Dispensing – Automatic control – Constant weight – volume or pressure control by output
Reexamination Certificate
1999-06-29
2001-07-10
Bomberg, Kenneth (Department: 3754)
Dispensing
Automatic control
Constant weight, volume or pressure control by output
C222S063000, C222S109000, C222S161000, C222S163000, C222S630000, C222S198000, C222S144500, C222S145100
Reexamination Certificate
active
06257447
ABSTRACT:
BACKGROUND
The present invention relates generally to devices to deliver powder for a process, and more specifically to a new class of powder feeders which deliver a wide range of powdered materials at a substantially constant rate.
Traditional powder feeders incorporate as part of their action the movement of powder between moving surfaces. Examples include screws, gear teeth, rotating perforated disks, or other such mechanisms which move the powder from a reservoir at a substantially constant rate. Tight mechanical tolerances are required so that such devices can provide a controlled feed rate, but these same tolerances render the device susceptible to jamming as powder collects in bearings or between moving surfaces. In addition, if hard or abrasive powders are to be delivered, the rate of wear of the mechanical components of the powder feeder can be unacceptably large. Wear is not only to be avoided for the survival of the powder feeder, but also to avoid contaminating the powder being fed. Alternately, overly soft powders can agglomerate and clog these mechanisms.
Jamming in conventional powder feeders is also exacerbated by feeding powder with a range of particle sizes. If the powder size is smaller than the separation between the moving metal surfaces in the feeder, it can collect, e.g., between bearing surfaces, causing damage and contamination of the powder by galling. If the powder size is too large, individual particles can jam and/or break the apparatus.
There is a need for a powder feeder which is robust in operation, and can supply a precisely defined and controlled delivery of powder. Desirable characteristics for such a powder feeder, based on the difficulties seen in prior art feeders, would include a minimum of moving parts, a delivery mechanism suited to feedback control of delivery rate, and a mechanism which does not undergo damage when the powder flow becomes jammed. More preferably, the feeder should possess a mechanism through which the feeder can be unjammed with a minimum of interruption.
SUMMARY
The present invention is of a precision powder feeder in which a powder falls from a powder reservoir through an orifice. The powder flow then impinges on a powder disperser, which can take the form of an inclined ramp. The flow then fans out into a cone-shaped sheet on said ramp. A powder collector is then moved in and out of the path of the sheet of powder, collecting that portion of the powder which falls into the collector and delivering it to the apparatus being served by the powder feeder. The collector position can be controlled by a feedback signal obtained from a powder mass rate sensor, thereby providing a constant rate of flow.
REFERENCES:
patent: 2273330 (1942-02-01), Robinson
patent: 2969893 (1961-01-01), Peeters
patent: 3308898 (1967-03-01), Allen et al.
patent: 4354622 (1982-10-01), Wood
patent: 5024352 (1991-06-01), Gmur et al.
patent: 5380957 (1995-01-01), Giles
patent: 5834707 (1998-11-01), Wirth
patent: 6094994 (2000-08-01), Satake et al.
Oliver Michael S.
Schlienger M. Eric
Schmale David T.
Bomberg Kenneth
Dodson Brian W.
Sandia Corporation
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