A powder spray gun includes a rotary distributor which is capable of operating at slower speeds than liquid spray gun to reduce the problem of powder fusing, increases bearing life, reduce wear on moving parts. The powder spray gun has a powder flow path which extends through a gun body to a powder outlet. The rotatable powder distributor is located at the powder outlet. A drive mechanism in the form of a pneumatic motor is located within the housing and connected to the distributor the rotate the distributor. A spindle, which is mounted for rotation within the body, has a passageway therethrough which forms a part of the powder flow path. The distributor communicates with the passageway and is attached for rotation with the spindle. The powder thus enters the passageway in the rotating spindle before it passes into the rotating distributor. A chamber is formed within the body around the spindle, and the chamber is connected to an air supply to pressurize the chamber. A nonrotating flow tube through which powder flows into the passageway in the spindle, with a gap being formed between the nonrotating flow tube and the rotatable spindle. The gap communicates with the chamber whereby pressurized air from the chamber escapes through the gap to provide a rotary seal between the tube and the spindle. A sealing member may be used to prevent back flow of air through the gap.

An electrostatic spray coating assembly (10) for atomizing electrically conductive material comprises a rotary atomizer spray head (12) having an annular atomizing spraying edge (14). An external housing (22) supports the spray head (12) and a feed line (18) supplies the material from a supply system to the spraying edge (14) of the spray head (12). The feed line (18) and the material supplied thereby and the spray head (12) are electrically grounded. Three needle-shaped charging electrodes (36) are in spaced relationship circumferentially at uniform angular intervals with respect to the spray head (12). The charging electrodes (36) are connected to a source of high voltage potential for producing an electrical field charging the conductive material. The charging electrodes (36) are positioned from the spraying edge (14) of the spray head (12) a predetermined radial distance (R) at least twice the diameter (d) of the spraying edge (14) of the spray head (12).

A rotary atomizing electrostatic coating apparatus includes air feed passages connected to an air bearing, a turbine, and a shaping air cap, respectively. In any one of air feed passages, a divergence portion for causing a portion of air flowing in the one air feed passage to diverge from the one air feed passage is formed so that a diverging air flows into an interior of the drive shaft. As a result, it is not necessary to provide an additional, air feed passage and an air source therefor for preventing paint from entering a bearing clearance between the drive shaft and the air motor. As a result, a size of the apparatus will not be large and a cost of the apparatus will not substantially increase.

A rotational atomizer turbine of the present invention is designed to drive a bell-shaped disk in a rotational atomizer for a coating unit. The rotational atomizer turbine includes a housing, a rotatable turbine wheel with several turbine blades connected to a shaft and rotatably disposed in the housing. A plurality of nozzles are defined in the housing and are positioned relative the turbine wheel to drive fluid, i.e. gas onto the turbine blades. An intermediate chamber formed in the housing is fluidly communicated with and connected to the nozzles to hold gas therein. The intermediate chamber has a first inlet to supply gas. At least a second inlet is defined in the intermediate chamber for delivering gas into the intermediate chamber thereby increasing amount of gas therein to multiply a rotational speed of the rotatable turbine wheel as increased amount of gas is introduced to the turbine blades.

A method for matting a recording medium comprises supplying a humidifying gas stream onto the outer periphery of an atomized stream of fine droplets of an aqueous solution containing a matting agent by atomizing device along the atomized stream for affixing the fine droplets on the recording material, drying the liquid material in a drying chamber for forming micro-projections of the matting agent. Convex-shaped micro-projections of the matting agent, strongly affixed on the recording medium, are formed without contaminating the working environment.