EP1312419B1 - 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 a method for cleaning the bottom surface of a Paint booth forming gratings according to the preamble of the claim 1 and an apparatus for carrying out this method.

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. Such a paint booth, according to the preamble of claim 1, is known from DE 9 110 651 U. It is not possible, the paint or other coating agent completely on the to apply to the surface to be coated, even if by electrostatic Effects an attraction of the paint particles through the to be coated Object is generated. A significant component of the coating composition, which is often referred to as "overspray" in the vehicle painting process, does not hit the surface to be coated, but falls due to the Gravity to the ground. The movement of the paint particles is in the paint booth usually due to a particular air flow caused by an individual designed flow control system is generated, controlled. It is in particular make sure that no dirt particles on the freshly painted Hit the surface. A control system for air flow in spray booths is for example from the German patent application DE 199 44 744 A1 known. The air in the paint booth moves from a filter inside Ceiling area on the object to be painted and the spray nozzles for Application of the spray over to the bottom of the spray booth, which is formed by gratings. Under the gratings is located a collecting surface, over which during operation of the paint booth continuously a rinsing liquid flows, to which the air from the spray booth impinges with the paint particles contained therein. Put the paint particles depend on the rinse and become with the rinse liquid to a Liquid filter passed.

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 rinse under the name "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, a gap, called Venturi gap, formed by which the air can escape from the spray booth.

The bars of the gratings of the paint booth are usually by 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, forms through the paint overspray on the bars of the gratings the paint booth a thick paint layer, which flows through the undisturbed the air from the spray booth can hinder. The gratings must be removed from the spray booth and a separate cleaning process be supplied, wherein the adhering to the gratings Paint particles are dissolved and rinsed off. To remove the gratings from the paint booth must be the paint booth of objects to be painted be cleared. The painting process involved in a complex vehicle production process is bound to last for a significant amount of time to be interrupted.

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

Other methods of cleaning the bottom surface of a paint booth forming gratings according to the preamble of claim 1 are made the publications DE 91 10 651.6 U, GB 2 228 186 A, DE 29 00 439 A, US 4 219 155 and FR 2 515 075. In these methods, the Gratings in situ in the paint booth by spraying with a cleaning liquid cleaned under high pressure. In DE 29 00 439 A and the GB 2 228 186 A is a sliding over the gratings with sprayer on a circular orbit rotating spray nozzles described. In the drawings of the Typefaces only the cleaning of empty spray booths is shown from which before cleaning the objects to be painted removed were. Also in the description of these documents is nothing else disclosed. This coincides with the observation of the inventor, namely that before the cleaning of the paint booths from the pollution of the Surfaces of the objects to be painted this completely from the Lackierkabine be cleared out. This means a considerable Time.

The object of the invention is a method for cleaning the gratings a paint booth and a device suitable for its implementation to establish the duration of the interruptions of the operation of the Reduce the paint booth and the costs for cleaning the gratings.

This object is achieved by the totality of the features of Patent claim 1 solved.

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

According to the invention, a method for cleaning the gratings of a Paint booth proposed in the installed state. In short intervals The gratings are placed in their installed position in the field Spray booth cleaned by spraying with a cleaning fluid. This cleaning is preferably done every working day during a usual work break, which lasts 15 to 30 minutes. The spraying takes place preferably by means of a grid described below, over the gratings sliding sprayer, which has a cover, the one Bouncing of the cleaning liquid into the spray booth is prevented. As in this cleaning by means of the sprayer, the objects to be painted remain in the paint booth, it is absolutely necessary, any To avoid rebounding of the cleaning fluid. For this reason During the first cleaning step, the ventilation system described above remains in operation, which is a downward flow of air in the Paint booth generated. Also, the described cleaning cycle of Paint booth with a circulating flushing liquid or a circulating Washing water, in which the paint overspray is recorded, remains in Business. The top down air flow avoids rising of the spray mist resulting liquid mist. The fluid circuit transports the loosened when cleaning the grid Paint particles for the filter system of the paint booth.

In a second step - if necessary - the usual external Grate cleaning performed. For this, the gratings are at the end a longer operating period, preferably every weekend, from the Paint booth removed 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 planned in each working shift and in which the paint shop 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 only is cleaned in 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 can be kept very low, must the complete cleaning in a separate cleaning plant, as far as they are is required at all times, exclusively at times when the entire production plant is shut down.

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 after removing the gratings from the Paint booth to lay a second set of gratings in the paint booth, so that during the next 5 or 6 day operating cycle the dirty gratings can be thoroughly cleaned. Will the Operating time of the production plant for a longer period, for example 2 calendar days, interrupted, can the available break time sufficient to paint the objects to be painted from the spray booth remove the grids to remove (which is usually more than 1 hour Takes time) to clean the gratings and back in the cabin be interpreted before resuming production. In this In this case, the costs can be additionally increased by the new cleaning procedure Lowering that only one set of gratings required for each spray booth is and providing a second rate for switching between Operation and cleaning can be omitted.

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, whereby a renewed adhesion of paint particles and thus a re-pollution of the grid is reduced. Furthermore, by the use of circulating flushing fluid for on-site cleaning Ensure that the carefully set mixing ratio of the rinse liquid from water, coagulants and optionally dispersion or Suspending agent is not changed and thereby adversely affected. at The use of pure water would during the cleaning the Rinsing liquid diluted so that their mixing ratio after each cleaning would have to be adjusted to the optimal functioning of the Ensure flushing liquid. By the water intake that would become Increase total volume of the rinsing liquid, with the risk that a critical value for the total volume is exceeded.

Thus, the inventive use 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 share of the wastewater of the separate cleaning system for gratings, which should be treated separately and to dispose of. The treated wastewater in the spray booth is only increased by a small percentage. This will in no case the Cleaning and filter systems of the paint booth overloaded. The wastewater of the On-site cleaning can be done at essentially no extra cost and without additional effort through the cleaning and filtering of the Paint booth to be 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 is observed.

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 the paint booth rollable, with the spray nozzles on a circular path with rotate a diameter of, for example, 50 cm. The spray nozzles are slanted to the vertical direction. This shows the liquid jet a running in the circumferential direction of the circular path component. Of the Drive of the spray nozzles is thus carried out by the inertia of the ejected Liquid particles. The spray nozzles are on rotatable arms or attached to a rotatable disc and rotate at high speed, so that when moving the sprayer with walking speed over 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 the rinsing liquid mixed with coagulants and optionally further additives the cleaning circuit of the spray booth is used. The known compositions of the rinsing liquid described in the introduction In addition to the coagulation usually have a entklebende effect, so that thereby both the new pollution of the cleaned grate and the removal of paint contaminants is encouraged.

An apparatus for carrying out the method according to the invention includes the above described, over the gratings sliding sprayer with on a circular path 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 about a vertical Axis rotatably attached to the sprayer, wherein the spray nozzle emerging beam a tangent to the circular path extending component having. The oblique arrangement of the spray nozzles has two functions. To the one ensures the running in the direction of the circular path component of Spray jet that the rotatably held spray nozzles with high Turn the speed on the circular path around the axis of rotation. On the other hand the oblique spray ensures that the cleaning liquid of the high speed rotating spray nozzles over the entire surface the bars of the gratings roams. The fast rotation in combination with the slow displacement movement of the sprayer has the consequence that the jets of spray nozzles in closely spaced tracks across the surfaces the bars of the gratings strip, so that a complete cleaning takes place. To ensure that the cleaning is up to the lower edge of the Bars of gratings is done, is the inclination of the spray nozzles to the vertical Direction to choose less than the inclination of one against two each other opposite bars of a grid adjacent lines. As above mentioned, the bars of the gratings consist of very flat and several Centimeters high steel sheets. The distance between two adjacent ones Bars is also several centimeters. It is necessary to ensure that a directed onto the lower edge of a rod spray not from the Top edge of an adjacent bar is covered. For this reason, must the inclination of the spray to be chosen lower than the slope of a Straight lines to the lower edge of a first rod and to the upper edge of a adjacent rod abuts.

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 liquid particles in the area above the spray nozzles. The disc is the alternative solution of a rotatable Armes, which carries a spray nozzle, preferable. An arm generates like that Blade of a lawn mower strong air turbulence below the cover. A rotating disc, however, produces only a small amount Boundary layer flow, the effect at a greater distance to the disk barely effect shows. In addition, a closed pane reduces the risk of that the rotating carrier of the spray nozzle against an obstacle on the Grate bounces and either the obstacle or the carrier of the spray nozzle is damaged.

For the supply of cleaning liquid to the spray nozzle is on the top the disc, which faces the cover, a pressure line arranged, which the spray nozzle with a rotatable coupling piece in the Center of the disc connects. The fixed part of the coupling piece is on the Cover hood attached. The rotatable part of the coupling piece is on the Disk attached and keeps this freely rotating on the cover. The Coupling itself has a fluid channel, which is 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 evenly spaced be distributed on the edge of the disc and each with the same Pressure lines for connection to the centrally arranged on the disc, be equipped rotating part of the coupling piece.

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, from the the circulating rinsing liquid of the cleaning circuit of the paint booth exit. Preferably, this pressure connection with a reservoir for connected this flushing liquid. Furthermore, the device preferably comprises a flexible pressure line, that is a hose, between the pressure port in the paint booth and the pressure fitting on the sprayer.

Fig. 1

eine schematische Darstellung einer miteinem System zur Durchführung des erfindungsgemäßen Verfahrens versehenen Lackierkabine,

Fig. 2

eine Draufsicht auf ein 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

a schematic representation of a paint booth provided with a system for carrying out the method according to the invention,

Fig. 2

a top view of a sprayer,

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, for example a primer, a lake or a clearcoat 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 are not applied to the surface of the car body 2, with and transports them through the bottom of the paint booth 1 through, the is formed by a plurality of gratings 9. The excess paint, too Called "overspray" decreases according to the in Fig. 1 recognizable arrows continue down. The overspray hits the rinsing liquid 10 under the Designation "Venturi scrubber" known device, which the paint overspray largely separated from the air and a filter system supplies. This device consists of two collecting surfaces 11,12. It is ensured, that on the entire surface of the collecting surfaces 11,12 a uninterrupted layer of the rinsing liquid 10 is located, which from lateral Overflow containers on the collecting surfaces 11,12 flows. In addition to those in the Slanted collecting surfaces 11, 12 shown in Fig. 1 are also e.g. from the DE 197 32 208 C2 known step-like collecting surfaces, which are small Form baffles for the continuously supplied rinsing liquid. By the air flow transported down paint particles 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 dispersion in the To keep rinse 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 of the paint booth 1 air flowing through to an air outlet 14. The rinsing liquid 10 is fed through a drain pipe 15 a filter unit 16. Of the Filter system 16 flows the rinsing liquid into a reservoir 17. Off the supply container 17 are the inflow lines 18,19 of Spülflüssigkeitskreislaufs fed to the washing liquid back to the collecting surfaces 11.12 lead.

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

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 the sprayer 23rd The chassis has two located approximately at waist height handles 27 and carries a circular cover 28. The cover 28 has in her Center on a hydraulic coupling piece 29, which a rigid, with the Cover 28 connected upper part 30 and a rotatable member 31st having. To the rigid part 30, a pressure hose 32 is connected. Of 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, the fluid flow of the in the pressure fitting 33rd guided fluid to the coupling piece 29 are interrupted. The Pressure fitting 33 is - as seen in Fig. 1 - with the high pressure port 21 connected for the spray liquid in the spray 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, extending through the rigid part 30th extends through into the rotatable part 31. In the rotatable part 31 branches from the central liquid channel 37 in the form of an inverted T two transverse channels 38 from. At the end of the transverse channels 38 are Connecting pieces 39 are arranged, each having a transverse channel 38 with connect a pressure line 40 on the top of the disc. 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 are horizontal Direction inclined so that the liquid jet coming out of the spray nozzle 36 exit, having a tangent to the circular path extending component. The direction of movement and exit velocity of the liquid from the spray nozzle 36 is indicated in Fig. 6 by the vector V. In the the plane of the circular path on which the spray nozzle 36 moves, lying Tangential component is shown in Fig. 5 and marked with V '.

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 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 bars 41 are complied with. It ensures that regardless of the Incident direction 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 shown in the drawings is used to carry out the used in accordance with the method according to the invention in all breaks at least a portion of the gratings 9 in a painting booth 1 by means of Sprayer 23 is cleaned by a cleaning worker. For big ones Paint booths 1 can also simultaneously several sprayers 23 through several workers in a paint booth 1 are used. During the 15th to 30 minutes, which lasts such a break in general, can at least a part of the gratings 9 cleaned by the sprayer 23 become. In the cleaning process, the adhering to the grid 9 Paint particles dissolved and into the rinsing liquid 10 of the Venturi scrubber directed. As for cleaning with the sprayer 23, the rinsing liquid 10 from the storage container 17 is used by the cleaning process the composition of the rinsing liquid 10 is not affected. The at the Cleaning incurred, mixed with paint particles rinse 10 is passed through the filter system 16, which for filtering such particles is designed. By this cleaning process thus no significant additional costs for the disposal of wastewater from the grate cleaning generated.

By covering the spray nozzles 36 with the cover 28 and through the preferably used, relatively low pressure between 400 and 500 bar is ensured that in this cleaning process no mist of the Cleaning liquid rebounds up into the spray booth 1 and on the there bodies 2 can meet. Effective cleaning too 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 of Paint booth 1 ensured. The rinsing liquid 10 contains coagulants and accelerates the detachment of the paint from the grid 9. Further are usually dispersing and suspending agents in the rinsing liquid which ensure that the detached paint particles in suitable Form taken by the rinsing liquid 10 and the filter system 16 be transported away.

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 removed from the spray booth 1 become.

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 interruptions in production times. In addition, the costs incurred in the complete cleaning, separately to be treated and disposed of wastewater to a minimum. Furthermore, the heavy physical work, which with the removal of the Gratings 9 from the spray booth 1, the transport of the gratings 9 to Cleaning system on special transport racks and replacement 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

211

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 1

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 (13)

1. A method for cleaning the gratings (9) forming the floor surface of a paint booth (1) in situ in the paint booth (1) by spraying with a cleaning liquid (10) at high pressure, characterised by cleaning of the gratings (9) at short time intervals, preferably at least once each working day during a break in work with the articles to be coated remaining in the paint booth, wherein the ventilation installation remains in operation during cleaning and produces a downwardly directed stream of air in the paint booth.
2. A method according to claim 1, characterised in that the gratings (9) are removed from the paint booth (1) after a relatively long period of operation, preferably comprising two or more working days, and are cleaned in a separate cleaning installation.
3. A method according to any one of the preceding claims, characterised in that the cleaning liquid used is a circulating rinsing liquid (10) which flows during painting operation over at least one collecting surface (11, 12) beneath the gratings (9) and is passed through a filter installation (16).
4. A method according to claim 3, characterised in that the rinsing liquid (10) contains a coagulating agent.
5. A method according to claim 3 or claim 4, characterised in that the cleaning circuit, which conveys the rinsing liquid (10) over the collecting surfaces beneath the gratings (9) and through a filter installation, remains in operation while the gratings (9) are being sprayed.
6. A method according to any one of the preceding claims, characterised in that the cleaning liquid (10) is applied by spraying with a spraying apparatus (23) which may be pushed over the gratings (9) and comprises spray nozzles (36) which rotate on a circular trajectory.
7. A method according to claim 6, characterised in that the cleaning liquid (10) is sprayed with a pressure of less than 600 bar.
8. A method according to any one of the preceding claims, characterised in that, once the gratings (9) have been removed from the paint booth (1) for cleaning in the cleaning installation, a second set of gratings (9) are laid out in the paint booth (1).
9. A method according to any one of the preceding claims, characterised in that it is performed using a spraying apparatus (23) which may be pushed over the gratings (9) and comprises spray nozzles (36) which rotate on a circular trajectory.
10. A method according to claim 9, characterised in that the spray nozzles (36) are mounted on the spraying apparatus (23) so as to be rotatable on a circular trajectory around a perpendicular axis, wherein the jet emerging from the spray nozzle (36) comprises a component (V') which runs tangentially to the circular trajectory.
11. A method according to claim 10, characterised in that that the inclination of the spray nozzles (36) to the vertical direction is selected to be less than the inclination of a straight line (G) lying against two opposing bars (41) of a grating (9).
12. A method according to claim 10 or claim 11, characterised in that the spray nozzles (36) are arranged under a cover (28) of the spraying apparatus (23), the cover (28) preferably consisting of steel.
13. A method according to any one of claims 10 to 12, characterised in that the spray nozzles (36) are arranged on the periphery of a disk (35) mounted rotatably under the cover (28), said disk preferably likewise consisting of steel.

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