Vacuum fluidized-bed coating apparatus

Claim 1

A coating apparatus for applying a fluidizable coaTing powder to a workpiece which comprises: a sealed chamber, means for selectively evacuating said chamber, means for supporting said workpiece within said chamber and movable therein, an induction coil supported about said workpiece, a source of r.f. energy electrically connected to said induction coil, a container open at its upper portion and disposed directly below said workpiece, said container having a plurality of vane elements extending from the inner walls thereof, fluidizing means carried by said container for providing a fluidized-powder bed of the powder placed therein, said fluidizing means comprising a bladed impeller means horizontally disposed at the bottom of said container and rotatably supported on one end of a vertical shaft extending through said bottom, means to drive said impeller comprising a magnetic couple wherein one magnet is supported on the other end of said shaft within said chamber and a driving magnet is disposed externally of said chamber, and means to move said work support whereby said workpiece may be preheated at said induction heater, carried within said fluidized bed of powder for a coating application and subsequently moved back to said heater for a final heating treatment.