KR20040034091A - A conductor roll for strip electroplating - Google Patents

Abstract

PURPOSE: A conductor roll for electroplating strip for improving plating quality is provided to effectively prevent band crease generated on a band edge part of the conductor roll by controlling height difference between steel band and rubber roll of the conductor roll and temperature of cooling water passing through the conductor roll. CONSTITUTION: In a conductor roll(1) for electroplating strip comprising an inner wall through which cooling water passes, and steel band(20) and rubber roll(30) respectively arranged on the outer side of the inner wall, wherein height difference (G) is formed between the steel band and the rubber roll, the conductor roll is characterized in that the height difference formed between the steel band and the rubber roll is 0.25 to 0.35 mm, temperature of cooling water passing through the inner wall of the conductor roll is 40 to 45 deg.C, and the rubber roll is formed of an ebonite material(30a) adjacent to the steel band, and a multilastic material(30b) on the outer side of the ebonite material.

Description

A CONDUCTOR ROLL FOR STRIP ELECTROPLATING}

The present invention relates to a conductive roll, a conductive roll, which is installed in a plating bath during electroplating to increase the corrosion resistance of a steel plate surface, and more specifically, to a step between a temperature of cooling water entering a cylindrical conductor roll and a steel band for energizing and a rubber roll as an insulator. By forming to a certain range, the present invention relates to a conductor roll for steel plate electroplating to improve the plating quality of the steel sheet by minimizing the generation of arc spots and band cracks caused by expansion between the steel band and the rubber roll to which the plated steel sheet is in close contact.

In general, the surface of the cold rolled steel sheet is subjected to electroplating such as pure zinc (Pure-Zn) or zinc-iron alloy (Zn-Fe), such electroplating of the steel sheet makes the surface of the steel sheet beautifully In order to increase the corrosion resistance of the steel sheet and to strengthen the wear resistance, and to provide other necessary surface properties if desired by the consumer, such an electroplating method may be performed by applying an electrode to an electrolyte (solution) containing metal ions. In this case, metal ions are discharged from the cathode and precipitated, and a thin film of metal is formed on the surface of the plated material placed on the cathode.

That is, the anode of the + electrode is arranged on the bridge in the plating cell filled with the electrolyte, and at a predetermined interval there is a cylindrical, that is, a carousel type having a steel band of the electrode and being wound and transported in close contact. Carosel Type) The conduit roll is disposed so as to be immersed in the electrolytic solution of the plating bath, and the metal ion of the anode is plated on the surface of the steel sheet, wherein the anode is a component to be plated, for example, pure zinc (Pure-Zn) Alternatively, in the case of zinc-iron alloy (Zn-Fe) plating, it is made of an iron anode, and in order to plate the front and rear surfaces of a steel sheet, a plurality of plating tanks are arranged on each plating line and continuously transferred to a feed roll. Surface electroplating will be carried out.

Meanwhile, FIG. 1 illustrates a conductor roll used in a conventional general electroplating line.

That is, as shown in Figure 1, the inner wall 10 structure of the conductor roll (1) is made of ordinary carbon steel (SS41) material, the steel sheet is in close contact with the center-high corrosion resistance steel band (Hastelloy) 20 is shrinked, and the rubber roll 30, which is an insulator that prevents corrosion of the internal carbon steel and prevents current from flowing, is lined with an insulating part on both sides of the steel band 20, and the inner wall of the cooling water ( W) works.

On the other hand, Figure 2 shows the structure of the steel band 20 and the rubber roll 30 of the conductor roll 1 in detail, the step (G) between the steel band 20 and the rubber roll (30) initially Since the step G is different from the thermal expansion rate between the steel band 20, which is a metal conducting portion, and the rubber roll 30, which is an insulating portion, the temperature rise due to the plating solution and the current during the plating operation of the actual steel sheet S is achieved. In consideration of this, the initial step is processed to have a constant step, and since the rubber roll 30 has a higher thermal expansion rate than that of the steel band 20, the initial step G is about 1-6 mm.

At this time, the band breeze (B) phenomenon easily generated in the conductor roll 1 during the electroplating of the steel sheet, as shown in Figure 3, the steel sheet (S) is in close contact with the steel band 20 of the conductor roll (1) When winding and conveying, the steel sheet is finely bent at the boundary between the steel band 20 and the rubber roll 30 due to the tension applied and the step G between the steel band 20 and the rubber roll 30. Since fine bending of the steel sheet does not disappear even after coating, it actually affects the product quality of the steel sheet.

On the contrary, as shown in FIG. 4, when the rubber roll 30 is over-expanded to become higher than the steel band 20 and a reverse step G ′ occurs, the steel sheet S is formed at the corner of the steel band 20. Since it is not in close contact with the steel band 20, an arc spot is generated in the gap portion, which causes fatal defects and damage to the roll 1 as well as the product of the steel sheet.

Therefore, it is necessary to improve surface defects such as band crises generated in conventional electroplating lines.

On the other hand, conventionally, since the rubber roll 30 of the conductor roll 1 is mainly made of a polyurethane material used in an electroplating line, the step G between the steel band 20 and the rubber roll 30 is a cooling water. (W) The temperature was approximately 0.6-0.7 mm when the temperature was 20 ° C.

However, in the conventional conductor roll 1 in which the polyurethane is made of the material of the rubber roll 30, blister occurs easily in the plating solution and due to the overexpansion of the rubber roll portion 30 described above. Arc spots are a problem. Currently, rubber rolls (30) made of a composite of ebony and variolastic based on Soll ac's patents (US4849083, 1989) are used for the conductor roll (1). At present, domestically developed multilastic similar to variola plastics is currently being used.

In addition, as shown in FIG. 2, the linear expansion number of the ebonite rubber roll 30b disposed adjacent to the steel band 20 in the material of the rubber roll 30 is 0.3 x 10 < -4 > The linear expansion coefficient of the outer multiplastic rubber roll 30a is 1.0 × 10-4 mm / ° C., whereas the linear expansion coefficient of conventional polyurethanes is 1.4 × 10-4 mm / ° C. Since the rubber roll 30 made of the materials 30a and 30b has such a low coefficient of linear expansion, the overexpansion of the rubber roll 30 during electroplating is alleviated, thereby improving the problem caused by the arc spot phenomenon. Or band marks), etc., are not improving.

The present invention has been made in order to solve the conventional problems as described above, its purpose is to adjust the temperature of the cooling water flowing in the conductor roll and the step between the skill band of the conductive roll and the rubber roll during the electroplating of the steel plate during the electroplating The present invention provides a conductor roll for electroplating of a steel sheet, which effectively prevents band cruising occurring at the edge portion of the band to improve plating quality of the steel sheet.

1 is a schematic perspective view showing a conductor roll for a general steel plate electroplating

Figure 2 is a detailed view showing the step structure between the steel band and the rubber roll in the conductor roll during electroplating

Figure 3 is a detailed view showing the band cris phenomenon according to the generation of the step between the steel band and the rubber roll in the conductor roll during electroplating

Figure 4 is a detailed view showing the over-expansion phenomenon of the rubber roll to generate an arc spot in the conductor roll during electroplating

Figure 5 is a graph showing the arc spot and band cracks generated state according to the step between the steel band and the rubber roll

FIG. 6 is a diagram illustrating a band width of a width according to a change in cooling water temperature of a conductor roll during electroplating.

(a) is a state diagram showing the case where the cooling water temperature is 35 ℃

(b) is a state diagram showing the case where the cooling water temperature is 40 ℃

(c) is a state diagram showing a case where the cooling water temperature is 45 ℃

FIG. 7 is a graph illustrating band crises and arc spots generated according to temperature changes of cooling water in a conductor roll during electroplating; FIG.

Explanation of symbols on the main parts of the drawings

1 .... Conductor roll 10 .... Roll inside wall

20 .... steel band 30 ... rubber roll

G .... step between steel band and rubber roll

W .... coolant

In order to achieve the above object, the present invention provides an inner wall through which cooling water flows, and a steel band and a rubber roll, each of which is disposed outwardly, wherein a step is formed between the steel band and the rubber roll. To

The step between the steel band and the rubber roll is formed from 0.25 to 0.35 mm, the temperature of the cooling water flowing through the inner wall of the conductor roll is 40 ~ 45 ℃, the rubber roll is made of the ebony material and the outer edge adjacent to the steel band By providing a conductor roll for steel plate electroplating to improve the plating quality consisting of a multi-plastic material.

DETAILED DESCRIPTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, and the same configuration as the conventional conductor roll is denoted by the same reference numerals, and the description thereof is briefly described.

As shown in Figures 1 and 2, the conductor roll 1 of the present invention is the portion of the rubber roll 30, the portion adjacent to the steel band 20 is an ebonite rubber roll having a linear expansion coefficient of 0.3 × 10-4 mm / ℃ ( 30b), and the outer roll is made of a multi-plastic rubber roll 30a having a coefficient of linear expansion of 1.0 × 10 -4 mm / ° C. In general, the conductor roll rubber roll 30 of the present invention is formed of ebonyite + multi-plastic ( Multilastic) has a rubber insulator, wherein the step (G) between the rubber roll 30 and the steel band 20 for sensing and energizing the plated material, that is, the steel sheet (S) is 0.25-0.35 mm, Preferably it is 0.30 mm.

2 and 3, when the step G between the steel band 20 and the rubber roll 30 is smaller than 0.25 mm, the bending phenomenon of the steel sheet S described in the related art is reduced and the band is reduced. If the amount of plating (B) decreases, on the contrary, if the plating amount increases or the line speed increases, the rubber roll 30 may overexpand when the solution temperature rises, so that the steel plate S and the steel band 20 Adhesion deteriorates and an arc spot easily arises.

On the contrary, when the step G is set higher than 0.35 mm, the coefficient of linear expansion of the ebonite rubber roll 30b adjacent to the steel band 20 is 0.3 × 10 -4 mm / Since it is not large as ° C., even if the rubber roll 30 expands, band crunch is generated without overcoming the initial step.

Therefore, in order to minimize the occurrence of arc spots and band cracks, which are a problem in the conventional conductor roll 1, the step G between the steel band 20 and the rubber roll 30 is 0.25-0.35 mm, preferably 0.30 mm.

On the other hand, Figure 5 shows the results of examining the number of arc spots generated and the band cris generation width for the range of the step, the coolant (W) for cooling the conductor roll (1) while flowing through the inner wall (10) The temperature of is about 25 ℃ room temperature.

That is, as can be seen in Figure 5, when the step (G) between the steel band 20 and the rubber roll 30 is less than 0.25, the generation width of the band crises is reduced, but on the contrary, the frequency of occurrence of the arc spot increases to lower the current When the abnormality such as lowering the speed is performed and the step G is larger than 0.35 mm, the number of occurrences of the arc spot is remarkably reduced while the occurrence of band crease increases rapidly. It can be seen that the case where the number of occurrences and the width of the art spot and the band crease are 0.25-0.35 mm, which is an average part, is most preferable. In this range, the band crease is somewhat generated, but it is still a stable operating environment.

Next, since the cooling water (W) circulated into the inside of the conductor roll (1) is directly supplied by the cooling tower, the temperature deviation occurs by more than 10 ℃ depending on the season and the operating time, and the cooling water temperature in the roll is In addition to the current density and the solution temperature (average 55 ℃) is an important factor that directly affects the thermal expansion of the conductor roll (1), and therefore in the present invention is not shown in detail in the drawings, but always constant rather than the conventional direct cooling method It would be desirable to take an indirect circulation cooling method that could maintain the temperature.

That is, the coolant temperature is heated to a desired temperature by injecting steam into the coolant circulation tank, and then circulated to each of the conductor rolls 1 of the plating line. Maintain a constant temperature at all times.

Next, in FIG. 6, the optimum cooling water temperature condition for reducing the band breeze (B) phenomenon when the step G between the steel band 20 and the rubber roll 30 is 0.3 mm was experimentally obtained through the examples. .

That is, Figure 6 shows the temperature of the cooling water (W) for the conductor roll (1) of the present invention for the low-medium carbon steel, which occupies the largest proportion of pure zinc plated steel sheet products when performing pure zinc (Pure-Zn) plating As the time progressed, the incidence (band width) of band crease was observed as time progressed.

At this time, the operating conditions were that the plating solution had a temperature of 55 ° C., a plating amount of about 20 g on the surface of the steel plate, and a transport speed of the steel plate was 105 mm / s, and the size of the material, that is, the steel plate was 0.6 t × 1219 mm.

Therefore, as can be seen in Figure 6a, when the temperature of the cooling water (W) is set to 30 ℃ bandwidth generation band appeared severely about 18mm at the beginning of the line operation and gradually weakened with the operating time 36 hours passed After about 11mm, the width is reduced, but it can be seen that the band crisping phenomenon is still visible to the naked eye.

In this case, the difference in the degree of occurrence according to the operating time is that the temperature of the conductor roll before the initial line operation is similar to the temperature of the coolant, and the conductive roll 1 is operated to come into contact with the plating solution (55-60 ° C) in the plating bath. This is because the temperature of the conductor roll 1 rises as a result of resistance heat caused by an energized current, and thermal expansion of the rubber roll 30 occurs. As time passes, a part of the plating solution is deposited on the rubber roll 30. This is because the contact area between the rubber roll 30 and the steel sheet S generally increases while penetrating and forming a space in the rubber roll.

Next, in FIG. 6B, when the temperature of the coolant is set to 40 ° C. and supplied to the conductor roll 1, the band-cries width decreases from 10 mm after 36 hours to about 5 mm after 36 hours. It can be seen that the band width is reduced and faded more than with cooling water.

Finally, in FIG. 6C, it can be seen that band crises are hardly generated from the beginning of the operation when the temperature of the coolant is set to 45 ° C. FIG.

However, when the temperature of the cooling water (W) in the conductor roll (1) of the present invention is greater than 45 ℃, there is a limit to increase the temperature by generating a fine spot, as shown in Figure 7, the steel band ( 20) and the step (G) between the rubber roll 30 is 0.3 mm, when the temperature of the coolant is 40 ~ 45 ℃, band crises and arc spots are minimized to enable the plating operation of the stable steel sheet Can be.

After all, the initial step (G) between the steel band 10 and the rubber roll 30 in the conductor roll 1 of the present invention is 0.25-0.35mm, most preferably 0.30mm, the temperature of the cooling water is 40 ~ 45 ℃ In this case, it can be seen that the improvement of plating quality is minimized by minimizing the generation of arc spots and band cracks generated in the conductor roll 1 and affecting the plating quality.

In addition, in the following Table 1, the degree of arc spot and band cris according to the temperature G of the steel band 10 and the rubber roll 30 and the temperature of the cooling water W in the conductor roll 1 of the present invention are tested. One result is shown.

Therefore, according to the above Table 1, when the rubber roll 30 is made of the ebonite 30b and the multi-plastic 30a, the step G between the steel band 20 and the rubber roll 30 is 0.25-0.35 mm. At the same time, when the temperature of the cooling water (W) is 40-45 ° C., the arc spot due to overexpansion of the rubber roll 30 and the vent crisp phenomenon due to low expansion of the rubber roll 30 are not reduced or generated. Able to know.

As described above, the present invention provides a method for preventing band cris defects resulting from the structural characteristics of a current carrying roll in manufacturing an electroplating product for use in automobiles and home appliances. By controlling the temperature of the cooling water appropriately, it is possible to prevent the band cruising and to produce the product without going through the additional process, thereby reducing the delivery time, reducing the cost, and ensuring the quality competitiveness.

While the invention has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention as set forth in the claims below. I would like to know that those who have knowledge of this can easily know.

Claims (1)

An inner wall 10 through which the coolant W flows, and a steel band 20 and a rubber roll 30 disposed at the outside thereof, respectively, and a step G is formed between the steel band 20 and the rubber roll 30. In the conductor roll 1 for electroplating a steel sheet, The step G between the steel band 20 and the rubber roll 30 is 0.25-0.35 mm, and the temperature of the cooling water W flowing through the inner wall 10 of the conductor roll 1 is 40-. 45 ° C., wherein the rubber roll 30 is formed of an ebonite material 30a adjacent to the steel band 20 and a multi-plastic material 30b outside thereof. role