Electrostatic spray coating system

An electrostatic spray coating system comprising:

• a high voltages electrostatic supply for providing electrostatic voltages in excess of 50 KV,
• a spray device for emitting coating particles toward an article to be coated,
• an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device,
• an electrical path interconnecting the high voltage supply and the electrode composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and disposed along said electrical path to provide electrical current flow paths primarily substantially longitudinally between said electrode and high voltage supply each said fiber having a length in the approximate range of 1 m-50 m, said fibers collectively having a total diameter measured generally transversely to said path in the approximate range of 10.sup.-2 cm.-1 cm. and a specific resistivity selected to provide a total resistance between said electrode and high voltage supply in the approximate range of 1M-1000M ohms.

An electrostatic spray coating system comprising:

• a spray device for emitting coating particles toward an article to be coated,
• an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device,
• a high voltage electrostatic supply located remote from said spray device for providing electrostatic voltages in excess of 50 KV,
• a first high voltage path terminating at opposite ends interconnected between the remote high voltage supply and the spray device, said first path composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and extending between said opposite ends of said path to provide electrical current flow paths primarily substantially longitudinally along said first path, each said fiber having a length measured between said opposite first path ends in the approximate range of 1 m-50 m, said fibers collectively having a total diameter measured generally transversely to said first path in the approximate range of 10.sup.-2 cm.-1 cm. and a specific resistivity selected to provide a total resistance measured between the opposite ends of said first path in the approximate range of 1M-(1000-N)M ohms, where N is a number less than 1000, and
• a second high voltage path in the spray device interconnected between said first path and the electrode, said second path composed a plurality of continuous silicon carbide fibers electrically connected primarily in parallel, disposed between said first path and said electrode to provide electrical current flow paths primarily substantially longitudinally therebetween, and collectively having a total diameter measured generally transversely to said second path in the approximate range of 10.sup.-2 cm.-1 cm. and a length and specific resistivity selected to provide a total resistance between said first path and said electrode in the approximate range of NM ohms.

An electrostatic spray coating system comprising:

• a spray device for emitting coating particles toward an article to be coated,
• an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device,
• a high voltage electrostatic supply mounted to said spray device for providing electrostatic voltages in excess of 50 KV at a location spaced from the electrode, and
• an electrical path terminating at opposite ends interconnecting the high voltage supply and the electrode composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and disposed between said opposite ends to provide electrical current flow paths substantially longitudinally along said paths, said fibers having a length measured along said path, a total diameter measured generally transversely to said path, and specific resistivity selected to provide a total resistance between the opposite ends thereof in the approximate range of 1M-1000 ohms.

An electrostatic spray assembly comprising:

• a spray device for emitting coating particles toward an article to be coated,
• an electrode mounted to the spray device in charging relationship to coating emitted by the spray device,
• a high voltage electrostatic supply mounted to said spray device for providing electrostatic voltages in excess of 50 KV at a location spaced from the electrode, and
• an electrical path terminating at opposite ends thereof interconnecting the high voltage supply and the electrode composed of a plurality of substantially equal length continuous silicon carbide fibers electrically connected primarily in parallel, disposed between said opposite ends to provide electrical current flow paths primarily substantially longitudinally along said path, and collectively having a length measured along said path, a diameter measured generally transversely to said path, and a specific resistivity selected to provide a total resistance between the opposite ends thereof in the approximate range of 1M-1000M ohms.

A method of electrostatic spray coating an article comprising the steps of:

• interconnecting between an electrode and a high voltage supply a cable having opposite ends and composed of substantially equal length continuous silicon carbide fibers electrically connected primarily in parallel and disposed along said cable to provide electrical current flow paths primarily substantially longitudinally along the length of said cable, said fibers each having a length measured along the length of said cable in the approximate range of 1 m-50 m, said plurality of parallel-connected fibers collectively having a diameter measured generally transversely to the length of said cable in the approximte range of 10.sup.-2 cm.-1 cm. and a specific resistivity selected fo provide a total resistance between said opposite ends of said cable in the approximate range of 1M-1000M ohms, and
• energizing the fibers with an electrostatic voltage in excess of 50 KV while insulated to avoid dielectric breakdown to cause electrical current to flow along the length of the cable between the electrode and the high voltage supply,
• transporting coating material in electrostatic charge transfer relationship to the energized electrode to electrostatically charge the coating material, and
• directing charged particles of coating material toward an article to the coated while maintaining the article at 1000an electrostatic potential different from that of the electrode.

A method of electrostatic spray coating an article with a spray device having a coating-charging electrode, comprising the steps of:

• generating in the spray device a high electrostatic voltage at a location spaced from the electrode,
• applying high voltage to the electrode over a high voltage path between the electrode and the location in the spray device whereat the high electrostatic voltage is generated, the high voltage path including a plurality of substantially equal length continuous silicon carbide fibers electrically connected primarily in parallel and disposed along said high voltage path to provide electrical current flow paths primarily substantially longitudinally therealong, said plurality of parallel-connected fibers having a length measured along said high voltage path, total diameter measured generally transversely to said high voltage path, and a specific resistivity selected to provide a total resistance between the electrode and the said location in the approximate range of 1M-1000M ohms,
• transporting coating material in electrostatic charging transfer relationship to the energized electrode to electrostatically charge the coating material, and
• directing charge particles of coating material toward an article to be coated while maintaining the article at an electrostatic potential different from that of the electrode.

A method of electrostatic spray coating an article with a spray device having a coating-charging electrode, comprising the steps of:

• generating a high electrostatic voltage at a remote location spaced from the spray device,
• applying high voltage to the electrode over a high voltage path between the electrode and the remote location whereat the high voltage is generated,
• interposing in series-circuit relation in the high voltage path resistive means composed of a plurality of primarily parallel-connected continuous silicon carbide fibers disposed to provide electrical current flow paths primarily substantially longitudinally along said high voltage path, each said fiber having a length measured along said high voltage path in the approximate range of 1 m-50 m, said fibers collectively having a diameter measured perpendicular to aid high voltage path in the approximate range of 10.sup.-2 cm.-1 cm., and said fibers having a specific resisitivity selected to provide a total resistance of said resistive means in the approximate range of 1M-1000M ohms,
• transporting coating material in electrostatic charge transfer relationship to the energized electrode to electrostatically charge the coating material, and
• directing charged particles of coating material toward an article to be coated while maintaining the article at an electrostatic potential different from that of the electrode.

A method of electrostatic spray coating an article with a spray device having a coating-charging electrode, comprising the steps of:

• generating a high electrostatic voltage at a location remote from the spray device,
• transmitting high voltage from the remote location to the spray device over a first path terminting at opposite ends and composed of a plurality of primarily parallel-connected continuous silicon carbide fibers disposed between said ends to provide electrical current flow paths primarily substantially longitudinally along said first path, each said fiber having a length measured along said first path in the approximate range of 1 m-50 m, a total diameter measured generally transversely to said first path in the approximate range of 10.sup.-2 cm.-1 cm., and a specific resistivity selected to provide a total resistance between opposite ends of said first path in the approximate range of 1M-(1000-N)M ohms, where N is a number less than 1000,
• transmitting high voltage in the spray device from the first path to the electrode over a second path composed of a plurality of primarily parallel-connected continuous silicon carbide fibers disposed between said first path and said electrode to provide electrical current flow paths primarily substantially longitudinally along said second path, said second path fibers collectively having a total diameter measured generally transversely to said second path in the approximate range of 10.sup.-2 cm.-1 cm., and a length measured along said second path and specific resistivity selected to provide a total resistance between said first path and said electrode in the approximate range of NM ohms, and
• directing charged particles of coating material toward an article to be coated while maintaining the article at an electrostatic potential different from that of the electrode.

An electrical cable assembly for transmitting electrostatic voltage from an electrostatic power supply to an electrostatic spray coating device, comprising in combination:

• an elongated continuous flexible resistor consisting substantially of silicon carbide fibers disposed to provide electrical current flow paths primariy substantially longitudinally therealong;
• an electrically insulating flexible jacket surrounding and enveloping said silicon carbide resistor;
• and
• connection means at each end of said flexible resistor for facilitating connection of said flexible resistor between an electrostatic power supply and an electrostatic spray coating device.

For use in an electrostatic spray coating system having a high voltage electrostatic supply, the combination comprising:

• a resistorized spray coating device for emitting charged coating particles toward an article to be coated;
• an electrode mounted to said device in charging relationship to coating particles emitted by said spray device;
• a resistive element consisting substantially of silicon carbide fibers disposed to provide electrical current flow paths primarily substantially longitudinally therealong;
• and
• electrical connection means electrically connected to said resistive silicon carbide fiber element to facilitate connecting said resistive silicon carbide fiber element in an electrical circuit between said high voltage power supply and said electrode.

An electrostatic spray coating system comprising:

• a high voltage electrostatic supply for providing electrostatic voltages in excess of 50 KV;
• a spray device for emitting coating particles toward an article to be coated;
• an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device;
• and
• a resistive electrical path interconnecting the high voltage supply and the electrode consisting substantially of silicon carbide fibers disposed to provide electrical current flow paths primarily substantially longitudinally therealong.

An electrostatic spray coating system comprising:

• a spray device for emitting coating particles toward an article to be coated;
• an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device;
• a high voltage electrostatic supply located remote from said spray device for providing electrostatic voltages in excess of 50 KV;
• a first high voltage resistive electrical path interconnected between the remote high voltage supply and the spray device, said first path consisting substantially of flexible silicon carbide filaments electrically connected primarily in parallel and disposed to provide electrical current flow paths primarily substantially longitudinally along the length of said first path;
• and
• a second high voltage resistive electrical path interconnected between the first path and the electrode, said second path consisting substantially of at least one silicon carbide filament.

An electrostatic spray coating system comprising:

• a spray device for emitting coating particles toward an article to be coated;
• an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device;
• a high voltage electrostatic supply mounted to said spray device for providing electrostatic voltages in excess of 50 KV at a location spaced from the electrode;
• and
• a resistive electrical path interconnecting the high voltage supply and the electrode consisting substantially of silicon carbide filaments disposed to provide electrical current flow paths primarily substantially longitudinally therealong.