Method and apparatus for electrostatic coating of articles with powdered coating material
First Claim
1. An apparatus for electrostatic spraying of coating material on articles, the apparatus comprising:
- a feed channel having a first end through which the coating material is introduced into the feed channel and a second end through which the coating material emerges, the feed channel having at least one charging surface therein made of electrically insulated material suitable for electrically charging the coating material by friction;
at least one discharge electrode disposed at a location outside of the feed channel, the at least one discharge electrode including means for connection thereof to a predetermined electrical potential;
a gas channel extending between the at least one discharge electrode and the feed channel, the gas channel being suitable for enabling an electrically conductive gas to flow and contact both the at least one discharge electrode and the at least one charging surface in the feed channel, whereby the gas is effective for preventing coating material from reaching the at least one discharge electrode and also for providing an electrically conductive path through which electrical charges collected on the at least one charging surfaces are conducted to the at least one discharge electrode.
1 Assignment
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Accused Products
Abstract
A spraying gun for electrostatic spraying of coating material on an article contains a discharge electrode which is disposed entirely outside the region where the coating material flows. The coating material is accelerated through an annularly shaped and axially extending channel in which the coating material is electrically charged by friction between itself and the insulated walls that define the channel. A gas conduit extends from the discharge electrode and reaches into the annular feed channel of the coating material. Location of the gas conduit between the discharge electrode and the feed channel allows the gas flowing in the gas conduit toward the feed channel to serve the dual purposes of preventing coating material from flowing to and settling on the discharge electrode and providing an electrically conductive path through which undesired electrical charges which develop on the walls of the feed channel discharge to the discharge electrode.
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Citations
8 Claims
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1. An apparatus for electrostatic spraying of coating material on articles, the apparatus comprising:
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a feed channel having a first end through which the coating material is introduced into the feed channel and a second end through which the coating material emerges, the feed channel having at least one charging surface therein made of electrically insulated material suitable for electrically charging the coating material by friction; at least one discharge electrode disposed at a location outside of the feed channel, the at least one discharge electrode including means for connection thereof to a predetermined electrical potential; a gas channel extending between the at least one discharge electrode and the feed channel, the gas channel being suitable for enabling an electrically conductive gas to flow and contact both the at least one discharge electrode and the at least one charging surface in the feed channel, whereby the gas is effective for preventing coating material from reaching the at least one discharge electrode and also for providing an electrically conductive path through which electrical charges collected on the at least one charging surfaces are conducted to the at least one discharge electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification