JP2006249447A - Edge overcoat prevention device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an edge overcoat prevention device provided with a shielding board for uniformizing plating coating weight when a metal band is subjected to electroplating. <P>SOLUTION: The shielding board made of an electrically insulating material disposed between the edge parts on both the sides of a metal band as the material to be plated and an anode in a plating cell of an electroplating line, is formed in such a shape that the edge has a shape having protrusion showing a chevron shape having at least two tops drawn by a plurality of straight lines. The chevron shape at the edge is demarcated by a plurality of straight lines, wherein the angle α formed with a projected straight line drawn at a position confronted with the side edge in the metal band is 1 to 10°. Preferably, the two tops have a height of a prescribed distance Ea toward the center of the metal band based on the projected straight line, and also, the height Eb of the root part formed between the two tops is controlled to 50 to 80% of Ea. Further, the prescribed distance Ea is preferably controlled to 5 to 200 mm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to electroplating of metals such as tin, zinc, chromium, nickel and the like, and in particular, when electroplating one side of a metal strip that is a material to be plated, an edge that prevents overcoating at the end of the metal strip The present invention relates to an overcoat prevention device. The metal strip includes a steel strip, an aluminum strip and the like.

  In general, in electroplating a metal strip, the metal strip and the electrode are opposed to each other in a plating cell filled with an electrolytic solution, and a current is applied between the electrode and the metal strip to form a plating film on the surface of the metal strip. Form. However, since current tends to concentrate at both ends in the width direction of the metal strip as compared with the central portion, a phenomenon in which the plating thickness locally increases in the vicinity of the end portion, so-called edge overcoat phenomenon is likely to occur.

  As a method for preventing this edge overcoat phenomenon, it is known that a method of inserting a shielding plate between a material to be plated and an electrode is effective. For example, Patent Literature 1 proposes an apparatus for preventing excessive plating at the end of a steel strip in a continuous electric plating line that performs electrical plating on one side of the steel strip. In the apparatus described in Patent Document 1, as shown in FIG. 5, the L-shaped electrically insulating shielding plate 10 is horizontally aligned with the steel strip side end so as to protrude from the steel strip 4 side end to the steel strip center side. In order to prevent edge overcoat by forming a direction overlap Δx, the electrical insulation shielding plate is installed on the arm 9 together with the electrical insulation guide 8 that is in direct contact with the steel strip end to be plated. is doing. Thereby, it is said that the positional relationship with the steel strip can be kept well constant even with respect to the meandering of the steel strip.

However, in the apparatus described in Patent Document 1, if the overlap amount with the steel strip side end portion is too large, the plating thickness is too thin, resulting in an undercoat (underplating), while if the overlap amount is too small, The coating (excessive plating) tends to occur, and this apparatus has a problem that it is difficult to adjust the plating thickness at the end portion on the steel strip side.
In addition, in Patent Document 2, when electrogalvanizing is performed on one surface of a steel strip, a shield plate installed in a plating cell to prevent overcoating of the steel strip end portion is serrated at one end. The example of the plate-shaped blade-shaped shielding board provided with a blade-shaped part is described. However, in the shielding plate described in Patent Document 2, due to the complicated shape of the end face, turbulent flow occurs in the plating solution when the steel strip is passed through at high speed, so the steel strip vibrates and the distance between the poles is increased. There was a problem that the amount of plating adhered fluctuated and the upper surface of the steel strip was sometimes plated. Further, when tin plating is performed using this apparatus, there is a problem that sludge is trapped in the edge shape of the end face, so that it is necessary to care for it frequently, and also causes fluctuations in the liquid level. In addition, the trapped sludge bites between the roll and the steel strip, resulting in a surface defect of the plated steel strip.

  Further, in Patent Document 3, when forming a plating layer on both surfaces of a metal strip, it is installed between an electrode in the plating cell and the metal strip to prevent overcoating at the end of the metal strip. As an edge mask (shielding plate), as shown in FIG. 6, an edge mask (shielding plate) 11 provided with a flange 11a protruding beyond the side edge 41 of the metal strip 4 toward the center line side of the metal strip is proposed. Has been. In this edge mask (shielding plate) 11, the flange 11a has a non-perforated portion 11b and a large number of small holes continuously serrated along the longitudinal direction of the metal strip by a continuous straight line 11d drawn zigzag. It is partitioned into a portion 11c. However, the shielding plate described in Patent Document 3 is effective in preventing the plating solution from flowing when the metal strip is passed through, but sludge tends to accumulate in the small holes, causing undercoat. In addition, there is a problem that it is necessary to perform maintenance frequently.

Moreover, in patent document 4, when forming a plating layer on both surfaces of a steel strip, in order to prevent the overcoat of a steel strip edge part, as an edge mask installed between a steel strip and an electrode, An edge mask is disclosed that includes grooves into which both side edges are fitted, and an inner groove side edge of the groove having a sinusoidal waveform. However, the edge mask described in Patent Document 4 has a large change in the end face shape of the edge mask, and a turbulent flow is generated in the plating solution when passing through the steel strip. There was a problem that there was.
Japanese Patent Publication No.61-40320 Japanese Utility Model Publication 57-92764 Japanese Utility Model Publication No. 60-113374 Japanese Patent Laid-Open No. 10-110292

  The present invention solves the above-described problems of the prior art, prevents an edge overcoat that tends to be formed on the side of the metal strip when electroplating one side of the metal strip that is the material to be plated, An object of the present invention is to propose an edge overcoat prevention device provided with a shielding plate capable of uniforming the plating thickness of the plate.

  In order to achieve the above-mentioned problems, the present inventors pay attention to the turbulent flow generated in the plating solution during the passage of the metal strip that is the material to be plated, and the shape of the shielding plate that can suppress the generation of the turbulent flow We studied earnestly. As a result, the shield plate is provided with an overhang that overlaps the metal strip, the overlap area is adjusted to an appropriate range, and the shape of the shield plate that overlaps the metal strip (end face shape) It was found that it is important to prevent the generation of turbulent flow and remove sludge by using a mold shape and a shape with a small number of overhangs.

The present invention has been completed based on the above findings and further studies. That is, the gist of the present invention is as follows.
(1) In the plating cell of the electroplating line, it has a shielding plate made of an electrically insulating material disposed between both ends of the metal strip that is the material to be plated and the anode, and the edge over the end of the metal strip An edge overcoat prevention device for preventing coating, wherein the shielding plate has an edge near the center of the metal strip on the side parallel to the longitudinal direction of the metal strip and the shielding plate. An edge having a mountain shape having at least two peaks drawn by a plurality of straight lines having an angle α of 1 to 10 ° with a projected straight line drawn at a position facing the side edge of the metal strip in the same plane. An edge overcoat prevention device, characterized by being a shielding plate as an edge.
(2) In (1), the two peaks have a height of a predetermined distance Ea near the center of the metal strip with respect to the projected straight line, and are formed between the two peaks. The edge overcoat prevention device is characterized in that the height Eb is 50 to 80% of the predetermined distance Ea.
(3) The edge overcoat prevention device according to (2), wherein the predetermined distance Ea is 5 to 200 mm.

  According to the present invention, the edge overcoat is prevented, the plating thickness is made uniform, the edge cutting margin can be reduced, and the yield of the plated metal strip is improved. Moreover, according to this invention, the plating thickness which has adhered excessively to the edge part can be made thin, and there also exists an effect that the usage-amount of a plating metal can be reduced.

The edge overcoat preventing device of the present invention can be applied to an electroplating line of metal such as tin, zinc, chromium, nickel and the like. The applied electroplating line may be either horizontal or vertical.
The edge overcoat prevention apparatus of this invention has a plate-shaped shielding board. Needless to say, the edge overcoat prevention device is provided with an auxiliary device such as a known shielding plate supporting means in addition to the shielding plate. The shielding plate is supported by shielding plate support means (not shown). The shielding plate support means preferably includes means for moving the metal strip in the width direction so as to be able to cope with plating of metal strips having different plate widths.

  The shielding plate 1 in the present invention is made of a plate-like electrical insulating material and is formed into an L shape. One end of the shielding plate 1 disposed in the horizontal direction is immersed in the plating solution 6 of the plating cell 61, and a predetermined distance between the side end portion of the metal strip 4 which is the material to be plated and the anode 5 is obtained. It arrange | positions so that it may become a position. In the present invention, the shielding plate 1 is preferably arranged so as to overlap with the metal strip 4 by a predetermined amount. This state is shown in FIG. In FIG. 2, the direction perpendicular to the paper surface is the sheet passing direction of the metal strip 4, and shows a cross section on one side of the plating cell.

  Further, the shielding plate 1 according to the present invention has a projected straight line 41 (also referred to as a side edge corresponding position) drawn at a position where one end disposed in the horizontal direction faces the side end of the metal strip 4 within the same plane. It has an edge with a shape projecting closer to the center of the metal strip. That is, as shown in FIG. 1, the shielding plate 1 according to the present invention has a chevron shape with the edge near the center of the metal strip 4 projecting on the side parallel to the longitudinal direction of the metal strip 4. FIG. 1 is a plan view schematically showing an example of the planar shape of the shielding plate. By defining the edge to have a chevron shape, the shielding area between the metal strip and the electrode can be reduced and the edge undercoat amount can be reduced as compared with the case of a flat edge shape. .

  Further, the mountain shape of the edge in the present invention has at least two apexes P1 and P2. By making at least two peaks in the shape of a chevron, the amount of plating current that wraps around from the slope of the chevron is increased, and the portion that becomes the undercoat is reduced compared to the case where there is only one peak. It is easy to achieve uniform plating thickness. In the shape of a mountain with a single apex, the shielding area between the metal strip and the electrode can be reduced compared to a flat edge shape. However, since the shielding area is too large, sufficient current does not flow at the end. In many cases, the plating current to the end portion becomes insufficient and a portion to be an undercoat is generated.

In the present invention, it is preferable that there are two or more peaks in the mountain shape of the edge.
In the present invention, the chevron shape of the edge is in the range of 1 to 10 degrees with respect to each angle αi formed with the projection straight line 41 drawn at a position facing the side edge of the metal strip in the same plane as the shielding plate. A plurality of straight lines 1 to i, for example, four straight lines 1 to 4 as shown in FIG. As the angle αi, an angle within the above-described range can be arbitrarily selected according to the length L of the shielding plate determined in accordance with the size of the plating cell and the amount of projection of the shielding plate. If the angle αi formed with the projection straight line 41 is less than 1 °, the projecting area of the shielding plate becomes too small, and it becomes difficult to adjust the shielding area (overlap amount) between the metal strip and the electrode to an appropriate value. On the other hand, if αi exceeds 10 °, the projecting area of the shielding plate becomes too large, the plating current to the end becomes insufficient, and an undercoat portion occurs.

  Further, in the shielding plate according to the present invention, as shown in FIG. 1, two apexes, or one of the two apexes, is based on a projected straight line 41 drawn at a position facing the side edge of the metal strip described above. It is preferable that the height Eb of the valley bottom portion formed between these two peaks is 50 to 80% of Ea. If Eb is less than 50% of Ea, the shielding area is reduced and overcoating occurs. On the other hand, if Eb exceeds 80% of Ea, the shielding area increases and the plating thickness becomes non-uniform. In the present invention, the heights from the projection lines 41 at the two apexes are not necessarily the same.

In the present invention, Ea is preferably in the range of 5 to 200 mm. If Ea is less than 5 mm, the end becomes an overcoat. On the other hand, if it exceeds 200 mm, the shielding area becomes too large, and an undercoat at the end often occurs.
By providing an edge overcoat prevention device with a shielding plate as described above in the electroplating line, the amount of plating current to the end of the metal strip is optimized, and of course, the overcoat on the end of the metal strip In addition, it is possible to suppress the generation of turbulent flow of the plating solution during the passage of the metal strip, and it is possible to stably manufacture the plated metal strip having a uniform plating adhesion amount.

Using a continuous electric tin plating line, one side of a cold-rolled steel strip (plate thickness: 0.22 mm × width: 881 mm) was tin-plated. In performing electrotin plating, an edge overcoat prevention device was disposed in the plating cell. The edge overcoat prevention device was provided with three kinds of shielding plates, and each was subjected to electrotin plating. The used shielding plates are (1) shielding plate shown in FIG. 1 (example of the present invention), (2) shielding plate shown in FIG. 3 (a) (conventional example), and (3) shielding plate shown in FIG. 3 (b). (Comparative example). About the obtained tin plating steel strip, the tin plating adhesion amount distribution was measured by the electrolytic method. The plating bath was a halogen bath, the plate passing speed was 350 mm / min, and the amount of plating was 1.32 g / m ² . In the shielding plate shown in FIG. 1, Ea: 15 mm, Eb: 10 mm, α1: 3.3 °, α2: 3.3 °, α3: 3.3 °, α4: 3.3 °. In the shielding plate shown in FIG. 3B, Ea: 20 mm, α1: 3.3 °, and α2: 3.3 °.

  The obtained tin plating adhesion amount distribution is shown in FIG. From FIG. 4, when electrotin plating was performed using the edge overcoat prevention device provided with the shielding plate of FIG. 1 of the example of the present invention, no end overcoat or undercoat was observed, and uniform It is an electrotin-plated steel strip with a distribution of plating adhesion. On the other hand, when the electrotin plating is performed using the edge overcoat preventing device provided with the shielding plate of FIG. 3B of the comparative example, an undercoat is recognized at the end. Moreover, when electrotin plating is performed using the edge overcoat prevention device provided with the shielding plate of FIG. 3A of the conventional example, the end portion is a remarkable overcoat. When electrotin plating was performed using the edge overcoat prevention device of the present invention example, the margin for cutting off the edges could be reduced, and the yield was improved by 1.44% compared to the conventional example.

It is a top view which shows typically an example of the shielding board in this invention. It is sectional drawing which shows an example of the arrangement | positioning condition of the shielding board in this invention. It is a top view which shows typically the shielding board which is (a) a prior art example and (b) a comparative example. It is a graph which shows the influence of the shape of a shielding board on the shape of a shielding board, and tin plating adhesion amount distribution. It is a schematic diagram which shows an example of the conventional shielding board. It is a schematic diagram which shows an example of the conventional shielding board.

Explanation of symbols

1 Shield plate 4 Metal strip (steel strip)
5 Anode 6 Plating solution 8 Electrical insulating guide 9 Arm
10 L-shaped electrical insulating shield
11 Edge mask (shielding plate)
11a flange
11b Non-porous part
11c Small hole part
41 Projected line
61 Plating tank (plating cell)

Claims (3)

  In the plating cell of the electroplating line, there is a shielding plate made of an electrically insulating material that is placed between both ends of the metal strip that is the material to be plated and the anode, preventing edge overcoat at the end of the metal strip An edge overcoat preventing device, wherein the shielding plate has an edge near the center of the metal strip on the side parallel to the longitudinal direction of the metal strip in the same plane as the shielding plate. And an edge having a mountain shape having at least two peaks drawn by a plurality of straight lines having an angle α of 1 to 10 ° with a projected straight line drawn at a position facing the side edge of the metal strip. An edge overcoat prevention device, which is a shielding plate.   The two apexes have a height of a predetermined distance Ea near the center of the metal strip with respect to the projected straight line, and the height Eb of the valley bottom formed between the two apexes is the predetermined height Eb. 2. The edge overcoat prevention device according to claim 1, wherein the edge overcoat prevention device is 50 to 80% of the distance Ea.   3. The edge overcoat prevention device according to claim 2, wherein the predetermined distance Ea is 5 to 200 mm.

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