Electron Beam Source Layout for Contamination-Resistant 3D Printing
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Solution Overview
Problem
Additive manufacturing using electron beam sources is hindered by material evaporation and contamination, which can disrupt the manufacturing process and limit the choice of materials that can be used.
Innovation Solution
The implementation of an electron beam source with a rare earth metal hexaboride cathode and hydrogen gas in the vacuum chamber to prevent foreign particles from entering the electron beam column, maintaining a higher pressure in the second section to prohibit gas molecules and stimulate electron emission, allowing for the use of various materials regardless of their evaporation rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If materials with high evaporation rates are used in additive manufacturing with electron beam sources, then material selection freedom is improved, but electron beam source contamination increases
Solution Approach 1:
The vacuum chamber is divided into two separate sections: a first section for powder deposition and fusion, and a second section housing the electron beam source. This segmentation isolates the electron beam source from contaminated powder material, allowing high evaporation rate materials to be processed without contaminating the electron beam source.
Solution Approach 2:
A gas barrier (such as nitrogen or argon) is introduced into the first section to act as an intermediary layer between the powder material and the electron beam source. This gas barrier prevents direct contact and contamination while still allowing the electron beam to penetrate and fuse the powder through the gas medium.
2Reliability
If vacuum pressure is reduced to prevent contamination, then electron beam source stability is improved, but material evaporation control deteriorates
Solution Approach 1:
The vacuum chamber is segmented into two sections with different pressure conditions. The first section maintains higher pressure to control material evaporation, while the second section maintains lower pressure to protect the electron beam source. This segmentation allows both contradictory requirements to be satisfied simultaneously in different spatial zones.
Solution Approach 2:
Different vacuum pressure levels are applied locally to different sections of the vacuum chamber. The first section has higher pressure (10^-3 to 10^-1 Pa) for evaporation control, while the second section has lower pressure (10^-6 to 10^-4 Pa) for electron beam source stability. Each section has optimized local conditions for its specific function.
3Object-affected harmful factors
If gas pressure is increased in the electron beam section, then contamination prevention is improved, but electron beam generation quality deteriorates
Solution Approach 1:
The electron beam system is segmented into a high-pressure first section for contamination prevention and a low-pressure second section for beam generation. The gas barrier in the first section prevents contamination while the electron beam is generated in the evacuated second section, maintaining both contamination protection and beam quality.
Solution Approach 2:
A gas barrier is introduced as an intermediary medium in the first section to prevent contamination from reaching the electron beam source. The gas allows mechanical separation and contamination prevention while the electron beam penetrates through the gas-free or low-gas second section to maintain generation quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the stability of the manufacturing process by preventing contamination and allowing for a wider range of materials to be used, increasing the freedom in material selection and maintaining electron beam source integrity.
Implementation Method 1
The cathode in the electron beam source is made of a rare earth metal hexaboride. The gas is hydrogen gas for stimulating electron emission from the cathode.
Implementation Method 2
an energy beam source for delivering an energy beam spot to the powder whereby fusion of the powder takes place
Data Source
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AI summary
A method for forming a three dimensional article (3) through successively depositing individual layers of powder material that are fused together with an electron beam from an electron beam source (6) so as to form the article. Providing a model of said three-dimensional article; a vacuum chamber (20, 20a, 20b) having at least a first (20a) and a second (20b) section, powder material that are fused together is provided in said first section, the at least one electron beam source is provided in said second section, wherein said first and second sections are openly connected to each other. Directing an electron beam from said at least one electron beam source over said work table (2) to fuse in first selected locations according to said model to form a first cross section of said three-dimensional article while supplying a gas (from 46, via 44, 50) to said second section of said vacuum chamber.