APPARATUS FOR COATING WITH ELECTROSTATICALLY CHARGED PARTICULATE MATERIALS

• US 3,740,612 A
• Filed: 05/28/1971
• Issued: 06/19/1973
• Est. Priority Date: 05/28/1971
• Status: Expired due to Term

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Daniel M. Rogers, William D. Gauthier
• Inventors: Rogers, Daniel M., Gauthier, William D.
• Primary Examiner(s): Kaplan, Morris
• Assistant Examiner(s): Millstein, Leo
• Application Number:
  US05/147,752
• Time in Patent Office: 753 Days
• Field of Search: 118/621,627,629,7 117/17,93.4 239/15,3 317/3
• US Class Current: 361/227
• CPC Class Codes: B05B 5/032 for spraying particulate materials
• CPC Class Codes: B05B 5/1683 specially adapted for particulate materials
• CPC Class Codes: B05B 7/1472 Powder extracted from a powder container in a direction substantially opposite to gravity by a suction device dipped into the powder

Abstract

An improved control device for apparatus for coating articles with an electrostatically charged material in discrete form. The apparatus includes a nozzle having an inlet and a discharge outlet for the particulate material, an electrode for electrostatically charging the particulate material and at least one passage for directing a stream of vortex gas to impart a vortical motion to the particulate material discharged from the nozzle. A trigger on the apparatus operates first and second gas valves. The first valve controls a stream of gas to the vortex gas passages in the nozzle for controlling the pattern of the sprayed material and the second valve operates a pneumatic control to cause a high voltage to be applied to the electrode in the nozzle and to cause a pump to deliver to the nozzle inlet a stream of gas having the particulate material dispersed therein. In a preferred form, the trigger opens the first valve before the second valve and closes the second valve before the first valve. Provision is made for easily cleaning residual material from the pump, the nozzle and an interconnecting tube when changing the material to be sprayed.

Claims

1. In apparatus for dispersing electrostatically charged material in discrete particulate form, said apparatus including a nozzle having an inlet and a discharge outlet for the particulate material, an electrode for electrostatically charging the particulate material and at least one passage for directing a stream of gas to alter the shape of the pattern of particulate material discharged from said nozzle, an improved control comprising, in combination, a source of compressed gas, first control valve means for delivering and controlling a stream of compressed gas from said source to said at least one passage in said nozzle, a second valve means connected to said gas source, means responsive to actuation of said second valve means for applying a high voltage to said electrode in said nozzle, means responsive to actuation of said second valve means for delivering to said nozzle inlet a stream of gas having the particulate material dispersed therein, and means for jointly controlling said first valve means and actuating said second valve means.

2. In apparatus for dispersing an electrostatically charged material in discrete particulate form, an improved control, as set forth in claim 1, wherein said means for delivering to said nozzle inlet a stream of gas having the particulate material dispersed therein includes a reservoir for holding a supply of the particulate material, a pump responsive to actuation of said second valve means for delivering a stream of gas having the particulate material dispersed therein, means connecting said pump to said nozzle inlet, and means for fluIdizing particulate material held in said reservoir.

3. In apparatus for dispersing an electrostatically charged material in discrete particulate form, an improved control, as set forth in claim 2, and including means for purging particulate material from said nozzle, said connecting means and said pump.

4. In apparatus for dispersing an electrostatically charged material in discrete particulate form, an improved control, as set forth in claim 3, wherein said purging means comprises valve means for selectively delivering compressed gas from said source to said pump for blowing particulate material from said nozzle, said connecting means and said pump.

5. In apparatus for dispersing an electrostatically charged material in discrete particulate form, an improved control, as set forth in claim 4, wherein said pump has a vertical orientation, whereby, when said second valve means is unactuated, material falls from said pump into said container to facilitate purging material from said pump.

6. In apparatus for dispersing an electrostatically charged material in discrete particulate form, an improved control, as set forth in claim 1, wherein said jointly controlling means adjustably controls said first control valve means continuously between closed and opened positions to vary the flow of gas to said at least one passage in said nozzle and thereby to vary the pattern of particulate material dispersed from said nozzle.

7. In apparatus for dispersing an electrostatically charged material in discrete particulate form, an improved control, as set forth in claim 1, wherein said second valve means includes a chamber connected to said gas source, means for venting said chamber to the atmosphere, restriction means for limiting gas flow from said source to said chamber whereby the gas pressure in said chamber is normally below the gas pressure from said source, and wherein said means for actuating said second valve means closes said vent to increase the gas pressure in said chamber, each of said means responsive to actuation of said second valve means being responsive to an increase in gas pressure in said chamber.

8. In apparatus for dispersing an electrostatically charged material in discrete particulate form, an improved control, as set forth in claim 1, wherein said means for controlling said first valve means and actuating said second valve means at least partially opens said first valve means prior to actuating said second valve means.