Apparatus for spraying a plurality of different powders

• US 3,873,024 A
• Filed: 03/12/1973
• Issued: 03/25/1975
• Est. Priority Date: 08/13/1971
• Status: Expired due to Term

• Current Assignee: Kenneth E. Pollard, Richard O. Probst
• Original Assignee: Kenneth E. Pollard, Richard O. Probst
• Inventors: Probst, Richard O., Pollard, Kenneth E.
• Primary Examiner(s): Wood, Jr., M. Henson
• Assistant Examiner(s): Love, John J.
• Application Number:
  US05/340,316
• Time in Patent Office: 743 Days
• Field of Search: 239/15,80.3,112,113,304-307,303,397,400,399 118/311
• US Class Current: 239/704
• CPC Class Codes: B05B 15/55 using cleaning fluids
• CPC Class Codes: B05B 5/032 for spraying particulate materials
• CPC Class Codes: B05B 5/1683 specially adapted for particulate materials
• CPC Class Codes: B05D 1/06 Applying particulate materials

Abstract

This disclosure includes a color change means for and method of coating surfaces of articles with a spray of powder particles of one color or a spray including a plurality of different powder particles, the particles being entrained in a gas, such as air. The powder spray device is, preferably, an electrostatic spray device for depositing the particles of powder on a surface to be coated. A plurality of separate passageways in the spray device, one for conveying each powder, are connected to separate sources of powder. Particles of the desired powder or powders are withdrawn from the source or sources containing them. Powder particles flowing into the spray device are conveyed by the passageways to a chamber or compartment within the color change means. A flow of compressed air is introduced to the area where the powder particles emerge from the passageways. An induced flow of air is admitted into the spray device to the rear of termination of the passageways. In operation the powder being sprayed is not retained in the device in significant quantity, a substantially uniform powder distribution is achieved in the spray pattern and the powder particles are provided with momentum sufficient to carry the particles to the vicinity of the surface to be coated.

Claims

1. Apparatus for spraying one or more different powdered materials entrained in air comprising means forming a compartment, a spray orifice connected with the compartment, a plurality of substantially straight passageways with openings to direct a flow of each of the different powdered materials into the compartment, means directing air flow into the compartment and out of the spray orifice to act on the flow of powdered material from each passageway in the compartment, and means for introducing an additional flow of air into the apparatus rearwardly of the compartment to assist in minimizing deleterious feedback of the powder to the unused passageways and to affect its spraying from the spray orifice.

2. The apparatus as claimed in claim 1, wherein the means for introducing an additional flow of air into the apparatus rearwardly of the compartment includes a separate passageway communicating with the atmosphere.

3. The apparatus as set forth in claim 1 wherein the means forming a compartment includes converging and diverging walls forwardly of the openings of the passageways, a first annular air chamber surrounding the compartment and a plurality of air passageways between the annular air chamber and the compartment forwardly of its converging wall, and a second annular air chamber adjacent the forwardmost part of the apparatus with openings adjacent the outer surface of the spray orifice to clean the outer surface at the spray orifice.

4. Apparatus as set forth in claim 1, wherein said means for introducing an additional flow of air into the apparatus includes separate passageways communicating with atmosphere and adapted to admit a flow of air to be induced into the passageways during operation of the apparatus.

5. Apparatus as set forth in claim 4 wherein the axis of each of the separate passageways is at an acute angle with respect to the axis of the passageway with which it communicates.

6. Apparatus for spraying one or more different powdered materials comprising spray forming means, a compartment in the apparatus adjacent the spray-forming means, a plurality of passageways leading to the compartment, each connected with one of a plurality of sources of different powdered material and having terminal portions adapted to deliver one or more of a plurality of different powdered materials into the compartment without delivery of powdered material into the unused passageways, and means to admit air into the compartment including passageways arranged to cooperate with said spray-forming means and to minimize deleterious feedback of powdered material being sprayed into the unused passageways of the apparatus.

7. A device for spraying one or more different powdered materials comprising a body, a spray nozzle formed at the front of the body, a compartment in the body adjacent the spray nozzle, a plurality of passageways in the body opening into the compartment to direct a flow of powdered material into the compartment, a separate passageway between the exterior of the body and the rear of the compartment and adapted to admit a flow of air to be induced into the separate passageway during operation of the device, a first air chamber in the body adapted to communicate with a source of compressed air and communicating with first means in the body to direct a flow of compressed air into the compartment to interact with other body portions encouraging an induced flow of air through the separate passageways into the rear of the compartment, interacting with the powdered material from the plurality of passageways and the spray nozzle in producing a spray, and purging the compartment and nozzle of powdered material upon termination of its delivery to the compartment, an electrostatic charging electrode carried by the body and cooperatively associated with the spray to produce charged spray particles, and a second air chamber in the body communicating with the source of compressed air and with second means to direct a flow of compressed air at the outer surface of the spray nozzle and the electrostatic charging electrode.

8. The device as claimed in claim 7, wherein the spray nozzle and compartment are formed by converging and diverging interior walls of the body, the walls converging forwardly of the passageways, forming a throat adjacent the first means in the body and diverging forwardly of the throat to form the orifice of the spray nozzle, said first means directing air into the compartment substantially tangentially to the diverging walls to swirl the powder about the axis of the spray nozzle.

9. The device as claimed in claim 8, wherein each of the plurality of passageways include a portion adjacent the compartment to direct powdered material from it at the center of the throat formed by converging and diverging walls.

10. A device for mixing and spraying a plurality of different powdered materials comprising a spray-forming means, a compartment in the device adjacent the spray-forming means, a plurality of passageways opening into the compartment, each connected with one of a plurality of sources of different powdered materials to be mixed and sprayed, means to admit air into the compartment at its rear to minimize feedback of powdered material into unused passageways of the apparatus, and means adapted to be connected to a source of compressed air and to deliver into the compartment a flow of air to mix the powder materials from the plurality of passages, to interact with the spray forming means to form a spray of mixed powdered material and to purge the compartment and the spray nozzle of mixed powdered material upon termination of its delivery to the compartment.

11. The device as claimed in claim 10, including an electrostatic charging electrode cooperatively associated with the spray from the spray-forming means and means adapted to be connected to a source of compressed air to direct a flow of compressed air at the outer surface of the spray-forming means and the electrode.

12. The device as set forth in claim 10, wherein said spray-forming means includes a bell-shaped nozzle, said means to admit air into the compartment at its rear includes separate passageways communicating with atmosphere and adapted to admit a flow of air to be induced into the passageways, and said means adapted to be connected to a source of compressed air includes an air chamber in the apparatus communicating with a source of compressed air and means to direct a flow of compressed air into the compartment to interact with the bell-shaped nozzle, encouraging a flow of air through the separate passageways into the rear of the compartment, producing a soft divergent spray from the nozzle and purging the compartment and nozzle of powdered material upon termination of its delivery to the compartment.

13. Apparatus for mixing and spraying a plurality of different powder materials comprising a spray nozzle, a compartment in the apparatus adjacent the spray-nozzle, a plurality of passageways opening into the compartment, each connected with one of a plurality of sources of different powder materials to be mixed and sprayed, means to operate simultaneously a plurality of sources of different powder material and to deliver the different powder materials to different ones of the plurality of passageways, means to admit air into the compartment at its rear to minimize feedback of powder material into the unused passageways of The apparatus, and means adapted to be connected to a source of compressed air and to deliver into the compartment a flow of air to mix the powder materials from the plurality of passageways, to interact with the spray nozzle to form a spray of mixed powder material and to purge the compartment and the spray nozzle of mixed powder material upon termination of its delivery to the compartment.

14. Apparatus as claimed in claim 13, including an electrostatic charging electrode cooperatively associated with the spray from the spray nozzle and means adapted to be connected to a source of compressed air to direct a flow of compressed air at the outer surface of the spray nozzle and the electrode.