Powder feed pickup device for thermal spray guns
First Claim
1. A powder feeding system for a thermal spray gun, comprising:
- an enclosed hopper for a powder to be thermal sprayed in loose particulate form;
a feed gas conduit adapted to discharge a regulated amount of feed gas under pressure into the hopper; and
a carrier conduit for a carrier gas stream, connected to a carrier gas supply and extending to a point of powder carrier gas utilization;
the carrier conduit having a plurality of powder intake orifices communicating with the carrier conduit at a pickup location situated between the carrier gas supply and the point of utilization, the intake orifices extending into the hopper below the normal minimum level of the powder and having a geometric design and arrangement such that there is no gravity flow of powder therethrough into the carrier gas stream in the absence of a feed gas flow therethrough, wherein the axes of the intake orifices extend away from the carrier conduit at an acute angle to the axis of the carrier conduit with respect to the carrier gas stream.
3 Assignments
0 Petitions
Accused Products
Abstract
A powder feeding system for a thermal spray gun provides uniform control of powder feed rate with a minimum of pulsation during operation and without feeding during idle mode. The feeder is comprised of an enclosed hopper for containing a powder to be thermal sprayed, a carrier conduit connected between a carrier gas supply and a thermal spray gun, a feed gas conduit for discharging a regulated supply of feed gas under pressure into the hopper, and one or preferably more powder intake orifices extending from the carrier conduit into the hopper below the normal minimum level of powder. The intake conduits have a geometric design and arrangement such that there is no gravity flow of powder therethrough into a carrier gas stream in the absence of a feed gas flow therethrough. The axes of the intake orifices extend away from the carrier conduit at an acute angle to the axis of the carrier conduit as defined by the direction of carrier gas flow. Preferably there is a constriction in the carrier conduit downstream of the intake orifices.
29 Citations
25 Claims
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1. A powder feeding system for a thermal spray gun, comprising:
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an enclosed hopper for a powder to be thermal sprayed in loose particulate form; a feed gas conduit adapted to discharge a regulated amount of feed gas under pressure into the hopper; and a carrier conduit for a carrier gas stream, connected to a carrier gas supply and extending to a point of powder carrier gas utilization; the carrier conduit having a plurality of powder intake orifices communicating with the carrier conduit at a pickup location situated between the carrier gas supply and the point of utilization, the intake orifices extending into the hopper below the normal minimum level of the powder and having a geometric design and arrangement such that there is no gravity flow of powder therethrough into the carrier gas stream in the absence of a feed gas flow therethrough, wherein the axes of the intake orifices extend away from the carrier conduit at an acute angle to the axis of the carrier conduit with respect to the carrier gas stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A powder feeding system for a thermal spray gun comprising:
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an enclosed hopper containing a powder to be flame sprayed in loose particulate form; a carrier gas conduit connected to a carrier gas supply and extending to a point of powder carrier gas utilization, the carrier gas conduit having a plurality of powder intake orifices communicating with the carrier gas conduit at a pickup location situated between the carrier gas supply and the point of utilization extending into the hopper below the normal minimum level of the powder and having a geometric design and arrangement such that there is no gravity flow of powder therethrough into the carrier gas stream in the absence of a feed gas flow therethrough; and a feed gas conduit adapted to discharge a regulated amount of feed gas under pressure into the hopper at a point remote from a fluidized zone of the powder in the hopper in the immediate vicinity of the intake orifices; the hopper being adapted to cause the fluidizing gas to pass through the powder therein and converge towards the intake orifices and fluidize the powder in the immediate vicinity thereof, the powder surrounding the fluidized zone being non-fluidized and acting as a diffusing region for introducing fluidized gas uniformly into the fluidized zone;
whereinthe axes of the powder intake orifices extend away from the carrier conduit at an acute angle to the axis of the carrier conduit with respect to the carrier gas. - View Dependent Claims (19)
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20. A powder feeding system for a thermal spray gun, comprising:
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an enclosed hopper for a powder to be thermal sprayed in loose particulate form; a feed gas conduit adapted to discharge a regulated amount of feed gas under pressure into the hopper; and a carrier conduit for a carrier gas stream, connected to a carrier gas supply and extending to a point of powder carrier gas utilization, the carrier conduit having four powder intake orifices communicating with the carrier conduit at a pickup location situated between the carrier gas supply and the point of utilization, the intake orifices extending into the hopper below the normal minimum level of the powder and having a geometric design and arrangement such that there is no gravity flow of powder therethrough into the carrier gas stream in the absence of a feed gas flow therethrough;
whereinthe axes of the intake orifices extend away from the carrier conduit at an acute angle between about 30° and
about 70°
with the axis of the carrier conduit with respect to the carrier gas stream; andthe carrier conduit has a constriction therein located at a distance less than about 5 cm from the intake orifice closest to the constriction, the ratio of the cross-sectional area of the constriction to the average cross-sectional area of the carrier conduit at the pickup location being between about 0.1 and about 0.9. - View Dependent Claims (21)
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- 22. A powder feed pickup device for a thermal spray gun, comprising an elongated member having an axial bore therethrough adapted for connection within an enclosed powder hopper to a carrier conduit so as to direct a carrier gas stream through the axial bore, the elongated member having at least four powder intake orifices having intersections with the axial bore, the intake orifices adapted to extend into an enclosed powder hopper below the normal level of the powder and having a geometric design and arrangment such that there is no gravity flow of powder therethrough in the absence of any gas flow therethrough, wherein the axes of the intake orifices extend away from the axial bore at an acute angle with respect to the carrier gas stream, and the axial bore has a constriction therein at a location separated from the intake orifice intersections in the direction of the carrier gas stream, the ratio of the cross-sectional area of the constriction to the average cross-sectional area of the axial bore at the intake orifice intersections being between about 0.1 and 0.9.
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24. A method of feeding powder to a thermal spray gun, comprising the steps of:
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providing an enclosed hopper for a powder to be thermal sprayed in loose particulate form; extending a carrier conduit from a carrier gas supply to a point of powder carrier gas utilization; extending a plurality of intake orifices from a pickup location in the carrier conduit into the hopper below the normal minimum level of the powder, the extending being away from the carrier conduit at an acute angle to the axis of the carrier conduit with respect to the carrier gas stream, and the intake orifices having such design and arrangement that there is no gravity flow of the powder therethrough into the carrier gas stream in the absence of a feed gas therethrough; flowing a carrier gas stream from the carrier gas supply through the carrier conduit to the point of powder carrier gas utilization; and discharging a regulating amount of feed gas under pressure into the hopper. - View Dependent Claims (25)
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Specification