KR20000043793A - Method and device for producing one-sided zinc-plated steel plate - Google Patents

Abstract

PURPOSE: A method and a device for producing one-sided zinc-plated steel plate are provided to obtain surface state of a steel plate and high plating efficiency. CONSTITUTION: An electric field of a polarity is formed between one face of a steel plate(12) passing through the inner of a plating tub(2) and a second charged electrode(5-2). Zinc powder is sprayed on one face of the steel plate. A first charged electrode(5-1) installed to correspond to the face of the steel plate is charged with the same voltage of the polarity as the electric field. The plated steel plate is reheated. Thereby, a one-sided zinc-plated steel plate is produced. Herein, the electric field formed between the second charged electrode and the steel plate is from 10kv/m to 200kv/m and the first electrode is charged with voltage from 1kv to 50kv. A zinc powder removal plate corresponding to both edges of the steel plate is installed in the position facing first and second electrodes in the plating tub and charged with voltage less than 100kv having a polarity different from the first charged electrode.

Description

Single-sided galvanized steel sheet manufacturing method and apparatus

The present invention relates to a method for manufacturing a single-sided galvanized steel sheet and a manufacturing apparatus thereof, and to a method for manufacturing a single-sided galvanized steel sheet having a plated layer formed on one side of a strip-shaped steel sheet and the other side having an unplated iron surface.

Recently, the demand for steel sheet has become more stringent due to the demand for high quality and high corrosion resistance of automobiles and home appliances. Especially, automobile and home appliance makers do not cause rust on the products along with the beautiful appearance of automobiles and home appliances. Does not require rust prevention. As the demands of automobile consumers, characteristics such as phosphate treatment, workability, surface appearance after painting, weldability and tooth resistance are required. In particular, the outer surface exposed to the outside of the outer surface of the steel sheet for outer plate should be suppressed the surface corrosion resistance, which means the swelling of the coating film, the hole corrosion resistance on the inner surface should be suppressed.

Among these required properties, the corrosion resistance of the hole in the steel sheet can be improved by the galvanized layer, but the remaining properties are known to show the excellent properties of the cold rolled steel sheet compared to the plated steel sheet. Therefore, if one side of both sides of the steel plate is galvanized and the other side is the steel plate, the one-side coated steel sheet is used as the outer plate of the car body and home appliances, and the iron surface is facing outward to satisfy all the characteristics required by the demand.

Techniques for producing single-sided galvanized steel sheets by electroplating and hot dip plating are known. Electroplating is a carousel process. In this process, the plating is performed in the process of turning the conductor mole while the steel sheet is in close contact with the cylindrical conductor mole, so that plating is performed only on the surface in contact with the plating solution. In this method, however, hydrochloric acid ions, which are important components of the plating solution, are adsorbed on the unplated surface during plating. Therefore, when the steel sheet is stored for a long time after production, the risk of rust on the unplated surface is very high.

As a method of producing single-side coated steel sheet by hot-dip plating method,

1) After plating, one side is removed by electrolytic method or mechanical grinding.

2) A method of preventing molten zinc from adhering to the non-plated surface when the steel sheet is deposited in the hot dip bath after pre-coating a material such as water glass on one side of the steel sheet before hot dip plating.

3) Only one side of the steel sheet is brought into contact with the hot dip bath.

4) A method of applying molten zinc to only one surface by a roll coating method or the like has been proposed.

In these methods, the method of 1) and 2) is very troublesome to remove the plating layer on one side after plating, and requires a great effort to remove it. In addition, the method of 3) and 4) requires very great care in order to attach the plating layer on only one surface, and also has difficulty in controlling the amount of plating.

Due to the above reasons, the method of producing single-sided plating by hot-dip plating has been developed from the late 1970s to the mid-80s. However, in all methods, manufacturing is difficult and work management is difficult. .

The present invention is to solve the above-mentioned problems occurring in the process of manufacturing a single-sided coated steel sheet, to provide a single-sided plated steel sheet manufacturing apparatus and a method of manufacturing the surface state of the steel sheet can be obtained and high plating efficiency. There is this.

The present invention for realizing the above object is located on one side of the plating bath to correspond to one surface of the steel plate to which the first and second charging electrodes connected to the first and second high voltage generators are transported, and the first and second charging electrodes An injection nozzle for injecting zinc powder toward one side of the steel plate is installed therebetween, and on one side of the plating bath, a grounded zinc powder removing plate corresponding to both edges of the steel plate is installed between the second charging electrode and the steel plate. An electric field of either polarity is formed, and the first charging electrode is charged with a voltage having the same polarity as the electric field formed between the second charging electrode and the steel plate.

In the present invention, an electric field having an intensity of 10 kW / m to 200 kW / m or less is formed between the second charged electrode and the steel plate, and a voltage of 1 kW to 50 kW is charged to the first charged electrode, and the zinc powder is removed. The plate is connected to the third high voltage generator and is charged with a voltage of 100 mA or less having a polarity different from that of the first charging electrode.

Method for producing a single-sided coated steel sheet using such a device comprises the steps of forming an electric field of any polarity between one surface of the steel sheet and the second charging electrode passing through the plating bath, and spraying zinc powder on one surface of the steel sheet And charging the first charging electrode installed in a state corresponding to one surface of the steel sheet with a voltage having the same polarity as that of the electric field, and reheating the plated steel sheet.

1 is a block diagram of a single-sided galvanized steel sheet manufacturing apparatus according to the present invention.

Figure 2 is a block diagram of another embodiment of one-side galvanized steel sheet manufacturing apparatus according to the present invention.

Hereinafter, with reference to the accompanying drawings of the present invention will be described in detail.

1 is a block diagram of an apparatus for manufacturing a single-sided galvanized steel sheet according to the present invention, in which the steel sheet 12 drawn out of the annealing furnace 1 is changed in direction by a deflector roll 11. 2) The interior and the reheating furnace (3) to pass through sequentially.

One side of the plating bath 2 is positioned to correspond to one surface (eg, the front surface) of the steel plate 12 to which the second charging electrode 5-2 connected to the second high voltage generator 8-2 is transferred. A zinc powder spray nozzle 7 is positioned below the charging electrode 5-2. The first charging electrode 5-1 connected to the first high voltage generator 8-1 is mounted inside or at the tip of the injection nozzle 7.

On the other hand, the zinc powder removing plate 4 is installed at another side of the plating bath 2, that is, the position facing the charging electrode 5-2 and the injection nozzle 7. Corresponds to another surface of the steel sheet 12 (for example, the rear surface of the steel sheet). The zinc powder removing plate 4 is grounded and is installed so as to correspond to both edge portions of the steel sheet 12.

As shown in FIG. 1, the steel plate 12 passes between the second charging electrode 5-2 and the zinc powder removing plate 4 in the plating bath 2. Referring to the process of manufacturing a single-sided galvanized steel sheet using the above-described single-sided galvanized steel sheet manufacturing apparatus as follows.

10 과정 between the second charging electrode 5-2 and the steel plate 12 connected to the second high voltage generator 8-2 while the steel sheet 12 passes through the plating bath 2 in an oxygen-free atmosphere. An electric field of positive or negative polarity with an intensity of / m to 1000 mW / m is formed. In addition, the zinc powder contained in the zinc powder storage tank 10 is supplied with nitrogen gas (supplied through a nitrogen gas pipe 9 connected to the zinc powder storage tank) to one surface of the steel plate 12 through the zinc powder injection nozzle 7. Sprayed).

On the other hand, the first high voltage generator 8-1 to which the first charging electrode 5-1 (which is mounted on the inside of the injection nozzle or the tip of the injection nozzle) positioned below the second charging electrode 5-2 is connected A high voltage having the same polarity as that of the second charging electrode 5-2 is generated to charge the first charging electrode 5-1 to a voltage of 1 kV to 50 kV. Then, the steel sheet 12 (with zinc powder attached to one surface) drawn out from the plating tank 2 is reheated in the reheating tank 3 at a temperature of 420 ° C to 600 ° C.

FIG. 2 is a schematic diagram of a device for manufacturing a single-sided galvanized steel sheet according to the present invention. Unlike FIG. 1, a third high voltage generator 13 is connected to a zinc powder removing plate 4, and a first charging electrode is provided. (5-1) was installed under the injection nozzle (7). Meanwhile, the zinc powder removing plate 4 connected to the third high voltage generator 13 is charged to a voltage of 100 kV or less having the opposite polarity with the second charging electrode 5-2.

Referring to the phenomenon occurring in the steel sheet during the process as described above is as follows.

When the zinc powder injected through the zinc injection nozzle 7 simply flows to the surface of the steel sheet 12 by nitrogen gas, it is difficult to uniformly adhere to the surface of the steel sheet 2 with high adhesion efficiency. Particularly, when the temperature of the steel sheet 12 is low, only the physical adsorption force acts, so that the adhesion efficiency of the zinc powder is further lowered. When the temperature of the steel sheet 12 is higher than the melting temperature of zinc, the zinc collided with the steel sheet 12 Although the powder may be melted by the latent heat possessed by the steel sheet 12 and the plating layer may be formed by the alloying reaction with the steel sheet, there is a great risk that the plating layer will be uneven if it is simply flowed by gas.

In the case of electrostatic charging of the zinc powder as in the present invention, in addition to the physical adsorption force, the electrical attraction acts to greatly improve the adhesion efficiency.

The adhesion efficiency is determined by the strength of the electric field and the amount of charge possessed by the zinc powder. Therefore, when the strength of the electric field is less than 10cm / cm, the electric field is too small, so that the effect of improving adhesion and uniformity is not sufficient, and if it is more than 1000㎸ / cm, the electric field is too strong and the space insulation is destroyed, causing the risk of arcing. It becomes big.

At this time, the polarity of electricity applied to the second charging electrode 5-2 has no problem in both the positive polarity (+) or the negative polarity (-), and the adhesion efficiency increases when the polarity is negative. The oxygen in the atmosphere gas moves to the steel sheet 12, so the risk of oxidizing the steel sheet increases, so it is necessary to completely remove the oxygen contained in the atmosphere gas. In the case of (+) polarity, the adhesion efficiency is (-). Although less than polar, there is an advantage that the risk of oxidation of the steel sheet is reduced.

The zinc powder injected to contact the electric field formed on the steel plate 12 and the second charging electrode 5-2 is electrostatically charged while passing through the electric field, and the electric field promotes adhesion to the steel plate. In order to produce a single-sided plating material, zinc powder should not be attached to the non-plated surface, but the risk that zinc powder, which is not attached to the steel plate and floats in the plating tank, will be attached to the non-plated surface. In particular, the electric field has a high risk of adhesion to both edge portions of the non-plated surface of the steel sheet due to a wrap around effect.

In the present invention, in order to solve this problem, the zinc powder removing plate 4 was installed at an appropriate distance in parallel with both edges of the steel plate 12, and the zinc powder removing plate 4 was electrically grounded (FIG. 1 state). ) Or when charged to a voltage of 100 kΩ or less having a polarity opposite to that of the second charging electrode 5-2 (FIG. 2 state), before the zinc powder scattered in the plating bath 2 adheres to the rear surface of the steel sheet 12. It is first attached to the zinc powder removing plate 4 and removed. At this time, when the zinc powder removing plate 4 is charged with electricity having the same polarity as that of the second charging electrode 5-2, the zinc powder is promoted to adhere to the unplated surface of the steel sheet 12. An electric field is formed between the secondary charging electrode 5-2 and the zinc powder removing plate 4 to reduce the zinc powder adhesion efficiency to the surface of the steel sheet 12.

As described above, when the zinc powder is electrostatically charged and plated, the zinc powder has a charge having the same polarity as that of the second charged electrode 5-2 before being affected by the electric field formed by the second charged electrode 5-2. When charged, the amount of charge that the zinc powders have increases, and thus the adhesion efficiency of zinc is further improved. At this time, the applied voltage is not effective at less than 1㎸, and if the voltage is increased more than 50㎸ does not show an improvement effect.

By reheating the steel sheet 12 with zinc powder in the reheating tank 3 in the same way as described above, it is changed to a complete plating layer. When the steel sheet temperature is 420 ° C. or less, the zinc powder is not changed into the plating layer, and at a temperature of 600 ° C. or more, the zinc-iron alloy layer grows, thereby causing poor plating adhesion.

EXAMPLE

Hereinafter, the present invention will be described in more detail with reference to the following examples.

The steel plate of 10cm width was continuously plated under the conditions of Table 1 and Table 2. When 90% of the zinc powder sprayed through the nozzle is attached to one side of the steel plate, the steel plate moves at a speed of 5 m / sec. The supply amount of zinc powder was set so that 100 g per m <^2> of the steel plate surface may be sprayed through a nozzle.

The effect of the present invention was evaluated in terms of the uniformity of the unplated and plated surfaces and the adhesion efficiency of zinc. The state of the non-plated surface was indicated by " (circle) " if the zinc powder was attached to both edges of the non-plated surface at 2 mm or less and " x "

The state of the plated surface was indicated by " (circle) " when the plating deposition amount variation was 10% or less, " Δ " when 10% or more and 20% or less, and " × "

In terms of plating efficiency, the amount of zinc powder adhered to the plated surface among the zinc powders injected was expressed as "○" when the amount of the zinc powder adhered to 90% or more, "Δ" when 50% to 90%, and "x" when less than 50%.

In the conditions outside the range defined in the present invention as in the comparative example in Table 1, the poor results in at least one of the non-plated surface state, the plating surface state and the plating efficiency was not obtained satisfactory results.

In the Example which satisfy | fills the limited range of this invention of Table 2, all the satisfactory results were obtained.

Secondary charging device Charging of metal plate 1st charging device Reheating Temperature (℃) Unplated Surface State Plated surface condition Gold polarity Electric field strength (㎸ / m) polarity Voltage polarity Voltage Comparative example One (+) 5 (-) 50 (+) 30 500 ○ ○ △ 2 (-) 5 (+) 50 (-) 30 500 ○ ○ △ 3 (+) 1500 (-) 50 (+) 30 500 ○ △ × 4 (-) 1500 (+) 50 (-) 30 500 ○ △ × 5 (+) 600 - none (+) 30 500 × ○ ○ 6 (-) 800 - none (-) 30 450 × ○ ○ 7 (-) 500 (+) 120 (-) 30 450 × ○ ○ 8 (+) 500 (+) 110 (+) 30 450 × ○ ○ 9 (-) 400 (-) 120 (-) 30 450 × ○ ○ 10 (-) 400 (+) 110 (-) 30 450 × ○ ○ 11 (-) 500 (+) 40 (+) 30 450 ○ × × 12 (+) 600 (-) 30 (-) 40 450 ○ × × 13 (-) 700 (+) 40 (-) 0.5 450 ○ △ △ 14 (-) 700 (+) 40 (-) 60 400 ○ × △ 15 (-) 700 (+) 40 (-) 30 650 ○ × ○

Secondary charging device Charging of metal plate 1st charging device Reheating Temperature (℃) Unplated Surface State Plated surface condition Gold polarity Electric field strength (㎸ / m) polarity Voltage polarity Voltage Example One (+) 15 (-) 50 (+) 30 500 ○ ○ ○ 2 (-) 25 (+) 50 (-) 30 500 ○ ○ ○ 3 (+) 900 (-) 50 (+) 30 500 ○ ○ ○ 4 (-) 950 (+) 50 (-) 30 500 ○ ○ ○ 5 (+) 600 - grounding (+) 30 500 ○ ○ ○ 6 (-) 800 - grounding (-) 30 450 ○ ○ ○ 7 (-) 500 (+) 100 (-) 30 450 ○ ○ ○ 8 (+) 500 (-) 100 (+) 30 450 ○ ○ ○ 9 (-) 400 (+) 20 (-) 30 450 ○ ○ ○ 10 (-) 400 (+) 30 (-) 30 450 ○ ○ ○ 11 (-) 500 (+) 40 (-) 30 450 ○ ○ ○ 12 (+) 600 (-) 30 (+) 40 450 ○ ○ ○ 13 (-) 700 (+) 40 (-) One 450 ○ ○ ○ 14 (-) 700 (+) 40 (-) 50 420 ○ ○ ○ 15 (-) 700 (+) 40 (-) 30 600 ○ ○ ○

The present invention as described above has a good surface state of the steel sheet and can obtain a high plating efficiency on one side, there is an effect that can be easily produced single-sided steel sheet.

Claims (4)

In the plating apparatus for passing the steel sheet drawn out to the annealing furnace sequentially through the inside of the plating bath and the reheating furnace, One side of the plating bath is positioned to correspond to one surface of the steel sheet to which the first and second charging electrodes connected to the first and second high voltage generators are transported, and zinc powder is applied to one surface of the steel sheet between the first and second charging electrodes. A spray nozzle for spraying is provided, and on one side of the plating bath, a zinc powder removing plate corresponding to both edge portions of the steel sheet is installed, and an electric field of any polarity is formed between the second charging electrode and the steel sheet. 1. The apparatus for manufacturing single-side galvanized steel sheet according to claim 1, wherein the charging electrode is charged with a voltage having the same polarity as the electric field formed between the second charging electrode and the steel sheet. In the manufacturing method of single-sided coated steel sheet, Forming an electric field of any polarity between one surface of the steel sheet passing through the plating bath and the second charging electrode; Spraying zinc powder on one surface of the steel sheet; Charging the first charging electrode installed in a state corresponding to one surface of the steel sheet with a voltage having the same polarity as the electric field; Single-sided galvanized steel sheet manufacturing method comprising the step of reheating the plated steel sheet. The method of claim 2, The electric field formed between the second charged electrode and the steel sheet is 10 kW / m to 200 kW / m, and the first charged electrode is charged with a voltage of 1 kPa to 50 kV single-sided plated steel sheet manufacturing method. The method of claim 2, At the position facing the first and second charging electrodes in the plating bath, a zinc powder removing plate corresponding to both edge portions of the steel sheet is installed to be charged at a voltage of 100 kV or less having a different polarity from that of the first charging electrode. Single-sided steel sheet manufacturing method characterized in that.