JPS59185796A - Conductor roll for electroplating - Google Patents

Abstract

PURPOSE:To prevent generation of dents on the surface of a roll by providing fine ruggedness on the surface of a roll base consisting of a good conductor then forming a thin poor conductor layer over the entire surface and polishing the surface of the poor conductor layer thereby exposing the peak surface. CONSTITUTION:Fine ruggedness is formed on the outside circumferential surface of a roll base body 1 serving as the source for the shape and strength of a conductor roll, and thereafter the surface is coated with a good conductor 13 to constitute the base for the roll. Fine ruggedness is provided at about 0.1-7mu Ra surface roughness on the surface of such roll base by rough polishing and thereafter a poor conductor layer 15 is formed over the entire roughly polished surface. The surface of the layer 15 is then polished to expose the peak surface 17 in the projecting part of the conductor 13 while the layer 15 is left in the recess of the conductor 13. The life of the conductor roll is thus extended and the quality of the plated product is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductor roll used for electroplating.

A conductor roll is installed in an electroplating line to contact the material to be plated and keep the potential of the raw material at zero. Conventionally, the surface of the roll was made of a metal with good conductivity. During operation, part or all of the roll surface is immersed in the plating solution.

Next, a conductor roll for 2-in electroplating, in which a copper strip is plated with tin, will be explained as an example.

Conventionally, the roll base of conductor rolls and contactor rolls for electroplating is plated with chromium to improve the Ra of the roll surface. It is used after being polished to a roughness of about 3.5 μm. However, the surface of the roll is corroded by the highly corrosive halogen plating solution in the break section of the electric plating line, and the surface is abraded by contact with the surface of the copper strip.
As shown in the figure, the roughness gradually decreases. When the roll surface is corroded and its roughness deteriorates in this way, it becomes easy for tin to be electrodeposited on the roll surface and foreign matter to adhere to it, and as shown in Figure 2, more and more densities occur. .

Next, the mechanism of the generation of denso will be explained.

Commonly used chrome plated conductors
Taking a roll as an example, the chromium plating layer of the roll is eroded by the plating solution and becomes thin due to contact with the copper strip after a while after the start of use, and as shown in FIG. Fine cracks or pinholes S are formed in the chrome plating layer 3, which is a good conductor, on the outer periphery of the chrome plating layer 3, and the plating solution penetrates into the part 3, and the tin 7 is electrodeposited on the roll base plate whose potential is zero. The copper 7 gradually grows in the cracks or pinholes s, and eventually rises on the surface of the chrome plating layer 30 and becomes visible, forming protrusions called dents.

As shown in Fig. 2, these dents occur frequently as the roll usage time progresses, and they cause surface flaws in the tin plating and worsen the product yield, so the chrome plated conductor roll is The disadvantage is that it has a lifespan of only about 3-4 weeks.

An object of the present invention is to provide a conductor roll that solves the shortcoming of the conductor roll having a short life span, and the present invention provides a conductor roll as described in the claims of the present invention. By doing so, the object of the present invention can be achieved.

Next, the present invention will be explained in detail.

The present inventors believed that the following two points should be kept in mind in order to reduce the densities generated in the conductor roll in the plater section of the electric tinning line.

(a) The roll surface is configured so that tin is difficult to electrodeposit, and even if tin is electrodeposited, the electrodeposited copper is easily peeled off.

(b) Reduce the active area or current-carrying area of the roll surface.

In other words, when looking at the roll surface locally, the electrically active surface, which is the part of the roll surface where metal is exposed, is not in constant contact with the material to be plated; It is only for a short period of time, and even if it appears that they are in contact, they may not be in electrical contact.l)
, tin is likely to be electrodeposited on this part. Therefore, as this active area becomes larger, the probability that denso will occur there increases. However, from a macroscopic point of view, a certain amount of current-carrying area is necessary for the function of the conductor roll. Therefore, it is desirable to have a shape in which a large number of small energized portions are uniformly distributed on the roll surface. On the other hand, since the roll rotation is 200R, P, M, it will apparently contact the steel strip to be plated more than 10,000 times in 20 days, so it has sufficient durability to maintain the correct roll surface condition. sexuality is required.

To achieve the above requirements, conductors such as:
The inventors thought that it would be sufficient to make it into a roll. In other words, after forming fine irregularities on the outer periphery of the roll base, which is the source of conductor roll shape 9 strength, further fine irregularities are added to the roll base coated with a wear-resistant coating such as a good conductor. , forming a bad conductor layer, and then polishing the surface of the bad conductor layer to expose the top surface of the convex part of the good conductor, leaving the bad conductor layer in the concave part of the good conductor; It is made into a solid conductor roll.

The roll material may be the roll material of the roll base itself, which is made of a good electrical conductor.

In this conductor roll, the poor conductor surface covering almost the entire surface of the completed roll satisfies the requirements in item (a) above and resists wear, and the top surface of the convex portion of the good conductor becomes an effective active surface. We have now completed the present invention, which satisfies the requirements of item (b) above and constitutes an effective conductor roll.

The invention will be explained with reference to the drawings.

The fourth figure is an enlarged sectional view of the portion where the copper strip// and the conductor roll of the present invention are in contact. conductor
After forming fine irregularities on the outer periphery of the roll base (2), which is the source of the roll shape, the roll base (2) is coated with a good conductor (3) to form a roll base.

After coarsely polishing the surface of the roll base to have fine irregularities with a roughness of about 7 to 7 μm, a defective conductor layer is formed on the entire coarsely polished base surface.

Next, the left surface of the poor electrical conductor layer/3 is polished to expose the top surface/7 of the convex portion of the good electrical conductor/3.

At this time, the defective conductor layer 15 remains in four parts of the good conductor/3. Therefore, the steel strip is supported by the polished surface of the defective conductor layer and the top surface of the convex portion.

Poor abrasion-resistant conductor layer on roll surface/! The r surface prevents tin from being electrodeposited, and even if tin is electrodeposited, the electrodeposited copper is easily peeled off. The peelability of the tin in this area is better than that of the tip surface of the adjacent electrically active protrusion, so it is easy to remove the tin electrodeposited on the original image 7 before it grows and becomes a denso. It may peel off. Furthermore, as is clear from the processing procedure described above, the active surface 17 has a large number of narrow surfaces /7 scattered on the roll surface on average and has a small area, so that the electrodeposited copper does not grow in a dense manner. The narrow active surface /7 should be worn out because it is in contact with the copper strip // and conducts electricity, but the poor conductor layer / left side that closes the surface /7 is in contact with the steel strip //. The wear resistance of the poor conductor layer /S protects the active surface /7 from wear. In addition, the large number of active narrow surface cracks uniformly scattered over the entire surface of the roll reduces the arc spots that conventionally occur locally while the steel strip passes through the plating bath. Also, electrolytic corrosion on the roll surface can be reduced.

Next, examples of the present invention will be shown.

Example: The roll base surface, which is the source of the conductor roll, has a wc of about 33%, which has excellent wear resistance and corrosion resistance.

An alloy consisting of approximately 0% Ni, //% Cr, and the balance Fe is melted and coated to a thickness of approximately 7 ms, and the roll surface is coated with a Ra2. &~3. Roughly polished to a roughness of Sμm,
Added fine irregularities. The following two methods were used to cover the entire uneven surface with a thin electrically poor conductor layer and to process it thereafter.

A roll: The roughly polished alloy coating on the roll surface is heated to form an oxide film with a thickness of several μm to several tens of μm on the entire surface, and then this is polished to coat the surface with a fine metal with a diameter of 2 to 3 μm or less. The roll was made with many exposed surfaces.

B-roll: Ceramics such as main component S chromium oxide are thinly coated on the roughly polished alloy coating on the roll surface in a molten state, the restored coated surface is polished, and the fine metal surface of the alloy is applied to the polished surface. The roll was exposed with many dots.

When the above A and B rolls were attached to a halogen electric tinning line and put into practical use, the conventional chrome plating rolls had to be replaced every 3 to 1 weeks as mentioned above, whereas A, The B-roll is still in a fully usable condition even after more than a month has passed since it was first used.

For both A and B rolls, the part of the surface that is not electrically active is metal oxide (alloy oxide for A roll, ceramic for B roll), so it is in a state close to metallic bond with the base alloy. It is thought that they are strongly connected. Therefore, although these oxides are extremely thin, with a thickness of 7 μm or less and a thickness of several μm, it can be assumed that they are sufficiently resistant to vibrations during roll operation and external forces caused by contact with the copper strip.

Although oxides of metals, including ceramics, are themselves poor conductors, it is thought that some of them are not completely oxidized and are close to remaining metals, so from a macroscopic perspective, If you look at it, it cannot be said that it is a completely bad conductor. However, the activity is lower than that of pure metals, and it has been experimentally confirmed that electrodeposited tin has good removability.

As described above, when the conductor roll for electroplating of the present invention is used in a tin plating line, it has a long service life and has fewer densities and arc spots on the plating surface.
The product quality is improved, and there are fewer line strips to replace the conductor roll, making it extremely effective for tin plating lines.

The roll of the present invention is not limited to use in tin plating lines, but can also be applied to conductor rolls for other metal plating lines.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the change in Ra roughness on the surface of a conventional conductor roll and the date and time after the roll started to be used, and Figure 2 is a diagram showing the relationship between the number of denso occurrences of a conventional conductor roll and the date and time after the roll started to be used. Figure 3 is an explanatory diagram of the relationship between corrosion of a conventional chrome-plated roll and Denso, and Figure 3 is an enlarged sectional view of the part where the conductor roll of the present invention is in contact with the copper strip. . l...roll base, 3...chrome plating layer,!・・・
・Cracks or pinholes, 7...Electrodeposited tin? ...Denso, l/...steel strip, /3...good conductor, 15...
- Defective conductor layer, 17... active surface on the top surface of the convex portion. Patent applicant Kawasaki Steel Co., Ltd. agent Patent attorney Mura 1) Politics

Claims (1)

[Claims] 1. A conductor roll for electroplating, in which fine irregularities are provided on the surface of a roll base made of a good conductor, and then a thin poor conductor layer is formed on the entire surface, Next, the surface of the bad conductor layer is polished to expose the top surface of the convex portion of the good conductor, and the bad conductor layer is left in the concave portion of the good conductor. Conductor roll for plating. 2. In the roll according to claim 1, the roll base is formed by forming fine irregularities on the surface of the roll base, and then
The roll is further characterized in that the roll material is coated with a wear-resistant coating that is a good conductor. 3. In the roll described in claim 1,
A roll characterized in that the roll material is the roll material of the roll base itself, which is a good electrical conductor. 4. In the roll according to claim 1 or 2, the good conductor of the roll base material is about 35% WC, about yo% Ni, which is thermally sprayed on the roll base surface.
% of Cr and the balance of Fe. 5. In the roll according to any one of claims 1 to 4, the fine irregularities imparted to the good conductor have a roughness Ra o of 7 to 7 μm, which is imparted by rough polishing. A role characterized by certain things. 6. In the roll according to any one of claims 1, 2, and 4, the thin defective conductor formed on the entire uneven surface is thermally sprayed on the surface of the roll base. An oxide film is formed on the surface of the alloy when the alloy is heated. 7.% Allowance In the roll according to any one of claims 1 to 3, the thin defective conductor formed on the entire uneven surface is formed by melting ceramics whose main component is chromium oxide. A roll characterized in that the uneven surface of the roll is thinly coated.