Apparatus for a continuous selective electrodeposition on a stri

Details Apparatus for a continuous selective electrodeposition on a stri Apparatus for a continuous selective electrodeposition on a stri

1992-12-17

1995-02-14

Valentine, Donald R.

Chemistry: electrical and wave energy

Apparatus

Electrolytic

204224R, C25D 1700

Patent

active

053892208

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention is based on an apparatus for a continuous selective electrodeposition on a strip, comprising a carrier for guiding the strip in its longitudinal direction and electrolyte outlet orifices, which face said carrier and through which the electrolyte, which has been discharged by a pump, in sprayed onto the strip, which is covered by a mask tape, which is provided with at least one row of holes and urges the strip against the carrier, wherein drive means are provided for moving the strip relative to the mask tape.


PRIOR ART

Such apparatus are known from U.S. Pat. No. 4,431,500. In that known apparatus the strip to be selectively coated is guided on a wheel and by means of an immovable mask tape is firmly urged against that wheel. That mask tape is provided with one or more rows of holes and liquidtightly seals the strip to be coated, with the exception of the holes. Electrolyte supply orifices are arranged in a row along an arc of a circle around the wheel and the strip lying thereon and the mask tape and the electrolyte is sprayed under pressure through said orifices onto the mask tape and the accessible areas of the underlying strip. The formation of a depleted layer, which would otherwise form on the surface of the strip and would prevent the electrodeposition, is prevented by the relative movement between the strip and the mask tape.
Because the strip is guided on a wheel in that apparatus, the strip cannot selectively be coated on both sides in one operation. Apparatuses comprising straight carriers for guiding a strip to be selectively coated by electrodeposition are known from DE-32 12 152-C2 and WO-87/02076. DE-32 12 152-C2 also fails to permit a continuous selective electrodeposition on both sides of a strip because the mask tapes are urged against the strip to be coated in that the ferromagnetic mask tapes are magnetically attracted by magnets provided in the carrier. For this reason the rear side of the strip to be coated is not accessible because that rear side lies on the carrier.
The synchronous movement between the strip to be coated and the mask tape results on the surface to be coated and the mask tape results on the surface of the strip in the formation of a depleted zone, which opposes the deposition. For this reason that apparatus is of a different kind.
The apparatus according to WO-87/02076 also comprises a straight carrier. The electrolyte is supplied through a porous tape, which moves relative to the strip to be coated and is in contact with that strip and by its width and its position relative to the strip defines the area which is to be coated. But that can be accomplished only with previously punched tapes because the material which is abraded from the strip is retained in the pores of the porous tape and clogs said pores and is electrodeposited there and reduces the effective surface area of the porous tape. Only if punched strips are used will the following electrolyte be able to flush the abraded particles out of the porous tape at the punched openings of the strip. That necessary flushing of the porous strip with electrolyte through the punched holes of the strip to be coated cannot be accomplished if a strip which has not been prepunched but is continuous is employed and also could be accomplished only with difficulty if the strip is to be coated on both sides at the same time.


SUMMARY OF THE INVENTION

It is an object of the invention to provide an apparatus which is of the kind described first hereinbefore and by which any desired strip can be selectively coated by electrodeposition on one side and on both sides in one operation without a formation of a depleted zone, which would oppose the deposition, in the electrolyte on the surface of the strip.
In accordance with the present invention the object is accomplished by an apparatus having the features recited in claim 1. Desirable further features of the invention are subject matters of the dependent claims.
According to this invention the first step for a coating on both sides is performed

REFERENCES:
patent: 3723383 (1973-03-01), Johnson et al.
patent: 4431500 (1984-02-01), Messing et al.
patent: 4582583 (1986-04-01), Laverty et al.
patent: 4921583 (1990-05-01), Sewell et al.

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