EP2569092B1 - Assembly for painting objects - Google Patents

Description

The present invention relates generally to the field of assemblies for painting parts using powder paint.

More particularly, the invention relates to an assembly for painting parts, comprising a powder paint spraying device.

Powder paint is used in place of paint in liquid form because it has advantages including that of not requiring a solvent. In general, the powder paint is deposited on the part to be painted, then the part thus covered is baked so as to gel the paint and to allow it to stick to the part once it has cooled down.

The document US 2002/0071906 A1 describes an assembly according to the preamble of claim 1.

In this context, the present invention aims to provide an assembly for painting parts to simplify the use of powder paint.

For this purpose, the invention proposes an assembly according to claim 1.

For the understanding of the invention, the term "gelling" denotes the change of state of the powder paint from its state of powdery powder to a viscous liquid state, this change of state occurring for temperatures greater than or equal to the first threshold. temperature, knowing that the first temperature threshold is lower than the second temperature threshold. The gelled paint has the appearance of a viscous liquid, while in its powdery state it takes the form of solid grains.

The powder paint spray is advantageous because it eliminates the need for solvents that we have in the case of liquid paints.

In addition, the introduction of powder paint into a hot air stream makes it possible to form a paint gel during the transport of the paint by the flow of hot air. The paint thus gelled and driven by the flow of hot air can be projected towards the piece to be painted and settle there in its gelled state and without the obligation to cook the piece to allow adhesion on the powder paint .

The fact of causing the gel paint in the flow of hot air makes it possible to give the paint on the one hand a speed and a kinetic energy favorable to its grip on the part to be painted and on the other hand allows a rise in temperature surface of the painted part which reduces the risk of heat shock between the gelled paint and the piece to paint and also promotes the grip of the paint. During its impact against the piece to be painted, the gelled paint spreads over the piece to marry the surface (the gel paint spreads on the piece much more easily than when it impacts the powder paint on the piece, the catch so is better).

Once the gelled paint deposited on the piece, it cools down and the piece is covered with a layer of paint from a powder paint without it having to be baked, or use solvents to apply it.

According to the invention, said means for producing the hot gas flow comprise a chamber provided with an air inlet and an air outlet nozzle and air heating means arranged between said air flow nozzle and an air outlet nozzle. air inlet and said air outlet nozzle.

With this embodiment of the invention, said gas flow is a flow of hot air, which is economical to implement because the gas flow is obtained by heating the air.

For the implementation of the invention, it is ensured that said means for introducing powder paint comprise at least one external nozzle located outside said chamber of said means for producing the hot gas stream, this external nozzle being oriented so that the powder paint introduction zone is located at the periphery of the air outlet nozzle.

This aspect is interesting because it makes it possible to introduce powder paint into the hot air flow while keeping the external nozzle away from the flow of hot air circulating in the chamber, which limits the heating of this nozzle and reduces the risk that the paint will gel under the effect of heat before being introduced into the airflow. Such gelation at the nozzle is indeed undesirable because it may be the cause of a sticking of the paint on the nozzle once the paint has cooled which can lead to at least partial plugging of the outer nozzle . It is understood that the paint catch on the outer nozzle is to be avoided because it changes the flow characteristics of the paint in this nozzle.

This also allows the introduction of ungelled paint powder in the hot air flow, the gelation of the powder paint involved during the training of the powder by the hot air flow. It has been noted that the non-gelled paint grains are easily distributed in the flow of hot air and their gelling in this flow makes it possible to obtain a gelled paint directly applicable to the workpiece to be painted.

Preferably, in order to implement this embodiment of the invention, this external nozzle is made to be annular and surrounds the air outlet nozzle, and this external nozzle is also made to include an annular baffle adapted to orienting the paint powder from the outer nozzle towards a central main axis of the air outlet nozzle.

Thus the powder is introduced concentrically into the hot gas stream which promotes its distribution over the entire section of hot gas flow.

According to the invention, the outer nozzle is made to comprise a paint powder inlet pipe oriented so as to create a flow of swirling paint powder at the interior of the outer nozzle and a swirling axis of rotation parallel to a main axis of powder outlet of the outer nozzle. The fact of creating such a vortex of paint powder in the annular outer nozzle and along a vortex axis parallel to a powder outlet axis makes it possible to have a homogeneous distribution of the paint powder all around the heated gas stream. promotes the homogeneous distribution of this powder in the heated gas stream.

Preferably, for the implementation of the invention, it is ensured that the means for producing a hot gas flow comprise a heat source disposed in said chamber, between said air inlet and said air outlet nozzle. .

This provision of the heat source is advantageous because it allows the heating of the gas flow without disturbing the flow of the paint in the gas stream since the heat source is upstream of the paint introduction zone in the gas flow.

For the implementation of the invention, it is also possible to so that said heat source is an electrical resistance.

The electrical resistance is useful because it allows a control of the temperature variation by a remote control of the heat source such as an electrical current dimmer of the supply current of the resistor.

Preferably, it is made that the means for producing a hot gas stream comprise a turbine powered by a motor, so as to generate a gas stream which is in this case an air flow.

Preferably, for the implementation of any of the aforementioned embodiments of the invention, it is ensured that the storage means of said powder paint comprise a powder reserve with means for forming a bed fluidized paint powder.

This embodiment makes it possible to improve the homogeneity of the powder paint conveyed from the storage means to the introduction means into said gaseous flow of the powder paint. This fluidized bed also promotes the delivery of powder paint avoiding that the powder agglomerates in the storage means.

For the implementation of the invention it is ensured that the assembly according to the invention comprises a compressor connected to said storage means and adapted to generate a compressed gas flow to force the passage of powder paint storage means to the introduction means in said gaseous flow of the powder paint.

Preferably, the same compressor is connected to said storage means so as to force the movement of at least a portion of the powder paint stored therein and to form said fluidized bed.

For the implementation of the invention it is ensured that the assembly comprises polymerizable paint in powder form having a gelling temperature between said first and second temperature thresholds and a polymerization reaction initiation temperature. also between these first and second temperature thresholds.

The choice of a paint having gelling and polymerization temperatures between the first and second heating thresholds of the gas stream allows the aid of the assembly according to the invention comprising this paint to perform on the one hand gelling and secondly to initiate the polymerization reaction during the transport of the paint in the hot gas stream.

The heating of the piece to be painted is thus limited since lower than the second temperature threshold, this which limits the risk of degradation of this room by heating effect.

Preferably, said first temperature threshold is greater than or equal to 60 ° C and preferably greater than or equal to 70 ° C and said second threshold, which is greater than the first threshold, is less than or equal to 200 ° C and preferably lower than or equal to 130 ° C, said first and second thresholds thus being preferably between 70 ° C and 130 ° C.

Limiting the second temperature threshold below 200 ° C. and preferentially below 130 ° C. makes it possible to limit the energy consumption necessary for heating the gas flow while allowing a temperature that is sufficient for gelling and the curing of paint while preserving the piece to paint.

Preferably, it is arranged that the assembly according to the invention comprises paint recycling means comprising a suction arranged to be placed at a distance from the introduction means in said gaseous flow of powder paint.

Thus the gel paint which has not been fixed on the piece to be painted can be recovered by the suction to be optionally recycled.

The advantage of such a suction is to create a flow of air sucking the powder and promoting its cooling and thus its solidification. Once solidified the powder has the advantage of being less adherent to the surfaces which facilitates its recycling by suction.

In a preferred embodiment of the assembly according to the invention, it is furthermore provided that it comprises means for preparing the surfaces to be painted, such as sandblasting, scrubbing or cryogenics, the advantage of which is to allow cleaning of the part to be painted before projecting on this piece of gelled paint powder.

Preferably for implementing the assembly for painting parts according to any one of the aforementioned embodiments it is made to include an enclosure formed of foldable walls and said means for introducing into said gaseous flow of paint powder are inside said enclosure.

This embodiment using foldable walls makes it possible to define a paint booth that can be easily stored for example to be transported.

Preferentially, the invention also relates to a vehicle comprising the assembly according to the invention so as to allow transport thereof.

In this embodiment, the assembly according to the invention can be easily moved to the places where it is desired to paint parts.

Preferably, this embodiment of the invention is implemented so that said foldable walls are attached to a cabin of the vehicle and the means for producing a hot gas stream and the storage means of said powder paint are carried in the vehicle cabin.

• la figure 1 représente un véhicule 30 doté d'une cabine 31 portant l'ensemble selon l'invention pour la peinture de pièces, ce mode de réalisation est prévu pour permettre une mobilité de l'ensemble avec la création d'une enceinte à parois pliables 29 permettant d'abriter l'objet à peindre 2 et à protéger l'environnement à l'extérieur de l'enceinte de peinture 28, sur cette figure 1, on voit que l'ensemble pour la peinture 1 selon l'invention comporte un dispositif de projection de peinture 3, des moyens de recyclage de la peinture 25 permettant d'aspirer la peinture non fixée sur la pièce 2 et des moyens de préparation des surfaces 27 permettant de nettoyer la pièce avant de la peindre ; le moyen de recyclage comporte une bouche d'aspiration qui est disposée pour que la pièce 2 à peindre soit entre cette bouche et le dispositif de projection de peinture, de cette manière la peinture qui ne s'est pas fixée sur la pièce 2 et qui peut être polymérisée peut être aspirée pour être recyclée ;
• la figure 2 présente le dispositif de projection 3 de peinture en poudre 32 qui comporte des moyens de stockage 6 de la peinture en poudre 32, ces moyens de stockage permettant de créer un lit fluidisé de peinture en poudre pour la rendre homogène avant son acheminement au travers des moyens d'introduction de peinture 7 dans le flux gazeux chaud 5 ; on voit sur cette figure 2 que le flux gazeux 5 est un flux d'air chaud généré par un moyen de production 4 du flux qui comprend une chambre 9 dotée d'une entrée d'air 10, une buse de sortie d'air 11, et une turbine 21 actionnée à rotation par un moteur électrique 22 de manière à générer le flux d'air 5 de l'entrée 10 vers la buse de sortie d'air 11, le moyen de production 4 de flux gazeux chaud 5 comporte en outre une résistance électrique 20 placée entre la turbine 21 et la buse de sortie 11 pour chauffer l'air en aval de la turbine 21 et du moteur 22 ;
• la figure 3 présente sensiblement les mêmes éléments que ceux de la figure 1, mais permet de voir une utilisation de l'ensemble selon l'invention 1 pour peindre un objet sans avoir à le déplacer ; Dans le cas de cette figure 3 c'est l'ensemble 1 qui est déplacé et les parois 29 de l'enceinte 28 sont dépliées autour de l'objet 2 qui est ici un portail ; On voit bien sur cette figure 3 qu'il y a un avantage à utiliser l'ensemble 1 selon l'invention car on peut peindre avec des poudre donc sans nécessité de solvants pour maintenir la peinture liquide avant séchage, et sans pour autant nécessiter un four pour polymériser la peinture en poudre après l'avoir déposée sur l'objet ;
• la figure 4 montre une portion d'un ensemble ne faisant pas partie de l'invention qui comporte lesdits moyens de stockage 6 de peinture en poudre 32, une alimentation en air comprimé de ce moyen de stockage 6 par un compresseur 24 de manière à former un lit fluidisé de peinture en poudre 23 ; on voit également sur cette figure 4 que ce même compresseur 24 peut être utilisé pour alimenter un circuit de refroidissement 18 en air frais de la buse interne 16 qui permet de libérer la peinture en poudre dans la chambre 9 des moyens de production de flux gazeux chaud 5 dans ce mode de réalisation qui ne fait pas partie de l'invention, on a une buse interne 16 pour introduire la peinture dans le flux gazeux chaud 5 à l'intérieur de la chambre 9 ; selon l'invention et comme on le voit sur la figure 6, l'autre alternative est d'introduire cette peinture en poudre dans le flux gazeux chaud sortant de cette chambre 9 en sortie de la buse de sortie d'air 11. On forme ainsi le flux 35 dans lequel sont présentes des particules de peinture gélifiées sous l'effet de la chaleur comprise entre (60 °C) et 130°C ;
• la figure 5 montre en détail le dispositif de projection 3 de peinture de la figure 4 avec un grossissement permettant de voir les grilles de l'entrée d'air 10 permettant de filtrer l'air entrant dans la chambre 9 et le circuit de refroidissement 18 avec ses entrée et sortie 19a, 19b de fluide de refroidissement qui est en l'occurrence de l'air provenant d'un compresseur ; Sur cette figure 5 qui ne fait pas partie de l'invention, la zone d'introduction 8 de peinture dans le flux gazeux chaud 5 est à l'intérieur de la chambre 9 car on utilise une buse interne 16 pour introduire la peinture en poudre ;
• la figure 6 montre également en détail un dispositif de projection 3 de peinture selon l'invention.
  La zone d'introduction de peinture 8 dans le flux gazeux chaud est à l'extérieur de la chambre 9 car on utilise une buse externe 13 fixée sur un déflecteur annulaire 14 prévu pour orienter la peinture vers le flux 5, de sorte que la buse 13 est orientée d'un angle Téta supérieur à 30° par rapport à l'axe XX axe principal central de la buse de sortie d'air 1, comme cela est clairement illustré par la figure 6. Cela permet d'introduire des particules de peinture jusqu'à cet axe X-X favorisant une répartition homogène de la peinture dans le flux. Ce déflecteur 14 et la buse externe 13 sont agencés de manière à faire tourbillonner la peinture en poudre à l'intérieur de la buse 13 pour lui conserver une homogénéité de répartition sur toute la section de la sortie de buse externe 13. Selon ce mode de réalisation, le dispositif 3 comporte également des grilles d'entrée d'air 10 permettant de filtrer l'air entrant dans la chambre 9, mais il n'y a pas ici de circuit de refroidissement de la buse externe 13 car celle-ci est relativement distante de la zone chaude de la chambre 9.

Other characteristics and advantages of the invention will emerge clearly from the description which is given hereinafter, by way of indication and in no way limitative, with reference to the appended drawings, in which:

• the figure 1 represents a vehicle 30 having a cabin 31 carrying the assembly according to the invention for painting parts, this embodiment is provided to allow mobility of the assembly with the creation of a foldable wall enclosure 29 allowing to house the object to be painted 2 and to protect the environment outside the paint enclosure 28, on this figure 1 it can be seen that the assembly for the paint 1 according to the invention comprises a paint spraying device 3, paint recycling means 25 for sucking the non-fixed paint onto the part 2 and means for preparing the paint surfaces 27 for cleaning the room before painting; the recycling means comprises a suction mouth which is arranged so that the piece 2 to be painted is between this mouth and the paint spraying device, in this way the paint which has not been fixed on the piece 2 and which can be polymerized can be sucked for recycling;
• the figure 2 presents the powder paint projection device 32 which comprises storage means 6 for the powder paint 32, these storage means making it possible to create a fluidized bed of powder paint to make it homogeneous before it is conveyed through the means introducing paint 7 into the hot gas stream 5; we see on this figure 2 that the gas stream 5 is a stream of air generated by a production means 4 of the flow which comprises a chamber 9 provided with an air inlet 10, an air outlet nozzle 11, and a turbine 21 rotated by an electric motor 22 so as to generate the flow of air 5 from the inlet 10 to the air outlet nozzle 11, the hot gas flow production means 4 further comprises an electrical resistance 20 placed between the turbine 21 and the outlet nozzle 11 for heating the air downstream of the turbine 21 and the motor 22;
• the figure 3 substantially the same elements as those of the figure 1 but allows to see a use of the assembly according to the invention 1 to paint an object without having to move it; In the case of this figure 3 it is the assembly 1 which is moved and the walls 29 of the enclosure 28 are unfolded around the object 2 which is here a portal; We see well on this figure 3 that there is an advantage to use the assembly 1 according to the invention because one can paint with powder so without the need for solvents to maintain the liquid paint before drying, and without requiring an oven to polymerize the powder paint after depositing it on the object;
• the figure 4 shows a portion of an assembly not forming part of the invention which comprises said powder paint storage means 32, a supply of compressed air to this storage means 6 by a compressor 24 so as to form a fluidized bed powder paint 23; we also see on this figure 4 that the same compressor 24 can be used to supply a fresh air cooling circuit 18 of the internal nozzle 16 which makes it possible to release the powder paint in the chamber 9 of the hot gas flow generating means 5 in this mode of embodiment which does not form part of the invention, there is an internal nozzle 16 for introducing the paint into the hot gas stream 5 inside the chamber 9; according to the invention and as seen on the figure 6 the other alternative is to introduce this powder paint into the hot gas stream coming out of this chamber 9 at the outlet of the air outlet nozzle 11. This forms the flow 35 in which there are present gelled paint particles under the effect of heat between (60 ° C) and 130 ° C;
• the figure 5 shows in detail the projection device 3 painting of the figure 4 with a magnification to see the grilles of the air inlet 10 for filtering the air entering the chamber 9 and the cooling circuit 18 with its inlet and outlet 19a, 19b of cooling fluid which is in the occurrence of air from a compressor; On this figure 5 which is not part of the invention, the paint introduction zone 8 in the hot gas stream 5 is inside the chamber 9 because an internal nozzle 16 is used to introduce the powder paint;
• the figure 6 also shows in detail a projection device 3 of paint according to the invention.
  The paint introduction zone 8 in the hot gas stream is outside the chamber 9 because an external nozzle 13 is used which is fixed on an annular baffle 14 intended to direct the paint towards the stream 5, so that the nozzle 13 is oriented by a Teta angle greater than 30 ° with respect to the central axis XX central axis of the air outlet nozzle 1, as is clearly illustrated by the figure 6 . This makes it possible to introduce paint particles up to this axis XX favoring a distribution homogeneous paint in the stream. This deflector 14 and the outer nozzle 13 are arranged to swirl the powder paint inside the nozzle 13 to maintain distribution homogeneity over the entire section of the outer nozzle outlet 13. According to this embodiment, the device 3 also has air intake grids 10 for filtering the air entering the chamber 9, but there is no here cooling circuit of the outer nozzle 13 because it is relatively distant from the hot zone of the room 9.

As can be seen in each of the embodiments described in Figures 4, 5 , 6 , the paint spraying device 3 has a control 34 in the form of a trigger and controlling the speed of the gas stream 5 in the chamber 9 and / or the selective delivery of the powder paint by the paint introduction means 7 This trigger 34 may for example control the heating of the electrical resistance 20 and / or the speed of rotation of the motor 22 driving the turbine 21. In these embodiments, an electric cable 36 for supplying electricity to the Trigger, the turbine engine and the heating resistor 20. Also, it can be seen that the chamber 9 is connected to a gripping handle allowing the user to move it to orientate its exit and the hot flow comprising painting in the direction desired.

Ideally the introduction means 7 comprise at least one flexible pipe 37 of length greater than 1 meter and connecting these introduction means 7 to the storage means 6. This separation via the flexible pipe 37 allows to leave the reserve of paint which is heavy (storage means with its fluidized bed system) while allowing the user to move the chamber 9 and the introduction means 7 to orient the nozzles relative to the piece to be painted.

It should be noted that in accordance with the embodiment of the figure 4 , the compressor 24 which generates compressed air can be connected to the chamber 9 of the hot gas flow generating means 5 and in this case replaces the motor 22 and the turbine 4, a controlled valve for selectively controlling the opening and closing of this link. The air flow generated by this compressor is heated in the chamber by the electrical resistance located upstream of the zone 8 where the powder paint is introduced.

This same compressor 24 can also be connected to the storage means 6 as seen on the figure 4 in order firstly to generate the fluidized bed of paint and secondly to create a flow for conveying this powder paint towards the flow of hot air generated in the chamber 9 of the gas flow production means 4 hot. This connection can also be selectively controlled by a valve.

In the embodiment not forming part of the invention, where the introduction of paint is done in the chamber 9 by an internal nozzle 16 (see FIG. figures 2 , 4, 5 ), this compressor 24 can also be connected to the cooling circuit 18 as seen in FIG. figure 4 in order to cool the internal nozzle 16 and the paint that passes through it. This connection can be selectively controlled by a separate valve whose function is the regulation of the temperature of the inner nozzle 16. In this embodiment a temperature sensor can be implanted to evaluate the temperature of the internal nozzle 16 and regulate the opening of the valve according to the rated temperature.

• température du flux gazeux 5 (qui détermine la température de chauffe de la peinture et donc sa vitesse de gélification et éventuellement de polymérisation) ; et/ou
• de vitesse V du flux gazeux en sortie de la buse de sortie d'air 11 hors de la chambre 9 (qui détermine la vitesse d'acheminement de la poudre dans le flux et donc sa vitesse d'impactage de la peinture sur la pièce 2 à peindre) ; et/ou
• le flux de peinture en poudre 32 acheminé via les moyens d'introduction 7 vers la zone d'introduction 8 de peinture en poudre 32 dans le flux 5 (par exemple cette consigne de flux peut être la masse de peinture par unité de temps), ce paramètre détermine la quantité de peinture délivrée par unité de temps grâce à l'ensemble selon l'invention.

Preferably the assembly according to the invention comprises a regulation provided with one or two control panels 33 (a panel 33 can be fixed outside the chamber 9 and the other panel 33 can be fixed to the storage means 6 ) on which the user can set instructions for:

• temperature of the gas stream 5 (which determines the heating temperature of the paint and therefore its gelling rate and optionally polymerization); and or
• velocity V of the gaseous flow at the outlet of the air outlet nozzle 11 out of the chamber 9 (which determines the rate of delivery of the powder into the flow and therefore its rate of impact of the paint on the workpiece 2 to paint); and or
• the flow of powder paint 32 conveyed via the introduction means 7 to the introduction zone 8 of powder paint 32 into the stream 5 (for example this flow setpoint may be the mass of paint per unit of time), this parameter determines the quantity of paint delivered per unit time thanks to the assembly according to the invention.

This regulation with panel 33 is preferably connected to each of said valve and temperature sensors above and possibly flow rate sensors or pressure so as to control the achievement of the aforementioned instructions.

• que la peinture en poudre possède une granulométrie moyenne comprise entre 5µm et 30µm, une masse volumique comprise entre 0,4 et 0,8 g/cm3 et, comme on le voit sur la figure 4,
• que la pièce à peindre 2 est à une distance de la buse 11, en l'occurrence entre 5 et 50 cm ;
• que la température du flux gazeux chaud 5, qui est en l'occurrence un flux d'air chaud, est supérieure ou égale aux températures de gélification et de déclenchement de polymérisation de la peinture, en l'occurrence entre 60 °C et 130°C ; et que
• la vitesse du flux d'air chaud 5 en sortie de buse de sortie d'air 11 est bien comprise entre 0,2 m/s et 20m/s ;

on réunit alors les conditions permettant d'impacter des particules de peinture gélifiée sur cette pièce 2, qui une fois polymérisées formeront une couche de peinture sur cette pièce 2.Making sure:

• that the powder paint has a mean particle size of between 5 μm and 30 μm, a density of between 0.4 and 0.8 g / cm 3 and, as can be seen in FIG. figure 4 ,
• the piece to be painted 2 is at a distance from the nozzle 11, in this case between 5 and 50 cm;
• that the temperature of the hot gas stream 5, which is in this case a flow of hot air, is greater than or equal to the gelation and paint curing temperatures of the paint, in this case between 60 ° C and 130 ° VS ; and
• the speed of the hot air flow 5 at the outlet of the air outlet nozzle 11 is between 0.2 m / s and 20 m / s;

the conditions enabling gelled paint particles to be impacted on this part 2, which once polymerized, will then form a layer of paint on this part 2.

Claims (6)

1. Assembly (1) for painting parts (2), comprising a device (3) for spraying powder paint (32), which comprises:

   - means (4) for generating a hot gas flow (5), which means are designed to generate a flow of hot air whose temperature is at least between first and second temperature thresholds;

   - means (6) for storing said powder paint (32);

   - means (7) for introducing powder paint (32) into said gas flow (5), these introducing means (7) being connected on one hand to said storage means (6) for drawing powder paint (32) therefrom and opening on the other hand in the direction of a powder paint (32) introduction zone (8) located so as to be oriented towards said hot gas flow (5) generated by said means (4) for generating a hot gas flow (5), said means (4) for generating the hot gas flow comprising a chamber (9) provided with an air inlet (10) and with an air outlet nozzle (11) and means (12) for heating the air, arranged between said air inlet (10) and said air outlet nozzle (11),

   said powder paint introducing means (7) comprising at least one outer nozzle (13) located outside said chamber (9) of said means for generating the hot gas flow and oriented such that the powder paint introduction zone (8) is located on the periphery of the air outlet nozzle (11), this outer nozzle (13) being secured to an annular deflector (14) for directing the paint towards the hot air flow (5), said outer nozzle (13) being oriented at an angle greater than 30° with respect to the central main axis XX of the air outlet nozzle (11), said deflector (14) and said outer nozzle (13) being arranged so as to cause the powder paint to swirl within said nozzle (13),
   the assembly being characterized in that said zone (8) for introducing paint into the hot gas flow is outside the chamber.
2. Assembly according to Claim 1, characterized in that the means (4) for generating a hot gas flow (5) comprise a heat source (20) arranged in said chamber (9), between said air inlet (10) of the chamber and said air outlet nozzle (11).
3. Assembly according to Claim 2, characterized in that said heat source is an electric resistance (20).
4. Assembly according to one of Claims 1 to 3, characterized in that the means (4) for generating a hot gas flow (5) comprise a turbine (21) set in rotation by an electric motor (22).
5. Assembly according to one of Claims 1 to 4, characterized in that the device (3) for spraying powder paint (32) comprises air inlet grilles (10) by means of which it is possible to filter the air entering the chamber (9).
6. Assembly according to at least one of Claims 1 to 5, characterized in that it comprises polymerizable paint in the form of powder (32), having a gelation temperature between said first and second temperature thresholds and a polymerization reaction initiation temperature also between these first and second temperature thresholds.

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