Coating processes – Nonuniform coating – Mask or stencil utilized
Patent
1998-03-06
1999-04-06
Bareford, Katherine A.
Coating processes
Nonuniform coating
Mask or stencil utilized
427284, 427287, 427429, 118264, 118266, 118505, B05G 128, B05G 132, B05C 106, B05C 116
Patent
active
058915214
DESCRIPTION:
BRIEF SUMMARY
This is a national stage application of PCT/JP96/02550, filed Sep. 6, 1996.
TECHNICAL FIELD
The present invention relates to an improvement in a method and apparatus for painting (or corrosion-proofing) the cut edge (or end edge) of a precoated steel sheet cut to the final dimensions of the finished product or a processed article thereof (hereinafter sometimes referred to simply as a "precoated steel sheet" or "precoated steel") used for the production of a product of a construction using a precoated steel sheet for its exterior plate such as electrical products, furnitures, building materials, and auto parts.
BACKGROUND ART
Consumer goods such as electrical products, furnitures, building materials, auto parts, are being reassessed as to the steel sheet used in their external structures from the viewpoint of recycling, elimination of harmful substances in waste disposal, and the ecology. Further, even among the steel sheets used, ferrous metal manufacturers are painting the outer surface of the steel sheet with the paint of the final product and using this as starting material. Therefore, the precoated steel sheet is being viewed with interest as being capable of eliminating the painting step at the manufacturer of the final product.
The problem with using such a precoated steel sheet as an outer plate is that, when cutting the precoated steel sheet to the final dimensions of the finished product, the cut edge becomes a bare ferrous metal having no paint or plating. Therefore, for products which are to be used in environments requiring rust-proofing (even products used in normal indoor environments often require rust-proofing at portions exposed at the outside in view of the image of the product) and products where the strange feeling given by the color of the paint of the precoated steel sheet and the metallic luster of the cut edge would detract from the image of the product, one either has to give up on the use of a precoated steel sheet (use an ordinary steel sheet and paint it after processing) or else paint the cut edge after the processing.
Note that in the case of such post-painting of the cut edge, it is necessary to prevent the paint from spreading to the decorative surface of the precoated steel sheet so as to protect the beauty of the decorative surface. However, the thickness of the steel sheet used here is about 1 mm or an extremely thin steel sheet of even less than 1 mm. Painting such a thickness of a cut edge without spreading over to the decorative surface is extremely difficult even using various manual painting methods such as spray painting or roller painting--it is close to impossible to perform by automatic painting machines.
In the past, the technique known as "masking" is used to deal with this problem. For example, as shown in FIG. 1, the portion on the precoated steel sheet 1, on which spreading of paint was desired to be prevented, was covered in advance by masking tape 2 along the surface to be painted, the painting was conducted in that state, then the tape was peeled off after painting. Thus the beautiful painting free from spreading to the surface to be protected can be obtained. By masking in this way, various methods of painting were possible. However, when attaching the masking tape, it is necessary to attach the tape exactly along the complicated contour of the processed surface of the product. This could only be done by careful manual work by workers and was therefore a costly, time-consuming technique.
As a prior art relating to coating of a chemical on to the end edge of a plate material, while differing in the field of art, Japanese Unexamined Patent Publication (Kokai) No. 5-263271 has proposed a technique of coating a photoresist on to the end edge of a lead frame plate.
However, in the protective painting of the cut edge of a precoated steel sheet to which the present invention is concerned, it is most preferred from the perspectives of the cost of the painting and the beauty of the exterior appearance that only the cut edge and its surroundings be painted,
REFERENCES:
patent: 3947614 (1976-03-01), Becker
Kuriyama Yukihisa
Marumoto Seiichi
Nishioka Ryoji
Ueda Kohei
Bareford Katherine A.
Nippon Steel Corporation
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