Installation for electrostatic deposition of powder on objects

In an installation for electrostatic deposition of powder on continuously travelling objects, said installation comprising:

• a conveyor,
• an elongated object treatment cage extending longitudinally and having a slot within the top of said cage extending throughout the length of said cage, an opening within one end of the cage forming a side entrance aligned with said slot and an opening within the opposite end of said cage forming an exit,
• said conveyor being positioned vertically above said cage, aligned with said slot and bearing hangers extending through said slot for supporting objects movable through the treatment cage from said entrance to said exit,
• a filtering system for removing excess powder from the air used in the coating operation,
• a system for supplying powder for electrostatic deposition and compressed air, and
• a tank for recovery of powder,
• the improvement wherein said cage comprises at least two, side-by-side modules, namely a first module and at least one second module having an end including a said cage end opening, said first module comprising means for storing and recovering powder and further containing means for projecting a mixture of powder and air onto the objects to be processed when within said first module, an opening between said first module and said second module aligned with said side entrance and exit and permitting said objects to be conveyed from said second module to the interior of the first module, and said at least one second module comprising;
• laterally spaced vertical walls defining a central passageway extending longitudinally over a portion of the length of said at least one second module with said passageway aligned with said entrance opening, air lock means, first filtering means, and a blower for drawing air and excess powder from said first module into said second module, for passage through said first filtering means for filtering excess powder, and for feeding air to said air-lock means to create an air lock at an air pressure in excess of atmospheric adjacent the end of said second module at said cage end opening such that air loaded with powder originating from said first module is prevented from escaping through said cage end opening and is filtered and recycled to said first module for further employment in the projection of powder onto the objects to be processed with said filtered air at a higher pressure than atmospheric so as to flow back through said central passageway towards said first module to prevent powder from escaping through said cage end opening.