Cleaning station for cleaning the spraying guns in a spray booth, and method

Abstract

A spray booth for spraying pieces to be painted with a painting product includes a system that conveys the pieces to be painted inside the booth, a supplying circuit that supplies a painting product or solvent to painting tools, a plenum, a mobile wall providing access to the inside of the spray booth, optionally a reading system for the pieces to be painted, optionally a filtering system, a plurality of spraying tools that include one or more a spray guns each placed on an independent arm moving on a plane and optionally in a vertical direction, one or more cleaning stations, placed in correspondence of the mobile wall and provided with a drawer that is mobile between rest and a cleaning positions and that includes a painting product or solvent draining tube having a mouth, a slot for supplying compressed air, and a brush for brushing the spray guns.

Claims

1. A spray booth for spraying pieces to be painted with a painting product, comprising: a system configured to convey said pieces to be painted inside side spray booth; a supply circuit configured to supply a painting product or solvent to painting tools; a plenum; a mobile wall allowing to access an inside of said spray booth; optionally a reading system for the pieces to be painted; optionally a filtering system; a plurality of spraying tools comprising one or more spray guns, each of the spraying tools being placed on an independent arm moving on a plane and optionally in a vertical direction; and one or more cleaning stations placed in correspondence of said mobile wall, said one or more cleaning stations being each provided with a drawer that is mobile between a rest position and a cleaning position, said drawer comprising: a draining tube of said painting product or solvent provided with a mouth; a slot configured to supply compressed air; and a brush for brushing said one or more spray guns.

2. The spray booth according to claim 1, wherein said spraying tools further comprise a draining gun.

3. The spray booth according to claim 1, wherein said brush is at least partially immersed in a tank containing solvent, by which said brush is wetted, said solvent being supplied by the supply circuit of the painting product or solvent; or wherein said brush performs a dry brushing of said one or more spray guns.

4. The spray booth according to claim 1, wherein said one or more cleaning stations are placed on a same side as the spray booth on which a suction tower is arranged, or alternatively said one or more cleaning stations are arranged on an operator's side.

5. The spray booth according to claim 1, wherein there are four spraying tools and four cleaning stations.

6. A method of cleaning spraying tools of a spray booth according to claim 1, the method comprising the following steps: a. Inserting the drawer of one of the one or more cleaning station inside the spray booth; b. Inserting the spraying tool provided with one or more spray guns inside said drawer; c. Draining the supply circuit which channels a first painting product by positioning each spray gun in front of the mouth of the draining tube; d. Optionally, supplying a solvent to one or more spraying guns, and optionally positioning each spray gun in front of the mouth of the draining tube; e. Externally brushing said one or more spray guns by dry brushing or wet brushing with said brush; f. Externally blowing the spraying tool with compressed air supplied through said slot; g. Supplying a new painting product up to the one or more spray guns, so that the spraying tool is ready to resume painting; h. Removing the spraying tool from the cleaning drawer; and i. Closing the one of the one or more cleaning stations with a return of the drawer into an inside of the one of the one or more the cleaning stations.

7. The method according to claim 6, wherein the method is performed with automatic steps, parts of the spraying booth being provided with actuators under control of a programmable logic controller (PLC), with which the spray booth is provided.

8. The method according to claim 6, wherein when said spraying tool is provided with a draining gun, the painting product and the solvent being first drained with said draining gun.

9. The method according to claim 6, wherein when said brush is at least partially immersed in a small tank containing the solvent, the solvent being supplied through the supply circuit supplying an inside of the one or more spray guns.

10. The method according to claims 6, wherein the pieces to be painted are sprayed intermittently or in a continuous way.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Additional advantages and properties of the present invention are disclosed in the following description, in which exemplary embodiments of the present invention are explained in detail on the basis of the drawings:

[0049] FIG. 1 is an axonometric view of a spray booth according to the invention from the side of the suction tower, provided with two cleaning stations;

[0050] FIG. 2 is a side view of the spray booth from the operator's side, provided with two cleaning stations;

[0051] FIGS. 3A, 3B are axonometric views of the cleaning station separated from the spray booth, the first view being of the closed cleaning station and with its external housing and the second view being of the open cleaning station and deprived of its external housing;

[0052] FIGS. 4A, 4B are a top view and side view of the cleaning station;

[0053] FIGS. 5A, 5B are a top view and axonometric view of the spraying tool;

[0054] FIG. 6 is a longitudinal section of the spray booth with the spraying tools in the positions taken during cleaning;

[0055] FIG. 7 is a side view of the drawer of the cleaning station during a cleaning operation.

DETAILED DESCRITION OF EMBODIMENTS OF THE INVENTION

[0056] FIG. 1 shows an axonometric view of a typical spray booth 100, in which mainly flat or three-dimensional pieces to be painted are conveyed through a closed band conveyer 107 (visible in FIG. 6). The bold arrow shows the conveying direction of the pieces to be painted. A suction tower 112 of known type is provided on the side visible in FIG. 1

[0057] A spray booth according to the invention is provided with two cleaning stations 1, 1′, the first one being disposed on the ingress side of the pieces, and the second one on the egress side. The cleaning stations 1 are mobile, i.e., they can be connected to and disconnected from the spray booth for maintenance.

[0058] FIG. 2 shows a side view of a spray booth 100 according to the invention, in which two cleaning stations 1″, 1′″ are shown in their possible working position. FIG. 2 shows the positions of the cleaning stations 1″, 1′″ when said stations are used for cleaning spraying tools: they are placed on the side opposed to the suction tower 112, said opposed side being known as the operator's side. The bold arrow shows the conveying direction of the pieces to be painted.

[0059] FIGS. 1 and 2 also show the possible positions of the cleaning stations 1. As can be easily understood from FIGS. 1 and 2, when the cleaning stations 1 and 1′ are placed on the same side as the suction tower, the footprint of the spray booth is reduced. Vice versa, placing the two cleaning stations 1″, 1′″ on the operator' side provides the human operator with an easier access to a barrel (not shown) collecting the drained solvent/paint pertaining to the cleaning station. Being able to place the cleaning stations on both sides of the spray booth provides the spray booth with great versatility, which facilitates integration into any production line.

[0060] It is known in the art to provide spray booths 100 with at least one mobile, transparent wall 108, which enables access to the inside of the spray booth. Said cleaning stations 1 are placed in a position adjacent to said spray booth, with their mobile portion (see below) placed in correspondence of said mobile wall 108. This allows providing even spray booth that are already installed in productive lines with at least one cleaning station according to the present invention as a retrofit.

[0061] The cleaning station 1 is tied to the spray booth 100 using fasteners such as screw). Moreover, the cleaning station 1, on the perimeter that comes into contact with the spray booth 100, is provided with suitable seals, e.g., made from polythene, which allow the sealing between said two components and prevents the dispersion of the overspray into the environment outside of the spray booth.

[0062] In a first, more common, embodiment, the spray booth is provided with two arms a spraying tool 10 being provided on each arm. Therefore, normally just two cleaning stations are provided on one of the two sides, two cleaning stations on the suction tower side, or alternatively two cleaning stations on the operator's side. In a second embodiment, said spray booth can be provided with four arms, a spraying tool being provided on each arm. Therefore, four cleaning stations are needed, two on the suction tower side and two on the operator's side.

[0063] FIGS. 3A, 3B show said cleaning station 1 in two axonometric views, said cleaning station 1 being shown disassembled from the spray booth 100. In particular, FIG. 3A shows said cleaning station 1 with its external housing, with a closed cleaning drawer 5, in its rest position. FIG. 3B shows the same cleaning station 1 deprived of its external housing, with the drawer 5 in its opened position, defined as the cleaning position. When said drawer 5 is in its cleaning position, the portion of the drawer 5 protruding from the cleaning station is placed inside the spray booth 100.

[0064] Said drawer 5 is provided with a mobile protective wall 4, hinged and blocked with a magnet and a sensor, so that the spray booth 100 is stopped when the wall 4 is hit by the spraying tool. This is a safety mechanism: when the spraying tool 110 moves from its cleaning position toward the inside of the spray booth, generating a risk of collision, the painting is stopped.

[0065] FIGS. 4A, 4B show said cleaning station 1 with the opened drawer 5, during one of the cleaning steps which will be explained below. In particular FIG. 4A shows the cleaning station in a top view, while FIG. 4B shows the same situation in a side view.

[0066] Said cleaning station 1 comprises:

[0067] A draining tube 6 for collecting painting products and solvents, provided with a mouth 7; said draining tube drains painting products/solvents in a (not shown) barrel generally placed outside the cleaning station. Said barrel is manually emptied by a human operator;

[0068] At least a slot 8 supplying compressed air;

[0069] A cleaning brush 9.

[0070] Said devices are meant for cleaning the spraying tools 110 with which the spray booth 100 is provided.

[0071] FIGS. 5A, 5B show said spraying tool 110 per se; in particular FIG. 5A shows a top view while FIG. 5B shows said spraying tool 110 in an axonometric view.

[0072] Said spraying tool 110 is provided with a supporting structure on which there are provided:

[0073] Four spray guns 101, 102, 103, 104 provided for painting the main surfaces of the pieces to be painted;

[0074] A spray gun 105 provided for the edges of the pieces to be painted;

[0075] An optional draining gun 106, whose function is draining more rapidly the tubings channeling the painting product/solvent to the spraying tool 110.

[0076] FIG. 6 shows a longitudinal section of the spray booth 100; the bold arrow shows the conveying direction of pieces to be painted (not shown). The Figure shows an idle roller 113 and a motorized roller 114 which rotate said closed band 107 on which the pieces to be painted are conveyed. Moreover, the Figure shows the arrangement of the two spraying tools 110, 110′ in correspondence of the drawers 5, 5′ of the cleaning stations 1, 1′, respectively. In this case, the cleaning stations 1, 1′ are arranged on the suction tower 112 side. The two shown positions are the positions taken by the two spraying tools 110, 110′ during cleaning operations. During painting, the two spraying tools 110, 110′ can take any position that is more central with respect to those shown in FIG. 6. It is also worth underlying that in the normal working of the spray booth, only the first spraying tool, e.g., 110, is painting, while, the second spraying tool 110′ is cleaning, and vice versa. Therefore, the spraying tool 110′ is placed in the cleaning position shown in FIG. 6, while the spraying tool 110 is free to move over the pieces to be painted, supported by the closed band 107 for painting.

[0077] It is known that the spraying tools 110, 110′ are provided with four degrees of freedom in their movement:

[0078] A longitudinal direction corresponding to the conveying direction of the pieces to be painted, thanks to the movement of arms 60, 60′ on which spraying tools 110, 110′ are supported;

[0079] A transversal direction, corresponding to the width of the spray booth 100, wherein the spraying tools 110, 110′ move sliding on their respective arm 60, 60′;

[0080] A vertical direction, wherein the spraying tools 110, 110′ come closer/move away to the pieces to be painted;

[0081] Finally, the spraying tools 110, 110′ pivot around their longitudinal axis.

[0082] FIG. 7 shows the inside of the spray booth in a side view. In the cleaning position, the drawer 5 of the cleaning station is extracted from the cleaning station 1 as shown in FIG. 4B, while protruding inside the spray booth 100. The Figure shows the draining tube 6 in a position adjacent to the spray gun 104; in particular the mouth of the tube 7 is placed so that it can collects the fluids (drained paint or solvent) which are drained from each spray gun 101-106 to be channeled into a (not shown) barrel.

[0083] In normal working, when one of the spraying tools must be cleaned e.g., 110, the drawer 5 is moved through its actuator and brought in its cleaning position wherein it protrudes in the spray booth, as shown in FIG. 7. The movement of the drawer can occur only if the arm 60 of the spraying tool is placed outside the opening area of the drawer 5, and moreover is in an area where interference with the arm 60′ of the second spraying tool 110′ is impossible. Now, firstly the arm 60 of the spraying tool to be cleaned moves in the conveying direction to approach the drawer 5; and secondly, the spraying tool 110 moves along its arm 60 to enter into the open drawer 5.

[0084] The method according to the present invention is applied to a spray booth 100 comprising preferably two cleaning stations 1, 1′ placed indifferently on the suction tower side (FIG. 1) or on the operator's side (FIG. 2). It is also possible providing just one cleaning station 1 which is manually moved toward the ingress or the egress of the pieces to be painted, according to need. As already mentioned, the cleaning of one 110 of the two spraying tools is performed by the cleaning station 1 while the spraying tool 110′ is spraying the pieces to be painted, moving freely inside the spray booth 100.

[0085] Said method comprises the following steps:

[0086] a. Inserting the drawer 5 of the cleaning station 1 inside the spray booth 100 (cleaning position);

[0087] b. Inserting the spraying tool 110 provided with spray guns 101, 102, 103, 104, 105 and optionally with a draining gun 106 inside said drawer 5 of the cleaning station 1;

[0088] c. Draining the spray gun supply circuit which channels a first painting product; Obviously said spraying tools 110 are supplied by a (not shown) circuit supplying said painting product to the spraying tool 110, which circuit withdraws said painting product from a reservoir. In order to supply said spraying tools 100 with solvent, the painting product reservoir must be replaced with a solvent reservoir; such replacement can be made manually or automatically, see below;

[0089] d. Optionally, supplying a solvent to spraying guns 101, 102, 103, 104 provided for plane painting and to spraying gun 105 provided for painting edges. The guns 101, 102, 103, 104, 105 are placed one by one in front to the mouth 7 of the draining tube 6. In order to place the edge spray gun in front of the draining tube the tube 6 is to be moved through a pneumatic actuator;

[0090] e. External brushing of spray guns 101, 102, 103, 104, 105, through said brush 9;

[0091] f. External blowing of the spraying tool 110 through compressed air supplied through at least a slot 8. This step has the aim to dry the spraying tool 110 to prevent that drops of solvent or painting product remained on the outside of the spraying tool fall on the pieces to be painted;

[0092] g. Supplying a new painting product to spray guns (of a different color/composition with respect to the previous one) to spray guns 101, 102, 103, 104, 105. Spray guns are positioned in front of the mouth 7 of the draining tube 6 in order to supply the new painting product up to the nozzle while they are open to allow the passage from the solvent/old painting product to the new painting product; the spraying tool 110 is ready to resume painting;

[0093] h. Having the spraying tool 110 leave from the drawer 5 of the cleaning station 1;

[0094] i. Closing the cleaning station 1., and having the drawer 5 return into the inside of the cleaning station in the rest position shown in FIG. 3A.

[0095] The draining spray gun 106 is optional. When provided in the spraying tool 110, the draining steps of the old painting product, of the solvent and of the new painting product are faster. As spray gun 106 is not provided with a spraying nozzle, the diameter of the outlet hole is larger than that of the spraying guns, so as to allow a bigger flow rate than that of spray guns.

[0096] Supplying the subsequent product pushes the previous product out from the supplying circuit, for example, supplying the solvent pushes the old painting product out of the circuit, and the new painting product pushes the solvent out of the circuit. The changes are made upstream, manually replacing the supplying reservoir from which the pump draws, or automatically by using a known system for changing colors.

[0097] When two subsequent painting products are of similar colors and are chemically compatible, e.g., two paints have similar composition, the first one being pale brown and the second one being dark brown, the step d) with the solvent can be omitted.

[0098] The operation of the brush 9 for cleaning the outside of the spray guns may be different:

[0099] In a first case, the brush 9 is at least partially immersed in a small tank containing solvent, from which it is wetted. In this case, the supply of solvent, which is provided to the small tank through the same supplying circuit supplying the inside of spray guns, preferably occurs at a reduced pressure with respect to the normal supply pressure of the circuit of the painting product (e.g., 3 atmospheres in lieu of 100 atmospheres);

[0100] In a second case, the brush 9 dry-brushes the spray guns.

[0101] It should be noted that the cleaning of the outside of the spray guns is performed just for spray guns 101, 102, 103, 104, 105 and not for the draining gun 106.

[0102] The entire above-described method is automatic: the opening/closing of the drawer 5, the approaching of the mouth 7 of the draining tube 6 to one of the spray guns 101-106, the rotation of the spraying tool 110 to bring each spray gun in correspondence of the mouth 7, the replacement of the painting product or solvent to supply the supplying circuit of the spraying tool 110, the actuation of the brush 9, the supply of compressed air through at least one s1o6 8, are all performed by specific actuators, placed under the control of a PLC which is part of the spray booth 100.

[0103] In a completely automatic spray booth, there is provided a plurality of reservoirs containing different painting products and a plurality of pumps. When it is necessary to automatically pass to a different painting product (or to a solvent), changing color systems are used, i.e., systems provided with valves which can supply the supplying circuit of the spray booth by selecting from said plurality of reservoirs placed upstream the control valves. Such changing color systems are well known in the art.

[0104] As mentioned, the cleaning of one 110′ of the two spraying tools is performed by the cleaning station 1′ while the other spraying tool 110 is spraying the pieces to be painted, freely moving inside the spray booth 100. At the end of the method steps, the spraying tool 110 can start the cleaning steps according to the above-specified method, while the spraying tool 110′ can start painting the subsequent payload of pieces to be painted. Basically, the cleaning operation on the first of the spraying tools 110, 110′ occurs at the same time as the painting operation by the second spraying tool 110′, 110. Consequently, no downtime is needed to clean the spraying tools, which occurs in masked time.

[0105] This way, the hourly productivity of the spray booth 100 is maximized, enabling work on production batches as small as needed. Potentially, every single payload can be painted with a different color.

LIST OF REFERENCE NUMBERS

[0106] 1 cleaning station [0107] 4 mobile panel [0108] 5 drawer [0109] 6 draining tube [0110] 7 tube mouth [0111] 8 slot [0112] 9 brush [0113] 60 spraying tool arm [0114] 100 spray booth [0115] 101 spray gun [0116] 102 spray gun [0117] 103 spray gun [0118] 104 spray gun [0119] 105 spray gun [0120] 106 draining gun [0121] 107 closed band conveyor [0122] 108 transparent mobile wall [0123] 110 spraying tool [0124] 112 suction tower [0125] 113 idle roller [0126] 114 motorized roller