Electrostatic spraying device for spraying articles with powdered material

A spraying device for spraying powdered material on an article, the device comprising:

• a body having an upstream region and a downstream end;
• an axially extending powder channel formed in the body and having a spraying opening at the downstream end of the body, the powder channel being shaped for guiding the powdered material downstream to the spraying opening;
• a support extending through at least a portion of the powder channel, the portion of the powder channel having an annular transverse cross-section defined around the support;
• a gas channel defined and extending in the support for conducting gas therethrough;
• at least one gas outlet orifice extending between the gas channel and the powder channel for providing gas flow from the gas channel into the powder channel;
• an electric line extending in the gas channel and an electrode connected to the electric line and extending into the orifice, the electrode including an electrode tip defined at the free end of the electrode, and the free end being located near the powder channel;
• means for flowing gas past the electrode and into the powder channel for transferring charge from the electrode into the powder channel;
• and
• the axial distance from the electrode tip to the spraying opening being in the range of 12 to 16 mm.

A spraying device for spraying powdered material on an article, the device comprising:

• a body having an upstream region and a downstream end;
• an axially extending powder channel formed in the body and having a spraying opening at the downstream end of the body, the powder channel being shaped for guiding the powdered material downstream to the spraying opening;
• a support extending through at least a portion of the powder channel, the portion of the powder channel having an annular transverse cross-section defined around the support;
• a gas channel defined and extending in the support for conducting gas therethrough;
• at least one gas outlet orifice extending between the gas channel and the powder channel for providing gas flow from the gas channel into the powder channel;
• an electric line extending in the gas channel and an electrode connected to the electric line and extending into the orifice, the electrode including an electrode tip defined at the free end of the electrode, and the free end being located near the powder channel;
• means for flowing gas past the electrode and into the powder channel for transferring charge from the electrode into the powder channel;
• and
• the powder channel having an outer diameter of predetermined value at a location thereof directly upstream of the spraying opening and wherein the axial distance from an opening of the orifice into the powder channel to the spraying opening is equal to about one half of the predetermined diameter.

A spraying device for spraying powdered material on an article, the device comprising:

• a body having an upstream region and a downstream end;
• an axially extending powder channel formed in the body and having a spraying opening at the downstream end of the body, the powder channel being shaped for guiding the powdered material downstream to the spraying opening;
• a support extending through at least a portion of the powder channel, the portion of the powder channel having an annular transverse cross-section defined around the support;
• a gas channel defined and extending in the support for conducting gas therethrough;
• at least one gas outlet orifice extending between the gas channel and the powder channel for providing gas flow from the gas channel into the powder channel;
• an electric line extending in the gas channel and an electrode connected to the electric line and extending into the orifice, the electrode including an electrode tip defined at the free end of the electrode, and the free end being located near the powder channel;
• means for flowing gas past the electrode and into the powder channel for transferring charge from the electrode into the powder channel;
• powder deflection means coupled to the gas channel and disposed in front and downstream of the spraying opening, the deflection means being effective for creating a gas wall which extends generally transversely to the axial direction of the spraying device for dispersing the powdered material issuing from the spraying opening;
• and
• the gas deflection means comprising:
• an extension of the support located in the powder channel, the support extension protruding from the body of the spraying device past the spraying opening, a respective gas channel extending axially through the support extension, and a support extension opening in the support extension adjacent the end of the support extension, the support extension opening communicating with the gas channel in the support extension and being shaped to guide gas out of the support extension generally radially to form the gas wall.