Coating apparatus – Projection or spray type – With hood or offtake for waste material
Patent
1997-02-27
1999-01-19
Simmons, David A.
Coating apparatus
Projection or spray type
With hood or offtake for waste material
118309, 55DIG46, 454 50, B05B 128
Patent
active
058610626
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/DE96/01055 filed Jun. 14, 1996.
BACKGROUND OF INVENTION
The invention relates to an appliance for the spray coating of workpieces with paint, which has at least two coating booths, arrange on a conveying track for the workpieces, and a spray device. Such a spray-coating appliance is suitable particularly for electrostatic powder coating.
The principle of electrostatic powder coating is employed primarily for the lacquering of sheet-metal and finished parts, since it is particularly economical and environmentally friendly. Furthermore, high throughput quantities of material to be lacquered can be achieved with powder-coating systems.
In conventional powder-coating systems, however, as in lacquering systems working according to other paint-coating methods, problems arise when the colour is changed. In particular, in order to achieve a homogeneous and uniform coating along with a high throughput of material to be lacquered, a concentrated paint-powder jet is directed onto the workpiece to be lacquered, but only some of the paint powder adheres to the workpiece, whereas the remaining paint powder settles in the system.
The known coating systems therefore have a suction-extraction device., in order to return the paint-powder excess into the paint-powder circuit. However, paint-powder particles always remain adhering particularly to the coating-booth walls and, in the event of a change of colour, cause colour mixing and consequently an impurity. In order to avoid this, the coating booth has to be cleaned whenever the colour is changed. This therefore always gives rise to costly standstill times in the coating system.
Moreover, particularly in an electrostatic powder-coating system, a relatively great amount of time is needed for cleaning during a colour change, since the paint-powder particles, by virtue of their electrical charge, often adhere firmly to the coating booths.
In order to allow a rapid colour change in powder-coating systems, powder-coating systems possessing a plurality of coating booths for different colours, so that one booth can always be cleaned alternately for the colour change, are already being used. CH 668 008 A5 describes such a powder-coating system having two coating booths which are arranged parallel to one another and are supplied by means of a switch via a common conveying track. However, this system is very costly, since two complete coating booths, each provided with a spray device, are necessary.
SUMMARY OF THE INVENTION
The object of the invention is, therefore, to provide a cost-effective appliance for the spray coating of workpieces, which allows a rapid colour change.
In the spray coating appliance according to the invention, at least two coating booths are arranged on the conveying track for the workpieces and are designed in two parts, the booth parts being separable from one another, so that the spray device can be transferred between the coating booths.
In the spray-coating appliance according to the invention, the standstill times during the colour change can be reduced substantially, since, by virtue of the two-part design of the coating booths, the spray device can be transferred simply and quickly between the coating booths having the different paints. In this case, the cleaning of the spray device consisting of a spray-gun arrangement can be carried out easily by blowing it clear by means of compressed air. Use of only one spray device for both coating booths further substantially reduces the production costs in comparison with a system having two completely equipped coating booths.
According to a preferred embodiment of the invention, the booth parts can be moved apart from one another transversely relative to the conveying track for the workpieces. The coating booth is thus accessible in a simple way and can be cleaned quickly and effectively.
According to a preferred embodiment of the invention, the coating booths are designed cylindrically. This leads to a further substantial reduction in the cleaning times during the colour
REFERENCES:
patent: 4640220 (1987-02-01), Fallas
patent: 4715314 (1987-12-01), Ramseier et al.
patent: 4932316 (1990-06-01), Josefsson
Padgett Calvin
Simmons David A.
Tegometall (International) AG
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