Electrostatic powder coating method and apparatus
First Claim
1. An electrostatic powder coating apparatus comprising a spray gun and a powder supply unit, wherein said apparatus is adapted to form a coating film by spraying electrostatically charged powder toward a surface of an electrically grounded product to be coated, and wherein said apparatus further comprises:
- a nozzle tip of said spray gun which includes means for dually functioning to pulverize and disperse a powder that has become aggregated; and
wherein said powder supply unit comprises a fluid-bed type hopper vertically partitioned by a porous member to define therein an upper fluidizing container and a lower air chamber, and includes temperature/humidity control means for adjusting a temperature and humidity of compressed air supplied to said air chamber and means for stirring said powder in said fluidizing container; and
wherein said pulverizing and dispersing means comprises a powder flow passage defined between an inner surface of said nozzle tip and an outer surface of said diffuser which gradually narrows toward a nozzle opening.
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Accused Products
Abstract
An electrostatic powder coating apparatus is provided which includes a spray gun and a powder supply unit. The spray gun includes facilities for dually functioning to both pulverize and disperse the aggregated powder and powder adhesion preventing facilities. Both the pulverizing and dispersing facilities and the powder adhesion prevention facilities are provided in a nozzle lip of the spray gun of the electrostatic powder coating apparatus. The powder supply unit includes a temperature/humidity control facilities for adjusting the temperature and humidity of the compressed air supplied to an air chamber within the powder supply unit.
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Citations
10 Claims
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1. An electrostatic powder coating apparatus comprising a spray gun and a powder supply unit, wherein said apparatus is adapted to form a coating film by spraying electrostatically charged powder toward a surface of an electrically grounded product to be coated, and wherein said apparatus further comprises:
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a nozzle tip of said spray gun which includes means for dually functioning to pulverize and disperse a powder that has become aggregated; and wherein said powder supply unit comprises a fluid-bed type hopper vertically partitioned by a porous member to define therein an upper fluidizing container and a lower air chamber, and includes temperature/humidity control means for adjusting a temperature and humidity of compressed air supplied to said air chamber and means for stirring said powder in said fluidizing container; and wherein said pulverizing and dispersing means comprises a powder flow passage defined between an inner surface of said nozzle tip and an outer surface of said diffuser which gradually narrows toward a nozzle opening. - View Dependent Claims (3, 4)
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2. An electrostatic powder coating apparatus comprising a spray gun and a powder supply unit, wherein said apparatus is adapted to form a coating film by spraying electrostatically charged powder toward the surface of an electrically grounded product to be coated, and wherein said apparatus further comprises:
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a nozzle tip of said spray gun which includes means for dually functioning to pulverize and disperse a powder that has become aggregated and powder adhesion preventing means; wherein said powder supply unit comprises a fluid-bed type hopper vertically partitioned by a porous member to define therein an upper fluidizing container and a lower air chamber, and includes temperature/humidity control means for adjusting a temperature and humidity of compressed air supplied to said air chamber and means for stirring said powder in said fluidizing container; and wherein said pulverizing and dispersing means comprises a powder flow passage defined between an inner surface of said nozzle tip and an outer surface of said diffuser which gradually narrows toward a nozzle opening, and vortex air introduction ports through which vortex air is supplied to a powder flow passing through said powder flow passage. - View Dependent Claims (5, 6)
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7. An electrostatic powder coating apparatus comprising a spray gun and a powder supply unit, wherein said apparatus is adapted to form a coating film by spraying electrostatically charged powder toward a surface of an electrically grounded product to be coated, and wherein said apparatus further comprises:
a powder flow passage defined between an inner surface of an outer cylinder having a nozzle tip of said spray gun, said nozzle tip having an inner surface that gradually widens towards a nozzle opening, and an outer surface of a diffuser, said diffuser being located within said inner surface of said nozzle tip and said diffuser gradually widening toward said nozzle opening at a slightly greater rate than said gradual widening of said inner surface of said nozzle tip so that said powder flow passage gradually narrows towards said nozzle opening. - View Dependent Claims (8)
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9. An electrostatic powder coating apparatus comprising a spray gun and a powder supply unit, wherein said apparatus is adapted to form a coating film by spraying electrostatically charged powder toward a surface of an electrically grounded product to be coated, and wherein said apparatus further comprises:
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means for dually functioning to pulverize and disperse a powder that has become aggregated, wherein said pulverizing and dispersing means comprises a powder flow passage defined between an inner surface of an outer cylinder having a nozzle tip of said spray gun, said nozzle tip having an inner surface that gradually widens towards a nozzle opening, and an outer surface of a diffuser, said diffuser being located within said inner surface of said nozzle tip and said diffuser gradually widening toward said nozzle opening at a slightly greater rate than said gradual widening of said inner surface of said nozzle tip so that said powder flow passage gradually narrows toward said nozzle opening; and vortex air introduction ports through which vortex air is supplied to a powder flow passing through said flow passage. - View Dependent Claims (10)
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Specification