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EP0525387B1 - Methode zum Kontrollieren des Beschichtungsgewichts eines heissmetallisierten Stahlbandes - Google Patents

Methode zum Kontrollieren des Beschichtungsgewichts eines heissmetallisierten Stahlbandes Download PDF

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Publication number
EP0525387B1
EP0525387B1 EP92110677A EP92110677A EP0525387B1 EP 0525387 B1 EP0525387 B1 EP 0525387B1 EP 92110677 A EP92110677 A EP 92110677A EP 92110677 A EP92110677 A EP 92110677A EP 0525387 B1 EP0525387 B1 EP 0525387B1
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EP
European Patent Office
Prior art keywords
steel strip
frequency current
current conducting
conducting paths
magnet
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 - Lifetime
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EP92110677A
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English (en)
French (fr)
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EP0525387A1 (de
Inventor
Toshio C/O Nkk Corporation Sato
Toshio C/O Nkk Corporation Ishii
Shunichi C/O Nkk Corporation Sugiyama
Akira C/O Nkk Corporation Yada
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JFE Engineering Corp
Original Assignee
NKK Corp
Nippon Kokan Ltd
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Publication date
Priority claimed from JP3180420A external-priority patent/JP2601068B2/ja
Priority claimed from JP3180418A external-priority patent/JP2601067B2/ja
Priority claimed from JP3238762A external-priority patent/JP2556220B2/ja
Application filed by NKK Corp, Nippon Kokan Ltd filed Critical NKK Corp
Publication of EP0525387A1 publication Critical patent/EP0525387A1/de
Application granted granted Critical
Publication of EP0525387B1 publication Critical patent/EP0525387B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • C23C2/24—Removing excess of molten coatings; Controlling or regulating the coating thickness using magnetic or electric fields

Definitions

  • the present invention relates to a method for continuously plating a steel strip with molten metal, and more particularly to a method for controlling coating weight on a steel strip.
  • Sink rolls, pinch rolls and wiping nozzles are used in the prior art methods for continuously plating a steel strip with molten metal.
  • the sink rolls are positioned in a coating bath.
  • a steel strip is moved by the sink rolls and drawn out above the coating bath.
  • the pinch rolls are used for pressing the steel strip down and straightening a bowed steel strip.
  • An excess plating on the steel strip drawn out above the coating bath is removed by jetting a gas from wiping nozzles, whereby a uniform thickness of plating can be obtained.
  • an unequal coating weight on the steel strip can also make an unequal coiling of the steel strip and causes an alloying of the plating generated after plating the steel strip to be unequal. Parts of the splash attach to the steel strip again, which becomes a cause of defects of the steel strip.
  • the increase of the amount of gas from the wiping nozzles gives rise to the increase of cost and generates a noise.
  • Japanese Examined Patent Publication No. 7444/69 discloses a method wherein an eddy current is generated in a steel strip by applying a high-frequency magnetic field to the steel strip and a molten metal is removed by Lorentz force generated by the eddy current. In this case, a wiping of molten metal by means of gas is used together with the application of the high-frequency magnetic field to the steel strip.
  • a stationary electric current is flowed in a steel strip and Lorentz force generated by the stationary electric current with a static magnetic field removes an excess molten metal on the steel strip. After the excess molten metal has been removed from the steel strip, the steel strip is wiped by gas.
  • a static magnetic field is generated on a surface of a steel strip in an outward direction from the surface of the steel strip, and an excess molten metal is removed by Lorentz force generated by an induced current generated in the molten metal by movement of the steel strip and a static magnetic field. Further, the steel strip is wiped by gas.
  • Japanese Patent Applications Laid Open No. 266560/86 and No. 103353/87 disclose a method wherein an excess molten metal is moved downwardly by a moving magnetic field generated in a downward direction from the steel strip and the steel strip is wiped by gas.
  • Vibration of a steel strip and bowing of a steel strip in a width direction thereof can be the causes that coating weight on the steel strip is not uniform. Any of the above-described conventional methods has no effect on damping of vibration and straightening of bowing of the steel strip. It is described in Japanese Examined Patent Publication No. 7444/69 that a steel strip passing between coils is centered between the coils by a magnetic repulsive force. However, since a magnetic attracting force strongly acts on the steel strip as a ferromagnetic body when a high-frequency magnetic field is simply applied to the steel strip, the steel strip passing between the coils is attracted toward the coils. As a result, an unstable vibration of the steel strip is generated.
  • a method for controlling coating weight on a hot-dipping steel strip comprises the steps of:
  • the high-frequency current is desired to have 500 to 10000 Hz. When the high-frequency current has a frequency of less than 500 Hz, there is no effect. When the high-frequency current has a frequency of more than 10000 Hz, a consumption of electricity becomes extremely great.
  • high-frequency current conducting paths each parallel with each side of a steel strip are arranged near the steel strip on one side of the steel strip and on another side of the steel strip drawn out of a coating bath above the surface of molten metal in the coating bath.
  • a high-frequency current strong enough to magnetically saturate the steel strip is flowed through the high-frequency current conducting paths to induce a high-frequency current of opposite phase in the steel strip.
  • a magnetic pressure acting on surfaces of the steel strip through an interaction of this induced high-frequency current with the high-frequency current of the high-frequency current conducting paths is generated.
  • Molten metal attaching to the steel strip is wiped out by a magnetic pressure applied from both sides of the steel strip to the steel strip and the coating weight on the steel strip is controlled. Together with the control of the coating weight on the steel strip, bowing of the steel strip in a width direction and vibration of the steel strip are prevented.
  • two pairs of high-frequency current conducting paths or more can be arranged at regular intervals in the direction of movement of a steel strip.
  • the high-frequency current conducting paths near one side of the steel strip and near another side of the steel strip are positioned, substantially facing each other, the steel strip being positioned between the high-frequency current conducting paths.
  • a high-frequency current of the same phase is flowed through the facing high-frequency current conducting paths.
  • the high-frequency current conducting paths can be positioned, facing each other or without facing each other, the steel strip being positioned between the high-frequency current conducting paths.
  • the high-frequency current conducting paths face do not each other, the high-frequency current conducting paths are positioned, being shifted in the direction of movement of the steel strip.
  • Each of the high-frequency current conducting paths is arranged across the steel strip in a width direction thereof. It is unnecessary, however, to arrange the steel strip in parallel with a width direction of the steel strip.
  • the entire length of each of the high-frequency current conducting paths can be inclined relative to a width direction of the steel strip. Since the electric current flows near the edges of the steel strip at an angle of 90 ° to the direction of flow of electric current through the high-frequency current conducting path, the magnetic pressure adjacent to the edges of the steel strip inclines to weakening. To prevent the magnetic pressure from weakening near the edges of the steel strip, the entire length of each of the high-frequency current conducting paths can be inclined relative to the width direction of the steel strip or can be inclined near the edges of the steel strip.
  • Figure 2 is a side elevation showing an example of an apparatus for executing the method of the present invention.
  • Figure 3 is a front elevation showing the apparatus as shown in Figure 2.
  • Symbol I in the drawing denotes a current.
  • a steel strip S is continuously drawn from a coating bath 4.
  • High-frequency current conducting paths 1 a, 1 b are arranged in parallel with one side of a steel strip and another side of the steel strip S.
  • a high-frequency current I of the same phase is flowed through the high-frequency current conducting paths 1 a, 1 b, an electric current having a phase opposite to the phase of the high-frequency current I flows through the steel strip S.
  • Symbol @ of the high-frequency current conducting path 1 a and Symbol @ of the high-frequency current conducting path 1 denote that the current of both the high-frequency current conducting paths have the same phase.
  • a magnetic repulsive force that is, a magnetic pressure acts on the surfaces of the steel strip.
  • a magnetic attracting force of the steel strip exceeds a magnetic repulsive force of the steel strip when an electric current is simply flowed through the high-frequency current conducting paths 1 a, 1 b, and the steel strip comes to be in an unstable state.
  • the magnetic repulsive force of the steel strip acts on the steel strip as if non-contact springs acted on the steel strip from both sides of the steel strip. Vibration of the steel strip is damped and bowing of the steel strip is straightened by the magnetic repulsive force. Under the condition that the vibration of the steel strip is damped and the bowing of the steel strip is straightened by the magnetic repulsive force, an excess metal attaching to the steel strip is removed from the steel strip and molten metal attaches uniformly to the surfaces of the steel strip.
  • a pair of high-frequency current conducting paths 1 a, 1 b are positioned near a steel strip S, facing the steel strip S, the steel strip being positioned between the high-frequency current conducting paths 1a, 1 b.
  • a high-frequency current I of the same phase is flowed through the current conducting paths 1 a, 1 b.
  • Figure 4 (A) is a side elevation showing another example of an apparatus for executing the method of the present invention.
  • Figure 5 (A) is a front elevation showing the apparatus as shown in Figure 4 (A).
  • Two pairs of high-frequency current conducting paths 1a, 1b, each facing the steel strip, a steel strip being positioned between the high-frequency current conducting paths 1 a, 1 b, are arranged above and below respectively.
  • the phase of the upper current conducting path is opposite to the phase of the lower current conducting path.
  • the phase of the upper current conducting path is equal to the phase of the lower current conducting path.
  • the phases of the upper and lower current conducting paths can be opposite or equal to the other.
  • Figure 6 (A) is a side elevation showing another example of the apparatus for executing the method of the present invention .
  • High-frequency current conducting paths 1 near both sides of a steel strip are arrranged, the steel strip being positioned between the High-frequency current conducting paths 1, without facing each other, being shifted upwardly and downwardly.
  • the high-frequency current conducting paths 1 as a whole are arranged in zigzag.
  • the high-frequency current conducting paths are arranged in such a way as shown in Figure 6 (A).
  • FIG. 7 is a side elevation showing another example of the apparatus for executing the method of the present invention.
  • High-frequency current conducting paths 1a, 1 excluding their sides facing the steel strip are enclosed by elecrtomagnetic material 2 having a high permeability and a high saturation magnetic flux density.
  • the inside of the electromagnetic material 2 is a water-cooled box 3. Due to a small magnetic resistance of the electromagnetic material 2, a magnetic field strong enough to saturate the steel strip can be effectively applied to the steel strip even by means of a comparatively small electric current, whereby a high magnetic pressure can be generated.
  • Figure 8 is a front elevation showing another example of the apparatus for executing the method of the present invention.
  • a bend 11 is formed at a portion of a high-frequency current conducting path 1 facing the edge of the steel strip along the direction of movement of the steel strip.
  • FIG. 9 is a front elevation showing another example of the apparatus for executing the method of the present invention.
  • Figure 10 is a side elevation showing the apparatus as shwon in Figure 9. The entire length of the high-frequency current conducting paths 1 a, 1 b near both sides of the steel strip are inclined in the width direction of the steel strip.
  • Figure 11 is an example showing the case where a portion of each of the high-frequency current conducting paths 1 a, 1 b is inclined in the width direction of the steel strip near the edges of the steel strip. It is applicable to each of the examples as shown in Figures 2 to 7 to incline the portions of the high-frequency current conducting paths near the edges of the steel strip.
  • the present inventors carried out a simulation analysis to calculate the magnetic pressure, on which the high-frequency current flowed through the high-frequency current conducting paths had an effect.
  • This analysis was carried out with an apparatus as shown in Figure 4 (A).
  • a coil having a section of 30 mm in thickness and 50 mm in width was used. Electric current of 3 x 10 4 A was flowed through the coil.
  • a steel strip of 2.3 mm in thickness which had a relative permeability of 1 was used.
  • Figure 12 is a graphical representation showing an analytic model. A relative position of a coil 51 and a steel strip 52 is shown in Figure 12.
  • the steel strip placed between high-frequency current conducting paths was positioned at the following levels:
  • Figure 13 is a graphical representation showing an example wherein one cycle of the maximum magnetic pressure is analyzed in the analysis model as shown in Figure 12.
  • Symbol A in the drawing indicates a state of the magnetic pressure in the saturation area.
  • Symbol B indicates a state of the magnetic pressure in the non-saturation area.
  • Symbol C is an avarage value of the magnetic pressures. A period of time, during which the magnetic attracting force exceeds the magnetic pressure, is 6% or less. The maximum value of the magnetic pressures is five times greater than the magnetic attracting force. Accordingly, notwithstanding that the steel strip is a ferromagnetic body, the magnetic pressure can be applied very stably to the steel strip.
  • Figure 14 (A) is a graphical representation showing a distribution of magnetic pressures in the case where the steel strip is centered between two high-frequency current conducting paths.
  • Figures 14 (B) and 14 (C) are graphical representations showing a distribution of magnetic pressures in the case where the steel strip is shifted by 5 mm and 10 mm respectively from the center between the two high-frequency current conducting paths toward the high-frequency current conducting path on one side. From the distribution of the magnetic pressures in Figures 14 (B) and 14 (C), it is understood that a force pushing the steel strip toward the center works as a whole in the case where the steel strip is shifted from the center.
  • This magnetic pressure is increased as the steel strip approaches the high-frequency current conducting path. In consequence, the magnetic pressure effectively acts on a centering work of the steel strip, which is effective in damping of vibration of the steel strip.
  • the magnetic pressure is effective in straightening of bowing of the steel strip. Owing to the magnetic pressure, a total amount of bowing of the steel strip can be limited to 0.5 mm or less.
  • the magnetic pressure as shown in Figure 14 (A) had the maximum value of 13452 Pa and this magnetic pressure was a pressure strong enough to wipe molten metal on the surface of the steel strip.
  • An apparatus corresponding to the examples in Figures 4 and 5 was installed 40 mm above the surface of a coating bath and coating weight on the steel strip was controlled on the basis of the above-mentioned results.
  • the width of the steel strip and the conditions of electric current were the same as those in the case of the aforementioned simulation analysis.
  • the line speed was 150 m/min.
  • the bowing of the steel strip at positions of wiping was completely straightened and vibration of the steel strip was limited to 5 mm or less according to the present invention. There were no splash and noise as in the case of using gas wiping nozzles.
  • the coating weight on the steel strip was controlled so that metal can attach very uniformly to the steel strip. It was confirmed that zincking of the steel strip wherein the coating weight on the steel strip was 35 g/m 2 , which had been hard to realize by means of the prior art wiping method, was easily carried out in the method of the present invention.
  • a method for controlling coating weight on a steel strip by using the prior art gas wiping nozzles can be applied to the above-described method of the present invention.
  • each of the high-frequency current conducting paths is arranged near one side of a steel strip and near another side of the steel strip drawn from a coating bath.
  • Each of the high-frequency current conducting paths is arranged in parallel with the steel strip above the surface of molten metal in the coating bath.
  • One high-frequency current conducting path near one side of the steel strip faces the other high-frequency current conducting path, the steel strip being positioned between the high-frequency current conducting paths.
  • North Pole and South Pole of a magnet are arranged outside the edges of the steel strip adjacent to the high-frequency current conducting paths, substantially facing each other and a width direction of the steel strip positioned between North Pole and South Pole of a magnet.
  • the steel strip is magnetically saturated by the magnet.
  • a high-frequency current of the same phase is flowed through the high-frequency current conducting paths and a high-frequency current of opposite phase is induced in the steel strip.
  • a magnetic pressure acting on the surfaces of the steel strip is generated by interaction of this induced high-frequency current with the high-frequency current of the high-frequency current conducting paths.
  • Bowing of the steel strip in the width direction of the steel strip and vibration of the steel strip are prevented by the magnetic pressure acting from both sides of the steel strip on the steel strip, and molten metal attaching to the steel strip is wiped out, whereby the coating weight on the steel strip is controlled.
  • Two pairs of high-frequency current conducting paths or more can be arranged at regular intervals in the direction of movement of a steel strip. Any magnet out of electromagnet and permanent magnet can be used.
  • the magnets are arranged substantially facing each other, the steel strip being positioned between the magnets.
  • the magnets can be arranged at two positions or more in the direction of movement of the steel strip.
  • Figure 15 is a side elevation showing an example of an apparatus for executing the method of the present invention.
  • Figure 16 is a front elevation showing the apparatus as shown in Figure 15.
  • a steel strip S is continuously drawn out of a coating bath 4.
  • Each of the high-frequency current conducting paths 1 a, 1 are arranged in parallel with each of the sides of the steel strip S near the steel strip and above the surface of molten metal in the coating bath.
  • North Pole and South Pole of a magnet 5 are positioned near the high-frequency current conducting paths 1 a, 1 b, substantially facing each other, a width direction of the steel strip being positioned between North Pole and South Pole of a magnet 5, outside both edges of the steel strip.
  • Both the high-frequency current conducting paths 1a, 1 near both sides of the steel strip are arranged at an upper position and a lower position in the height direction.
  • the magnets are arranged above and below the high-frequency current conducting paths 1 a, 1 b respectively.
  • the range of variation of magnetic field generated by the high-frequency current also comes to be present in the magnetically saturated area.
  • the steel strip undergoes only a repulsive force from the high-frequency current conducting paths by magnetically saturating a ferromagnetic body and causing the ferromagnetic body to be paramagnetic. In consequence, the unstable state due to the magnetic attracting force can be removed.
  • This repulsive force works like a non-contact spring. Vibration of the steel strip is restrained by the magnetic repulsive force and bowing of the steel strip is straightened.
  • Figure 17 is a side elevation showing an example of an apparatus for executing the method of the present invention.
  • Figure 18 is a front elevation showing the apparatus as shown in Figure 17.
  • North Pole and South Pole of a magnet are positioned between two pairs of high-frequency current conducting paths, out of which one is positioned above and the other below.
  • An electric current is flowed through the above two pairs of high-frequency current conducting paths as is in the examples of Figures 15 and 16.
  • Figure 19 is a side elevation showing an example of an apparatus for executing the method of the present invention.
  • Figure 20 is a front elevation showing the apparatus as shown in Figure 19.
  • high-frequency current conducting paths and magnets are arranged in such a manner as shown in Figures 15 and 16, but a magnet 5 is composed of electromagnets.
  • Each of the electromagnets is composed of a yoke 6 and a coil 7.
  • Figure 21 is a side elevation showing an example of an apparatus for executing the method of the present invention.
  • Figure 22 is a front elevation of the apparatus as shown in Figure 21.
  • Two pairs of high-frequency current conducting paths 1 a, 1 b, out of which one is positioned above and the other below, are arranged.
  • the magnets 5 are positioned between the upper and lower high-frequency current conducting paths.
  • bends 21 are formed along the direction of movement of the steel strip at positions where the high-frequency current conducting paths 1 a, 1 b face the edges of the steel strip.
  • the magnetic pressure inclines to weakening near the edges of the steel strip.
  • the high-frequency current conducting path is needed to incline relative to the entire length of the high-frequency current conducting path in the width direction of the steel strip as shown in Figures 9 and 10 or the high-frequency current conducting path can be inclined near the edges of the steel strip.
  • the present inventors carried out a simulation analysis to calculate the magnetic pressure acting on the steel strip under the influence of the high-frequency current flowed through the high-frequency current conducting path. Firstly, to confirm the fact that the steel strip was magnetically saturated by the electromagnet, a static magnetic field of the electromagnet and the steel strip in the structure of the apparatus as shown in Figures 19 and 20 was analyzed.
  • Figure 23 is a graphical representation showing an analytic model. In the drawing, a relative position of a steel strip 52 and an iron core 53 is indicated.
  • the analytic condition is as follows:
  • a distribution of magnetic fields obtained by the analysis is shown in Figure 24.
  • a magnetic field intensity in the ferromagnetic body indicated 6 x 10 5 A/m or more. This means that the steel strip is sufficiently magnetically saturated, that is, the steel strip fell in the saturation area.
  • a method for controlling the coating weight on a steel strip by using the prior art gas wiping nozzles can be applied to the above-described method of the present invention.
  • wiping nozzles are arranged near both edges of a steel strip drawn out of a coating bath.
  • High-frequency current conducting paths are positioned in the wiping nozzles. Gas is jetted on the steel strip drawn from the coating bath. A high-frequency current strong enough to magnetically saturate the steel strip is flowed through the high-frequency current conducting paths, and a high-frequency current of opposite phase is induced in the steel strip. A magnetic pressure acting on the surfaces of the steel strip is generated by interaction of this induced high-frequency current with the high-frequency current flowed through the high-frequency current conducting paths.
  • a coating weight on the steel strip is controlled by the magnetic pressure working from both sides of the steel strip and the gas jetted from the wiping nozzles. Further, bowing of the steel strip in the width direction of the steel strip and vibration of the steel strip are prevented by the magnetic pressure working from both sides of the steel strip.
  • two pairs of high-frequency current conducting paths or more can be arranged at regular intervals in the direction of movement of the steel strip. That is, two pairs of high-frequency current conducting paths or more can be positioned in the nozzles at regular intervals in the direction of movement of the steel strip. Separately from the nozzles, the high-frequency current conducting paths can be arranged above and below the nozzles.
  • a pair of the wiping nozzles, into which the high-frequency current conducting paths are included, are positioned, facing each other, the steel strip being positioned between the wiping nozzles.
  • a high-frequency current of the same phase is flowed through the facing high-frequency current conducting paths.
  • wiping nozzles In the case where a plurality of high-frequency current conducting paths are arranged near both sides of a steel strip, wiping nozzles, into which the high-frequency current conducting paths are included, need not face steel strip, the steel strip being positioned between the wiping nozzles.
  • the high-frequency current conducting paths can be arranged, being shifted in the direction of movement of the steel strip. In this case, there is no limit to the phase of electric current flowed through the high-frequency current conducting paths.
  • the high-frequency current conducting paths included into the nozzles are arranged in the width direction of the steel strip, but need not always be arranged in parallell with the width direction of the steel strip.
  • the entire length of the high-frequency current conducting path can be inclined relative to the width direction of the steel strip.
  • Parts of the high-frequency current conducting path can be inclined relative to the width direction of the steel strip. Since a direction of flow of electric current flowing through the steel strip near the edges of the steel strip forms an angle of 90 ° to a direction of flow of electric current flowing through the high-frequency current conducting path, a magnetic pressure near the edges of the steel strip inclines to weakening.
  • the entire length of the high-frequency current conducting path can be inclined relative to the width direction of the steel strip or the high-frequency current conducting path can be inclined near the edges of the steel strip.
  • the nozzles can be inclined. Only the high-frequency current conducting paths in the nozzles can be inclined.
  • Figure 25 is a side elevation showing an example of an apparatus for executing the method of the present invention.
  • Figure 26 is a front elevation of the apparatus as shown in Figure 25.
  • a steel strip is continuously drawn out of a coating bath 4.
  • Gas wiping nozzles 8 are arranged above the coating bath 4 near one side of the steel strip S and near another side of the steel strip S. Two gas wiping nozzles 8 face each other, the steel strip S being positioned between the gas wiping nozzles 8.
  • the gas wiping nozzles have high-frequency current conducting paths 1 a, 1 b at their ends.
  • Each of the high-frequency current conducting paths 1 a, 1 b is parallel with the surface of the steel strip.
  • two pairs of high-frequency current conducting paths are positioned above and below nozzle slit of each of the nozzles.
  • the magnetic repulsive force much prevails over the magnetic attracting force when the amplitude of the magnetic field exceeds a predetermined amplitude of the magnetic field.
  • a high-frequency current strong enough to magnetically saturate the steel strip is flowed through the high-frequency current conducting paths 1a, 1 b , and a necessary magnetic repulsive force can be obtained. Vibration of the steel strip is damped and bowing of the steel strip is straightened by the magnetic repulsive force of the steel strip.
  • Figure 27 is a side elevation showing another example of an apparatus for executing the method of the present invention.
  • Figure 28 is a front elevation showing the apparatus as shown in Figure 27.
  • High-frequency current conducting paths 1 a, 1 are included into each of tip nozzles in wiping nozzles 8 facing each other.
  • Other high-frequency current conducting paths 1a', 1 b' are arranged near both sides of a steel strip. In this example, phases of upper and lower high-frequency currents are opposite to each other, but they can have the same phase.
  • FIG. 29 is a side elevation showing another example of an apparatus for executing the method of the present invention.
  • High-frequency current conducting paths 1a, 1 are included into wiping nozzles 8.
  • the wiping nozzles 8 near both sides of a steel strip do not face each other, the steel strip being positioned between the wiping nozzles 8, but the wiping nozzles 8 are arranged, being shifted above and below.
  • Other high-frequency current conducting paths 1 a', 1 b' are arranged above and below each of the wiping nozzles 8.
  • the high-frequency current conducting paths are arranged in zigzag. An electric current of phase opposite to the high-frequency current flows through the steel strip in response to high-frequency current of each of the high-frequency current conducting paths.
  • a magnetic pressure acts on the steel strip S alternately from opposite sides in the direction of movement of the steel strip.
  • the phases of the electric current flowing through the high-frequency current conducting paths are opposite to each other near one side of the steel strip and near the other side of the steel strip, the phases of the electric current can be the same. That is, the phases of the electric current flowing through the high-frequency current conducting paths are optional.
  • the high-frequency current conducting path can be inclined relative to the entire length of high-frequency current conducting path in the width direction of the steel strip or the high-frequency current conducting path can be inclined near the edges of the steel strip.
  • the high-frequency current conducting path can be inclined relative to the entire length of the high-frequency current conducting path as shown in Figures 9 and 10 or the high-frequency current conducting path can be inclined near the edges of the steel strip.
  • An apparatus corresponding to the apparatus as shown in Figures 27 and 28 was installed at 400 mm above a coating bath on the basis of the above-mentioned result, and coating weight on a hot-dipping steel strip was controlled.
  • the width of the steel strip and the condition of electric current were the same as those of the above simulation analysis.
  • the line speed was 150 m/min.
  • the flow speed of gas was 190 m/s.
  • the bowing of the steel strip at the positions of wiping was perfectly straightened by the present invention.
  • the vibration of the steel strip was restrained within the range of 1 mm or less.

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  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Coating With Molten Metal (AREA)

Claims (16)

1. Verfahren zum Kontrollieren des Beschichtungsgewichtes eines heißmetallisierten Stahlbandes, umfassend die nachfolgenden Schritte:
Positionieren von mindestens einem Paar von Hochfrequenzstromleitpfaden (1 a, 1b) in der Nähe einer Seite eines Stahlbandes (S) und in der Nähe einer anderen Seite des aus einem Beschichtungsbad (4) herausgezogenem Stahlbandes, wobei sich jeder der Hochfrequenzstromleitpfade parallel zu einer Oberfläche des Stahlbandes über dem Beschichtungsbad befindet; und
Leiten eines Hochfrequenzstromes von mindestens 500 Hz, der stark genug ist, das Stahlband magnetisch zu sättigen, durch das mindestens eine Paar von Hochfrequenzstromleitpfaden, um einen Hochfrequenzstrom von einer entgegengesetzten Phase in dem Stahlband zu induzieren, wobei ein durch Wechselwirkung des induzierten Hochfrequenzstromes mit einem Hochfrequenzstrom der Hochfrequenzstromleitpfade erzeugter magnetischer Druck auf Oberflächen des Stahlbandes wirkt.
2. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, daß
das Positionieren von mindestens einem Paar von Hochfrequenzstromleitpfaden ein Positionieren von mindestens einem Paar von Hochfrequenzstromleitpfaden beinhaltet, so daß sich die Hochfrequenzstromleitpfade über das Stahlband hinweg einander gegenüberliegen können; und das Hindurchleiten eines Hochfrequenzstromes das Leiten eines Hochfrequenzstromes von gleicher Phase durch mindestens ein Paar von Hochfrequenzstromleitpfaden beinhaltet.
3. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, daß
das Positionieren von mindestens einem Paar von Hochfrequenzstromleitpfaden ein Anordnen von mindestens zwei Paaren von Hochfrequenzstromleitpfaden beinhaltet, so daß jeder der Hochfrequenzstromleitpfade relativ zu einem Stahlband nach oben und unten verschoben positioniert werden kann.
4. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, daß
der Hochfrequenzstromleitpfad, außer seine einem Stahlband gegenüberliegende Seite, von einem elektromagnetischen Material (2) umschlossen ist.
5. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, daß
der Hochfrequenzstromleitpfad eine Biegung (11) besitzt entlang einer Bewegungsrichtung eines Stahlbandes an einem Abschnitt bei dem der Hochfrequenzstromleitpfad einem Rand des Stahlbandes gegenüberliegt.
6. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, daß
der Hochfrequenzstromleitpfad über seine gesamte Länge in einer Breitenrichtung des Stahlbandes geneigt ist.
7. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, daß
ein Abschnitt des Hochfrequenzstromleitpfades bei dem der Hochfrequenzstromleitpfad einem Rand eines Stahlbandes gegenüberliegt, in einer Breitenrichtung des Stahlbandes geneigt ist.
8. Verfahren nach Anspruch 2,
gekennzeichnet durch
folgenden Schritt:
Anordnen von Nordpol und Südpol von mindestens einem Magneten (5), so daß Nordpol und Südpol des Magneten einander gegenüberliegen können, wobei eine Breitenrichtung des Stahlbandes zwischen dem Nordpol und dem Südpol des Magneten außerhalb beider Ränder des Stahlbandes in der Nähe mindestens eines Paares von Hochfrequenzstromleitpfaden positioniert ist, und das Stahlband durch den Magneten magnetisch gesättigt ist.
9. Verfahren nach Anspruch 8,
dadurch gekennzeichnet, daß
die Hochfrequenzstromleitpfade zwei Paare von in einer Höhenrichtung angeordneten Hochfrequenzstromleitpfaden sind, wobei ein Paar der Hochfrequenzstromleitpfade ein Paar oberer Hochfrequenzstromleitpfade und das andere ein Paar unterer Hochfrequenzstromleitpfade ist; und die Magneten zwei Magneten sind, wobei ein Magnet in der Nähe eines oberen Abschnittes der oberen Hochfrequenzstromleitpfade und der andere in der Nähe eines unteren Abschnittes der unteren Hochfrequenzstromleitpfade positioniert ist.
10. Verfahren nach Anspruch 8,
dadurch gekennzeichnet, daß
die Hochfrequenzstromleitpfade zwei Paare von in einer Höhenrichtung angeordneten Hochfrequenzstromleitpfaden sind, wobei ein Paar von den Hochfrequenzstromleitpfaden ein oberes Paar von Hochfrequenzstromleitpfaden und das andere ein unteres Paar von Hochfrequenzstromleitpfaden ist; und
der Magnet ein zwischen dem oberen Hochfrequenzstromleitpfad und dem unteren Hochfrequenzleitpfad in einer Höhenrichtung angeordneter Magnet ist.
11. Verfahren nach Anspruch 8,
dadurch gekennzeichnet, daß
der Magnet ein Elektromagnet ist.
12. Verfahren nach Anspruch 8,
dadurch gekennzeichnet, daß
daß der Magnet ein Permanentmagnet ist.
13. Verfahren nach Anspruch 1,
gekennzeichnet durch
folgende weitere Schritte:
Positionieren von Abstreifdüsen in der Nähe beider Seiten eines aus dem Beschichtungsbad herausgezogenen Stahlbandes; und
Ausstoßen von Gas von den Abstreifdüsen auf das aus dem Beschichtungsbad herausgezogene Stahlband.
14. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, daß
das Positionieren von mindestens einem Paar von Hochfrequenzstromleitpfaden das Positionieren von Hochfrequenzstromleitpfaden in diesen Abschnitten der Abstreifdüsen beinhaltet.
15. Verfahren zum Kontrollieren des Beschichtungsgewichtes eines heißmetallisierten Stahlbandes, umfassend die nachfolgenden Schritte:
Positionieren von Hochfrequenzstromleitpfaden (1 a, 1b) in der Nähe einer Seite eines aus einem Beschichtungsbad (4) herausgezogenen Stahlbandes (5) und in der Nähe der anderen Seite des Stahlbandes, wobei sich jeder der Hochfrequenzstromleitpfade parallel zu einer Oberfläche des Stahlbandes über dem Beschichtungsbad befindet, und wobei ein Hochfrequenzstromleitpfad in der Nähe einer Seite des Stahlbandes einem in der Nähe einer anderen Seite des Stahlbandes befindlichen Hochfrequenzstromleitpfades gegenüberliegt, und das Stahlband zwischen den beiden Hochfrequenzstromleitpfaden positioniert ist;
Anordnen von Nordpol und Südpol eines Magneten (5) außerhalb beider Ränder des Stahlbandes in der Nähe der Hochfrequenzstromleitpfade, so daß Nordpol und Südpol des Magneten einander gegenüberliegen können, wobei eine Breitenrichtung eines Stahlbandes zwischen Nordpol und Südpol des außerhalb beider Ränder des Stahlbandes in der Nähe mindestens eines Paares von Hochfrequenzstromleitpfaden befindlichen Magneten positioniert ist; und
Leiten eines Hochfrequenzstromes von mindestens 500 Hz und von gleicher Phase durch die Hochfrequenzstromleitpfade, um einen Hochfrequenzstrom von entgegengesetzter Phase zu induzieren, wobei ein durch Wechselwirkung dieses induzierten Hochfrequenzstromes mit dem Hochfrequenzstrom der Hochfrequenzstromleitpfade erzeugter magnetischer Druck auf Oberflächen des Stahlbandes wirkt.
16. Verfahren zum Kontrollieren des Beschichtungsgewichtes eines heißmetallisierten Stahlbandes, umfassend die nachfolgenden Schritte:
Positionieren von Abstreifdüsen (8) in der Nähe beider Seiten eines aus einem Beschichtungsbad (4) herausgezogenen Stahlbandes (S);
Anordnen von Hochfrequenzstromleitpfaden (1 a, 1b) in Abstreifdüsen, wobei jeder der Hochfrequenzstromleitpfade parallel zu jeder der Oberflächen des Stahlbandes über dem Beschichtungsbad ist;
Ausstoßen von Gas von den Abstreifdüsen auf das aus dem Beschichtungsbad herausgezogene Stahlband; und
Leiten eines Hochfrequenzstromes von mindestens 500 Hz, der stark genug ist, das Stahlband magnetisch zu sättigen, durch die Hochfrequenzstromleitpfade, um einen Hochfrequenzstrom von entgegengesetzter Phase in dem Stahlband zu induzieren, wobei ein durch Wechselwirkung dieses induzierten hochfrequenten Stromes mit einem Hochfrequenzstrom der Hochfrequenzstromleitpfade erzeugter magnetischer Druck auf Oberflächen des Stahlbandes wirkt.
EP92110677A 1991-06-25 1992-06-25 Methode zum Kontrollieren des Beschichtungsgewichts eines heissmetallisierten Stahlbandes Expired - Lifetime EP0525387B1 (de)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP3180420A JP2601068B2 (ja) 1991-06-25 1991-06-25 溶融めっき鋼板の目付方法
JP3180418A JP2601067B2 (ja) 1991-06-25 1991-06-25 溶融めっき鋼板の目付方法
JP180418/91 1991-06-25
JP180420/91 1991-06-25
JP238762/91 1991-08-26
JP3238762A JP2556220B2 (ja) 1991-08-26 1991-08-26 溶融めっき鋼板の目付方法

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EP0525387B1 true EP0525387B1 (de) 1995-02-22

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BE1008252A6 (fr) * 1994-05-02 1996-02-27 Centre Rech Metallurgique Procede de fabrication d'une bande d'acier revetue de zinc par immersion.
FR2754545B1 (fr) * 1996-10-10 1998-12-11 Maubeuge Fer Procede et dispositif d'essorage d'une bande metallique revetue en continu ou trempe
JP2004027315A (ja) * 2002-06-27 2004-01-29 Jfe Steel Kk 溶融金属めっき鋼板の製造方法および製造装置
SE528663C2 (sv) * 2005-06-03 2007-01-16 Abb Ab En anordning och ett förfarande för att belägga ett långsträckt metalliskt element med ett skikt av metall
SE529060C2 (sv) * 2005-06-30 2007-04-24 Abb Ab Anordning samt förfarande för tjockleksstyrning
ITMI20071166A1 (it) * 2007-06-08 2008-12-09 Danieli Off Mecc Metodo e dispositivo per il controllo dello spessore di rivestimento di un prodotto metallico piano
ITMI20071164A1 (it) * 2007-06-08 2008-12-09 Danieli Off Mecc Metodo e dispositivo per il controllo dello spessore di rivestimento di un prodotto metallico piano
US11162166B2 (en) 2017-02-24 2021-11-02 Jfe Steel Corporation Apparatus for continuous molten metal coating treatment and method for molten metal coating treatment using same

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FR2521797B1 (fr) * 1982-02-18 1985-12-06 Cem Comp Electro Mec Procede et dispositifs pour minimiser la puissance induite dans un produit plat conducteur maintenu electromagnetiquement sans contact

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* Cited by examiner, † Cited by third party
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CN101720361B (zh) * 2007-06-08 2012-03-21 丹尼尔和科菲森梅克尼齐有限公司 用于控制平的金属制品上的涂层厚度的方法和装置

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KR950000007B1 (ko) 1995-01-07
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DE69201466D1 (de) 1995-03-30
KR930000706A (ko) 1993-01-15

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