Particulate material applicator and pump
A nozzle assembly for a material application device includes an expansion chamber for slowing down the velocity of powder fed to the nozzle from a dense phase pump. The nozzle assembly includes a nozzle insert that forms the expansion chamber and provides air assist function. The nozzle includes an integral deflector, and further includes a passageway for a charging electrode so that the electrical path is routed away from the powder path, while permitting the electrode tip to be centered in the powder spray pattern from the nozzle. The nozzle also includes air wash for the electrode. The nozzle outlet orifice has a cross-sectional area that is equal to or greater than the inlet cross-sectional area so that a slow moving dense phase powder cloud is produced by the nozzle.
1. Apparatus comprising:
an automatic powder coating spray applicator and a support for moving said automatic powder coating spray applicator;
said automatic powder coating spray applicator, comprising:
a three piece housing, wherein the first piece is a front section, the second piece is an elongated middle section, and the third piece is a back section, said middle section being longer than said back section, said front section having a spray nozzle closing its forward end and an open rearward end, said elongated middle section having two open ends, and said back section containing a voltage multiplier and having an open front end and a rearward end closed off by a heat sink plate for said multiplier, a first open end of said elongated middle section being secured to said open front end of said back section and a second open end of said elongated middle section being secured to said open rearward end of said front section, said heat sink plate including a powder coating material connection and an electrical connection, a portion of said back section being mounted on said support for moving said automatic powder coating spray applicator;
a powder flow path extending through a housing from the powder inlet to a powder outlet;
a charging electrode disposed near said spray nozzle; and
an electrical cable that extends from an outlet of said multiplier through said elongated middle section to a current limiting resistive device that is electrically coupled to said cable and said electrode.
2. The apparatus of claim 1 comprising an air tube that extends through said front, middle and back sections of said housing to supply air to said spray nozzle.
3. The apparatus of claim 2 wherein said air tube supplies air that passes through a filter element in said spray nozzle.
4. The apparatus of claim 3 wherein said spray nozzle has an outlet orifice and said air tube supplies air that passes through said filter element in said spray nozzle before being sprayed through said outlet orifice of said spray nozzle.
5. The apparatus of claim 1 wherein said three piece housing is releasably secured together with a tie rod.
6. The apparatus of claim 5 wherein said tie rod comprises a powder tube.