METHOD AND APPARATUS FOR ELECTROSTATICALLY CHARGING WORKPIECES FOR SPRAY COATING APPLICATION

摘要

Disclosed herein are a method and apparatus for progressively charging an electrically isolated conductive workpiece from ground potential to high potential while the workpiece is supported by a moving grounded conveyor. A portion of the conveyor is selectively included in circuit with a high voltage source and a voltage divided to charge the isolated conveyed workpieces to high electrostatic potential with respect to ground. The highly charged workpieces are conveyed past a grounded spray device dispersing atomized particles (i.e., liquid or powder) which are at electrical ground potential. In accordance with well known electrostatic coating principles, the particles are attracted to the high potential workpiece parts and adhere thereto. The high potential is applied to the workpieces through a "brush and commutator" apparatus which sequentially and gradually increases the charging of the workpiece from ground potential to a predetermined desired level for electrostatic spray deposition in a spray zone and thereafter sequentially gradually decreases the charge on the workpiece to ground potential after exiting the spray zone.