JP3302280B2 - Hot-dip metal plating apparatus and hot-dip metal plating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-dip metal plating apparatus and a hot-dip metal plating method, and more particularly to a hot-dip metal plating bath in which a steel sheet is introduced through an opening provided at the bottom of the hot-dip metal bath. The present invention relates to a hot-dip metal plating apparatus and a hot-dip metal plating method for a steel sheet that performs plating while holding a plating bath by applying a magnetic field to the bath.

[0002]

2. Description of the Related Art Hot-dip metal-plated steel sheets use Zn, Al, Pb, Sn and the like as molten metal, and are widely used for automobiles, building materials, home appliances and cans. Here, as an example of a hot-dip galvanized steel sheet, a general method of manufacturing a hot-dip galvanized steel sheet using Zn will be described. The surface of the cold-rolled steel sheet is washed in a pretreatment step, heated and annealed in a non-oxidizing or reducing atmosphere, and then cooled without oxidizing the steel sheet to a temperature suitable for plating, and then cooled in a plating bath. Immersed continuously. Then, after changing the direction of the steel sheet in the vertical direction with a roll (sink roll etc.) immersed in the bath, the steel sheet is pulled up from the plating bath, and excess zinc adhering to the steel sheet surface is removed by an adhesion amount adjusting device such as gas wiping. Remove, adjust the amount of adhesion, and cool.

[0003] However, in the above method, the plating bath becomes extremely large because bath equipment such as a sink roll is present.
The flexibility is small when changing the plating solution type, etc.
Sink roll maintenance is complicated, or dross bites between the sink roll and the steel plate to be plated,
There were problems such as the occurrence of quality defects such as surface flaws.

Therefore, various plating methods without using in-bath equipment such as sink rolls have been proposed, and a so-called air pot method has been proposed as a method capable of stably plating both surfaces of a steel sheet. As shown in FIG. 3, a plating bath having an opening at the bottom and holding a plating bath is provided, and a steel plate is intruded from the opening and pulled up to perform plating.

An important point of the plating method of the aerial pot method is to prevent the plating bath from leaking from the opening, and various methods utilizing the action of electromagnetic force have been proposed. For example, JP-A-63-310949 discloses that
A method for holding molten metal with a linear motor, and Japanese Patent Application Laid-Open No. 5-86446, a method for holding molten metal by using an electromagnetic force by the action of a moving magnetic field and an electromagnetic force by the action of a high-frequency magnetic field, Further, Japanese Patent Application Laid-Open No. 63-303045 proposes a method in which a molten metal is held by the interaction of a magnetic field and an electric current, and a gas is injected to seal a steel sheet introduction portion.

[0006] However, in the above-described method of providing a steel sheet through the opening, and pulling the steel sheet upward through the opening and using the electromagnetic force to hold the plating bath, the steel sheet is significantly meandering or vibrated. In an unsteady state, the steel sheet may not be able to pass through the opening or may be damaged by contacting the opening side wall or the plating bath,
There is a problem that maintenance work such as replacement of the opening or the plating bath increases.

In such a case, it is conceivable to control the position of the plating bath in accordance with the passing position of the steel sheet so that the steel sheet can always pass through the center of the opening. However, it requires considerable capital investment and is not economical. In addition, when the plating bath moves during the plating operation, the plating bath vibrates and the action of the electromagnetic force is temporarily insufficient, and the plating solution leaks from the opening. When the plating solution leaks, the plating solution is applied to a deflector roll, a steel plate shape correction roll (support roll), a steel plate vibration prevention roll (guide roll), etc. of the steel plate supporting device disposed on the steel plate pass line in the vertical direction of the opening. Adheres, and the adhered plating solution is picked up by the steel sheet, resulting in a quality defect. In order to prevent such a quality defect, it was necessary to frequently perform maintenance such as cleaning of the roll or replacement of the roll.

[0008] As described above, it is still difficult to perform a smooth plating operation during an unsteady state in which the steel sheet remarkably meanders and the steel sheet vibrates remarkably, and a new means different from a stable continuous operation is demanded. It had been.

[0009]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has been made in view of the above circumstances. It is an object of the present invention to provide a hot-dip metal plating apparatus and a hot-dip metal plating method that prevent the occurrence of plating and enable stable plating operations.

[0010]

According to the present invention, there is provided a plating bath for injecting a steel plate from an opening provided in a bottom portion, pulling the steel plate upward and plating the steel plate, and providing a predetermined interval on both sides with the steel plate interposed therebetween. A magnetic field applying means, and applying a magnetic field to the plating bath in the plating bath, and an electromagnetic sealing device for holding the plating bath, wherein the plating bath is disposed on both sides of the steel plate. A molten metal plating apparatus for a steel sheet, wherein the apparatus is configured to be divided into two half tubs, and the half tubs are respectively provided with moving means so as to advance and retreat with respect to the steel sheet.

Further, in the present invention, it is preferable that the magnetic field applying means of the electromagnetic sealing device is provided so as to be movable with respect to the steel sheet with moving means on both sides of the steel sheet. Further, in the present invention, a steel plate shape measuring device and a shape determining device that receives a signal from the steel plate shape measuring device and determines an abnormality of the steel plate shape may be installed upstream of the opening.

[0012] The present invention also provides a plating bath having a magnetic field applying means disposed at predetermined intervals on both sides of the steel plate, with the steel plate being inserted from an opening provided at the bottom of the plating bath and pulled up. A magnetic field is applied to the plating bath inside to hold the plating bath, the plating solution is supplied to the lower part of the plating bath through a plating solution supply passage, and the plating solution is discharged from the upper part of the plating bath through a plating solution discharge passage. In the hot-dip metal plating method for a steel sheet to be plated, the plating bath is a plating bath that can be divided into two half baths on both sides of the steel plate, and the half bath and the magnetic field applying unit are moved forward and backward with respect to the steel plate. Arranged freely, measure the shape of the steel plate online on the upstream side of the opening, and when the measured value exceeds a predetermined allowable value, stop supplying the plating solution. Then After discharging the plating solution in the plating bath, the a semi-tub or even molten metal plating method of the steel sheet, characterized in that for moving the magnetic field applying means.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the configuration of a hot-dip metal plating apparatus of the present invention will be described. FIG. 1 shows a hot-dip metal plating apparatus according to one embodiment of the present invention. The hot-dip metal plating apparatus 6 of the present invention includes a plating bath 1 having an opening 3 at the bottom,
And an electromagnetic sealing device 2 that generates an electromagnetic force and holds the plating bath.

In the present invention, the shape of the plating bath 1 is not particularly limited. However, as shown in FIG. 1, the plating bath 1 preferably has a protruding portion 8 protruding downward along the steel plate.
A slit-shaped opening is provided at the bottom of the protruding portion, and the steel plate passes through substantially the center of the protruding portion 8. The shape of the opening is not particularly limited as long as the steel plate as the material to be plated can pass therethrough. Further, it is preferable that the gap between the openings is as narrow as possible because the leakage amount of the plating bath can be suppressed. However, it is limited by the shape of the steel sheet, and is preferably 10 to 50 mm.

[0015] The protrusion is long in the width direction of the steel sheet.
The horizontal cross section is a rectangular steel plate passage, and the steel plate penetrates into the plating bath along the protrusion from below through the opening.
In the plating bath 1, a plating solution is supplied from the auxiliary bath to both sides of the steel plate. As shown in FIG. 2, the plating bathtub 1 of the present invention has two half bathtubs 1a, 1a on both sides of a steel plate.
a. The divided half baths 1a, 1a are provided with moving means 5a, 5a, respectively, so that they can move forward and backward with respect to the steel plate. Although the moving means is not particularly limited, an air cylinder, a hydraulic cylinder, a worm gear, or the like is preferable.

In the present invention, the electromagnetic sealing device 2 may be any device that can hold the plating bath at the opening 3, and any conventionally known electromagnetic force generating device can be applied. It is preferable that magnetic field applying means (electromagnetic cores) 2a, 2a are provided at predetermined intervals along the protrusion 8 on both sides of the opening of the plating bath 1 to generate a horizontal magnetic field or a moving magnetic field. The plating bath in the plating bath is held in the plating bath without leaking downward from the opening 3 by the electromagnetic force due to the interaction between the magnetic field and the induced current flowing in the plating bath.

As a means for applying a horizontal magnetic field, an electromagnetic force generator using a high frequency (high-frequency electromagnetic application device) is preferable. This high-frequency electromagnetic application device preferably has a frequency in the range of 1 to 10 kHz. Further, instead of the horizontal magnetic field, a moving magnetic field applying device may be provided on the projecting portion. The moving magnetic field applying device preferably has a frequency range of 10 to 1000 Hz.

Further, according to the present invention, the magnetic field applying means 2a, 2a arranged at predetermined intervals on both sides of the steel plate.
Are provided with moving means 5b, 5b, respectively, so that they can move forward and backward with respect to the steel plate. The moving means is not particularly limited, but an air cylinder, a hydraulic cylinder, a worm gear or the like is preferable. The magnetic field applying means 2a may be fixed to the plating bath or may be independently movable. When the half bath 1a and the magnetic field applying means 2a are independently movably installed, it goes without saying that the moving means is independently provided.

On the inlet side of the hot-dip metal plating apparatus of the present invention,
A steel plate supporting device 30 is provided as in the conventional device. The steel sheet support device 30 guides the steel sheet annealed in an annealing furnace in a non-oxidizing or reducing atmosphere to a plating bath without being oxidized. The steel sheet S annealed in the annealing furnace is a deflector roll
The support roll 32 is turned in the vertical direction by 33
And the guide roll 31 suppresses the vibration. Next, the steel sheet S is guided to a hot-dip metal plating apparatus, and is continuously plated.

In the present invention, it is preferable to install a steel plate shape measuring device 51 upstream of the opening of the plating bath. The steel plate shape measuring device measures the warp (C warp, W warp) of the steel plate, the vibration of the steel plate, and the amount of meandering of the steel plate. It is preferable to measure the warpage of the steel sheet by installing the steel sheet warpage measuring device 51b in several places in the width direction of the steel sheet or as a scanning type. It is preferable to use an infrared laser distance meter as the steel plate warpage measuring device 51b. The measurement position is
The measurement is preferably performed immediately above the support roll 32 of the steel plate supporting device 30. The vibration of the steel plate is measured by the steel plate vibration measuring device 51a. It is preferable that the steel plate vibration measuring device 51a uses an infrared laser distance meter. The measurement position is preferably located immediately above the guide roll 31 of the steel plate support device 30. The meandering amount of the steel plate is measured by the meandering amount measuring device 51c. It is preferable that the steel plate meandering amount measuring device 51c uses a steel plate position detector. The measurement position is not particularly limited, but is preferably directly above the deflector roll 33.

Further, it is preferable to provide a shape judging device 52 for inputting a signal from the steel plate shape measuring device 51 and judging an abnormality of the steel plate shape. When each measured value measured by the steel plate shape measuring device 51 exceeds a preset allowable value, an abnormal signal is generated from the shape determining device. In this way, measures are taken to avoid accidents such as the steel plate coming into contact with the side wall of the opening of the plating bath. The preset allowable value is, for example, a position 10 mm inside the outer edge of the opening of the plating bath. When the steel plate passes outside this position, the risk of contact with the opening side wall increases.

In the present invention, when the steel sheet is significantly meandering,
Or, in an unsteady state such as when the vibration of the steel sheet is remarkable, in order to prevent the steel sheet from coming into contact with the side wall of the opening of the plating bath, the information from the steel sheet shape measuring device described above is used to change the plating bath and the magnetic field applying means. Retreat from the passage area. On the exit side of the hot-dip metal plating apparatus of the present invention, usually,
An adhesion amount adjusting device 20 is provided. The adhesion amount adjusting device 20,
It is preferable to use a gas wiping nozzle for blowing high-pressure gas, which is for squeezing out the plating solution excessively attached to the steel sheet.

It is preferable that the molten metal plating bath 1 is provided with a plating solution supply device 10 having one or more auxiliary baths 13. The plating solution supply device 10 includes one or more auxiliary baths 13 and a plating solution supply passage 12, a plating solution discharge passage 11, and a piping switching device 15. The plating solution supply device 10 is preferably located as close to the plating bath as possible to facilitate supply of the plating solution to the molten metal plating bath or discharge of the plating solution from the plating bath. The plating solution supply passage 12 is a closed type passage connecting the plating bath and the auxiliary bath, and continuously supplies the plating solution into the plating bath at the start of plating. The plating solution discharge passage 11 is a discharge passage for transferring excess plating solution discharged from the plating bath during the plating operation, and is a passage for guiding the plating solution to the auxiliary bath.
Also, at the end of plating, part of the plating solution that could not be discharged from the plating bath discharge passage and remained in the plating bath tub was released from the plating solution supply passage 12 by releasing the sealing of the plating solution supply passage, and was discharged out of the plating bath bath. The remaining part is removed by attaching to a continuously transported steel sheet and taking it out.

The method of supplying the plating solution from the auxiliary bath 13 to the plating bath and the method of discharging the plating solution from the plating bath 1 to the auxiliary bath 13 are not particularly limited. For example, as shown in FIG. The solution supply passage side is provided with a pump P to supply from the lower part of the plating bath, and the plating solution discharge passage side is discharged from the upper part of the plating bath by overflow, and is forcibly discharged by a method of being dropped by gravity and transferred to the auxiliary bath or by a pump. The method is preferred. Further, a header may be provided in the plating bath in connection with the plating solution supply passage. By providing the header, the supply of the plating solution to the steel sheet becomes uniform. Further, a plating solution discharge passage may be provided in connection with the header.

In the present invention, the plating bath is a plating bath which can be divided into two half baths on both sides of the steel plate, and the half bath and the magnetic field applying means are arranged to be able to advance and retreat with respect to the steel plate. Using the device described above,
The shape of the steel sheet is measured online by a steel sheet shape measuring device upstream of the opening, and when the measured value exceeds a predetermined allowable value, the steel sheet speed is immediately reduced to a low speed (preferably 30 to 50 mpm). Then, the supply of the plating solution to the plating bath is stopped, and after the plating solution in the plating bath is discharged, the half bath or the magnetic field applying means is moved.

In the semi-tub, the distance between the steel plate surface and the side wall of the opening is limited.
It is only necessary to be able to move so as to be 50 mm or more, and even if a normal steel plate shape defect occurs, contact between the steel plate and the side wall of the opening can be avoided. In addition, if it can be moved by 150 mm or more, the contact between the steel plate and the side wall of the opening can be avoided in any unsteady state, and an accident such as damage to the opening can be prevented.

The magnetic field applying means is installed adjacent to the plating bath. However, it is not necessary to move the half bath if there is no hindrance. It is preferable to move with the bathtub or independently. The structure that can be moved integrally with the half bathtub makes the equipment simple. After moving the semi-tub, the magnetic field applying means, observe the steel plate shape, perform work such as correcting the steel plate shape, correcting the steel plate passing position, and confirm that the steel plate passes the predetermined position, The magnetic field applying means is moved to a predetermined position, and while applying a magnetic field, the plating solution is supplied into the plating bath to resume the normal plating operation.
If the shape of the steel sheet is extremely poor, the steel sheet may be stopped and corrected.

[0028]

EXAMPLE A hot-dip galvanizing was applied to an ultra-low carbon steel sheet using a hot-dip metal plating apparatus shown in FIG. The plating bath tub 1 used is configured so as to be dividable into half tubs, and the divided half tubs have moving means 5 each composed of an air cylinder.
a, 5a are attached, and the structure is capable of retracting up to 300 mm from the steel plate. The magnetic field applying means 2a is fixedly installed in the plating bath. Further, a steel plate shape measuring device 51 is installed in the steel plate supporting device 30. Further, a signal from the steel plate shape measuring device 51 can be input to the shape determining device.

Although not shown in FIG. 1, the steel sheet to be plated is cleaned in a normal pretreatment step, and then annealed in an annealing step. The shape was corrected, and it entered the plating bath 1 through the opening 3 at the bottom to be plated. The amount of the steel plate plated on the surface was adjusted by the adhesion amount adjusting device 20, and the steel plate was cooled. The operating conditions are shown below.

Steel type: ultra-low carbon steel Steel plate size: 1200mm width, 1.0mm thickness Steel plate speed: 130mpm Plating solution composition: Zn + 0.2% Al Plating bath temperature: 475 ° C Steel plate temperature immediately before plating: 480 ° C Plating bath supply: 400 l / min Maximum plating bath height in the plating bath: 200 mm Coating weight: 45 g / m ^{2 on} one side (using N ₂ gas) AC current frequency of the magnetic field applying device: 2 kHz Magnetic flux density between magnetic field applying device cores: 0.5 T Plating operation In the meantime, when the measured value of the steel plate shape measuring device 51 exceeds the allowable value as a preset allowable value within 10 mm inside the outer edge of the opening 3 of the plating bath 1, an abnormal signal from the shape determining device Generated.

Upon occurrence of the abnormal signal, the steel sheet speed is immediately reduced.
The speed was set to 40 mpm, the supply of plating solution to the plating bath was stopped, and the plating solution in the plating bath was discharged.
Each half bath and the magnetic field applying means were retracted by 60 mm from the steel plate. Observe the steel plate shape, correct the steel plate shape, correct the steel plate passing position, confirm that the steel plate passes the predetermined position, move the half bath, magnetic field applying means to the predetermined position, apply the magnetic field The plating solution was supplied into the plating bath while the normal plating operation was resumed. Thereby, contact between the steel plate and the side wall of the opening can be avoided, and an accident such as breakage of the opening can be prevented.

In the above description, only an example of hot-dip galvanizing on a steel sheet has been described. However, this is not to be construed as limiting the present invention to other metals such as molten metals such as Zn, Al, Pb, Sb, and Mg and alloys thereof. It goes without saying that the present invention can be applied to hot-dip metal plating. Further, it does not prevent the alloying by the heat treatment after the adjustment of the adhesion amount.

[0033]

According to the present invention, in a hot-dip metal plating method for pulling up a steel sheet from an opening at the bottom of a plating bath and performing plating, even if an unsteady state such as meandering or vibration of the steel sheet occurs, the opening of the opening is not affected. A stable plating operation can be continued without causing damage or the like. Further, the effect of reducing the maintenance and inspection work can be expected.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of the device of the present invention.

FIG. 2 is a schematic sectional view showing one embodiment of the device of the present invention.

FIG. 3 is a conceptual diagram showing an example of a conventional hot-dip metal plating apparatus.

[Explanation of symbols]

 Reference Signs List 1 plating bath 1a half bath 2 electromagnetic sealing device 2a magnetic field applying means 3 opening 5, 5a, 5b moving means 6 molten metal plating device 7 plating bath 10 plating solution supply device 11 plating solution discharge passage 12 plating solution supply passage 13 auxiliary bath 15 Pipe switching device 20 Adhesion amount adjusting device 30 Steel plate supporting device 31 Guide roll 32 Support roll 33 Deflector roll 50 Annealing furnace 51 Steel plate shape measuring device 51a Steel plate vibration measuring device (infrared laser distance meter) 51b Steel plate warping measuring device (infrared laser distance) Meter) 51c steel sheet meandering meter (steel sheet position detector) S steel sheet P pump

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshitane Matsukawa 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Inside the Chiba Works of Kawasaki Steel Works (72) Inventor Kazumasa Mihara 4-6 Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima No.22 Mitsubishi Heavy Industries, Ltd.Hiroshima Works (72) Inventor Kenichi Unoki 4-62 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd.Hiroshima Research Institute (56) References JP-A-8-337856 (JP, A) JP-A-7-3415 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 2/00-2/40

Claims (4)

(57) [Claims] 1. A plating bath for injecting a steel plate from an opening provided in a bottom portion, pulling the steel plate upward, and plating the steel plate;
In a hot-dip metal plating apparatus comprising: a magnetic field applying means disposed at predetermined intervals on both sides of the steel sheet, and a magnetic field applied to a plating bath in the plating bath to hold the plating bath; The plating bath is configured to be splittable into two half-tubs on both sides with the steel plate interposed therebetween, and the half-tubs are respectively provided with moving means and arranged so as to be able to advance and retreat with respect to the steel plate. Hot-dip metal plating equipment. 2. A magnetic field applying means of the electromagnetic sealing device,
The hot-dip metal plating apparatus for a steel sheet according to claim 1, wherein the steel sheet is provided with moving means on both sides of the steel sheet so as to be able to move forward and backward with respect to the steel sheet. 3. A steel plate shape measuring device and a shape judging device for inputting a signal from the steel plate shape measuring device and judging an abnormality of the steel plate shape are installed upstream of the opening. Item 3. A hot-dip metal plating apparatus for a steel sheet according to item 1 or 2. 4. A plating bath in the plating bath, wherein a steel plate enters through an opening provided at the bottom of the plating bath and is lifted upward, and a magnetic field applying means is arranged at predetermined intervals on both sides of the steel plate. A steel sheet to be plated while applying a magnetic field to the plating bath to supply a plating solution to a lower portion of the plating bath through a plating solution supply passage and discharging the plating solution from a top of the plating bath through a plating solution discharge passage. In the hot-dip metal plating method, the plating bath is a plating bath which can be divided into two half baths on both sides of the steel plate, and the half bath and the magnetic field applying means are arranged to be able to advance and retreat with respect to the steel plate. Then, the shape of the steel plate is measured online on the upstream side of the opening, and when the measured value exceeds a predetermined allowable value, the supply of the plating solution is stopped, and then the plating is performed. A method for hot-dip plating a steel sheet, comprising: moving the half bath or the magnetic field applying means after discharging the plating solution from the bath.