JPH09195028A - Hot dip plating equipment - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a hot dip plating apparatus capable of cleaning the surface of a steel sheet, forming a uniform plating layer, increasing the steel sheet moving speed, and improving workability and mass productivity. SOLUTION: The flux tank 1 in which the floating flux 18 that floats when the steel sheet 17 to which the flux is applied is immersed in a plating bath 19 is collected, and the inside is sealed with a non-oxidizing gas.
In the hot dipping apparatus A equipped with 2, the flux tank 1
A throat 20 arranged in the charging portion 12a of the second steel plate 17, surrounding the steel plate 17 to be charged and having a predetermined length, and a non-oxidizing gas for blowing a non-oxidizing gas to the steel plate 17 passing through the throat 20. And a spraying means 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot dip coating apparatus using a flux method, and more particularly to a hot dip coating apparatus capable of preventing the floating flux from deteriorating over time, having a high production yield and capable of cleanly plating the surface of a steel sheet.

[0002]

2. Description of the Related Art The applicant of the present invention previously disclosed in Japanese Patent Laid-Open No. 61-2175
In Japanese Patent Laid-Open No. 65-65, while a flux is applied to a steel plate that continuously runs, the steel plate is immersed in a plating bath,
A method for producing a continuous hot-melt Pb-Sn alloy-plated steel sheet using a so-called flux method was presented. A method of hot-dip plating a steel sheet using the hot-dip galvanized steel sheet manufacturing facility B will be described with reference to FIG. First, the steel plate 81 moves continuously between the uncoiler 31 and the coiler 72 at a constant speed, and during that time, a predetermined operation is performed in each step. The steel plate 81 obtained by joining the steel plates annealed by the welding machine 32 is passed through the front looper 33, the surface of the steel plate 81 is cleaned by the pretreatment device B1, and then the pre-electroplating and the application of the pre-flux are performed.

The pretreatment device B1 is a degreasing device 34 for removing oils and organic components adhering to the surface of the steel plate 81, a scrubber 35, a water washing device 36, and dissolves oxides formed on the surface of the steel plate 81. Separated pickling device 37, water washing device 38, pre-electroplating device 39, and water washing device 40
And a pre-flux bath 41. Next, the steel plate 81
A hot-dip plating apparatus B2 forms a plating layer by the hot-dip plating method. The hot dip plating device B2 is a flux coating device 51 that coats a flux of ZnCl ₂ aqueous solution or the like on the surface of a steel plate, a plating pot 52 that holds the plating bath 83 at 360 to 400 ° C., and a steel plate 81 immersed in the plating bath 83. The hot roll 53 to be driven, the discharging device 54 for sucking the floating flux 82 accumulated in the charging portion of the steel plate 81 on the surface of the plating bath 83, and the basis weight adjustment for adjusting the amount of the plating layer formed on the surface of the steel plate 81. And device 55. The steel plate 81 on which the plating layer is formed is cooled by the cooling device 61 and then subjected to post-treatment. In the post-processing device B3,
The steel plate 81 is quenched by the quench device 62, the surface of the steel plate 81 is chemically treated by the chemical treatment device 63, and then passes through the washing tank 64 and the drying device 65 to complete the operation. In FIG. 6, reference numeral 71 indicates a rear looper.

In the above hot dipping apparatus B2, the floating flux 82 is in direct contact with the atmosphere, so that the floating flux 82 deteriorates. Therefore, in order to solve this problem, the present applicant has filed Japanese Patent Application No. 7-20371.
As No. 0, a method for producing a hot dip plated steel sheet was proposed in which a floating flux was floated on a plating bath of a molten Zn-Sn alloy or a Pb-Sn alloy and the oxygen concentration on the floating flux was 1% or less. FIG. 8 is a sectional view of a main part of a hot dipping apparatus C that can be suitably used in the method according to FIG. 7. Figure 7
As shown in FIG. 1, the hot dip galvanizing apparatus C includes a flux applying apparatus 11 for applying flux such as ZnCl ₂ aqueous solution to the surface of the steel sheet 17, a lower surface in contact with the plating bath 19 and the steel sheet 17
Box-shaped flux tank 12 with an opening 12a
A non-oxidizing gas introduction hole 13 perforated in the flux tank 12, and an exhaust device 14 for removing the floating flux 18 accumulated on the surface of the plating bath 19 in the flux tank 12,
It comprises an oxygen detector 15 for measuring the oxygen concentration inside the flux tank 12, and a hot roll 16 for immersing the steel plate 17 in the plating bath 19.

Next, a method of hot-dip-plating a steel sheet by using the hot-dip galvanizing apparatus C having the above-mentioned structure will be described with reference to FIG.
This will be described with reference to FIG. First, the flux is applied to the surface of the steel sheet 17 by the flux applying device 11. The steel sheet 17 to which the flux has been applied is loaded into the flux tank 12 from the loading portion 12a and then immersed in the plating bath 19. Part of the flux applied to the steel plate 17 is the steel plate 17
Is separated from the steel plate 17 when immersed in the plating bath 19 and deposited on the surface of the plating bath 19. The steel sheet 17 has improved wettability with the molten metal in the plating bath 19 due to the action of the flux, and can make good contact with the molten metal. A non-oxidizing gas such as nitrogen gas is introduced into the flux tank 12 through the non-oxidizing gas introducing hole 13 and is replaced with air.

[0006]

However, the above-mentioned hot dip plating apparatus still has the following problems to be solved. That is, in the hot dipping apparatus B2 described in Japanese Patent Laid-Open No. 61-217565, when a water-soluble flux is used, the applied amount of the flux applied to the steel sheet is large and the molten metal does not uniformly adhere to the product quality. Is not stable and the manufacturing yield is reduced. Also,
Even if the amount of flux applied is appropriate, depending on the steel plate, the water in the flux may come into contact with the molten metal in the plating bath and the bumping may occur in the plating bath if the rate of immersion in the plating bath increases. By this bumping, a new surface of the molten metal is generated and reacts with oxygen in the atmosphere to generate an oxide. Even when the flux is not water-soluble, when the velocity of the steel sheet that penetrates the plating bath of the steel sheet increases, air enters the interior of the plating bath due to the impact during movement, and the oxygen in the air reacts with the molten metal. Similarly, an oxide is formed. When these oxides are mixed in the floating flux on the plating bath surface, the floating flux is deteriorated and the viscosity of the floating flux becomes high. The scum composed of deteriorated floating flux is caught in the plating bath, bites between the hot roll and the steel plate in the plating bath, and is scratched on the steel plate or pulled up from the plating bath while being attached to the steel plate. As a result, the appearance deteriorates, the plating quality deteriorates, and the manufacturing yield also deteriorates. Further, in order to prevent this, the moving speed of the steel sheet must be slowed down, which causes a problem of poor workability and mass productivity. Also,
In the hot dipping apparatus C shown in FIG. 7, the above problems can be solved to some extent, but the charging part 12a of the steel plate into the flux tank 12 is used.
Air invades from the tank and the oxygen concentration in the flux tank 12 becomes 1
It is in the range of up to 1.5% and cannot be lowered sufficiently. Therefore, there is a problem that the molten metal in the plating bath and the floating flux are deteriorated so that the metal is still mixed in the plating bath.

The present invention has been made in view of the above circumstances, and a hot dipping apparatus capable of cleaning the surface of a steel sheet and forming a uniform plating layer, increasing the moving speed of the steel sheet, and improving workability and mass productivity. The purpose is to provide.

[0008]

According to the present invention, there is provided a semiconductor device comprising:
The hot dip coating apparatus described above collects a floating flux that floats when a steel sheet coated with flux is immersed in a plating bath, and the inside of the hot dip coating apparatus includes a flux tank sealed with a non-oxidizing gas, A throat disposed in the charging portion of the steel plate, surrounding the steel plate to be charged, and having a predetermined cross section and length, and a non-oxidizing gas spraying for spraying a non-oxidizing gas to the steel plate passing through the throat. And means. A hot-dip galvanizing apparatus according to claim 2 is the hot-dip galvanizing apparatus according to claim 1, wherein the non-oxidizing gas blowing means applies a non-oxidizing gas to the steel sheet at a blowing speed not less than a steel plate moving speed and not more than 50 m / s. To spray.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, referring to the attached drawings, an embodiment in which the present invention is embodied will be described to provide an understanding of the present invention. Here, FIG. 1 is a sectional view of an essential part of a hot dipping apparatus according to an embodiment of the present invention, and FIG.
Fig. 3 is a relationship diagram between the oxygen concentration inside the flux tank in the range of -21% and the deterioration flux adhesion rate. Fig. 3 is a relationship diagram between the oxygen concentration inside the flux tank in the range of 0.1 to 1% and the deterioration flux adhesion rate. Fig. 4 shows the relationship between the oxygen concentration inside the flux tank in the range of 0.1 to 21% and the product yield loss. Fig. 5 shows the oxygen concentration inside the flux tank in the range of 0.1 to 1% and the product yield loss. FIG. As shown in FIG. 1, the hot-dip galvanizing apparatus A has a throat 20 through which the steel sheet 17 passes when the hot-dip steel sheet 17 is charged and a non-oxidizing gas to the steel sheet 17 in addition to the hot-dip galvanizing apparatus C described with reference to FIG. 7. The structural feature is that the non-oxidizing gas spraying means 21 for spraying is added. The same components as those of the hot dipping apparatus C are designated by the same reference numerals and the description thereof will be omitted.
That is, in FIG. 1, the hot-dip galvanizing apparatus A includes a flux applying apparatus 11, a flux tank 12, a non-oxidizing gas introducing hole 13, an ejecting apparatus 14, an oxygen detector 15, a hot roll 16, and a throat 20. And a non-oxidizing gas spraying means 21.

In the above structure, the throat 20 is provided to prevent air from entering the inside of the flux tank 12 and reduce the oxygen concentration inside the flux tank 12. The non-oxidizing gas such as nitrogen gas blown onto the steel sheet 17 by the non-oxidizing gas blowing means 21 fills the inside of the throat 20 and moves from the inside of the flux tank 12 to the outside with a flow velocity. As a result, it is possible to block the entry of outside air into the throat 20. Further, the shape of the throat 20 has a rectangular cross section and the steel plate 1
It is preferable that the gap with 7 is about 1 mm.

The non-oxidizing gas blowing means 21 is provided to reduce the oxygen concentration inside the flux tank 12 together with the throat 20. The non-oxidizing gas spraying means 21 arranges nozzles on the upper and lower surfaces of the steel plate 17, respectively. By adjusting the spraying angle of the nozzle and the spraying speed of the non-oxidizing gas, the non-oxidizing gas is throat 20.
It is sprayed inside so that the non-oxidizing gas fills the inside of the throat 20. The angle θ of spraying the non-oxidizing gas to the steel plate 17 is preferably 0 <θ <90 °. The blowing speed of the non-oxidizing gas is higher than the moving speed of the steel plate and is 5
A value of 0 m / s or less is preferably used. Steel plate moving speed is 40
The range of up to 90 m / min is preferably used. As the spraying speed becomes lower than the steel plate moving speed, the amount of non-oxidizing gas sprayed onto the steel plate 17 is not sufficient, and air intrudes into the throat 20 from the outside to increase the oxygen concentration in the flux tank 12, which is not preferable. . Spraying speed is 50m
The flux applied to the steel sheet 17 is blown away as the value exceeds / s, and the flux on the steel sheet 17 decreases, so that the wettability between the steel sheet 17 and the molten metal when the steel sheet 17 is immersed in the plating bath 19 cannot be improved. There is a tendency and it is not preferable. The nozzle may have a slit-like shape having the width of the steel plate, or a circular or polygonal nozzle may be arranged in parallel along the width of the steel plate. The blowing pressure of the non-oxidizing gas is about 2 kg / cm ² .

As the plating bath 19, a Zn bath, a Sn bath,
A Zn-Sn bath, a Pb-Sn bath or the like is used. An inert gas such as nitrogen gas or argon gas is used as the non-oxidizing gas.

Next, a method of hot-dip-plating a steel sheet by using the hot-dip galvanizing apparatus A having the above-mentioned structure will be described with reference to FIG.
This will be described with reference to FIG. First, a flux such as a ZnCl ₂ aqueous solution is applied to the steel plate 17 using the flux applying device 11. Steel plate 17 coated with flux is throat 2
It is loaded into the flux tank 12 from 0 and immersed in the plating bath 19 as it is. The non-oxidizing gas spraying means 21 sprays a non-oxidizing gas such as nitrogen gas onto the steel plate 17 in the throat 20 to fill the inside of the throat 20 with the non-oxidizing gas and prevent air from entering from the outside. The steel sheet 17 dipped in the plating bath 19 is subjected to the action of the flux, so that the plating bath 19
Since the wettability with the molten metal is excellent, the surface of the steel sheet 17 can be uniformly coated with the molten metal. The discharging device 14 discharges the floating flux 18 accumulated on the plating bath 19 from the inside of the flux tank 12 and can keep the amount of the floating flux 18 deposited constant. The non-oxidizing gas is introduced from the non-oxidizing gas introducing hole 13 into the flux tank 12, and the oxygen concentration in the flux tank 12 is lowered together with the throat 20 and the non-oxidizing gas blowing means 21. Oxygen detector 1
An oxygen concentration measuring sensor 5 and its display device 5 detect the oxygen concentration in the flux tank 12 to monitor whether it is controlled to an appropriate value.

Next, regarding the relationship between the oxygen concentration inside the flux tank, the adherence rate of deteriorated flux and the product yield loss,
This will be described with reference to FIGS. The deteriorated flux adhesion rate means the ratio of the adhered area of the deteriorated flux adhered per 1 m ^{2 of the} surface area of the steel sheet. Further, the product yield loss refers to the ratio of the length of the steel plate removed by the bite flaw to the entire length of the steel plate. As shown in FIG. 2 and FIG. 3, the deteriorated flux adhesion rate rapidly decreases from around the oxygen concentration of 1.5%. When the oxygen concentration is less than 1%, the deterioration flux adhesion rate becomes 0.24% or less, which is extremely low. Further, as shown in FIGS. 4 and 5, the product yield loss sharply decreases from the oxygen concentration of around 1.5%, and particularly when the oxygen concentration is less than 1%, the product yield loss is 0.4% or less. And extremely decreased. In the hot dipping apparatus A according to the present embodiment, the oxygen concentration in the flux tank 12 is set to 0.1 to 0.1%.
It is possible to suppress it to the range of 1%, and as a result, it is possible to reduce the adherence rate of the deteriorated flux to 0.24% or less and the product yield loss to 0.4% or less.
On the other hand, in the conventional hot dipping apparatus C shown in FIG. 7, the oxygen concentration in the flux tank 12 is 1 to 1.
It can be reduced only to the range of 5%, and the deterioration flux adhesion rate is about 0.24 to 0.7%, and the product yield loss is also in the range of 0.4 to 1%, and the value of the product yield loss is high. It is not possible to obtain stable quality products with large variations.

As described above, in the hot-dip galvanizing apparatus according to the present embodiment, the throat, which is disposed in the charging portion of the steel plate of the flux tank, surrounds the steel plate to be charged, and which has a constant length, and the throat. Since the non-oxidizing gas spraying means for spraying the non-oxidizing gas to the passing steel sheet is provided, the oxygen concentration inside the flux tank is 0.1 to 1.
%, And the oxidation of the molten metal in the plating bath can be reduced. As a result, the mixed amount of the molten metal oxide in the floating flux is small, and the deterioration of the floating flux can be prevented.

As described above, the present invention is not limited to the configurations described in the above-described embodiments, and other embodiments and modifications that can be considered within the scope of the matters described in the claims. Is included. For example, in the above-described embodiment, the throat is arranged on the upper surface of the flux tank, but it may be arranged on the side surface. Although the non-oxidizing gas blowing means is arranged inside the flux tank, it may be arranged below the throat.

[0017]

According to the hot-dip galvanizing apparatus of the present invention, the throat surrounding the steel sheet in the charging portion of the steel sheet in the flux tank, and the non-oxidizing gas for blowing the non-oxidizing gas to the steel sheet passing through the throat. Since the spraying means is provided, deterioration of the floating flux accumulated in the flux tank is reduced, and scum composed of the deteriorated floating flux can be prevented from being caught or attached to the surface of the steel sheet. as a result,
There are few defects on the steel plate and uneven thickness of the plating layer,
It is possible to obtain a high-quality hot dip plated steel sheet on which a clean and uniform plating layer is formed. Further, since the scum composed of the deteriorated floating flux is small, it is possible to increase the moving speed of the steel sheet and enhance the productivity. Furthermore, since the production yield is high and the production speed can be increased, mass productivity can be improved.

Particularly, in the hot dip galvanizing apparatus according to the second aspect, since the non-oxidizing gas spraying means sprays the non-oxidizing gas onto the steel sheet at a speed equal to or higher than the steel sheet moving speed and equal to or less than 50 m / s, the inside of the flux tank. It is possible to make the oxygen concentration of the extremely low value, to clean the surface of the steel sheet, to obtain a high quality product with a uniform coating amount, to increase the production yield, to increase the production speed, And productivity can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a hot dipping apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the oxygen concentration inside the flux tank and the deteriorated flux deposition rate in the range of 0.1 to 21%.

FIG. 3 is a diagram showing the relationship between the oxygen concentration inside the flux tank in the range of 0.1 to 1% and the deterioration flux attachment rate.

FIG. 4 is a relational diagram between oxygen concentration inside the flux tank in the range of 0.1 to 21% and product yield loss.

FIG. 5 is a relationship diagram between oxygen concentration inside the flux tank in the range of 0.1 to 1% and product yield loss.

FIG. 6 is an overall configuration diagram of a hot dip plated steel sheet manufacturing facility in JP-A-61-217565.

FIG. 7 is a cross-sectional view of a main part of a hot dipping apparatus in a conventional example.

[Explanation of symbols]

A hot dip coating apparatus 11 flux coating apparatus 12 flux tank 12a charging section 13 non-oxidizing gas introduction hole 14 discharging apparatus 15 oxygen detecting section 16 hot roll 17 steel plate 18 floating flux 19 plating bath 20 throat 21 non-oxidizing gas spraying means

Claims (2)

[Claims] 1. A hot dip galvanizing apparatus comprising a flux tank, in which floating flux that floats when a steel sheet coated with the flux is immersed in a plating bath is collected, and the inside is sealed with a non-oxidizing gas. A throat arranged in the charging portion of the steel plate, surrounding the steel plate to be charged, and having a predetermined cross section and length; and a non-oxidizing gas spraying means for spraying a non-oxidizing gas to the steel plate passing through the throat. A hot dip plating apparatus comprising: 2. The hot dip galvanizing apparatus according to claim 1, wherein the non-oxidizing gas spraying means sprays the non-oxidizing gas onto the steel sheet at a spraying speed not less than the steel plate moving speed and not more than 50 m / s.