TECHNICAL FIELD

The present invention relates to a spray booth of the type employed in wet or powder spraying of objects.

BACKGROUND ART

A number of different designs and constructions of spray booths are previously known in the art for the above-mentioned purpose. As one example of such a prior art design, mention might be made of a spray booth which has an elongate, tunnel-shaped casing with a longitudinal slot-shaped aperture disposed in the roof of the spray booth, through which aperture a carrier passes for those objects which are conveyed in the longitudinal direction of the spray booth and are sprayed therein. The spray booth of this type is produced from sheet material and is often provided, on the inside, with a coating which is intended to reduce adhesion from falling powder. Furthermore, the spray booth is provided with some type of device for the suction extraction of excess powder.

A spray booth of this type may function satisfactorily in the manufacture of long product series, but entails considerable problems in short series runs in which change of powder quality or colour must be carried out frequently. The reason for these problems is that the entire interior of the spray booth must be carefully cleaned before such change can take place. Such a cleaning operation takes considerable time and, consequently, entails expensive operational downtime.

A spray booth of the above-considered type is also so expensive that it is hardly realistic to employ several spray booths, one for each colour or powder quality.

PROBLEM STRUCTURE

The present invention has for its object to realise a spray booth of the type disclosed by way of introduction, the spray booth being designed in such a manner as to be so economical that several spray booths can be employed

contemporaneously, one for each colour, powder quality or type of liquid paint.

The present invention further has for its object to realise a spray booth which, as far as possible, minimises the adhesion of the sprayed material onto the inner defining walls of the spray booth. The present invention yet further has for its object to realise a spray booth which may be collapsed to relatively compact dimensions so that a non-operational spray booth can be removed and re-erected and put into operation when the remaining material quality or colour in the spray booth is to be used once again,

SOLUTION

The objects forming the basis of the present invention will be attained if the spray booth intimated by way of introduction is characterized in that the defining surfaces of the spray booth substantially consist of a flexible foil, fabric or sheet material, preferably a non-reinforced or reinforced plastic foil; and that the defining surfaces are provided with skeletal elements in the form of inflatable channels, bodies or wall portions which, in the inflated state, retain the defining surfaces in their intended positions.

One preferred embodiment of the spray booth according to the present invention is suitably also characterized in that it is in the form of a tunnel with substantially open ends and a longitudinally directed through-aperture disposed in an upper defining surface for the passage of a carrier for such objects as are to be sprayed, a longitudinal channel with a suction extraction aperture being provided in connection with a lower defining surface, and the channel being carried by a carrier on which the defining surfaces of the spray booth may, in the deflated state, be collapsible.

Further advantages will be attained if the spray booth according to the present invention is also given one or more of the characterizing features as set forth in appended Claims 3-5.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detail hereinbelow, with particular reference to the accompanying Drawings. In the accompanying Drawings:

Fig. 1 is a perspective view of one embodiment of a spray booth according to the present invention; and

Fig. 2 shows a system of skeletal, inflatable elements which may be employed in a modified spray booth according to Fig. 1.

DESCRIPTION OF PREFERRED EMBODIMENT

Fig. 1 shows schematically and in perspective one embodiment of the present invention of a spray booth intended for powder spraying of such objects as are conveyed in a conveyor depending from the roof.

In Fig. 1 , reference numeral 1 relates to a carrier which may have the form of an upwardly open gutter or box with side surfaces 2 and end surfaces 3 (the end surface most proximal the observer being omitted). The carrier 1 is of approximately the same, or possibly somewhat greater length than the rest of the spray booth and may be provided with support legs, transport wheels or the like (not shown) which facilitate adjustment of the spray booth in the vertical direction and permit simple transport of the booth.

A tube 4 is disposed along the central region of the carrier and in the longitudinal direction of the spray booth, the tube forming a suction extraction channel from the spray booth. The suction extraction channel is provided, in its upper surface, with a substantially continuous, longitudinal and slot-shaped aperture 5 which forms a suction extraction aperture from the interior of the spray booth. For reasons given below, a number of spans may possibly be provided which divide up the slot-shaped aperture into shorter sections.

The major portion of the laterally located defining surfaces 6 of the spray booth, its upper defining surfaces 7 and its lower defining surfaces 8 consist of a flexible and foldable material, such as a foil, an impregnated fabric, or sheet material, preferably a non-reinforced or reinforced plastic foil. In order to retain the defining surfaces of the spray booth in their intended positions, there are disposed, in the spray booth, a number of inflatable channels or bodies which act as skeletal support elements.

The skeletal elements may be designed as tubular sealed channels, possibly flow-wise mutually interconnected, and consisting of end wall channels 9

which extend along the ends of the defining surfaces both along the lower lateral defining and the upper defining surfaces. The channels further include longitudinal channels which may consist of upper channels 10 on either side of the upper aperture 11 of the spray booth. The longitudinal channels further include upper corner channels 12 and lower corner channels 13. The spray booth may possibly be provided with additional vertical channels corresponding to the end wall channels 9 but disposed, one or more, along the length of the spray booth in order thereby to stanchion and provide configurational stability to the large surfaces constituted by, for example, the side surfaces of the spray booth.

Between the above-discussed channels 9, 10, 12 and 13, the defining surfaces of the spray booth consist of a single, possibly two or more layers of the above-mentioned flexible material. An opening may readily be made in this material, quite simply by the use of a knife or a pair of scissors, through which opening a spray gun may be passed into the interior of the spray booth. Hereby, a high degree of flexibility is afforded in terms of choice of position for such an opening.

As has been considered above, the spray booth consists of an inflatable channel system produced from a flexible and sealing material. This channel system supports the defining walls produced from the flexible and foldable foil or sheet material. It follows from this that, on inflation of the channel system, the spray booth will assume the position of use as shown in Fig. 1. If the air or filler gas/liquid is discharged from the channel system, it is, however, possible to fold together the entire spray booth such that the material thereof can be carried on the carrier, or alternatively packed down into the carrier designed as a box which may then be removed in compact dimensions without cleaning in order to be re-erected and re-used when the same powder quality or colour is to be employed.

In order to improve configurational stability in the inflated spray booth when in the operative position, anchorages or brackets may be provided along the end edges of the spray booth for contemplated skeletal elements produced from substantially rigid tube or rod material. Corresponding anchorages and rigidifying rods or tubes may possibly be employed for supplementing the rigϊdifying effect from the longitudinal upper channels 10.

The employment of these extra rigidifying- elements may be of importance in such cases when the extraction of air from the suction extraction channel 4 takes place at large flow rates, since, in such an event, a certain partial vacuum may be formed in the spray booth despite its substantially open ends. Without the employment of the extra rigidifying elements, this partial vacuum might possibly suck in the sides towards one another so that the aperture 11 would not be of the intended size or at its intended position. The above- considered stays transversely of the longitudinal direction of the suction extraction aperture 5 serve the same purpose, namely to insure that this aperture is not pinched together by the pressure difference which may prevail over the aperture.

Fig. 2 shows in perspective a portion of the channel system which is employed according to the present invention in order to impart form to the spray booth. It is clearly apparent from this Figure that, in addition to the channels 9 at the ends of the spray booth, there may be provided additional upstanding channels 14 in the lateral defining surfaces of the spray booth, and corresponding, recumbent channels 15 in the upper defining surface of the spray booth. Possibly, channels which correspond to the recumbent channels 15 may also be provided in the lower defining surface 8 of the spray booth.

It is apparent from Fig. 1 that the lower corner channels 13 appropriately rest on the upper edges of the side surfaces 2 or equivalent support members upstanding from the carrier in order thereby to reduce the flexural load on recumbent channels disposed in the bottom surface of the spray booth.

In the embodiment according to Fig. 2, those foil sheets which form the defining surfaces of the spray booth and which cover the open surfaces between the channels may be glued, welded or otherwise permanently secured in the channels. However, it is also possible according to the present invention to render these foil sheets replaceable by providing them with a rupturable or separable binder, by the use of Velcro™ fasteners, by the use of zip-like fixing devices etc. Hereby, such a sheet piece may readily be replaced once an opening in the sheet piece has fulfilled its function and is no longer needed.

For securing the foil material which forms the defining surfaces of the spray booth in the suction extraction channel 4, the channel may, on either side of its

aperture 5, be provided with undercut spaces which extend along the edges of the aperture and in which the plastic material with thickened portions can be inserted in the longitudinal direction of the channel 4. Hereby, it will be a simple matter to replace a possibly damaged or used (permanently spoilt) part of the spray booth.

DESCRIPTION OF ALTERNATIVE EMBODIMENTS

The above-described technique of building up a spray booth can, naturally, also be applied in such spray booths as are intended for wet spraying. In such an event, the spray booth may be in the form of an upright box with a distal defining wall, lateral defining walls and an upper defining wall. In this instance, the spraying takes place in a direction into the box and will strike at least the further (distal) defining wall. By a suitable choice of material for the booth, cleaning may be facilitated and, furthermore, the booth may - in the same manner as in the embodiment described above - readily be collapsed together when it is not used, in order once again to be brought out when the colour employed in the booth is to be used again. A booth of this type can, naturally, also be employed for powder spraying.

In the foregoing, the spray booth has been described as designed with a system of skeletal channels whose interspaces are covered by, for instance, foil sheets. However, it is also possible according to the present invention to design the spray booth with certain portions of its defining surfaces to be double-walled so that larger surface portions of the defining surfaces of the booth will form configurationally stabilizing bodies or wall portions. In the extreme case, the entire spray booth can be constructed in this manner, in which event the booth will then be provided beforehand with apertures for the passage of spray guns.

The present invention may be further modified without departing from the spirit and scope of the appended Claims.