LU82230A1 - SURFACE QUALITY CONTROL PROCESS - Google Patents

Description

t 2.UÔ3; C 201S / 3003.

ιί j • j ’i" il Ί,: i j *, Ί? j he METALLURGICAL RESEARCH CENTER -CENTRUM VOOR RESEARCH IN DE METALLURGIE,

Non-profit association - vereniging sonder v: in s toogrr.erk: in BRUXELLES, (Belgium).

ί î; j) Quality control process for these surfaces, j ^ - - _ —— _ ~~ J 4

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The present invention relates to a method ce j; quality control of these surfaces, whether they are either nor.

ï i coated with one or all of them, layers c ‘a cuel- f belt coating! ~ - · ... conch, and whatever their iron serves. The process is also applied when the objects making the surfaces are to be measured, released in motion.

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title c eueiiipus non imitât ir, us prc ·. t · .... os _ 1 tr.vsr. t j or. t 'ît—' "': / olxcuant s any solce of on’ sce this cuelau' extent. · / if- 2.-

The quality c $ s metal sheets can be conceived in two directions, on the one hand, that yes concerns the material itself of the sheet, which must have well defined properties from the mechanical point of view, structure, homogeneity and isotropy and on the other hand, that, concerned by the present invention, relating to the appearance of its surface coated or not, with a coating or paint.

This surface quality is directly linked to its more or less smooth or shiny appearance, as well as to its ho-. homogeneity and its consistency in the said aspect.

With regard to coated surfaces and in particular painted metal surfaces that have been produced in large quantities in automobile bodywork, the different surfaces of an assembly must not only be the brightest; bones, but also have the same gloss so that their quality is considered satisfactory. It is therefore necessary this power to judge this the shine that a painted surface, regardless of the color used, to control such productions.

In this field, methods have already been used based on the power of resolution of the painted surface used as a mirror. However, the results thus obtained depend on the appreciation of the operator with all the well-known disadvantages of this practice.

With regard to the uncoated surfaces and 'in particular those these metal sheets therefore the surface is preserved on a microscopic scale in the forma a succession of peaks and valleys, knows that their morphology which had known' 'importance, is characterized by different parameters such as average arithmetic roughness, number 6th peaks per unit ce Ion- ff n _ - ^ * ï î _. "I p / y ν-" "4

In this field / the same applicant has already presented a method making it possible to remedy the above-mentioned drawbacks / method characterized in that a light beam of the laser type of low power is directed towards the on-face, an incidence of preferably oblique, in so far as it determines, under appropriate conditions, the opening angle of the cone! reflected light and in that we deduce the quality of the j said surface in the sense that a larger opening angle corresponds to a greater irregularity of the surface.

s The object of the present invention is to reveal a v other method by which it is possible, in a particularly facilitated manner, to implement the process already mentioned, imagined by the applicant, especially in cases where we are dealing with surfaces curved or mobile pa.jL uT cDuur t 3UX G îSODSit IIS 06 FT; 6: S \ XX * 3 i i. i.

used.

The above-mentioned method being based on the measurement of the intensity of a beam reflected by the sheet whose brightness is to be measured, there appear certain practical difficulties when it is desired to measure the intensity reflected in an angle â'or-! weak vertex in the center of the beam, or cetermi "-r, by means of a screen, the opening angle of the reflected beam. The latter case requires either a large and therefore expensive screen, or a precise auxiliary device for bring the reflected beam closer to 1 ': measurement screen.

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The process, object of the present invention, according to which ► a laser beam is projected onto the surface whose properties one wants to measure, this reflectivity and of brightness, is tested. 't so characterized in that the bitter or.u ray, t reflected by the said surface, in the form of a more or less flared beam, is received for the most part, and preferably as a whole, by a detector photosensitive, passing through one or more of these notches zen by. as c ‘a shutter su mov eme.nt, comprising these alternations this opaque zones and this leds notches / Guarantors and in this we put on the retort s has te alternatits eu

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4.- siynal produced by the photosensitive detector, the said signal being representative of the desired brightness of the sheet.

According to the method of the invention, the movement of the shutter is such that the reflected beam successively encounters at least one transparent zone and one opaque zone, and preferably successively several alternations, this opaque and transparent zones.

Depending on the characteristics of the shutter and the quality of the surface to be measured, several cases may arise: a. the shutter consists of a series of alternately transparent and opaque zones, the width of which is substantially equal to the diameter which, at the angle of said shutter, presents a beam reflected by a sheet whose surface is considered to be very shiny and very regular, in this hypothesis, the area of the sensitive surface of the receiver hit by the beam can receive, over time, an illumination represented by the diagram of FIG. 1, the passage of an opaque area of the shutter is translating by an almost zero intensity of the illumination, · the alternative component of the signal is represented by Ay on rigare 1.

If, with this type of shutter, we are dealing with a surface of which the qualities of brightness and / or regularity are clearly less good, the diameter of the reflected beam will be appreciably larger at the location of the shutter and the receiver will record, as a function of time, a ciagr antre of the kind that that of signal A of flower 2.

The comparison of the diagrams allows this to conclude if one tele is brighter than another, or if it has these characteristics of acceptable brilliance, eu eosrc to a standard / * ~ f G ΟΠΠ0 · /, 5.- b. The shutter is made up of a series of alternately transparent and opaque zones, the width of the transparent zones of which is much smaller than the diameter of a spot reflected by a surface considered to be bright and smooth.

In this hypothesis, the area that the surface sensitive to the receiver struck by the beam of small diameter (corresponding to a smooth sheet), can receive over time an i ^ illumination representable by the diagram of Figure 3, the pass- i ”Saae from one zone to the next zone resulting in the recording of a signal very analogous to a pulse (C ^) - 'If on the other hand, with such a shutter, the diameter of the reflected beam is appreciably larger than in the previous case, and even sometimes greater than the width of the opaque strip of 11cb-, turator, the area of the sensitive or receiving surface struck by the reflected beam during the displacement of the shutter itself; translated by the recording of a signal such as that shown * in Figure 4 (whose alternative value C „is identified in the drawing).

The oroeédé making the ebiet this the straight lutentier. ; has the advantage of considerably facilitating the measurement of the illumination due to the reflected beam, which can be done easily; 4 ment in an angular opening of 10th, then had according to known methods, measurements had to be made in the center of the reflected beam, for example according to an opening of the order of (1/50) °.

According to the invention, there are different means that 'design a shutter filling the cc-niitior.s required pou the implementation of the above process, * however, the preferred j; is given to a shutter in the form of this slotted disc (with receiver inside the cylinder - Figures 7 and 8). / '6. -

According to an advantageous modalite of the method of the invention, the total reflected intensity of the sheet is further measured at the point considered, which makes it possible to determine its brightness (ratio or difference between the quantities measured according to the above-mentioned method and the 'total reflected intensity). Two methods can then be used with interest: - either the measurement of the continuous component these signals received through the shutters, - or by deflecting part of the reflected beam, towards a second photometric cell, by means of a semi-plate - show through. . -j, located upstream of the shutter (relative to the path of the reflected radiation).

According to another advantageous modality of the method described in the present invention, when we are dealing with surfaces whose relative position can vary within wide limits, we can reduce the variations in direction and position of the reflected beam by passing the laser radiation successively on two flat mirrors before reaching the surface whose reflectivity is to be measured, the first of these mirrors being fixed with respect to the laser, the round being parallel to the SUIIc: C6 G0 £ ct ςΟΊ6 6Π ίτ "-ΓΪ pO 1 * 1C ÛS mSSUXS,.

The obligatory parallelism between the rays striking the second mirror and those reflected by the surface surface results, in the event of displacement of the surface surface, by a simple displacement of the reflected beam, which remains very substantially parallel to itself, during of its movement, this ass facilitates the measurement to be made.

In the case where we are dealing with a particularly smooth and shiny surface, the very small divergence of the laser beam can be artificially increased, by massaging m · îz. ~ ^ v tT s .c> "c ^ * n * · - *" f- et ~ "tc r“ ”^ -c. - t -” - ~ ~ -n rt rl— * ”-” “- < *; »» - * i-ï w, v * i '«-a. W» ... »_ · _ ÇC« · v * ^ ___ ... „______ ^ Cà _ ~ w -L - w * laser) or. to relation: output divergence = input divergence xc: -re ---- -

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Claims (8)

1. Method for controlling the quality of surfaces, i according to which a laser beam is projected onto the surface of which the properties of reflectivity and this brightness are to be measured, characterized in that the radiation reriecni by is orite surface, in the form of a more or less flared beam is received for the most part, and preferably for all of it, by a sensitive sensor, passing through one or more of these transparent zones, a shutter in motion, comprising alternations of opaque zones and transparent zones, and in this aue the alternating component of the signal supplied by the photosensitive detector is measured. 2. Method according to claim 1, characterized in that the movement of the shutter is: such had the reflected beam successively meets at least one transparent area and an opaque area, and this preferably successively several alternations this opaque and transparent areas. : <! 3. Method according to claims 1 to 2, characterized in that the shutter consists of a series of zones, alternately transparent and opac_ss and of which the. width is substantially equal to the diameter presented, e i enaroiu du un. - shutter, a beam reflected by a torus whose surface is considered to be very shiny and r ·· -gu. ·. .: e. & GuiVant X £ S Γ 6 b Γ: G î C a è i D Γ. £ · * · ~ characterized in that the shutter is made up of a series of alternately transparent and opaque areas, and cor.t the width of a reflected beam because of a surface considered cc-same brt.yt / Xante and smooth . / * / - / 8.- 5. Method according to either of these claims 1 to 4 / characterized in that the shutter has the form of slotted disc. 6. Method according to either of claims 1 to 4, characterized in that the shutter has the shape of a cylinder provided with slots. 7. Method according to either of claims 1 to 6, characterized in that in addition, the total reflected intensity * of the sheet is measured at the location considered. 8. Method according to claim 7, characterized in that one divides one by the other or subtracts one from the au-Lie oocenue measures o a share, according to claims 1 to 6, and on the other hand according to claim 7 B. Method according to t A 0 claims / or S, terized in this eue said measurement oe ISk. ..,. , _ „P-iLensite total reilecms is obtained by measuring the comos-_ * ^ nte continuous these signals received through the shutters. 1Ö * irJCOC0G6 S'JlVâTïC ^ irevenoications 7 or 3 / Cs "taken into account the measurement of the in *... ^. __ '^ reflected total tension e-- obtained by deviating from it a part of the do · “*" V ^ = u reflected towards a s® "conde r-hotometricue cell, in Nov. ~ -,. _“ C 'a semi-transparent blade “located upstream of the shutter (by ^ contribution to the path of reflected radiation). "J .. i ^ rOCSG ^ 1? m - Or id \ j.— C0S cations 1 to 10, characterized in this eue" * when dealing with ess surfaces whose relative oosifcion, r, ~. . compared to 1 * instructing · - - IffwSUr’S oe’ûC vcri ^ r Ccr.Γ: S CS C-Ccr.-dsî r · --jT & νθΓιΠ0Γ ^ 0Πΰ £. 3 2Γ SC.CCSSS1 V -SÛT.-ΒΓ.Ci SUS -t v ^>; ir.ircirs plar.s, a * - ar- ~ to reach the surface to be trusted **. ~ 'ivity is to be measured, l & X / r s /, ·. * t / ο ~ · first of these mirrors being fixed relative to the laser, the second being parallel to the surface of the sheet at its point this measurement. 12. Method according to one or the other of claims i v cations 1 to 11, characterized in that, when one is dealing with one! particularly smooth or shiny surface, the laser beam is passed through a telescope, before it touches the sensitive surface of the receiver, and this preference also before it reaches the surface to be measured. , t! i ii! »'Ί 11 d -, ___. λ π - π £ "19 .ο ... * 'tr" "-, v ι, y ----- - - o 00ΓΗ .. · * .............. F ~ - .....? É ..... "\. . - r.vtno-caio'c ... Λ- '"/..;. -. _descriptif; ..>.> * ·:": -' 1 - ··· · i i * i \ j