Coating processes – Direct application of electrical – magnetic – wave – or... – Magnetic field or force utilized
Patent
1992-01-30
1994-08-16
Chin, Peter
Coating processes
Direct application of electrical, magnetic, wave, or...
Magnetic field or force utilized
118639, 118DIG11, 118405, B05D 100
Patent
active
053385810
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method, housing and a plant for the continuous/intermittent coating of objects by the passage of the objects through a bath a liquid coating product. The present invention applies in particular to the specific case of the galvanizing of metal objects with metal base or metal alloy products, but also to plants allowing to apply a liquid coating product of any other kind, such as certain resins or paints on certain metallic or non metallic objects.
2. Discussion of Background Information
In the field of metallurgy, plants for the continuous hot galvanizing of metal objects with zinc, aluminium or their alloys, in particular, are well known. A continuous galvanizing method using aluminium is described for example in French Patent FR-1 457 615 filed in the name of "Colorado Fuel and Iron Corporation", while continuous galvanizing with zinc and its alloys is described in French Patent FR-2 323 772 filed, in the name of Delot. In these two documents, it is proposed to improve the quality of the zinc or aluminium base anti-corrosion coating carried out on an elongated metal object, such as a concrete wire, in observing a common elementary principle concerning the intermetallic layer which developes in contact with the object's surface and the coating product. This layer is necessarily thin so as to avoid the risk of reducing the resistance of the superficial protective coating, as it is well established that a thick intermetallic layer tends to crack and come apart from the surface of the object it is supposed to protect.
This obtaining 8 of a thin intermetallic layer requires a very short intimate contact between a metallic object, which should be perfectly pickled and cleared of all its oxides, and a galvanizing bath at a temperature close to or slightly higher than that of the object, the bath also being perfectly free from any contact with an oxidizing agent (atmospheric air, floating matte composing a germ of oxides).
To reach this result, the techniques proposed in the two above mentioned patents are identical in that all the operations necessary for continuous galvanizing, i.e., the pickling and the heating of the object to be heated, then the quick intimate contact between the object and the bath in the housing, and perhaps the immediate cooling of the covered object (to stop the thermal diffusion causing the intermetallic layer to grow)-takes place under the controlled atmosphere of a neutral or reducing gas, maintained under pressure and at a temperature at suitable values (usually, at atmospheric pressure and at a temperature close to that of the object and the bath of zinc or molten aluminium). Another fundamental point common to both techniques consists in that the inlet and outlet holes to the galvanizing housing are aligned for the passage of the object to be covered, which makes possible continuous galvanizing. This method is far more advantageous than the competing galvanizing methods called "immersion coating", often applied to sheet metal. In these "immersion coating" methods, it is necessary to carry out an intermediate fluxing between the pickling and galvanizing, with the aim of this fluxing operation being to momentarily protect the cleaned surface of the object to be coated when it is exposed to the air, before immersion in the galvanizing bath.
Apart from the points they have in common, both of the above mentioned continuous galvanizing methods differ in particular in the elements used for pickling the object to be coated and for its heating, and especially in the elements used to seal the inlet and outlet holes to the galvanizing housing in which the molten aluminium or zinc bath is found. In this respect, it should be noted that it is more beneficial to use the zingage method described in French Patent FR-2 323 772 for the following reasons:
the pickling of the metal object to be coated is carried out mechanically (cold shot blasting), not chemically (reduction by hydrogen at a high temperature), w
REFERENCES:
patent: 2834692 (1955-03-01), Tama
patent: 3626964 (1971-12-01), Van Fossen
patent: 3701357 (1972-10-01), Granstrom et al.
patent: 3939799 (1976-02-01), Kanbara et al.
patent: 3970112 (1976-07-01), Bernard
patent: 4082207 (1978-04-01), Garnier
patent: 4169426 (1979-10-01), Kornmann et al.
patent: 4171707 (1979-10-01), Branover
patent: 4324266 (1982-04-01), Garnier
patent: 4655237 (1987-04-01), Gloor et al.
patent: 4904497 (1990-02-01), Lewis
patent: 4947895 (1990-08-01), Lillicrap
English Abstract of Japanese Application No. 61-235549.
Chin Peter
Delot Process, S.A.
Lamb Brenda
LandOfFree
Process and apparatus for the continuous or intermittent coating does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process and apparatus for the continuous or intermittent coating, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process and apparatus for the continuous or intermittent coating will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-950634