Apparatus for coating workpieces electrostatically

DETAILED DESCRIPTION AND ADVANTAGES The subject invention comprises an apparatus or electrostatically coating workpieces with an electrically conductive coating material The apparatus comprises a spraying device having a rotary atomizer, an external housing fabricated from an insulating material, and an internal housing disposed within the external housing.
The rotary atomizer includes a spraying head extending from the internal housing.
A supply line conducts the coating material from a storage system to the spraying head.
The supply line and the spraying head are at ground potential.
Needle-shaped charging electrodes having exposed front ends are distributed radially about the spraying head and are connected to a high voltage supply for charging the coating material and producing an electric field An electrode-holding arrangement is made of an insulating material for encasing the charging electrodes.
The electrode-holding arrangement includes at least one support extending from the external housing.
The apparatus is characterized by including potential control means for approximating the radial potential pattern between the internal housing and the charging electrodes to the radial distribution of the coating material sprayed.
The subject invention provides an apparatus which reduces the possibility of coating material contamination about the atomizer housing and the charging electrodes