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Title:
POWDER PAINTING STATION WITH AUTOMATIC CLEANING SYSTEM
Document Type and Number:
WIPO Patent Application WO/2021/074805
Kind Code:
A1
Abstract:
A station for painting manufactured articles by powder paint comprises a conveyance line (12) for conveying the manufactured articles (11), an apparatus (14) for applying the paint to the manufactured articles (11), arranged on one side with respect to the conveyance line (12) and provided with guns (15) for dispensing paint towards the manufactured articles (11), and a system (17) for suction of the excess paint, arranged on the other side with respect to the conveyance line (12). The system (17) for suction of excess powder paint comprises a pair of vertical axis counterrotating rollers (18, 18'), positioned close to the conveyance line (12) and mutually spaced transversally with respect to the spraying direction to individuate therebetween a passage (19) for the powder paint that passed beyond the conveyance line (12), a suction chamber (20) downstream of the rollers (18, 18'), extending vertically with a lateral wall (21) provided with a vertical inlet opening (22) faced toward the passage (19) between the rollers (18, 18'), and a pair of connecting walls (23, 23') provided on two sides of said passage (19) between the latter and the inlet opening (22) to realize continuity and closure of the passage (19) up to the suction chamber (20), said connecting walls (23, 23') being provided with a free end (25, 25') resting against the outer surface of the rollers (18, 18').

Inventors:
BORTOLATO GIOVANNI (IT)
RONCORONI PAOLO (IT)
Application Number:
PCT/IB2020/059634
Publication Date:
April 22, 2021
Filing Date:
October 14, 2020
Export Citation:
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Assignee:
S E F ITALIA S R L (IT)
International Classes:
B05B16/40; B05B13/04; B05B14/41; B05B14/44; B05B14/48; B05B16/00
Domestic Patent References:
WO2017006220A12017-01-12
Foreign References:
US20070062444A12007-03-22
DE9320763U11995-01-19
CN201586606U2010-09-22
FR2427145A11979-12-28
Attorney, Agent or Firm:
LOCATELLI, Massimo (IT)
Download PDF:
Claims:
CLAIMS

1. Painting station for painting manufactured articles by powder paint, comprising a conveyance line (12) for conveying the manufactured articles (11), an apparatus

(14) for applying powder paint on the manufactured ar ticles (11), arranged on one side with respect to the conveyance line (12) and provided with one or more guns

(15) for dispensing the powder paint along a spraying direction toward the manufactured articles (11) present on the conveyance line (12), and a system (17) for suc tion of excess powder paint, arranged on the other side with respect to the conveyance line (12), characterized in that the system (17) for suction of excess powder paint comprises a pair of vertical axis counter rotating cylindrical rollers (18, 18'), positioned close to the conveyance line (12) and mutually spaced along a transversal direction with respect to said spraying direction to individuate therebetween a pas sage (19) for a flow of powder paint that passed beyond the conveyance line (12), a suction chamber (20) placed downstream of the rollers (18, 18') relative to said spraying direction, said chamber extending vertically and having a lateral wall (21) provided with a vertical inlet opening (22) faced toward said passage (19) be tween the rollers (18, 18'), and a pair of connecting walls (23, 23') respectively provided on two sides of said passage (19) between the latter and said inlet opening (22) to realize continuity and side closure of the passage (19) up to the suction chamber (20), said connecting walls (23, 23') being provided with a free end (25, 25') resting against the outer surface of the rollers (18, 18').

2. Painting station for painting manufactured articles by powder paint according to claim 1, characterized in that the other end (24, 24') of said connecting walls

(23, 23') is constrained to the lateral wall (21) of the suction chamber (20), at the edges of the inlet opening (22).

3. Painting station for painting manufactured articles by powder paint according to claim 1, characterized in that the connecting walls (23, 23') are made of elasto- meric material or of flexible plastic material and at least their portions close to the free end (25, 25') are preloaded in the direction of the respective roller 18, 18'), so as to maintain a predetermined pressure against the outer surface of the same rollers. 4. Painting station for painting manufactured articles by powder paint according to claim 3, characterized in that said free ends (25, 25') of the connecting walls

(23, 23') act, during the rotation of the rollers (18,

18'), as cleaning blades for removing the powder paint deposited on the surface of the rollers.

5. Painting station for painting manufactured articles by powder paint according to claim 1, characterized in that the rollers (18, 18') extend vertically over a height substantially equal to the vertical extension of the manufactured articles (11), the suction chamber (20) extends, with its own side wall (21), vertically over a height substantially equal to the vertical ex tension of the rollers (18, 18') and the inlet opening

(22) of the suction chamber (20) extends over the en- tire height of the chamber itself.

6. Painting station for painting manufactured articles by powder paint according to claim 1, characterized in that the suction chamber (20) is connected to one or more suction ducts (28).

7. Painting station for painting manufactured articles by powder paint according to claim 1, characterized in that the rollers (18, 18') are internally hollow, with a side wall (30) made of plastic and supported by a metal structure (31).

8. Painting station for painting manufactured articles by powder paint according to claim 7, characterized in that the supporting structure of the rollers (18, 18') centrally comprises a metal tube (32) coaxial with the axis of rotation of the roller.

9. Painting station for painting manufactured articles by powder paint according to claim 8, characterized in that the supporting structure of the rollers (18, 18') further comprises a pair of upper and lower closing walls (33, 34), centrally provided with respective bushings (35, 36) able to allow the rotation of the roller.

10. Painting station for painting manufactured articles by powder paint according to claim 7, characterized in that the rollers (18, 18') comprise a system (40) for humidifying the inner surface of their side wall (30).

11. Painting station for painting manufactured articles by powder paint according to claims 8 and 10, charac terized in that said humidification system (40) com prises spraying nozzles (41) present in the wall of the central metal tube (32) for spraying liquid from the inside of the tube towards the inner surface of the side wall (30) of the roller.

12. Painting station for painting manufactured articles by powder paint according to claim 1, characterized in that said one or more guns (15) for dispensing the pow der paint is mounted on a structure (16) vertically movable along the vertical extension of the manufac tured articles (11). 13. Painting station for painting manufactured articles by powder paint according to claim 1, characterized in that the manufactured articles (11) are supported on the conveyance line (12) in a vertical position.

Description:
POWDER PAINTING STATION WITH AUTOMATIC CLEANING SYSTEM The present invention relates to a painting station for painting manufactured articles, for example metal or non-metal profiles, by means of powder paints.

In the prior art, painting stations are normally used arranged inside a painting booth, or in any case pro tected by suitable covering walls adapted to prevent the dispersion to the external environment of paint powders in excess with respect to those actually used to cover the surface of the manufactured articles to be painted.

In fact, excess powders are usually recovered to be re used in further painting steps with the same colour.

Of course, these types of painting stations with booth or other protective structures are complex and expen sive and, in any case, do not allow a quick and easy colour change, since various components of the station remain partially covered with the colour powder used until then and therefore they need to be cleaned (usu ally manually) before the replacement with the new col our to be applied.

Various solutions have been proposed to limit the dis persion of powders and facilitate the recovery thereof. For example, booths equipped with a cleaning system us ing moist sponges, mounted on a frame having the same profile as the booth and shifted from one side to the other, have been proposed, as well as axially rotating cylindrical booths equipped with cleaning blades, cy lindrical booths with vertical axis equipped with com pressed air nozzles for cleaning their bottom, booths with vibrating bottom to facilitate the removal of ex cess powders deposited, booths with movable suction belt, etc.

However, as mentioned, these systems are complex, ex pensive and bulky. In addition, they generally always require manual cleaning to completely eliminate the traces of the colour used. As a result, the average time required to carry out a colour change in the painting station is hardly less than 10-20 minutes, with a consequent overall slowdown in the production cycles. Furthermore, it must be considered that the regulations concerning health and environmental hygiene are in creasingly restrictive and aim to avoid manual cleaning operations in the presence of powders and chemicals.

The general object of the present invention is to over- come the drawbacks mentioned above by providing a painting station for painting manufactured articles by powder paint, which does not require a painting booth with the relative structure which is generally complex, expensive and bulky and which also requires appropriate design solutions to prevent the discharge of powders at the inlet and outlet passages of the workpieces.

A further object of the present invention is to almost completely avoid the need for manual cleaning opera tions of the painting station from the powder paint previously used, when a colour change is required.

A further object of the present invention is to avoid dispersion of the powder paints in the environment, which normally occur during cleaning operations.

A further object of the present invention is to allow a drastic reduction in time necessary to carry out the colour change in the system.

A further object of the present invention is to obtain a considerable construction simplification of the painting station, also minimizing maintenance costs.

In view of said objects, it has been thought of realis ing, according to the invention, a painting station for painting manufactured articles by powder paint, com prising a conveyance line for conveying the manufac tured articles, an apparatus for applying powder paint on the manufactured articles, arranged on one side with respect to the conveyance line and provided with one or more guns for dispensing the powder paint along a spraying direction toward the manufactured articles present on the conveyance line, and a system for suc tion of excess powder paint, arranged on the other side with respect to the conveyance line, characterized in that the system for suction of excess powder paint com prises a pair of vertical axis counter-rotating cylin drical rollers, positioned close to the conveyance line and mutually spaced along a transversal direction with respect to said spraying direction to individuate therebetween a passage for a flow of powder paint that passed beyond the conveyance line, a suction chamber placed downstream of the rollers relative to said spraying direction, said chamber extending vertically and having a lateral wall provided with a vertical in let opening faced toward said passage between the roll ers, and a pair of connecting walls respectively pro vided on two sides of said passage between the latter and said inlet opening to realize continuity and side closure of the passage up to the suction chamber, said connecting walls being provided with a free end resting against the outer surface of the rollers.

To clarify the explanation of the innovative principles of the present invention and the advantages thereof with respect to the prior art, one possible illustra tive embodiment applying such principles will be de scribed below, with the aid of the attached drawings. In the drawings:

Fig.l represents a schematic plan view of a painting station according to the invention.

Fig.2 represents an elevation view of the painting sta tion, taken along the section II-II of Fig.l.

Fig.3 represents a section view of one of the rotating cylinders of the painting station.

With reference to the figures, Fig.l schematically shows, in plan, a painting station 10 adapted to be used to paint, by powder paints, manufactured articles 11 which are conveyed to the painting station 10 along a conveyance line 12 advancing in the direction of the arrow 13. For example, the conveyance line 12 can con sist of an overhead conveyor with suitable hooks for hanging the manufactured articles to be painted.

The manufactured articles to be painted can typically be metal or non-metal profiles, the use of which is well known to the person skilled in the art, for exam ple in the construction sector, and which therefore are not further described here in detail.

Advantageously, the manufactured items 11 can be con veyed along the conveyance line 12 suitably supported in a vertical position, as schematized in Fig.l. Of course, with suitable adaptations easily imaginable by those skilled in the art, a conveyance configuration in a horizontal position can also be provided, remaining however within the scope of the present invention.

On one side with respect to the conveyance line 12 there is an apparatus 14 for applying the electrostati cally charged powder paint to the manufactured articles 11. Said apparatus can of course be chosen of the most suitable type according to the characteristics and di- mensions of the pieces to be painted, as well as the painting methods envisaged, as easily imaginable by those skilled in the art.

However, substantially, the apparatus 14 comprises one or more guns 15 for dispensing the powder paint toward the manufactured articles 11, the guns 15 being advan tageously mounted on a structure 16 vertically movable along the vertical extension of the manufactured arti cles 11, so as to obtain maximum coverage of the pieces to be painted. If necessary, the paint dispensing guns 15 may also have rotational mobility, for directing the powder paint in directions inclined with respect to the conveyance line 12.

On the other side with respect to the conveyance line 12 there is a system 17 for suction of the excess pow- der paint, i.e. the paint that passed beyond the verti cal plane identified by the conveyance line 12 without depositing itself on the surface of the manufactured articles 11.

In this context, it may be appropriate to define as a "paint spraying direction" a generic direction which, starting from said one or more dispensing guns 15, crosses the vertical plane identified by the conveyance line 12 of the manufactured articles to be painted, continuing towards the paint suction system 17. The suction system 17 comprises a pair of vertical axis counter-rotating cylindrical rollers 18, 18', posi tioned close to the conveyance line 12 and mutually spaced along a transversal direction with respect to said paint spraying direction to individuate there between a passage 19 for the flow of powder paint that passed beyond the vertical plane identified by convey ance line 12.

Preferably, the rollers 18, 18' extend vertically over a height substantially equal to the vertical extension of the manufactured articles 11.

The suction system 17 further comprises a suction cham ber 20 placed downstream of the rollers 18, 18' rela tive to the paint spraying direction. Advantageously, said suction chamber 20 extends, with its own lateral wall 21, vertically over a height substantially equal to the vertical extension of the rollers 18, 18' and is provided, in said lateral wall 21, with a vertical in let opening 22 faced toward the aforesaid passage 19 between the rollers 18, 18' and extending over the en tire height of the chamber itself.

Between the passage 19 identified by the rollers 18, 18' and the inlet opening 22 of the suction chamber 20, respective connecting walls 23, 23' are arranged on the two sides of the passage itself and along its entire height, adapted to ensure side closure and continuity of the passage 19 up to the aforesaid inlet opening 22 of the suction chamber 20.

It has been found particularly advantageous, in order to achieve the set aims, that the connecting walls 23, 23' are constrained with a first end thereof 24, 24' to the lateral wall 21 of the suction chamber 20, at the edges of the inlet opening 22, while the second free end 25, 25' of said connecting walls 23, 23' rests against the outer surface of the rollers 18, 18'. Preferably, the connecting walls 23, 23' are made of elastomeric material or of flexible plastic material and at least their portions close to the free end 25, 25' are preloaded in the direction of the respective roller 18, 18', so as to maintain a predetermined pres sure against the outer surface of the same rollers.

In this way, when the rollers rotate during the opera tion of the system (which takes place in the direction of the arrows 26, 26' shown in Fig.l), the aforesaid free ends 25, 25' of the connecting walls 23, 23' act as cleaning blades, removing the excess powder paint from the surface of the rollers that deposited on them following the painting of the manufactured articles along the conveyance line 12 and conveying it inside the suction chamber 20, in the direction of the arrow 27.

The suction chamber 20 is in turn connected to one or more suction ducts 28 connected to a suction pump, ar ranged in a suitable position further downstream (in the direction of the arrow 29 in Fig.l) and therefore not visible in the attached drawings.

As the person skilled in the art can easily imagine, the choice of the number and the position of the suc tion ducts 28 along the suction chamber 20 can be made according to the quantity of air to be sucked, its speed and, in particular, so as to maintain the speed of the air flow as uniform as possible along the entire height of the opening 22. By way of example, it can be thought of maintaining, near the passage between the connecting walls 23, 23', a speed of the air flow in the order of 20 m/s, with a flow rate of about 1,000 m 3 /h. Fig.2 shows, by way of an example, three suction ducts 28 distributed along the height of the suction chamber 20.

It is apparent from the description made herein that the suction system 17 allows to channel all the excess powder paint (i.e. the paint that passed beyond the vertical plane identified by the conveyance line 12 without depositing on the surface of the manufactured articles 11), and in particular both the one which de- posited on the outer surface of the rollers 18, 18' and the one which has possibly remained suspended in the interspace 19 between the rollers, towards the passage between the connecting walls 23, 23' and then inside the suction chamber 20, through the inlet opening 22, to be then moved away along the suction ducts 28 and subsequently recovered and/or disposed of. All this can be done with no need for a painting booth or other sep aration structures between the painting station and the external environment. However, it has been found particularly advantageous, in terms of cleaning efficiency, to make sure that as much of the excess powder paint as possible is made to adhere to the outer surfaces of the two counter rotating cylindrical rollers 18, 18', so as to be easi- ly and effectively removed by the cleaning blades con stituted by the free ends 25, 25' of the connecting walls 23, 23' and conveyed into the suction chamber 20. To achieve adequate adhesion of the powder paint to the outer surface of the rollers 18, 18', the latter (which, from a structural and dimensional point of view, can be considered substantially identical to each other) are preferably made internally hollow, with a side wall 30 made of plastic supported by an earthed metal structure 31, so as to avoid the possible genera tion of electrostatic discharges.

As better visible in Fig.3, according to a preferred embodiment, the supporting structure of the rollers 18, 18' can centrally comprise a metal tube 32 coaxial with the axis of rotation of the roller and a pair of upper and lower closing walls 33, 34 centrally provided with respective bushings 35, 36 able to allow the rotation of the roller itself with respect to an external sup port frame, upon actuation by a motor 37 and by a transmission 38 advantageously arranged under a base 39 as schematically illustrated in Fig.2.

To further improve the adhesion of the powder paint to the outer surface of the rollers 18, 18', a system 40 for humidifying the inner surface of the wall 30 of the roller can also be provided, so as to make the wall it self sufficiently conductive and to favour the adhesion of the powder paint thereto. The humidification can ad vantageously be obtained by spraying or nebulizing wa ter or other liquid having similar characteristics of electrical conductivity.

According to a preferred embodiment, the spraying of the liquid towards the inner surface of the rotating roller can take place, as schematically shown in Fig. 3, through suitable spraying nozzles 41 present in the wall of the central metal tube 32, inside which the liquid itself is supplied from a suitable tank 42.

It is clear at this point how a painting station ac cording to the invention can allow to overcome the drawbacks of the systems of the prior art and therefore achieve the predetermined purposes. In particular, a great simplification of the painting station can be obtained, with no need for a special booth or other structures to protect the external envi ronment. Furthermore, it is possible, with no need for manual intervention, to quickly and easily clean the station itself from the previously used powder paint, when a colour change is required.

A possible cycle for cleaning the station from the pre- viously used powder paint will be briefly described by way of an example.

Cleaning, of course, must be carried out in the absence of manufactured articles 11 along the conveyance line 12. From the so-called "Powder Centre", that is the station for managing the various powders to be used from time to time in the painting system, clean air is sent in side the supply ducts to the guns 15, so as to inter nally clean the dispensing apparatus by pushing the residues of the previously used powder paint towards the suction system 17, which obviously must be specifi cally activated in the same operating modes envisaged during the painting step.

To completely eliminate the residues of the previous powder paint from the spraying area, a mechanical cleaning device (consisting, for example, of a sliding sleeve) of the external area of the nozzles of the dis pensing guns 15 can be possibly activated.

At this point, the system is ready for loading, in the "Powder Centre", the new powder paint to be used on the new incoming manufactured articles.

Thanks to a painting station according to the inven- tion, the duration of the cleaning cycle required to carry out a colour change can also be reduced to just 3-5 minutes.

Clearly, the description made above of an embodiment applying the innovative principles of the present in vention is given by way of an illustrative example of such innovative principles and must not, therefore, be taken to limit the scope of the patent claimed herein. For example, if deemed operationally preferable, the paint dispensing guns 15 could be supported by a multi axis robot capable of optimizing the positioning of the dispensers and the paint spraying direction relative to the manufactured articles 11.

Finally, various design solutions easily imaginable by the skilled person can be provided to carry out a com plete painting of the manufactured articles on both their faces.

For example, it is possible to choose to position two painting stations, arranged in series along the convey- ance line 12, in an opposed way (each with its own ap paratus 14 for applying the powder paint and its own suction system 17, but oriented in an opposed way with respect to the conveyance line 12), or it can be chosen to provide the conveyance line 12 with rotatable hooks for the manufactured articles, so as to rotate the lat- ter (keeping them in position in the painting area, or by making two runs in opposite directions after having rotated them downstream of the painting area).




 
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