Coating apparatus – Projection or spray type – With hood or offtake for waste material
Reexamination Certificate
1998-10-23
2001-02-13
Crispino, Richard (Department: 1734)
Coating apparatus
Projection or spray type
With hood or offtake for waste material
C118S308000, C118S309000, C118S314000, C427S472000, C427S479000, C427S301000, C454S050000
Reexamination Certificate
active
06187098
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a powder coating cabin, and in particular to a powder coating cabin of column-shaped design and of a type including a housing having a cabin ceiling and a cabin bottom, and a coating unit arranged on the housing for spraying powder onto an object.
In the field of powder coating, that need for a frequent change of paint is more and more demanded so that the cleaning of powder coating cabins becomes increasingly important. In this context, reference is made to commonly owned copending international patent application PCT/EP 95/04115, the disclosure of which is incorporated herein by reference, which discloses configurations of powder coating cabins which may have door-shaped gates for defining pre-coating and final coating sites and, possibly, have a closeable bore for passage of powder spray coating devices. Further disclosed in the above-referred international patent application are various embodiments of cleaning units for effecting a simplified purging of the interior space of the housing by use of compressed air and/or suction air and/or wet cleaning elements. The cleaning unit is movable in vertical direction, i.e. in vertical direction of the housing, to clean the inner wall surfaces of the housing when the housing is closed and forms a closed container. The cleaning unit is moved into the operative cleaning phase through the ceiling or laterally by opening the door-shaped gates for formation of the pre-coating and/or final coating sites. After closing the doors and the slots, the cleaning unit can be operated to carry out a cleaning of the inner wall surfaces of the housing. Practice has shown however that sufficient backup space must be provided laterally or above outside the housing for arrangement of the cleaning unit in the stand-by position so that the manner of loading and operating the powder coating cabin is restricted. In addition, there is also a risk of contamination of the cleaning unit in the stand-by position. In particular powder particles may remain on the cleaning unit, resulting in a risk of encountering undesired powder mixtures. Cleansing of the cleaning unit itself is relatively cumbersome and requires mostly manual labor.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide an improved powder coating cabin, obviating the afore-stated drawbacks.
In particular, it is an object of the present invention to provide an improved powder coating cabin which is of compact configuration.
It is still another object of the present invention to provide an improved powder coating cabin which allows a fully automatic cleaning of the interior housing space in a space-saving manner and allows an automatic purification of the automatic cleaning unit itself.
These objects, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing a column-like housing defining an interior space between a ceiling and a bottom, with the bottom being substantially of flat configuration, and a coating unit for spraying powder onto an object. Preferably, the powder coating unit is further provided with a cleaning unit which is so received in the housing as to be movable between a stand-by position in which the cleaning unit is arranged at least partially underneath the bottom and an operative phase for automatically cleaning at least the inner wall surfaces of the housing, whereby the bottom is suitably so designed as to clear a passage for the cleaning unit.
As a result of the flat configuration of the cabin bottom, the housing of the powder coating cabin according to the present invention can be so designed as to exploit an area underneath the bottom for accommodation of the cleaning unit in the stand-by position, while yet being prevented from interfering with the entry of the object being coated and the operation of the powder coating cabin so that the risk of damaging the cleaning unit as well as its susceptibility to contamination are significantly reduced. By opening and closing the bottom of the housing, the cleaning unit housed underneath the bottom in stand-by position can be used to realize a cleaning operation of the interior space of the housing by entering the interior space from below. After closing the bottom, the cleaning operation can be carried out. The coating process thus is not adversely affected even when carrying out the coating operation in a continuous fashion.
According to another feature of the present invention, the cleaning unit is so designed as to be adjustable in a vertical direction of the housing for automatically cleaning at least the inside wall surfaces of the housing. The coating unit includes a spray coating device which projects into the interior space through at least one bore in the housing, a pre-coating site secured to the housing and having a gate mechanism movable between a first position in which access to the interior space is closed and a second position in which access to the interior space is open to allow pre-coating of the object, and a final coating site secured to the housing and having a gate mechanism movable between a first position in which access to the interior space is closed and a second position in which access to the interior space is open to allow final coating of the object.
Preferably, the cleaning unit has at least one scavenger arm adapted to sweep over the bottom during operation of the coating unit, and a cleaning member adapted for cleaning the inside wall surfaces of the interior space. The scavenger arm may be provided with scrapers such as scraping lips and/or blow nozzles. The blow nozzles may be so aligned as to point laterally in direction towards the housing wall, and blow nozzles may be provided which point upwardly for cleaning the cabin ceiling during cleaning operation. The scavenger arm can sweep the bottom also during coating operation and transport powder accumulating on the bottom or in vicinity thereto, even during coating operation, to associated exhaust systems so that this powder can be recovered and returned into the powder cycle without stoppage of the powder coating cabin, resulting in an efficient and powder-saving operation. During cleaning operation, the scavenger arm in conjunction with the respectively arranged blow nozzles can be used for cleaning the ceiling when elevating the cleaning unit inside the housing towards the cabin ceiling. Suitably, when the ceiling is formed with a slotted opening for allowing entry and continuous advance of a suspended object to be coated into the powder coating cabin, the cleaning unit is suitably provided with an outwardly projecting strip-like bar which closes the slotted opening during cleaning operation.
Preferably, the cleaning unit is able to spin about a substantially vertical axis to realize an extremely efficient cleaning of the interior space, including possibly formed slots. Moreover, this spinning motion of the cleaning unit can also advantageously be exploited when carrying out a purification of the cleaning unit in the stand-by position inside a cleansing compartment formed underneath the bottom of the housing.
According to another feature of the present invention, the housing has at least one slit extending longitudinally along a vertical extension of the housing between the ceiling and the bottom, with at least one exhaust duct being connected to the interior space of the housing via the slit. Preferably, the housing has two such slits extending longitudinally along a vertical extension of the housing in diametrically opposite disposition, with two such exhaust ducts arranged in diametrically opposite disposition, adjacent pre-coating and final coating sites, if provided, whereby one of the exhaust ducts is connected to the interior space of the housing via one of the slits, and the other one of the exhaust ducts is connected to the interior space of the housing via the other one of the slits. When providing door-shaped gates on the inlet side and outlet side of the housing which can be opened
Kramer Erich
Kramer Matthias
Crispino Richard
Feiereisen Henry M.
Lorengo J. A.
Nordson Corporation
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