EP0191664A1 - Envelope under vacuum for an X-ray image intensifier tube - Google Patents

Envelope under vacuum for an X-ray image intensifier tube Download PDF

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Publication number
EP0191664A1
EP0191664A1 EP86400055A EP86400055A EP0191664A1 EP 0191664 A1 EP0191664 A1 EP 0191664A1 EP 86400055 A EP86400055 A EP 86400055A EP 86400055 A EP86400055 A EP 86400055A EP 0191664 A1 EP0191664 A1 EP 0191664A1
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EP
European Patent Office
Prior art keywords
aluminum
central body
window
brazed
vacuum envelope
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Granted
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EP86400055A
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German (de)
French (fr)
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EP0191664B1 (en
Inventor
Gilbert Colomb
Maurice Verat
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/86—Vessels; Containers; Vacuum locks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
    • H01J9/26—Sealing together parts of vessels
    • H01J9/263—Sealing together parts of vessels specially adapted for cathode-ray tubes

Definitions

  • the present invention relates to a vacuum envelope for an X-ray image intensifier tube.
  • Vacuum envelopes for radiological image intensifier tubes essentially comprise a central body of revolution, the ends of which are terminated by an entry window intended for the passage of the radiation to be intensified and by an exit window for visible radiation.
  • entry windows were usually made of glass, which posed few problems of sealing with the central body even when it was made partly of ferrous metal, because glass-metal seals are well known to those skilled in the art.
  • the use of glass for entry windows poses a number of problems.
  • the absorption of radiation, in particular X-ray radiation, and the diffusion of the radiation are very important and increase with the size of the tube.
  • the use of a glass entry window therefore results in a considerable limitation of the performance of the tube such as contrast, resolution, etc.
  • the tube inlet screen being convex for the purposes of electronic optics, if a concave window is used, the tube must be lengthened by an amount equal to the arrow in the inlet window. However, this arrow is all the more important as the field of entry of the IIR is larger.
  • the tube entry plane moves away from the entry screen. Due to the conical projection from the focal point of the X-ray tube, the actual input field of the tube, measured in the input plane, is reduced compared to the useful field of the input screen.
  • the sealing between the window and the central body can be carried out by thermo-compression welding. There is diffusion in the solid state of the aluminum of the window and of a metallic coating deposited on the ferrous metal of the central body, at a temperature lower than that of their fusion. The contact surfaces must be flat, thereby excluding the type of cylinder-on-cylinder geometry.
  • the convex aluminum or aluminum alloy window has an annular peripheral flange and the assembly between the window and the body requires either that the body has an annular flange perpendicular to the axis of the tube, or use of an L-shaped or S-shaped connection ring
  • Another solution of the prior art consists in using a convex window having a copper layer plated on an aluminum layer in which the copper layer is removed in the part subjected to radiation and the aluminum layer is removed on the periphery of a flat surrounding the convex cap, reserving a localized overlap of the two layers.
  • the copper is then welded by electric arc welding along a lip resealed on the central metallic body which can be made of stainless steel.
  • the object of the present invention is to provide a new vacuum envelope structure for an X-ray image intensifier tube comprising a window which does not have the drawbacks of prior art windows.
  • the object of the present invention is also to provide a new vacuum envelope structure for an X-ray image intensifier tube which is easy and quick to produce.
  • the present invention relates to a vacuum envelope for an X-ray image intensifier tube comprising an inlet window secured to a central body of ferrous alloy, characterized in that the inlet window is made of an aluminum alloy, and of series 5000 magnesium and is embedded in an aluminum part, of the 1000 series, to which it is welded, this part being brazed by brazing with the aluminum-silicon or aluminum-silicon-magnesium eutectic to the central body.
  • Figure 1 is a longitudinal sectional view of a radiological image intensifier tube comprising a vacuum envelope according to an embodiment of the invention.
  • the part 1 designates a part of the central body of revolution. This part consists of a glass cylinder ending in an exit window also made of glass.
  • the glass cylinder is welded to an intermediate ring 2.
  • This intermediate ring is made of iron or an iron alloy, preferably an iron-nickel-cobalt alloy such as the Dilver or an iron-nickel alloy such as the Carpenter .
  • the intermediate ring is provided to facilitate welding on the glass cylinder in particular, when the rest of the central body of revolution 3 is made of stainless steel.
  • the parts 2 and 3 may constitute only one piece when they are made of the same material.
  • the main elements constituting the radiological image intensifier tube such as the scintillator and the photocathode, which have the reference 4, the acceleration and focusing electrodes 5, have been shown diagrammatically inside the envelope. the output screen 8, and the last electrode or anode 9.
  • the entry window 10 is made of an aluminum and magnesium alloy of the 5000 series, such as for example 5086 or AG 4 MC.
  • the series in question is defined, like many others, by American standards well known to specialists. These alloys are rigid enough to withstand the mechanical stresses due to the difference in pressures existing between the inside and the outside of the tube.
  • THE G. MC is the most efficient alloy from a mechanical point of view for this application.
  • the window 10 made of aluminum and magnesium alloy it is not possible to directly solder the window 10 made of aluminum and magnesium alloy to the ferrous alloy of the central body of revolution because the melting range of the window, for example in the case where it is made of AG 4 MC, extends from 580 to 6 4 0 °, that is to say in the brazing interval of the eutectic AI - Si at 89% which allows the brazing between aluminum and its alloys and ferrous alloys.
  • the entry window 10 therefore fits into an aluminum part 11 of the 1000 series, such as for example the 1050 A or A5, as can be seen in FIG. 1.
  • the window 10 and the part 11 are welded, for example by TIG (Tungsten Inert Gas) welding in alternating current and under a helium atmosphere, to obtain a good vacuum seal.
  • TIG Tungsten Inert Gas
  • FIG. 1 it can be seen that a groove is provided in the part 11 to allow the part 10 to be embedded.
  • the part 11 which is of aluminum of type A s for example, can be brazed to a part 12 of ferrous alloy which forms part of the central body of the tube. It is an aluminum-silicon eutectic solder, around 585 ° C or an aluminum-silicon magnesium eutectic solder. This solder makes it possible to make the parts 11 and 12 integral in a vacuum-tight manner.
  • the window 10 is then fitted into the window and welded to the part 11. Then the window 10 and the parts 11 and 12 are assembled to the rest of the central body of ferrous alloy, for example by Argon-Arc welding.
  • the machining must be done with some precautions to be safe for soldering.
  • the part 12 is machined before being brazed to the part 11.
  • a method of manufacturing a vacuum envelope according to the invention therefore consists in assembling a part 11 of aluminum of type A 5 to a part 1 2 of ferrous alloy.
  • This process is simple, fast and easily industrializable.
  • FIGS 2 to 5 show various alternative embodiments of the vacuum envelope according to the invention.
  • FIG. 2 shows in more detail the embodiment of FIG. 1.
  • the piece 11 of type A aluminum 5 is brazed to a piece 12 of ferrous alloy, of substantially cylindrical shape, and terminated by a circular crown 13.
  • the circular crown 13 is brazed to the piece 11, which has substantially the shape of a circular crown.
  • This brazing consists in melting a "joint" 1 4 of brazing, at a suitable temperature, by all known means, for example in an oven, by high frequency losses in the parts to be assembled, by electronic bombardment. This fusion can take place under a controlled, reducing or neutral atmosphere, or under vacuum.
  • This brazing can also be carried out by indirect HF induction as described below.
  • the two surfaces to come into contact receive a layer of aluminum solder.
  • the assembly is placed on a metal mandrel surmounted by a support plate made of asbestos cement and preheating to 180 ° C is carried out .
  • a ferro-magnetic steel disc 0.6 mm thick is deposited on the assembly, which is commonly designated by the term "susceptor".
  • the suceptor is heated by induction and transmits heat by conduction.
  • the melting temperature of the Aluminum-Silicon eutectic It regulates the melting temperature of the Aluminum-Silicon eutectic by placing it at the Curie point of the material that constitutes it.
  • the brazing operation takes place while the assembly is tightened under high pressure.
  • the duration of this pressurization and that of the heating of the susceptor are determined according to the dimensions of the parts. On average, the duration of pressurization is more than double the duration of heating of the susceptor.
  • the temperature is around 580 ° C.
  • the susceptor is removed and the two brazed parts are immersed in water at room temperature, which makes it possible to remove a large part of the flux by detachment. The rest of the flux is removed by mechanical action and by chemical treatment.
  • FIGS 3, 4 and 5 show various variants of the envelope according to the invention.
  • the part 11 has a substantially conical shape, with a slight slope.
  • the central body ends in a part 12, of substantially conical shape, with a slight slope.
  • the solder 14 is distributed between the two surfaces facing the parts 11 and 12, which are substantially conical, and have a slight slope.
  • the part 11 has substantially the shape of a circular crown and the central body ends in a cylindrical part 12, the end of which is brazed to the part 11.
  • FIG. 5 represents another variant of the envelope according to the invention in which said part 11 has substantially the shape of a circular crown.
  • the central body ends in a substantially cylindrical part 12 to which another substantially cylindrical part 15 is welded, ending in a circular ring 16 brazed to said part 11.
  • This variant allows brazing to be carried out without significantly modifying the parts usually used to make the intensifiers.

Abstract

Selon l'invention, cette enveloppe comporte une fenêtre d'entrée (10), solidaire d'un corps central (2, 3, 12) en alliage ferreux, qui est réalisée en un alliage d'aluminium et de magnésium de la série 5000. Cette fenêtre d'entrée est encastrée dans une pièce en aluminium (11), de la série 1000, à laquelle elle est soudée. La pièce en aluminium (11) est brasée par brasure à l'eutectique aluminium-silicium ou aluminium-silicium-magnésium au corps central (12).According to the invention, this envelope comprises an entry window (10), integral with a central body (2, 3, 12) of ferrous alloy, which is made of an aluminum and magnesium alloy of the 5000 series This entry window is embedded in an aluminum piece (11), of the 1000 series, to which it is welded. The aluminum part (11) is brazed by brazing with the aluminum-silicon or aluminum-silicon-magnesium eutectic to the central body (12).

Description

La présente invention concerne une enveloppe sous vide pour tube intensificateur d'images radiologiques.The present invention relates to a vacuum envelope for an X-ray image intensifier tube.

Les enveloppes sous vide pour tubes intensificateurs d'images radiologiques comportent essentiellement un corps central de révolution dont les extrémités sont terminées par une fenêtre d'entrée destinée au passage du rayonnement à intensifier et par une fenêtre de sortie du rayonnement visible.Vacuum envelopes for radiological image intensifier tubes essentially comprise a central body of revolution, the ends of which are terminated by an entry window intended for the passage of the radiation to be intensified and by an exit window for visible radiation.

Jusqu'à ces demiers temps, les fenêtres d'entrée étaient habituellement réalisées en verre, ce qui posait peu de problèmes de scellement avec le corps central même lorsque celui-ci était réalisé en partie en métal ferreux, car les scellements verre-métal sont bien connus de l'homme de l'art. Toutefois, l'utilisation du verre pour les fenêtres d'entrée pose un certain nombre de problèmes. Ainsi, l'absorption du rayonnement, en particulier du rayonnement X, et la diffusion du rayonnement sont très importantes et augmentent avec la taille du tube. L'utilisation d'une fenêtre d'entrée en verre entraîne donc une limitation considérable des performances du tube telles que le contraste, la résolution...Until recently, entry windows were usually made of glass, which posed few problems of sealing with the central body even when it was made partly of ferrous metal, because glass-metal seals are well known to those skilled in the art. However, the use of glass for entry windows poses a number of problems. Thus, the absorption of radiation, in particular X-ray radiation, and the diffusion of the radiation are very important and increase with the size of the tube. The use of a glass entry window therefore results in a considerable limitation of the performance of the tube such as contrast, resolution, etc.

Pour remédier à ces inconvénients, on a proposé de réaliser des fenétres d'entrée en métal perméable au rayonnement à intensifier.To overcome these drawbacks, it has been proposed to produce entry windows made of metal permeable to the radiation to be intensified.

Ainsi on a proposé de réaliser des fenêtres d'entrée concaves en titane ou en acier. Cette forme de fenêtre d'entrée conduit à de faibles épaisseurs de métal et donne des fenêtres peu absorbantes, mais néanmoins suffisamment résistantes pour supporter la pression atmosphérique. Une épaisseur de 250 micromètres de titane permet la transmission d'environ 88 % du flux de rayons X et une épaisseur de 100 micromètres d'acier inoxydable permet la transmission d'environ 88 % du flux de rayons X.Thus, it has been proposed to produce concave entry windows in titanium or in steel. This form of entry window leads to small thicknesses of metal and gives windows that are not very absorbent, but nevertheless sufficiently resistant to withstand atmospheric pressure. A thickness of 250 micrometers of titanium allows the transmission of approximately 88% of the X-ray flux and a thickness of 100 micrometers of stainless steel allows the transmission of approximately 88% of the X-ray flux.

Cependant la forme concave de ces fenêtres entraîne lors de la mise sous vide divers inconvénients.However, the concave shape of these windows leads to various drawbacks during vacuuming.

L'écran d'entrée du tube étant convexe pour les besoins de l'optique électronique, il faut si l'on utilise une fenêtre concave allonger le tube d'une quantité égale à la flèche de la fenêtre d'entrée. Or cette flèche est d'autant plus importante que le champ d'entrée de l'IIR est plus grand.The tube inlet screen being convex for the purposes of electronic optics, if a concave window is used, the tube must be lengthened by an amount equal to the arrow in the inlet window. However, this arrow is all the more important as the field of entry of the IIR is larger.

Le plan d'entrée du tube s'éloigne de l'écran d'entrée. A cause de la projection conique à partir du foyer du tube générateur de rayons X, le champ d'entrée réel du tube, mesuré dans le plan d'entrée, se trouve réduit par rapport au champ utile de l'écran d'entrée.The tube entry plane moves away from the entry screen. Due to the conical projection from the focal point of the X-ray tube, the actual input field of the tube, measured in the input plane, is reduced compared to the useful field of the input screen.

Enfin, à cause de la projection sur une surface convexe, à champ d'entrée égal, la distorsion augmente.Finally, due to the projection on a convex surface, with an equal input field, the distortion increases.

On a aussi proposé de réaliser des fenêtres en aluminium ou en alliage d'aluminium de forme convexe. Cette forme permet une bonne résistance mécanique de la pièce soumise à la pression atmosphérique. Pour un diamètre de 230 mm, son épaisseur peut être de 0,8 mm seulement La diffusion est alors très faible et 94 % des rayons x sont transmis. Dans ce cas, différentes techniques sont utilisées pour réaliser le scellement de la fenêtre sur le corps central.It has also been proposed to make aluminum or aluminum alloy windows of convex shape. This shape allows good mechanical resistance of the part subjected to atmospheric pressure. For a diameter of 230 mm, its thickness can be only 0.8 mm. The diffusion is then very weak and 94% of the x-rays are transmitted. In this case, different techniques are used to achieve the sealing of the window on the central body.

Le scellement entre la fenêtre et le corps central peut être réalisé par soudage par thermo-compression. Il y a diffusion à l'état solide de l'aluminium de la fenêtre et d'un revêtement métallique déposé sur le métal ferreux du corps central, à une température inférieure à celle de leur fusion. Il faut que les surfaces de contact soient planes, excluant de ce fait le type de géometrie cylindre sur cylindre. Dans ce cas, la fenêtre convexe en aluminium ou en alliage d'aluminium comporte un flasque périphérique annulaire et l'assemblage entre la fenêtre et le corps nécessite soit que le corps comporte un flasque annulaire perpendiculaire à l'axe du tube, soit l'utilisation d'un anneau de connexion en forme de L ou de S.The sealing between the window and the central body can be carried out by thermo-compression welding. There is diffusion in the solid state of the aluminum of the window and of a metallic coating deposited on the ferrous metal of the central body, at a temperature lower than that of their fusion. The contact surfaces must be flat, thereby excluding the type of cylinder-on-cylinder geometry. In this case, the convex aluminum or aluminum alloy window has an annular peripheral flange and the assembly between the window and the body requires either that the body has an annular flange perpendicular to the axis of the tube, or use of an L-shaped or S-shaped connection ring

Ainsi, si cette technologie permet d'obtenir des tubes de longueur optimisée, elle présente l'inconvénient d'accroître considérablement le diamètre hors-tout du tube. Un autre inconvénient de cette technologie est qu'il faut ajuster divers paramètres tels que la température, la pression mécanique exercée, et le temps de maintien en contact des pièces. Cela nécessite du temps et de l'énergie, et rend le procédé coûteux industriellement dans sa mise en oeuvre et son exploitation.Thus, if this technology makes it possible to obtain tubes of optimized length, it has the drawback of considerably increasing the overall diameter of the tube. Another disadvantage of this technology is that it is necessary to adjust various parameters such as the temperature, the mechanical pressure exerted, and the time of keeping in contact with the parts. This requires time and energy, and makes the process industrially expensive in its implementation and operation.

Une autre solution de l'art antérieur consiste à utiliser une fenêtre de forme convexe comportant une couche de cuivre plaquée sur une couche d'aluminium dans laquelle la couche de cuivre est enlevée dans la partie soumise au rayonnement et la couche d'aluminium est enlevée sur la périphérie d'un méplat entourant la calotte convexe, en réservant un recouvrement localisé des deux couches. Le cuivre est ensuite soudé par soudage à l'arc électrique le long d'une lèvre réslisée sur le corps central métallique qui peut être en acier inoxydable.Another solution of the prior art consists in using a convex window having a copper layer plated on an aluminum layer in which the copper layer is removed in the part subjected to radiation and the aluminum layer is removed on the periphery of a flat surrounding the convex cap, reserving a localized overlap of the two layers. The copper is then welded by electric arc welding along a lip resealed on the central metallic body which can be made of stainless steel.

On retrouve dans ce cas les mêmes problèmes de diamètre hors tout du tube qu'avec le soudage par thermo-compression. D'autre part, il est difficile d'obtenir un matériau à deux couches fabriqué industriellement et qui présente toujours la même qualité d'ahérence réciproque avec étanchéité au vide. En outre, il faut réaliser l'enlèvement du métal avant de pouvoir réaliser le soudage.We find in this case the same problems of overall diameter of the tube as with thermocompression welding. On the other hand, it is difficult to obtain a two-layer material manufactured industrially and which always exhibits the same quality of reciprocal appearance with vacuum tightness. In addition, the metal must be removed before welding can be carried out.

La présertte invention a pour but de fournir une nouvelle structure d'enveloppe sous vide pour tube intensificateur d'images radiologiques comportant une fenêtre qui ne présente pas les inconvénients des fenêtres de fart antérieur.The object of the present invention is to provide a new vacuum envelope structure for an X-ray image intensifier tube comprising a window which does not have the drawbacks of prior art windows.

La présente invention a aussi pour but une nouvelle structure d'enveloppe sous vide pour tube intensificateur d'images radiologiques qui soit facile et rapide à réaliser.The object of the present invention is also to provide a new vacuum envelope structure for an X-ray image intensifier tube which is easy and quick to produce.

La présente invention concerne une enveloppe sous vide pour tube intensificateur d'images radiologiques comportant une fenêtre d'entrée solidaire d'un corps central en alliage ferreux, caractérisée en ce que la fenêtre d'entrée est réalisée en un alliage d'aluminium, et de magnésium de la série 5000 et est encastrée dans une pièce en aluminium, de la série 1000, à laquelle elle est soudée, cette pièce étant brasée par brasure à l'eutectique aluminium-silicium ou aluminium-silicium-magnésium au corps central.The present invention relates to a vacuum envelope for an X-ray image intensifier tube comprising an inlet window secured to a central body of ferrous alloy, characterized in that the inlet window is made of an aluminum alloy, and of series 5000 magnesium and is embedded in an aluminum part, of the 1000 series, to which it is welded, this part being brazed by brazing with the aluminum-silicon or aluminum-silicon-magnesium eutectic to the central body.

D'autres objets, caractéristiques et résultats de l'inven- fion ressortiront de la description suivante, donnée à titre d'exemple non limitatif et illustrée par les figures annexées qui représentent ;

  • - la figure 1, une vue en coupe longitudinale d'un tube intensificateur d'images radiologiques comportant une enveloppe sous vide selon un mode de réalisation de l'invention
  • - les figures 2 à 5, des vues en coupe illustrant divers modes de réalisation de l'enveloppe sous vide selon l'inven- fion.
Other objects, characteristics and results of the invention will emerge from the following description, given by way of nonlimiting example and illustrated by the appended figures which represent;
  • - Figure 1, a longitudinal sectional view of a radiological image intensifier tube comprising a vacuum envelope according to an embodiment of the invention
  • - Figures 2 to 5, sectional views illustrating various embodiments of the vacuum envelope according to the invention.

Sur les différentes figures, les mêmes repères désignent les mêmes éléments, mais. pour des raisons de clarté, les cotes et proportions des divers éléments ne sont pas respectées.In the different figures, the same references designate the same elements, but. for reasons of clarity, the dimensions and proportions of the various elements are not respected.

La figure 1 est une vue en coupe longitudinale d'un tube intensificateur d'images radiologiques comportant une enveloppe sous vide selon un mode de réalisation de l'invention.Figure 1 is a longitudinal sectional view of a radiological image intensifier tube comprising a vacuum envelope according to an embodiment of the invention.

On désigne par la référence 1 une partie du corps central de révolution. Cette partie se compose d'un cylindre en verre se terminant par une fenêtre de sortie également en verre.The part 1 designates a part of the central body of revolution. This part consists of a glass cylinder ending in an exit window also made of glass.

Le cylindre en verre est soudé à un anneau intermédiaire 2. Cet anneau intermédiaire est réalisé en fer ou en alliage de fer, de préférence en un alliage fer-nickel- cobalt tel que le Dilver ou en un alliage fer-nickel tel que le Carpenter.The glass cylinder is welded to an intermediate ring 2. This intermediate ring is made of iron or an iron alloy, preferably an iron-nickel-cobalt alloy such as the Dilver or an iron-nickel alloy such as the Carpenter .

L'anneau intermédiaire est prévu pour faciliter le soudage sur le cylindre en verre notamment, lorsque le reste du corps central de révolution 3 est réalisé en acier inoxydable. Toutefois, il est évident pour l'homme de l'art que les pièces 2 et 3 peuvent ne constituer qu'une seule pièce lorsqu'elles sont réalisées dans le même matériau.The intermediate ring is provided to facilitate welding on the glass cylinder in particular, when the rest of the central body of revolution 3 is made of stainless steel. However, it is obvious to those skilled in the art that the parts 2 and 3 may constitute only one piece when they are made of the same material.

On a schématisé à l'intérieur de l'enveloppe les principaux éléments constituant le tube intensificateur d'images radiologiques tels que le scintillateur et la photocathode, qui portent la référence 4, les électrodes 5, 6, 7 d'accélération et de focalisation, t'écran de sortie 8, et la demière électrode ou anode 9.The main elements constituting the radiological image intensifier tube, such as the scintillator and the photocathode, which have the reference 4, the acceleration and focusing electrodes 5, have been shown diagrammatically inside the envelope. the output screen 8, and the last electrode or anode 9.

Selon l'invention, la fenêtre d'entrée 10 est réalisée en un alliage d'aluminium et de magnésium de la série 5000, comme par exemple le 5086 ou AG4 MC. La série dont il est question est définie comme de nombreuses autres par des normes américaines bien connues des spécialistes. Ces alliages sont suffisamment rigides pour supporter les efforts mécaniques dus à la différence de pressions existant entre l'intérieur et l'extérieur du tube. L'AG. MC est l'alliage le plus performant d'un point de vue mécanique pour cette application.According to the invention, the entry window 10 is made of an aluminum and magnesium alloy of the 5000 series, such as for example 5086 or AG 4 MC. The series in question is defined, like many others, by American standards well known to specialists. These alloys are rigid enough to withstand the mechanical stresses due to the difference in pressures existing between the inside and the outside of the tube. THE G. MC is the most efficient alloy from a mechanical point of view for this application.

Il n'est pas possible de braser directement la fenêtre 10 en alliage d'aluminium et de magnésium à l'alliage ferreux du corps central de révolution car la plage de fusion de la fenêtre, par exemple dans le cas où elle est réalisée en AG4MC, s'étend de 580 à 640°, c'est-à-dire dans l'intervalle de brasage de t'eutectique AI - Si à 89 % qui permet le brasage entre l'aluminium et ses alliages et les alliages ferreux.It is not possible to directly solder the window 10 made of aluminum and magnesium alloy to the ferrous alloy of the central body of revolution because the melting range of the window, for example in the case where it is made of AG 4 MC, extends from 580 to 6 4 0 °, that is to say in the brazing interval of the eutectic AI - Si at 89% which allows the brazing between aluminum and its alloys and ferrous alloys.

La fenêtre d'entrée 10 vient donc s'encastrer dans une pièce 11 en aluminium de la série 1000, comme par exemple le 1050 A ou A5, comme on peut le voir sur la figure 1. De plus, la fenêtre 10 et la pièce 11 sont soudées, par exemple par soudure TIG (Tungsten Inert Gaz) en courant alternatif et sous atmosphère d'hélium, pour obtenir une bonne étanchéité au vide. Sur la figure 1, on voit qu'une gorge est prévue dans la pièce 11 pour permettre l'encastrement de la pièce 10.The entry window 10 therefore fits into an aluminum part 11 of the 1000 series, such as for example the 1050 A or A5, as can be seen in FIG. 1. In addition, the window 10 and the part 11 are welded, for example by TIG (Tungsten Inert Gas) welding in alternating current and under a helium atmosphere, to obtain a good vacuum seal. In FIG. 1, it can be seen that a groove is provided in the part 11 to allow the part 10 to be embedded.

La pièce 11, qui est en aluminium du type As par exemple, peut être brasée à une pièce 12 en alliage ferreux qui fait partie du corps central du tube. Il s'agit d'une brasure à l'eutectique aluminium-silicium, vers 585°C ou d'une brasure à l'eutectique aluminium-silicium magnésium. Cette brasure permet de rendre les pièces 11 et 12 solidaires de manière étanche au vide.The part 11, which is of aluminum of type A s for example, can be brazed to a part 12 of ferrous alloy which forms part of the central body of the tube. It is an aluminum-silicon eutectic solder, around 585 ° C or an aluminum-silicon magnesium eutectic solder. This solder makes it possible to make the parts 11 and 12 integral in a vacuum-tight manner.

On encastre ensuite la fenêtre 10 et on la soude sur la pièce 11. Puis, on assemble la fenêtre 10, et les pièces 11 et 12 au reste du corps central en alliage ferreux, par exemple par soudure Argon-Arc.The window 10 is then fitted into the window and welded to the part 11. Then the window 10 and the parts 11 and 12 are assembled to the rest of the central body of ferrous alloy, for example by Argon-Arc welding.

On peut aussi usiner la pièce 11 pour que la fenêtre 10 puisse s'y encastrer alors que les pièces 11 et 12 sont brasées. L'usinage doit se faire avec quelques précautions pour être sans risque pour la brasure. La pièce 12 est usinée avant d'être brasée à la pièce 11.One can also machine the part 11 so that the window 10 can be embedded therein while the parts 11 and 12 are brazed. The machining must be done with some precautions to be safe for soldering. The part 12 is machined before being brazed to the part 11.

Un procédé de fabrication d'une enveloppe sous vide selon l'invention consiste donc à assembler une pièce 11 en aluminium de type A5 à une pièce 12 en alliage ferreux.A method of manufacturing a vacuum envelope according to the invention therefore consists in assembling a part 11 of aluminum of type A 5 to a part 1 2 of ferrous alloy.

Ce procédé est simple, rapide et facilement industrialisable.This process is simple, fast and easily industrializable.

Les figures 2 à 5 montrent diverses variantes de réalisation de l'enveloppe sous vide selon l'invention.Figures 2 to 5 show various alternative embodiments of the vacuum envelope according to the invention.

La figure 2 reprend de façon plus détaillée le mode de réalisation de la figure 1.FIG. 2 shows in more detail the embodiment of FIG. 1.

Dans ce cas, la pièce 11 en aluminium de type A5 est brasée à une pièce 12 en alliage ferreux, de forme sensiblement cylindrique, et terminée par une couronne circulaire 13. On brase la couronne circulaire 13 à la pièce 11, qui a sensiblement la forme d'une couronne circulaire.In this case, the piece 11 of type A aluminum 5 is brazed to a piece 12 of ferrous alloy, of substantially cylindrical shape, and terminated by a circular crown 13. The circular crown 13 is brazed to the piece 11, which has substantially the shape of a circular crown.

Dans le cas des figures 2 à 5, il s'agit bien sûr comme dans le cas de la figure 1 d'une brasure à l'eutectique aluminium-silicium ou d'une brasure à l'eutectique aluminium-silicium-magnésium.In the case of FIGS. 2 to 5, it is of course as in the case of FIG. 1 of a brazing with the aluminum-silicon eutectic or of a brazing with the aluminum-silicon-magnesium eutectic.

Cette brasure consiste à faire fondre un "joint" 14 de brasure, à température convenable, par tous les moyens connus, par exemple dans un four, par pertes haute fréquence dans les pièces à assembler, par bombardement électronique.... Cette fusion peut avoir lieu sous atmosphère contrôlée, réductrice ou neutre, ou sous vide.This brazing consists in melting a "joint" 1 4 of brazing, at a suitable temperature, by all known means, for example in an oven, by high frequency losses in the parts to be assembled, by electronic bombardment. This fusion can take place under a controlled, reducing or neutral atmosphere, or under vacuum.

Cette brasure peut également être réalisée par induction HF indirecte comme décrit ci-après.This brazing can also be carried out by indirect HF induction as described below.

Les deux surfaces devant entrer en contact reçoivent une couche de brasure à l'aluminium. On peut utiliser, par exemple, de la brasure de 200 micromètres de granulométrie, à raison de 1 à 1,2 g par dm' et une couche de flux en mélange eau-alcool à 10 %, en utilisant un volume de poudre pour 2 volumes de liquide, à raison de 0,8 à 1g par dm2. L'ensemble est mis en place sur un mandrin en métal surmonté d'une plaque d'appui en ciment d'amiante et un préchauffage à 180°C est effectué. On dépose sur l'ensemble un disque d'acier ferro-magnétique de 0,6mm d'épaisseur, que l'on désigne couramment par le terme de "susceptor". Le suceptor est chauffé par induction et transmet la chaleur par conduction. Il permet de réguler la température de fusion de l'eutectique Aluminium-Silicium en se plaçant au point de Curie du matériau qui le constitue. L'opération de brasage a lieu pendant que l'ensemble est serré sous forte pression. La durée de cette mise sous pression et celle du chauffage du susceptor sont déterminées en fonction des dimensions des pièces. En moyenne, la durée de la mise sous pression est supérieure au double de la durée du chauffage du susceptor. La température est de l'ordre de 580°C. Vers 450°C environ, on enlève le susceptor et les deux pièces brasées sont plongées dans l'eau à la température ambiante ce qui permet d'éliminer par décollement une grande partie du flux. Le restant du flux est éliminé par action mécanique et par traitement chimique.The two surfaces to come into contact receive a layer of aluminum solder. One can use, for example, brazing of 200 micrometers of granulometry, at a rate of 1 to 1.2 g per dm 'and a layer of flux in 10% water-alcohol mixture, using a volume of powder for 2 volumes of liquid, at a rate of 0.8 to 1g per dm 2. The assembly is placed on a metal mandrel surmounted by a support plate made of asbestos cement and preheating to 180 ° C is carried out . A ferro-magnetic steel disc 0.6 mm thick is deposited on the assembly, which is commonly designated by the term "susceptor". The suceptor is heated by induction and transmits heat by conduction. It regulates the melting temperature of the Aluminum-Silicon eutectic by placing it at the Curie point of the material that constitutes it. The brazing operation takes place while the assembly is tightened under high pressure. The duration of this pressurization and that of the heating of the susceptor are determined according to the dimensions of the parts. On average, the duration of pressurization is more than double the duration of heating of the susceptor. The temperature is around 580 ° C. At around 450 ° C, the susceptor is removed and the two brazed parts are immersed in water at room temperature, which makes it possible to remove a large part of the flux by detachment. The rest of the flux is removed by mechanical action and by chemical treatment.

On peut se dispenser du flux de brasage toujours difficile à éliminer en réalisant le brasage sous vide. Dans ce cas, on utilise un eutectique temaire en aluminium-silicium-magnésium.We can dispense with the brazing flux which is always difficult to eliminate by performing vacuum brazing. In this case, an aluminum-silicon-magnesium eutectic is used.

Lorsqu'elles sont brasées les pièces subissent diverses dilatations. Pour leur donner plus de souplesse pendant l'opération de brasage, on peut réaliser des gorges ou des évidements sur les pièces à braser. On peut utiliser des frettes pour compenser les différences de dilatation entre les deux matériaux brasés. Par exemple, on peut disposer contre la pièce 11, du côté où elle n'est pas en contact avec la pièce 12, une pièce dans le même matériau que la pièce 12When brazed, the pieces undergo various expansions. To give them more flexibility during the brazing operation, grooves or recesses can be made on the parts to be brazed. Frets can be used to compensate for the differences in expansion between the two brazed materials. For example, one can have against the part 11, on the side where it is not in contact with the part 12, a part in the same material as the part 12

Les figures 3, 4 et 5 représentent diverses variantes de l'enveloppe selon l'invention.Figures 3, 4 and 5 show various variants of the envelope according to the invention.

Les divers procédés de brasage exposés précédemment peuvent bien entendu être appliqués à ces variantes.The various brazing methods described above can of course be applied to these variants.

Sur la figure 3, la pièce 11 a une forme sensiblement cônique, à faible pente.In FIG. 3, the part 11 has a substantially conical shape, with a slight slope.

Le corps central se termine par une pièce 12, de forme sensiblement cônique, à faible pente. La brasure 14 est répartie entre les deux surfaces en vis-à-vis des pièces 11 et 12, sensiblement coniques, et à faible pente.The central body ends in a part 12, of substantially conical shape, with a slight slope. The solder 14 is distributed between the two surfaces facing the parts 11 and 12, which are substantially conical, and have a slight slope.

Sur la figure 4, il s'agit d'une "brasure en bout".In Figure 4, it is a "butt solder".

La pièce 11 a sensiblement la forme d'une couronne circulaire et le corps central se termine par une partie cylindrique 12 dont l'extrémité est brasée à la pièce 11.The part 11 has substantially the shape of a circular crown and the central body ends in a cylindrical part 12, the end of which is brazed to the part 11.

La figure 5 représente une autre variante de l'enveloppe selon l'invention dans laquelle ladite pièce 11 a sensiblement la forme d'une couronne circulaire.FIG. 5 represents another variant of the envelope according to the invention in which said part 11 has substantially the shape of a circular crown.

Le corps central se termine par une partie sensiblement cylindrique 12 à laquelle est soudée une autre partie sensiblement cylindrique 15 terminée par un anneau circulaire 16 brasé à ladite pièce 11.The central body ends in a substantially cylindrical part 12 to which another substantially cylindrical part 15 is welded, ending in a circular ring 16 brazed to said part 11.

Cette variante permet de réaliser le brasage sans trop modifier les pièces habituellement utilisées pour réaliser les intensificateurs.This variant allows brazing to be carried out without significantly modifying the parts usually used to make the intensifiers.

Claims (13)

1. Enveloppe sous vide pour tube intensificateur d'images radiologiques comportant une fenêtre d'entrée (10) solidaire d'un corps central (2, 3, 12) en alliage ferreux, caractérisée en ce que la fenêtre d'entrée est réalisée en un alliage d'aluminium et dE magnésium de la série 5000 et est encastrée dans une pièce en aluminium (11), de la série 1000, à laquelle elle est soudée, cette pièce étant brasée par brasure (14) à l'eutectique aluminium-silicium ou aluminium-silicium-magnésium au corps central (12).1. Vacuum envelope for radiological image intensifier tube comprising an inlet window (10) secured to a central body (2, 3, 12) made of ferrous alloy, characterized in that the inlet window is made of an alloy of aluminum and magnesium of the 5000 series and is embedded in an aluminum part (11), of the 1000 series, to which it is welded, this part being brazed by brazing (14) with aluminum eutectic. silicon or aluminum-silicon-magnesium in the central body (12). 2. Enveloppe sous vide selon la revendication 1, caractérisée en ce que la fenêtre d'entrée est réalisée en AG4MC.2. Vacuum envelope according to claim 1, characterized in that the entry window is made of AG 4 MC. 3. Enveloppe sous vide selon l'une des revendications 1 ou 2, caractérisée en ce que la pièce (11) est réalisée en aluminium de type A5.3. Vacuum envelope according to one of claims 1 or 2, characterized in that the part (11) is made of aluminum type A 5 . 4. Enveloppe sous vide selon l'une des revendications 1 à 3, caractérisée en ce que la fenêtre (10) et ladite pièce - (11) sont soudées par soudure TIG (Tungsten Inert Gaz).4. Vacuum envelope according to one of claims 1 to 3, characterized in that the window (10) and said part - (11) are welded by TIG welding (Tungsten Inert Gas). 5. Enveloppe sous vide selon l'une des revendications 1 à 4, caractérisée en ce que ladite pièce (11) a sensiblement la forme d'une couronne circulaire et en ce que le corps central se termine par une partie sensiblement cylindrique - (12), munie d'une couronne circulaire (13) qui est brasée à ladite pièce (figure 2).5. Vacuum envelope according to one of claims 1 to 4, characterized in that said part (11) has substantially the shape of a circular crown and in that the central body ends in a substantially cylindrical part - (12 ), provided with a circular crown (13) which is brazed to said part (Figure 2). 6. Enveloppe sous vide selon l'une des revendications 1 à6. Vacuum envelope according to one of claims 1 to 4, caractérisée en ce que ladite pièce (11) à une forme sensiblement cônique et en ce que le corps central est terminé par une partie sensiblement conique (12) qui est brasée à ladite pièce (figure 3).4, characterized in that said part (11) has a substantially conical shape and in that the central body is terminated by a substantially conical part (12) which is brazed to said part (Figure 3). 7. Enveloppe sous vide selon l'une des revendications 1 à 4, caractérisée en ce que ladite pièce (11) a sensiblement la forme d'une couronne circulaire et en ce que le coprs central se termine par une partie sensiblement cylindrique - (12) dont l'extrémité est brasée à ladite pièce (figure 4).7. Vacuum envelope according to one of claims 1 to 4, characterized in that said part (11) has substantially the shape of a circular crown and in that the central body ends in a substantially cylindrical part - (12 ) whose end is brazed to said part (Figure 4). 8. Enveloppe sous vide selon l'une des revendications 1 à 4, caractérisée en ce que ladite pièce (11) a sensiblement la forme d'une couronne circulaire et en ce que le corps central se termine par une partie sensiblement cylindrique - (12) à laquelle est soudée une autre partie sensiblement cylindrique (15) terminée par un anneau circulaire (16) brasé à ladite pièce (figure 5).8. Vacuum envelope according to one of claims 1 to 4, characterized in that said part (11) has substantially the shape of a circular crown and in that the central body ends in a substantially cylindrical part - (12 ) to which is welded another substantially cylindrical part (15) terminated by a circular ring (16) brazed to said part (FIG. 5). 9. Procédé de fabrication d'une enveloppe sous vide pour tube intensificateur d'images radiologiques comportant une fenêtre d'entrée (10) solidaire d'un corps central (2, 3, 12) en alliage ferreux, caractérisé en ce qu'il comporte les étapes suivantes: - on brase par brasure à l'eutectique aluminium-silicium ou aluminium-silicium-magnésium une pièce en aluminium - (11) de la série 1000 à une partie du corps central en alliage ferreux ; on encastre dans ladite pièce (11) la fenêtre d'entrée-(10) en alliage d'aluminium et de magnésium de la série 5000 ; - on soude la fenêtre (10) et ladite pièce (11) ; - on soude au reste du corps central (1, 2, 3) la partie du corps central à laquelle est brasée ladite pièce (11). 9. Method for manufacturing a vacuum envelope for an X-ray image intensifier tube comprising an inlet window (10) secured to a central body (2, 3, 12) made of ferrous alloy, characterized in that it involves the following steps: - an aluminum-aluminum or aluminum-silicon-magnesium eutectic braze is brazed an aluminum part - (11) of the 1000 series to a part of the central body of ferrous alloy; the entry window (10) made of an aluminum and magnesium alloy of the 5000 series is embedded in said part (11); - The window (10) and said part (11) are welded; - The part of the central body to which the said part (11) is brazed is welded to the rest of the central body (1, 2, 3). 10. Procédé de fabrication selon la revendication 9, caractérisé en ce que la brasure est réalisée par induction HF indirecte.10. The manufacturing method according to claim 9, characterized in that the brazing is carried out by indirect HF induction. 11. Procédé de fabrication selon l'une des revendications 9 ou 10, caractérisé en ce qu'on effectue entre la fenêtre - (10) et ladite pièce (11) une soudure TIG (Tungsten Inert Gaz).11. Manufacturing method according to one of claims 9 or 10, characterized in that one carries out between the window - ( 1 0) and said part (11) a TIG weld (Tungsten Inert Gas). 12. Procédé de fabrication selon l'une des revendications 9 à 11, caractérisé en ce qu'on usine la pièce (11) pour permettre l'encastrement de la fenêtre d'entrée (10), après avoir brasé la pièce (11) au corps central en alliage ferreux.12. Manufacturing method according to one of claims 9 to 11, characterized in that the part is machined (11) to allow the embedding of the entrance window (10), after having brazed the part (11) with a ferrous alloy central body.
EP86400055A 1985-01-15 1986-01-10 Envelope under vacuum for an x-ray image intensifier tube Expired - Lifetime EP0191664B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8500524A FR2576146B1 (en) 1985-01-15 1985-01-15 VACUUM ENVELOPE FOR RADIOLOGICAL IMAGE INTENSIFIER TUBE
FR8500524 1985-01-15

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EP0191664A1 true EP0191664A1 (en) 1986-08-20
EP0191664B1 EP0191664B1 (en) 1990-06-20

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EP (1) EP0191664B1 (en)
JP (1) JPS61168848A (en)
DE (1) DE3672173D1 (en)
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EP0563903A1 (en) * 1992-03-31 1993-10-06 Kabushiki Kaisha Toshiba X-ray image intensifier

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US5594301A (en) * 1994-06-30 1997-01-14 Hamamatsu Photonics K.K. Electron tube including aluminum seal ring
US5705885A (en) * 1994-11-25 1998-01-06 Kabushiki Kaisha Toshiba Brazing structure for X-ray image intensifier
DE19734915C1 (en) * 1997-08-12 1999-03-04 Siemens Ag X-ray image intensifier has a vacuum tight welded joint
JP3756681B2 (en) * 1997-11-21 2006-03-15 東芝電子エンジニアリング株式会社 Radiation image tube and manufacturing method thereof

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Also Published As

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FR2576146B1 (en) 1987-02-06
EP0191664B1 (en) 1990-06-20
FR2576146A1 (en) 1986-07-18
US4721884A (en) 1988-01-26
JPS61168848A (en) 1986-07-30
DE3672173D1 (en) 1990-07-26

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