KR960007778B1 - Electroplating apparatus of radial shape and the method therefor - Google Patents

Abstract

This process is used for electroplating of zinc or another metal on the surface of metal strip(14). The plating device having not less than one cell consists of tank(1) containing salt bath or sulphate bath electrolyte(2), elastic polymer drum(18) with reeled metal strip(14), soluble or insoluble anode(23), nozzles(25, 26) for spray of electrolyte in inverse direction from circulating direction of strip(14) and drum(18), deflector roll(13) of elastic polymer, conductor roll(10) and back-up roll(11) for supply of cathode potential. The conductor roll(10) and back-up roll(11) is equipped for circulating in the parallel direction of drum shaft(9) between drum(18) and deflector roll(13). And the surface pollution of strip(14) on the deflector roll(13) prevents by removing of plating solution on the strip surface with conductor roll(10) and back-up roll(11) as mentioned above.

Description

Radial Electroplating Apparatus and Plating Method

1 is a block diagram showing a general radial electroplating apparatus.

FIG. 2 is a cross-sectional view showing both sides of FIG.

3 shows a) b) b) bonding of strips due to non-uniform profiles of conductor rolls.

4 is a cross-sectional view of an electroplating apparatus according to the present invention.

5 shows two continuous electrolytic cells provided in the electroplating apparatus of the present invention.

6 is a diagram showing a state in which the deprotor roller provided in the electroplating apparatus of the present invention is deformed.

* Explanation of symbols for main parts of the drawings

1: tank 2: electrolyte

5,14 strip 3,10 conductor roll

11: Back-up Roll 13: Deflector Roll

18 Drum 23 Anode

25,26: Nozzle

The present invention relates to an electroplating apparatus for metal strips <the plating method thereof, and more particularly to a radial plating apparatus for electroplating zinc or another metal on one surface of a metal strip, and to a method for manufacturing an electrogalvanized steel sheet using the same. It is about.

In general, the demand for plated metal sheets or coils demands, dimensional characteristics, and the variety of products for plating composition can provide the producers of plated products with excellent surface treatment steel sheet to guarantee high quality and to meet the demand characteristics. Pursuing a method and apparatus for manufacturing a coated steel sheet.

The plating apparatus and its manufacturing method according to the trend of this demand should be capable of producing a metal sheet including high-quality single-sided or double-sided plating composed of zinc alloys containing nickel or iron as well as pure zinc plating. The plated metal sheet should show a plated layer of uniform thickness with good dimension and mechanical properties. In particular, the metal sheet should not show band marks, arc spots, plating flow patterns, etc. due to conductor rolls that hinder the appearance quality of the product.

However, currently known electroplating apparatuses and methods do not meet the demand characteristics of such various demands.

Typical radial plating apparatuses are described in US Pat. Nos. 3,483,113 and 3,634,223.

The plating apparatus of the type described in the above patents is schematically illustrated in FIG.

These devices include a tank 1 comprising an electrolyte solution or a plating solution 2, a conductor roll 3 partially immersed in the plating solution, and an up-pass and a down-pass positioned to face each other on top of the tank 1. Down-Pass) deflector roll 4 or the like.

These devices also include a soluble anode (7) supported by the main anode (6), both the main anode (6) and the soluble anode (7) are immersed in the plating solution, and optionally a conductor to remove foreign matter. It may comprise a roll grinder 8 in contact with the roll 3. While the metal strip moves along the conductor roll 3, the plated metal is plated from the soluble anode 7 to the outside of the metal strip due to the electrical conduction.

The radial plating cell is particularly capable of plating only one side of the strip and is also useful for plating another metal on each of the strip faces. Such a structure of the conductor roll 3 is shown in FIG. The conductor roll 3 has a hollow metal cylinder 3a, a conductor ring 3b in the middle of the outer circumference of the metal cylinder 3a, and an elastomer lining 3c on both axes of the conductor ring 3b. It includes. In addition, the inside of the conductor roll is circulated with a coolant for absorbing Joule heat generated by the plating current in the direction of the arrow 3d.

In addition, when the metal strip moves along the conductor roll 3 of the above structure, the elastomeric lining 3c seals the opposite side edge of the strip to prevent the electrolyte from penetrating the inner surface thereof, thereby allowing one-side plating. Done. Therefore, the arrangement of the strip 5 in electrical contact with the conductor roll 3 is such that a large tension (hereinafter referred to as traction force) directed to the opposite side on both sides of the conductor roll 3 by applying sufficient pressure to the end of the conductor on the elastic side It should be pressurized in (5). The traction force is pressurized by deflector rolls 4 placed above the liquid level in the tank 1 to cause a constant deflection on the strips on both sides of the conductor roll 3. Thus, the elastomeric lining 3 should be corrosion resistant to the plating liquid and have sufficient elasticity and wear resistance to have a sealing function.

However, it is difficult to obtain an elastomer that meets all of these requirements, and during the actual plating operation, as shown in FIG. 2, a difference in thermal expansion coefficient and wear degree occurs between the conductor ring 3b and the elastomer lining 3c. Step S is generated.

If the conductor ring 3b is higher than the elastomer lining 3c, a band mark at the position of the step S, i.e., the conductor on the strip surface, as indicated by A in FIG. Elongation marks at both edges of the ring 3b appear, or if the traction is large, a deflection of the strip appears. On the contrary, if the conductor ring 3b is lower than the elastomer lining 3c, b) of FIG. In the step (S), as shown by B, the strip 5 cannot maintain sufficient contact with the conductor ring 3b, resulting in uneven plating, and the distribution of the electric field at both edges of the conductor ring 3b. By concentrating, an arc spot on the strip surface, i.e. electric heat, causes spot-like thermal defects where the strip surface burns locally.

In addition, the property of the strip is degraded because the large traction force wound on the strip which is wound on the conductor roll 3 generates a large mechanical stress in the body of the metal strip. In addition, efforts to improve the quality in the electroplating method by the radial plating cell as described above have been concentrated in the direction of improving the surface quality, such as the band mark and arc spot, and the mechanical properties of the strip, several improvements The effect is known.

Known techniques in this regard include US Pat. No. 5,069,762.

The present invention is to improve the electrical contact between the conductor roll and the metal strip, and to add the pressure roll in the horizontal direction to the conductor roll on the plating solution level to press the conductor in the center direction to prevent arc generation between the conductor roll and the metal strip. It is a way to suppress.

This method has a significant effect on the prevention of arc spots, but by adding a pressure roll to the conductor roll, it is not possible to suppress the occurrence of band marks by increasing the stress at the step between the conductor ring of the conductor roll and the elastomer lining. There is a problem.

Korean Patent Publication No. 3301 also discloses a related method, which is a technique in which a current is applied to a strip by a deflector roll disposed above a liquid level in a plating liquid tank.

This device has the advantage of suppressing the band mark by using a conventional roll of rubber, but there is an uneconomical problem in terms of power consumption because the current flows to the strip by the deflector roll separated from the anode.

The present invention is to solve the conventional problems as described above, the band mark and arc spot and mechanical properties during high-quality one-way plating or double-sided plating consisting of pure zinc, zinc alloy containing nickel or iron by radial plating cell It is an object of the present invention to provide a radial electroplating apparatus and a plating method thereof to prevent deterioration.

In order to achieve the above object, the present invention provides a tank containing a chlorinated bath or a sulfuric acid bath solution and an outer cylindrical shape of a drum immersed in the electrolyte solution and a rotating drum partially immersed in the electrolyte while winding a metal strip to be plated. Soluble anodes or insoluble anodes disposed opposite the surface, means for supplying current to the anodes, means for injecting electrolyte between the drums and the anodes in a countercurrent to the circulation direction of the strips and drums, and passing the electrolyte through the strips In the electro-zinc plating apparatus of a metal strip comprising a deflector roll set of an elastomer to induce a; and at least one cell consisting of a conductor roll and a back-up roll in contact with the strip between the deflector roll and the drum to supply a cathode potential. The conductor roll and the backup roll are disposed on both sides of the drum for each cell. A radial type electro galvanizing apparatus is provided, which is rotatably installed in a direction parallel to the air drum side, and at least partly, a deflector roll is installed at an upper level of the conductor roll and the backup roll. By

In addition, the present invention is a method for electroplating a metal strip in a device including a radial type cell for electroplating a metal strip, wherein the strip is wound on a deflector roll located above the electrolyte level and flows into the electrolyte. It is circulated in the electrolyte in contact with the surface of the drum lined with the insulating material and partially attached to the electrolyte on the opposite side of the active surface, and supplies a cathode current to the conductor roll and the backup roll side disposed between the drum lined with the insulating material and the deflector roll. By providing a method of electroplating a metal strip characterized in that.

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

4 shows a schematic view of an electrolytic cell of an electroplating tee according to the present invention.

The electrolytic cell includes a tank 1 containing an electrolyte solution or a plating solution 2. The tank 1 contains a plating liquid (Cl ⁻ ions or SO ₄ ²⁻ ions) 2 and an anode 23, the anode 23 having an bow-shaped segment consisting of an arc of an angle slightly smaller than 90 ^°. It is in the form of a segment and consists of a series of soluble anodes or insoluble anodes made of zinc or other metals.

The anode 23 is arranged laterally in a horizontal direction with the drum shaft 9 with a slightly smaller pore than 180 ^° to provide an active inner surface with some space from the rotating drum 18. The width of is composed of a cylindrical continuous active surface at least equal to the width of the plated strip. In addition, the anode 23 is divided into soluble anodes and insoluble anodes according to the type of the plating solution 2.

In the case of metal plating, in particular, in the case of electro zinc plating, the plating solution most commonly used is divided into a chloride bath (Cl ⁻ ) and a sulfate bath (SO ₄ ^2- ). If the plating solution 2 is a chloride bath, a soluble anode is applied; in the case of a sulfate bath, an insoluble anode is used.

The drum 18, whose diameter is somewhat smaller than the active interface of the anode 23, is rotatably mounted on the cell by the drum shaft 9, and the surface of the drum 18 is formed in a conventional radial cell. In the present invention, the drum is completely lined with elastomer, which is the same insulating material without the difference between the central part and both sides, while the material of the central part and both side parts is different, and there is a height difference (step difference). The in band mark and the mark spot are configured not to occur. Then, there is a predetermined space between the drum 18 and the anode 23, between which the nozzles 25 and 26 for the injection of the electrolyte are respectively located directly below the drum 18 and directly above the electrolyte level 15. It is removed and the electrolyte is sprayed in the direction opposite to the traveling direction of the strip 14.

The strip 14 wound on the drum 18 and passing through the electrolyte is pressed by the deflector roll 13 located on the upper sides of the drum 18. Between the deflector roll 13 and the electrolyte level 15, the conductive roll 10 made of steel connected to the negative electrode terminal, and the strip 14 into the plating cell together with the conductive roll 10 are formed. A backup roll 11 composed of an elastomer for guiding is disposed. In addition, the polishing machine 12 is attached to the surface of the conductor roll 10 to suppress the decrease in electrical conductivity to the strip due to surface contamination.

Reference numeral 17 is a power supply.

The electroplating process according to the present invention is carried out in the order of degreasing-pickling-electroplating.

In the pretreatment process, after the surface of the strip to be plated has been removed, or the oxide layer is removed, the strip 14 charged by the conductor roll 10 is in close contact with the drum 18 which is half immersed in the plating solution and continuously passes through the electrolyte. Plating takes place.

The anode 23 is roughly classified into a soluble and an insoluble anode according to its function. Soluble anode has the function of replenishing metal ions to be plated in addition to its role as a counter electrode, thus maintaining the plating solution concentration without additional plating replenishment. In addition, the soluble anode is made of the same metal as the plating layer, and the zinc anode is used for zinc plating, and the zinc and iron anode in the same proportion as the zinc or plating layer composition are used together in the zinc-iron alloy plating. The same concept applies to. However, alloy anodes are used only when selective dissolution of one element does not occur, and is rarely used for zinc-based plating, and is only used for alloys with similar dissolution potentials of both metals such as lead-tin. Insoluble anodes act as a counter electrode by generating oxygen-generating reactions, which can be used while maintaining a constant interpolar distance permanently depending on the management state.

The plating solution 2 is used for the sulfuric acid bath and hydrochloric acid. Sulfuric acid bath is advantageous for plating price, plating bath management, glossiness of plating surface, and rinsing property.In hydrochloric acid bath, electrical conductivity is about 1/2 of sulfuric acid bath, reducing plating power cost and increasing plating efficiency. Has the advantage. The plating solution is composed of different plating solutions depending on the metal plating in the process. Pure zinc (Zn) electrolytes are used only for pure zinc plating and contain ZnCl ₂ (ZnSO _{4 for} sulfuric acid baths), KCl (H ₂ SO _{4 for} sulfuric acid baths), HCl and the like. The electrolyte solution for Zn-Fe or Zn-Ni alloy plating contains Ni and Fe ion-containing solutions, respectively, for the chemical composition of the Zn electrolyte.

As described above, the present invention provides at least an electrolyte level between the drum 18 lined with a rotating elastomer and the deflector roll 13 for inducing strip propagation into the electrolyte while winding the strip to be partially immersed in the electrolyte. By disposing the conductor roll 10 and the backup roll 11 at a position higher than 15) and supplying a cathode current, all known points in the conventional radial plating cell can be solved.

Thus, the advantages of the present invention are the disadvantages of the known method for radial cells using conductor rings wound on drums, namely the degradation of the mechanical properties of the strips due to the large traction force on the strips and of the conductor rings and elastomer linings. Defects such as band marks and arc spots in the stepped portions can be prevented.

In addition, the present invention arranges the conductor roll 10 and the backup roll 11 between the drum 18 and the deflector roll 13 to bury the surface of the strip 14 as the strip 14 progresses from the plating cell. By removing the plating liquid, surface contamination of the strip 14 on the deflector roll 13 can be prevented.

The plating apparatus according to the present invention can use both a soluble anode-chloride bath system and an insoluble anode-sulfur salt bath system, and can increase productivity by increasing the circulation speed of the strip by arranging a plurality of cells.

As described above, the electroplating apparatus and the plating method according to the present invention can also easily control the production of the metal sheet plated on both sides by the same or different plating layer consisting of a zinc alloy layer or pure zinc layer containing iron or nickel. Can be.

In addition, the size, arrangement, and position of the conductor roll and the backup roll disposed in the present invention may be different from that described, and similarly, the electrolyte circulation in the annular zone disposed between the drum and the anode may be detected in a manner different from that described. Although all may be, they are included within the scope and spirit of the present invention.

Claims (6)

The tank 1 containing the chloride bath or the sulfuric acid bath solution 2 and the outer side of the drum immersed in the electrolyte and the rotating elastomer drum 18 partially immersed in the electrolyte while winding the metal strip 14 to be plated. Soluble anode or insoluble anode 23 disposed opposite the cylindrical surface, means 17 for supplying current to the anode, and strip 14 and drum 18 between the drum 18 and anode 23. Means 25, 26 for injecting the electrolyte solution in the counter-current direction with respect to the circulation direction of the &lt; RTI ID = 0.0 &gt;), a deflector roll 13 of elastomer, which induces passage of the electrolyte solution 2 through the strip 14, and the deflector roll 13. In the electro-zinc plating apparatus of a metal strip comprising at least one cell consisting of a conductor roll 10 and a backup roll 11 in contact with the strip 14 to supply a cathode potential between the drum and the drum 18. The conductor roll 10 and the back-up roll 11 are connected to the drum 18 for each cell. Disposed on both sides and rotatably installed in a direction parallel to the drum shaft (9), at least in part ensuring the retention of the strips (14) at the upper levels of the conductor roll (10) and the backup roll (11). Radial electroplating apparatus characterized in that the deflector roll 13 is mounted. The method of claim 1, wherein the conductor roll 10 and the back-up roll 11 is disposed at least on the electrolyte level 15, the radial type electric, characterized in that the mutual position can be changed with the strip 14 in between. Galvanizing equipment. 2. The deflector roll (13) according to claim 1, wherein the deflector roll (13) has an elastomeric material and is disposed at least two consecutively on top of at least the conductor roll (10) and the backup roll (11). Radial type electro zinc plating apparatus, characterized in that the diameter can be increased. In a method of electroplating a metal strip in an apparatus comprising a radial cell for electroplating a metal strip, the strip 14 is wound on a deflector roll 13 located above the electrolyte level 15 and introduced into the electrolyte. In contact with the surface of the drum 18, which is partially attached to the electrolyte and opposite to the active surface of the anode 23, contacts with the surface of the drum 18 lined with an insulating material, the drum 18 and the deflector roll 13 lined with the insulating material A radial type electro zinc plating apparatus, characterized in that the electroplating method of a metal strip, characterized by supplying a cathode current to the conductor roll (10) and the backup roll (11) side disposed between. 5. The radial type electro zinc plating apparatus according to claim 4, wherein the anode (23) can use both a soluble anode and an insoluble anode made of a plated metal. 5. The electroplating method of a metal strip according to claim 4, wherein the electrolyte solution (2) can use both a chloride bath and a sulfate bath.