JP2650248B2 - Continuous metal plating equipment for steel sheets - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for continuously plating a steel sheet surface without using a molten metal bath.

[Conventional technology]

Conventionally, as a method of forming a plating film on the surface of a steel sheet, a hot-dip plating method of dipping a steel sheet in a hot-dip metal is widely performed.

This method can be divided into several processes depending on the method of pre-treating the surface of the steel sheet before plating, but the basics of the plating process are all common.

As an example, a continuous galvanizing line (CGL) for continuously plating a steel strip will be described.

Fig. 3 shows an example of CGL. (1) is a direct-fired heating furnace that burns off oil and dirt on the steel strip surface and heats the steel strip to a predetermined temperature, and (2) oxidizes the steel strip surface. A reduction furnace for reducing the film with hydrogen in the atmosphere and performing annealing, (3)
Is a cooling furnace for cooling the steel strip according to a predetermined heat cycle.

The steel strip (9), which has been pretreated and cleaned in the pretreatment furnaces (1) to (3), is immersed in a hot-dip zinc bath (4), and a hot-dip galvanized film is formed on the steel strip surface. It is formed. Next, the steel strip (9) is continuously withdrawn from the molten zinc bath (4), and the amount of plating is adjusted by a gas throttle nozzle (5) arranged directly above the bath. The plated steel strip (9) with the adjusted coating weight is subjected to a predetermined treatment by a minimum spangle device or a galvanile device (6) or the like.

Hot-dip galvanized steel strip manufactured in such a process,
Because of its relatively beautiful surface and excellent corrosion resistance, it is widely used in practice.

However, while hot-dip galvanized steel sheets have been used for building materials and pipes, and for home appliances and automobiles, they have recently been used mainly for inner panels. In addition, uniformity, smoothness and beautifulness of the surface are required. Furthermore, in terms of product type, thick plating,
Demand for new products such as high-strength galvanized steel sheets for the purpose of single-sided plating and weight reduction of structures is also high, and as a result, problems regarding the quality of the plated steel sheets by the conventional hot-dip galvanizing method and the plating process itself have become apparent. I have. The problems can be classified as follows.

I. Problems associated with the use of a hot-dip bath in which a large amount of plating metal is melted and held at all times. II. Problems caused by applying the gas drawing method to control the coating weight. III. Use of a long pretreatment furnace. The following is a detailed description of specific problems with each item.

I. Problems associated with the use of hot-dip bath 1) Fe is eluted from the surface of the steel strip in the bath, and so-called dross is often generated due to oxidation of the plating metal, which must be pumped and removed. In addition, loss of plating metal other than adhesion to the steel strip occurs.

2) Impurities are easily mixed into the plating bath, such as dross being generated in the plating bath and debris of the bricks constituting the pot, and these are attached to the steel strip and deteriorate the appearance.

3) Since the trace metal elements in the plating metal ingot that is put into the bath and the components that adhere to the steel strip and the components that are discharged out of the bath as by-products such as dross are different, contain the required elements as intended. It is difficult to adjust and control the plating bath components.

For this reason, various plating defects such as poor plating adhesion and poor galvaneal material alloying occur.

4) It is necessary to immerse steel mechanical parts such as rolls for steel strip passing, roll support arms, bearings, etc., in a high-temperature, highly corrosive plating metal bath.

For this reason, there arise problems such as erosion of these members and generation of dross accompanying the erosion, and furthermore, deterioration of the plating surface appearance due to erosion of the roll surface in the bath.

In addition, the erosion or damaged parts of these mechanical parts need to be regularly shut down for repair and replacement, and the production capacity of the equipment cannot be used effectively and maximized.

5) By using the roll for sheet passing (7) in the plating bath, the groove of the roll is easily transferred to the plating surface, and the appearance is deteriorated.

Further, even with the squeezing roll (8) installed before the gas squeezing, flaws on the surface of the steel strip due to contact between the roll and the steel strip and adhesion of minute dross particles may occur.

6) Discharge of bottom dross deposited on the bottom of the bath, discharge of top dross deposited on the bath surface, initial passing of steel strip into the bath, maintenance of rolls in the plating bath, etc. Work in the vicinity of a large amount of plating bath places a heavy burden on the operator and is dangerous.

7) Because only one type of plating is possible per pot,
When performing various kinds of plating, it is necessary to perform a bath change by pumping out a bath, or to prepare a pot in which a plating metal of a different kind is dissolved in advance and move the pot.

8) When a double-sided plating material and a single-sided plating material are produced by a single equipment, it is necessary to change the plating equipment in the pot part, and in addition to the equipment burden, much time and labor are required for switching. .

9) It is difficult to perform special plating such as double-sided different plating, multilayer plating, and double-sided thick plating.

II. Problems associated with the adjustment of the adhesion amount 1) The adjustment of the adhesion amount by the gas throttle is performed using gas such as air, combustion product gas, nitrogen gas, and steam. In the case of generated gas, nitrogen gas, or steam, the use of the gas itself is costly.

In addition, additional gas temperature control equipment and gas volume and gas pressure control devices are required.

2) When changing the target adhesion amount, it takes time to adjust the gas restriction condition, so that a product having the target adhesion amount cannot be obtained immediately.

3) Since the pressure and flow velocity distribution of the gas throttle gas in the width direction of the steel strip are not always uniform, it is not easy to obtain a uniform coating weight in the width direction.

4) When the gas from the nozzle collides with the hot-dip coating on the surface of the steel strip at the time of gas squeezing, fine splashes of the plating metal are generated, which adhere to the plating surface and deteriorate the appearance.

In addition, the droplets adhere to the gas discharge portion of the gas throttle nozzle and the vicinity thereof, and disturb the gas pressure and the flow velocity distribution.

5) At the time of gas squeezing, since the fluidity of the plated metal flowing down the steel strip surface is different in each part, large and small waveform patterns remain on the plated surface, which is a problem in appearance.

Also, this phenomenon is performed by performing gas restriction in an inert gas,
It is known that the reduction can be achieved if an oxide film is not formed on the plating surface. However, performing all the gas squeezing operations in an inert gas atmosphere has many problems in facilities and operation.

6) Splashes of the plating metal generated by the gas squeezing accumulate on the plating bath surface in an oxidized state. Since this is discharged outside the bath as a top dross, loss of plating metal occurs. Dross discharge also requires a lot of labor.

7) There is a coating amount range that can be adjusted by gas squeezing, and extremely thin plating materials (about 30 g / m ² or less) and thick plating materials (about 500 g)
/ m ² ) is difficult to manufacture.

In other words, in the case of thin plating, the amount of adhesion cannot be reduced by the gas impact force, and in the case of thick plating, it is difficult to keep the plating surface smooth and beautiful.

III.Problems in the pretreatment furnace In high-strength steel sheets with Si and Mn added, during direct heating, reduction and cooling operations in the pretreatment furnace, Si, Mn
Is concentrated on the surface layer to form an oxide film, and a phenomenon occurs in which plating adhesion and wettability are inhibited.

Such a phenomenon cannot be avoided unless a long pretreatment furnace as in the related art is used, and the types of steel that can be used as high-tensile steel are limited.

In contrast to the conventional hot-dip plating method described above,
In -207555, the nozzle is brought close to the running steel strip surface, and the molten metal supplied from the molten metal bath is sucked out of the nozzle by the wet adhesion between the molten metal and the steel strip surface, and is attached to the steel strip. Plating methods have been proposed.

This method applies a coating technique such as a high-viscosity paint, but it is a method of feeding molten metal from a molten metal tank to a nozzle, and the amount of plating applied is controlled by the head pressure of the molten metal tank. Therefore, a change in the height of the bath surface in the tank appears as a variation in the amount of plating, which has the disadvantage that the accuracy of the amount of plating is poor. In any case, a molten metal tank corresponding to a plating bath of an immersion type is required, and thus has various problems as described above.

[Summary of the Invention]

The present invention has been made in order to improve the above-mentioned drawbacks of the conventional method, and aims to provide a new continuous metal plating apparatus which does not require a plating metal bath and can control the amount of deposition with high precision. Things.

The apparatus of the present invention for achieving this object continuously feeds a plated metal sheet toward the surface of a moving steel sheet heated to a temperature equal to or higher than the melting point of the plated metal, and the tip side thereof is brought into contact with the steel sheet surface. A plating metal plate feeding device for sequentially melting, a heating device for preheating the plating metal plate, and an ultrasonic vibration plating surface adjustment device for adjusting a plating film surface formed on a steel plate surface by melting the plating metal plate; A continuous metal plating apparatus for a steel sheet, comprising: a surface adjusting plate to be brought into contact with a plating film surface; and an ultrasonic vibrator for applying ultrasonic vibration to the surface adjusting plate. It is.

Such a plating apparatus of the present invention can perform plating without using a molten metal bath at all, and also feeds a solid plated metal plate in the direction of a steel plate to be plated and melts the plate by the plating weight. In this method, the amount of plating can be controlled by the feeding speed of the solid plated metal plate, and therefore, high accuracy of the amount of deposition can be secured. Further, there is a problem that a plating film in which a plated metal sheet is melted on a steel sheet surface is apt to cause uneven plating adhesion and that the plating film is difficult to spread over the entire width of the steel sheet. Equipped with plating surface adjustment device of sonic vibration method,
The surface adjustment plate to which ultrasonic vibration is applied is brought into contact with the plating film surface, and by applying ultrasonic vibration to the plating film, the coating thickness of the plating metal is made uniform and the plating metal is evenly spread over the entire surface of the steel plate. As a result, the plated film having a uniform and smooth surface is obtained over the entire width of the steel sheet.

〔Example〕

 Hereinafter, embodiments of the present invention will be described.

FIG. 1 shows an embodiment of the present invention. (11) is a feed roll constituting a plating metal plate feeding device, (16) is a heating device for preheating a plating metal plate, and (14) is formed. This is a plating surface adjustment device for adjusting the plating film surface.
Further, (9) is a steel strip running continuously, and (10) is a plated metal plate to be brought into contact with the steel strip (9).

The feed roll (1
1) restraining the plated metal plate (10) from both sides and continuously feeding the plated metal plate (10) toward the surface of the steel strip (9) which is heated to a temperature equal to or higher than the melting point of the plated metal and moves;
In this embodiment, two pairs of feed rolls (11) are provided in the feed direction of the plated metal plate in such a manner that the tip side thereof is brought into contact with the steel strip surface to be sequentially melted.

The heating device (16) is for preheating the plated metal plate (10) in order to ensure the melting of the plated metal plate. In the present embodiment, the heating device (16) is disposed between the two pairs of feed rolls (11). I have. This heating device (16) is constituted by an induction heating device or the like.

The plating surface adjusting device (14) includes a plating metal plate (1
This is an apparatus for adjusting the plating film surface formed by the melting of 0). That is, the plating film formed by melting the plated metal plate (10) is apt to cause unevenness of the coating amount as it is, and is difficult to spread over the entire width of the steel strip. ) And the contact area (1
A plating surface adjustment device (14) is provided downstream of 2) to make the plating film uniform and smooth.

The plating surface adjusting device (14) in the apparatus of the present invention is of an ultrasonic vibration type, which has an ultrasonic vibrator (15) and a surface adjusting plate (140) to be brought into contact with the plating film surface,
The ultrasonic vibrator (15) applies ultrasonic vibration of an appropriate frequency and output to the surface adjustment plate (140).

According to the above apparatus of the present invention, the steel strip (9) is subjected to metal plating as follows. That is, the traveling steel strip (9) is heated to a temperature equal to or higher than the melting point of the plated metal by a heating device (not shown), and the plating metal preheated by the heating device (16) is directed toward the surface of the steel strip (9). The plate (10) is continuously fed out by a feed roll (11) constituting a plated metal plate feeder, and the leading end thereof is brought into contact (12) with the steel strip surface. The plated metal plate (10) is melted by heat conduction from the steel strip (9) and adheres as a plating film (13) on the steel strip surface. Then, the plated metal plate (10) is continuously fed to the surface of the running steel strip (9), and is sequentially melted and adhered to the steel strip surface. Will be done.

The plated metal that has melted from the tip of the plated metal plate due to contact with the steel strip (9) adheres to the steel strip surface as shown by the hatched portion in the figure. Plating metal plate (10) to cover almost the entire width of the surface
Is preferably determined in accordance with the width of the steel strip (9).

The coating weight is controlled by the feed rate of the plated metal plate (10), and therefore, the feed rate is determined according to the target coating weight.

The plating film formed by melting the plated metal plate (10) tends to cause unevenness of the coating amount as it is, and it is difficult to spread over the entire width of the steel strip. Therefore, the plating film is made uniform by the plating surface adjustment device (14). You. That is, when the surface adjustment plate (140) of the plating surface adjustment device (14) is brought into contact with the surface of the steel strip to which the plating metal is attached with an appropriate rolling force, ultrasonic vibration is added to the plating film, The coating thickness of the plating metal is made uniform, and the plating metal spreads uniformly over the entire surface of the steel strip. Further, poor wetting of the plating is remarkably reduced, and a uniform plating film having a smooth surface can be obtained.

In the method of the present invention, the bonding between the plating film and the steel strip is based on the interdiffusion phenomenon between the metals, as in the ordinary hot-dip plating method.
The surface must be clean and free from oxide contamination.

Therefore, when the method of the present invention is carried out in the atmosphere, it is preferable to apply the method to a flux-treated steel strip surface.
In addition, it is preferable that the steel strip surface subjected to the reduction treatment in the pretreatment furnace be carried out in an inert gas or reducing gas atmosphere.

The steel strip to be plated only needs to have a clean surface, and therefore can be applied to a steel strip immediately before entering a bath in a conventional hot-dip galvanizing line and a steel strip on the exit side of a continuous annealing line. Needless to say, the present invention can be implemented by a combination with another type of surface cleaning device.

FIG. 2 shows a more specific embodiment of the present invention,
The apparatus of the present invention is connected to a rear end (17) of a pretreatment furnace of a conventional hot-dip plating facility shown in FIG.

In this embodiment, the plating metal sheet feeding device includes a feeding roll (11) and a plating metal sheet feeding cylinder (21), (22).
And the like. A large number of plated metal sheets (10) to be fed are set in the holder (20), and are automatically bitten by the feeding rolls (11) by the plated metal sheet feeding cylinders (21) and (22). Sent as

Further, the entire plating surface adjusting device (14) is held by a special cylinder (23) having an impact buffer device. This cylinder (2
By being held in 3), the surface adjusting plate constituting the device can be brought into extremely slight contact with the steel strip surface, and has a structure that can be retracted to a predetermined position when not in use. Further, a heating device is incorporated in the surface adjusting plate, and is heated to a predetermined temperature before use.

According to the embodiment shown in FIG. 2, the steel strip (9) is subjected to an inert gas or reducing gas atmosphere in the seal box (18) while the surface is reduced and cleaned in the pretreatment furnace. Then, it is heated by a heating device (19) to a temperature required for welding the plated metal.

On the other hand, the feed roll (1
1) and plating metal plate feeding cylinder (21), (22)
The plated metal plate (10), which has been preheated by the heating device (16), is continuously fed from the direction almost perpendicular to the surface of the steel strip by the plating metal plate feeder composed of Is performed. The plated metal plate (10) is sequentially fed toward the steel strip surface by the feed roll (11) by an amount corresponding to the amount consumed for plating.

The surface adjustment plate of the plating surface adjustment device (14) is brought into contact with the steel strip surface after plating metal welding with an appropriate pressure, so that the plating film is made uniform and smooth.

The plated steel strip whose surface has been adjusted in this way is cooled through various treatments, and then goes out of the seal box kept in an inert gas or reducing gas atmosphere. In the embodiment shown in FIG. 2, the surface-conditioned plated steel strip is alloyed in an alloying heating furnace (24). This alloying furnace (2
In 4), the steel strip (9) is subjected to a heat treatment by an electromagnetic induction heating method or the like, and an alloying treatment of the plating film is performed. Also,
(25) is a cooling device by blowing gas in an inert gas or reducing gas atmosphere, (26) is a water cooling device in the same atmosphere, and (27) is a drying device in the same atmosphere. The treated steel strip (9) is led to the atmosphere after being cooled to room temperature in these devices.

In the other drawings, (28) is a steel strip surface treatment apparatus before plating, and Si, Mn which is concentrated on the surface when high tensile steel strip of high Si, Mn is heated and reduced in a pretreatment furnace. The purpose is to remove oxide films such as. In this apparatus, the oxide film is removed by mechanical polishing removal by brushing or the like and electrical destruction removal by discharge treatment or the like. Also,
This part also has an inert gas or reducing gas atmosphere.

FIG. 2 shows an example of a horizontal plating apparatus, but it goes without saying that the present invention can be applied to a vertical apparatus.

The present invention can eliminate most of the drawbacks of the conventional hot-dip plating method, and its effects are as follows.

I. Advantages of not requiring a hot-dip plating bath 1) Since there is no dross as in the case of using a plating bath, there is no loss of plating metal other than adhering to a steel strip.

2) Dross, impurities, etc. do not adhere to the surface, and the appearance is kept beautiful.

3) Since the plating metal is directly welded, almost the same components as those of the plating metal plate are plated, the components in the plating layer are made uniform, and the components can be easily controlled.

4) There is no need to use parts immersed in the bath, so there is no need to stop operation for repairing or replacing eroded machine parts.

5) Since it is not necessary to use a roll in the bath, there is no deterioration in product quality such as deterioration in appearance due to transfer of the roll groove and breakage of the hip due to the squeezing roll.

6) Eliminates the need for bottom dross and top dross discharge work, threading work for steel plates in the bath, and maintenance work for rolls in the bath.
The burden on the operator is significantly reduced.

7) When performing various types of alloy plating, it is only necessary to change the plating metal plate to be supplied to the steel strip, and it is not necessary to perform a large-scale operation such as changing a bath or moving a pot. It is feasible.

For example, various Zn-Al alloy plating (5-100% Al),
Pb-free Zn plating for the purpose of spangle elimination can be easily performed.

8) Various types of plating, such as single-side plating, multilayer plating, double-sided thick plating, and double-sided dissimilar plating, can be easily performed by selecting and changing the arrangement, supply mode, and feeding speed of the plated metal plate. Can be.

For example, a single-sided plated steel sheet can be easily manufactured by stopping the feeding of the plated metal sheet on one side, and a thick-plated steel sheet can be easily manufactured by changing the feeding speed of the plated metal sheet on both sides.

Further, it becomes possible to manufacture a dissimilar alloy plated steel sheet having a different plating layer component for each side.

II. Advantages in Adjusting the Adhesion Amount 1) The adjustment of the adhesion amount of the plating can be basically performed by adjusting the feeding amount of the plated metal plate. That is, the plating method of the present invention is a method in which a solid plated metal plate is fed in the direction of the steel plate to be plated and melted by a plating weight on the steel plate surface, and this is adhered to the steel plate. It can be controlled by the feeding speed of the plating metal plate, and therefore, a high degree of adhesion accuracy can be secured.

In addition, there is no need for the gas throttling performed in the conventional hot-dip plating, and there is no need for a gas throttling nozzle which is troublesome for maintenance, and associated adjusting devices for gas temperature, supply amount, pressure and the like. Further, the operation cost of the pressure increasing blower and the cost of the gas itself are completely unnecessary.

2) When changing the target adhesion amount, it is only necessary to change the feeding speed of the plated metal plate, and the adhesion amount can be changed quickly.

3) The surface adjustment after plating welding is performed by pressing the surface adjustment plate to which ultrasonic vibration is applied in parallel to the steel strip surface, so that the coating thickness of the plating metal is made uniform and the plating metal is removed. As a result of spreading over the entire width of the steel strip and significantly reducing poor wetting of the plating, a plated film having a uniform and smooth surface can be obtained.

4) After plating, by keeping the steel strip in an atmosphere of inert gas or reducing gas until the temperature of the steel strip drops to around room temperature, the surface of the plating film is oxidized, and a wavy pattern on the surface such as that caused by gas squeezing is generated. And beautiful surface properties can be obtained.

5) Since the adhesion amount can be adjusted by controlling the feeding amount of the plated metal plate, it is possible to obtain a product of ultra-thin plating and extra-thick plating which was impossible with the conventional gas drawing method.

III. Advantages in equipment structure 1) By not using a plating bath and a gas throttle, it is possible to easily seal the entire plating portion with an inert gas or a reducing gas.

Therefore, the formation of an oxide film on the plating surface is suppressed,
A product with a beautiful surface can be obtained.

2) Immediately before plating, the surface of the steel plate to be plated can be easily cleaned (eg, polished by brushing, destruction of an oxide film by electric discharge). It can also be applied to hard-to-plate steel types whose use has been restricted in conventional hot-dip coating, such as high-tensile steel with Mn addition.

〔The invention's effect〕

As described above, according to the present invention, metal plating can be continuously performed without using a plating bath which has conventionally caused various problems. In particular, in the present invention, the solid plating metal plate is fed in the direction of the steel plate to be plated, and is melted by the plating weight on the steel plate surface, and then is adhered to the steel plate. It can be controlled by the feeding speed of the plate, so that there is an excellent effect that a high degree of adhesion accuracy can be secured. In addition, there is a problem that a plating film in which a plated metal plate is melted on a steel sheet surface is apt to cause uneven adhesion, and the plating film is difficult to spread over the entire width of the steel plate. Equipped with a plating surface adjustment device of the ultrasonic vibration type, the surface adjustment plate to which ultrasonic vibration was applied is brought into contact with the plating film surface, and by applying ultrasonic vibration to the plating film, the coating thickness of the plating metal is made uniform. Along with
As a result, the plated metal spreads uniformly over the entire width of the steel strip, and the poor wetting of the plating is significantly reduced. As a result, a plated film having a uniform surface over the entire width of the steel sheet can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a side sectional view showing a more specific embodiment of the present invention, and FIG. 3 is a side view showing an example of a conventional apparatus. 9 ... steel strip, 10 ... plated metal plate, 11 ... feed roll,
12 contact part, 13 plating film, 14 plating surface adjustment device, 15 ultrasonic transducer, 16 heating device, 17
… Back end of pre-treatment furnace for hot-dip plating equipment, 18 …… Seal box, 19 …… Heating device, 20 …… Holder, 21 …… Plating metal plate feeding cylinder, 22 …… Plating metal plate feeding cylinder, 23 …… Cylinder, 24: Alloying heating furnace, 25: Water cooling device, 26: Water cooling device, 27: Drying device, 28: Steel strip surface treatment device, 140: Surface adjustment plate

Claims (1)

(57) [Claims] 1. A plating metal plate feeder for continuously feeding a plating metal plate toward a surface of a moving steel plate heated to a temperature equal to or higher than the melting point of the plating metal, and bringing the leading end side into contact with the steel plate surface to melt sequentially. A heating device for preheating the plated metal plate, and a plating surface adjustment device of an ultrasonic vibration type for adjusting a plating film surface formed on a steel plate surface by melting the plated metal plate, A continuous metal plating apparatus for a steel sheet, comprising: a surface adjusting plate to be brought into contact with a plating film surface; and an ultrasonic vibrator for applying ultrasonic vibration to the surface adjusting plate.