Conveyors: fluid current – Load flow diverter – divider – or combiner – Movable conduit section
Reexamination Certificate
2000-03-03
2001-10-23
Valenza, Joseph E. (Department: 3651)
Conveyors: fluid current
Load flow diverter, divider, or combiner
Movable conduit section
C406S085000, C406S107000
Reexamination Certificate
active
06305884
ABSTRACT:
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to solids fabrication processes, and more particularly to a feedthrough device for distributing gas entrained materials to a rotating head assembly, such as found within a solids fabrication system.
2. Description of the Background Art
Fabrication of three-dimensional solids is being performed within fabrication systems that build up a solid by layered fusing bits of material carried in a gas. One such system is a directed light fabrication (DLF) system. In a DLF system powders are injected into a moving beam of high power light, generally a laser light beam. The powders are typically metallic particles, however plastics and other fusible materials can be used. The powders are carried by a stream of gas, commonly argon, to the focal point of the laser beam wherein fusing of the material to the previous layer of material occurs. The gas provides a non-reactive carrier for the particles of the powder which are to be fused into a solid. In practice, the powder often gets injected non-uniformly about the beam resulting in a build-up of the fused powder material that is also of non-uniform structure. The flow of powder in the input feed lines may be adjusted to suit conditions required at the head, yet non-uniform injection may still occur. One contributing factor to the non-uniform injection of powders arises when the laser head and nozzles within a DLF system rotate. Conventionally, in order to accommodate head rotation, the input lines have been provided with an amount of slack in them. During rotational movements, the input lines are thereby subjected to a variety of movements which alter the distribution of gas entrained powder flow being emitted at the nozzles.
To achieve a uniform finished structure, therefore, it is important to reduce the disruptive gyrations of powder feed lines whereby increased uniformity of powder injection may occur. The rotary powder feed through apparatus in accordance with the present invention provides a coupling which satisfies the need to minimize feed line movements to the head, and overcomes additional deficiencies in current techniques for the coupling of gas entrained powder to a rotating head assembly.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a feed through coupling between a stationary set of input lines and a set of output lines which are rotating with the head within a solids fabrication system, such as a directed light fabrication (DLF) system. The feed through system thereby eliminates the need for slack supply lines, and the motions thereof, to accommodate the rotation. The gas entrained powder feed through of the invention can employ input and output lines that remain relatively fixed, the lines do not gyrate and flop about in response to head rotations, as they do not contain the slack in the tubing (hoses) which was required previously. Eliminating the gyrations of the feed tubes by the inventive system provides for improvement in the uniformity of the powder flow rate.
An object of the invention is to provide a rotational interface between a set of fixed input lines and a rotating nozzle head being fed with gas entrained powder.
Another object of the invention is to maintain even distribution of gas entrained powder through the rotary powder feed through.
Another object of the invention is to minimize flow restriction introduced by the rotary powder feed through according to the invention.
Another object of the invention is to provide a feed through mechanism that can be implemented to accommodate various numbers of feed lines.
Another object of the invention is to provide for free rotational movement of the fabrication head without interference from the interactions between feed lines.
Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.
REFERENCES:
patent: 3494175 (1970-02-01), Cusick et al.
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patent: 3837360 (1974-09-01), Bubula
patent: 4911340 (1990-03-01), Abom
patent: 5182430 (1993-01-01), Lagain
patent: 5207643 (1993-05-01), Davis
patent: 5277144 (1994-01-01), Moody
patent: 5601115 (1997-02-01), Broerman
patent: 5992453 (1999-11-01), Zimmer
patent: 5993554 (1999-11-01), Keicher et al.
Less Richard M.
Lewis Gary K.
Dillon, Jr. Joe
O'Banion John P.
The Regents of the University of California
Valenza Joseph E.
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