EP0767509A1 - Wear indicator, in particular for thermoplastic radome and method of fabrication - Google Patents

Wear indicator, in particular for thermoplastic radome and method of fabrication Download PDF

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Publication number
EP0767509A1
EP0767509A1 EP96402117A EP96402117A EP0767509A1 EP 0767509 A1 EP0767509 A1 EP 0767509A1 EP 96402117 A EP96402117 A EP 96402117A EP 96402117 A EP96402117 A EP 96402117A EP 0767509 A1 EP0767509 A1 EP 0767509A1
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EP
European Patent Office
Prior art keywords
radome
wear indicator
patch
indicator according
wear
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Granted
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EP96402117A
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German (de)
French (fr)
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EP0767509B1 (en
Inventor
Charles Thomson-CSF SCPI Garnot
Serge Thomson-CSF SCPI Laforet
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome

Definitions

  • the present invention relates to a wear indicator, in particular for radome, and more specifically for injected thermosplastic radome. It also relates to a method of manufacturing a radome provided with this erosion indicator.
  • a radome is a protective dome of an antenna. It is made of a material compatible with the reception by the antenna of electromagnetic waves, the most commonly used material originally being glass-epoxy, which is a thermosetting material.
  • thermosetting material a thermoplastic material, more precisely that known under the name of PEEK ("Poly-Ether-Ether-Ketone”), formed under high temperature and high pressure.
  • PEEK Poly-Ether-Ether-Ketone
  • thermoplastic materials Despite their very good performance, these thermoplastic materials nevertheless undergo erosion due to the impact of raindrops, on which it is necessary for the user, or "aircraft manufacturer”, to have information constantly or periodically.
  • a first solution very simple but in fact very impractical, consists in providing, locally on the radome, an excess of material constituting a wear indicator. It is then necessary that this surplus of material is provided in an area where it does not disturb the reception or emission of radio waves, which limits its possibilities of use.
  • the wear of this excess material is practically not detectable for an observer who is generally placed on the ground.
  • Another solution is to use a measuring device specially designed to measure this wear of the radome. It is typically a tubular bearing device which is placed coaxially on the top of the radome, on which it fits. A measuring instrument, acting by comparison, then measures the distance between a fixed point of the measuring device and the tip of the radome, this distance increasing as the wear of the radome increases.
  • the outer layer is made of material resistant to rain erosion, and it is of a different color from that of the underlying layers, thus constituting an indicator of erosion of the radome.
  • This known method effectively makes it possible to obtain a reliable erosion indicator, but it is only applicable if the radome has a layered structure. Since the outer layer is the most resistant, as soon as the exposed part of the outer layer disappears by erosion, this disappearance is indeed visible by color change, but then it may be too late, because the total thickness of the radome is generally weak ( ⁇ 2 mm), and the underlying layers may not be strong enough and rupture during use of the radome. Indeed, a visual inspection can make believe that the part is good whereas it only a tiny thickness of the outer layer remains, and erosion can accelerate quickly after disappearance of this remaining outer layer.
  • the present invention relates to an erosion or wear indicator, which is easy to produce both for molded objects and for laminated objects and which gives an indication of wear or erosion well before embrittlement. objects.
  • the wear indicator of the invention for a part to be monitored is characterized in that it is constituted by at least one patch, of a color different from that of the material of which the part is made, which is integrated into the structure. of the part, and which is positioned, in this part so that its part which has become visible following wear of the part gives an indication of the degree of wear.
  • this pellet has a conical shape arranged so that its axis is perpendicular to the outer surface subject to wear, the tip of the cone being directed towards this surface.
  • this control patch is placed in the nose of the radome and coaxially with it.
  • this pellet is made of the same thermoplastic material as the radome, which has the advantage of not modifying the rate of erosion before and after indication of wear.
  • the invention is described below with reference to a radome, but it is understood that it is not limited to such an application, and that it can be implemented in any application where one needs a visual indication of the degree of wear or erosion of a part, in particular when one cannot directly notice this degree of wear (edge of the part not visible, part difficult to access or inconspicuous or requiring disassembly to be able to be measured).
  • the wear in question is that of a radome for protecting airborne equipment, due essentially to rain erosion, but it is understood that the invention can also be implementation for parts subjected to different other kinds of wear (by friction in particular).
  • FIGS. 1 and 2 a distinction is made in FIG. 1 for the injection mold which will be used to manufacture the radome 14 of FIG. 2.
  • This mold consists on the one hand of a male part 1 composed of a base 2 surmounted by a nipple 3 of the same profile as that of the internal surface 4 of the radome 14 of FIG. 2, and the top of which is provided with a stud 5 whose role will be explained below, and on the other hand a conjugated female part 6 which defines an internal surface 8 of same profile as the external surface of the radome 14 of FIG. 2.
  • this female part 6 is conventionally provided with an axial injection “core” 9 which is a channel by which the components of the thermoplastic material are injected into the mold in the molten state, under high pressure and high temperature. .
  • thermoplastic material in question in this preferred embodiment is PEEK (Poly-Ether-Ether-Ketone).
  • the stud 5 and the cavity 11 are replaced by a temporary bonding of the patch to the male part 1.
  • the tablet 10 could be obtained by an injection process in a small mold provided for this purpose, instead of being produced by machining.
  • the components of the PEEK constituting the radome of FIG. 2 are injected by the injection core 9.
  • the external part of the tablet 10 is then brought to a temperature sufficient to melt locally, so that this tablet comes to be welded to the body 12 of the radome, composed of PEEK of another color, and therefore to drown in a way in this body 12 of the radome 14.
  • the radome 14 of FIG. 2 is finally obtained, entirely made of PEEK and comprising, on the tip of its internal surface 4 and set back with respect to the tip 13 of its external surface 8, a patch 10 of a different color from that which constitutes the remaining part of radome 14.
  • the patch 10 can be provided on its cylindrical surface with means holding it in place, for example ribs of revolution or equivalent devices (radial asperities, thread, ...) which prevent it from being ejected if it is poorly welded to the body 12, when its front face is released as a result of erosion.
  • FIGS 3 to 5 illustrate the role of rain erosion indicator which is played by this patch 10.
  • the radome 14, mounted on its receiving base 15, is seen from the front.
  • the radome When the rain erosion is not sufficient for the tip of the external surface 8 of the radome 14 to be worn down to the patch 14, the radome is presented as in FIG. 3, its point then being of the same color as the remaining part of the radome.
  • the pellet When, following rain erosion, the thickness of the radome at its tip has decreased sufficiently, the pellet begins to appear as drawn in Figure 4, that is to say in a granulated appearance, with dots of color of the patch, and dots of the color of the radome. This is due to the fact that erosion due to raindrops is not carried out uniformly, but in a particulate way, each impact of raindrops removing a small particle of material.
  • pellets can be placed, grouped in the same zone or distributed under the entire external surface to be monitored. These pellets are then colored with different colors, and are of different lengths, which makes it possible to determine different degrees of wear. Of course, their dye must not harm the dielectric qualities of the radome.
  • FIG. 6 shows another embodiment of the patch of the invention.
  • the radome 17 has at its front part a pellet 18 of conical shape.
  • the axis of this cone is perpendicular to the outer surface of the radome and is, in this case, confused with the axis of the radome, but it may not be confused in cases where it is not the apex of the radome which is the place subject to maximum erosion.
  • the tip of the cone may be flush with the outer surface of the radome or be slightly recessed.
  • the color of the material constituting the pellet is different from that constituting the radome. Thanks to such a pellet, the degree of wear of the radome is known at all times, which is proportional to the visible surface of the pellet.
  • the radome 19 may include several pellets, cylindrical or conical, arranged in the places most subject to erosion. This figure shows three such pellets, referenced 20, 21 and 22.
  • pellets of the invention can also be used for a radome with a laminated structure.
  • the invention can also be implemented for parts other than radomes and subjected to wear, when their thickness cannot be determined directly.
  • the invention is not limited to the preferred example which has just been described. This is how it is advantageous, in particular not to disturb the reception of electromagnetic waves, that the patch 10 is made of the same thermoplastic material as the body 12 of the radome, but this is not limiting and this patch could very well be provided in a thermoplastic material of another kind. It is also thus that this pellet could be kept in place in the mold by a suction process instead of being by mechanical means. It is thus also that this same patch could not be positioned in the nose of the radome 14, in a coaxial manner with the latter, but be more or less offset with respect to its axis, depending in fact on the place of impact. maximum raindrops. Of course, in most cases of use, the tablet is of sufficiently small dimensions not to adversely influence the uniformity of the qualities of the parts containing it.

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  • Details Of Aerials (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Abstract

The indicator includes a tab (10) which is formed from a thermoplastic material and has a thickness which is less than that of the radome or the part it is required to monitor. It is placed in position (5) in a male section of the radome moulding. The moulding is closed and a thermoplastic is injected into the mould so as to partially fuse the tab and integrate it totally with the body (12) of the radome. The tab is placed coaxially in the nose of the radome on the internal surface with a hollow (11) which is complementary to a retaining bulge on the male section of the mould.

Description

La présente invention se rapporte à un indicateur d'usure, en particulier pour radôme, et plus spécifiquement pour radôme thermosplastique injecté. Elle se rapporte également à un procédé de fabrication d'un radôme muni de cet indicateur d'érosion.The present invention relates to a wear indicator, in particular for radome, and more specifically for injected thermosplastic radome. It also relates to a method of manufacturing a radome provided with this erosion indicator.

Un radôme est un dôme de protection d'une antenne. Il est réalisé en un matériau compatible avec la réception, par l'antenne, des ondes électromagnétiques, le matériau le plus couramment utilisé à l'origine étant le verre-époxy, qui est un matériau thermodurcissable.A radome is a protective dome of an antenna. It is made of a material compatible with the reception by the antenna of electromagnetic waves, the most commonly used material originally being glass-epoxy, which is a thermosetting material.

En particulier lorsque ces radômes sont utilisés pour protéger les antennes placées sur les avions (radôme de pointe avant, radômes de haut de dérive, d'extrémité d'ailes,...), on a constaté que les impacts de gouttes de pluie provoquent, avec ces radômes en matériau thermodurcissable, une usure rapide et finalement un perçage et donc une destruction du radôme, ce phénomène étant d'autant plus dévastateur que les vitesses des avions sont élevées, ce qui est en particulier le cas pour les avions supersoniques modernes.In particular when these radomes are used to protect the antennas placed on aircraft (front tip radome, top drift radomes, wing tip radomes, etc.), it has been observed that the impacts of raindrops cause , with these radomes made of thermosetting material, rapid wear and finally piercing and therefore destruction of the radome, this phenomenon being all the more devastating as the speeds of the planes are high, which is in particular the case for modern supersonic planes .

Une première solution utilisée pour remédier à ce phénomène d'érosion pluviale aété l'utilisation de peintures spéciales, ce qui s'est révélé finalement insuffisant.A first solution used to remedy this phenomenon of rain erosion was the use of special paints, which ultimately proved to be insufficient.

Un grand progrès récent en la matière a alors consisté à remplacer le verre-époxy, matériau thermodurcissable, par un matériau thermoplastique, plus précisément celui connu sous le nom de PEEK ("Poly-Ether-Ether-Ketone"), mis en forme sous haute température et haute pression.A great recent progress in the matter then consisted in replacing the glass-epoxy, thermosetting material, by a thermoplastic material, more precisely that known under the name of PEEK ("Poly-Ether-Ether-Ketone"), formed under high temperature and high pressure.

Malgré leurs très bonnes performances, ces matériaux thermoplastiques subissent néanmoins une érosion due à l'impact des gouttes de pluie, sur laquelle il est nécessaire que l'utilisateur, ou "avionneur", ait constamment ou périodiquement des informations.Despite their very good performance, these thermoplastic materials nevertheless undergo erosion due to the impact of raindrops, on which it is necessary for the user, or "aircraft manufacturer", to have information constantly or periodically.

Il existe actuellement deux solutions pour obtenir des informations de contrôle de l'usure de ces radômes thermoplastiques modernes.There are currently two solutions for obtaining wear control information from these modern thermoplastic radomes.

Une première solution, très simple mais en fait fort peu pratique, consiste à prévoir, localement sur le radôme, un surplus de matière constituant un témoin d'usure. Il est alors nécessaire que ce surplus de matière soit prévu dans une zone où il ne perturbe pas la réception ou l'émission des ondes radioélectriques, ce qui en limite les possibilités d'utilisation. En outre, pour des radômes placés en hauteur et donc difficilement accessibles visuellement, par exemple en haut de dérive de l'avion, l'usure de ce surplus de matière n'est pratiquement pas décelable pour un observateur qui est généralement placé au sol.A first solution, very simple but in fact very impractical, consists in providing, locally on the radome, an excess of material constituting a wear indicator. It is then necessary that this surplus of material is provided in an area where it does not disturb the reception or emission of radio waves, which limits its possibilities of use. In addition, for radomes placed at a height and therefore difficult to visually access, for example at the top of the aircraft fin, the wear of this excess material is practically not detectable for an observer who is generally placed on the ground.

Une autre solution consiste à utiliser un appareil de mesure spécialement conçu pour mesurer cette usure du radôme. Il s'agit typiquement d'un appareil de portée tubulaire que l'on vient poser coaxialement sur le sommet du radôme, sur lequel il s'adapte. Un instrument de mesure, agissant par comparaison, mesure alors la distance entre un point fixe de l'appareil de mesure et la pointe du radôme, cette distance augmentant lorsque l'usure du radôme augmente.Another solution is to use a measuring device specially designed to measure this wear of the radome. It is typically a tubular bearing device which is placed coaxially on the top of the radome, on which it fits. A measuring instrument, acting by comparison, then measures the distance between a fixed point of the measuring device and the tip of the radome, this distance increasing as the wear of the radome increases.

Cette dernière solution, si elle est très satisfaisante sur le plan intellectuel, est cependant très lourde et onéreuse en exploitation. Il faut en effet concevoir un appareil de mesure adapté aux dimensions de chaque radôme, et prévoir le stockage et la maintenance de chacun de ces appareils de mesure. En outre, chaque mesure nécessite le démontage du radôme pour l'amener au sol et faire la mesure, puis le remontage de ce radôme sur l'avion une fois la mesure faite.This last solution, if it is very satisfactory on the intellectual level, is however very heavy and expensive in exploitation. It is indeed necessary to design a measuring device adapted to the dimensions of each radome, and provide for the storage and maintenance of each of these measuring devices. In addition, each measurement requires disassembly of the radome to bring it to the ground and make the measurement, then reassembly of this radome on the aircraft once the measurement has been made.

On connaît d'après la demande de brevet européen 0 158 116 un procédé de réalisation de radômes à l'aide de couches superposées de fibres tissées et de feuilles de matière plastique. Selon un mode de réalisation, la couche externe est en matériau résistant à l'érosion pluviale, et elle est d'une couleur différente de celle des couches sous-jacentes, constituant ainsi un indicateur d'érosion du radôme.We know from European patent application 0 158 116 a process for producing radomes using superimposed layers of woven fibers and plastic sheets. According to one embodiment, the outer layer is made of material resistant to rain erosion, and it is of a different color from that of the underlying layers, thus constituting an indicator of erosion of the radome.

Ce procédé connu permet effectivement d'obtenir un indicateur d'érosion fiable, mais il n'est applicable qu'au cas où le radôme a une structure stratifiée. Etant donné que la couche extérieure est la plus résistante, dès que la partie exposée de la couche extérieure disparaît par érosion, cette disparition est en effet visible par changement de couleur, mais alors il peut être trop tard, car l'épaisseur totale du radôme est généralement faible (< 2 mm), et les couches sous-jacentes peuvent ne pas être suffisamment résistantes et se rompre en cours d'utilisation du radôme. En effet, un contrôle visuel peut faire croire que la pièce est bonne alors qu'il ne reste qu'une épaisseur infime de la couche extérieure, et l'érosion peut s'accélérer rapidement après disparition de cette couche extérieure restante. De plus, ce procédé connu est pratiquement inapplicable lorsque les radômes sont fabriqués par injection, en particulier du fait qu'il est alors difficile de réaliser une "couche" externe colorée d'épaisseur constante et précise, et que si l'on réalisait malgré cela de tels radômes, ils seraient complexes à réaliser et trop onéreux, car il faudrait utiliser au moins deux moules différents. De plus, il est inutile de mesurer l'érosion là où elle ne peut se produire.This known method effectively makes it possible to obtain a reliable erosion indicator, but it is only applicable if the radome has a layered structure. Since the outer layer is the most resistant, as soon as the exposed part of the outer layer disappears by erosion, this disappearance is indeed visible by color change, but then it may be too late, because the total thickness of the radome is generally weak (<2 mm), and the underlying layers may not be strong enough and rupture during use of the radome. Indeed, a visual inspection can make believe that the part is good whereas it only a tiny thickness of the outer layer remains, and erosion can accelerate quickly after disappearance of this remaining outer layer. In addition, this known process is practically inapplicable when the radomes are produced by injection, in particular because it is then difficult to produce a colored external "layer" of constant and precise thickness, and only if it is produced in spite of that of such radomes, they would be complex to produce and too expensive, since it would be necessary to use at least two different molds. In addition, there is no point in measuring erosion where it cannot occur.

La présente invention a pour objet un indicateur d'érosion ou d'usure, qui soit facile à réaliser aussi bien pour des objets moulés que pour des objets stratifiés et qui donne une indication d'usure ou d'érosion bien avant la fragilisation de ces objets.The present invention relates to an erosion or wear indicator, which is easy to produce both for molded objects and for laminated objects and which gives an indication of wear or erosion well before embrittlement. objects.

L'indicateur d'usure de l'invention pour une pièce à surveiller est caractérisé en ce qu'il est constitué par au moins une pastille, de couleur différente de celle de la matière dont la pièce est constituée, qui est intégrée à la structure de la pièce, et qui est positionnée, dans cette pièce de sorte que sa partie devenue visible suite à l'usure de la pièce donne une indication du degré d'usure. De façon avantageuse, cette pastille a une forme conique disposée de telle façon que son axe soit perpendiculaire à la surface extérieure soumise à usure, la pointe du cône étant dirigée vers cette surface.The wear indicator of the invention for a part to be monitored is characterized in that it is constituted by at least one patch, of a color different from that of the material of which the part is made, which is integrated into the structure. of the part, and which is positioned, in this part so that its part which has become visible following wear of the part gives an indication of the degree of wear. Advantageously, this pellet has a conical shape arranged so that its axis is perpendicular to the outer surface subject to wear, the tip of the cone being directed towards this surface.

Préférentiellement, dans le cas d'un radôme, cette pastille-témoin est placée dans le nez du radôme et coaxialement avec celui-ci.Preferably, in the case of a radome, this control patch is placed in the nose of the radome and coaxially with it.

Préférentiellement aussi, cette pastille est réalisée dans la même matière thermoplastique que le radôme, ce qui présente l'avantage de ne pas modifier la vitesse d'érosion avant et après indication d'usure.Also preferably, this pellet is made of the same thermoplastic material as the radome, which has the advantage of not modifying the rate of erosion before and after indication of wear.

L'invention se rapporte aussi à un procédé de fabrication par injection d'un radôme thermoplastique muni de cet indicateur d'érosion, ce procédé consistant :

  • . à fabriquer tout d'abord au moins une pastille thermoplastique de couleur différente de celle du corps du radôme, mais moins épaisse que celui-ci,
  • . à rapporter cette pastille sur la partie mâle du moule d'injection du radôme, à l'endroit correspondant à sa position future dans le corps du radôme,
  • . puis, après avoir refermé le moule, à injecter dans celui-ci la matière thermoplastique, ladite pastille s'intégrant alors totalement, par fusion partielle, au corps de ce radôme.
The invention also relates to a method of manufacturing by injection of a thermoplastic radome provided with this erosion indicator, this method consisting of:
  • . first of all to manufacture at least one thermoplastic pellet of a color different from that of the body of the radome, but thinner than the latter,
  • . to attach this patch to the male part of the radome injection mold, at the place corresponding to its future position in the body of the radome,
  • . then, after having closed the mold, to inject therein the thermoplastic material, said pellet then integrating completely, by partial fusion, into the body of this radome.

L'invention sera mieux comprise, et ses avantages et diverses caractéristiques ressortiront mieux, lors de la description suivante d'un exemple non limitatif de réalisation, en référence au dessin schématique annexé dans lequel :

  • La figure 1 illustre, selon une coupe longitudinale du moule d'injection, la fabrication par injection d'un radôme thermoplastique muni de cet indicateur d'érosion,
  • La figure 2 est une coupe longitudinale du radôme ainsi obtenu
  • Les figures 3 à 5 schématisent, en vue de face du radôme de la figure 2, les phases d'usure successives de ce radôme, et
  • Les figures 6 et 7 sont des vues en coupe de variantes du dispositif de l'invention pour un radôme.
The invention will be better understood, and its advantages and various characteristics will become more apparent from the following description of a nonlimiting exemplary embodiment, with reference to the appended schematic drawing in which:
  • FIG. 1 illustrates, in a longitudinal section of the injection mold, the manufacture by injection of a thermoplastic radome provided with this erosion indicator,
  • Figure 2 is a longitudinal section of the radome thus obtained
  • FIGS. 3 to 5 show diagrammatically, in front view of the radome of FIG. 2, the successive wear phases of this radome, and
  • Figures 6 and 7 are sectional views of variants of the device of the invention for a radome.

L'invention est décrite ci-dessous en référence à un radôme, mais il est bien entendu qu'elle n'est pas limitée à une telle application, et qu'elle peut être mise en oeuvre dans toute application où l'on a besoin d'une indication visuelle du degré d'usure ou d'érosion d'une pièce, en particulier lorsque l'on ne peut pas se rendre compte directement de ce degré d'usure (tranche de la pièce non visible, pièce difficilement accessible ou peu visible ou nécessitant un démontage pour pouvoir être mesurée).The invention is described below with reference to a radome, but it is understood that it is not limited to such an application, and that it can be implemented in any application where one needs a visual indication of the degree of wear or erosion of a part, in particular when one cannot directly notice this degree of wear (edge of the part not visible, part difficult to access or inconspicuous or requiring disassembly to be able to be measured).

Dans le cas, décrit ci-dessous, l'usure dont il s'agit est celle d'un radôme de protection d'équipements aéroportés, due essentiellement à l'érosion pluviale, mais il est bien entendu que l'invention peut être également mise en oeuvre pour des pièces soumises à différentes autres sortes d'usure (par frottement en particulier).In the case described below, the wear in question is that of a radome for protecting airborne equipment, due essentially to rain erosion, but it is understood that the invention can also be implementation for parts subjected to different other kinds of wear (by friction in particular).

En se référant tout d'abord aux figures 1 et 2, on distingue sur la figure 1 le moule d'injection qui va servir à la fabrication du radôme 14 de la figure 2.Referring first to FIGS. 1 and 2, a distinction is made in FIG. 1 for the injection mold which will be used to manufacture the radome 14 of FIG. 2.

Ce moule se compose d'une part d'une partie mâle 1 composée d'une base 2 surmontée d'un mamelon 3 de même profil que celui de la surface interne 4 du radôme 14 de la figure 2, et dont le sommet est pourvu d'un téton 5 dont le rôle sera précisé ci-après, et d'autre part d'une partie femelle conjuguée 6 qui définit une surface interne 8 de même profil que la surface externe du radôme 14 de la figure 2.This mold consists on the one hand of a male part 1 composed of a base 2 surmounted by a nipple 3 of the same profile as that of the internal surface 4 of the radome 14 of FIG. 2, and the top of which is provided with a stud 5 whose role will be explained below, and on the other hand a conjugated female part 6 which defines an internal surface 8 of same profile as the external surface of the radome 14 of FIG. 2.

En outre, cette partie femelle 6 est classiquement pourvue d'une "carotte" d'injection axiale 9 qui est un canal par lequel les composants de la matière thermoplastique sont injectés dans le moule à l'état fondu, sous forte pression et haute température.In addition, this female part 6 is conventionally provided with an axial injection "core" 9 which is a channel by which the components of the thermoplastic material are injected into the mold in the molten state, under high pressure and high temperature. .

La matière thermoplastique dont il s'agit dans cet exemple préférentiel de réalisation est du PEEK (Poly-Ether-Ether-Ketone).The thermoplastic material in question in this preferred embodiment is PEEK (Poly-Ether-Ether-Ketone).

Avant de fermer le moule, une pastille préalablement usinée 10, en PEEK de couleur différente de celle de la matière dont le radôme va être constitué, est placée au sommet du mamelon 3 de la partie mâle 1 du moule, et maintenu à cet endroit par le fait qu'elle possède une petite cavité 11 (Figure 2) dont la forme est complémentaire de celle du téton précité 5, ce dernier venant donc s'encastrer étroitement dans cette cavité en maintenant ainsi en place la pastille usinée 10. En variante, on remplace le téton 5 et la cavité 11 par un collage provisoire de la pastille à la partie mâle 1.Before closing the mold, a previously machined pellet 10, made of PEEK of a color different from that of the material of which the radome will be made, is placed at the top of the nipple 3 of the male part 1 of the mold, and held in this place by the fact that it has a small cavity 11 (FIG. 2), the shape of which is complementary to that of the aforementioned stud 5, the latter therefore coming to fit tightly into this cavity, thereby keeping the machined pad 10 in place. Alternatively, the stud 5 and the cavity 11 are replaced by a temporary bonding of the patch to the male part 1.

En variante, la pastille 10 pourrait être obtenue par un procédé d'injection dans un petit moule prévu à cet effet, au lieu d'être réalisée par usinage.As a variant, the tablet 10 could be obtained by an injection process in a small mold provided for this purpose, instead of being produced by machining.

Après fermeture du moule, les composants du PEEK constitutif du radôme de la figure 2 sont injectés par la carotte d'injection 9. La partie externe de la pastille 10 est alors portée à une température suffisante pour fondre localement, de sorte que cette pastille vient se souder au corps 12 du radôme, composé de PEEK d'une autre couleur, et donc se noyer en quelque sorte dans ce corps 12 du radôme 14.After closing the mold, the components of the PEEK constituting the radome of FIG. 2 are injected by the injection core 9. The external part of the tablet 10 is then brought to a temperature sufficient to melt locally, so that this tablet comes to be welded to the body 12 of the radome, composed of PEEK of another color, and therefore to drown in a way in this body 12 of the radome 14.

Après refroidissement, démoulage, et ébavurage, on obtient finalement le radôme 14 de la figure 2, entièrement réalisé en PEEK et comportant, sur la pointe de sa surface interne 4 et en retrait par rapport à la pointe 13 de sa surface externe 8, une pastille 10 de couleur différente de celle qui constitue la partie restante du radôme 14.After cooling, demolding, and deburring, the radome 14 of FIG. 2 is finally obtained, entirely made of PEEK and comprising, on the tip of its internal surface 4 and set back with respect to the tip 13 of its external surface 8, a patch 10 of a different color from that which constitutes the remaining part of radome 14.

De façon avantageuse, la pastille 10 peut être pourvue sur sa surface cylindrique de moyens la maintenant en place, par exemple des nervures de révolution ou des dispositifs équivalents (aspérités radiales, filetage, ...) qui l'empêchent d'être éjectée si elle est mal soudée au corps 12, lorsque sa face frontale est dégagée par suite de l'érosion.Advantageously, the patch 10 can be provided on its cylindrical surface with means holding it in place, for example ribs of revolution or equivalent devices (radial asperities, thread, ...) which prevent it from being ejected if it is poorly welded to the body 12, when its front face is released as a result of erosion.

Les figures 3 à 5 illustrent le rôle d'indicateur d'érosion pluviale qui est joué par cette pastille 10. Sur ces trois figures, le radôme 14, monté sur sa base réceptrice 15, est vu de l'avant.Figures 3 to 5 illustrate the role of rain erosion indicator which is played by this patch 10. In these three figures, the radome 14, mounted on its receiving base 15, is seen from the front.

Lorsque l'érosion pluviale n'est pas suffisante pour que la pointe de la surface externe 8 du radôme 14 soit usée jusqu'à la pastille 14, le radôme se présente comme sur la figure 3, sa pointe étant alors de même couleur que la partie restante du radôme.When the rain erosion is not sufficient for the tip of the external surface 8 of the radome 14 to be worn down to the patch 14, the radome is presented as in FIG. 3, its point then being of the same color as the remaining part of the radome.

Lorsque, suite à l'érosion pluviale, l'épaisseur du radôme à sa pointe a diminué suffisamment, la pastille commence à apparaître comme dessiné en figure 4, c'est-à-dire sous un aspect granulé, avec des points de la couleur de la pastille, et des points de la couleur du radôme. Ceci est dû au fait que l'érosion due aux gouttes de pluie n'est pas réalisée de manière uniforme, mais de manière particulaire, chaque impact de goutte de pluie enlevant une petite particule de matière.When, following rain erosion, the thickness of the radome at its tip has decreased sufficiently, the pellet begins to appear as drawn in Figure 4, that is to say in a granulated appearance, with dots of color of the patch, and dots of the color of the radome. This is due to the fact that erosion due to raindrops is not carried out uniformly, but in a particulate way, each impact of raindrops removing a small particle of material.

L'érosion poursuivant son action, lorsqu'il ne reste plus de PEEK de la couleur du corps 12 du radôme sur la face extrême 15 (Figure 2) de la pastille 10, cette dernière apparaît alors totalement, dans sa couleur, comme dessiné en figure 5. Le radôme 14 doit alors être changé.The erosion continuing its action, when there is no more PEEK of the color of the body 12 of the radome on the end face 15 (Figure 2) of the patch 10, the latter then appears completely, in its color, as drawn in figure 5. The radome 14 must then be changed.

Selon une variante de l'invention, on peut disposer plusieurs pastilles, groupées dans une même zone ou réparties sous toute la surface externe à surveiller. Ces pastilles sont alors colorées de couleurs différentes, et sont de longueurs différentes, ce qui permet de déterminer différents degrés d'usure. Bien entendu, leur colorant ne doit pas nuire aux qualités diélectriques du radôme.According to a variant of the invention, several pellets can be placed, grouped in the same zone or distributed under the entire external surface to be monitored. These pellets are then colored with different colors, and are of different lengths, which makes it possible to determine different degrees of wear. Of course, their dye must not harm the dielectric qualities of the radome.

On a représenté en figure 6 un autre mode de réalisation de la pastille de l'invention. Le radôme 17 comporte à sa partie antérieure une pastille 18 de forme conique. L'axe de ce cône est perpendiculaire à la surface externe du radôme et est, dans le cas présent, confondu avec l'axe du radôme, mais il peut ne pas être confondu dans des cas où ce n'est pas l'apex du radôme qui est l'endroit soumis à l'érosion maximale. La pointe du cône peut affleurer la surface externe du radôme ou être légèrement en retrait. Bien entendu, comme précédemment, la couleur de la matière constituant la pastille est différente de celle constituant le radôme. Grâce à une telle pastille, on connaît à tout moment le degré d'usure du radôme, qui est proportionnel à la surface visible de la pastille.FIG. 6 shows another embodiment of the patch of the invention. The radome 17 has at its front part a pellet 18 of conical shape. The axis of this cone is perpendicular to the outer surface of the radome and is, in this case, confused with the axis of the radome, but it may not be confused in cases where it is not the apex of the radome which is the place subject to maximum erosion. The tip of the cone may be flush with the outer surface of the radome or be slightly recessed. Of course, as before, the color of the material constituting the pellet is different from that constituting the radome. Thanks to such a pellet, the degree of wear of the radome is known at all times, which is proportional to the visible surface of the pellet.

Comme représenté en figure 7, le radôme 19 peut comporter plusieurs pastilles, cylindriques ou coniques, disposées aux endroits les plus soumis à l'érosion. On a représenté sur cette figure trois telles pastilles, référencées 20, 21 et 22.As shown in Figure 7, the radome 19 may include several pellets, cylindrical or conical, arranged in the places most subject to erosion. This figure shows three such pellets, referenced 20, 21 and 22.

Bien entendu, les pastilles de l'invention peuvent également être utilisées pour un radôme à structure stratifiée.Of course, the pellets of the invention can also be used for a radome with a laminated structure.

L'invention peut également être mise en oeuvre pour des pièces autres que des radômes et soumises à l'usure, lorsque l'on ne peut pas déterminer directement leur épaisseur.The invention can also be implemented for parts other than radomes and subjected to wear, when their thickness cannot be determined directly.

Comme il va de soi, l'invention n'est pas limitée à l'exemple préférentiel qui vient d'être décrit. C'est ainsi qu'il est avantageux, en particulier pour ne pas perturber la réception des ondes électromagnétiques, que la pastille 10 soit réalisée en la même matière thermoplastique que le corps 12 du radôme, mais ceci n'est pas limitatif et cette pastille pourrait très bien être prévue en une matière thermoplastique d'une autre sorte. C'est ainsi également que cette pastille pourrait être maintenue en place dans le moule par un procédé d'aspiration au lieu de l'être par un moyen mécanique. C'est ainsi aussi que cette même pastille pourrait ne pas être positionnée dans le nez du radôme 14, de manière coaxiale à celui-ci, mais être plus ou moins décalée par rapport à son axe, selon en fait l'endroit d'impact maximal des gouttes de pluie. Bien entendu, dans la plupart des cas d'utilisation, la pastille est de dimensions suffisamment faibles pour ne pas influencer défavorablement l'homogénéité des qualités des pièces la contenant.It goes without saying that the invention is not limited to the preferred example which has just been described. This is how it is advantageous, in particular not to disturb the reception of electromagnetic waves, that the patch 10 is made of the same thermoplastic material as the body 12 of the radome, but this is not limiting and this patch could very well be provided in a thermoplastic material of another kind. It is also thus that this pellet could be kept in place in the mold by a suction process instead of being by mechanical means. It is thus also that this same patch could not be positioned in the nose of the radome 14, in a coaxial manner with the latter, but be more or less offset with respect to its axis, depending in fact on the place of impact. maximum raindrops. Of course, in most cases of use, the tablet is of sufficiently small dimensions not to adversely influence the uniformity of the qualities of the parts containing it.

Claims (11)

Indicateur d'usure pour une pièce à surveiller (14), caractérisé en ce qu'il est constitué par au moins une pastille (10), de couleur différente de celle de la matière dont la pièce est constituée, qui est intégrée à la structure de la pièce et qui est positionnée dans cette pièce de sorte que sa partie devenue visible suite à l'usure de la pièce donne une indication du degré d'usure.Wear indicator for a part to be monitored (14), characterized in that it consists of at least one patch (10), of a color different from that of the material of which the part is made, which is integrated into the structure of the part and which is positioned in this part so that its part which has become visible following wear of the part gives an indication of the degree of wear. Indicateur d'usure selon la revendication 1, caractérisé en ce que la pastille a une forme cylindrique.Wear indicator according to claim 1, characterized in that the patch has a cylindrical shape. Indicateur d'usure selon la revendication 2, caractérisé en ce que la pastille est pourvue sur sa surface cylindrique de moyens la maintenant en place.Wear indicator according to claim 2, characterized in that the pad is provided on its cylindrical surface with means holding it in place. Indicateur d'usure selon l'une des revendications précédentes, caractérisé en ce qu'il comporte plusieurs pastilles de longueurs et de couleurs différentes.Wear indicator according to one of the preceding claims, characterized in that it comprises several pads of different lengths and colors. Indicateur d'usure selon la revendication 1, caractérisé en ce que la pastille a une forme conique.Wear indicator according to claim 1, characterized in that the patch has a conical shape. Indicateur d'usure selon l'une des revendications précédentes, caractérisé en ce que la pièce à surveiller est un radôme.Wear indicator according to one of the preceding claims, characterized in that the part to be monitored is a radome. Indicateur d'usure selon la revendication 6, caractérisé en ce que le radôme est en matière thermoplastique.Wear indicator according to claim 6, characterized in that the radome is made of thermoplastic material. Indicateur d'usure selon la revendication 6 ou 7, caractérisé en ce que la pastille (10) est placée dans le nez du radôme (14) et coaxialement avec celui-ci.Wear indicator according to claim 6 or 7, characterized in that the patch (10) is placed in the nose of the radome (14) and coaxially with it. Indicateur d'usure selon l'une des revendications 6 à 8, caractérisé en ce que la pastille (10) est réalisée dans la même matière thermoplastique que le radôme (14).Wear indicator according to one of claims 6 to 8, characterized in that the patch (10) is made of the same thermoplastic material as the radome (14). Indicateur d'usure selon l'une des revendications 6 à 9, caractérisé en ce que la pastille (10) est munie, du côté de la face interne (4) du radôme, d'une cavité (11) qui est complémentaire d'un téton (5) de retenue de la pastille (10) prévu sur la partie mâle (1) du moule d'injection du radôme.Wear indicator according to one of claims 6 to 9, characterized in that the patch (10) is provided, on the side of the internal face (4) of the radome, with a cavity (11) which is complementary to a pin (5) for retaining the pellet (10) provided on the male part (1) of the radome injection mold. Procédé de fabrication d'un radôme thermoplastique muni d'un indicateur d'érosion selon l'une des revendications 6 à 10, caractérisé en ce qu'il consiste : . à fabriquer tout d'abord une pastille thermoplastique (10) de couleur différente de celle du corps (12) du radôme, mais moins épaisse que celui-ci, . à rapporter cette pastille (10) sur la partie mâle (1, 3) du moule d'injection du radôme, à l'endroit (5) correspondant à sa position future dans le corps (12) du radôme, . puis, après avoir refermé le moule, à injecter dans celui-ci la matière thermoplastique, ladite pastille s'intégrant alors totalement, par fusion partielle, au corps (12) de ce radôme. Method of manufacturing a thermoplastic radome provided with an erosion indicator according to one of claims 6 to 10, characterized in that it consists: . firstly manufacturing a thermoplastic pellet (10) of a different color from that of the body (12) of the radome, but thinner than the latter, . to add this patch (10) to the male part (1, 3) of the radome injection mold, at the location (5) corresponding to its future position in the body (12) of the radome, . then, after having closed the mold, to inject therein the thermoplastic material, said pellet then integrating fully, by partial melting, into the body (12) of this radome.
EP19960402117 1995-10-06 1996-10-04 Wear indicator, in particular for thermoplastic radome and method of fabrication Expired - Lifetime EP0767509B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9511794 1995-10-06
FR9511794A FR2739725B1 (en) 1995-10-06 1995-10-06 EROSION INDICATOR FOR THERMOPLASTIC RADOME AND MANUFACTURING METHOD

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EP0767509A1 true EP0767509A1 (en) 1997-04-09
EP0767509B1 EP0767509B1 (en) 2001-07-25

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DE (1) DE69614061T2 (en)
FR (1) FR2739725B1 (en)

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US8002659B2 (en) * 2002-08-22 2011-08-23 The Gates Corporation Transmission belt and indication apparatus for indicating the end of life of transmission belt
CN113659330A (en) * 2021-08-06 2021-11-16 苏州市新胜佳科技有限公司 5G base station aging-resistant antenna housing and forming process method thereof

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8002659B2 (en) * 2002-08-22 2011-08-23 The Gates Corporation Transmission belt and indication apparatus for indicating the end of life of transmission belt
CN113659330A (en) * 2021-08-06 2021-11-16 苏州市新胜佳科技有限公司 5G base station aging-resistant antenna housing and forming process method thereof
CN113659330B (en) * 2021-08-06 2023-08-15 苏州市新胜佳科技有限公司 5G base station aging-resistant radome and molding process method thereof

Also Published As

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EP0767509B1 (en) 2001-07-25
DE69614061T2 (en) 2001-11-29
FR2739725B1 (en) 1997-11-07
DE69614061D1 (en) 2001-08-30
FR2739725A1 (en) 1997-04-11

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