A plurality of paint spray guns are directed substantially perpendicularly toward respective vertically divided surfaces of a side panel of a workpiece such as an automotive body. The paint spray guns are spaced in a direction in which the workpiece is delivered and being disposed at different heights, respectively. Paint sprays are ejected from the paint spray guns toward the workpiece which is being delivered in the direction. Simultaneously, the paint spray guns are displaced back and forth perpendicularly to the direction and substantially parallel to the surfaces of the side panel to coat the surfaces respectively with the paint spray guns, thereby coating the side panel.
A coating or spraying gun is so disposed as to be movable back and forth in a given direction of travel of the member to be coated, including a body of an automotive vehicle, and to reciprocate in a direction different from the direction of travel of the member. The reciprocating stroke of the coating gun is altered depending upon the length of the member in the given direction. By altering the speed at which the coating gun moves back and forth in the direction of travel in accordance with the length of the member in the given direction, a pass pitch of the coating gun can be made constant. A coating region of the member is divided into coating sections or blocks in the given direction, and the sections are coated one after another. In this case, the reciprocating track of the coating gun is altered in accordance the radius of curvature of the sections. This arrangement enables a portion of a complex shape, such as a pillar, to be coated by moving the coating gun along the complex shape of the portion.
A rotary atomizer applies particulate paints with good color matching by reducing paint droplet size deviation and then optimizing the other paint spraying parameters. Paint droplet size parameters are reduced by using a bell cup having reduced flow deviations, including an overflow surface having a generally constant angle between a deflector and an atomizing edge.
