JPS6324095A - Method and apparatus for electroplating - Google Patents

Abstract

PURPOSE:To uniformize the flow velocity of a plating liquid and to execute plate to uniform quality and performance by forming respectively independent plating liquid flow passages of a pair of upper and lower anodes and a strip traveling between the anodes and sealing the inside of the spacing between the two anodes. CONSTITUTION:A pair of the insoluble anodes 27 are disposed on the top and bottom surfaces in a plating bath 22 in a tray wall 21 and a steel sheet 23 to be plated is run between the anodes 27. Edge sealing parts 34 having forked parts 34a are disposed to both side ends of the steel sheet 23 and masks 37 mounted to both side parts of both electrodes are brought into elastic contact with the edge sealing parts 34 to form the plating flow passages 35, 36 respectively independently between the anodes 27. A plating liquid sealing member 32 having a saw tooth shape is mounted to the inlet part of the anodes 27. The plating liquid 22 is fed from respective nozzle headers 29 via nozzles 28 to the respective flow passages 35, 36 in the above-mentioned constitution. The flow passages 35, 36 are respectively independent from each other and the inside between the two electrodes 27 is sealed by the sealing members 32, 34, 37; therefore, the pressure in the spacing between the electrodes 27 is increased to generate a substantial cushion force and to maintain the specified flow rates of the upper and lower flow passages 35, 36.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in a method and apparatus for continuously electroplating steel sheets.

[Prior art and its problems]

In recent years, there has been a growing demand for steel sheets for automobiles that have excellent corrosion resistance and workability, and galvanized alloy steel sheets have been developed as steel sheets that can meet these demands. Since the quality and performance of this alloy galvanized steel sheet, such as iron-galvanized steel sheet, depends on the flow condition of the plating solution at the polarization interface, various flow methods are used.

FIG. 10 shows the main parts of a conventional electroplating apparatus for manufacturing alloy galvanized steel sheets. This device has a pair of zinc polarized plates 2, 2 arranged facing each other in the vertical direction of a horizontally running steel plate 1, and a plating solution supply mechanism 3 equipped with a nozzle opening in the shape of a slit in the width direction. This mechanism supplies milling g to the gap between the electrodes 2, 2.

Note that 4 in the figure is a dam roll for sealing the plating solution. In this apparatus, the nozzle of the plating solution supply mechanism 3 is spaced apart from the electrodes 2, 2, and the plating flow rate between the electrodes in the vicinity of this rounded nozzle changes greatly. As a result, the composition of the alloy plating layer was non-uniform and the quality performance was low.

Furthermore, in the electroplating process, production costs account for a large proportion of the manufacturing cost. As a method of reducing this power cost, it has been proposed to shorten the distance between the electrodes. In other words, since the distance between the electrodes is the dominant factor in electrical resistance,
This is an attempt to lower electricity costs by lowering the electrical resistance of the current path. For example, in the plating apparatus shown in FIG. 11, plating liquid supply nozzles 6° 7.8 are formed at the front and rear ends and the center of the polarizers 2 and 20 in the direction of movement of the steel plate 1, and these nozzles The steel plate is shaped like a slit in the width direction of the steel plate. Then, the plating solution is supplied from the nozzle 7 in the center at a flow rate Qc to reduce the catenary of the steel plate, and the plating solution is supplied from the nozzles 6.8 at both ends at a flow rate Qr and Qo to increase the internal pressure between the electrodes. It is also sealed so that the plating solution has a cushioning effect (an effect that prevents catenary formation of the steel plate due to the pressure of the plating solution).

However, with this method, the sealing effect of the plating solution is not sufficient, and it is not always possible to obtain an effective seal.
Moreover, the plating discharge amount QX, Q.

does not flow between the electrodes and only performs sealing, so extra power is required. Furthermore, since the plating solution is supplied from the center of all the electrodes, the plating solution flows forward in the forward direction of the steel plate in the forward direction, and flows in a countercurrent flow backward in the forward direction of the steel plate. The relative flow velocity between the steel plate and the plating solution differs greatly between the front and the rear.9 As a result, there is a drawback that the quality performance of the alloy plating tends to vary.

FIG. 12 shows a structure in which both sides between the electrodes are closed and the plating solution is allowed to flow inside. With this structure, when the plating solution is flowed between the electrodes, the relative velocity of the plating solution against the steel plate becomes uniform,
Alloy plating quality performance problems are solved. However, since the two channels above and below the steel plate are in communication between the electrodes, it is difficult to increase the pressure of only the plating solution flowing below the steel plate. As a result, a sufficient cushioning effect cannot be obtained. Furthermore, the sealing of the nozzle (not shown) for supplying the plating solution is not sufficient, and for this reason, it is not possible to obtain enough pressure to provide a cushioning effect between the electrodes.

For this reason, the distance between the electrodes cannot be made too small, resulting in poor power usage efficiency.

Listed above are the problems with the conventional method and apparatus: The flow rate of the plating solution within the fl+'4 electrode is non-uniform, making it impossible to stably obtain a predetermined alloy plating performance.

(2) Further, in the fluid seal type, there is a problem in that extra power is required in addition to the problem in (1) above to seal with fluid.

(3) Top and bottom 1B again! Since the flow paths between the poles are in communication, no pressure difference can be created between the plating solution on the top of the steel plate and the plating solution on the bottom of the steel plate, resulting in an insufficient cushioning effect. It is not possible to reduce the distance between the two.

For this reason, plating cannot be performed at high current density, making it impossible to reduce power costs.

[Technical problem to be solved by the invention] This invention supplies a plating solution at a uniform flow rate between electrodes to obtain an alloy-plated steel sheet with uniform quality and performance, and also to separate the plating solutions flowing above and below the steel sheet. , to provide an electroplating method and apparatus that provide a cushion effect by creating a pressure difference in each plating solution, thereby reducing the amount of catenary, thereby reducing the distance between the υ electrodes, and performing highly efficient electroplating. The purpose is to

[Means to solve technical problems]

The present invention comprises a pair of anodes arranged vertically opposite each other, an edge mask surrounding both ends of a strip flowing between these anodes, and a sealing mechanism that closes both sides between the two anodes.
The upper anode, the strip, the upper plating solution flow path surrounded by the edge mask and the seal mechanism, and the lower anode, the strip,
It is equipped with a lower plating solution flow path that is surrounded by an edge mask and a sealing mechanism and is independent from the above-mentioned upper plating solution flow path, and allows plating 'gL to flow independently through each plating solution flow path, and at the same time to flow between the electrodes. This is an electroplating method in which electricity is passed between the strips while running them.

Furthermore, the present invention is an fc electroplating apparatus in which a plating solution is supplied to each of the channels from nozzles formed in a set of plating solution supply mechanisms.

That is, the present invention makes the flow paths between the upper and lower electrodes independent of each other and allows the plating tj to flow through each flow path at a predetermined flow rate.The cushioning effect of the fluid is enhanced, thereby reducing the distance between the electrodes. Is it possible? + Make it huge. This principle will be explained based on FIG.

In FIG. 1, reference numeral 11 indicates a steel plate, 12 an electrode, 13 a seal portion made of a non-circular material, and 14 a dam roll. When the plating solution flows in the same amount (flow rate Q) into the electrode 12 from the right side in the figure, and the pressure at the outlet of the flow path is f P o, the average pressure P applied between the electrodes is expressed by the formula [1].

ρ...Plating liquid density λl, λ2...Resistance coefficient bL+h2...Inter-electrode distance Lll"2...Inter-electrode length If the inter-electrode distance h2 is slightly displaced by Δh2 on one side from the center position, then The pressure difference ΔF that occurs is expressed by the formula [2], n
Ru.

However, the flow rate Q was kept constant, and the displacement of hl with respect to the change in h2 was made equal to the ratio of h2 and hl. [2] The value in brackets on the right side of the equation always takes a positive value. If the steel plate moves and the distance h2 between the polarizations decreases by the amount of movement Δh2 (negative amount), then from equation (2), the pressure is higher by Δh2 (positive value) at the shorter distance. As a result, this differential pressure allows the steel plate to be returned to its normal position. This is the principle of the cushion effect.

In order to obtain this cushioning effect, it is necessary to make the upper and lower channels independent from each other so that the flow rate is constant. If the upper and lower channels are not independent from each other, for example, if the position of the steel plate changes, one of the upstream and downstream channels becomes narrower and the pressure increases, and the other channel becomes wider and the pressure decreases, the plating solution will not flow. This is because the plating solution can freely flow back and forth between the upper and lower channels, and as a result, the plating solution flows into the channel with lower pressure, the difference in pressure is alleviated, and a cushioning effect cannot be expected.

The cushioning effect of this fluid can dampen the vibration of the steel plate by υ, but this effect increases as the pressure loss (100-PO) between the channels increases (as is clear from Equation 21. To increase the loss, a. Supply the plating solution from one end of the steel plate toward the other end to increase the flow path length (L+r L2).

b. The resistance coefficient λ2 is increased by setting the direction of the supplied plating solution to be opposite to the traveling direction of the steel plate.

C. λl is increased by using a highly effective sealing method such as a labyrinth method for the sealing part.

Examples of methods include:

Although it is efficient to supply the plating solution in a direction opposite to the traveling direction of the steel plate, it may be supplied in the downstream direction due to restrictions on nozzle installation. The key points are to partition the upper and lower electrodes to form mutually independent flow paths, to supply the plating solution from one end of the electrode to the other end, and to improve the sealing between the electrodes. Any material that increases internal pressure and obtains cushioning force may be used.

〔Example〕

Embodiments in which the present invention is applied to a galvanizing method and apparatus will be described below. FIG. 2 shows a cross section of the electroplating apparatus according to the present invention along the direction of movement of the steel plate;
The figure is a cross-sectional view taken along line -m in FIG. 2. In this electroplating apparatus, a plating bath 22 gold is placed in a tray wall 21, and a steel plate 23 to be galvanized runs within this plating bath 22. This steel plate 23 has a conductor roll 24 for energization.
, a dam roll 25 for damming the plating solution, and a support roll 26 for supporting the steel plate. This support role 2
6 is located in the middle of the tray. In the plating bath 22, insoluble anodes 27, 27 are arranged on the upper and lower surfaces of the steel plate 23. In front of the steel plate 23 in the advancing direction, each anode 27.
A plating solution supply nozzle 28.2 is installed at each end of the plating solution 27.
8 are integrally mounted and these nozzles 28,28 communicate with a nozzle header 29.29. In addition, 30 in the figure
．． 31 is a plating liquid sealing member made of hard rubber that is in contact with the outside of the tray wall; 32 is a plating liquid sealing member disposed at the inlet of positive 7427;
The flow path resistance is increased to improve the cushioning effect. 33 is a diluted plating solution sealing member disposed at the outlet of the anode 27.27.

Between these anodes 27 and 27, as shown in FIG. A two-crotch portion 34a made of rubber is formed at the bottom. The edge seal plate 34 and the steel plate 23 divide the plating solution flow paths 35 and 36 between the electrodes into upper and lower parts.

Furthermore, the edge seal plate 34 has its tip 30 fIr from the edge of the steel plate! If there is a meandering or change in width of the traveling steel plate 23 at a distance of about n, this will be detected and the position of the edge seal plate 34 will be changed accordingly based on this detection signal (description of the detection mechanism will be omitted). It is supposed to be done. In addition, the forked portion 34hIi at the tip is arranged so as to surround the edge portion of the steel plate 23 (for example, the overlap with the steel plate is 7″).
+mIS' (the shortest distance to the steel plate is set at 3) to prevent over-coating of the edges. Moreover, it deforms elastically in response to the vertical flapping of the steel plate 23, and always shields the plating solution in the upper and lower channels 35 and 36 of ≠4.

Furthermore, rubber masks 37... are attached to both sides of both electrodes 27, 27, respectively, and these masks 37...
- The tip elastically contacts the edge seal plate 34 to close the space between the electrodes and seal the plating solution flowing there. Here, the material of the mask 37 is made of rubber, which flexibly responds to the adjustment of the distance between the X electrodes, which requires changing the distance between the electrodes during unsteady operations such as sheet passing work, and has a sealing effect. This is to improve.

In this electroplating apparatus, the steel plate 23 travels from left to right in the figure, and the plating solution is pumped by the action of a pump (not shown).
Each nozzle header 29, 29 to nozzle 2B,...?
,! l to respective channels 35, 36. Each flow path 35, 36 is independent, and both sides between the electrodes are sealed, and the seal member 32 increases the flow path resistance of the plating solution, so that the flow path between the electrodes is sealed. The internal pressure increases and sufficient shock occurs. The plating solution then flows through outlet 38 into the tray.

Example 1 Two types of plating, iron-zinc alloy plating and pure zinc plating, were performed under the following conditions using an electroplating apparatus having the following general specifications.

/ , 2' k aperture I Q tHHX 2
100wn Discharge angle 20' from horizontal Steel plate Width 1880++a Thickness
Min. 0.8 Earthquake Electrode Fuku 2200 Length 1000 Material (1f Pb-Ag (0.5-1.0%) 12
)Ti-Pt (!1y=10μm plating) Number of trays
8 Distance between electrodes 8~10 Steel plate regular running speed 36~180 mpm Inso discharge flow rate 1.8 m/min/Header discharge pressure 40
m bath composition (for electrode material (1))
Content (9-/l)Z
nSO4・7H20150 FeSO4・7H20350 Na2SO430 CH3COONa-aF (2010 C6H8075 Bath composition (in case of 'it electrode material (2))
Content (9-/l
) ZnSO47H20150 F11SO4'7H20350 Na2SO430 MgSO470 Bath plating solution pH = 2.0 Bath temperature 50°C Relative speed to steel plate 2.0 m/a Current density DK = 50, 60, 80 A/dm2 Also, for comparison, plating with the above experimental example The conventional plating method shown in FIG. 1 was carried out under the same conditions.

The compositions of the plating films of Examples and Comparative Examples thus obtained were examined using G, D, and S (glow discharge spectroscopy).

The results are shown in FIG. 4 (comparative example) and FIG. 5 (experimental example). The vertical axis in the same figure shows the Fe content in the fitted film, and the horizontal axis is the passage of time (corresponds to the thickness direction of the film)
shows. As shown in Figure 4, there is a variation of ±2 to 3% with respect to the average content in the comparative examples, but in the experimental example in Figure 5, F
It can be seen that the variation in e content in the film thickness direction is much smaller than in the conventional method.

Experimental Example 2 Pure zinc plating was performed using the same cell dimensions as Experimental Example 1 and changing other conditions.

II! Pole material Pb-Ag (1%) Bath composition Component content (
P/1) ZnSO4・7H20400 Na2SO470 MgSO47Q pH=2.0. Bath temperature 50'C, flow density Dx = 1
2 OA/dm2 As mentioned above, no problems such as plating fading occurred during the six tests at high current density.

On the other hand, when electroplating was performed using the conventional method under the above conditions, plating discoloration occurred.

FIG. 6 shows the quiet pressure distribution between the electrodes obtained by the method of the present invention, and it can be seen from this distribution that sufficient pressure can be obtained due to the sealing effect.

Therefore, according to the present invention, due to the cushioning effect of the plating solution, the distance a between the electrodes, which was conventionally about 25 pieces, can be shortened to 8 pieces and 8 degrees, and the current density can be improved by more than 70% compared to the conventional method, resulting in high productivity. was able to achieve this.

Note that the sealing mechanism in the present invention is not limited to the above embodiment, and various methods can be considered. For example, as shown in FIG. 7, a rubber-lined bottom seal roll 41, 41f may be arranged between the edge seal plate 34 and the positive i2y, 2y.

Alternatively, as shown in FIG. 8, a seal rod 42 having a plurality of grooves on its outer periphery may be interposed between the anodes 27 and 27 to seal the anodes 27 and 27.

Experimental Example 3 A plating solution was caused to flow between the electrodes using the electroplating apparatus and conditions of Experimental Example 1, and the flow velocity distribution was measured. For comparison, plating spools were allowed to flow through the conventional device shown in FIG. 1 under the same conditions, and the flow velocity distribution was measured. The result is the 9th
As shown in the figure.

From the figure, the flow velocity distribution between the n electrodes obtained by the present invention is
It can be seen that it is much more uniform than the conventional one.

〔Effect of the invention〕

According to this invention, since the space between the electrodes is sealed by the sealing mechanism, the plating solution can flow therein at a uniform flow rate, and an alloy-plated steel sheet with uniform quality can be obtained.

In addition, since the plating solution flow paths on the top and bottom of the steel plate are independent, the cushioning effect due to the plating pressure is improved and the vibration of the steel plate is improved (Figure 9). can be performed with high efficiency.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention, FIG. 2 is a sectional view showing an embodiment of the electroplating method of the present invention, and FIG.
Figure 4 is a diagram showing the change in iron content over time (corresponding to the thickness direction of the film) in the conventional method; Figure 5 is a diagram showing the change in iron content over time in the example of the present invention. Figure 6 is a diagram showing the relationship between electrode direction distance and pressure in an example of the present invention, Figures 7 and 8 are diagrams showing changes in iron content due to changes in (corresponding to the thickness direction of the film). Diagrams showing different embodiments of the present invention; FIG. 9 is a diagram showing the relationship between electrode direction distance and flow velocity in an embodiment of the present invention together with a comparative example; FIGS. 10 to 12 show a conventional electroplating apparatus. It is an explanatory diagram. 2...Tray wall, 22...Plating bath, 23...
Steel plate, 27... Insoluble anode, 28... Nozzle, 29
... Nozzle header, 34 ... Edge seal plate, 3
41L...2 crotches, 35. , "j6... Plating solution flow path, 37... Mask. Chang 3 Mouth a4 Figure 5 81 C minutes) Time (minutes) Figure 6 Denkyose direction 1'1! Kyoshin [(m ) Fig. 7 Fig. 8 Fig. 9Il'21 Electric power shift AX long distance (m) g Fig. 10 Fig. 11 r Fig. 12

Claims (2)

[Claims] (1) A pair of anodes arranged vertically opposite to each other, an edge mask surrounding both ends of a strip flowing between these anodes, a sealing mechanism that closes both sides between the two anodes, an upper anode, a strip, The plating solution has an upper plating solution flow path surrounded by an edge mask and a seal mechanism, and a lower plating solution flow path surrounded by a lower anode, a strip, an edge mask, and a seal mechanism and is independent of the upper plating solution flow path. , an electroplating method in which a plating solution is made to flow independently through each plating solution flow path, and at the same time, a strip is made to run between the anodes and electricity is applied between the two. (2) a pair of anodes arranged vertically opposite to each other, an edge mask surrounding both ends of a strip flowing between these anodes, a sealing mechanism that closes both sides between the two anodes, an upper anode, a strip, an upper plating solution flow path surrounded by an edge mask and a seal mechanism; a lower plating solution flow path surrounded by a lower anode, a strip, an edge mask, and a seal mechanism and independent from the upper plating solution flow path; and a plating solution. An electroplating apparatus comprising: a set of plating solution supply mechanisms that supply plating solution from a supply nozzle to each of the channels.