DESCRIPTION

The present invention relates to an improved paint booth for applying powder paints, in particular for automated coating plants for products that use powder paint dispensing means comprising at least two guns positioned opposite one another.

As it is known, painting plants for products dedicated to the use of powder paints are provided with one or more booths in which the product is subjected to one or more series of coatings, for example one or more painting stages and/or one or more stages of baking/crosslinking with IR or UV lamps, or with hot air or induction heating.

Booths, in particular in the case of electrostatic powder painting, normally have a structure comprising a frame or framework which supports a plurality of walls positioned in such a manner that their internal surface defines a space adapted to house one or more dispensers of painting materials. Painting takes place by making the products to be treated pass through the space inside the booth so that they are exposed to dispensing of the powder by means of specific dispensing means. The dispensing means are in turn moved, for example along a vertical axis, in such a manner as to coat the whole surface of the product.

The structure of the booth, and in particular of the walls, is intended to perform two fundamental functions. A first function relates to the need to have deposition surfaces on which the powder that does not adhere to the product, or which is not drawn up by the suction system, can deposit, so as to prevent its diffusion in the surrounding environment. A second function relates to the need to remove the unused powder from the walls on which it has deposited, in order to recover and reuse said powder, and above all in order to prevent the powder from detaching from the walls and depositing on products during subsequent painting operations with different colours, contaminating their final colouring.

For this purpose, there are known in the art different solutions for cleaning the surfaces and the space inside the booths which, although allowing adequate removal and recovery of the powders, have some disadvantages.

In particular, a first solution consists simply of operations carried out manually by operators, who remove the powder deposits from the walls and from the space inside the booth. An alternative, also carried out manually, instead involves removal and replacement of the sheets at each colour change. However, it is evident that although these solutions are effective, they have a negative impact on production times and costs and oblige the operator to work in an unhealthy environment.

In order to avoid operations carried out manually, other solutions involve the use of walls made with movable sheets, generally made of deformable material such as plastic sheets which, through specific actuation systems, are moved in relation to the system for removal of the powder paint. Although this solution enables elimination of the operation carried out manually by operators and relatively effective removal of the powder, it still has some drawbacks.

For example, an operation carried out manually may still be necessary to clean the space inside the booth and the devices positioned therein, for example constituted by paint guns or dispensers in general.

In order to eliminate operations carried out manually, other solutions include the use of walls made of rigid plastic material, which can be cleaned automatically using specific motorized equipment. This system limits the possibilities of vertical extension of the booth and also has the drawback of being very costly.

A further problem, particularly in relation to a paint booth in which the dispensing means constituted by powder painting guns, is the need to support the products to be painted on specific rotating hooks so as to allow uniform painting of the products on all sides. This involves relatively long times for passage of the products inside the booth, as well as an increase in costs. It must also be underlined that solutions of this type require booths of large dimensions in order to correctly manage the operations of passage through the booth, rotation of the products and painting on all sides.

In general, booths of known type have the problem of the relatively long times required for passage of the parts through the booth and management of the operations to clean and/or empty the dispenser devices at each colour change operation.

The main aim of the present invention is to produce a paint booth, and in particular a paint booth for automated powder painting plants for products, which enables the above problems to be overcome.

Within this aim, an object of the present invention is to produce a paint booth which does not require, or in any case minimizes, cleaning operations carried out manually.

Another object of the present invention is to produce a paint booth that enables the space occupied by the booth to be minimized.

Yet another object of the present invention is to produce a paint booth that does not require complicated and bulky mechanisms for cleaning the inside of the booth.

Another object of the present invention is to produce a paint booth in which the time for passage of the parts and for management of the operations to empty the dispensers and change the colour is minimized. Another object of the present invention is to produce a paint booth that does not require complicated and costly rotation means of the parts to be painted.

Yet another object of the present invention is to produce a paint booth in which the paint dispensing devices are moved in an optimum way, in order to allow painting of parts even of considerable longitudinal dimensions, minimizing the times required for emptying and/or maintenance of these dispensing devices.

Last but not least object of the present invention is to produce a paint booth, and in particular a paint booth for automated painting plants for products which is highly reliable, relatively simple to produce and with competitive costs.

This aim, and these and other objects which shall be more apparent below, are achieved by a self-cleaning paint booth for powder coating plants for products which is characterized in that it comprises: a supporting structure, a base surface, a plurality of sheets constituting the lateral walls of said booth, said sheets forming a first and a second opening, for entry and exit of said products to and from said booth, and a third and fourth opening from which first and second means for dispensing powder paint face the inside of said booth from substantially opposite positions, said first and second means for dispensing the powder paint being respectively provided with first and second movement means, said booth also comprising first suction means positioned at said base surface, second suction means and/or third pressurizing means which extend longitudinally in height at fifth and sixth openings formed by said sheets.

In this way, due to the presence of the first suction means and of the second suction means and/or third pressurizing means, it is possible to obtain optimal containment of the powders inside the booth, as well as minimizing of the times required for the colour change operations. At the same time, the first and second means for dispensing the powder paint positioned substantially opposite each other, for example along blocks which extend vertically, ensure optimal painting of the parts without requiring more or less complicated systems for the movement thereof, such as systems based on rotating supporting hooks.

Preferably, said sheets form with the base surface a seventh opening along the perimeter of said base surface, and the first suction means are positioned at least one portion of said seventh opening.

In a particularly preferred embodiment of the paint booth according to the invention, said second suction means are positioned in substantially opposite positions relative to said base surface. In this way, it is possible to obtain optimal suction of the powders inside the booth without interfering with the path of the powders emitted by the dispensing means. It is well known that sometimes the products to be painted need to be re-touched, manually or automatically, outside the painting booth, in particular when their shape is complicated and an even coating of their surfaces would be difficult to be achieved inside the booth. Thus, in a further particular embodiment of the self-cleaning paint booth of the invention, at least one of said sheets extends outside said booth and defines at least a first space for finishing touches or pre-touches of said products. In this way it is possible to obtain a very compact structure of the whole painting station, i.e. of the station including the painting booth and the finishing touching and/or pre-touching areas.

In such a case, preferably, the self-cleaning paint booth according to the invention comprises a ninth sheet extending outside said booth and defining a first space for finishing touches of said products and a tenth sheet extending outside said booth and defining a second space for pre-touches of said products, said first and second space being positioned on opposite sides of said booth in correspondence of said first and second opening. Advantageously, suction means can be positioned in correspondence of said first and/or second space.

In a particular embodiment of the paint booth according to the invention, said sheets have a closed loop structure having an inner wall facing the inside of said booth and a portion outside said booth. Said sheets are supported by first and second support and movement means which are positioned respectively in proximity of the top and of the base of said booth and impart a rotating or reciprocating motion to said sheets. In this case, said third pressurizing means can advantageously be positioned in the cavity defined by said inner wall and by said outer portion of said sheets.

A further aspect of the booth according to the invention relates to the methods for movement of said means for dispensing the powder paint. In particular, in an embodiment of said first and second movement means, said means are adapted to move said first and second dispensing means to a first operating position and to position said first and second dispensing means in a second rest/emptying/maintenance position differing from said first operating position. In this case, said second rest/emptying/maintenance position is advantageously located in proximity of said base surface.

In a particularly preferred embodiment, said first and second dispensing means respectively comprise a plurality of guns aligned along a first and a second vertical axis, said guns being mutually spaced at a first distance when positioned in a first operating position and spaced at a second distance, less than said first distance, when positioned in a second rest/emptying/maintenance position. In this way, the emptying/maintenance operations can be carried out in proximity of the base surface, according to methods better described below. This makes it possible to minimize operations carried out manually and avoid access to workstations for maintenance of the guns located at height.

Alternatively, said first and second dispensing means respectively comprise a plurality of guns aligned in a first operating position along a first and a second horizontal axis, said guns being mutually spaced at a first distance when positioned in a first operating position and spaced at a second distance, less than said first distance, when positioned in a second rest/emptying/maintenance position.

In such a case, said first and second movement means are adapted to impart to said first and second dispensing means a rotational movement so as to align said plurality of guns along a first and a second substantially vertical axis, a second movement of translation along a substantially horizontal axis so as to withdraw said plurality of guns from said booth, and a third movement of translation so as to position said plurality of guns in said second rest/emptying/maintenance position.

Further characteristics and advantages of the present invention will be more apparent from the description of preferred, but not exclusive, embodiments of a self-cleaning paint booth according to the invention, illustrated in the accompanying drawings, in which identical reference numerals denote identical elements, without intending to limit the scope of application in any way.

In the drawings:

Figures 1-8 and 16-18 represent some embodiments of the self-cleaning paint booth according to the invention;

Figures 9-11 illustrate some details of the self-cleaning paint booth of figure 8;

Figures 12-15 represent some embodiments of the dispensing means and corresponding movement means in a self-cleaning paint booth according to the invention

With reference to the accompanying figures, the paint booth according to the invention 1, 2, 3, 4, 5, 6, 7, 8, 9, 90 and 100 comprises a supporting structure 10, for example constituted by a supporting framework.

The booth 1, 2, 3, 4, 5, 6, 7, 8, 9, 90 and 100 also comprises a base surface 20, a plurality of sheets 31, 32, 33, 34, 35, 36, 37, and 38 which constituted the lateral walls of said booth 1, 2, 3, 4, 5, 6, 7, 8, 9, 90 and 100. In particular, said sheets forming a first 41 and a second 42 opening, for entry and exit of said products to and from said booth, and a third 43 and a fourth 44 opening from which first 51 and second 52 means for dispensing powder paint face the inside of said booth 1, 2, 3, 4, 5, 6, 7, 8, 9, 90 and 100. The means for dispensing powder paint 51, 52 can, for example, be constituted by powder paint guns or by powder paint blades. Preferably, said first and second means for dispensing the powder paint 51, 52 are each constituted by a plurality of powder paint guns 510 and 520 arranged superimposed and aligned vertically, on at least one row per side. Alternatively, as represented in figure 18, said first and second means for dispensing the powder paint 51, 52 are each constituted by a plurality of powder paint guns horizontally aligned in a row, on at least one row per side

One of the peculiar characteristics of the booth 1, 2, 3, 4, 5, 6, 7, 8, 9, 90 and 100 according to the invention is given by the fact that said means for dispensing the powder paint 51, 52 face the inside of said booth from substantially opposite positions. For the purposes of the present invention, the characteristic that said means for dispensing the powder paint 51, 52 face the inside of said booth from substantially opposite positions should be intended to refer to a situation in which said dispenser means emit powders in opposite directions along two substantially parallel axes. Preferably, the emission of powder by the opposite dispensing means takes place along a same axis so that the jets of powder "collide" at the part to be painted.

The first 51 and second 52 means for dispensing the powder paint are advantageously provided respectively with first 511 and second 521 movement means, adapted to impart a suitable movement to said dispensing means according to methods better specified below.

Another of the peculiar characteristics of the booth 1, 2, 3, 4, 5, 6, 7, 8, 9, 90 and 100 according to the invention consists in the fact that said booth is provided with first suction means 61 positioned at said base surface 20, and second suction means 62 and/or third pressurizing means 63 which extend vertically at fifth 45 and sixth 46 openings formed by said sheets.

For example, the second suction means 62 can be constituted by suction collectors positioned vertically at the openings 45 and 46, or at one of the other openings between the lateral sheets. The suction collectors 62 have a slot that extends in vertical direction in proximity of the internal surface of the sheets 31, 32, 33 and 34 and contribute to the cleaning of these sheets and of the space inside the booth. Advantageously, the suction collectors 62 are suitably connected to cyclones 621 for recovery of the powder.

In the same way, the third pressurizing means 63, when present, can also be constituted by pressurizing collectors positioned vertically with slots which extend in a vertical direction. Both in the case of suction and pressurizing, these slots are preferably produced in such a manner that their width is progressively decreasing along the extension of the collector so as to compensate the losses of load and ensure a constant air flow along the whole height of the collector. The pressurizing collectors 63 are appropriately connected to forced air generation means (compressors / fans) which ensure an adequate supply of air to these pressurizing collectors. For example, the pressurizing collectors 63 can be supplied by a filter box located on the roof of the booth. This box can advantageously be supplied with air from the deduster normally present in systems of this type or by a separate fan. Equipment for conditioning and/or dehumidifying the air supply can also be provided according to need.

In this way, due to the presence of the second suction means 62 and/or third pressurizing means 63, air curtains are created with a strength sufficiently low to ensure they do not to disturb the internal flow of powders (besides preventing oscillation of the parts or removal of the powders from the surface thereof) but at the same time sufficiently high to prevent the powders from escaping to the outside.

Moreover, the total balance of air sucked in/issued by said first suction means 61, second suction means 62 and/or third pressurizing means 63, and the air supplied through said first and second dispensing means of the powder paint 51, 52, is such as to determine an overall condition of slight vacuum pressure inside the booth 1, 2, 3, 4, 5, 6, 7, 8, 9, 90 and 100, in such a manner as to prevent powder from escaping from the booth.

The openings 41, 42, 43, 44, 45, and 46 can be produced by several sheets appropriately spaced from one another and consequently will extend for the whole height of the booth 1, 2, 3, 4, 5, 6, 7, 8, 9, 90 and 100. Alternatively, said openings can be constituted by cuts appropriately produced in the lateral sheets; in this case these openings extend only for a portion of the height of the booth 1, 2, 3, 4, 5, 6, 7, 8, 9, 90 and 100.

Preferably, said sheets 31, 32, 33, 34, 35, 36, 37, and 38 form with the base surface 20 a seventh opening 47 along the perimeter of said base surface 20. In this case, said first suction means 61 are positioned at least one portion of said seventh opening 47. In this way, said first suction means 61 act simultaneously both on the base surface 20 and on the lateral sheets 31, 32, 33, 34, 35, 36, 37, and 38, contributing to and ensuring cleaning thereof.

Advantageously, suction collectors which almost "contain" the lower end of the lateral sheets can be positioned at said seventh opening. The booth according to the invention is therefore preferably provided with a perimeter suction system at the base surface, which considerably improves the performance of the booth. In practice, perimeter suction rather than, for example, central suction, enables the powder issued to "linger" as much as possible in the vicinity of the product. The base surface 20 can be constituted by a fixed structure, or by a horizontal belt. In any case, cleaning thereof is ensured by the position of the first suction means 61. However, further cleaning means, such as suction and/or blowing and/or scraping means, could be provided both on the base surface 20 and on the laterals sheets 31, 32, 33, 34, 35, 36, 37, and 38.

In a preferred embodiment of the paint booth according to the invention, said second suction means 62 are positioned substantially opposite relative to said base surface. In other words, as shown in Figs 3-8 and 16-18, the suction means 62 are positioned in such a manner as to face the inside of the booth from opposite positions, maximizing the efficiency of suction and minimizing interference of the air flows generated thereby with the flow of powder issued by the first and second dispensing means 51 and 52.

According to a particular embodiment of the booth according to the invention, said third pressurizing means 63 are positioned at said first 41 and second 42 openings, i.e. at the positions for entry and exit of the parts to be painted in the booth.

In a further particular embodiment of the booth according to the invention, said sheets 31, 32, 33, 34, 35, 36, 37, and 38 have a closed loop structure having an inner wall facing the inside of said booth and a portion outside said booth. The sheets 31, 32, 33, 34, 35, 36, 37, and 38 are supported by first 310 and second 230 support and movement means respectively positioned in proximity of the top and of the base of said booth. Said support and movement means 310 and 320 are, for example, constituted by rollers that impart a reciprocating or continuous rotation movement to said sheets. In this embodiment, the pressurizing means 63 are positioned in the cavity defined by said inner wall and by said outer portion of said sheets.

With reference to Figs. 6-8, in a particular embodiment of the paint booth 6, 7, 8 according the invention said base surface 20 is substantially quadrangular with a first 21, a second 22, a third 23 and a fourth 24 side, said sheets comprising a first 31 and a second 32 sheet arranged on said first side 21 and forming said first opening 41, a third 33 and a fourth 34 sheet arranged on said second side 22, opposite and substantially parallel to said first side 21, and forming said second opening 42, a fifth 35 and a sixth 36 sheet arranged on said third side 23, substantially perpendicular to said first 21 and second 22 side, and forming said third opening 43, a seventh 37 and an eighth 38 sheet, arranged on said fourth side 24, opposite and substantially parallel to said third side 23, and forming said fourth opening 44.

The products to be treated enter the space inside the booth, normally hanging from an overhead conveyor, and are subjected for the entire length thereof to the painting operation through the dispensing means 51 and 52. This is made possible by the fact that the dispensing means 51 and 52 move vertically and with reciprocating motion during passage of the products inside the booth. The dispensing means 51 and 52 are positioned substantially symmetrically with respect to the transverse axis of the space inside the booth and their travel is advantageously adjusted so that the whole surface of the product is treated.

In this way, it is possible to obtain a booth with limited dimensions and which simultaneously allows easy containment of the powders therein, fast passage of the parts and easy cleaning during the colour change operations.

A particular embodiment of the self-cleaning paint booth according to the invention, illustrated in figures 16 and 17, is particularly suitable when the products to be painted need to be re-touched outside the paint booth.

In such a case, in the self-cleaning paint booth 9 and 90 at least one of said sheets extends outside said booth and defines at least a first space 151 for finishing touches or pre- touches of said products. As shown in Figs 16 and 17, preferably, the self-cleaning paint booth 9 and 90, comprises a ninth sheet 39 extending outside said booth and defining a first space 151 for finishing touches of said products and a tenth sheet 390 extending outside said booth and defining a second space 152 for pre-touches of said products, said first 151 and second 152 space being positioned on opposite sides of said booth in correspondence of said first 41 and second 42 opening.

As shown in figure 17, the self-cleaning paint booth 90 may also comprise suction means 620 positioned in correspondence of said first 151 and/or second 152 space. Further sheets 391 and 392 may also be present to help containment of the coating powder in said 151 and/or second 152 space.

In a further aspect thereof, the present invention also relates to a suitable configuration of the means 51 and 52 for dispensing powder paint and to appropriate movement thereof by means of the respective movement means 511 and 521.

In particular, said first 511 and second 521 movement means are adapted to move said first 51 and second 52 dispensing means to a first operating position and to position said first 51 and second 52 dispensing means in a second rest/emptying/maintenance position differing from said first operating position.

Said movement means can be activated by a single actuator, for example a motor, or can be provided with independent actuators, for each block or for each gun.

In other words, the first 511 and second 521 movement means allow the reciprocating movement in vertical direction of the dispensing means 51 and 52 along a predetermined operating path, for example by means of a reciprocator. At the end of the operations, the dispensing means 51 and 52 of each of the two groups are returned to a rest position by means of said first and second movement means 511 and 522, said rest position being located in proximity of said base surface 20. Contrary to prior art booths, in which the maintenance and/or emptying and/or colour change operations are normally carried out in the operating position, in the booth according to the invention these operations are conducted in proximity of the base surface, thus reducing the times for the operation and eliminating the need for superstructures to enable operators to access the operating position of the paint dispensing means at height, especially when these are positioned at greater heights to those accessible to an operator standing on the ground.

In another greatly preferred embodiment of the invention, said first and second dispensing means 51 and 52 respectively comprise a plurality of guns aligned along a first and a second vertical axis, said guns being spaced from one another at a first distance when positioned in a first operating position and spaced at a second distance, less than said first distance, when positioned in a second rest/emptying/maintenance position.

In practice, in the operating position, the guns are arranged along one or more vertical blocks that extend for the whole height of the part to be painted and are spaced from one another and moved in such a manner as to cover at least a portion of the length of the part to be painted. At the end of the operations, the movement means carry the guns in proximity of the base surface "lowering them" and superimposing them in proximity to one another. At this point it is possible to proceed, for example, with the operations to empty and clean them externally. This last operation can, for example, be carried out using suitable ring blowers or air blades positioned around the guns, which enable powder to be removed from the outer surface of the guns.

In a particular embodiment of the booth according to the invention the suction means of the lateral sheets are provided with one or more openings controlled, for example, by appropriate valves, positioned under the base surface of the booth. The dispensing means, during the colour change, are positioned at said openings, optionally being inserted more or less completely, to enable emptying and cleaning thereof. In such a case, ring blowers or air blades positioned around the guns are no longer necessary, provided that the suction power is sufficient also for cleaning the guns.

Advantageously, said first and second movement means 511 and 521 are adapted to impart to said dispensing means 51, 52 a first movement of translation along a substantially vertical axis, a second movement of translation along a substantially horizontal axis, and optionally a third movement of rotation relative to said first substantially vertical axis.

The first movement of translation enables, for example, movement during the painting operation and the operation to lower the guns; the second translation movement enables the guns to be moved forward or withdrawn in relation to the inside of the booth, for example during the emptying and cleaning operations; the third rotation movement enables the dispensing angle to be varied as a function of the requirements and of the geometry of the part to be painted.

A typical colour change operation can therefore be carried out by withdrawing the guns from the booth and lowering them in proximity of the base surface of the booth. Emptying can be carried out in a specific suction collector or, preferably, in one of the suction means arranged at the base surface, for example in the suction means of the lateral sheets provided with openings controlled by means of suitable valves positioned under the base surface of the booth, by moving the guns forward into said valves. After emptying the guns are withdrawn from the valve, or in any case from the suction means, repositioned at height and moved forward in the booth.

It is also possible to provide several vertical blocks of guns on the same side. In this case, the guns of one block can be arranged aligned relative to the guns of the adjacent block, as shown in figure 13, or staggered relative thereto, as shown in figure 14 and 15. In this latter case, a further horizontal translation movement of the guns of the two adjacent blocks can be provided, so that they are superimposed along a same vertical axis, to form a single block with double the number of guns relative to the original configuration.

In an alternative embodiment, shown in figure 18, said first 51 and second 52 dispensing means respectively comprise a plurality of guns aligned in a first operating position along a first and a second horizontal axis, said guns being mutually spaced at a first distance when positioned in a first operating position and spaced at a second distance, less than said first distance, when positioned in a second rest/emptying/maintenance position. In particular, the first and second movement means can be advantageously adapted to impart to said first and second dispensing means a rotational movement so as to align said plurality of guns along a first and a second substantially vertical axis, as illustrated by the thick arrows in figure 18. The first and second movement means can then impart a second movement of translation along a substantially horizontal axis so as to withdraw said plurality of guns from said booth, and a third movement of translation so as to position said plurality of guns in said second rest/emptying/maintenance position.

The embodiment of figure 18 has been illustrated with reference to the lay out of the paint booth of figure 7. It is however possible to use such arrangement of the dispensing means and movement means also in other paint booth configurations.

In general, the positioning of the dispensing means, as well as the path of the products inside the paint booth can be adapted according to the needs.

It has been seen how the paint booth according to the invention makes it possible to fully achieve the set aim and objects. Appropriate positioning of the dispensing means, opposite one another, allows optimal painting of the products, reducing the space normally required by conventional booths and decreasing the time for passage of the parts in the booth.

Simultaneously, positioning of the sheets and of the openings formed by these sheets, combined with the presence and appropriate positioning of suction and/or pressurizing means, allows effective removal of the residues of painting material from the sheets and from the space inside the booth.

Another important result achieved with the booth of the present invention is optimization of the movement means of the means for dispensing the powder paint. Unlike booths of known type which required structures to enable access to the work station of the dispensing means at height when these cannot be reached by an operator standing on the ground, the booth according to the invention allows all maintenance, emptying and colour change operations to be carried out in proximity of the base surface. This enables a reduction in the mechanical complexity of the booth and a decrease in the installation and maintenance costs of the booth itself and of the plant associated therewith.

In general, painting booths provided with self-cleaning sheets on all perimetral and bottom walls are not known. Moreover, booths with sheets, provided with dispensing means arranged aligned on one or more opposite vertical blocks are not currently known.

The booth according to the present invention may advantageously be used in painting plants for products. Painting plants for products, and in particular automated painting plants comprising one or more booths according to the description above, form a further aspect of the present invention.

On the basis of the foregoing description, other characteristics, modifications or improvements are possible and evident to the average person skilled in the art. These characteristics, modifications and improvements must therefore be considered part of the present invention. In practice, the materials used, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.