ELECTROSTATIC-PAINTING SYSTEM FOR METALLIC MANUFACTURED ARTICLES AND ASSOCIATED METHOD

Description

[0001] The present invention relates to an electrostatic-painting system for metallic manufactured articles such as aluminum sections, sheet, metallic structures and the like and to a method making use of such a system.

[0002] As known, there are different types of systems for painting aluminum sections while those commonly used are of three types, to wit:

• Vertical systems using the technique of vertical suspension of the aluminum sections. These systems have the advantage of high productivity with limited labor but the disadvantage of high cost, high energy consumption, much maintenance and difficult control of pretreatment before painting because the inline oven with two input-output mouths loses much heat with high energy consumption;
• Horizontal systems using the horizontal suspension technique for the aluminum sections. These systems have fair productivity (up to 25 hangers per hour), allow pretreatment off the line and are thus easy to control and display easy loading and unloading of the parts with accumulation zones. The disadvantages of such systems is in the use of an inline or accumulation oven which, having two input-output mouths, loses a large amount of heat with high energy consumption. In addition, for color change it is necessary to keep two or three empty hangers for translation of the two booths or, with fixed booths, it is necessary to have an additional space for the two-rail conveyor. The space occupied by the system is very great in relation to productivity; and
• Compact systems (Italian Patent No. 01244788 of 29^th August 1994) which are equipped with two parallel conveyors on which are fixed the hangers which carry the aluminum sections fastened horizontally. These systems have the advantages of occupying limited space, having a bell oven that consumes little energy, and one or two small painting booths. In this case the disadvantages are very low productivity, difficulty of loading and unloading parts, and having to work with the oven positioned over the heads of the operators and the poor safety for the operators who have to work in an environment with hanging bars which could fall during handling. The parts must be unloaded from the hangers while they are still very hot with clearly unfavorable working conditions for the operators. In addition, as the hangers are mounted on the overhead conveyors at the same pitch for all and it is not possible to have a small wheelbase because allowance must be made for passage of the booth for painting and space for the loading and unloading operators, a limited number of hangers can stay in the oven (usually 3 or 4) without optimizing use of the oven; these systems are thus suited for production of small lots since they can produce a maximum of 12 hangers per hour.

[0003] EP-A-0 980 716 discloses a painting system wherein a overhead conveyor for hangers and a further conveyor for floor carriers are present, with transfer means for transferring the workpieces from the first to the second conveyor, WO 02/072284 discloses a known arrangement of different, consecutive conveyors.

[0004] The general purpose of the present invention is to remedy the above mentioned shortcomings by making available a system and method for electrostatic painting of metallic manufactured articles with powders, which system and method would allow high hourly production (25 hangers per hour similar to or higher than a horizontal system) with a small system (similar to a compact system), and with limited used of labor while operating under optimal environmental conditions.

[0005] In view of this purpose it was sought to provide in accordance with the present invention a system for electrostatic painting of metallic manufactured articles as claimed by claim 1.

[0006] Again in accordance with the present invention it was sought to realize a method for electrostatic painting of metallic manufactured articles as claimed by claim 18.

[0007] To clarify the explanation of the innovative principles of the present invention and its advantages compared with the prior art there is described below with the aid of the annexed drawings a possible embodiment thereof by way of non-limiting example applying said principles. In the drawings:

FIG 1 shows an overall side view of a realization of the system in accordance with the present invention;

FIG 2 shows a plan view of the painting device; and

FIG 3 shows an overall side view of an alternative realization of the system in accordance with the present invention.

[0008] With reference to the figures, FIG 1 shows a preferred embodiment of the electrostatic-painting system 10 comprising the overhead loading conveyor 11, the overhead heat-treatment conveyor 12, the unloading overhead conveyor 13, the overhead transfer conveyor 14, the hot air bell-oven 15, the painting device 16 and the supporting structure 17. The conveyors 11, 12, 13, and 14 consist of two parallel chains (not shown) handled at the same speed. To the conveyors 11, 12, 13 and 14 are hooked a plurality of hangers 18 designed to support the manufactured metallic articles 19 to be painted. The loading conveyor 11, the unloading conveyor 13 and the heat-treatment conveyor 12 are accumulating conveyors that allow accumulation of a plurality of hangers in the loading zone, the unloading zone and the oven 15 respectively. The conveyor 12 is placed in the oven 15 while the unloading conveyor 13 and the loading conveyor 11 are outside the oven 15 near the outlet 21 and inlet 20 openings respectively of the oven. These openings 20 and 21 are positioned on the lower side of the bell oven 15. The overhead conveyor 14 is a transfer conveyor connecting the three accumulation conveyors 11, 12, 13 in a closed loop. The conveyor 14 has purposeful hooking and unhooking systems and at each step deposits and takes a part-carrying hanger 18 from each of the three accumulation conveyors 11, 12, 13. The connection between the unloading conveyor 13 and the loading conveyor 12 passes above the oven 15 as shown in FIG 1. The supporting structure 17 holds up the oven 15 in a superelevated position above the conveyors 11 and 13 and over the painting device 16. The oven 15 has dimensions such as to contain about ten hangers 18. The painting device 16 is positioned between the loading conveyor 11 and the oven inlet 20.

[0009] FIG 2 shows in detail a plan view of the painting device 16. This device includes a booth-carrier platform 30, two painting booths 31a and 31b, air suction means 32, a suction channel 33 and electronic translation speed control means for the booths 41 and suction intensity 40. Each booth 31a and 31b has two powder dispensers 34 for spraying metallic manufactured articles hung on the hangers 18. The booths have wheels 35 for translation from one part to the other of the booth-carrier platform 30 on a purposeful path so as to receive the hangers 18 in the booths in the space included between the two dispensers 34. The powder dispensers 34 are rectilinear in form and placed in a vertical position. They are inclined at an angle between 0° and 60° to the direction perpendicular to the booth translation direction. The translation path on the booth-carrier platform 30 is sufficiently long to allow one of the two booths, no. 31b, to stop in a rest position without interfering with the translational motion of the other booth 31a that is in the painting step. The suction channel 33 connects the suction means 32 with the entire painting booth running path along the booth-carrier platform 30 as shown in the figure. The channel 33 is normally closed on the platform 30 side and is opened at the position of the painting booth 31 so as to suck air only in the actual painting zone.

[0010] We shall now describe the painting process that uses the system 10.

[0011] The manufactured articles 19 are loaded manually onto the hangers 18 on the loading conveyor 11 that accumulates them in the inlet zone. Then the manufactured articles are sprayed with powder in the painting device 16. The painting booth 31a, in translating from one side to the other of the booth-carrier platform 30, receives the hangers 18 and the manufactured metallic article 19 in the space included between the two dispensers 34 which spray electrostatically charged powder over the entire surface of the manufactured articles 19. A sliding device (not shown in the figure) opens the suction channel 33 normally closed on passage of the booth 31a so that the painting powders are recovered and the direction of flow of the painting powders is optimized. Said powders are sprayed at an optimal angle thanks to the inclination of the dispensers 34. While the booth 31a is in the spraying step, the other booth 31b is available for cleaning and color change. The booth translation speed control means 41 make it possible to have high speed during arrival and leaving from the spraying zone and to adjust speed during spraying depending on the type of parts. The suction intensity control means 40 allow increase of suction in the spraying step so as to optimize power consumption of the suction means 32.

[0012] After being sprayed with the powders, the manufactured articles 19 enter through the opening 20 into the oven 15 for polymerization. In the oven 15 the manufactured articles are received on the accumulation conveyor 12. The oven 15 can contain about ten hangers 18 to allow simultaneous polymerization of a plurality of metallic manufactured articles 19. Heat treatment lasts between 15' and 30' and, once completed, the manufactured articles 19 come out of the oven through the opening 21 to be received on the unloading accumulation conveyor 13. Before being unhooked from the hangers 18, the manufactured articles 19 stop on the unloading conveyer 13 long enough to cool and allowing the operators to work under safe environmental conditions. Once unloaded, the hangers 18 are automatically carried back to the inlet conveyor 11 by means of the overhead transfer conveyor 14. The hangers can now be reloaded for another processing cycle.

[0013] FIG 3 shows an alternative embodiment of the system in accordance with the present invention. Said embodiment 110 comprises, similarly to the above described embodiment, a loading conveyor 111, a painting device 116, a heat-treatment conveyor 112, a hot-air bell-oven 115, an unloading conveyor 113, an overhead conveyor 114 for transfer of the hangers 118 hookable to the conveyors 111, 112, 113, 114. The alternative embodiment comprises in addition a pretreatment system 150 for the manufactured articles. This system 150 comprises the anodizing (or chromium plating) tanks 151, the rinsing tank 152 and the drying tank 153. The pretreatment system 150 is fitted between the loading conveyor 111 and the painting device 116 as shown in the figure.

[0014] After having described two embodiments of the present invention, the numerous advantages obtained as compared with the prior art such as high hourly production, limited use of space and excellent environmental conditions for the operators appear to be evident. Indeed, considering that the bell oven can receive up to ten part-carrying hangers and that polymerization time for the metallic manufactured articles varies between 15' and 30', an hourly production of approximately 25 to 30 hangers per hour is achieved, which is higher than the hourly production achievable with the prior art systems. Again, use of space is limited in relation to productivity since use of the bell oven is optimized thanks to the particular shape of the system embodiment realized. In addition, accumulation of the hangers leaving the oven on the unloading conveyor allows cooling of the manufactured articles painted and polymerized before intervention of the operators in the unloading zone. In this manner, the working environment is safer. The efficiency of the system is further improved by the capability of cleaning one of the two painting booths off-line without interrupting the manufacturing process which continues by making use of the other booth. Power consumption is also optimized thanks to complete utilization of the bell oven and reduced used of power for treatment of the inner atmosphere of the booth thanks to selective air suction in the spraying zone.

[0015] Naturally the above description of an embodiment applying the innovative principles of the present invention is given by way of non-limiting example of said principles within the scope of the exclusive right claimed here.

Claims

1. System for electrostatic painting of metallic manufactured articles comprising:

- a conveyor system for a plurality of hangers (18, 118) designed to carry metallic manufactured articles (19, 119); and

- a painting device (16, 116) for the manufactured articles and an oven (15, 115) traversed by said conveyor system for processing of the manufactured articles (19, 119) carried by the hangers (18, 118);

characterized in that the conveyor system comprises:

- a first conveyor (11, 111), or loading conveyor, for accumulation of the hangers (18, 118) outside and upstream of the oven (15, 115) for loading of the manufactured articles (19, 119) onto the hangers (18, 118);

- a second conveyor (13, 113), or unloading conveyor, for accumulation of the hangers (18, 118) outside and downstream of the oven (15, 115) for unloading of the manufactured articles (19, 119) from the hangers (18, 118);

- a third conveyor (12, 112), or heat-treatment conveyor, for accumulation of the hangers (18, 118) inside the oven (15, 115); and

- a fourth conveyor (14, 114), or transfer conveyor, connecting said first, second and third conveyors (11, 12, 13, 111, 112, 113) for transferring the hangers (18, 118) between them.

2. System according to claim 1, characterized in that said fourth conveyor (14, 114) connects the unloading conveyor (13, 113) to the loading conveyor (11, 111) passing over the oven (15, 115).

3. System according to claim 1, characterized in that the four conveyors (11, 12, 13, 14, 111, 112, 113, 114) are each made up of two parallel chains and move in step at the same speed.

4. System according to claim 1, characterized in that the oven (15, 115) is of hot-air bell type.

5. System according to claim 4, characterized in that the oven (15, 115) can contain more than one hanger (18, 118).

6. System according to claim 4, characterized in that the bell-type oven (15, 115) has an opening (20) for entry and an opening (21) for exit of the hangers (18, 118) on the lower side thereof.

7. System according to claim 1, characterized in that the painting device (16, 116) is traversed by said fourth transfer conveyor (14, 114) and is positioned between the loading conveyor (11, 111) and the heat-treatment conveyor (12, 112) in the oven (15, 115), with said painting device (16, 116) comprising a booth-carrier platform (30), at least two painting booths (31a, 31b) for the manufactured articles (19, 119), which are mounted movably on said platform (30), and suction means (32) connected to the painting booths (31a, 31b) for treatment of the internal atmosphere of the booth.

8. System according to claim 7, characterized in that the painting booths (31a, 31b) have means for translation onto the booth-carrier platform (30) in a direction parallel to a row of hangers (18, 118) and to receive said hangers (18, 118) inside them during the translation motion.

9. System according to claim 7, characterized in that each painting booth (31a, 31b) has in it two rectilinear and vertical powder dispensers (34) operating on opposite sides of the manufactured articles (19, 119) in the spraying step.

10. System according to claim 9, characterized in that the two dispensers (34) of each painting booth (31a, 31b) are inclined at an angle between 0° and 60° to the direction perpendicular to the translation direction of the booth (31a, 31b).

11. System according to claim 7, characterized in that the suction means (32) are fixed in relation to the booth-carrier platform (30) and outside it.

12. System according to claim 11, characterized in that the suction means (32) are connected to the booth-carrier platform (30) by means of a suction channel (33) extending along the entire running path of the painting booths (31a, 31b) on said booth-carrier platform (30).

13. System according to claim 12, characterized in that said suction channel (33) is normally closed on the side of the booth-carrier platform (30) and is opened upon passage of the booth (31a, 31b) by a sliding device to put the air suction means (32) selectively in communication with the atmosphere of the painting booths (31a, 31b).

14. System according to claim 7, characterized in that the two painting booths (31a, 31b) are guided on a single path on the platform (30) and the run of the booths (31a, 31b) is ample to the point of allowing at its ends stopping of one (31b) of the two booths in a rest position for cleaning while the other booth (31a) is in the spraying step.

15. System according to claim 7, comprising a control means (41) of translation speed of the painting booths.

16. System according to claim 7, characterized by comprising control means (40) of booth internal air suction intensity.

17. System according to claim 1, characterized by comprising a sub-system (150) for pretreatment of the manufactured articles (119) positioned between the loaded conveyor (111) and the painting device (116).

18. Method for electrostatic painting of metallic manufactured articles using the system according to claim 1, comprising the following steps:

- loading the metallic manufactured articles (19, 119) onto hangers (18, 118) on the loading conveyor (11, 111) outside and upstream of the oven (15, 115);

- spraying the metallic manufactured articles (19, 119) with electrostatically charged powders;

- transferring the painted manufactured articles (19, 119) onto the heat-treatment conveyor (12, 112) inside the oven (15, 115);

- heating the metallic manufactured articles (19, 119) until complete polymerization of the powders;

- transferring the polymerized manufactured articles (19, 119) onto the unloading conveyor (13, 113) outside and downstream of the oven (15, 115);

- unloading the manufactured articles (19, 119) from the hangers (18, 118) at said unloading conveyor (13, 113); and

- transferring the unloaded hangers (18, 118) from the unloading conveyor (13, 113) to the loading conveyor (11, 111) automatically by means of the transfer conveyor (14, 114).

19. Method according to claim 18, characterized in that the hangers (18, 118) stop on the unloading conveyor (13, 113) long enough for cooling of the manufactured articles (19, 119) before being manually unloaded from the painting system.

20. Method according to claim 18, characterized in that in the spraying step a single painting booth (31a) is used, with the other booth (32b) being available for cleaning and color change.

21. Method according to claim 18, characterized in that there is a pretreatment step with tanks between the charging step and the powder-spraying step.

Ansprüche

1. Elektrostatisches Lackiersystem für metallische Fertigartikel, umfassend:

- ein Fördersystem für eine Mehrzahl von Gehängen (18, 118) die für den Transport von metallischen Fertigartikeln (19, 119) ausgelegt sind; und

- eine Lackieranlage (16, 116) für die Fertigartikel und einen vom genannten Fördersystem durchquerten Ofen (15, 115) zur Bearbeitung der von den Gehängen (18, 118) geförderten Fertigartikel (19, 119);

dadurch gekennzeichnet, dass das Fördersystem umfasst:

- einen ersten Förderer (11, 111), oder beladenen Förderer , für das Sammeln der Gehänge (18, 118) außerhalb und vor dem Ofen (15, 115) zum Laden der Fertigartikeln (19, 119) auf den Gehängen (18, 118);

- einen zweiten Förderer (13, 113), oder unbeladenen Förderer, für das Sammeln von Gehängen (18, 118) außerhalb und nach dem Ofen (15, 115) zum Abladen der Fertigartikeln (19, 119) von den Gehängen (18, 118);

- einen dritten Förderer (12, 112), oder Förderer unter Wärmebehandlung, für das Sammeln von Gehängen(18, 118) innerhalb des Ofens (15, 115); und

- einen vierten Förderer (14, 114), oder Transferförderer, der den genannten ersten, zweiten und dritten Förderer (11, 12, 13, 111, 112, 113) verbindet, um die Gehänge (18, 118) untereinander zu überführen.

2. System nach Patentanspruch 1, dadurch gekennzeichnet, dass der genannte vierte Förderer (14, 114) den ungeladenen Förderer (13, 113) mit dem beladenen Förderer (11, 111) über dem Ofen (15, 115) vorbei verbindet.

3. System nach Patentanspruch 1, dadurch gekennzeichnet, dass die vier Förderer (11, 12, 13, 14, 111, 112, 113, 114) jeweils aus zwei parallelen Ketten bestehen und sich schrittweise mit der selben Geschwindigkeit bewegen.

4. System nach Patentanspruch 1, dadurch gekennzeichnet, dass der Ofen (15, 115) eine Art Heißluft-Glockenofen ist.

5. System nach Patentanspruch 4, dadurch gekennzeichnet, dass der Ofen (15, 115) mehr als ein Gehänge (18, 118) beinhalten kann.

6. System nach Patentanspruch 4, dadurch gekennzeichnet dass der Heißluft-Glockenofen (15, 115) eine Öffnung (20) als Eingang und eine Öffnung (21) als Ausgang für die Gehänge (18, 118) auf der unteren Seite besitzt.

7. System nach Patentanspruch 1, dadurch gekennzeichnet, dass die Lackieranlage (16, 116) vom genannten vierten Transferförderer (14, 114) durchquert wird und zwischen dem beladenen Förderer (11, 111) und dem Förderer (12, 112) unter Wärmebehandlung im Ofen (15, 115) positioniert ist, wobei das genannte Lackiersystem (16, 116) eine Kabinenplattform (30), mindestens zwei Lackierkabinen (31a, 31b) für die Fertigartikel (19, 119), welche auf der genannte Plattform (30) beweglich montiert sind, und Saugmittel (32)umfasst die mit den Lackierkabinen (31a, 31b) zur Behandlung der inneren Atmosphäre der Kabinen verbunden sind.

8. System nach Patentanspruch 7, dadurch gekennzeichnet, dass die Lackierkabinen (31a, 31b) Mittel zum Verstellen auf der Kabinenplattform (30) in einer Richtung parallel zu einer Reihe von Gehängen (18, 118) und zur Aufnahme der Gehänge (18, 118) innerhalb derselben während der Verstellbewegung besitzt.

9. System nach Patentanspruch 7, dadurch gekennzeichnet, dass jede Lackierkabine (31a, 31b) immer jeweils zwei geradlinige und vertikale Pulververteiler (34) besitzt, die auf gegenüberliegenden Seite der Fertigartikel(19, 119) beim Lackierabschnitt wirken.

10. System nach Patentanspruch 9, dadurch gekennzeichnet, dass die beiden Pulververteiler (34) einer jeder Lackierkabine (31a, 31b)unter einem Winkel zwischen 0° und 60° zur Richtung senkrecht zur Verstellrichtung der Kabinen (31a, 31b) geneigt sind.

11. System nach Patentanspruch 7, dadurch gekennzeichnet, dass die Saugmittel (32) fest gegenüber der Kabinenplattform (30) und außerhalb davon hängen.

12. System nach Patentanspruch 11, dadurch gekennzeichnet, dass die Saugmittel (32) der Kabinenplattform (30) mittels eines Saugkanals (33) verbunden sind, der sich entlang des gesamten Laufweges der Lackierkabinen (31a, 31b) auf der genannten Kabinenplattform (30) erstreckt.

13. System nach Patentanspruch 12, dadurch gekennzeichnet, dass der Saugkanal (33) normalerweise durch die Kabinenplattform (30) geschlossen ist und beim Vorbeilaufen der Lackierkabine (31a, 31b) durch eine Schiebvorrichtung geöffnet wird, um die Saugmittel (32) wahlweise mit der Atmosphäre der Lackierkabine (31a, 31b) in Verbindung zu setzen.

14. System nach Patentanspruch 7, dadurch gekennzeichnet, dass die beiden Lackierkabinen (31a, 31b) auf einer einzigen Strecke auf der Plattform (30) geführt sind und der Weg der Kabinen, (31a, 31b) derart weit ist, dass an einem ihrer Enden das Anhalten einer (31b) der beiden Kabinen in Ruhestellung erlaubt wird, um sie zu reinigen, während die andere Kabine (31a) sich beim Spritzschritt befindet.

15. System nach Patentanspruch 7, umfassend ein Prüfmittel (41) der Verstellgeschwindigkeit der Lackierkabinen.

16. System nach Patentanspruch 7, umfassend Prüfmittel (40) der Luftsaugstärke innerhalb der Kabine.

17. System nach Patentanspruch 1, umfassend ein Untersystem (150) zur Vorbehandlung der Fertigartikel (119), das zwischen dem geladenen Förderer (111) und der Lackiervorrichtung (116) positioniert ist.

18. Verfahren zum elektrostatischen Lackieren von metallischen Fertigartikeln unter Verwendung des Systems nach Patentanspruch 1, umfassend die folgenden Schritte:

- Aufladen der metallischen Fertigartikel (19, 119) auf Gehängen (18, 118) auf den Ladeförderern (11, 111) außerhalb und vor dem Ofen(15, 115);

- Beschichten der metallischen Fertigartikel (19, 119) mit elektrostatisch geladenem Pulver;

- Übertragen der lackierten Fertigartikel (19, 119) auf den Förderer (12, 112) zur Wärmebehandlung innerhalb des Ofens (15, 115);

- Erhitzen der metallischen Fertigartikel (19, 119) bis zur gänzlichen Polymerisation des Pulvers;

- Übertragen der polymerisierten Fertigartikel (19, 119) auf den Abladeförderer (13, 113) außerhalb und nach dem Ofen (15, 115);

- Abladen der Fertigartikel (19, 119) von den Gehängen (18, 118) am genannten Abladeförderer (13, 113); und

- Übertragen der unbeladenen Gehänge (18, 118) vom unbeladenen Förderer (13, 113)auf den zu beladenden Förderer (11, 111) automatisch mit den Mitteln des übertragenden Förderers (14,114).

19. Verfahren nach Patentanspruch 18, dadurch gekennzeichnet, dass die Gehänge (18, 118) auf den unbeladenen Förderern (13, 113) derart lange anhalten, dass die Fertigartikel (19, 119) abgekühlt werden, bevor sie vom Beschichtungssystem manuell abgeladen werden.

20. Verfahren nach Patentanspruch 18, dadurch gekennzeichnet, dass beim Beschichtungsschritt eine einzelne Lackierkabine (31a) verwendet wird, und die andere Kabine (31b) für Reinigung oder zum Farbwechsel zur Verfügung steht.

21. Verfahren nach Patentanspruch 18, dadurch gekennzeichnet, dass ein Vorbehandlungsschritt mit Wannen zwischen dem Beladungschritt und dem Pulverbeschichtungsschritt liegt.

Revendications

1. Système de peinture électrostatique pour articles manufacturés métalliques comprenant:

- un système de transport pour une pluralité de crochets de suspension (18, 118) destinés à porter des articles manufacturés métalliques (19, 119); et

- un dispositif de peinture (16, 116) pour les articles manufacturés et un four (15, 115) traversé par ledit système de transport pour le traitement des articles manufacturés (19, 119) portés par les crochets de suspension (18, 118);

caractérisé en ce que le système de transport comporte:

- un premier transporteur (11, 111), ou transporteur de chargement, pour l'accumulation des crochets de suspension (18, 118) à l'extérieur et à l'amont du four (15, 115) pour le chargement des articles manufacturés (19, 119) sur les crochets de suspension (18, 118);

- un deuxième transporteur (13, 113), ou transporteur de déchargement, pour l'accumulation des crochets de suspension (18, 118) à l'extérieur et à l'aval du four (15, 115) pour le déchargement des articles manufacturés (19, 119) des crochets de suspension (18, 118);

- un troisième transporteur (12, 112), ou transporteur de traitement par chauffage, pour l'accumulation des crochets de suspension (18, 118) à l'intérieur du four (15, 115); et

- un quatrième transporteur (14, 114), ou transporteur de transfert, reliant lesdits premier, deuxième et troisième transporteurs (11, 12, 13, 111, 112, 113) pour effectuer le transfert des crochets de suspension (18, 118) entre ceux-ci.

2. Système selon la revendication 1, caractérisé en ce que ledit quatrième transporteur (14, 114) relie le transporteur de déchargement (13, 113) au transporteur de chargement (11, 111) passant au-dessus du four (15, 115).

3. Système selon la revendication 1, caractérisé en ce que les quatre transporteurs (11, 12, 13, 14, 111, 112, 113, 114) consistent chacun en deux chaînes parallèles et ils se déplacent pas à pas à la même vitesse.

4. Système selon la revendication 1, caractérisé en ce que le four (15, 115) est du type à cloche à air chaud.

5. Système selon la revendication 4, caractérisé en ce que le four (15, 115) peut contenir plus d'un crochet de suspension (18, 118).

6. Système selon la revendication 4, caractérisé en ce que le four du type à cloche (15, 115) est muni, à sa partie inférieure, d'une ouverture (20) pour l'entrée et d'une ouverture (21) pour la sortie des crochets de suspension (18, 118).

7. Système selon la revendication 1, caractérisé en ce que le dispositif de peinture (16, 116) est traversé par ledit quatrième transporteur de transfert (14, 114) et est positionné entre le transporteur de chargement (11, 111) et le transporteur de traitement par chauffage (12, 112) dans le four (15, 115), ledit dispositif de peinture (16, 116) comprenant une plate-forme porte-cabine (30), au moins deux cabines de peinture (3 la, 31b) pour les articles manufacturés (19, 119) qui sont montées d'une façon mobile sur ladite plate-forme (30), et des moyens d'aspiration (32) reliés aux cabines de peinture (31a, 31b) pour le traitement de l'atmosphère à l'intérieur de la cabine.

8. Système selon la revendication 7, caractérisé en ce que les cabines de peinture (31a, 31b) ont des moyens pour la translation sur la plate-forme porte-cabine (30) dans une direction parallèle à une rangée de crochets de suspension (18, 118) et pour recevoir lesdits crochets de suspension (18, 118) à leur intérieur pendant le mouvement de translation.

9. Système selon la revendication 7, caractérisé en ce que chaque cabine de peinture (31a, 31 b) à son intérieur a deux distributeurs de poudres (34) rectilignes et verticaux lesquels opèrent sur les côtés opposés des articles manufacturés (19, 119) pendant l'étape de pulvérisation.

10. Système selon la revendication 9, caractérisé en ce que les deux distributeurs (34) de chaque cabine de peinture (3 la, 31b) sont inclinés selon un angle entre 0° et 60° par rapport à la direction perpendiculaire à la direction de translation de la cabine (31a, 31b).

11. Système selon la revendication 7, caractérisé en ce que les moyens d'aspiration (32) sont fixés par rapport à la plate-forme porte-cabine (30) et à l'extérieur de celle-ci.

12. Système selon la revendication 11, caractérisé en ce que les moyens d'aspiration (32) sont reliés à la plate-forme porte-cabine (30) par un canal d'aspiration (33) s'étendant le long de tout le parcours de marche des cabines de peinture (3 la, 31b) sur ladite plate-forme porte-cabine (30).

13. Système selon la revendication 12, caractérisé en ce que ledit canal d'aspiration (33) est normalement fermé sur le côté de la plate-forme porte-cabine (30) et est ouvert lors du passage de la cabine (31a, 31 b) par un dispositif coulissant pour mettre les moyens d'aspiration de l'air (32) sélectivement en communication avec l'atmosphère des cabines de peinture (31a, 31b).

14. Système selon la revendication 7, caractérisé en ce que les deux cabines de peinture (3 la, 31b) sont guidées sur un seul parcours sur la plate-forme (30) et la marche des cabines (31a, 31b) est suffisamment ample pour permettre aux extrémités l'arrêt de l'une (31b) des deux cabines en position de repos pour le nettoyage alors que l'autre cabine (3 la) est en train d'effectuer l'étape de pulvérisation.

15. Système selon la revendication 7, comprenant un moyen de contrôle (41) de la vitesse de translation des cabines de peinture.

16. Système selon la revendication 7, caractérisé en ce qu'il comporte des moyens de contrôle (40) de l'intensité d'aspiration de l'air à l'intérieur des cabines.

17. Système selon la revendication 1, caractérisé en ce qu'il comporte un sous-système (150) pour le traitement préalable des articles manufacturés (119) positionnés entre le transporteur chargé (111) et le dispositif de peinture (116).

18. Procédé pour la peinture électrostatique d'articles manufacturés métalliques en utilisant le système selon la revendication 1, comprenant les étapes suivantes:

- chargement des articles manufacturés métalliques (19, 119) sur des crochets de suspension (18, 118) sur le transporteur de chargement (11, 111) à l'extérieur et à l'amont du four (15, 115);

- pulvérisation de poudres chargées d'une façon électrostatique sur les articles manufacturés métalliques (19, 119);

- transfert des articles manufacturés peints (19, 119) sur le transporteur de traitement par chauffage (12, 112) à l'intérieur du four (15, 115);

- chauffage des articles manufacturés métalliques (19, 119) jusqu'à la polymérisation complète des poudres;

- transfert des articles manufacturés polymérisés (19, 119) sur le transporteur de déchargement (13, 113) à l'extérieur et à l'aval du four (15, 115);

- déchargement des articles manufacturés (19, 119) des crochets de suspension (18, 118) en correspondance avec ledit transporteur de déchargement (13, 113); et

- transfert des crochets de suspension déchargés (18, 118) du transporteur de déchargement (13, 113) au transporteur de chargement (11, 111) de manière automatique par le transporteur de transfert (14, 114).

19. Procédé selon la revendication 18, caractérisé en ce que les crochets de suspension (18, 118) sont arrêtés sur le transporteur de déchargement (13, 113) pendant une période suffisamment longue pour permettre le refroidissement des articles manufacturés (19, 119) avant qu'ils soient déchargés manuellement du système de peinture.

20. Procédé selon la revendication 18, caractérisé en ce que pendant l'étape de pulvérisation on utilise une seule cabine de peinture (31a), l'autre cabine (31b) étant disponible pour le nettoyage et le changement de couleur.

21. Procédé selon la revendication 18, caractérisé en ce qu'il y a une étape de prétraitement avec des cuves entre l'étape de chargement et l'étape de pulvérisation des poudres.

Drawing