Apparatus for atomization in electrostatic coating and method

DETAILED DESCRIPTION In accordance with the present invention, an apparatus for atomizing liquid coating material for electrostatic deposition on an article comprises an annular housing rotatable about its axis.
The housing has a plurality of circumferentially spaced passages extending therethrough in a direction outwardly of its axis and an opening accommodating smooth introduction of coating material onto an inner surface thereof.
Upon rotation of the housing and introduction of coating material onto the inner surface the material flows under centrifugal force into and through the passages and is atomized as it is projected from and beyond the passages, with the passages constraining the material to the same rotational velocity thereas for improved atomization of the material.
In another embodiment, the apparatus comprises a cup-shaped housing having a circular frontal opening and a peripheral edge around the opening.
The housing is rotatable about the axis of the opening and accommodates introduction of coating material onto an inner surface thereof inwardly of the opening, whereby upon rotation of the housing coating material flows in a film under centrifugal force across the inner surface to the peripheral edge and is atomized as it is projected from the edge.
The apparatus is characterized in that first and second steps are formed in and circumferentially around the inner housing surface, the first step has a smooth surface and extends from the peripheral edge to a point inwardly thereof, and the second step extends from the first step to a point inwardly thereof and has a plurality of circumferentially spaced grooves formed in its surface generally along the direction of material flow.
Consequently, material introduced onto the inner surface of the housing flows across the surface to the second step, is projected onto the second step and flows through the grooves to the first step, is projected onto the first step and flows to the peripheral edge and is atomized as it is projected from the edge, with the grooves increasing the rotational velocity of the material toward that of the grooves for improved atomization of the material