Measuring and testing – Surface and cutting edge testing
Patent
1985-07-25
1987-02-10
Myracle, Jerry W.
Measuring and testing
Surface and cutting edge testing
25230119, 2524081, 250302, G01N 2191
Patent
active
046415181
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a process for the non-destructive inspection of surface defects, in that initially a solution with one or more dyes essentially having no emission under UV-light is applied and excess solution is removed after the dye has penetrated the surface defects and then the surface is covered with a developer leaving behind an absorbent coating and which contains at least one fluorescent component, the surface defects being revealed under UV-light as blackened portions within the light-emitting ambient.
For the non-destructive inspection or detection of surface defects, particularly on metal surfaces, the so-called red/white process is frequently used and consists of applying a solution with a dye having a high contrast in daylight to the surface, so that solution and dye can penetrate the surface defects. The excess solution is then removed from the surface, so that no dye residues are left behind. A coating is then applied, which leaves behind a background contrasting with the dye. For example, it can be a solvent with dispersed talc. After drying the coating, and surface defects are revealed by the coloring of the absorbent talc with the dye left behind in the surface defects.
A supplement to this process has been proposed for showing very small surface defects, such as cracks and the like (U.S. Pat. No. 3,564,249). In this process, following the wiping off of the dye applied, a developer is applied, which once again leaves behind a contrasting, e.g. approximately white and absorbent coating. This developer additionally contains a fluorescent component, which emits under UV-light. The absorbent component of the coating, which can also consist of talc, once again removes the dye from the surface defects. A complementary color is formed at the corresponding points from the dye and the fluorescent component and appears as a blackened portion under UV-light. These blackened portions can be detected clearly and in a sharply defined manner even when the red/white process leaves behind no or only unclear colorings. It is also pointed out that it need not be exclusively a red dye and also dyes in the blue range can be considered.
The known developer should contain approximately 1.5% of the essential component Fluoral 7 GA (product of General Aniline and Film Corporation). It is also proposed to add 3.2% of an optical brightener, in addition to the fluorescent dye.
Fluoral 7 GA and similar fluorescent dyes give the coating a striking yellow coloring, which impairs contrast in daylight. The problem to be solved by the present invention is to permit a better contrast within the coating.
SUMMARY OF THE INVENTION
On the basis of the aforementioned process, this problem is solved in that the fluorescent component is solely constituted by one or more optical brighteners in a proportion between 0.02 and 2.0% by weight of the total weight of the developer.
Practical tests with the developer having a composition according to the invention and which contains as the fluorescent component solely an optical brightener which is invisible in daylight in a much larger proportion compared with the Prior Art, have shown that the coating provides a high-contrast background both for the red/white process and for the UV-process, so that surface defects in daylight are made readily apparent by the red coloring and in UV-light by the blackening. In addition, fluorescent dyes are relatively expensive, whereas optical brighteners are used on an industrial scale in washing and bleaching agents and are consequently inexpensive. Thus, the invention not only provides an agent with improved use characteristics and consequently a more precise inspection process, but in addition the developer can also be produced less expensively.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to a preferred embodiment, the optical brightener is added to the developer in a proportion of 0.05 to 0.5% by weight. This makes it clear how small the added optical brightener quantity can be without having
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patent: 3108187 (1963-10-01), Thornbury
patent: 3506827 (1970-04-01), Alburger
patent: 3557015 (1971-01-01), Alburger
patent: 3564249 (1971-02-01), Molina
patent: 3679598 (1972-07-01), Alburger
patent: 3928046 (1975-12-01), Alburger
patent: 4377492 (1983-03-01), Jones
Brent Chemicals International PLC
Myracle Jerry W.
Noland Tom
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