Coating apparatus – Projection or spray type – With hood or offtake for waste material
Utility Patent
1997-12-16
2001-01-02
Edwards, Laura (Department: 1734)
Coating apparatus
Projection or spray type
With hood or offtake for waste material
C118S069000, C118SDIG007
Utility Patent
active
06168664
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an arrangement for coating objects with water soluble or water dilutable coating materials, in particular in spraying processes with at least one coating region.
Arrangements of the above mentioned general type are known in the art. Such arrangement is utilized for example for spray varnishing, spray enameling, for PTFE coating or for coating with adhesives and the like. During coating of objects in spraying processes there is a main disadvantage that the losses of the coating material are very high. They are caused by a portion of the coating material fog sprayed past the object and can amount to between 30 and 60% of the treating coating material. As a result, the process involves considerable cost and also environmental damage.
For preventing a precipitation of varnish losses identified as an “overspray” on parts of the arrangement, varnishing devices have been proposed in which water-irrigated walls are arranged in the vicinity of the objects to be varnished. Particles of the coating material which heat the walls are taken by the water and collected in collecting troughs. Subsequently, the varnish slurry and the water are separated from one another. The varnish slurry must be then disposed. Other processes in which a partial recovery of the coating material is provided are better. One possibility to provide such a recovery is to use an overspray collecting system. For this purpose, devices for collecting the overspray are arranged around the coating region. The coating material falling on the devices is moisturized and collected in a flowable form. The German patent document DE-OS 41 43 025 also proposes a varnishing method in which the parts of installation in the varnish region are cooled below the dew point of the varnish fog. Thereby, the varnish fog which is sprayed past the objects to be varnished is condensed on the parts of the device and runs down on them. Then it can be caught in a trough and used again after cleaning. Since the dew point of the varnish fog changes in dependence on the surrounding temperature, there is a danger that a drying of the varnish overspray occurs on the parts of the device. Due to the insulating action of the varnish on the separator surface, the surface temperature can increase above the dew point, so that the overspray can dry.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an arrangement for coating objects, which avoids the disadvantages of the prior art.
More particularly, it is an object of present invention to provide an arrangement for coating objects which makes possible an approximately complete recovery of the coating material in a simple manner.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated in an arrangement for coating objects with water soluble or water dilutable coating materials, in which arrangement parts located in a coating region are at least partially cooled and at least one air moistening unit is provided in the coating region.
By the cooling of the parts of the arrangement, a condensation of the air moisture is provided, so that the parts of the arrangement are coated with a thin liquid film. During a change of the dew point on the arrangement, for example because of properties of the coating material or the environment, the required moisture is obtained by additional moisturizing units. This reliably prevents the drying of varnish or other coating materials such as enamel or also multi-component materials. The coating materials run down on the parts of the arrangement or wiped by a further device. They can be used again after testing. For multi-component materials, a reaction of the mixed components is delayed, so that also here a pure-grade recovery of the individual components is possible.
In accordance with another feature of the present invention, the parts of the arrangement can be cooled preferably to a constant temperature below the air temperature in the coating region. It is thereby guaranteed that also with different values of the surrounding temperature and air moisture, a condensation of the air moisture is provided on the parts of the arrangement.
In accordance with still another feature of present invention, a control device controls at least an air moisture unit in dependence on the air temperature so that it provides always a moisture in the coating region til the relative air moisture in the coating region prevents drying of the overspray. At high surrounding temperatures, the water component of the coating material remains constant automatically. An evaporation of the water component of the coating material is not possible, since the surrounding air is saturated with moisture.
The temperature of the parts of the arrangement can be also adjustable in dependence on the treating coating materials. In this way, for example, during treatment of multi-component materials, the treatment time can be adjusted. A premature reaction of the components can be reliably prevented.
In accordance with still another feature of the present invention, preferably the parts of the arrangement are also provided with a surface having anti-adhesion properties with respect to the coating material.
REFERENCES:
patent: 4367787 (1983-01-01), Bradshaw
patent: 4417541 (1983-11-01), Schafer
patent: 4687686 (1987-08-01), Stofleth et al.
patent: 4732784 (1988-03-01), Laroche et al.
patent: 41 14 867 A1 (1992-11-01), None
patent: 41 43 025 A1 (1993-07-01), None
patent: 42 25 503 A1 (1994-02-01), None
patent: 195 24 327 A1 (1996-04-01), None
patent: 0 678 335 A2 (1995-10-01), None
patent: 0 741 052 A2 (1996-11-01), None
Edwards Laura
Range und Heine GmbH
Striker Michael J.
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