EP1312419A1 - Apparatus and method for cleaning floor gratings in paint booths - Google Patents

Abstract

To clean the lattice grids (9) in a paint spray cabin (1), they are sprayed with a cleaning fluid (10) containing a coagulant under a high pressure of ≤ 600 bar, during a break in painting while the painted workpiece is still in place, and preferably at least once every working day. The cleaning action is through a sliding spray unit (23), moved over the lattice grids, with spray jets rotating on a circular path. The cleaning fluid is caught in a trap (11,12) under the lattice grids, and passed to a filter (16).

Description

The invention relates to an apparatus and a method for cleaning the bottom surface of a paint booth forming gratings.

When applying paints, primers and similar organic Surface coating agents, e.g. on bodies in an automobile manufacturing plant, Be specially equipped for this process paint booths used, in which introduced the objects to be coated and moved out again after coating. That's it not possible, the paint or other coating agent completely to apply to the surface to be coated, even if by electrostatic effects an attraction of the paint particles through the is produced coating article. A significant part of the Coating agent, which is often used in the vehicle painting process as "Overspray" is called, does not hit the surface to be coated, but falls to the ground due to gravity. The movement of Paint particles in the paint booth are usually characterized by a special Air flow through an individually designed flow control system is generated, controlled. It is particularly important to ensure that no Apply dirt particles to the freshly painted surface. A control system for the air flow in paint booths is for example from the German Patent Application DE 199 44 744 A1. The air in the Paint booth moves from a filter in the ceiling area to the varnishing object and the spray nozzles for applying the spray over to the floor of the paint booth, which is made of gratings is formed. Under the gratings is a collecting surface, over during the operation of the paint booth continuously a rinsing liquid flows on which the air from the paint booth with the inside impinges paint particles. The paint particles settle on the Rinsing liquid and become with the rinsing liquid to a liquid filter directed.

The rinsing liquid consists partly of water, the coagulant and optionally dispersing or suspending agents are admixed.

The coagulants promote the coagulation of the paint particles in the Liquid, whereby the filtering out of the paint particles from the rinsing liquid is possible. The coagulants usually also avoid the adhesion of the paint particles present in the liquid to the Liquid leading elements. Optionally in the rinsing liquid existing dispersing or suspending agents cause the paint particles form a dispersion or suspension with the rinsing liquid and no difficult to remove paint sludge settles.

Suitable coagulants and dispersants for the rinsing liquid in Paint booths are for example in DE 42 36 530 A1 and in the DE 199 32 766 A1. Special, as rinsing liquid in the cleaning cycle Mixtures usable in a paint booth will too delivered by some manufacturers ready mixed. For example, distributes the company Henkel KGaA such a rinsing liquid under the Designation "Stay Clean".

Between the two of themselves from the side walls of the paint booth in their Center-extending collection areas that slope slightly to the horizontal direction run inclined, forms a gap, called Venturi gap through which the air can escape from the paint booth.

The bars of the gratings of the paint booth are usually from 1 to 2 mm thick and several centimeters high steel sheets formed. After a longer operating time of the paint booth, for example one or two Working days, formed by the paint overspray on the rods of the Gratings of the paint booth a thick layer of paint, which the undisturbed Passage of air from the spray booth can hinder. The Gratings must be removed from the paint booth and one be fed separate cleaning process, in which the on the gratings adhering paint particles are dissolved and rinsed off. To remove The gratings from the paint booth must paint booth from to be painted Be freed. The painting process, which in one complex vehicle production process is involved, must for a be interrupted for a considerable period of time.

The separate cleaning system, which during one or more Working days on the gratings adhering paint residues removed, is with operated a cleaning liquid which solvents or diluents contains and saturated with paint particles after a certain period of time is. The waste water of this cleaning plant has the diluent and Paint particles on and must be disposed of as hazardous waste. Here arise considerable disposal costs.

The object of the invention is a method for cleaning the gratings a paint booth and a device suitable for this purpose, which the duration of the interruptions of the operation of the paint booth and reduce the cost of cleaning the gratings.

This object is achieved according to the invention by the method Cleaning the gratings at short intervals, preferably at least once a day, in situ in the spray booth by spraying with a cleaning fluid under high pressure during a work break.

Removing the gratings for cleaning in a separate cleaning system can either be completely eliminated or only at the end of a very long Operating period of the paint booth, preferably done at the weekend.

According to the invention, a method for cleaning the gratings proposed a paint booth in the installed state. In short Time intervals are the gratings on site in their installed position in the spray booth by spraying with a cleaning fluid cleaned. This cleaning is preferably done every working day during a normal work break, which lasts 15 to 30 minutes. The Spraying is preferably carried out by means of a later described on the gratings sliding sprayer, which is a cover that bounces the cleaning fluid into the paint booth prevented in. As in this cleaning by means of the sprayer to painting objects remain in the spray booth, it is essential necessary to avoid any bouncing of cleaning fluid. For this reason, the top remains during the first cleaning step described ventilation system in operation, which is a downward flow of air generated in the paint booth. Also the described cleaning cycle the spray booth with a circulating flushing fluid or a circulating wash water, in which the paint overspray was added becomes, remains in operation. The top down airflow avoids rising of the liquid mist resulting from the spray sprinkling. The fluid circuit transports the when cleaning the grate dissolved paint particles to the filter system of the paint booth.

In a second step - if necessary - the usual external grate cleaning performed. For this purpose, the gratings at the end of a longer period of operation, preferably every weekend, removed from the spray booth and for cleaning in a separate Cleaning system brought.

The two-stage cleaning process according to the invention avoids that during working shifts the often in three-shift operation 24 Hours a day running production equipment for motor vehicles Interruption of painting operation takes place. Only in the work breaks, which are scheduled in each working shift and in which the Lakkierbetrieb is stopped without the cleaning and ventilation system of the If the spray booth would be switched off, a grate cleaning takes place by means of a movable sprayer. However, this cleaning does not reduce the Operating time available for the operation of the paint booth, since is only cleaned during the planned interruptions of the operating time.

Industrial manufacturing plants with paint booths are usually at least once a week, usually on one or two days of Weekend, stopped. Because of the on-site cleaning with the Sprayer, the contamination of the gratings are kept very low can, the complete cleaning in a separate cleaning plant, as far as it is necessary at all times, in which the entire production plant is at a standstill.

Depending on the duration of the planned interruption of the operating time of the production plant At the weekend, different procedures for the external Cleaning be used. For example, if the interruption is only 1 Working day, it is recommended to remove after removing the gratings the paint booth a second set of gratings in the paint booth for the next 5 or 6 days of operation Thoroughly clean the soiled grates can. Is the operating time of the manufacturing plant for a longer Period, for example, 2 calendar days, interrupted, can the Available break time sufficient to paint objects to remove from the paint booth, to remove the gratings (what usually takes more than 1 hour to complete), the gratings to clean and re-design in the cabin before the manufacturing plant is resumed. In this case, the costs can be reduced by the In addition, new cleaning methods reduce the fact that for each spray booth only one set of gratings is required and the provision of one second sentence for the change between operation and cleaning accounts can.

Since - as mentioned - preferably the circulation of the rinsing liquid (also Called washing water) of the cleaning circuit of the paint booth during the cleaning with the sprayer is maintained at a preferred embodiment of the method as a cleaning liquid the called circulating flushing liquid itself used. This process feature has several significant advantages. For one, the circumferential is Rinsing fluid with a significant amount of coagulant offset and arranged so that the sticking of the paint particles largely is avoided. When cleaning the gratings with the revolving Rinsing liquid thus becomes the surface of the gratings with the rinsing liquid wetted, causing a re-adhesion of paint particles and thus a renewed contamination of the grid is reduced. Furthermore is by using the circulating flushing fluid for on-site cleaning Ensure that the carefully set mixing ratio the rinsing liquid of water, coagulant and optionally Dispersing or suspending agent not changed and thereby disadvantageous being affected. When using pure water would be during the Cleaning the rinsing liquid diluted so that their mixing ratio after Every cleaning would have to be readjusted to ensure optimum functionality to ensure the rinsing liquid. By the water intake would increase the total volume of the washing liquid, the danger that a critical value for the total volume is exceeded.

Thus, the use according to the invention of the rinsing liquid ensures that neither the total volume of the rinsing fluid is affected nor their material composition is varied. The resulting from the cleaning Wastewater settles like the washing water of the cleaning cycle of the Painting plant from the circulating rinsing liquid and dispersed therein Paint particles together. This mixture can readily be found in the Cleaning circuit of the spray booth existing filter system fed be, with the paint particles are filtered out. By the invention On-site cleaning thus accounts for the largest proportion of wastewater the separate cleaning system for gratings, which should be treated separately and to dispose of. The wastewater to be treated in the paint booth is only increased by a small percentage. This will be never overloaded the cleaning and filtration systems of the paint booth. The sewage of the on-site cleaning can be essentially without additional Costs and without additional effort through the cleaning and filtering devices the paint booth are worked up. The resulting Residues correspond to the residues from the normal operation of the Paint booth. Thus, only a small increase in disposal costs to observe.

Preferably, for spraying the cleaning liquid on the Gratings used a sprayer which rotates on a circular path Having spray nozzles. This sprayer is preferably on wheels Rollable through the paint booth, with the spray nozzles on a circular path rotate with a diameter of for example 50 cm. The spray nozzles are tilted to the vertical direction. This shows the liquid jet a running in the circumferential direction of the circular path component. The drive of the spray nozzles is thus effected by the inertia of the ejected liquid particles. The spray nozzles are rotatable Poor or a rotating disc attached and rotate with high Speed, so that when moving the sprayer with walking speed on the gratings effective cleaning of all Areas of the gratings can be achieved.

The cleaning liquid is preferably at a pressure of less than 600 bar, in particular in the range between 400 and 500 bar, on the Gratings sprayed on. Previous attempts at cleaning the gratings by Spraying with water usually required a spray pressure of 1000 bar. At such a high pressure, it could not be avoided that Spray mist of cleaning water penetrates into the spray booth. This Procedure was therefore not for an in-service spray booth suitable, in which are to be painted objects. The preferred one low pressure of less than 600 bar generated in the inventive Procedures a sufficient cleaning action as a cleaning fluid which mixed with coagulants and optionally other additives Rinsing liquid of the cleaning circuit of the spray booth is used. The known compositions described in the introduction Rinsing liquid in addition to the coagulation usually also a detackifying effect, so that thereby both the new pollution of the cleaned grid and the removal of paint contamination is encouraged.

An apparatus according to the invention for cleaning the gratings comprises the above-described, slidable on the gratings sprayer with a circular orbit rotating spray nozzles.

As mentioned earlier, this sprayer allows for the spray nozzles preferably on a circular path with a diameter of 50 cm with high speed rotation, quick and easy cleaning of the Gratings during a break in operation. The sprayer can with walking speed be pushed over the gratings.

The spray nozzles are preferably on a circular path around one vertical axis rotatably mounted on the sprayer, wherein from the Spray nozzle exiting jet a tangent to the circular path extending Component has. The oblique arrangement of the spray nozzles has two Functions. On the one hand ensures the running in the direction of the circular path Component of the spray for the rotatably held Spray nozzles at high speed on the circular path around the axis of rotation rotate. On the other hand, the oblique spray ensures that the cleaning liquid the high-speed rotating spray nozzles over the entire surface of the bars of the gratings strips. The fast Rotary movement in combination with the slow displacement movement of the Sprayer has the consequence that the jets of the spray nozzles in closely adjacent Webs over the surfaces of the bars of the gratings strip, so that a complete cleaning takes place. To ensure that the Cleaning is done up to the lower edge of the bars of the gratings is the Slope of the spray nozzles to the vertical direction to choose lower than the Inclination of one against two opposing bars of a grid adjacent lines. As mentioned above, the bars consist of Gratings made of very flat and several centimeters high steel sheets. The distance between two adjacent bars is also several Centimeter. It is necessary to ensure that one on the lower edge of a Rod directed spray jet not from the top edge of an adjacent Bar is covered. For this reason, the inclination of the spray jet are chosen to be less than the slope of a straight line to the lower edge a first bar and to the upper edge of an adjacent bar is applied.

As mentioned above, it is necessary that no spray through the Spray nozzles escaping cleaning fluid enters the spray booth. For this reason, the spray nozzles should preferably under a Be arranged cover of the sprayer. In a particularly preferred Embodiment, the spray nozzles on the edge of a rotatable below arranged the cover attached disc. The cover avoids the entry of rebounding fluid particles into the area above the spray nozzles. The disc is the alternative solution of a rotatable arm, which carries a spray nozzle, preferable. An arm Like the blade of a lawnmower, it generates strong air turbulences below the cover. A rotating disc, however, only generates a small boundary layer flow, the greater distance to the disk hardly shows any effect. In addition, by a closed disc the Reduced danger that the rotating carrier of the spray nozzle against a Obstacle on the grate bounces and either the obstacle or the Carrier of the spray nozzle is damaged.

For the supply of cleaning fluid to the spray nozzle is on the Top of the disc, which faces the cover, a pressure line arranged, which the spray nozzle with a rotatable coupling piece in the middle of the disc connects. The fixed part of the coupling piece is attached to the cover. The rotatable part of the coupling is attached to the disc and keeps them freely rotating on the cover. The coupling piece itself has a liquid channel, which of a Pressure fitting on the fixed part and on the top of the cover leads to the rotatable part, which is connected to the disc. The fluid channel is with the pressure line on top of the disc connected. It is important to ensure that the disc has no imbalance. Therefore, two or more spray nozzles should be in uniform Angular intervals be distributed on the edge of the disc and with each same pressure lines for connection to the central on the disc arranged, rotatable part of the coupling piece to be equipped.

As mentioned above, preferably the circulating rinsing liquid of the Cleaning circuit the paint booth used as a cleaning fluid. For this reason, the device for performing the on-site cleaning with the sprayer a pressure connection in the spray booth, off the circulating flushing liquid of the cleaning circuit of the paint booth exit. Preferably, this pressure connection is with a reservoir connected for this flushing liquid. Furthermore, the inventive Device preferably a flexible pressure line, that is one Hose, between the pressure connection in the paint booth and the Pressure fitting on the sprayer.

Fig.

1 eine schematische Darstellung einer mit dem erfindungsgemäßen System versehenen Lackierkabine,

Fig. 2

eine Draufsicht auf ein erfindungsgemäßes Sprühgerät,

Fig. 3

eine Seitenansicht des Sprühgeräts aus Fig. 2,

Fig. 4

eine geschnittene Darstellung der Abdeckhaube mit Drehscheibe und Sprühdüsen des Sprühgeräts aus den Fig. 2 und 3,

Fig. 5

eine Draufsicht auf die Kreisbahn der Bewegung einer Sprühdüse,

Fig. 6

eine Seitenansicht der Bewegungsebene der Sprühdüse,

Fig. 7

eine schematische Darstellung eines Abschnitts eines Gitterrostes mit dem eingezeichneten Vektor des Sprühstrahls.

Details of a preferred embodiment of the invention are described below with reference to the accompanying drawings. The drawings show in:

FIG.

1 is a schematic representation of a painting booth provided with the system according to the invention;

Fig. 2

a top view of a sprayer according to the invention,

Fig. 3

a side view of the sprayer of Fig. 2,

Fig. 4

a sectional view of the cover with turntable and spray nozzles of the spray device of FIGS. 2 and 3,

Fig. 5

a plan view of the circular path of the movement of a spray nozzle,

Fig. 6

a side view of the plane of movement of the spray nozzle,

Fig. 7

a schematic representation of a portion of a grid with the drawn vector of the spray.

FIG. 1 is a schematic representation of a typical paint booth 1 for painting a car body 2 shown. In the paint booth 1 is a transport system 3 shown only schematically for the Car body 2 and a system of sprayers 4,5,6, with the a paint, such as a primer, a lake or a Clear coat is applied to the car body 2.

Inside the paint booth 1 prevails by a in the ceiling located fan 7, 8, downwardly directed airflow. This Air flow tears off the paint particles leaving the spray devices 4,5,6, which is not applied to the surface of the car body 2 with, and transports them through the floor of the paint booth 1 through, which is formed by a plurality of gratings 9. The excess Paint, also called "overspray", decreases correspondingly to that shown in FIG Arrows continue. The overspray hits the rinsing liquid 10 of a under the name "Venturi scrubber" known device, which largely separates the paint overspray from the air and a filter system supplies. This device consists of two collecting surfaces 11,12. It is ensures that spread over the entire surface of the collecting surfaces 11,12 is an uninterrupted layer of the rinsing liquid 10 which from lateral overflow containers on the collecting surfaces 11,12 flows. Next the inclined collecting surfaces 11, 12 shown in FIG. 1 are also e.g. known from DE 197 32 208 C2 step-shaped collecting surfaces, which small barrages for the continuously supplied rinsing liquid form. The paint particles transported downwards by the air flow hit the surface of the rinsing liquid 10. The rinsing liquid 10 contains coagulants and optionally dispersing or suspending agents, which allow the paint particles in a suitable To keep dispersion in the washing liquid 10. The rinsing liquid 10 flows down to a gap 13 between the two collecting surfaces 11,12. This gap 13 is called "venturi gap" and allows the passage the paint booth 1 air flowing through to an air outlet 14. Die Rinsing liquid 10 is through a drain pipe 15 of a filter system 16th fed. From the filter system 16, the rinsing liquid flows into a Reservoir 17. From the reservoir 17 are the inflow 18,19 fed the Spülflüssigkeitskreislaufs, which the flushing liquid again lead to the collecting surfaces 11,12.

From the reservoir 17 is another line 20 from which to a high-pressure connection 21 for rinsing liquid 10 in the painting booth 1 leads. The high pressure port 21 is with a suitable compressor provided or coupled, the rinsing liquid to a pressure of about 500 bar compressed. Via a flexible pressure line 22, that is one pressure-resistant hose, is at the pressure port 21 in the paint booth 1 a sprayer 23 connected, which in Figs. 2 to 4 in more detail is described.

The sprayer 23 is manually pushed by a worker and reminds in its shape to a large industrial vacuum cleaner. It consists of one Chassis with two arranged on a rear axle 24 rigid Wheels 25 and a steerable front wheel 26 at the front end of Sprayer 23. The chassis has two located approximately at waist height Handles 27 and carries a circular cover 28. The cover 28 has a hydraulic coupling 29 in its center, which a rigid, connected to the cover 28 upper part 30th and a rotatable part 31. To the rigid part 30 is a pressure hose 32 connected. The pressure hose 32 leads to a pressure fitting 33 on the sprayer 23. The pressure fitting 33 is provided with a stopcock 34. With the stopcock 34 of the Fluid flow of the guided into the pressure fitting 33 fluid to the Coupling 29 are interrupted. The pressure fitting 33 is - As can be seen in Fig. 1 - with the high pressure port 21 for the spray liquid connected in the paint booth 1.

On the rotatable part 31 of the coupling piece 29 is a disc 35th attached. At the edge of this disc 35 are diametrically opposite each other attached two spray nozzles 36. The coupling piece 29 has a central, axial fluid channel 37 which extends through the rigid Part 30 extends through into the rotatable part 31. In the rotatable Part 31 branches from the central liquid channel 37 in the form of a inverted T two transverse channels 38 from. At the end of the cross channels 38 connecting pieces 39 are arranged, which each have a Transverse channel 38 with a pressure line 40 on the top of the disc connect. Each of the pressure lines 40 leads to one of the spray nozzles 36.

As can be seen in Figs. 5 and 6, the spray nozzles 36 for Horizontal direction inclined so that the liquid jet, which from the Spray nozzle 36 exits, a component running tangentially to the circular path having. The direction of movement and exit velocity of the Liquid from the spray nozzle 36 is indicated by the vector V in FIG. The in the plane of the circular path, on which the spray nozzle 36 Moving, lying tangential component is shown in Fig. 5 and with V ' characterized.

Due to the tangential component V 'emerging from the spray nozzle 36 Liquid becomes the disc 35 visible in Fig. 4, which is the spray nozzles 36 carries, put in a rotary motion. Since the from the spray nozzles 36 exiting liquid under a high pressure up to 500 bar is the rotational speed of the disc 35 is very high.

Fig. 7 shows another criterion, which depends on the direction of the spray nozzle 36 exiting jet of cleaning fluid complied with should be. The in turn represented by the vector V direction of emerging liquid jet should have a lower inclination to the vertical Have direction as a also recognizable in Fig. 7 straight line G, the abuts against two adjacent bars 41 of the grid 9. This law should be at the smallest distance between two adjacent ones Grids 41 are respected. It ensures that regardless of the direction of irradiation of the direction of the vector V in Fig. 7 extending Liquid jet the liquid jet the entire height of a lattice bar 41 rinses to its lower edge before moving to the upper edge of the following grid bar 41 meets.

The device according to the invention shown in the drawings is for Implementation of the method according to the invention used in all Work breaks at least a portion of the gratings 9 in a paint booth 1 cleaned by means of the sprayer 23 by a cleaning worker becomes. In large spray booths 1 can also several at the same time Sprayers 23 used by several workers in a paint booth 1 become. During the 15 to 30 minutes that such a break in work general, at least one can. Part of the gratings 9 through the Sprayer 23 to be cleaned. In the cleaning process are on the grid 9 adhering paint particles dissolved and in the rinsing liquid 10th directed by the venturi scrubber. As for cleaning with the sprayer 23 the Rinsing liquid 10 is used from the reservoir 17 is through the cleaning process, the composition of the rinsing liquid 10 is not affected. The resulting in the cleaning, offset with paint particles Rinsing liquid 10 is passed through the filter system 16, which for Filtration of such particles is designed. Through this cleaning process Thus, no significant additional costs for the disposal of Wastewater generated from the grate cleaning.

By covering the spray nozzles 36 with the cover 28 and through the preferably used, relatively low pressure between 400 and 500 bar ensures that during this cleaning process no spray the cleaning liquid bounces up into the spray booth 1 and can meet on the bodies 2 located there. Effective cleaning even at fairly low pressures is due to the construction of the Sprayer and by the use of the rinsing liquid 10 of the cleaning circuit the paint booth 1 ensured. The rinsing liquid 10 Contains coagulants and accelerates the removal of the paint from the Grid 9. Furthermore, dispersing and suspending agents are generally used contained in the rinsing liquid, which ensure that the detached Paint particles received in a suitable form by the rinsing liquid 10 and be transported to the filter unit 16.

The use of a relatively low pressure still has advantages in concerning the noise pollution of the persons present and cleaning workers. At higher pressures, this noise load increases considerably. In which applied pressure between 400 and 500 bar is the noise pollution on a bearable limit.

It should be noted that the cleaning step according to the invention with the Sprayer in the by health and safety regulations and collective agreements secured breaks and thus the effective operating hours of Lackierkabine 1 influenced in any way. It does not have to be edited Bodywork for this on-site cleaning from the paint booth 1 be removed.

The in the past several times in a week accumulating complete cleaning the gratings 9 can be done much less frequently. It is For example, possible only once a week in the production-free Time on the weekend to perform a complete cleaning of the gratings 9. This significantly reduces the interruption of production times reduced. In addition, the costs incurred in the complete cleaning, separately treated and disposed of wastewater to a minimum reduced. Furthermore, the heavy physical work, which with the Removing the gratings 9 from the painting booth 1, the transport of Gratings 9 for the cleaning system on special transport racks and the replacement of the cleaned gratings 9 is connected considerably reduced.

LIST OF REFERENCE NUMBERS

1

spray booth

2

auto body

3

transport system

4

sprayer

5

sprayer

6

sprayer

7

fan

8th

fan

9

grating

10

rinse

11

collecting area

12

collecting area

13

Venturi gap

14

air outlet

15

waste pipe

16

filter system

17

reservoir

18

inflow

19

inflow

20

management

21

High-pressure connection

22

pressure line

23

spray

24

rear axle

25

rigid wheel

26

front

27

handle

28

cover

29

coupling

30

solid part

31

rotatable part

32

pressure hose

33

Pressure fitting

34

stopcock

35

disc

36

spray nozzle

37

liquid channel

38

Querkanal

39

joint

40

pressure line

41

Gitterstab

V

vector

V '

tangential component

G

Just

Claims (15)

Method for cleaning the gratings (9) forming the bottom surface of a painting booth (1), characterized by cleaning the gratings (9) at short intervals, preferably at least once every working day, in situ in the painting booth (1) by spraying with a cleaning liquid (10) under high pressure during a work break. A method according to claim 1, characterized in that the gratings (9) at the end of a longer, preferably several working days, comprehensive operating period of the paint booth (1) removed and cleaned in a separate cleaning system. A method according to claim 1 or 2, characterized in that a circulating rinsing liquid (10) is used as the cleaning liquid, which flows during the painting over at least one collecting surface (11,12) below the gratings (9) and passed through a filter system (16) becomes. A method according to claim 3, characterized in that the rinsing liquid (10) contains a coagulant. A method according to claim 3 or 4, characterized in that during the spraying of the gratings (9) of the cleaning circuit, which promotes the rinsing liquid (10) on the collecting surfaces below the gratings (9) and through a filter system remains in operation. Method according to one of the preceding claims, characterized in that the cleaning liquid (10) is sprayed with a spray device (23) which can be pushed over the gratings (9) with spray nozzles (36) rotating on a circular path. A method according to claim 6, characterized in that the cleaning liquid (10) is sprayed at a pressure of less than 600 bar. Method according to one of the preceding claims, characterized in that after removal of the gratings (9) from the paint booth (1) for cleaning in the cleaning system, a second set of gratings (9) in the paint booth (1) is designed. Device for cleaning the gratings (9) forming the bottom surface of a painting booth (1), characterized by a spray device (23) which can be pushed over the gratings (9) and has spray nozzles (36) rotating on a circular path. Apparatus according to claim 9, characterized in that the spray nozzles (36) are mounted rotatably on a circular path about a vertical axis on the spray device (23), wherein the jet emerging from the spray nozzle (36) has a component (V ') running tangentially to the circular path. having. Apparatus according to claim 10, characterized in that the inclination of the spray nozzles (36) to the vertical direction is less than the inclination of a against two opposite bars (41) of a grid (9) adjacent straight line (G). Apparatus according to claim 10 or 11, characterized in that the spray nozzles (36) under a cover (28) of the spray device (23) are arranged, wherein the cover (28) is preferably made of steel. Device according to one of claims 10 to 12, characterized in that the spray nozzles (36) are arranged on the edge of a disk (35) fastened rotatably under the covering hood (28), which preferably also consists of steel. Apparatus according to claim 13, characterized in that on the cover (28) facing side of the disc (35) at least one pressure line (40) extends, which a spray nozzle (36) with a rotatable coupling piece (29) in the center of the disc ( 35), wherein the fixed part (30) of the coupling piece (29) on the cover (28) and the rotatable part (31) of the coupling piece (29) on the disc (35) is fixed and the coupling piece (29) has a fluid channel (37-39), which leads from a pressure fitting (33) outside the cover (28) to the pressure line (40). Device according to one of Claims 9 to 14, characterized in that it has a pressure connection (21) arranged in the painting cabin (1), from which a circulating rinsing liquid (10) emerges from the cleaning circuit of the painting booth (1), and that it exits flexible pressure line (22) between the pressure port (21) and a pressure fitting (33) on the spray device (23).

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