US3558052A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for spraying electrostatic dry powder
Assignee: F I N D Inc
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Filing: 1968-10-31
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Granted: 1971-01-26
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Expires: 1988-10-31
Abstract
Abstract Dry nonconductive powder passes from a hopper by means of a vibrating plate through an adjustable, nonclogging eductor and is directed by means of a current of air issuing through a rectangular orifice from a variable volume plenum chamber into a venturi. The powder particles pass into the entrance of the venturi in a stream of air having a rectangular flow pattern or cross section and from the venturi through a discharge nozzle and from the discharge nozzle onto a substrate to be coated. Corona wires are located in the proximity of the issuing end of the discharge nozzle so as to charge the powder particles in order to direct them onto a substrate. A positive draft is maintained downstream from the venturi entrance and serves to pick up excess powder particles which are pneumatically conveyed back to the feed hopper.
Inventors
- 👤 John P Dunn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:18
CPC Classifications
B; B05; B05B; B05B7/00; B05B7/14; B05B7/1404; B05B7/1468; B05B5/00; B05B5/025; B05B5/03; B05B5/032; B05B5/16; B05B5/1683; B05B7/1477
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
14 words
Apparatus as in claim 1 further comprising a nozzle attached to the venturi exit.
Claim 2
Dependent Claim
29 words
Apparatus as in claim 2 wherein the nozzle is interchangeable with other nozzles having different cross-sectional outlet openings and the same inlet openings cooperating with the venturi exit end.
Claim 3
Dependent Claim
22 words
Spray apparatus as in claim 1 wherein the venturi is rectangular in cross section and the venturi entrance is rectangular in section.
Claim 4
Dependent Claim
43 words
Apparatus as in claim 1 wherein one wall of the gas inlet chamber has an orifice therein through which gas is directed into the venturi entrance, the wall being adjustable to vary the gas flow pattern of the gas entering the venturi entrance.
Claim 5
Dependent Claim
18 words
A spray apparatus as in claim 5 wherein the adjustable wall is movable relative to the venturi entrance.
Claim 6
Dependent Claim
61 words
A spray apparatus as in claim 1 wherein one wall of the gas inlet chamber has an orifice therein through which gas is directed into the venturi entrance, the gas inlet chamber movably mounted within the spray housing, whereby said wall is adjustably positioned relative to the falling powder so as to vary the pattern of gas entering the venturi entrance.
Claim 7
Dependent Claim
27 words
A spray apparatus as in claim 1 further comprising a return eductor connected to the excess powder exit for returning excess powder to a powder feed means.
Claim 8
Dependent Claim
40 words
A spray apparatus as in claim 8 further comprising: a gas inlet in the excess powder exit prior to the return system whereby said inlet creates a positive draft serving to guide the excess powder into he return eductor system.
Claim 9
Dependent Claim
27 words
A spray apparatus as in claim 1 wherein the powder feed means includes a powder hopper, a vibratory screen, and a conduit connected to the powder inlet.
Claim 10
Dependent Claim
22 words
An apparatus as in claim 1 wherein particle charging conductors are mounted adjacent the powder exit but upstream from the powder exit.
Claim 11
Dependent Claim
20 words
An apparatus as in claim 9 wherein said conducting wires are mounted so as to completely surround the powder exit.
Claim 12
Dependent Claim
16 words
An apparatus as defined in claim 12 wherein said conductors are arranged in a rectangular configuration.
Claim 13
Dependent Claim
21 words
A spray apparatus as defined in claim 13 wherein the conductors are adjustably attached to the outside of the spray housing.
Claim 14
Dependent Claim
49 words
A spray apparatus as defined in claim 14 wherein a conductor is supported by an arm pivotally mounted on the spray housing so as to be cApable of positioning said conductor in one of a number of positions along an arcuate path in the proximity of the powder exit.
Claim 15
Dependent Claim
27 words
An apparatus as in claim 1 wherein there are a number of spray housings connected in series with a single feed hopper and a common eductor system.
Claim 16
Independent Claim
140 words
A method for the electrostatic spraying of dry particles onto a substrate, said method comprising: a. feeding by gravity a uniform ribbon of powder particles past a directed gas flow; b. forming a directed gas flow having a specifically and uniformly shaped cross section; c. directing said gas flow onto the flow of particles traveling transversely to said directed gas flow; d. directing a portion of said powder particles carried by said gas flow and said gas flow into a venturi; e. conveying powder particles not carried by the gas flow into the venturi to recycle the powder particled; f. separating the powder particles in the venturi from each other through the action of the venturi; g. guiding the particles into an electrical charging zone adjacent the venturi outlet, and h. charging said particles and directing them onto a substrate.
Claim 17
Dependent Claim
37 words
A method of spraying particles as described in claim 17 further comprising forming said gas flow so as to have a rectangular cross section whereby said flow of particles in the venturi has a rectangular cross section.
Claim 18
Dependent Claim
19 words
Apparatus as in claim 1, wherein the gas flow for carrying powder is less than 600 feet per second.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-25 | 1974-07-27 | 1975-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-25 | 1978-07-27 | 1979-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-25 | 1982-07-27 | 1983-01-26 | $7700.00 | Window Closed / Lapsed |