Abstract:
A diffuser (518) comprises a conduit having a cross-sectional area that increases in a direction fluid flow. In one embodiment, the diffuser is used to reduce the incidence and severity of flow fluctuations that occur in an electrostatic deposition apparatus. In some embodiments, the diffuser includes one or more flow control features. A first flow-control feature comprises one or more appropriately-shaped annular slits (520) through which fluid having a greater momentum than a primary fluid moving through the diffuser is injected into the "boundary layer" near the wall of the diffuser. A second flow control feature comprises one or more annular slits (548) or, alternatively, slots or holes that are disposed at appropriate locations around the circumference of the diffuser through which a portion of fluid flowing in the boundary layer is removed. Boundary-layer flow removal is effected, in one embodiment, by creating a pressure differential across such annular slit or slots. Among other benefits, such flow control features reduce any tendencies for flow separation of the primary fluid in the diffuser.
Abstract:
The invention relates to an apparatus (1) for the electrostatic application of synthetic powders which comprises means (2) adapted to create a suspension of powder, means (3) adapted to suck the powder from the suspension and mix it with air so as to reduce the concentration of the powders, a gun body (4), at least one nozzle (41) and a voltage generator (5) for ionising the powders, in which the aspiration device for the powders is an in-line Venturi tube (2).
Abstract:
The invention relates to a powder spraying device for electrostatic powder coating of workpieces. In order to achieve a particularly good powder particle charge, the powder spraying device (10) contains a chamber (1) into which a powder/air mixture (PL) is introduced crosswise to the spraying device (13) by means of a feed pipe (11). A ground electrode (5) and multiple high-voltage electrodes (7) are placed in the chamber (1). All electrodes (5, 7) are swept by purified air (RLE, RLH) in order to prevent powder deposits.
Abstract:
A spray gun for powder coating of a workpiece has a powder and compressed air delivery tube (16) comprising a first part (18) in or associated with a handle (12) of the gun and a second part (20) communicating with the first part and at an angle thereto for delivering the powder to a nozzle (40) of the gun, wherein the first part of the tube has a continuation beyond its junction with the second part to provide a space (28) where powder can collect to form a cushion of powder to facilitate flow of powder around the angle of the junction.
Abstract:
An apparatus (10) is operable to sequentially spray powder onto each workpiece (12) of a plurality of workpieces. The powder flows from an improved nozzle assembly (320) as a series of pulses. Accumulation of powder on surfaces (328 and 414) in the nozzle assembly (320) is retarded by conducting a flow of fluid (air) from a source of fluid pressure through openings in the surfaces in the nozzle assembly. Thus, a plurality of openings (366) are formed in a side wall (326) of the nozzle assembly to enable fluid to flow through the openings in the side wall into the flow path (344) of air and powder through the nozzle assembly (320) to retard accumulation of powder on an inner side surface (328) of the side wall. An inner deflector (332) has an end surface (414) which faces toward the workpiece (12) and on which powder tends to accumulate. A flow of fluid is conducted through openings in the end surface (414) of the inner deflector (332) to retard the accumulation of powder on the end surface of the inner deflector.
Abstract:
In a method of and apparatus for accelerating and pressurizing a fluidized stream of particulate material, e.g. for blast cleaning by ice particles, the stream flows through a constriction (30, 83) in a flow passage (22). A flow of blast medium is discharged from a blast nozzle (40, 70) at supersonic speed into the fluidized stream so as to form within the fluidized stream a flow front (47, 146) which is impenetrable by the fluidized stream and which cooperates with the constriction (30, 83) to form an effective nozzle for accelerating the fluidized stream. Grounding is provided controlling electrostatic charges for either better work effect or neutralization in unwanted or hazardous conditions, and safety pressure relief, blast intensity control, articulation and changement of final nozzles for effective operation are also provided.
Abstract:
An electrostatic spray gun comprises at least one external corona discharge electrode (11) positioned so as to charge a stream of particulate matter entrained in a gas flow. Where the stream of particulate matter leaves the gun, the gun comprises a metal tube (7) charged to the same voltage as the corona discharge electrode (11) and through which tube (7) the particulate matter must pass prior to passing the electrode (11). In a preferred embodiment (not shown here) the electrode takes the form of a deflector which turns the stream of particulate matter through about 90 DEG . The spray guns of the invention may be used for the spraying of hygroscopic materials such as sodium diacetate.