Fluid sprinkling – spraying – and diffusing – With means causing intermittent interruption of supply to...
Patent
1994-05-02
1995-12-19
Kashnikow, Andres
Fluid sprinkling, spraying, and diffusing
With means causing intermittent interruption of supply to...
B05B 708, B05B 716, C23C 412, B22F 908
Patent
active
054762227
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to metal spraying apparatus and is concerned with apparatus for spraying a coating of metal particles on to the surface of a workpiece.
2. Description of the Prior Art
U.S. Pat. No. 4,064,295 to Alfred R. E. Singer discusses a stream of gas atomized particles that moves past a secondary gas stream towards a substrate. The secondary stream is directed in an oscillatory manner against the stream of atomized particles to deflect the latter such that the particles are distributed in a controlled manner over the surface of the substrate.
SUMMARY OF THE INVENTION
According to the invention there is provided metal spraying apparatus comprising means for producing a stream of molten metal particles, a plurality of sets of gas nozzles arranged to direct a flow of gas at said stream in a direction inclined at an acute angle to the axis of said stream to deflect the flow laterally, and valve means for controlling cyclically the timing and quantity of gas supplied to the gas nozzles to cause the particle flow to move cyclically to and fro laterally, said sets of gas nozzles including two sets disposed at diametrically opposite sides respectively of the axis of the particle stream, and said valve means being arranged to control the supply of gas under pressure to the nozzles of the said two sets, characterized in that the valve means supplies gas to the two sets of nozzles through respective flow passages the effective cross-sectional area of each of which varies between zero and a maximum.
According to a preferred feature of the invention the effective cross-sectional area of the flow passage to each of the two sets in turn increases from zero to said maximum and decreases back to zero, the said area of each flow passage commencing to increase after the said area of the other flow passage has decreased to zero.
In one construction according to the invention, the valve means comprises a cylindrical rotor mounted for rotation in a cylindrical bore in a stator, the rotor having for each set of nozzles a circumferentially extending groove the radial cross-sectional area of which varies in a predetermined manner, and the stator element having inlet ports connected to be supplied with gas and outlet ports circumferentially aligned with the inlet ports respectively, the inlet and the respective aligned outlet ports being aligned with the respective grooves in said rotor whereby gas flows from each inlet port to the associated outlet port by way of one of the circumferentially extending grooves in the rotor. Conveniently, the cross-sectional area of said circumferentially extending groove varies stepwise.
In another construction according to the invention, the valve means comprises a hollow cylinder rotor mounted for rotation in a cylindrical bore in a stator, the interior of the rotor being connected to be supplied with gas, and the rotor having for each set of nozzles a circumferentially extending slot the axial width of which varies in a predetermined manner, and the stator having for each set of nozzles an outlet port communicating with the set of nozzles and being axially aligned with the slot associated with the same set of nozzles, each outlet port having an axial width equal to or greater than the widest part of the slot.
The total area of each set of nozzles may be equal to or less than the maximum effective area of the outlet port supplying gas to the set of nozzles, whereby the nozzles impose a limit on maximum flow of gas therethrough for a given gas supply pressure.
The apparatus may further comprise an accumulator chamber in permanently open communication with the respective ducts conveying the gas supply from the valve means to the sets of gas nozzles. Preferably the volume of said accumulator chamber is adjustable. The provision of the accumulator chamber has a substantial smoothing effect on the changes in the volume of air delivered to the nozzles corresponding to changes in the dimensions of the grooves in the rotor. By continu
REFERENCES:
patent: 3937252 (1976-02-01), Ishida
patent: 3941154 (1976-02-01), Bishop
patent: 4060117 (1972-01-01), Clark et al.
patent: 4064295 (1977-12-01), Singer
patent: 4508620 (1985-04-01), Najima et al.
Jenkins Walter N.
Singer Alfred R. E.
Kashnikow Andres
Sprayforming Developments Limited
Weldon Kevin
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