EP0212712A1 - Process for manufacturing seamless hollow bodies, hollow bodies obtained by this process and apparatus used in these hollow spheres - Google Patents
Process for manufacturing seamless hollow bodies, hollow bodies obtained by this process and apparatus used in these hollow spheres Download PDFInfo
- Publication number
- EP0212712A1 EP0212712A1 EP86201286A EP86201286A EP0212712A1 EP 0212712 A1 EP0212712 A1 EP 0212712A1 EP 86201286 A EP86201286 A EP 86201286A EP 86201286 A EP86201286 A EP 86201286A EP 0212712 A1 EP0212712 A1 EP 0212712A1
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- Prior art keywords
- cores
- bath
- layer
- solvent
- hollow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D1/00—Electroforming
- C25D1/02—Tubes; Rings; Hollow bodies
Definitions
- the invention relates to a method for manufacturing hollow, closed and continuous bodies; it applies in particular to the manufacture of hollow beads composed of a continuous spheroid skin surrounding an empty internal volume.
- the invention extends to hollow bodies, in particular hollow balls, produced by implementing the method. It also relates to an installation adapted to the implementation of a preferential step of said process.
- hollow bodies having no macroscopic discontinuity on their surface; generally, the aim is to lighten the weight of a part, while allowing it to perfectly meet the requirements of the application concerned.
- These hollow beads can in particular be used to produce a modular composite material characterized essentially by its lightness and isotropic properties, easy to adapt to needs.
- Hollow balls also have an interesting application in catalysis materials because they make it possible to obtain very large specific surfaces per unit of weight.
- rolling balls hollow mechanical parts combining great lightness with appropriate mechanical strength, etc.
- a first type of known process consists in manufacturing two shells by molding or stamping and in assembling them by any known means. This process comprises several successive stages each requiring establishment operations pre- cises on workstations and its implementation is justified only in the case of high value unit parts.
- Another method which has the advantage of making it possible to precisely reproduce a given shape, consists in individually producing each hollow body by electroforming at the end of a soluble electrode around a destructible mandrel.
- this process is very expensive; moreover it leads to hollow bodies which necessarily include an extraction orifice.
- Another type of process consists in coating a core with a solid coating and then making a hole in this coating / to allow the passage of a solvent capable of dissolving said core (patent FR n ° 1 311 777, patent US No. 4,464,231).
- this process which requires individual mechanical drilling of each ball, is incompatible with bulk production and therefore has the above-mentioned defects.
- the hole made in the ball affects its homogeneity and its overall resistance.
- the present invention proposes to indicate a new method for manufacturing hollow, closed and continuous bodies.
- An object of the invention is to provide a method capable of being implemented on loose parts which therefore do not have to be positioned during the treatment phases.
- Another objective of the invention is to make it possible to obtain hollow bodies, in particular hollow balls,) each formed by a continuous skin free of any macroscopic perforation.
- Another objective is to authorize the production of hollow bodies in very diverse materials and with easily adjustable thicknesses according to the desired properties.
- Another objective is to make it possible to manufacture composite hollow bodies, that is to say the skin of which is made up of several layers which can have different properties and can be combined to meet the requirements of the application concerned.
- Another objective is to indicate a process which lends itself perfectly to the production at low cost and in very large quantity, of small hollow balls having an external diameter greater than 0.6 mm and with a skin thickness at least equal to 50 microns.
- Another objective is to allow the surface condition of the hollow bodies or hollow balls to be adapted to the applications envisaged.
- the method of the invention leads to producing each hollow body by depositing a continuous but porous coating in order to then allow the internal cores to be eliminated by dissolution through the porosities.
- cores of spherical shape are used, which have a diameter adapted to that of the balls to be obtained, generally greater than 0.5 mm.
- the method of the invention only comprises operations which can be carried out on bulk products and thus eliminates any incidental positioning operation, a factor which considerably increases costs. of implementation.
- it provides hollow bodies whose surface is continuous in its entirety without perforation or macroscopic discontinuity.
- cores are used having a plurality of small cavities opening onto the external surface of said cores, and (b) a deposit of material is produced, essentially on the surfaces outside cavities so as to obtain a coating having pores at the level of said cavities.
- a deposit of material is produced, essentially on the surfaces outside cavities so as to obtain a coating having pores at the level of said cavities.
- cores of expanded synthetic material with cells opening on their external surface.
- the cores used in the process of the invention can be produced in the form adapted by any known process, in particular in the case of beads of expanded material, by spraying drops of expandable material in a liquid. This type of process is currently well known and makes it possible to obtain spherical cores of diameters adjustable according to the conditions of implementation.
- Such a metallization process is itself known and already used to obtain metallized plastic objects (however the metallization is then carried out on a compact continuous surface and provides a compact metallic layer).
- the small cavities of the cores lead to a porous coating which allows the subsequent implementation of the dissolution phase.
- the chemical frosting operation (b l ) notably consists in immersing the loose nuclei in a dilute solvent or dilute acid, with stirring of the said nuclei inside the bath, then rinsing them off after a period of immersion corresponding to a surface attack of the nuclei. This etching changes the surface state of the core between the cavities and creates roughness which then ensures good adhesion of the thin conductive layer deposited in the following operation (b 2 ).
- chemical etching (b l ) is carried out by immersion in acetone diluted in water, in volume concentration between 50% and 90% for a period of between 600 and 5 seconds.
- the immersion time is adjusted in this range as an inverse function of the concentration in order to obtain sufficient local attacks on the surface of the nuclei, while avoiding destruction of the latter or excessively significant changes in shape.
- the metallization layer or layers deposited in phase (b 2 ) have a very small thickness, because the simple immersion technique does not in practice make it possible to obtain layers of thickness exceeding 5 microns. This or these metallization layers simply aim to make the surface of the core conductive in order to then carry out the electrodeposition ( b 3) which makes it possible to deposit layers thickness adjustable at will.
- this metallization phase (b 2 ) can be carried out by immersing the loose cores, successively in three metallization chemical baths, the first based on a tin salt in order to deposit a thin film.
- tin sensitization the second based on a silver or palladium salt in order to deposit a thin catalytic film in silver or palladium
- the third based on a copper or nickel salt in order to deposit a thin conductive layer of copper or nickel.
- the thin tin film promotes redox reactions during immersion in the second bath, but is not sufficient to provide a suitable conductivity surface.
- In the tin bath are preferably included surface-active products which promote wetting of the surface of the cores.
- the thin film of silver or palladium has a catalytic function when immersed in the third bath, but would also be insufficient to give the surface an appropriate conductivity during electroplating.
- the conductive thin layer obtained during immersion in the third bath may have a thickness of the order of 10 microns and has an electrical conductivity perfectly suited to the implementation of the electroplating operation.
- the electrolytic bath may in particular be based on nickel salt in order to obtain a crystallized layer of nickel or of nickel alloy. It can also be nickel salt base with addition of metalloid complexes (known per se) in order to obtain a layer of amorphous nickel alloy.
- a self-supporting coating is thus obtained, the thickness of which, preferably greater than 50 microns, can be adjusted by a simple adjustment of the duration of the electrodeposition operation.
- the thin conductive layer (b 2 ) essentially affects the external surface outside the cavity of the cores: consequently, the electrolytic deposition takes place only on this surface, which ensures the porous nature of the coating whatever its thickness. .
- electrodeposition it is possible to successively carry out several electrodepositions in order to obtain a multi-layer coating, the layers of which may be of different nature in order to have different properties.
- electrodeposition commonly makes it possible to deposit metals such as nickel, iron, chromium, molybdenum tungsten, cobalt and alloys of these metals, crystallized or amorphous.
- This or these electrodeposition operations may if necessary be followed by a chemical deposition of a metal layer (b 4 ) by immersion in a chemical metallization bath in order to form a thin layer on the surface; this new deposition takes place on the metal already electrodeposited, which plays a catalytic role with respect to said deposition, which makes it possible to preserve the porous nature of the coating; the new layer obtained may be advantageous in certain applications either to provide the hollow body or hollow ball with an anti-corrosion surface state (example: nickel / phosphorus, nickel / boron alloy layers, etc.), or even to increase the electrical conductivity characteristics of the hollow body (new copper layer).
- operation (c) of dissolving the cores is carried out cold or at low temperature, by bulk immersion in a solvent; it makes it possible to completely eliminate each core without modifying the skin previously formed and without causing pollution thereof or the appearance of mechanical stress in said skin.
- such dissolution makes it possible to avoid the grain magnification in crystallized alloys, and therefore retains the hardness properties of the coating; in the case of an amorphous coating; such dissolution erodes any risk of recrystallization of the material which would modify its properties.
- the internal thin films or layers which were used to carry out the electrodeposition can themselves be dissolved in a selective solvent, preserving the upper layer or layers of electrodeposition .
- This layer can be formed by using a wide variety of known methods (soaking, cathodic pulverization, vacuum evaporation, chemical vapor deposition, overmolding, etc.) and can thus be produced from a wide variety of materials ( crystallized or amorphous alloys, refractory steels, ceramics, plastics, metal oxides and their alloys, elastomers ).
- the invention extends, as a new product, to hollow bodies, in particular of spheroid shape, manufactured by implementing the method defined above, each hollow body being characterized by the presence of a closed and continuous skin, located around of an internal empty volume.
- the invention relates to a soaking installation making it possible to carry out, under good conditions, the operation (d) of soaking hollow beads, with the aim of producing a compact layer around the porous coatings after dissolution of the cores;
- the installation according to the present invention comprises a crucible containing a liquid bath of hardenable material, a rotating wheel arranged above the crucible so that its periphery passes in the vicinity of the surface of the bath, means for driving in rotation of said wheel, a chute openwork for guiding the balls having a portion located in the crucible so as to pass through the bath in the vicinity of the periphery of the wheel, means for feeding said chute into balls and means for receiving the balls ejected at the outlet of the chute .
- the installation shown diagrammatically in FIG. 1 allows the following operations to be carried out on the loose beads: (b l ) etching of the spheroid-shaped cores, (b 2 ) deposition of a tin sensitization film, deposition of a silver or palladium catalytic film and deposit of a conductive layer of copper or nickel, (c) dissolution of the nuclei.
- This installation comprises a tank 1 filled by means of a bath, suitable for the treatment to be carried out.
- This bath is circulated by a pump 2 which takes it up at the top in an overflow tank 3 and discharges it, at the bottom, into the tank.
- Pump 2 is associated with filtering means 4.
- the tank 1 contains an openwork barrel 5 which is rotatably mounted on two pivots carried by columns 6; this barrel, generally made of polypropylene with openwork meshes, carries on its periphery a toothed ring engaged with gears, themselves actuated by an electric motor.
- This speed of rotation of the barrel used in the examples being 50 revolutions / minute.
- the barrel has internally deflectors 7 which ensure agitation of the balls in the bath.
- a system of heating rods associated with thermostats allows if necessary to bring the bath up to a temperature of the order of 100 ° C.
- the installation shown diagrammatically in FIG. 2 enables one or more electroplating operations to be carried out on the loose balls (b 3 ) '.
- the anodes 8 are connected in parallel with one another on the positive terminal of a continuous supply of stabilized current, while the cathodes are connected in parallel with one another on the negative terminal of this supply.
- the speed of rotation of the barrel used in the examples being 0.6 revolutions / minute.
- FIGS. 3 and 4 makes it possible to carry out on the loose balls an additional operation (d) of depositing one or more compact layers after dissolution of the cores.
- This installation comprises a closed enclosure 10 comprising an inlet 11 through which penetrate ball supply means 12, and an outlet 13 through which the balls are ejected; means for receiving the balls (not shown) are associated with this outlet 13 outside the enclosure; these means can be constituted by a refrigerated enclosure.
- the enclosure 10 contains a crucible 14 in which is disposed a liquid bath of hardenable material to be deposited; this crucible 14 is carried by means for adjusting its height: micrometric screw 15 moving a trapezoidal shim 16 on which a crucible support 17 comes to bear.
- the crucible 14 is equipped with heating means such as electrical resistance 18 (or induction heating); a thermostatic device (not shown) makes it possible to regulate the temperature of the bath to the precise value desired.
- heating means such as electrical resistance 18 (or induction heating); a thermostatic device (not shown) makes it possible to regulate the temperature of the bath to the precise value desired.
- the crucible 14 is provided with means for regulating the level of the liquid bath; in the example, these means are constituted by a microswitch symbolized in 19 which controls the admission of material (generally in the form of powder or, if necessary in liquid form) into an inlet duct 20.
- these means for regulating level can also be constituted by any other known system and in particular by an optical system.
- the enclosure contains a rotating wheel 21 carried by a shaft 22 driven by an electric motor (not shown) at a rotation speed of 300 revolutions / minute in the examples.
- This wheel 21 is placed in a vertical plane above the crucible 14 so that its periphery passes in the vicinity of the surface of the bath without contact therewith.
- a chute 23 for guiding the balls is disposed between the supply means (conduit 12) and the crucible 14; this chute comprises an openwork portion 23a which is located in the crucible and crosses the bath in the vicinity of the periphery of the wheel 21.
- This portion 23a has the shape of a sector of a concentric circle with the wheel so as to cover in the lower part the periphery of said wheel which penetrates into the trough as far as the vicinity of the surface of the bath.
- a porthole 24 allows the interior of the enclosure to be observed.
- the balls to be coated are introduced through the conduit 12 into the chute 23; this introduction can be carried out individually by a vibrating bowl. They travel by gravity to the surface of the bath, where they are driven by the wheel 21; the latter turns them on themselves and immerses them in the bath, while driving them towards the exit.
- the hollow balls manufactured in this example are intended for the production of a modular composite material described in the patent application already mentioned filed simultaneously with the present application.
- the beads are made from spheroid cores of expanded polystyrene, as shown diagrammatically at 25 in FIG. 5a.
- the diameter of said cores is selected so as to be approximately 6 mm.
- the density of the cores is 80 Kg / m3 .
- Each core has a multitude of small cavities such as 26 opening on their external surface.
- each core has a roughness as shown diagrammatically in FIG. 5b, which allows the attachment of the first film deposited in the following phase.
- the treatment temperature is 20 ° C and. its duration of 10 seconds.
- the treatment temperature is 20 ° C and its duration 20 minutes.
- This treatment is followed by two rinses with deionized water and provides a thin conductive layer of copper.
- each core has the appearance shown in FIG. 5c: the surface outside the cavities of the cores is covered with a first very thin film of tin 27, of a second thicker silver film 28, finally with a thin layer of copper 29 of greater thickness (of the order of 10 microns).
- the beads obtained have the appearance shown diagrammatically in FIG. 5d.
- the conductive layer 29 is covered with a layer of crystallized nickel 30 with a thickness of the order of 120 microns.
- All of these layers form a coating which has open porosities at the level of the cavities 26 of the polystyrene core.
- an additional layer is deposited chemically on the nickel layer 30 in order to improve the corrosion resistance of the beads.
- This additional layer which is shown diagrammatically at 31 in FIG. 5f preserves the porous nature of the coating and can therefore be deposited before the dissolution of the cores.
- the temperature of the bath was brought to 98 ° C. and the treatment was followed by two rinses with deionized water and by drying in an oven.
- This phase consists in immersing the beads by means of the installation of FIG. 1, in a pure solvent of perchlorethylene, for 30 minutes (FIG. 5f).
- the nuclei are completely dissolved, and the beads are then dried in an oven.
- beads are obtained as shown diagrammatically 32, having a diameter of the order of 6 mm, each having a continuous skin free of macroscopic discontinuity.
- the beads have very homogeneous physicochemical characteristics, the tests having given a very low dispersion of the results.
- phase for dissolving the nuclei (c) is then carried out as in this example 1 .
- This deposition by dipping is carried out by placing in the crucible 14 a molten iron / chromium bath, of composition 75/25 at a temperature of 1520 ° C.
- the enclosure 10 is filled with a reducing atmosphere formed by nitrogen. Ball of residence time in the bath can be rated at 2/10 to 3/10 second.
- a deposit of crystallized iron / chromium alloy with a thickness of the order of 100 microns is obtained, which removes the porosity of the beads and provides them with good mechanical properties when hot.
- the beads thus obtained are then subjected to a chemical vapor deposition (CVD) of the traditional type with a view to coating them with a deposit of silicon oxide (symbolized at 34 in FIG. 6h).
- CVD chemical vapor deposition
- Such a surface deposit whose thickness is of the order of 10 microns gives with the ball an electrically insulating character and a good capacity of resistance to corrosion.
- the process of the invention makes it possible to obtain balls (and more generally hollow bodies) which are able to meet the requirements of the targeted applications: mechanical, electrical, thermal, magnetic, elastic characteristics, etc.
- the table in FIG. 7 illustrates the wide possibilities of choice that the process allows.
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Abstract
Description
L'invention concerne un procédé de fabrication de corps creux, fermés et continus ; elle s'applique en particulier pour la fabrication de billes creuses composées d'une peau sphéroide continue entourant un volume interne vide. L'invention s'étend aux corps creux, notamment billes creuses, réalisés par mise en oeuvre du procédé. Elle vise également une installation adaptée à la mise en oeuvre d'une étape préférentielle dudit procédé.The invention relates to a method for manufacturing hollow, closed and continuous bodies; it applies in particular to the manufacture of hollow beads composed of a continuous spheroid skin surrounding an empty internal volume. The invention extends to hollow bodies, in particular hollow balls, produced by implementing the method. It also relates to an installation adapted to the implementation of a preferential step of said process.
Dans de nombreux secteurs de la technique, il est nécessaire de réaliser des corps creux ne présentant aucune discontinuité macroscopique sur leur surface ; généralement, le but poursuivi est d'allèger le poids d'une pièce, tout en lui permettant de répondre parfaitement aux exigences de l'application concernée. Ces billes creuses peuvent en particulier être utilisées pour réaliser un matériau composite modulaire se caractérisant essentiellement par sa légèreté et des propriétés isotropiques, faciles à adapter aux besoins. Les billes creuses possèdent également une application intéressante dans les matériaux de catalyse car elles permettent d'obtenir des surfaces spécifiques très importantes par unité de poids. Il existe par ailleurs d'autres applications plus traditionnelles des corps creux notamment dans le secteur mécanique : billes de roulement, pièces mécaniques creuses associant une grande légèreté à une tenue mécanique appropriée ...In many fields of technology, it is necessary to produce hollow bodies having no macroscopic discontinuity on their surface; generally, the aim is to lighten the weight of a part, while allowing it to perfectly meet the requirements of the application concerned. These hollow beads can in particular be used to produce a modular composite material characterized essentially by its lightness and isotropic properties, easy to adapt to needs. Hollow balls also have an interesting application in catalysis materials because they make it possible to obtain very large specific surfaces per unit of weight. There are also other more traditional applications of hollow bodies, particularly in the mechanical sector: rolling balls, hollow mechanical parts combining great lightness with appropriate mechanical strength, etc.
On connait actuellement plusieurs types de procédés permettant de fabriquer des corps creux,-et en particulier des billes creuses. Dans tous ces procédés, les corps creux sont fabriqués en série et subissent des opérations de fabrication individuelle, qui exigent un positionnement précis de chaque pièce ; en conséquence ces procédés sont généralement onéreux et leur automatisation conduit à des équipements complexes et chers.Several types of process are currently known for making hollow bodies, and in particular hollow balls. In all these processes, the hollow bodies are produced in series and undergo individual manufacturing operations, which require precise positioning of each part; consequently these methods are generally expensive and their automation leads to complex and expensive equipment.
Un premier type de procédé connu consiste à fabriquer deux coquilles par moulage ou emboutissage et à les assembler par tout moyen connu. Ce procédé comporte plusieurs étapes successives exigeant chacune des opérations de mise en place pré- cises sur des postes de travail et sa mise en oeuvre n'est justifiée que dans le cas de pièces unitaires de valeur élevée.A first type of known process consists in manufacturing two shells by molding or stamping and in assembling them by any known means. This process comprises several successive stages each requiring establishment operations pre- cises on workstations and its implementation is justified only in the case of high value unit parts.
Un autre type de procédé, qui est notamment utilisé pour réaliser de petites billes de chaînettes, consiste à emboutir celles-ci à partir d'un tube ; ce procédé, beaucoup moins onéreux, présente toutefois plusieurs inconvénients : en premier lieu, il ne permet pas d'obtenir une surface de bille continue, puisque chaque bille se trouve nécessairement perforée à deux endroits ; de plus, la technique d'emboutissage utilisée ne permet de fabriquer des billes que dans une faible plage d'épaisseur et avec un choix de matériaux très limités (matériaux aptes à subir un fluage sans formation de criques).Another type of process, which is used in particular for making small chain beads, consists in stamping them from a tube; this process, which is much less expensive, however has several drawbacks: firstly, it does not make it possible to obtain a continuous ball surface, since each ball is necessarily perforated in two places; in addition, the stamping technique used only allows the production of balls in a small thickness range and with a choice of very limited materials (materials capable of undergoing creep without the formation of cracks).
Un autre procédé, qui présente l'avantage de permettre de reproduire de façon précise une forme donnée, consiste à réaliser individuellement chaque corps creux par électroformage en bout d'une électrode soluble autour d'un mandrin destructible. Toutefois de par sa nature même, ce procédé est très onéreux ; de plus il conduit à des corps creux qui comportent nécessairement un orifice d'extraction.Another method, which has the advantage of making it possible to precisely reproduce a given shape, consists in individually producing each hollow body by electroforming at the end of a soluble electrode around a destructible mandrel. However, by its very nature, this process is very expensive; moreover it leads to hollow bodies which necessarily include an extraction orifice.
Un autre type de procédé consiste à revêtir un noyau d'un revêtement solide et à pratiquer ensuite un trou dans ce re- vêtement/pour permettre le passage d'un solvant capable de dissoudre ledit noyau (brevet FR n° 1 311 777, brevet US n° 4 464 231). Toutefois, ce procédé qui exige un perçage mécanique individuel de chaque bille est incompatible avec une fabrication en vrac et possède donc les défauts sus-évoqués. De plus, le trou pratiqué dans la bille affecte l'homogénéité de celle-ci et sa résistance d'ensemble.Another type of process consists in coating a core with a solid coating and then making a hole in this coating / to allow the passage of a solvent capable of dissolving said core (patent FR n ° 1 311 777, patent US No. 4,464,231). However, this process, which requires individual mechanical drilling of each ball, is incompatible with bulk production and therefore has the above-mentioned defects. In addition, the hole made in the ball affects its homogeneity and its overall resistance.
Pour mémoire, il convient également de citer le très ancien procédé de souffage de verre, qui est toutefois limité à ce matériau et conduit à des difficultés pour maitriser la forma du corps creux réalisé.For the record, it is also worth mentioning the very old glass blowing process, which is however limited to this material and leads to difficulties in mastering the form of the hollow body produced.
La présente invention se propose d'indiquer un nouveau procédé de fabrication de corps creux, fermés et continus.The present invention proposes to indicate a new method for manufacturing hollow, closed and continuous bodies.
Un objectif de l'invention est de fournir un procédé apte à être mis en oeuvre sur des pièces en vrac qui n'ont donc pas à être positionnées au cours des phases de traitement.An object of the invention is to provide a method capable of being implemented on loose parts which therefore do not have to be positioned during the treatment phases.
Un autre objectif de l'invention est de permettre d'obtenir des corps creux, notamment des billes creuses, ) formés chacun par une peau continue exempte de toute perforation macroscopique.Another objective of the invention is to make it possible to obtain hollow bodies, in particular hollow balls,) each formed by a continuous skin free of any macroscopic perforation.
Un autre objectif est d'autoriser la fabrication de corps creux en des matériaux très divers et avec des épaisseurs facilement ajustables en fonction des propriétés recherchées.Another objective is to authorize the production of hollow bodies in very diverse materials and with easily adjustable thicknesses according to the desired properties.
Un autre objectif est de permettre de fabriquer des corps creux composites, c'est-à-dire dont la peau est constituée de plusieurs couches qui peuvent présenter des propriétés différentes et se combiner pour satisfaire les exigences de l'application concernée.Another objective is to make it possible to manufacture composite hollow bodies, that is to say the skin of which is made up of several layers which can have different properties and can be combined to meet the requirements of the application concerned.
Un autre objectif est d'indiquer un procédé se prêtant parfaitement à la fabrication à coût réduit et en très grande quantité, de petites billes creuses ayant un diamètre externe supérieur à 0,6 mm et d'une épaisseur de peau au moins égale à 50 microns.Another objective is to indicate a process which lends itself perfectly to the production at low cost and in very large quantity, of small hollow balls having an external diameter greater than 0.6 mm and with a skin thickness at least equal to 50 microns.
Un autre objectif est de permettre d'adapter l'état de surface des corps creux ou billes creuses aux applications envisagées.Another objective is to allow the surface condition of the hollow bodies or hollow balls to be adapted to the applications envisaged.
Le procédé conforme à l'invention pour la fabrication de corps creux fermés et continus consiste :
- (a) à utiliser des noyaux en une matière soluble dans un solvant, de forme correspondant au volume interne vide des corps creux à fabriquer,
- (b) à déposer sur chaque noyau soluble un revêtement poreux, ayant une tenue mécanique propre à le rendre autoporteur et une porosité ouverte apte à permettre le passage du solvant,
- (c) à disposer les noyaux ainsi revêtus dans le solvant jusqu'à dissolution desdits noyaux.
- (a) using cores of a material soluble in a solvent, of a shape corresponding to the empty internal volume of the hollow bodies to be manufactured,
- (b) depositing on each soluble core a porous coating, having a mechanical strength suitable for making it self-supporting and an open porosity capable of allowing the passage of the solvent,
- (c) disposing the cores thus coated in the solvent until the dissolution of said cores.
Ainsi, le procédé de l'invention conduit à réaliser chaque corps creux par dépôt d'un revêtement continu mais poreux afin de permettre d'éliminer ensuite les noyaux internes par dissolution à travers les porosités. Dans le cas de bille creuses, l'on utilise des noyaux de forme sphérofde, qui ont un diamètre adapté à celui des billes à obtenir, généralement supérieur à 0,5 mm. Le procédé de l'invention ne comprend que des opérations exécutables sur des produits en vrac et supprime ainsi toute opération accessoire de positionnement, facteur d'accroissement considérable des coûts de mise en oeuvre. En outre il fournit des corps creux dont la surface est continue dans sa totalité sans perforation ni discontinuité macroscopique.Thus, the method of the invention leads to producing each hollow body by depositing a continuous but porous coating in order to then allow the internal cores to be eliminated by dissolution through the porosities. In the case of hollow balls, cores of spherical shape are used, which have a diameter adapted to that of the balls to be obtained, generally greater than 0.5 mm. The method of the invention only comprises operations which can be carried out on bulk products and thus eliminates any incidental positioning operation, a factor which considerably increases costs. of implementation. In addition, it provides hollow bodies whose surface is continuous in its entirety without perforation or macroscopic discontinuity.
Selon une caractéristique préférentielle de l'invention, (a) l'on utilise des noyaux présentant une pluralité de petites cavités s'ouvrant sur la surface externe desdits noyaux, et (b) l'on réalise un dépôt de matière, essentiellement sur les surfaces hors cavités de façon à obtenir un revêtement présentant des pores au niveau desdites cavités. Par exemple, on peut utiliser des noyaux en matière synthétique expansée à cellules s'ouvrant sur leur surface externe.According to a preferred characteristic of the invention, (a) cores are used having a plurality of small cavities opening onto the external surface of said cores, and (b) a deposit of material is produced, essentially on the surfaces outside cavities so as to obtain a coating having pores at the level of said cavities. For example, it is possible to use cores of expanded synthetic material with cells opening on their external surface.
L'on obtient ainsi, après dépôt, un revêtement poreux dont les pores sont conditionnés par le taux d'expansion de la matière synthétique utilisée. Ce taux d'expansion est choisi pour conférer au revêtement une porosité permettant ensuite une pénétration correcte du solvant afin d'obtenir la dissolution des noyaux.This gives a porous coating after deposition, the pores of which are conditioned by the rate of expansion of the synthetic material used. This expansion rate is chosen to give the coating porosity allowing correct penetration of the solvent in order to obtain the dissolution of the cores.
L'on peut en particulier utiliser des noyaux en polystyrène expansé, dont la dissolution peut être réalisée par immersion dans un solvant du groupe : acétone, benzène, perchloréthylène, trichlorétylène, éther.One can in particular use expanded polystyrene cores, the dissolution of which can be carried out by immersion in a solvent of the group: acetone, benzene, perchlorethylene, trichlorethylene, ether.
Les noyaux utilisés dans le procédé de l'invention peuvent être réalisés à la forme adaptée par tout procédé connu, en particulier dans le cas de billes de matière expansée, par pulvérisation de gouttes de matière expansable dans un liquide. Ce type de procédé est à l'heure actuelle bien connu et permet d'obtenir des noyaux sphériques de diamètres ajustables en fonction des conditions de mise en oeuvre.The cores used in the process of the invention can be produced in the form adapted by any known process, in particular in the case of beads of expanded material, by spraying drops of expandable material in a liquid. This type of process is currently well known and makes it possible to obtain spherical cores of diameters adjustable according to the conditions of implementation.
Par ailleurs selon un mode de mise en oeuvre avantageux du procédé de l'invention, le dépôt du revêtement poreux sur chacun des noyaux consiste :
- (bl) à effectuer un dépolissage desdits noyaux de façon à créer sur leur surface hors cavités une rugosité propre à permettre une adhérence mécanique de ladite surface vis-à-vis des métaux,
- (b2) à immerger ensuite les noyaux dans au moins un bain chimique de métallisation en vue de déposer au moins une couche mince conductrice sur lesdits noyaux,
- (b3) à immerger les noyaux ainsi traités dans au moins un bain électrolytique en vue de réaliser une électrodéposition d'au moins une couche métallique sur la ou les couches minces conductrices précitées.
- (b l ) performing a roughening of said cores so as to create on their surface outside cavities a roughness suitable for allowing mechanical adhesion of said surface with respect to metals,
- (b 2 ) then immersing the cores in at least one metallization chemical bath in order to deposit at at least one thin conductive layer on said cores,
- (b 3 ) immersing the cores thus treated in at least one electrolytic bath in order to carry out an electrodeposition of at least one metal layer on the aforementioned thin conductive layer (s).
Un tel procédé de métallisation est en lui- même connu et déjà utilisé pour obtenir des objets en matière synthétique métallisée (toutefois la métallisation s'effectue alors sur une surface continue compacte et fournit une couche métallique compacte). Dans le cas de l'invention, les petites cavités des noyaux conduisent à un revêtement poreux qui permet la mise en oeuvre ultérieure de la phase de dissolution.Such a metallization process is itself known and already used to obtain metallized plastic objects (however the metallization is then carried out on a compact continuous surface and provides a compact metallic layer). In the case of the invention, the small cavities of the cores lead to a porous coating which allows the subsequent implementation of the dissolution phase.
L'opération (bl) de dépolissage chimique consiste notamment à immerger les noyaux en vrac dans un solvant dilué ou un acide dilué, avec agitation desdits noyaux à l'intérieur du bain, puis à les rincer au terme d'une durée d'immersion correspondant à une attaque superficielle des noyaux. Ce dépolissage modifie l'état de surface du noyau entre les cavités et crée des aspérités qui assurent ensuite une bonne adhérence de la couche mince conductrice déposée dans l'opération suivante (b2).The chemical frosting operation (b l ) notably consists in immersing the loose nuclei in a dilute solvent or dilute acid, with stirring of the said nuclei inside the bath, then rinsing them off after a period of immersion corresponding to a surface attack of the nuclei. This etching changes the surface state of the core between the cavities and creates roughness which then ensures good adhesion of the thin conductive layer deposited in the following operation (b 2 ).
Par exemple, dans le cas de noyaux en polystyrène expansé, le dépolissage chimique (bl) est effectué par immersion dans de l'acétone dilué dans de l'eau, en concentration volumique comprise entre 50 % et 90 % pendant une durée comprise entre 600 et 5 secondes. La durée d'immersion est réglée dans cette plage en fonction inverse de la concentration afin d'obtenir des attaques locales suffisantes de la surface des noyaux, tout en évitant la destruction de ceux-ci ou des modifications de forme trop importantes.For example, in the case of expanded polystyrene cores, chemical etching (b l ) is carried out by immersion in acetone diluted in water, in volume concentration between 50% and 90% for a period of between 600 and 5 seconds. The immersion time is adjusted in this range as an inverse function of the concentration in order to obtain sufficient local attacks on the surface of the nuclei, while avoiding destruction of the latter or excessively significant changes in shape.
La ou les couches de métallisation déposées à la phase (b2) ont une épaisseur très faible, car la technique de simple immersion ne permet pas en pratique d'obtenir des couches d'épaisseur dépassant 5 microns. Cette ou ces couches de métallisation visent simplement à rendre la surface du noyau conductrice afin de réaliser ensuite l'électrodéposition (b3) qui permet de déposer des couches d'épaisseur ajustables à volonté.The metallization layer or layers deposited in phase (b 2 ) have a very small thickness, because the simple immersion technique does not in practice make it possible to obtain layers of thickness exceeding 5 microns. This or these metallization layers simply aim to make the surface of the core conductive in order to then carry out the electrodeposition ( b 3) which makes it possible to deposit layers thickness adjustable at will.
De façon connue en soi, cette phase de métallisation (b2) peut être réalisée en immergeant les noyaux en vrac, successivement dans trois bains chimiques de métallisation, le premier à base d'un sel d'étain en vue de déposer une fine pellicule de sensibilisation en étain, le deuxième à base d'un sel d'argent ou de palladium en vue de déposer une fine pellicule catalytique en argent ou palladium, le troisième à base d'un sel de cuivre ou de nickel en vue de déposer une couche mince conductrice en cuivre ou en nickel. La fine pellicule d'étain favorise les réactions d'oxydoréduction lors de l'immersion dans le deuxième bain, mais n'est pas suffisante pour fournir une surface de conductibilité appropriée. Dans le bain d'étain sont de préférence inclus des produits tensio-actifs qui favorisent le mouillage de la surface des noyaux. La fine pellicule d'argent ou de palladium possède une fonction de catalyseur lors de l'immersion dans le troisième bain, mais serait également insuffisante pour conférer à la surface une conductibilité appropriée lors de l'électrodéposition.In a manner known per se, this metallization phase (b 2 ) can be carried out by immersing the loose cores, successively in three metallization chemical baths, the first based on a tin salt in order to deposit a thin film. tin sensitization, the second based on a silver or palladium salt in order to deposit a thin catalytic film in silver or palladium, the third based on a copper or nickel salt in order to deposit a thin conductive layer of copper or nickel. The thin tin film promotes redox reactions during immersion in the second bath, but is not sufficient to provide a suitable conductivity surface. In the tin bath are preferably included surface-active products which promote wetting of the surface of the cores. The thin film of silver or palladium has a catalytic function when immersed in the third bath, but would also be insufficient to give the surface an appropriate conductivity during electroplating.
La couche mince conductrice obtenue lors de l'immersion dans le troisième bain peut posséder une épaisseur de l'ordre de 10 microns et présente une conductibilité électrique parfaitement adaptée à la mise en oeuvre de l'opération d'électrodéposition.The conductive thin layer obtained during immersion in the third bath may have a thickness of the order of 10 microns and has an electrical conductivity perfectly suited to the implementation of the electroplating operation.
Cette électrodéposition (b3) consiste de préférence :
- . à disposer les noyaux en vrac dans un tonneau rotatif ajouré, possédant des cathodes en partie haute,
- . à immerger ledit tonneau dans un bain électrolytique à base d'un sel métallique, contenant des anodes plongées dans ledit bain en regard du tonneau,
- . et à appliquer une différence de potentiel entre anodes et cathodes pendant une durée fonction de l'épaisseur de la couche métallique désirée.
- . placing the cores in bulk in an openwork rotating barrel having cathodes in the upper part,
- . immersing said barrel in an electrolytic bath based on a metal salt, containing anodes immersed in said bath opposite the barrel,
- . and applying a potential difference between anodes and cathodes for a period depending on the thickness of the desired metal layer.
Le bain électrolytique peut notamment être à base de sel de nickel en vue d'obtenir une couche cristallisée de nickel ou d'alliage de nickel. Il peut également être à base de sel de nickel avec addition de complexes métalloidiques (connus en soi) en vue d'obtenir une couche d'alliage de nickel amorphe.The electrolytic bath may in particular be based on nickel salt in order to obtain a crystallized layer of nickel or of nickel alloy. It can also be nickel salt base with addition of metalloid complexes (known per se) in order to obtain a layer of amorphous nickel alloy.
On obtient ainsi un revêtement autoporteur dont l'épaisseur, de préférence supérieure à 50 microns, peut être ajustée par un simple réglage de la durée de l'opération d'électrodéposition. Il est à noter que la couche mince conductrice (b2) affecte essentiellement la surface externe hors cavité des noyaux : en conséquence, le dépôt électrolytique s'effectue uniquement sur cette surface, ce qui assure le caractère poreux du revêtement quelle que soit son épaisseur.A self-supporting coating is thus obtained, the thickness of which, preferably greater than 50 microns, can be adjusted by a simple adjustment of the duration of the electrodeposition operation. It should be noted that the thin conductive layer (b 2 ) essentially affects the external surface outside the cavity of the cores: consequently, the electrolytic deposition takes place only on this surface, which ensures the porous nature of the coating whatever its thickness. .
Il est possible de réaliser successivement plusieurs électrodépositions en vue d'obtenir un revêtement multi-couches, dont les couches peuvent être de nature différente afin de présenter des propriétés différentes. l'électrodéposition permet de façon courante de déposer des métaux tels que nickel, fer, chrome, molybdène tungstène, cobalt et alliages de ces métaux, cristallisés ou amorphes.It is possible to successively carry out several electrodepositions in order to obtain a multi-layer coating, the layers of which may be of different nature in order to have different properties. electrodeposition commonly makes it possible to deposit metals such as nickel, iron, chromium, molybdenum tungsten, cobalt and alloys of these metals, crystallized or amorphous.
Cette ou ces opérations d'électrodéposition peuvent le cas échéant être suivies d'un dépôt chimique d'une couche métallique (b4) par immersion dans un bain chimique de métallisation en vue de former en surface une couche mince ; ce nouveau dépôt s'effectue sur le métal déjà électrodéposé, lequel joue un rôle de catalyseur à l'égard dudit dépôt, ce qui permet de préserver le caractère poreux du revêtement ; la nouvelle couche obtenue peut être intéressante dans certaines applications soit pour fournir au corps creux ou bille creuse un état de surface anti-corrosif (exemple : couches en alliage nickel/phosphore, nickel/bore,...), soit encore pour accroître les caractéristiques de conductibilité électriques du corps creux (nouvelle couche en cuivre).This or these electrodeposition operations may if necessary be followed by a chemical deposition of a metal layer (b 4 ) by immersion in a chemical metallization bath in order to form a thin layer on the surface; this new deposition takes place on the metal already electrodeposited, which plays a catalytic role with respect to said deposition, which makes it possible to preserve the porous nature of the coating; the new layer obtained may be advantageous in certain applications either to provide the hollow body or hollow ball with an anti-corrosion surface state (example: nickel / phosphorus, nickel / boron alloy layers, etc.), or even to increase the electrical conductivity characteristics of the hollow body (new copper layer).
Par ailleurs, l'opération (c) de dissolution des noyaux est réalisée à froid ou à faible température, par immersion en vrac dans un solvant ; elle permet d'éliminer totalement chaque noyau sans modifier la peau précédemment formée et sans engendrer une pollution de celle-ci ou l'apparition de contrainte mécanique dans ladite peau. En particulier, une telle dissolution permet d'éviter le grossissement des grains dans les alliages cristallisés, et en conséquence, conserve les propriétés de dureté du revêtement ; dans le cas d'un revêtement amorphe ; une telle dissolution écate tout risque de recristallisation de la matière qui en modifierait les propriétés.Furthermore, operation (c) of dissolving the cores is carried out cold or at low temperature, by bulk immersion in a solvent; it makes it possible to completely eliminate each core without modifying the skin previously formed and without causing pollution thereof or the appearance of mechanical stress in said skin. In particular, such dissolution makes it possible to avoid the grain magnification in crystallized alloys, and therefore retains the hardness properties of the coating; in the case of an amorphous coating; such dissolution erodes any risk of recrystallization of the material which would modify its properties.
Le cas échéant, les pellicules ou couches minces internes qui ont servi à effectuer l'électrodéposition (pellicule de sensibilisation, pellicule catalytique et couche mince conductrice) peuvent être elles-mêmes dissoutes dans un solvant sélectif, préservant la ou les couches supérieures d'électrodéposition.If necessary, the internal thin films or layers which were used to carry out the electrodeposition (sensitization film, catalytic film and thin conductive layer) can themselves be dissolved in a selective solvent, preserving the upper layer or layers of electrodeposition .
Par ailleurs, après dissolution des noyaux, (et eventuellement des pellicules ou couches internes), il est possible (d) de réaliser sur le revêtement poreux le dépôt d'une couche compacte pour éliminer le caractère poreux de l'objet ou pour l'habiller d'un matériau différent adapté à l'application. Cette couche peut être formée par mise en oeuvre d'une grande diversité des procédés connus (trempage, pulvériqation cathodique, évaporation sous vide, dépôt chimique en phase vapeur, surmoulage...) et peut ainsi être réalisée en une grande diversité de matériaux (alliages cristallisés ou amorphes, aciers réfractaires, céramiques, matières synthétiques, oxydes métalliques et leurs alliages, élastomères...)Furthermore, after dissolution of the cores (and possibly of the films or internal layers), it is possible (d) to deposit on the porous coating the deposition of a compact layer to eliminate the porous nature of the object or for the cover with a different material suitable for the application. This layer can be formed by using a wide variety of known methods (soaking, cathodic pulverization, vacuum evaporation, chemical vapor deposition, overmolding, etc.) and can thus be produced from a wide variety of materials ( crystallized or amorphous alloys, refractory steels, ceramics, plastics, metal oxides and their alloys, elastomers ...)
L'invention s'étend, en tant que produit nouveau, aux corps creux, notamment de forme sphéroïde, fabriqués par mise en oeuvre du procédé défini précédemment, chaque corps creux se caractérisant par la présence d'une peau fermée et continue, située autour d'un volume vide interne.The invention extends, as a new product, to hollow bodies, in particular of spheroid shape, manufactured by implementing the method defined above, each hollow body being characterized by the presence of a closed and continuous skin, located around of an internal empty volume.
Par ailleurs, l'invention vise une installation de trempage permettant de mettre en oeuvre dans de bonnes conditions, l'opération (d) de trempage de billes creuses, dans le but de réaliser une couche compacte autour des revêtements poreux après dissolution des noyaux ; l'installation conforme à la présente invention comprend un creuset contenant un bain liquide de matière durcissable, une roue tournante disposée au-dessus du creuset de façon que son pourtour passe au voisinage de la surface du bain, des moyens d'entraînement en rotation de ladite roue, une goulotte ajourée de guidage des billes ayant une portion située dans le creuset de façon à traverser le bain au voisinage du pourtour de la roue, des moyens d'alimentation de ladite goulotte en billes et des moyens de réception des billes éjectées à la sortie de la goulotte.Furthermore, the invention relates to a soaking installation making it possible to carry out, under good conditions, the operation (d) of soaking hollow beads, with the aim of producing a compact layer around the porous coatings after dissolution of the cores; the installation according to the present invention comprises a crucible containing a liquid bath of hardenable material, a rotating wheel arranged above the crucible so that its periphery passes in the vicinity of the surface of the bath, means for driving in rotation of said wheel, a chute openwork for guiding the balls having a portion located in the crucible so as to pass through the bath in the vicinity of the periphery of the wheel, means for feeding said chute into balls and means for receiving the balls ejected at the outlet of the chute .
D'autres caractéristiques et avantages de l'invention se dégageront de la description qui suit en référence aux dessins annexées, lesquels d'une part présentent des schémas des appareillages utilisés, d'autre part illustrent les étapes du procédé mis en oeuvre aux exemples 1 et 2 dans le cas de la fabrication de billes creuses, enfin, fournissent un tableau donnant la nature des dépôts susceptibles d'être obtenus avec les techniques correspondantes ; sur ces dessins :
- - les figures 1
et 2 sont des coupes schématiques d'une installation classique permettant la mise en oeuvre de phases du procédé, - - les figures 3
et 4 sont des coupes, respectivement par un plan vertical A A' et par un plan vertical perpendiculaire B B', d'une installation de mise en oeuvre d'une phase préférentielle du procédé, - - les figures 5a, 5b, 5c, 5d, 5e, 5f et 5g sont des schémas illustrant le procédé de l'invention (exemple 1) et les figures 6a et 6b sont des schémas concernant l'exemple 2,
- - enfin la figure 7 est un tableau des natures de corps creux susceptibles d'être obtenus.
- FIGS. 1 and 2 are schematic sections of a conventional installation allowing the implementation of phases of the process,
- FIGS. 3 and 4 are sections, respectively through a vertical plane AA 'and through a perpendicular vertical plane B B', of an installation for implementing a preferential phase of the process,
- FIGS. 5a, 5b, 5c, 5d, 5e, 5f and 5g are diagrams illustrating the process of the invention (example 1) and FIGS. 6a and 6b are diagrams concerning example 2,
- - Finally, Figure 7 is a table of the types of hollow body that can be obtained.
L'installation schématisée à la figure 1 permet d'effectuer sur les billes en vrac les opérations suivantes : (bl) dépolissage des noyaux de forme sphéroïde, (b2) dépôt d'une pellicule de sensibilisation en étain, dépôt d'une péllicule catalytique en argent ou palladium et dépôt d'une couche conductrice en cuivre ou nickel, (c) dissolution des noyaux.The installation shown diagrammatically in FIG. 1 allows the following operations to be carried out on the loose beads: (b l ) etching of the spheroid-shaped cores, (b 2 ) deposition of a tin sensitization film, deposition of a silver or palladium catalytic film and deposit of a conductive layer of copper or nickel, (c) dissolution of the nuclei.
Cette installation comprend une cuve 1 remplie au moyen d'un bain, adapté au traitement à réaliser. Ce bain est mis en circulation par une pompe 2 qui le préléve en partie haute dans un bac de surverse 3 et le refoule, en partie basse, dans la cuve. La pompe 2 est associée à des moyens de filtrage 4.This installation comprises a
La cuve 1 contient un tonneau ajouré 5 qui est monté tournant sur deux pivots portés par des colonnes 6 ; ce tonneau généralement en polypropylène à mailles ajourées, porte sur sa périphérie une couronne dentée en prise avec des engrenages, eux-mêmes actionnés par un moteur électrique. La vitesse de rotation du tonneau mis en oeuvre dans les exemples étant de 50 tours/minute.The
Le tonneau comporte intérieurement des déflecteurs 7 qui assurent une agitation des billes dans le bain.The barrel has internally deflectors 7 which ensure agitation of the balls in the bath.
Un système de cannes chauffantes associés à des thermostats permet le cas échéant de porter le bain jusqu'à une température de l'ordre de 100° C.A system of heating rods associated with thermostats allows if necessary to bring the bath up to a temperature of the order of 100 ° C.
L'installation schématisée à la figure 2 permet d'effectuer sur les billes en vrac une ou des opérations d'électrodéposition (b3)' The installation shown diagrammatically in FIG. 2 enables one or more electroplating operations to be carried out on the loose balls (b 3 ) '.
Cette installation est analogue à la précédente mais comprend en outre :
- . une série d'anodes telles que 8 formées par des plaques du métal à déposer, situées en regard du tonneau de chaque coté de celui-ci,
- . une série de cathodes telles que 9 formées par des boules pleines en acier inoxydablessituées le long du tonneau, en partie haute de celui-ci avec un décalage dans le sens de la rotation.
- . a series of anodes such as 8 formed by plates of the metal to be deposited, located opposite the barrel on each side thereof,
- . a series of cathodes such as 9 formed by solid stainless steel balls located along the barrel, in the upper part thereof with an offset in the direction of rotation.
Les anodes 8 sont reliées en parallèle les unes des autres sur la borne positive d'une alimentation continue en courant stabilisé, cependant que les cathodes sont reliées en parallèle les unes des autres sur la borne négative de cette alimentation.The
La vitesse de rotation du tonneau mise en oeuvre dans les exemples étant de 0,6 tours/minute.The speed of rotation of the barrel used in the examples being 0.6 revolutions / minute.
Par ailleurs l'installation représentée au figures 3 et 4 permet d'effectuer sur les billes en vrac une opération complémentaire (d) de dépôt d'une ou de plusieurs couches compactes après dissolution des noyaux.Furthermore, the installation shown in FIGS. 3 and 4 makes it possible to carry out on the loose balls an additional operation (d) of depositing one or more compact layers after dissolution of the cores.
Cette installation comprend une enceinte fermée 10 comportant une entrée 11 par laquelle pénétrent des moyens d'alimentation en billes 12, et une sortie 13 par laquelle sont éjectées les billes ; des moyens de réception des billes (non représentés) sont associés à cette sortie 13 à l'extérieur de l'enceinte ; ces moyens peuvent être constitués par une enceinte réfrigérée.This installation comprises a
L'enceinte 10 contient un creuset 14 dans lequel est disposé un bain liquide de matière durcissable à déposer ; ce creuset 14 est porté par des moyens de réglage de sa hauteur : vis micrométrique 15 déplaçant une cale trapézoldale 16 sur laquelle vient en appui un support de creuset 17.The
Le creuset 14 est équipé de moyens de chauffage tels que résistance électrique 18 (ou chauffage à induction) ; un dispositif thermostatique (non représenté) permet de réguler la température du bain à la valeur précise souhaitée.The
De plus le creuset 14 est doté de moyens de régulation du niveau du bain liquide ; en l'exemple, ces moyens sont constitués par un microcontact symbolisé en 19 qui commande l'admission de matière (généralement sous forme de poudre ou, le cas échéant sous forme liquide) dans un conduit d'arrivée 20. Ces moyens de régulation de niveau peuvent également être constitués par tout autre système connu et en particulier par un système optique.In addition, the
L'enceinte contient une roue tournante 21 portée par un arbre 22 entraîné par un moteur électrique (non représenté) à une vitesse de rotation de 300 tours/minute dans les exemples. Cette roue 21 est placée dans un plan vertical au-dessus du creuset 14 de façon que son pourtour passe au voisinage de la surface du bain sans contact avec celle-ci.The enclosure contains a
Une goulotte 23 de guidage des billes est disposée entre les moyens d'alimentation (conduit 12) et le creuset 14 ; cette goulotte comprend une portion ajourée 23a qui est située dans le creuset et traverse le bain au voisinage du pourtour de la roue 21.A
Cette portion 23a présente la forme d'un secteur de cercle concentrique avec la roue de façon à coiffer en partie basse le pourtour de ladite roue laquelle pénétre dans la goulotte jusqu'au voisinage de la surface du bain.This
Un hublot 24 permet d'observer l'intérieur de l'enceinte.A
Les billes à revêtir sont introduites par le conduit 12 dans la goulotte 23 ; cette introduction peut être réalisée à l'unité par un bol vibrant. Elles cheminent par gravité jusqu'à la surface du bain, où elles sont entraînées par la roue 21 ; cette dernière les fait tourner sur elles-mêmes et les immerge dans le bain, tout en les entraînant vers la sortie.The balls to be coated are introduced through the
Les expérimentations ont montré qu'une telle installation permet d'obtenir des revêtements homogènes sur chaque bille en raison :
- . d'un temps de séjour dans le bain remarquablement constant pour toutes les billes,
- . d'une mise en contact uniforme de toute la surface des billes avec le bain (par l'effet des mouvements auxquels elles sont soumises),
- . de la suppression de tout risque de collage entre billes.
- . a remarkably constant residence time in the bath for all the beads,
- . uniform contact of the entire surface of the balls with the bath (by the effect of the movements to which they are subjected),
- . the elimination of any risk of sticking between balls.
A la sortie du bain, les billes sont ejectées vers la sortie 13 et refroidies dans le cas d'un dépôt à chaud.On leaving the bath, the balls are ejected towards
Les deux exemples qui suivent illustrent les étapes du procédé de l'invention et ont été mis en oeuvre au moyen des installations ci-dessus décrites.The two examples which follow illustrate the stages of the process of the invention and have been implemented by means of the installations described above.
Les billes creuses fabriquées à cet exemple sont destinées à la réalisation d'un matériau composite modulaire décrit dans la demande de brevet déjà évoquée déposée simultanément avec la présente demande.The hollow balls manufactured in this example are intended for the production of a modular composite material described in the patent application already mentioned filed simultaneously with the present application.
Les billes sont fabriquées à partir de noyaux sphérofdes en polystyrène expansé, tels que schématisés en 25 à la figure 5a. Le diamètre desdits noyaux est sélectionné de façon à être d'environ 6 mm. La densité des noyaux est de 80 Kg/m3. The beads are made from spheroid cores of expanded polystyrene, as shown diagrammatically at 25 in FIG. 5a. The diameter of said cores is selected so as to be approximately 6 mm. The density of the cores is 80 Kg / m3 .
Chaque noyau comporte une multitude de petites cavités telles que 26 s'ouvrant sur leur surface externe.Each core has a multitude of small cavities such as 26 opening on their external surface.
La fabrication de ces noyaux est bien connue en elle-même et ceux-ci proviennent en l'exemple de la société "TOULPAC (Toulouse)".The manufacture of these cores is well known in itself and these come in the example of the company "TOULPAC (Toulouse)".
La première phase du traitement consiste à dépolir les noyaux par immersion dans un solvant de composition suivante en volume :
- - acétone 90 %
- - eau désionisée 10 S
- - acetone 90%
- - deionized water 10 S
Cette immersion a été effectuée dans l'installation représentée à la figure 1 pendant une durée de 5 minutes à la température ambiante de 20° C.This immersion was carried out in the installation shown in Figure 1 for a period of 5 minutes at room temperature of 20 ° C.
Deux rinçages successifs sont ensuite effectués dans la même installation avec une eau désionisée pendant des durées de l'ordre de 2 mn chacun.Two successive rinses are then carried out in the same installation with deionized water for periods of the order of 2 min each.
A la suite de ce dépolissage la surface externe de chaque noyau présente une rugosité telle que schématisée à la figure 5b, qui permet l'accrochage de la première péllicule déposée à la phase suivante.Following this etching, the external surface of each core has a roughness as shown diagrammatically in FIG. 5b, which allows the attachment of the first film deposited in the following phase.
Cette phase s'effectue en trois étapes successives dans les conditions suivantes (installation de la figure 1) :
- 1er étape de la phase b2 (pellicule de sensibilisation)
- 1 step of the step b 2 (film sensitization)
Le bain utilisé est un bain aqueux réalisé au moyen d'eau désionisée avec les concentrations suivantes :
- - chlorure d'étain 40 g/1
- - acide chlorhydrique 40 ml/1
- -
0,1 ml/1mouillant
- - tin chloride 40 g / 1
- - hydrochloric acid 40 ml / 1
- - wetting 0.1 ml / 1
Le dépôt est effectué à température ambiante pendant 10 minutes. Il est suivi de deux rinçages à l'eau désionisée. On obtient une très fine pellicule d'étain apte à favoriser les réactions de réduction se développant à l'étape suivante.
- 2e étape de la phase b2 (pellicule catalytique)
- 2nd stage of phase b 2 (catalytic film)
Le bain aqueux est préparé à partir d'eau désionisée avec la conposition suivante :
- - nitrate d'argent : 10 g/1
- - hydroxyde d'ammonium : ajout jusqu'à
- - silver nitrate: 10 g / 1
- - ammonium hydroxide: added up to
La température du traitement est de 20° C et. sa durée de 10 secondes.The treatment temperature is 20 ° C and. its duration of 10 seconds.
Le dépôt est suivi de deux rinçages à l'eau désionisée ; on obtient une fine pellicule d'argent que catalyse le dépôt de l'étape suivante.
- 3e étape de la phase b2 (couche mince conductrice)
- 3rd stage of phase b 2 (conductive thin layer)
Le bain aqueux est préparé à partir d'eau désionisée, avec la composition suivante :
- - sulfate de cuivre 24 g/1
- - acide formique à 37 % 60 ml/1
- - sel de "Rochelle" 110 ml/1
- - soude 25 g/1
- - copper sulphate 24 g / 1
- - 37% formic acid 60 ml / 1
- - "Rochelle" salt 110 ml / 1
- - 25 g / 1 soda
La température du traitement est de 20° C et sa durée de 20 minutes.The treatment temperature is 20 ° C and its
Ce traitement est suivi de deux rinçages à l'eau désionisée et fournit une couche mince conductrice de cuivre.This treatment is followed by two rinses with deionized water and provides a thin conductive layer of copper.
A l'issu de cette phase (b2), la surface de chaque noyau présente l'aspect représenté à la figure 5c : la surface hors cavités des noyaux est recouverte d'une première pellicule très fine d'étain 27, d'une deuxième pellicule d'argent 28 plus épaisse, enfin d'une couche mince de cuivre 29 d'épaisseur plus importante (de l'ordre de 10 microns).At the end of this phase (b 2 ), the surface of each core has the appearance shown in FIG. 5c: the surface outside the cavities of the cores is covered with a first very thin film of
Cette phase d'électrodéposition est mise en oeuvre dans l'installation représentée à la figure 2, au moyen d'un bain aqueux préparé à partir d'eau désionée ayant la composition suivante :
- - sulfamate de nickel 350 g/1
- - acide borique 40 g/1
- - chlorure de nickel 5 g/1
- - agent anti-piqûre (tensio-actif) 0,1 ml/1 Les conditions du traitement ont été les suivantes :
- . température du bain 55° C
- .
3,5 à 4,5pH - . courant cathodique 10 A/dm2
- . durée 120 minutes
- - nickel sulfamate 350 g / 1
- - boric acid 40 g / 1
- - nickel chloride 5 g / 1
- - anti-bite agent (surfactant) 0.1 ml / 1 The treatment conditions were as follows:
- . bath temperature 55 ° C
- . pH 3.5 to 4.5
- . cathode current 10 A / dm 2
- . duration 120 minutes
Ce traitement est suivi de deux rinçages analogues aux précédents.This treatment is followed by two rinses similar to the previous ones.
Les billes obtenues présentent l'aspect schématisé à la figure 5d. La couhe conductrice 29 est recouverte d'une couche de nickel cristallisée 30 d'une épaisseur de l'ordre de 120 microns.The beads obtained have the appearance shown diagrammatically in FIG. 5d. The
L'ensemble de ces couches forme un revêtement qui possède des porosités ouvertes au niveau des cavités 26 du noyau de polystyrène.All of these layers form a coating which has open porosities at the level of the
Dans cet exemple, une couche supplémentaire est déposée par voie chimique sur la couche de nickel 30 en vue d'améliorer la resistance à la corrosion des billes. Cette couche supplémentaire qui est schématisée en 31 à la figure 5f préserve le caractère poreux du revêtement et peut donc être déposée avant la dissolution des noyaux.In this example, an additional layer is deposited chemically on the
Les billes sont immergées au moyen d' l'installation de la figure 1, dans un bain aqueux préparé à partir d'eau désionisée, contenant des produits disponibles dans le commerce (fabrication par "Frappaz Imaza")
- - "Enplate 418 A" : 60 ml/1
- - "Enplate 418 B" : 90 ml/1
- - "Enplate 418 A": 60 ml / 1
- - "Enplate 418 B": 90 ml / 1
La température du bain a été portée à 98° C et le traitement a été suivi par deux rinçages à l'eau désionisée et par un séchage en étuve.The temperature of the bath was brought to 98 ° C. and the treatment was followed by two rinses with deionized water and by drying in an oven.
On réalise ainsi sur le revêtement poreux un dépôt chimique anti-corrosif d'alliage microcristallisé nickel/phosphore ; l'épaisseur de ce dépôt est d'environ 5 microns.An anti-corrosion chemical deposit of microcrystallized nickel / phosphorus alloy is thus produced on the porous coating; the thickness of this deposit is approximately 5 microns.
Cette phase consiste à immerger les billes au moyen de l'installation de la figure 1, dans un solvant pur de perchloréthylène, pendant 30 minutes (figure 5f).This phase consists in immersing the beads by means of the installation of FIG. 1, in a pure solvent of perchlorethylene, for 30 minutes (FIG. 5f).
A l'issu du traitement les noyaux sont totalement dissous, et les billes sont ensuite séchées en étuve.At the end of the treatment, the nuclei are completely dissolved, and the beads are then dried in an oven.
Au terme du traitement, on obtient des billes telles que schématisées 32, possédant un diamètre de l'ordre de 6 mm ayant chacune une peau continue exempte de discontinuité macroscopiques.At the end of the treatment, beads are obtained as shown diagrammatically 32, having a diameter of the order of 6 mm, each having a continuous skin free of macroscopic discontinuity.
Des essais de compression ont été réalisés sur ces billes et ont permis de constater une résistance à la compression élevée et un domaine de plasticité étendu puisqu'aucune rupture n'a été obtenue sous la charge maximum de,12 bars, les billes s'écrasant progressivement à partir d'environ 3 bars.Compression tests have been carried out on these balls and have made it possible to note a high compressive strength and a wide range of plasticity since no rupture was obtained under the maximum load of 12 bars, the balls crashing gradually from around 3 bars.
Cette excellente plasticité confère aux billes une bonne absorption d'énergie au choc.En outre la couche supérieure leur donne une excellente résistance à la corrosion.This excellent plasticity gives the balls good absorption of impact energy, and the upper layer gives them excellent corrosion resistance.
Il est à noter que les billes présentent des caractéristiques physicochimiques très homogènes, les essais ayant donné une dispersion très faible des résultats.It should be noted that the beads have very homogeneous physicochemical characteristics, the tests having given a very low dispersion of the results.
Dans cet exemple les phases (a) (bl), (b2) (b3) sont identiques à celles de l'exemple 1. La phase de dissolution des noyaux (c) est ensuite mise en oeuvre comme dans cet exemple 1.In this example, the phases (a) (b l ), (b 2 ) (b 3 ) are identical to those of example 1. The phase for dissolving the nuclei (c) is then carried out as in this example 1 .
On réalise ensuite le dépôt d'une couche compacte métallique (telle que symbolisée en 33 à la figure 6a) dans l'installation des figures 3 et 4.Next, a compact metallic layer (as symbolized at 33 in FIG. 6a) is deposited in the installation of FIGS. 3 and 4.
Ce dépôt par trempage est réalisé en disposant dans le creuset 14 un bain en fusion de fer/chrome, de composition 75/25 à une température de 1520° C.This deposition by dipping is carried out by placing in the crucible 14 a molten iron / chromium bath, of composition 75/25 at a temperature of 1520 ° C.
L'enceinte 10 est remplie d'une atmosphère réductrice formée par de l'azote. Le temps de séjour des billes dans le bain peut être évalué à 2/10 à 3/10 seconde.The
On obtient un dépôt d'alliage cristallisé fer/chrome d'une épaisseur de l'ordre de 100 microns, qui supprime la porosité des billes et leur fournit de bonnes caractéristiques mécaniques à chaud.A deposit of crystallized iron / chromium alloy with a thickness of the order of 100 microns is obtained, which removes the porosity of the beads and provides them with good mechanical properties when hot.
Les billes ainsi obtenues sont ensuite soumises à un dépôt chimique en phase vapeur (C. V. D.) de type traditionnel en vue de les revêtir d'un dépôt d'oxyde de silicium (symbolisé en 34 à la figure 6h). Un tel dépôt de surface dont l'épaisseur est de l'ordre de 10 microns confère à la bille un caractère isolant sur le plan électrique et une bonne capacité de résistance à la corrosion.The beads thus obtained are then subjected to a chemical vapor deposition (CVD) of the traditional type with a view to coating them with a deposit of silicon oxide (symbolized at 34 in FIG. 6h). Such a surface deposit whose thickness is of the order of 10 microns gives with the ball an electrically insulating character and a good capacity of resistance to corrosion.
Ainsi le procédé de l'invention permet d'obtenir des billes (et plus généralement des corps creux) qui sont aptes à répondre aux exigences des applications visées : caractéristiques mécaniques, électriques, thermiques, magnétiques, élastiques...Thus the process of the invention makes it possible to obtain balls (and more generally hollow bodies) which are able to meet the requirements of the targeted applications: mechanical, electrical, thermal, magnetic, elastic characteristics, etc.
Le tableau de la figure 7 illustre les larges possibilités de choix qu'autorise le procédé.The table in FIG. 7 illustrates the wide possibilities of choice that the process allows.
Claims (22)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT86201286T ATE42774T1 (en) | 1985-07-25 | 1986-07-22 | METHOD FOR MANUFACTURING CLOSED AND SEAMLESS HOLLOW BODIES, HOLLOW BODIES MANUFACTURED ACCORDING TO THE METHOD AND DEVICE FOR MANUFACTURING HOLLOW BULLETS. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8511747 | 1985-07-25 | ||
FR8511747A FR2585373B1 (en) | 1985-07-25 | 1985-07-25 | PROCESS FOR THE MANUFACTURE OF HOLLOW, CLOSED AND CONTINUOUS BODIES, HOLLOW BODIES OBTAINED AND INSTALLATION FOR USE IN THE CASE OF HOLLOW BALLS |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0212712A1 true EP0212712A1 (en) | 1987-03-04 |
EP0212712B1 EP0212712B1 (en) | 1989-05-03 |
Family
ID=9321841
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86201286A Expired EP0212712B1 (en) | 1985-07-25 | 1986-07-22 | Process for manufacturing seamless hollow bodies, hollow bodies obtained by this process and apparatus used in these hollow spheres |
Country Status (6)
Country | Link |
---|---|
US (1) | US4722770A (en) |
EP (1) | EP0212712B1 (en) |
JP (1) | JPH0776435B2 (en) |
AT (1) | ATE42774T1 (en) |
DE (1) | DE3663153D1 (en) |
FR (1) | FR2585373B1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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FR2672652A1 (en) * | 1991-02-12 | 1992-08-14 | Lacroix E Tous Artifices | DAMPING SYSTEM ESPECIALLY FOR WEAPON SYSTEMS. |
EP0794341A1 (en) * | 1996-03-06 | 1997-09-10 | Skf Gmbh | Bearing for rolls |
Families Citing this family (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IN174705B (en) * | 1988-09-09 | 1995-02-18 | Daya Ranjit Senanayake | |
JPH06207294A (en) * | 1990-12-18 | 1994-07-26 | Taiho Kogyo Kk | Production of porous hollow metal having many minute ruggednesses on surface |
NL9200350A (en) * | 1992-02-26 | 1993-09-16 | Stork Screens Bv | METHOD FOR MANUFACTURING A METAL FOAM AND OBTAINED METAL FOAM. |
EP0873209A1 (en) * | 1995-12-13 | 1998-10-28 | Robert Baum | Method for producing hollow article and article produced thereby |
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FR351060A (en) * | 1905-01-27 | 1905-07-03 | Fred Anton Voelke | How to make seamless hollow objects |
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FR1311777A (en) * | 1961-04-28 | 1962-12-14 | Le Ministre Des Armees Directi | Method for manufacturing hollow bodies with constant wall thickness |
US4464231A (en) * | 1980-10-22 | 1984-08-07 | Dover Findings Inc. | Process for fabricating miniature hollow gold spheres |
JPS5935695A (en) * | 1982-08-20 | 1984-02-27 | Sanyo Electric Co Ltd | Production of porous nickel body |
JPS5935696A (en) * | 1982-08-20 | 1984-02-27 | Sanyo Electric Co Ltd | Production of porous nickel body |
-
1985
- 1985-07-25 FR FR8511747A patent/FR2585373B1/en not_active Expired - Lifetime
-
1986
- 1986-07-22 EP EP86201286A patent/EP0212712B1/en not_active Expired
- 1986-07-22 AT AT86201286T patent/ATE42774T1/en not_active IP Right Cessation
- 1986-07-22 DE DE8686201286T patent/DE3663153D1/en not_active Expired
- 1986-07-24 US US06/888,855 patent/US4722770A/en not_active Expired - Lifetime
- 1986-07-24 JP JP61174709A patent/JPH0776435B2/en not_active Expired - Lifetime
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR351060A (en) * | 1905-01-27 | 1905-07-03 | Fred Anton Voelke | How to make seamless hollow objects |
Non-Patent Citations (1)
Title |
---|
CHEMICAL ABSTRACTS, vol. 101, 1984, page 470, abstract nos. 62625v, 62626, Columbus, Ohio, US; & JP-A-59 35 695 (SANYO ELECTRIC CO. LTD.) 27-02-1984, & JP-A-59 35 696 (SANYO ELECTRIC CO. LTD.) 27-02-1984 * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2672652A1 (en) * | 1991-02-12 | 1992-08-14 | Lacroix E Tous Artifices | DAMPING SYSTEM ESPECIALLY FOR WEAPON SYSTEMS. |
EP0499526A1 (en) * | 1991-02-12 | 1992-08-19 | Etienne Lacroix - Tous Artifices Sa | Damping system for weapon systems |
EP0794341A1 (en) * | 1996-03-06 | 1997-09-10 | Skf Gmbh | Bearing for rolls |
Also Published As
Publication number | Publication date |
---|---|
FR2585373A1 (en) | 1987-01-30 |
JPS6286190A (en) | 1987-04-20 |
FR2585373B1 (en) | 1990-05-04 |
DE3663153D1 (en) | 1989-06-08 |
US4722770A (en) | 1988-02-02 |
ATE42774T1 (en) | 1989-05-15 |
EP0212712B1 (en) | 1989-05-03 |
JPH0776435B2 (en) | 1995-08-16 |
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