Coating apparatus – Projection or spray type – With hood or offtake for waste material
Reexamination Certificate
2001-10-30
2003-09-09
Crispino, Richard (Department: 1734)
Coating apparatus
Projection or spray type
With hood or offtake for waste material
C118S308000, C427S421100, C454S050000
Reexamination Certificate
active
06616764
ABSTRACT:
This application claims the priority of German Patent Application Serial No. 199 20 466.7, filed May 4, 1999, the subject matter of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates especially but not exclusively to a method for cleaning an interior space of a coating booth, in particular a powder coating booth, as well as to a novel design of a cleaning device for such coating booth.
WO 96/12568 discloses a powder coating booth with an interior space which is bounded by a preferably jacket-like peripheral wall, a floor and a ceiling. This coating booth includes a cleaning device which is capable of cleaning the interior space of the powder coating booth by moving in a vertical direction. During the coating operation, this cleaning device is kept ready for use outside the coating booth and can be introduced in a suitable manner into the interior space of the coating booth to clean the interior space of the powder coating booth, and can then clean the entire powder coating booth by moving in a vertical direction. The cleaning device, when not in use, requires storage space near the powder coating booth which adversely affects the compactness of the design of the powder coating booth.
It would therefore be desirable and advantageous to provide an improved method for cleaning an interior space of a coating booth, in particular a powder coating booth, as well as a coating booth, in particular a powder coating booth, to obviate prior art shortcomings and of a configuration which is compact and yet is reliable in operation to clean the effectively and essentially automatically.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a method is provided for cleaning an interior space of the coating booth, in particular a powder coating booth, with an air-supported cleaning device and optionally a recovery device as well as a suction device extending in a longitudinal direction of the booth. The method provides that, if powders of an identical or similar color are employed, then blast air is blown against the surfaces of the interior space of the booth to be cleaned and thereafter directed towards a recovery device. Such cleaning method is particularly suited for a coating operation with a color change “tint-in-tint”, since in this case, due to the small difference in tint of the color powder, the excess powder needs to be cleaned off from the interior space of the booth only coarsely before being transported to the recovery device for reuse. To discharge the excess powder to the recovery unit, a conventional slotted suction device can be used. The conventional device is typically intended to operate only briefly in the coating booth and preferably extends in the longitudinal direction of the booth.
According to a different embodiment of the method for cleaning the interior space of the coating booth, in particular a powder coating booth, with an air-supported cleaning device, optionally also with a recovery device as well as a suction device extending in the longitudinal direction of the booth, blast air is blown against the surfaces of the interior space of the booth to be cleaned for a primary cleaning, for example during a color change, and again suctioned off, and optionally transferred to the recovery device or to a secondary filter. With such an embodiment of the method, steps are carried out simultaneously or alternatingly, wherein blast air is directed to the surfaces of the interior space of the booth to be cleaned and optionally suctioned off with a corresponding additional suction device, which can be provided in addition to the suction device that extends in the longitudinal direction of the booth. The blast air herein blows the powder particles off the corresponding wall surface of the interior space, and the released powder particles are then withdrawn from the interior space of the booth by suction as closely as possible to the release location. By combining the blowing and suction operation, the cleaning process is extremely effective and complete.
According to a preferred embodiment of the method, blast air with a certain pressure is first blown against the surfaces of the interior space of the booth to be cleaned, and the powder particles released by the blast air are subsequently suctioned off while the supply of blast air to the interior space of the booth is stopped. It will be understood that the order of the operation can also be reversed. Moreover, cleaning by alternatingly blowing and suctioning can also be carried out several times. The corresponding processes can be suitably adapted to a particular application.
According to an alternative embodiment of the method, blast air is blown against the surfaces of the interior space of the booth to be cleaned and simultaneously suctioned off, preferably at a different location from the blast air. According to a modification of the cleaning method of the invention, the blast air can be supplied and suctioned off simultaneously.
In all the aforedescribed cleaning methods of the invention, the blowing and/or suction operation can be performed cyclically, optionally several times. The process for a respective cycle is herein selected from previously obtained empirical values and by taking into account the economical impact of the cleaning method.
According to another embodiment, blast air is introduced intermittently or pulse-wise, in order to enhance the release of powder particles from the corresponding surface to be cleaned.
In particular, the blast air can be supplied under a controllable high pressure. In this way, the blast air only needs to be directed during a relatively short time to the respective surfaces of the interior space of the booth to be cleaned. This reduces the time required for carrying out the cleaning method of the invention, thereby significantly reducing the necessary downtime of the booth for cleaning.
Preferably, the cleaning method of the invention also provides that the supply of blast air is discontinued during the coating operation and that the air is withdrawn from the interior space of the booth through the floor and/or a side outlet extending in the longitudinal direction of the booth.
According to another aspect of the invention, a coating booth, in particular a powder coating booth, is provided which has a peripheral wall, a floor and a ceiling that cooperatively bound an interior space. The interior space can be cleaned with a cleaning device moving in a vertical direction. The floor and/or the ceiling of the coating booth are in the form of segments that are separate from the peripheral wall and also include the cleaning device.
The floor and/or the ceiling therefore also support the cleaning device. Alternatively, the cleaning device can be integrated in the floor section and/or the ceiling section. The coating booth of the invention does not require additional storage space for a cleaning device, since the floor section and/or the ceiling section themselves perform the cleaning by moving in a vertical direction. Accordingly, such coating booth can have very compact design and be advantageously employed when installation height and space are limited. Moreover, the appropriate facilities for the cleaning device as well as the appropriate drive units for moving the cleaning device to perform cleaning tasks can also be installed at suitable locations in the powder coating booth. Depending on the height of the booth or other limitations, it may be sufficient to employ for cleaning only the floor section or the ceiling section of the cleaning device; however, but it would also be possible to simultaneously or alternatingly use both the ceiling section and the floor section for cleaning. If both the floor section and the ceiling section are provided with a cleaning device, then one of the cleaning devices could be used for blowing and/or suction, while the other cleaning device could be designed as a fine cleaning device, to be used, for example, for wiping with a sponge or the like. Of course, optionally one of the cleani
Krämer Erich
Krämer Matthias
Calfee Halter & Griswold LLP
Crispino Richard
Lazor Michelle Acevedo
Nordson Corporation
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