Claims
- 1. An apparatus for electrostatically coating workpieces with an electrically conductive coating material, said apparatus comprising: a spraying device having an atomizer (1), an internal housing (6) supporting said atomizer (1), said atomizer (1) including a spraying head (2) extending from said internal housing (6); a supply line (3) conducting the coating material from a storage-system to said spraying head (2), said supply line (3) and said spraying head (2) being at ground potential; charging electrodes (10) distributed about said spraying head (2) and connected to a high-voltage supply for charging the coating material and producing an electric field; an electrode-holding arrangement (11, 12, 15) made of an insulating material disposed about said internal housing (6); said apparatus characterized by including potential-control means having a surface interconnecting said internal housing (6) and said charging electrodes (10) for approximating the radial-potential pattern continuously over said surface of said potential control means to the radial-potential distribution of the coating material sprayed.
- 2. An apparatus as set forth in claim 1 further characterized by said internal housing (6) being disposed within an external housing (4) fabricated from an insulating material.
- 3. An apparatus as set forth in claim 2 further characterized by said electrode-holding arrangement (11, 12, 15) including at least one support (15) extending from said external housing (4).
- 4. An apparatus as set forth in claim 2, further characterized by at least one of said electrode-holding arrangement (11, 12, 15) and said external housing (4) comprising said potential-control means.
- 5. An apparatus as set forth in either of claims 1 or 3, wherein said electrode-holding arrangement (11, 12, 15) presents a side thereof facing in the direction of said electric field further characterized by said side of said electrode-holding arrangement (11, 12, 15) being made of an insulating material, the surface-potential of said insulating material approximating the potential-distribution in the radial direction of the material sprayed.
- 6. An apparatus as set forth in claim 3, further characterized by said support (15) being at least partially fabricated of ceramic.
- 7. An apparatus as set forth in claim 1, further characterized by said electrode-holding arrangement (11, 12, 15) including an annular element (12) disposed concentrically about said spraying head (2), said annular element (12) fabricated from a polyacetal plastic.
- 8. An apparatus as set forth in claim 1, further characterized by said electrode-holding arrangement (11, 12, 15) being at least partially fabricated from material having a surface-resistance similar to that of a polyacetal material.
- 9. An apparatus as set forth in claim 1 wherein said spraying head (2) includes a cover (5) disposed thereabout, further characterized by at least one of said spraying head (2) and said cover (5) being at least partially fabricated of a material suitable for potential-control.
- 10. An apparatus as set forth in claim 1 further characterized by said charging electrodes (10) being generally needle-shaped and having exposed front ends distributed radially about said spraying head (2).
- 11. An apparatus as set forth in claim 1 further characterized by said electrode-holding arrangement (11, 12, 15) being at least partially fabricated from material having a surface-resistance similar to that of a ceramic material.
- 12. A method for electrostatically coating workpieces with an electrically conductive coating material, comprising the steps of: electrically grounding an atomizer (1); discharging the coating material from the atomizer (1) with a predominantly radial component of movement; supporting charging electrodes (10) from the atomizer (1) at a radially outward spacing; electrically charging the coating material sprayed from the atomizer (1) by corona discharge to form a radial potential electrical charge distribution in the coating material having the highest electrical potential proximate the electrodes (10) and the lowest electrical potential proximate the grounded atomizer (1); and characterized by including the step of approximating the radial potential pattern over a continuous surface interconnecting the atomizer (1) and the electrodes (10) to the radial potential electrical charge distribution in the coating material sprayed.
- 13. A method as set forth in claim 12 further characterized by covering at least a portion of the electrodes (10) and atomizer (1) with an insulating material having a surface potential approximating the potential distribution in the radial direction of the material sprayed.
- 14. A method as set forth in claim 13 further characterized by rotating a spraying head (2) of the atomizer (1) to discharge the coating material in the radial direction.
- 15. A method as set forth in claim 14 further characterized by moving a stream of air through an air-gap (20) disposed about an external housing (4') of the atomizer (1).
Priority Claims (2)
Number |
Date |
Country |
Kind |
3709508 |
Mar 1987 |
DEX |
|
8709948[U] |
Jul 1987 |
DEX |
|
Parent Case Info
This application is a continuation, division, of application Ser. No. 166,193, filed Mar. 10, 1988 now abandoned.
US Referenced Citations (13)
Foreign Referenced Citations (3)
Number |
Date |
Country |
3609240 |
Sep 1987 |
DEX |
126675 |
Mar 1977 |
DDX |
901969 |
Jul 1962 |
GBX |
Continuations (1)
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Number |
Date |
Country |
Parent |
166193 |
Mar 1988 |
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