| 摘要 |
An electron gun mounted on top of a vacuum chamber, the gun emitting an electron beam vertically downward towards a substrate placed upon a three axis movable stage, creating a molten pool on the substrate, which is translated along an automatically generated, pre-programmed path in a plane normal to the beam by an automated numerical controller. A wire feeder and spool surround the beam in an annular ring, providing continuous material feed and constant orientation of the wire to the beam and pool, producing a high rate of material deposition and near net shape geometry. Integrated machining and inspection heads sequentially machine each layer to net shape then non-destructively inspect each layer. A heat and microstructure management system employs chilled oil or liquid metal coolant circulating through a vat surrounding the movable stage, supported by an actuator that gradually submerges the substrate as the deposited layers grow, the circulating coolant removing heat and machine chips. An integrated system architecture including six subsystems ensures density (no voids), accuracy, reliability, repeatability and verifiability: an energy management system manages energy input, including beam density, diameter and position; a geometry acquisition and path planning system acquires the cross-sectional two dimensional geometry from a three dimensional computer generated mathematical model and computes numerical control paths for deposit, machining and inspection processes; a material deposition system controls the placement and rate of material deposited; an integrated machining system subtracts excess material from each layer; an inspection and repair system detects, removes, refills and remachines defective areas; a heat management system eliminates excess heat by controlling the temperature and flow of a liquid metal coolant, and improves the microstructure of the deposited material via transducer generated sonic frequencies; a supervisory control synchronizes and coordinates the interaction between the various subsystems.
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