390 ° C and above are suitable for keeping the hot dipping bath in the molten state and that temperatures below about 418.8 ° C are low enough to avoid complete melting or dissolution of the zinc already plated on the wire.
  • temperatures below about 418.8 ° C are low enough to avoid complete melting or dissolution of the zinc already plated on the wire.
  • temperatures that are much lower than the melting point of zinc while being higher than the melting point of the eutectic mixture of aluminum and zinc in the hot bath.
  • the thickness of the coating of aluminum-zinc eutectic alloy applied in the hot dipping bath is approximately 3 to 7 microns, and preferably approximately 3 to 5 microns.
  • the residence time of the wire in the hot dip bath depends on many factors including the diameter of the wire to be coated. Thicker wires normally require a longer time to start the reaction between zinc and iron which provides an adequate bond for the coating. This consideration would, however, be secondary in cases where a prior electrolytic zinc coating has been applied to the wire. In general, the residence time of the wire which has not been previously coated is considerably longer than for the wires previously coated in the bath of eutectic alloy for hot dipping. Uncoated wires cannot be galvanized much faster than 91 m / m while for previously coated wires can reach 152 m / m.
  • Uncoated wires should be subjected to much higher temperatures in the 5 ⁇ l al-zn bath than in a simple molten zinc bath to achieve adequate bonding, for example a wire with a diameter of about 1.25 mm should be subjected to a temperature of approximately 560 ° C for approximately one second to obtain an adequate bond with the eutectic alloy. A shorter time even imposes higher temperatures.
  • the wire leaves the aluminum-zinc hot dipping bath, it is preferable to pass it through a calibration die or an appropriate wiping die to smooth the aluminum and zinc coating and maintain a diameter overall uniform of the coated wire. At this point the wire presented to the stretching machine has a soft external galvanizing skin which facilitates the stretching because it acts as a lubricant.
  • the preferred process is almost if not completely free of the hard alloys of iron and zinc found in hot dip galvanizing.
  • the substrate made of pure electrolytic zinc in the preferred process makes the galvanized wire superior to that obtained by the galvanizing process by a hot dipping phase when it is presented to the machine.
  • the wire After exiting the hot dipping bath, the wire is passed immediately coated in a soaking in water maintained at room temperature, to rapidly reduce the temperature of the coated wire and ed u ire and thus prevent oxidation of the coating surface is lying. After soaking with water, the wire is subjected to the action of a wiping with air to dry it.
  • the wire is then passed through a drawing machine of any suitable type in which its cross section is reduced.
  • the reduction in cross section can vary up to a reduction of 95%, and preferably from 65 to 90%.
  • the percentage reduction is measured by subtracting the final cross section of the wire after drawing from its initial cross section before drawing, the difference is divided by the initial cross section and multiplied by 100.
  • the drawing operation is carried out at room temperature although the temperature of the wire increases significantly due to the mechanical work of the wire. Depending on the total reduction, the operation wire drawing increases its speed dramatically. For example, the speed of a wire having a diameter of 1.9 mm stretched to a diameter of 0.695 increases from about 100 to 103 m / m before stretching to about 760 m / m after stretching.
  • All operations performed before stretching namely cleaning, electroplating, hot soaking and water soaking are all carried out at a speed of about 60 m / m or less up to about 167 m / m or more.
  • All subsequent stretching operations are carried out at a speed of about 456 m / m or less to about 760 m / m or more.
  • Normal speeds of entry to a drawing machine, and therefore speeds of galvanization rise up to 167 m / m with exit or annealing speeds being able to rise up to approximately 760 m / m or more.
  • significant stresses develop in the wire, making it relatively more fragile and less ductile.
  • the wire is then annealed so that the aluminum-zinc coatings are not significantly reduced or destroyed and under these conditions the coating is not made more fragile or weakly bonded to the wire by due to the fact that the action of iron-zinc-aluminum alloy has been excessively favored or that under these conditions the surface of the coating is oxidized or otherwise adversely affected.
  • the electro-galvanizing process there is enough aluminum in the overlay to diffuse through the underlying zinc to the substrate steel to inhibit this growth of the alloy .
  • the annealing operation must therefore be carried out quickly and under conditions such that the stresses are relaxed and the effect of inhibiting the aluminum content in the coating is not sufficiently overcome to make the coating fragile in a way undesirable due to the action of iron-zinc alloy, or to give it a dark and rough appearance, or less resistant to corrosion due to oxidation.
  • the coated wire is guided vertically downwardly through an induction coil having characteristics suitable for heating the wire to a temperature of 649 to 815 ° C with a residence time d '' about 0.29 seconds or less up to 0.48 seconds or more.
  • the vertical arrangement of the wire tends to avoid the formation of a cross section in a drop of water due to the flow of the coating under the action of gravity and tends to keep the circular configuration in section of the wire.
  • the wire is wound several times around the upper capstan to prevent the application of any forces from the upstream direction. Leaving the induction winding, the wire is wound several times around the lower capstan so that any downstream constraints are prevented from affecting the wire which passes through the induction winding.
  • the annealed wire After leaving the induction coil, the annealed wire is immediately passed through an oil bath to rapidly decrease its temperature to prevent oxidation.
  • the aforementioned lower capstan can itself be mounted in the oil bath.
  • the temperature of the oil bath must be maintained at room temperature for effective soaking.
  • a typical example of a reduction in the tension of a thread would be from about 8,788 kg / cm 2 to about 5,273 kgjcm 2 .
  • a polishing or finishing die can be used if desired in the oil bath in order to reinforce the surface appearance of the annealed galvanized wire by reducing the wire to the desired final dimension and by smoothing and re -distribution of the coating uniformly around the wire and to remove most of the residual oil.
  • the wire is then wound up by a stationary block or another suitable member or device for winding the wire from where it is dropped on the rod of a conveyor or it can be wound by a machine on a reel.
  • the wire can instead be passed through a water soaking bath and then the wire can be wiped with air and can pass it through a lubricating die after it has left the soaking tank.
  • the lubricated die finishes or polishes the coated wire to smooth the coating evenly around the wire.
  • the wire is then passed to a stationary block or other suitable mechanism for winding or wrapping the wire in any other way. If a polishing die is used, the reduction percentage is normally less than 10%.
  • the process according to the invention is applicable to a wide range of wire sizes from No. 34 (diameter of 0.26 mm), or thinner, to No. 9 (3.76 mm in diameter) or thicker
  • the calibration system that is used here is that of the "Steel Wire Gauge" which is widely accepted in the industry.
  • the process according to the invention is in particular preferred for galvanizing, drawing and annealing thin wires, that is to say of No. 17 (diameter 1.37 mm) or thinner because of the significant economic advantages procured by the invention and the inability to date of galvanizing metal wire in batches.
  • N ° 9 wire is a little more than fourteen times the diameter of a N ° 34 wire, the latter (2.322 m / kg) is more than two hundred times longer per kilo than the N wire ° 9 (11.42 m / kg).
  • Wire N ° 17 (283 m / kg) represents only a third of the diameter of a wire N ° 9 but is more than seven times longer.
  • the invention makes it possible to carry out the unwinding, cleaning and galvanizing operations at relatively low controllable speeds to ensure better control of these operations while at the same time allowing high production rates for the finished product.
  • the corrosion resistance is enhanced by the process according to the invention both at ambient temperatures and at elevated temperatures by the 5% Al-Zn coating when compared to zinc.
  • An area of almost 5% Al-Zn is extremely effective against corrosion in industrial and salt water atmospheres as well as in applications at high temperatures.
  • the relative corrosion current zinc and the coating to 5% Al-Zn were 4.3 milliamps per cm 2 and 1, 8 milliamps per cm 2, respectively.
  • the environment was a solution of 0.1 NH 2 SO 4 + 3.5% NaCL.
  • the 5% Al-Zn coating had a corrosion resistance that exceeded that of zinc by about 2.4 times.
  • the invention has also obtained better resistance to corrosion at high temperatures. Complete destruction of zinc at annealing temperatures has been observed; however, the 5% Al-Zn coating withstood temperatures around 760 ° C for short periods.
  • the wire 12 moves from the supply reel 10 at a speed of about 150 meters per minute in the apparatus 14 to be stretched.
  • the wire is reduced by stretching in the apparatus 14 from a diameter of 1.32 mm to a diameter of 0.56 mm, the wire lengthens with a consecutive increase in speed. There is a total reduction of 82% in the cross section of the wire.
  • the drawn wire 12 leaves the device 14, it travels at about 700 meters per minute and continues at this speed until it is wound on the stationary support 16 and falls on the support rod 18, wound .
  • the wire makes multiple passages through an acid bath 22, in which are arranged non-conductive rollers 26 and 24 around which the wire 12 alternately passes to make passages sufficient for a adequate wire cleaning.
  • the wire 12 is then made alternately cathodic and anodic. When it passes over the positive electrode, the wire becomes cathodic. When it passes over the negative electrode, the wire becomes anodic, finally leaving the bath in the anodic mode.
  • the friction action of hydrogen and oxygen which are released on the cathode wire passing around the roller 26 and on the anode wire passing around the roller 24 respectively is well known as well as the repulsion effects with respect to the impurities on the cathode wire passing around the roller 26 and against metallic particles on the anode wire passing around the roller 2 4 .
  • the preferred bath 22 contains approximately 8% by volume of sulfuric acid and acts at a temperature of approximately 60 ° and with a pH of less than 2.
  • the wire 12 After cleaning the wire 12 enters the app a - Started 2 8 electroplating passing over a switch 30 down roller in the electrolyte 3 2 ZnS0 4 and passing around a first roller 34 non-conductive and about a second non-conductive roller 36 and returns to the switch roller 3 0.
  • an anode 38 of zinc is provided in the electrolyte 32 to the zinc sulfate to continuously replenish the bath zinc ions and the wire serves as a cathode by the application made to it of a negative charge by the contactor roller 30.
  • the wire 12 continues its path, making multiple passes as necessary to receive a plating of about 3 to about 7 microns and typically from about 3 to about 5 microns, of electrolytic zinc on the surface of the wire, thereby increasing its radius from about 5 to about 7 microns and typically from about 3 to about 5 microns.
  • the preferred electrolyte contains about 90 to 120 grams of zinc metal in the form of zinc sulfate per liter of water and about 150 to 165 grams of H 2 SO 4 per liter of water.
  • the bath acts in a temperature range of 30 to 70 ° C.
  • the current density is greater than 1.08 amperes / cm 2 and flows at approximately 1.29 amperes / cm 2 with a plating time of 8 to 9 seconds to reach approximately 5 microns in thickness of electrolytic zinc coating on the surface of the wire, that is to say that its radius is increased by approximately 5 microns.
  • the contactor roller 30 the wire 12 is rinsed with water and wiped with air.
  • the electrolytic plating apparatus 28 the wire 12 passes through a hot dip bath 40 of molten zinc containing about 5% aluminum based on the combined weights of aluminum and zinc and receives a layer additional coating of 0.5% Al-Zn.
  • the residence time of the wire 12 in the bath 40 ranges from a little more than a second to less than a second and the bath 40 is maintained at a temperature in the range of 390 to 418 ° C.
  • the wire 12 leaves the bath 40 through a dimensioning die 42 or a suitable wiping member which allows an increase in thickness due to the additional coating at 5% Al-Zn of about 2 to about 4 microns on the surface of the wire according to the dimension of the die 42.
  • the cumulative thickness of the electrolytic zinc coating and of the additional coating with 5% aluminum-zinc is typically about 5 to 7 microns (that is to say on wire radius).
  • This cumulative thickness as well as the thickness of the electrolytic substrate layer and the upper layer can be adapted to suit the particular wishes of the operator, above the range of thicknesses given above, below or within this range by a control of the time / density ratio of the current in the electrolyte bath 28, the temperature of the soaking bath 40 as well as the residence time in the bath 40, and the diameter of the hole of the die 42 for dimensioning or wiping .
  • the wire passes into the soaking bath 44 with water which is maintained at room temperature to rapidly solidify the aluminum-zinc coating and prevent oxidation due to the high temperature. After leaving the soaking bath 44 with water, it is subjected to air wiping.
  • the wire drawing apparatus 14 decreases the wire 12 to a size which is about 5-10% greater than the desired size of the finished wire.
  • the wire exits the apparatus 14 to be stretched and rises approximately 4.5 meters above the ground and around a capstan 46 with suitable turns to prevent too great tension in the wire between the capstan 46 and the capstan 48 located below it.
  • the wire 12 descends through an induction coil 50 in less than a second, reaching approximately 760 ° C. This undergoing an annealing treatment. At this temperature it exhibits only a very low tensile strength and the traction between the capstans 46 and 48 is reduced to a minimum by the multiple turns formed around each capstan.
  • the wire makes several turns around the capstan 48 located in the oil bath 52 in order to prevent the transmission of excessive tension back into the wire strand 12 situated between the capstants 46 and 48.
  • the oil bath 52 is maintained at temperature ambient and serves as a soaking bath to reduce the temperature of the wire to room temperature and also serves as a die lubricant for the polishing die 54 also located in the oil bath 52.
  • This die 54 not only serves to reduce the dimension wire 12 to the desired final dimension, but also to smooth it and distribute the coating more uniformly around the wire. Due to annealing there may be some roughness and unevenness in the distribution of the coating.
  • a water soaking bath could be used with an air wiping and a lubrication die located between the soaking water tank and the stationary block 16 or the device winding.
  • the finished wire is wound on a stationary block 16 (or on a winding machine for very fine wires), which is a commercially available element and falls by gravity to the rod of the support 18.
  • the method and apparatus described above are also useful with certain modifications for the manufacture of brass coated wire.
  • the above-mentioned electrolytic zinc bath is preceded by a copper plating bath to carry out copper plating on the wire before phase (a) of the preferred process.
  • the copper coated wire is electroplated with zinc and is then subjected to the remaining phases of the preferred process as described above, i.e., (b) it passes through a molten bath containing the aluminum-zinc eutectic alloy to apply a coating of the aluminum-zinc alloy on the copper-coated wire which is then (c) drawn to a lower cross section and then (d) annealed at a temperature which can rise up to 760 °.
  • the galvanizing baths that is to say the electrolytic zinc bath and the bath of aluminum-zinc eutectic alloy are replaced by an aqueous bath of copper sulphate which may also contain tin, for example up to 8% by weight based on the weight of copper if desired to facilitate plating of copper on the wire.
  • the wire is coated with copper which provides lubrication for the drawing operation (c) and which gives the surface of the wire an attractive uniform black color after plating of copper and the drawn wire is annealed in phase (d).
  • the wire is dipped in commercially available black passage solutions, such as compounds containing selenium and copper in slightly acidic form to promote adhesion and improve color. Copper is believed to aid in the darkening of the gray color produced by selenium which in turn readily bonds to steel to provide a metallic bond between copper and steel. Additional wiping of the lubricating oil or wax with a black dye further improves corrosion resistance, color and adhesion.
  • a water-based acrylic oil or wax produces a a glossy black surface or, alternatively, a dry film of oil which can be removed with water produces a satisfactory black surface.
  • An air knife facilitates the removal of water producing a dry film.
  • the black surface produced by soaking is amorphous, allowing oil or wax to penetrate to the metal substrate, thereby blocking the interior of black soot and also improving adhesion.
  • the above described galvanizing methods including the preferred or alternative method can be used to produce black annealed wire using commercially available darkening solutions containing copper or weakly acidic copper and selenium as a soaking bath following annealing in the induction coil, thereby producing the desired black color.
  • the substrate is thus coated with a 5% aluminum-zinc eutectic alloy which results in a highly corrosion resistant coating which is preserved as it passes through the induction coil, producing when it is blackened by the process above a black annealed metal wire very resistant to corrosion due to the 5% aluminum-zinc substrate very resistant to corrosion below the black coating.
  • the methods and apparatus described above may have additional uses and may be modified by the addition of other phases and other methods to the phases and methods described above to provide beneficial effects and form advantageous products.

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EP82402240A 1982-12-07 1982-12-07 Verfahren zum kontinuierlichen Tauchverzinken und Anlassen eines Metalldrahtes mit grosser Geschwindigkeit Withdrawn EP0111039A1 (de)

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EP82402240A EP0111039A1 (de) 1982-12-07 1982-12-07 Verfahren zum kontinuierlichen Tauchverzinken und Anlassen eines Metalldrahtes mit grosser Geschwindigkeit

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0113255A2 (de) * 1982-12-24 1984-07-11 Sumitomo Electric Industries Limited Hitzebeständiger galvanisierter Eisendraht
EP0132424A1 (de) * 1983-06-28 1985-01-30 TREFILUNION Société Anonyme Korrosionsbeständiger Überzug für Stahldraht
EP0647725A1 (de) * 1993-10-08 1995-04-12 Shinko Kosen Kogyo Kabushiki Kaisha Mit Eisenzink-Aluminium-Legierung beschichteter Stahldraht und Verfahren zur Herstellung
CN102430600A (zh) * 2011-11-18 2012-05-02 铜陵金力铜材有限公司 铜线拉丝机组

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1788755A (en) * 1926-09-13 1931-01-13 American Rolling Mill Co Coated metal body
FR707035A (fr) * 1930-01-25 1931-07-02 Rolls Royce Procédé permettant de faire adhérer les alliages de zinc à l'acier
US2118758A (en) * 1934-06-05 1938-05-24 Indiana Steel & Wire Company Process of making zinc-coated ferrous wire
FR1107112A (fr) * 1953-04-30 1955-12-28 Kaiser Aluminium Chem Corp Procédé de traitement des métaux et articles obtenus
GB876032A (en) * 1958-08-11 1961-08-30 British Non Ferrous Metals Res Improvements in or relating to the galvanizing of steel
DE1197488B (de) * 1960-08-29 1965-07-29 Huettenwerk Oberhausen Ag Verfahren zur Herstellung von verzinkten Stahl-draehten mit hochwertigen mechanischen Eigen-schaften
FR1473684A (fr) * 1966-04-01 1967-03-17 Bethlehem Steel Corp Objet en métal ferreux, protégé contre la corrosion par un revêtement et procédé d'application de ce revêtement
US4152472A (en) * 1973-03-19 1979-05-01 Nippon Steel Corporation Galvanized ferrous article for later application of paint coating
CA1065204A (en) * 1974-11-18 1979-10-30 Harry P. Leckie Zinc-aluminum eutectic alloy coating process and article

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1788755A (en) * 1926-09-13 1931-01-13 American Rolling Mill Co Coated metal body
FR707035A (fr) * 1930-01-25 1931-07-02 Rolls Royce Procédé permettant de faire adhérer les alliages de zinc à l'acier
US2118758A (en) * 1934-06-05 1938-05-24 Indiana Steel & Wire Company Process of making zinc-coated ferrous wire
FR1107112A (fr) * 1953-04-30 1955-12-28 Kaiser Aluminium Chem Corp Procédé de traitement des métaux et articles obtenus
GB876032A (en) * 1958-08-11 1961-08-30 British Non Ferrous Metals Res Improvements in or relating to the galvanizing of steel
DE1197488B (de) * 1960-08-29 1965-07-29 Huettenwerk Oberhausen Ag Verfahren zur Herstellung von verzinkten Stahl-draehten mit hochwertigen mechanischen Eigen-schaften
FR1473684A (fr) * 1966-04-01 1967-03-17 Bethlehem Steel Corp Objet en métal ferreux, protégé contre la corrosion par un revêtement et procédé d'application de ce revêtement
US4152472A (en) * 1973-03-19 1979-05-01 Nippon Steel Corporation Galvanized ferrous article for later application of paint coating
CA1065204A (en) * 1974-11-18 1979-10-30 Harry P. Leckie Zinc-aluminum eutectic alloy coating process and article

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0113255A2 (de) * 1982-12-24 1984-07-11 Sumitomo Electric Industries Limited Hitzebeständiger galvanisierter Eisendraht
EP0113255A3 (en) * 1982-12-24 1985-04-24 Sumitomo Electric Industries Limited Heat-resistant galvanized iron alloy wire
EP0132424A1 (de) * 1983-06-28 1985-01-30 TREFILUNION Société Anonyme Korrosionsbeständiger Überzug für Stahldraht
EP0647725A1 (de) * 1993-10-08 1995-04-12 Shinko Kosen Kogyo Kabushiki Kaisha Mit Eisenzink-Aluminium-Legierung beschichteter Stahldraht und Verfahren zur Herstellung
CN102430600A (zh) * 2011-11-18 2012-05-02 铜陵金力铜材有限公司 铜线拉丝机组
CN102430600B (zh) * 2011-11-18 2014-07-09 铜陵金力铜材有限公司 铜线拉丝机组

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