Fluid sprinkling – spraying – and diffusing – Electrostatic type – Induction charging
Patent
1996-09-19
1998-06-16
Weldon, Kevin
Fluid sprinkling, spraying, and diffusing
Electrostatic type
Induction charging
239704, 239706, B05B 5043, B05B 5053
Patent
active
057657629
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a spray gun type electrostatic paint coating machine particularly suitable for use in spray-coating a water-base paint or a metallic paint.
BACKGROUND ART
Generally, paints which have been in use for electrostatic coating can be largely classified into solvent type paints (oil-base paints) which are relatively large in electrical resistance and water-base paints (water paints) which are relatively small in electrical resistance. Further, there have been in use the so-called metallic paints which have metallic powder dispersed in a solvent type paint or in a water-base paint. Similarly to water-base paints, metallic paints are known to be relatively small in electrical resistance. As will be gathered therefrom, the paints which are currently in use have different values in electrical resistance depending upon the type, necessitating to employ different methods for paints of different types in applying voltage thereto in electrostatic spray-coating operations.
More specifically, normally a paint supply passage, a paint tank and a color-changer of a coating machine are grounded during coating operations from a viewpoint of preventing dangerous situations, although solvent type paints have a relatively large electrical resistance. Therefore, in the case of a solvent type paint, even if a high voltage is applied to a center electrode on a spray gun body directly from an external high voltage generator, there is little possibility of the spray gun body being grounded to the earth potential through the paint supply passage. For this reason, with a solvent type paint spray gun, it has been the usual practice to charge paint particles by applying a high voltage directly to the spray gun body.
On the other hand, in the case of a water-base paint or a metallic paint of low electrical resistance, if a high voltage is applied directly to a center electrode provided on a spray gun body, it is very likely that the spray gun body is easily short-circuited to the earth potential, failing to charge paint particles to any practical degree.
In this regard, in the case of a water-base paint or a metallic paint, prior art spray gun type electrostatic paint coating machines employ an external electrode system having an external electrode body located radially outward of a spray gun body which is connected to ground, and supplying a high voltage (e.g., of -60 kV to -90 kV) to the external electrode through a high resistance and high voltage cable.
Shown by way of example in FIGS. 8 and 9 is a prior art spray gun type electrostatic paint coating machine employing an external electrode of the sort as mentioned above.
In these figures, indicated at 1 is a spray gun type electrostatic paint coating machine, which includes a mount member 2 to be fixed on a reciprocator (not shown) or the like, a valve mount structure 3 supporting thereon paint valves 16 and 17 along with a drain valve (not shown), a coating machine head 4 securely fixed on the valve mount structure 3, and an external electrode 5 securely fixed at one side of the valve mount structure 3 and disposed parallel with and outward of the circumference of the coating machine head 4.
The construction of the coating machine head 4 is shown in detail in FIG. 9.
In FIG. 9, the reference 6 denotes a spray gun body of an elongated tubular form, which is formed of an electrically insulating synthetic resin material such as polytetrafluoroethylene (PTFE) or polyethylene terephthalate (PET) or the like. The spray gun body 6 is formed with an rearwardly tapered recess at its fore distal end to provide a nozzle receptacle 6A which receives a paint nozzle 7, which will be described below. The rear or base end of the spray gun body 6 is securely fixed to the valve mount structure 3.
The paint nozzle 7, which is also made of an electrically insulating synthetic resin material such as PTFE, PET or the like, is threaded centrally into the fore distal end of the spray gun body 6, and internally provided with a paint supply passage. In this instanc
REFERENCES:
patent: 3393662 (1968-07-01), Blackwell
patent: 3937401 (1976-02-01), Luderer et al.
patent: 4009829 (1977-03-01), Sickles
patent: 4079894 (1978-03-01), Harjar et al.
patent: 4440349 (1984-04-01), Sickles et al.
patent: 4508265 (1985-04-01), Jido
patent: 4611762 (1986-09-01), Turner et al.
patent: 4771949 (1988-09-01), Behr et al.
patent: 4854506 (1989-08-01), Noakes et al.
Lee Hoyang
Takayama Shinichi
ABB Industry K.K.
Weldon Kevin
LandOfFree
Spray gun type electrostatic paint coating machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Spray gun type electrostatic paint coating machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spray gun type electrostatic paint coating machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1716566