JP2848208B2 - Hot-dip metal plating equipment - 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 metal plating apparatus.

2. Description of the Related Art A hot-dip galvanized steel sheet typified by a hot-dip galvanized steel sheet has a clean surface, and an activated steel strip is immersed in a hot-dip metal plating bath, pulled up through a sink roll in the bath, and pulled up. Next, scraping the excess plated metal by so-called gas wiping injecting gas from both sides of the steel strip,
It is manufactured by controlling to a predetermined plating adhesion amount.
By the way, in recent years, the demand for hot-dip galvanized steel sheets as rust-preventive steel sheets has increased, and therefore, in hot-dip galvanizing equipment, high speed, automation, and thinning are required for the purpose of improving productivity and reducing costs. There is a demand for uniform and beautiful plating adhesion.

[0002]

The amount of hot-dip galvanized steel that adheres to a steel strip when it exits the hot-dip galvanizing bath is determined by the bath temperature, ie, the viscosity of the metal to be plated, the temperature of the steel strip, and the line speed of the steel strip. However, since the bath temperature and the bath penetration temperature of the steel strip are generally controlled to be constant, the amount of molten zinc adhering to the steel strip is uniquely determined by the line speed of the steel strip. Zinc deposits increase. Therefore, depending on the line speed and the degree of thinning, it is necessary to remove a large amount of excess plating by gas wiping. However, if the wiping gas ejection flow rate is increased to scrape off excess plating, a large amount of so-called splash occurs, which adheres to the wiping nozzle or steel strip, and the production volume decreases due to nozzle cleaning. Or the quality of the plated steel sheet is reduced.

[0003] In gas wiping, the so-called edge overcoat is liable to occur, that is, the basis weight of the steel strip edge portion becomes thicker than that of the steel strip center portion. This edge overcoat causes load collapse during coil winding, and also causes a delay in alloying of the steel strip edge portion in the heating alloying process performed immediately after plating, causing an edge unalloyed process. In order to prevent the occurrence of such an edge overcoat, various proposals as described below have been conventionally made.

As shown in FIG. 18, the slit gap 16 of the wiping nozzle is gradually increased from a position slightly closer to the line center than the steel strip edge toward both ends of the nozzle, and the movement of the wiping gas colliding with the steel strip edge is increased. A method of increasing the molten zinc drawing force at the edge by increasing the pressure. JP-B-55-41295 and JP-A-57-1583
As shown in FIG. 19, an auxiliary nozzle 17 is provided above the wiping nozzle so as to blow gas only to the edge of the steel strip so as to be adjustable in the nozzle width direction. How to increase the drawing power of the part.

In a method called an edge plate method, a dummy edge plate 18 is provided at a portion of a steel strip edge portion where a wiping gas collides as shown in FIG. 20 to prevent edge overcoating. According to the method proposed in JP-A-2-47247,
As shown in FIG. 21, a method for preventing edge overcoat by pressing a knife 19 for scraping plating metal against the end face of the steel strip and removing only the plating metal adhering to both end faces of the steel strip. According to the method proposed in JP-A-3-6358, as shown in FIG. 22, a plating metal adhesion amount control plate 20 is installed over the entire width of the steel strip on the surface of the plating bath, and the plating metal is removed without using gas wiping. How to control the lift.

[0006] However, these conventional methods have the following problems. In the first method, since the positions of both ends of the nozzle in which the slit gap 16 is to be increased differ depending on the steel strip width, in order to appropriately prevent edge overcoating, the wiping nozzle is replaced according to the steel strip width. However, there is a disadvantage that the productivity is reduced due to the replacement. Further, since the slit gap 16 at the position of the steel strip edge is large and the amount of wiping gas ejected is large, splash and noise are remarkably generated. In particular, there is a problem that a large amount of splash adheres to the wiping nozzle or the steel strip, which lowers the productivity for cleaning the nozzle or lowers the quality of the plated steel sheet.

In the method (1), since the position of the auxiliary nozzle 17 can be adjusted according to the width of the steel strip, the problem of productivity reduction due to nozzle replacement as in the method (2) can be avoided.
There is the same problem as described above in that the generation of splash and noise is remarkable. According to the method, when the gap between the edge plate 18 and the steel strip is too large, the effect of preventing the edge overcoat is reduced. Therefore, the edge plate 18 is arranged at a fixed interval with respect to the steel strip in accordance with the vibration of the steel strip passing therethrough. You have to keep following. However, this follow-up mechanism is required to have high responsiveness in high-speed threading, and therefore has the disadvantage of extremely high equipment and repair costs.

In the method (1), there is a problem that the plating metal scraped off by the knife (19) scatters to generate a splash, and the splash adheres to the wiping nozzle or the steel strip as in the above method. Further, since the wiping gas is ejected at a high speed, it is difficult to collect the splash generated by the scraping by the knife 19 with a simple collecting device.

In the method (1), since a wiping nozzle is not used, problems peculiar to the gas wiping method, such as splash scattering, can be avoided. However, since the gap between the adhesion control plate 20 and the steel strip is small, natural rotation in the natural rotation is not possible. When roll coating is performed, roping, which is a problem, occurs, and there is a disadvantage that the smoothness of the plating surface is inferior to that of the gas wiping method. Further, when changing the sheet width, particularly when the succeeding steel strip is wider than the preceding steel strip, the end of the succeeding steel strip contacts the adhesion amount control plate 20, and the steel strip breaks or the adhesion amount control plate 20 It is easy to break and significantly reduces productivity. Further, even if the adhesion amount control plate 20 is opened at the time of passing through the steel strip connection portion so as to temporarily widen the gap with the steel strip, dross on the bath surface is reduced when returning from the opening to the original position. There is a problem that the surface quality of the plating deteriorates due to, for example, the zinc on the surface of the coating amount control plate being exposed to the atmosphere and being oxidized or solidified to impair the smoothness of the control plate surface when it is rolled up or opened.

The present invention has been made to solve the problems of the prior art, and has as its object to freely control the amount of plating metal lifted along with the strip from the molten metal plating bath regardless of the line speed. Can be controlled,
Accordingly, it is an object of the present invention to provide an apparatus that enables a reduction in the amount of excess plating squeezing in gas wiping or the like and that can effectively prevent the occurrence of splash. Another object of the present invention is to provide an apparatus capable of effectively preventing the occurrence of edge overcoat as well as controlling the amount of metal plating adhered.

[0011]

In order to achieve the above object, a basic structure of a hot-dip metal plating apparatus of the present invention is as follows. (1) meet position shallow below the bath surface of the molten metal plating bath
And roll rotation with hot metal plating bath surface
Bath space for flowing molten metal flow
A hot-dip metal plating apparatus comprising, at a depth position, a pair of adhesion amount control rolls for controlling the adhesion amount of plating metal to a strip, which is provided in parallel with a strip width direction across a strip pass line. (2) A dummy plate is arranged at least in a range extending under the bath surface of the hot-dip metal plating bath and in the vicinity of the bath surface so as to be close to both edges of the strip to be passed and substantially flush with the strip. At a shallow position below the bath surface of the hot-dip metal plating bath, and
Bath space for the flow of molten metal accompanying the
A pair of adhesion amount control rolls for controlling the amount of plating metal adhering to the strip are provided at a depth position where the strip can be formed, and are provided in parallel with the strip width direction including the dummy plate with the strip pass line interposed therebetween. Metal plating equipment.

(3) In the apparatus according to the above (1) or (2), a suction means for sucking the plating metal near both edges of the strip to be passed to a shallow position below the bath surface of the molten metal plating bath. Hot-dip metal plating equipment. (4) In the apparatus according to the above (1) or (2), an electromagnetic field for controlling a plating metal flow near both edges of a strip to be passed, near or below a bath surface in a molten metal plating bath. Metal plating equipment equipped with an electromagnetic coil that provides (5) In the apparatus according to the above (1) or (2), the coating amount control roll includes an electromagnetic coil for providing an electromagnetic field for controlling a plating metal flow near both edges of the strip to be passed. apparatus.

[0013] In the above apparatus, it is preferable that the adhesion amount control roll is configured to be able to adjust a gap with the strip pass line. Preferably, the plating metal suction nozzle and the electromagnetic coil are configured to be movable in the strip width direction. In a device in which the adhesion amount control roll incorporates an electromagnetic coil, it is preferable that the electromagnetic coil be divided into a plurality of pieces in the strip width direction so that the power applied to each divided coil can be individually controlled. Gas blowing means for blowing a gas (a non-oxidizing gas, a weakly oxidizing gas, or a reducing gas) onto the bath surface near the strip pass line can be provided on both sides of the strip pass line above the plating bath surface. .

In place of the gas blowing means, a cover for covering a bath surface through which the strip pass line passes is provided, and a gas for supplying a gas (a non-oxidizing gas or a weakly oxidizing gas or a reducing gas) to the inside of the cover is provided. Supply means can be provided. In the apparatus of the present invention, it is possible to set the adhesion amount control roll at a predetermined position without adjusting the position, but in this case, it is possible to control the rotation speed of the roll. Therefore, it is preferable to arrange the roll at an appropriate position that does not contact the strip.

[0015]

The present inventors conducted various experiments and studies on the liquid film flow of the plating metal lifted from the plating bath accompanying the strip, and as a result, obtained the following knowledge. First, FIG. 15 shows a cross section at the center in the strip width direction when the strip goes out of the plating bath surface. In general,
Above the sink roll in the plating bath, a stabilizing roll 21 and a collecting roll 22 are arranged on each side of the strip for the purpose of correcting the shape of the strip and adjusting the pass line. Normally, these rolls are located at a relatively shallow position below the bath surface,
Further, although the collecting roll 22 is arranged deeper below the bath surface, the amount of plated metal lifted along with the strip S coming out of the bath surface depends on the strip surface where the roll is arranged deeper below the bath surface. The strip surface side (stabilizing roll 21 side) in which the rolls are arranged at a shallow position below the bath surface is less than the side (collecting roll 22 side). In some cases, the roll is disposed only at a shallow position below the bath surface on one side of the strip, but in this case, the amount of plating metal lifted along with the strip S is also reduced to the strip surface on which the roll is not disposed. In comparison
There is less on the strip side where the rolls are arranged at a shallow position below the bath surface.

This phenomenon is caused by a strong plating metal flow (roll accompanying flow X) directed in a direction away from the strip S as the roll rotates, as shown in FIG. In other words, not only when the roll is not arranged, but also when the roll is arranged, it is located deep below the bath surface (in the drawing, the collecting roll 22).
On the side), even if the roll accompanying flow X as described above occurs, its influence does not reach near the bath surface, so that the plating metal near the strip surface is hardly affected by the roll accompanying flow X to the strip S. Accompany. On the other hand, when the roll is installed at a shallow position below the bath surface (in the figure, the stabilizing roll 21 side), the plating metal near the bath surface is
Plating metal accompanying strip S (strip flow Y) and plating metal accompanying roll (roll accompanying flow X)
As a result, the amount of plating metal accompanying the strip S is reduced.

Further, as a result of the occurrence of the roll entrainment flow as described above, as shown in FIG. 16, an amount of plating metal corresponding to the plating metal carried away by the roll entrainment flow X is transferred from the outside in the strip width direction to the center of the strip. (The plating metal flow indicated by Z in the figure). That is,
In the vicinity of both edges of the strip, the roll entrainment flow X
The plating metal flow Z is formed by the bath surface difference between the bath surface Hb depressed by the plating metal flow accompanying the strip and the other bath surface Ha. Since the effect of the roll accompanying flow X described above does not appear at the strip edge due to the plating metal flow Z, the amount of the plating metal lifted along with the strip S is larger than that at the center of the strip. Therefore, the distribution in the strip width direction of the amount of plating metal lifted by the strip S contributes to the edge overcoat. Such a phenomenon is particularly noticeable when the effect of the roll entrainment flow is large,
Usually, as shown in FIG. 15, the stabilizing roll 21 and the collecting roll 2 are provided on both sides of the strip S.
2, the amount of plated metal lifted along with the strip S is affected by the roll tangential flow X, and although the degree varies depending on the depth of the roll below the bath surface, the strip S is The distribution of the amount of plating metal to be lifted occurs in the strip width direction.

As described above, the amount of plating metal lifted along with the strip changes depending on the presence or absence or magnitude of the accompanying flow of the rotating roll disposed in the plating bath, and the edge overcoat is caused only by gas wiping. However, it was found that the amount of the plating metal lifted by the strip from the plating bath itself was also caused by the distribution in the strip width direction due to the action of the roll accompanying flow.

As a result of further studies based on such knowledge, the present inventors have found that by controlling the roll accompanying flow itself, the amount of plated metal lifted along with the strip is controlled regardless of the line speed. Also, in this case, by taking appropriate measures, the amount of plating metal lifted along with the strip by the roll accompanying flow can be made uniform in the strip width direction. The amount of plating metal to be applied is reduced on the strip edge side compared to the center of the strip, and the plating metal wraps around from the center of the strip to the edge during gas wiping, that is, the same principle as that of the edge overcoat is used. This achieves a uniform plating weight in the strip width direction. It found that it is intended that the present invention has been completed.

As shown in FIG. 15, a relatively shallow position below the bath surface (however, when the roll is
Creates a bath space for the flow of the accompanying molten metal
The rotating roll disposed at a position at a sufficient depth serves to reduce the amount of plated metal lifted up along with the strip by the flow accompanying the roll. Therefore, by selecting rotation / non-rotation of the adhesion amount control roll of the apparatus of the present invention, and by controlling the roll accompanying flow by controlling the rotation speed when rotating the roll, the amount of plating metal lifted along with the strip can be freely adjusted. Can be controlled. That is, if the adhesion amount control roll is rotated, a roll accompanying flow that causes a portion of the plated metal near the strip surface to move away from the strip occurs , and this roll accompanying flow is generated by the adhesion amount control roll.
Because it escapes smoothly through the upper bath space,
Compared to a case where the roll is not rotated, it is possible to reduce the amount of plated metal lifted along with the strip. In addition, if the rotation speed of the adhesion amount control roll is increased, a larger roll accompanying flow is generated, so that the amount of plating metal lifted along with the strip can be further reduced. And by controlling the amount of plating metal,
By reducing the amount of excess plating metal lifted by the strip, the jet flow velocity of the wiping gas can be reduced, and as a result, generation of splash can be suppressed. The coating amount control roll generally rotates in a state of non-contact with the strip, but if there is no problem in relation to the strip passing speed,
It may be rotated while in contact with the strip.

Further, by changing the gap between the coating amount control roll and the strip pass line, the strength of the flow accompanying the roll and the state of the flow can be changed. Therefore, the gap between the coating amount control roll and the strip pass line can be reduced. By making appropriate adjustments, it becomes possible to more appropriately control the flow accompanying the roll. Further, the pair of adhesion amount control rolls provided with the strip pass line interposed therebetween is controlled in accordance with the target coating weight of each surface of the strip, or in consideration of the influence of the roll accompanying flow caused by the stabilizing roll located below. The rotation speed control and the gap adjustment with the strip pass line may be separately performed.

In an apparatus in which a dummy plate is arranged close to both edges of a strip, the strip edge portion where the influence of the roll entrainment flow is small and the amount of lift of the plated metal should be large is usually replaced by the dummy plate. The amount of plating metal lifted along with the strip does not occur in the width direction of the strip, and the amount of plating metal in the width direction becomes uniform. In the apparatus provided with a plating metal suction nozzle, the suction nozzle suctions and removes the plating metal near the strip edge, so that the bath surface near the strip edge also has a bath surface H in FIG.
b, the amount of plated metal lifted along with the strip can be made uniform in the strip width direction.

Further, the amount of plating metal lifted along with the strip is reduced on the edge side compared to the center of the strip by sucking and removing the plating metal in the vicinity of the strip edge by the suction nozzle. By wrapping the plating metal at the center of the strip toward the edge during wiping, that is, by utilizing the principle of edge overcoating, it is possible to obtain a uniform basis weight in the strip width direction. Further, in this case, since the amount of excess plating metal at the strip edge portion before the gas wiping is small, the jet flow velocity of the wiping gas can be reduced accordingly, and the generation of splash can be more effectively prevented. Further, by making the suction nozzle movable in the strip width direction, even if the width of the strip to be plated changes, the suction nozzle can be placed at a position corresponding to the strip edge.

In the apparatus provided with both the dummy plate and the suction nozzle, the action of the dummy plate can be supplemented by sucking the plating metal near the strip edge by the suction nozzle. In this device, the action of the suction nozzle is added, so that the width of the dummy plate can be made relatively small. In an apparatus provided with an electromagnetic coil for controlling a plating metal flow, a magnetic pressure is applied to a plating metal near a strip edge portion by an electromagnetic field generated by the electromagnetic coil. This magnetic pressure causes a flow of the plating metal opposite to the plating metal flow Z which is about to flow into the strip edge portion as shown in FIG. 16, thereby preventing the plating metal flow Z from being generated as a result. Therefore, the bath surface in the vicinity of the strip edge can be maintained at the level of the bath surface Hb in FIG. 16 (that is, the bath surface Hb can be maintained over the entire width of the strip), and the plating metal lifted along with the strip can be maintained. The amount can be made uniform in the width direction of the strip.

FIGS. 17A and 17B schematically show the operation of the above-mentioned electromagnetic coil, wherein a is a strip and b is an electromagnetic coil. When an alternating current is applied to a pair of electromagnetic coils b disposed opposite to both sides of each edge of the strip a, a magnetic field B is generated, and an induced current is generated in the plated metal in a direction perpendicular to a drawing (paper surface). The flow and the states of FIG. 1 and FIG. 2 occur alternately. That is, FIG.
In the case of, current flows in the direction from the front to the back of the drawing,
In the case of FIG. 2B, a current flows from the back of the drawing to the front. Then, a force F is applied to the plated metal (conductor) according to Fleming's left-hand rule between the induced current and the magnetic field B.
The force F acts to push the plating metal near the strip edge outward from the strip a, that is, in the direction opposite to the direction of the plating metal flow Z shown in FIG.

Further, by utilizing the above-mentioned operation more positively, the electromagnetic coil gives an electromagnetic field which generates a plating metal flow in the opposite direction to the plating metal flow Z as shown in FIG. It is also possible to generate a plating metal flow flowing outward from the part,
In this case, the amount of plating metal adhering to the strip edge portion side can be made smaller than that of the strip central portion, so that the plating metal at the strip central portion goes around the edge portion side during gas wiping, that is,
By utilizing the principle of edge overcoat, a uniform basis weight can be obtained in the strip width direction. Further, in this case, since the amount of excess plating metal at the strip edge portion before the gas wiping is small, the jet flow velocity of the wiping gas can be reduced accordingly, and the generation of splash can be more effectively prevented. Also, by making this electromagnetic coil movable in the strip width direction,
Even if the width of the strip to be plated changes, the electromagnetic coil can be placed at a position corresponding to the strip edge.

In an apparatus in which dummy plates are arranged close to both edges of the strip together with the electromagnetic coil,
The action of the dummy plate is supplemented by the action of the magnetic pressure by the electromagnetic coil described above. In addition, in this device, since the action of the electromagnetic coil is added, in the apparatus having the adhesion amount control roll having the built-in electromagnetic coil that can make the width of the dummy plate relatively small, by the action of the electromagnetic coil similar to that described above, The amount of plated metal lifted along with the strip can be made uniform in the strip width direction. Further, in this apparatus, the electromagnetic coil in the roll is divided into several parts, and the electric power applied to each divided coil is changed in accordance with the position of the strip edge, thereby obtaining a magnetic pressure corresponding to the change in the strip width. As a result, appropriate control of the plating metal flow in the vicinity of the strip edge as described above becomes possible.

In an apparatus provided with gas blowing means on both sides of the strip pass line above the plating bath surface, a non-oxidizing gas such as an inert gas or an oxygen concentration is supplied from the gas blowing means onto the bath surface near the strip pass line. Is sprayed with a weakly oxidizing gas (preferably having an oxygen concentration of less than 5%) or a reducing gas. Since the atmosphere on the bath surface is generally air, there is a problem that the plating metal is oxidized when the bath surface is disturbed by the adhesion amount control roll or the like. In addition, when the plating metal near the strip edge is sucked from the suction nozzle, the atmosphere on the bath surface is also sucked into the suction nozzle together with the plating metal, so that oxidation of the sucked plating metal is promoted. On the other hand, by performing the above-mentioned gas spraying on the bath surface in the vicinity of the strip pass line from the gas blowing means, oxidation of the plating metal on the bath surface is suppressed, and
Since the oxidizing gas (air) is not sucked into the suction nozzle,
The oxidation of the plating metal sucked by the suction nozzle is also suppressed. In particular, when a reducing gas is blown, the oxidation of the plated metal can be more effectively prevented.

Further, in an apparatus provided with a cover for covering the bath surface through which the strip passes, a non-oxidizing gas such as an inert gas or a weakly oxidizing gas having a low oxygen concentration (preferably, (Concentration less than 5%) or a reducing gas is supplied, and the inside of the cover is kept in such a gas atmosphere. By covering the bath surface through which the strip passes with the cover, the bath surface is disturbed by the wiping jet from the gas wiping nozzle located above, and the amount of plating metal lifted along with the strip is not uniform in the strip width direction. And oxidation of the plating metal on the plating bath surface is prevented, and the oxidizing gas (air) is not sucked into the suction nozzle of the plating metal. Is also prevented. In particular, when a reducing gas is supplied to the inside of the cover, even if an oxidized plating metal flows into the cover or an oxidizing gas flows into the cover, oxidation of the plating metal is prevented, and the oxidized plating metal is prevented from flowing. The material is also reduced, and the oxidized plating metal is prevented from adhering to the strip.

[0030]

1 and 2 show an embodiment in which the present invention is applied to a hot dip galvanizing apparatus for strip (steel strip). In the drawing, 1 is a hot-dip galvanizing bath, 2 is a sink roll disposed in the hot-dip galvanizing bath, 3 is a stabilizing roll, 4 is a collecting roll, and 9 is a gas wiping nozzle provided above the bath surface.

[0031] In relatively shallow position under the upper bath surface of the stabilizer Rising roll 3 and the collecting roll 4
And roll rotation between hot metal plating bath surface
Creates a bath space for the flow of the accompanying molten metal
A pair of rotatable adhesion amount control rolls 5 for controlling the amount of adhesion of the plating metal is provided at the position at the depth of the cut, in the strip width direction (strip width direction including a dummy plate described below) across the strip pass line. They are provided in parallel to each other. The adhesion amount control roll 5 is rotatably supported by a roll base 11 on which the stabilizing roll 3, the collecting roll 4, and the sink roll 2 are supported, and is rotationally driven by a motor 14a. The adhesion amount control roll 5 is capable of controlling the rotation speed and is provided with a position adjusting means (not shown) for adjusting the gap with the strip pass line. Further, the dummy plate 6 is arranged near the both edges of the strip S and flush with the strip S so as to extend over the bath surface and in the vicinity of the bath surface and below the bath surface. The dummy plate 6 is preferably configured to be position-adjustable in the strip width direction so as to be able to cope with a change in the strip width.

A cover 7 for covering a bath surface through which the strip S passes is provided above the adhesion amount control roll 5, and gas supply means 8 (gas supply nozzle) is provided inside the cover 7.
The gas can be supplied from. The cover 7 is formed of a box having an open lower end, and is arranged so that the lower end is immersed below the bath surface of the plating bath. A slit 71 for passing a strip is formed at the center of the cover 7. The upper surfaces 72 on both sides of the strip pass line of the cover 7 are configured to be concavely curved in the wiping gas injection direction, and the wiping gas (air) ejected from the upper wiping gas nozzle and colliding with the strip. Is smoothly released to the outside of the cover to prevent the oxidizing gas from flowing into the cover as much as possible. In other drawings, 14
b is a motor for driving the collecting roll, and 15 is a snout.

FIGS. 3 and 4 show an embodiment of an apparatus provided with a suction nozzle. Instead of the dummy plate 6, a shallow position below the bath surface (just below the bath surface) near both edges of the strip. Suction nozzle 10 for sucking plating metal
Is provided. The suction nozzle 10 is configured to be movable in the strip width direction by position adjusting means (not shown). The suction port of the suction nozzle 10 is located inside the cover 7. Since other configurations are the same as those of the embodiment described above, the same reference numerals are given and the detailed description is omitted.

FIGS. 5 and 6 show an embodiment of an apparatus provided with a dummy plate and a suction nozzle. The apparatus shown in FIGS. 1 and 2 and the embodiment shown in FIGS. 3 and 4 are shown in FIGS. It has a structure provided with a suction nozzle 10 similar to that described above. The structure of the suction nozzle 10 and other components are the same as those in the above-described embodiment. FIGS. 7 and 8 show an embodiment of an apparatus provided with an electromagnetic coil. Each of the devices 1 opposed to each other across the edge of the strip S is placed near or below the bath surface in the plating bath. A pair of electromagnetic coils 30 are provided. The electromagnetic coil 30 applies an electromagnetic field for controlling the flow to the plated metal near the strip edge. This electromagnetic coil 30 is provided with position adjusting means (not shown).
Are configured to be movable in the strip width direction. Since other configurations are the same as those of the embodiment described above, the same reference numerals are given and the detailed description is omitted.

FIGS. 9 and 10 show an embodiment of an apparatus provided with an electromagnetic coil and a dummy plate. The apparatus of the embodiment shown in FIGS. 7 and 8 and the embodiment of FIGS. It has a structure provided with a dummy plate 6 similar to that shown. Since other configurations are the same as those of the embodiment described above, the same reference numerals are given and the detailed description is omitted. FIGS. 11 and 12 show an embodiment of an apparatus having an adhesion amount control roll incorporating an electromagnetic coil. An electromagnetic coil 31 is incorporated in a portion of the adhesion amount control roll 5 facing the strip edge portion. ing. The electromagnetic coil 31 applies an electromagnetic field to the plated metal near the strip edge to control its flow. Each of the electromagnetic coils 31 is divided into a plurality of parts (not shown) in the strip width direction, and is configured such that the electric power applied to each divided coil can be individually controlled.

Gas spraying means (spraying) which can supply gas to the bath surface near the strip pass line on both sides of the strip pass line above the plating bath surface without providing the cover 7 as in the above embodiments. Nozzle etc.) can also be provided. Further, the adhesion amount control roll 5 is not necessarily a smooth roll. For example, a roll having appropriate irregularities or other additional elements on the surface for the purpose of positively forming a roll accompanying flow may be used. Good. Also, for the purpose of providing a difference between the roll entrainment flow at the center and the edge of the strip or to change the roll entrainment flow at an appropriate gradient in the strip width direction, an appropriate crown is provided on the roll. You may.

Next, the operation of the apparatus of each embodiment described above will be described. In the apparatus of each embodiment, the strip S entering the hot-dip galvanizing bath 1 from the snout 15 was turned upward by the sink roll 2, and the pass line was adjusted and the shape was corrected by the stabilizing roll 3 and the collecting roll 4. Thereafter, the excess plating is drawn out of the bath after passing between the pair of adhesion amount control rolls 5, and the excess plating adhered by the ejection of the wiping gas from the gas wiping nozzle 9 is scraped off.

The amount of the plating metal lifted from the plating bath 1 by the strip S is preferably as small as possible to reduce the excess plating metal scraped off by the gas wiping in order to suppress the occurrence of splash during gas wiping. For this reason, the adhesion amount control roll 5 adjusts and controls the gap and the rotation speed with the strip S so as to obtain a predetermined roll accompanying flow, and the roll accompanying flow generated thereby causes the strip S to accompany the strip S on the bath surface. Adjust the amount of plated metal that can be lifted. The flow accompanying the roll due to the rotation of the coating amount control roll 5 acts to reduce the amount of plating metal lifted along with the strip S, and therefore,
In the case of thick coating or the like, the adhesion amount control roll 5 may be in a non-rotating state. As described above, the rotation / non-rotation of the adhesion amount control roll 5 is selected as necessary, and when the roll is rotated, by controlling the rotation speed of the roll and adjusting the gap with the strip, the roll accompanying flow is controlled. By controlling the amount of plating metal lifted along with the strip S, the amount of excess plating metal lifted by the strip S can be reduced. As a result, the jet flow velocity of the wiping gas can be reduced, and the generation of splash can be suppressed.

In the apparatus shown in FIGS. 1 and 2 in which the dummy plates 6 are arranged near both edges of the strip S, as shown in FIG. Since the strip edge portion to be increased is replaced by the dummy plate 6, the edge portion of the strip S is not significantly affected by the inflow of the plating metal from both sides in the strip width direction. The amount of plating metal lifted accordingly becomes uniform in the strip width direction.

In the apparatus shown in FIGS. 3 and 4 provided with the plating metal suction nozzle 10, the plating metal near the strip edge is sucked and removed by the suction nozzle 10, thereby lifting up the strip S with the strip S. The amount of plated metal to be obtained can be made uniform in the strip width direction. Also, the suction nozzle 10 sucks and removes the plating metal near the strip edge, so that the amount of plating metal lifted along with the strip can be reduced on the edge side compared to the center of the strip, In this case, a uniform weight per unit area in the strip width direction can be obtained by wrapping the plated metal at the center of the strip toward the edge during gas wiping (using the principle of edge overcoating).

Since the suction nozzle 10 is movable in the strip width direction, it can always be placed at a position facing the strip edge regardless of the strip width. 5 and 6 provided with the dummy plate 6 and the suction nozzle 10, the suction nozzle 10 is used to supplement the operation of the dummy plate 6. 7 and 8 including the electromagnetic coil 30 for controlling the flow of the plating metal, the electromagnetic field generated by the electromagnetic coil 30 applies a magnetic pressure to the plating metal near the edge of the strip S. It is possible to prevent a plating metal flow from flowing into the strip edge portion, thereby making it possible to equalize the amount of plating metal lifted along with the strip in the strip width direction.

Also, by applying an electromagnetic field that generates a plating metal flow in the opposite direction to the plating metal flow Z as shown in FIG. 16 by the electromagnetic coil 30, the plating metal flow flowing outward from the strip edge portion is prevented. In this case, the amount of plating metal adhering to the strip edge portion side can be made smaller than that in the center portion of the strip, so that the plating metal in the center portion of the strip wraps around the edge portion side during gas wiping. By using the principle of the edge overcoat, a uniform basis weight can be obtained in the strip width direction. Since the electromagnetic coil 30 is movable in the strip width direction, it can always be placed at a position facing the strip edge regardless of the strip width.

9 and 10 in which the dummy plate 6 is arranged near both edges of the strip S together with the electromagnetic coil 30, the action of the dummy plate 6 is supplemented by the action of the magnetic pressure by the above-described electromagnetic coil 30. Will be In the apparatus shown in FIGS. 11 and 12 having the adhesion control roll 5 having the built-in electromagnetic coil 31, the amount of plated metal lifted along with the strip is made uniform in the strip width direction by the action of the electromagnetic coil 31 similar to that described above. Can be changed. Also, the electromagnetic coil 31 in the roll
Is divided into a plurality of parts, and by changing the applied power to each divided coil in accordance with the position of the strip edge, a magnetic pressure corresponding to the change in the strip width can be obtained. Appropriate control of the metal flow is possible.

FIG. 14 shows the effect of preventing the edge overcoat when the apparatus of the present invention is used, in comparison with the case of using the conventional apparatus. By using the apparatus of the present invention, the edge overcoat of the strip can be reduced. It turns out that it can be reduced effectively. Further, a non-oxidizing gas such as an inert gas or a weak oxidizing gas or a reducing gas having a low oxygen concentration is supplied to the inside of the cover 7 covering the bath surface of each embodiment through the gas supply means 8. Are kept in these gas atmospheres. As a result, since the bath surface is prevented from being disturbed by the wiping jet from the gas wiping nozzle 9 located above, the amount of plated metal lifted along with the strip S is not uniform in the strip width direction. Is prevented. Further, the oxidation of the plating metal on the plating bath surface is prevented, and the oxidizing gas (air) is not sucked into the plating metal suction nozzle 10.
Oxidation of the plating metal sucked to zero is also prevented. In addition,
When a non-oxidizing gas is supplied, the oxygen concentration is preferably regulated to less than 5% in order to prevent oxidation of the plating metal.

In particular, when the wiping gas is air,
A large amount of oxide is contained in the scraped-down plating metal, which may flow into the cover or oxidizing gas may enter to oxidize the plating metal attached to the strip. Therefore, in this case, by supplying a reducing gas to the inside of the cover 7 and setting the inside of the cover 7 to a reducing gas atmosphere, oxidation of the plated metal can be prevented, and the inflowing oxide is reduced. This prevents the oxidized plating metal from adhering to the strip S.

[0046]

As described above, according to the apparatus of the present invention,
The amount of plating metal lifted along with the strip can be freely controlled by the adhesion amount control roll, and the amount of excess plating metal lifted by the strip can be reduced as compared with the conventional apparatus. For this reason, the jet flow velocity of the wiping gas can be reduced, and the generation of splash can be suppressed.

Further, in an apparatus in which a dummy plate adjacent to both edges of the strip is arranged together with the adhesion amount control roll, the amount of plating metal lifted along with the strip can be made uniform in the strip width direction. Along with reducing the amount of excess plating metal by the control roll, a uniform plating weight in the strip width direction can be obtained. In addition, in an apparatus provided with a plating metal suction nozzle together with the adhesion amount control roll, the suction nozzle suctions the plating metal near the strip edge,
By eliminating the strip, the amount of plated metal lifted along with the strip can be made uniform in the strip width direction. For this reason, the uniform amount of plating can be obtained in the strip width direction in combination with the reduction of the amount of excess plating metal by the adhesion amount control roll.

The suction nozzle sucks and removes the plating metal in the vicinity of the strip edge, so that the amount of plating metal lifted along with the strip is reduced on the edge side compared to the center of the strip, and the gas is removed. By wrapping the plating metal at the center of the strip toward the edge during wiping, a uniform plating weight in the strip width direction can be obtained. Further, since the amount of excess plating metal at the strip edge portion before the gas wiping can be reduced, the jet flow velocity of the wiping gas can be reduced accordingly, and the generation of splash can be more effectively prevented. Therefore, in the apparatus provided with the dummy plate and the suction nozzle together with the adhesion amount control roll, the action of the dummy plate described above can be supplemented by the suction of the plating metal near the strip edge by the suction nozzle, so that the plating in the strip width direction is performed. The basis weight can be made more uniform.

Further, in an apparatus provided with an electromagnetic coil for controlling the flow of plating metal together with the adhesion amount control roll, a magnetic pressure is applied to the plating metal near the strip edge by an electromagnetic field generated by the electromagnetic coil. In addition, it is possible to prevent a plating metal flow from flowing into the strip edge portion, thereby making it possible to equalize the amount of plating metal lifted along with the strip in the strip width direction. For this reason, the uniform amount of plating can be obtained in the strip width direction in combination with the reduction of the amount of excess plating metal by the adhesion amount control roll. Therefore,
In the device in which the dummy plate and the electromagnetic coil are provided together with the adhesion amount control roll, the above-described operation of the dummy plate can be supplemented by the operation of the electromagnetic coil, so that the plating basis weight in the strip width direction can be made more uniform. it can.

Also, by applying an electromagnetic field which generates a plating metal flow in a direction opposite to the plating metal flow Z as shown in FIG. 16 by the electromagnetic coil, a plating metal flow flowing outward from the strip edge portion is generated. In this case, the amount of plating metal adhering to the strip edge portion side can be made smaller than that in the center portion of the strip, so that the plating metal in the center portion of the strip wraps around the edge portion side during gas wiping. Thereby, a uniform basis weight can be obtained in the strip width direction. Further, since the amount of excess plating metal at the strip edge portion before the gas wiping can be reduced, the jet flow velocity of the wiping gas can be reduced accordingly, and the generation of splash can be more effectively prevented.

Further, in the apparatus having the adhesion amount control roll having a built-in electromagnetic coil, the amount of plated metal lifted along with the strip by the action of the same electromagnetic coil as described above can be made uniform in the strip width direction. ,
Along with reducing the amount of excess plating metal by the adhesion amount control roll, it is possible to obtain a uniform plating basis weight in the strip width direction.

Gas blowing means is provided on both sides of the strip pass line on the plating bath surface, and the bath surface near the strip pass line is provided with a non-oxidizing gas such as an inert gas or a weakly oxidized gas having a low oxygen concentration from the gas blowing means. By supplying the neutralizing gas or the reducing gas, oxidation of the plating metal sucked by the bath surface or the suction nozzle can be prevented. Further, a cover for covering a bath surface through which the strip pass line passes is provided, and a non-oxidizing gas such as an inert gas or a weak oxidizing gas or a reducing gas having a low oxygen concentration is supplied from a gas supply means inside the cover, By keeping the inside in these gas atmospheres, it is possible to prevent the bath surface from being disturbed by the wiping jet and to prevent the amount of plated metal lifted by the strip from becoming uneven in the strip width direction. It is possible to prevent oxidation of the plating metal sucked by the bath surface or the suction nozzle, and also prevent the oxidized plating metal from adhering to the strip.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing one embodiment of a hot-dip metal plating apparatus of the present invention.

FIG. 2 is a side view of the hot-dip metal plating apparatus shown in FIG.

FIG. 3 is a longitudinal sectional view schematically showing another embodiment of the hot-dip metal plating apparatus of the present invention.

FIG. 4 is a side view of the hot-dip metal plating apparatus shown in FIG.

FIG. 5 is a longitudinal sectional view schematically showing another embodiment of the hot-dip metal plating apparatus of the present invention.

FIG. 6 is a side view of the hot-dip metal plating apparatus shown in FIG.

FIG. 7 is a longitudinal sectional view schematically showing another embodiment of the hot-dip metal plating apparatus of the present invention.

8 is a side view of the hot-dip metal plating apparatus shown in FIG.

FIG. 9 is a longitudinal sectional view schematically showing another embodiment of the hot-dip metal plating apparatus of the present invention.

FIG. 10 is a side view of the hot-dip metal plating apparatus shown in FIG.

FIG. 11 is a longitudinal sectional view schematically showing another embodiment of the hot-dip metal plating apparatus of the present invention.

FIG. 12 is a side view of the hot-dip metal plating apparatus shown in FIG.

FIG. 13 is an explanatory view showing the operation of the dummy plate shown in FIGS. 1 and 2 and the like.

FIG. 14 is a graph showing the effect of preventing edge overcoat when the device of the present invention is used, in comparison with the case of using the conventional device.

FIG. 15 is an explanatory view showing an operation of a rotating roll disposed below a bath surface of a plating bath.

FIG. 16 is an explanatory diagram showing a plating metal flow in a strip width direction caused by an entrainment flow of the rotating roll shown in FIG. 15;

FIG. 17 is an explanatory view showing the operation of the electromagnetic coil.

FIG. 18 is an explanatory view showing a conventional edge overcoat prevention method.

FIG. 19 is an explanatory view showing a conventional edge overcoat prevention method.

FIG. 20 is an explanatory view showing a conventional edge overcoat prevention method.

FIG. 21 is an explanatory view showing a conventional edge overcoat prevention method.

FIG. 22 is an explanatory view showing a conventional edge overcoat prevention method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hot dip galvanizing bath, 2 ... Sink roll, 3 ... Stabilizing roll, 4 ... Collecting roll, 5 ... Adhesion amount control roll, 6 ... Dummy plate, 7 ... Cover, 8
... gas supply means, 9 ... gas wiping nozzle, 10 ... suction nozzle, 30, 31 ... electromagnetic coil, 71 ... slit,
72 ... Cover upper surface

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshihide Kawano 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (56) References JP-A-55-128570 (JP, A) JP-A-3 -87345 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 2/00-2/40

Claims (10)

(57) [Claims] 1. A shallow positions under the bath surface of the molten metal plating bath
And roll rotation between hot metal plating bath surface
Creates a bath space for the flow of the accompanying molten metal
A hot-dip metal plating apparatus comprising a pair of adhesion control rolls for controlling the amount of plating metal deposited on a strip at a position where the strip can be cut in parallel with the strip width direction with a strip pass line interposed therebetween. 2. A dummy plate is provided at least in a range close to and below a bath surface of a hot-dip metal plating bath so as to be close to both edges of a strip to be passed and substantially flush with the strip. Placed at a shallow position below the bath surface of the hot-dip metal plating bath, and
Bath for the flow of molten metal accompanying roll rotation between
A pair of adhesion amount control rolls for controlling the amount of adhesion of the plating metal to the strip are provided at a depth position where a space can be formed in parallel with the strip width direction including the dummy plate with the strip pass line interposed therebetween. Metal plating equipment. 3. The hot-dip metal plating apparatus according to claim 1, wherein the adhesion amount control roll is configured to be able to adjust a gap with the strip pass line. 4. The method according to claim 1, wherein suction means for sucking plating metal near both edges of the strip to be passed is provided at a shallow position below the bath surface of the molten metal plating bath. Hot-dip metal plating equipment. 5. The hot-dip metal plating apparatus according to claim 4, wherein the suction means for the plating metal is configured to be movable in the strip width direction. 6. An electromagnetic coil for providing an electromagnetic field for controlling a plating metal flow near both edges of a strip to be passed near a bath surface or at a shallow position below the bath surface in a molten metal plating bath. 4. The hot metal plating apparatus according to 2 or 3. 7. The coated amount control roll includes an electromagnetic coil for providing an electromagnetic field for controlling a plating metal flow near both edges of a strip to be passed.
2. The hot-dip metal plating apparatus according to 1. 8. The hot-dip metal plating apparatus according to claim 6, wherein the electromagnetic coil is configured to be movable in a strip width direction. 9. A gas blowing means for blowing gas to the bath surface near the strip pass line is provided on both sides of the strip pass line above the bath surface of the molten metal plating bath. , 6, 7 or 8. 10. A cover for covering a bath surface through which a strip pass line of a molten metal plating bath passes, and gas supply means for supplying gas to the inside of the cover are provided.
The hot-dip metal plating apparatus according to 4, 5, 6, 7, or 8.