Can surface treatment process and apparatus

Can bodies arranged on a conveyor belt and to be spray-treated from upwardly, downwardly and sidewardly directions are urged downwardly and prevented from floating off of the conveyor belt by the downwardly directed sprays having a higher fluid pressure relative to the upwardly directed sprays. The invention also comprises an apparatus for surface treatment of can-bodies comprising a tunnel accommodating a series of pre-wash, treatment and post-wash zones, an endless conveyor belt of an open rod work construction for carrying thereon inverted trimmed can bodies to be treated and travelling through said zones, and a plurality of upper and lower nozzles for respectively directing sprays of treatment liquid upwardly from beneath and downwardly from above the upper flight of said conveyor belt against the inner and outer surfaces of can bodies to be treated, and a plurality of fan-shaped flat type side spray nozzles for directing sprays of treatment liquid towards the centers of said can feeding sections, said conveyor belt having a plurality of partitions outwardly projecting from the outer surface of the endless conveyor belt and extending in the direction of travel thereof to form a plurality of can feeding sections to receive can bodies to be treated, each section having a width slightly greater than the diameter of the can bodies, said upper nozzles being full-cone or pyramid type spray nozzles, said lower nozzles being full-cone, pyramid or fan-shaped flat type spray nozzles, and the upper and lower spray nozzles being arranged in a plurality of pairs, paired upper and lower nozzles being coaxially aligned with each other, and said side spray nozzles being arranged in a plurality of pairs along each can feeding section, paired side spray nozzles being disposed at transversely symmetrical positions with respect to the center of the can feeding section and spaced apart from each other by a distance equal to or greater than the diameter of can bodies.