JPH02129353A - Continuous hot dipping device - Google Patents

Abstract

PURPOSE:To obtain the title hot dipping device which need not be stopped when foreign matter is removed by providing a main snout whose tip can be pulled up from a plating bath and an auxiliary snout whose upper end is airtightly sealed by the main snout surface and whose lower part can be pulled up from the plating bath independently of the main snout. CONSTITUTION:The lower part 13 of the main snout 10 is lowered and dipped in a plating bath, and the lower part 23 of the auxiliary snout 20 is pulled up from the plating bath. A band steel 2 is sent into the plating bath through the upper part 11 of the snout 10 and the snout 20. As a result, the oxidation of the surface of the band steel 2 is prevented until the band steel is dipped into the plating bath. As plating procedures, the top dross formed on the plating bath surface in the snout 10 and the foreign matter coming from an annealing furnace 1 are floated on the bath surface. Accordingly, the lower part 23 of the snout 20 is dipped into the bath, then the lower part 13 of the snout 10 is raised, and the lower end is pulled up from the bath. Consequently, the inside is isolated from the outside of the snout 20, and the top dross and foreign matter are removed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a continuous hot-dip plating apparatus in which the entrance path of a copper strip entering a plating bath is blocked from the outside air by a duct called a snout. .

[Conventional technology]

When producing plated steel sheets using a continuous melt coating machine, the raw steel sheets are treated in an annealing furnace in a reducing atmosphere before plating in order to remove work hardening from the cold rolled steel sheets and purify the surface by reduction. becomes the norm.

In such a continuous hot-dip plating apparatus, as shown in FIG. 4. It is pulled out of the plating bath 7 through the snap roll 5, and the excess plating layer adhering to the surface is blown away by the nozzle 8 outside the bath, and the surface of the toning band 2 is plated to a predetermined thickness. . The snout 3 has an upper end connected to the outlet of the annealing furnace 1 and a lower end immersed in the plating bath 7.
The path of the steel strip 2 entering the plating bath 7 is blocked from the outside air, and the steel strip 2 is kept in a reducing atmosphere similar to that in the annealing furnace 1.
Prevents surface oxidation.

By the way, conventionally, in hot-dip galvanizing, a trace amount of Af has not been added to the plating bath for the purpose of improving the adhesion of zinc to the copper strip.

These A and f react with Fe precipitated from the strip to form Fe-Al, which is floated on the bath surface as so-called top dross. Furthermore, foreign matter carried from the furnace by the steel strip and zinc vapor in the snout also exist as floating foreign matter on the bath surface.

In the absence of a snout, these contaminants will spread over the bath surface and, even if concentrated near the point where the strip enters the plating bath, can be easily removed. However, if there is a snout, all of these foreign substances will be concentrated near the copper strip entry point into the bath, and may adhere to the copper strip just before plating, or as the strip enters the bath. It gets caught up in the bath and attaches to the steel strip moving through the bath. As a result, plating defects such as non-plating and indentation scratches due to adhesion of dross occur. Further, even if these foreign substances are removed from within the snout, the conventional technology cannot avoid operation interruption and gas replacement within the snout.

[Problem to be solved by the invention]

For example, in Japanese Patent Publication No. 63-49743, foreign matter in the snout is removed from the bath surface by lifting the snout slightly above the bath surface and removing foreign matter accumulated on the bath surface in the snout to the outside while circulating an inert gas through the snout. A method of removal is disclosed. According to this, there is no need to replace the inside of the snout with outside air conditions, no oxygen is sucked into the annealing furnace, and the removal work becomes easier, so the working time is certainly shortened.

However, it is still necessary to stop the line to remove foreign matter, and the use of inert gas inevitably increases costs. Lines have to be stopped twice a week in most cases to remove foreign matter, and this is a major factor hindering productivity.

The present invention has been made in view of this situation, and an object of the present invention is to provide a continuous hot-dip plating apparatus that does not require stopping the line or using an inert gas when removing foreign substances.

[Means to solve the problem]

The plating apparatus of the present invention is a continuous hot-dip plating apparatus in which the entrance path of the strip entering the plating bath is shielded from the outside air by a snout, and the main snout is configured such that its tip can be lifted out of the plating bath. is disposed inside the main snout and spaced apart from the inner surface thereof, the upper end is hermetically sealed against the inner surface, and the lower end is pulled up from the plating bath independently from the main snout. and a secondary snout configured to allow

[Function] In the plating apparatus of the present invention, when plating is performed with the tip of the main snout immersed in the plating bath and the tip of the sub-snout lifted from the surface of the plating bath, foreign matter is deposited on the surface of the plating bath in the main snout. The tip of the secondary snout is immersed in the plating bath at the zero point when the water accumulates, and then the tip of the main snout is lifted from the surface of the plating bath. Foreign matter remaining on the plating bath surface between the main snout and the sub snout is exposed to the outside. After removing the foreign matter exposed to the outside, the tip of the main snout is immersed in the plating bath, and after replacing the space between the main snout and the sub-snout with the furnace atmosphere gas, the tip of the sub-snout is lifted from the surface of the plating bath. By repeating this operation as necessary, the foreign matter in the snout is discharged to the outside while the steel strip approach path remains isolated from the outside air and without using inert gas.

(Example〕 The present invention will be described below with reference to Examples.

FIGS. 1 and 2 are a side view and a front view showing the structure of a main part (snout) of an example of a plating apparatus embodying the present invention.

The snout used in the plating apparatus of the present invention is composed of a main snout 1O and a sub-snout 20 provided inside the main snout 1O.

The main snout 10 is connected at its upper end to the outlet of the annealing furnace and is inclined at a predetermined angle. This main snout
O has a fixedly provided upper snout 11 and a lower snout 13 connected to the lower end of the upper snout 11 by a heat-resistant and airtight bellows 12.

Guide rods 14 whose lower ends are fixed to both sides of the lower snout 13 are slidably inserted into rod guides 15 provided in two stages at the lower end of the upper snout 11. With this guide mechanism, the lower snout 13 reciprocates in the vertical direction while maintaining a predetermined inclination angle, and due to this reciprocating movement, the lower end of the lower snout 13 is immersed in the plating bath and also raised above the plating bath surface. It will be done.

As a drive mechanism for moving the lower snout 13 in this manner, the lower end of a screw 16 is fixed to both sides of the upper surface of the lower snout 13, and the upper end of the screw 16 is fixed to both sides of the upper surface of the upper snout 11. Jack 1
7 is engaged.

A motor 18 provided on the side of one screw jack 17 simultaneously drives both screw jacks 17 using a rod 180 to reciprocate the lower snout 13 in the vertical direction.

Note that 19 is a gas replacement valve provided in the upper snout 11.

The sub snout 20 provided inside the main snout 10 is
The main snout 10 has the same inclination angle as the main snout 10.
A gap is formed around the entire circumference between the inner surface of the Like the main snout 1O, this sub-snout 20 also has an upper snout 21, a bellows 22, and a lower snout 23, and the upper end of the upper snout 21 is hermetically joined to the inner surface of the upper snout 11 of the main snout 20. .

The lower snout 23 has a dedicated guide mechanism and drive mechanism in the gap between the main snout 10 and the sub-snout 20 so that it can move up and down within the main snout 10 independently with respect to the upper snout 11. . These mechanisms themselves are the same as those provided in the main snout 10.

That is, it has a guide rod 24 and a front guide 25 as a guide mechanism, and a screw 26, a screw jack 27, a motor 28, and a rod as a drive mechanism, and these mechanisms cause the lower snout 23 to connect with the main snout 1o. While maintaining the same angle of inclination, the main snout 10
It reciprocates in the vertical direction independently of the lower snout 13 of
This reciprocating movement causes the lower end of the lower snout 13 to
The cross-sectional shapes of the main snout 1O and the sub-snout 20, which are immersed in the plating bath and lifted from the surface of the plating bath, need to be wide enough so that the sub-snout 20 does not hinder the movement of the copper strip passing through the inside. It is desirable to make the snout as wide as possible so that a sufficiently wide gap is formed between it and the sub-snout 20.

In the plating apparatus of the present invention having the snout as described above, the plating operation is performed according to the procedure shown in FIGS. 3(a) to 3(C).

During normal operation, as shown in FIG. 3(a), the lower snout 13 of the main snout 10 is lowered and its lower end is immersed in the plating bath, while the lower snout 23 of the secondary snout 20 is raised. , and leave it on standby with its lower end lifted out of the plating bath.

The steel strip 2 sent from the annealing furnace 1 passes through the upper snout 11 of the main snout 10, enters the sub snout 20,
Pass through here and enter the plating bath.

Inside the main snout 10, the lower end of the lower snout 13 is immersed in a plating bath and sealed, so the sub snout 20
The entire steel strip 2, including the inside, is maintained in the same reducing atmosphere as the inside of the annealing furnace 1, thereby preventing oxidation from occurring on the surface of the steel strip 2 before it enters the plating bath. Jinkroll 4
．． The steel strip 2 that comes out of the plating bath after passing through the snap roll 5 is
The excess plating layer is blown away by a nozzle 8 to form a plated steel plate with a predetermined plating thickness.

As the plating operation progresses, top dross is generated on the plating bath surface in the main snout 10, and foreign matter carried from the furnace or generated from metal vapor in the snout is also generated on the plating bath surface in the main snout 10. It's floating in the air.

These foreign substances occur to the extent that they affect the plating quality (
Then, as shown in FIG. 3(b), the main snout lO
With the lower end of the lower snout 13 still immersed in the plating bath,
The lower snout 23 of the sub snout 20 is lowered and its lower end is immersed in the plating bath. As a result, Deputy Snau l-2
The area above the connecting portion of the sub snout 20 inside the main snout 10 and inside the main snout 10 is cut off from the outside. With this in mind, 1. Third
As shown in Figure (C), the lower snout 13 of the main snout 10 is raised and its lower end is lifted above the plating bath surface. As a result of this lifting, foreign matter floating on the plating bath surface between the main snout 1O and the sub snout 20 is exposed to the outside. Even if foreign matter is exposed to the outside, the inside of the sub snout 20 remains isolated from the outside.

After removing the foreign matter exposed to the outside, first lower the lower snout 13 of the main snout 10 by reversing the above procedure, and
Immerse its lower end in the plating bath (see Figure 3 (bl)).
. As a result, the inside of the main snout 10 is again cut off from the outside. In this way, the main snout 10 and the secondary snout 20
Furnace atmosphere gas is blown into the space between the valve 19 and the furnace atmosphere gas, and after replacing this space with the furnace atmosphere gas, the lower snout 23 of the sub-snout 20 is raised and its lower end is lifted above the plating bath surface to return to the normal operating state. Return (see Figure 3 (a))
. The inside of the main snout 10 is insulated from the outside in advance, and the furnace atmosphere is maintained between the main snout 10 and the sub-snout 20, so even if the lower end of the sub-snout 20 is raised above the plating bath surface, the adjustment inside the snout will not occur. The travel path remains in the furnace atmosphere.

By raising the lower snout 23 of the secondary snout 20, the foreign matter floating on the inner plating bath surface is diffused throughout the main snout 10, reducing the dispersion density and affecting the plating quality. I won't give it anymore.

By performing the above operations appropriately during plating operations,
The dispersion density of foreign matter floating on the surface of the plating bath in the snout can be maintained at a level that does not affect the plating quality.

In addition, since the belt progression path inside the snout continues to be blocked from the outside, there is no need to interrupt the plating operation when removing foreign substances, there is no need to use inert gas, and there is no need to interrupt the plating operation. Furthermore, the surface of the steel strip will not be oxidized even if an inert gas is not used.

FIG. 4 is a sectional view showing another embodiment of the present invention.

In this embodiment, a plurality of nozzles 30 are provided in the strap width direction on the lower end of the lower snout 13 of the sub-snout 20 facing the wire belt, and the atmospheric gas in the annealing furnace l is discharged from the nozzles 30 during normal operation. Thus, foreign matter floating on the surface of the plating bath in the main snout 1O is collected near the inner surface of the main snout 1O.

By doing this, when the lower snout 23 of the secondary snout 20 is lowered to remove foreign matter (see Fig. 3 (+)), foreign matter will not enter therein and will not accumulate in the main snout 10 during normal operation. Most of the foreign matter is removed by the above-mentioned foreign matter removal.

Further, the gas discharged from the nozzle 30 is the atmospheric gas within the annealing furnace 1 and is not discharged outside the main snout 10, so that gas cost is unnecessary.

In the embodiment shown in FIGS. 1 and 2, a mechanism using screw jacks 17 and 27 is adopted as the drive mechanism for the lower snouts 13 and 23, but
The present invention is not limited to this, and for example, a rack and pinion or cylinder type may be used, and the guide mechanism is not limited to the above embodiment.

〔Effect of the invention〕

The continuous hot-dip plating apparatus of the present invention does not require stopping the line or using inert gas to remove foreign substances, and does not require stopping the line or using inert gas (but does not cause any quality problems). Therefore, the efficiency of plating operations is significantly improved, yield loss due to line stoppage is eliminated, and the expense required for removing foreign matter is also drastically reduced, making it possible to significantly reduce plating costs in these aspects.

Furthermore, foreign matter removal does not involve stopping the line and the cost is minimal, so foreign matter removal can be carried out frequently.
This also improves plating quality.

[Brief explanation of drawings]

1 and 2 are a side view and a plan view showing the main part (snout) of a plating apparatus embodying the present invention, and FIG. 3 (a)
) Φ) (C) is a side view showing the foreign matter removal procedure in the plating device of the present invention, FIG. 4 is a side view of a plating device showing another embodiment of the present invention, and FIG. 5 is a conventional plating device It is a side view which shows an example. In the figure, 2: rope, lO: main snout, 20: secondary snout. ! 1'j Figure Figure Figure Figure!

Claims (1)

[Claims] 1. A continuous hot-dip plating apparatus in which the entrance path of the steel strip entering the plating bath is shielded from the outside air by a snout, and the main snout is configured such that its tip can be lifted out of the plating bath, and the main snout is arranged inside the main snout at a distance from the inner surface thereof, and is configured such that the upper end is airtightly sealed against the inner surface and the lower end is raised from the plating bath independently of the main snout. A continuous hot-dip plating apparatus characterized in that it is equipped with a secondary snout.