The invention relates to a powder sprayer with electrostatic charging capacity and by means of which in a simple and effective manner by way of example a coloring powder can be electrostatically charged, so that it will be completely charged all over the entire surface of the particles. The powder sprayer (1) comprises a number of curved charging ducts (6, 6') of long extension made of electrically non-conducting material which ducts are coated with an electrically conducting layer (7) along the main portion of their extension, said coated layer (7) being connected to a conductor (8, 10) intended by way of example to be connected with the ground, whereby a charging of the powder material takes place during its movement through said charging ducts (6, 6') after contact with the inner walls of the ducts (6, 6'), when the sprayer is in use.
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.
A hand held powder spray gun is disclosed. The spray gun includes a casing enclosing a plurality of helical charging ducts mounted on parallel cores. The ducts receive powder from a diffusor mounted in a depending gun handle and discharge charged powder towards a nozzle mounted at one end of the casing.
A powder spray gun for applying particulate powder material onto a surface includes a gun body having a venturi transfer pump which receives air-entrained particulate powder material from a supply conduit and distributes the powder for discharge into a discharge conduit connected to the gun body. A spray head formed with a powder discharge slot is mounted to said discharge conduit. The discharge conduit is formed with a bend, preferably of about 90.degree., to concentrate the powder material along an outer wall formed by the bend for delivery in a concentrated stream to the spray head. A deflector is preferably mounted within the discharge conduit to direct the concentrated powder stream into the spray head in a predetermined manner. The powder discharge slot, which has a predetermined width and is formed by angled side walls meeting at an apex, receives the concentrated powder stream from the discharge conduit and sprays the powder in a wide, uniform spray pattern onto a surface.
An apparatus for applying a coating of solid particulate powder to the interior surface of tubular, cylindrical articles includes a conveyor for transporting the articles to and from a powder spray station whereat powder is sprayed into one open end of the articles. The conveyor includes an endless belt conveyor movable in a direction perpendicular to the spray from the nozzle and the axes of articles supported on the conveyor. The articles are supported on the conveyor by lugs in the form of rollers which support the articles in grooves defined between adjacent pairs of lugs.
A frictional electrification gun for use in electrostatic painting which can electrostatically charge power paint to a sufficient degree without the need of an elongated and twisted charging portion made up of nonconductive resin tubes. At the inlet of the charging portion made up of nonconductive resin tubes is provided a pre-charging portion for dispersing and charging powder paint. It has a nonconductive resin ring through which powder paint is fed swirling along its inner surface. The paint is thus sufficiently charged.
