Continuous powder feed system for maintaining a uniform powder coating thickness on objects being coated by electrostatic fluidized beds

A continuous powder feed system for feeding powder to and removing it from the coating bed of an electrostatic fluidized bed coating unit of the type wherein an object to be coated is passed through a cloud of electrically charged particles located above the fluidized powder bed, such as to maintain an essentially uniform powder cloud above the bed comprising:

• a. a powder container and discharger means for continuously feeding powder into said coating bed in an essentially non-agglomerated form;
• b. means for channelling the powder entering the coating bed away from the coating area initially to facilitate optimum electrostatic charging of the powder prior to deposition;
• c. powder retaining wall means for containing the bed of said coating unit during fluidization comprising a plurality of powder retaining walls, at least one of said powder retaining walls having a height such as to determine the powder level in the coating bed and permitting a uniform overflow of excess powder from the coating bed across the length of said at least one of said powder retaining walls;
• and
• d. a powder collection system for retrieving the overflowing powder from the coating bed.