| Project/Area Number |
15560634
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | Takamatsu National College of Technology |
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Principal Investigator |
SUITA Yoshikazu Takamatsu National College of Technology, Department of Electro - Mechanical Systems Engineering, Professor, 制御情報工学科, 教授 (20044050)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2003: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | Space Welding / Space GHTA Welding / GHTA Welding / Space Station / Aluminum Alloy / Arc Discharge / Welding Phenomenon / Arc Start |
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| Research Abstract |
In 1993, we proposed a unique and safe space GHTA (Gas Hollow Tungsten Arc) welding technology which can be performed in a vacuum. We carry out the research and development for the space applications of this technology. We established the technologies which safely surely start the arc discharge at space environmental pressure 10^<-5> Pa and technology which removes the oxide film on the molten pool of aluminum alloy in a vacuum. As a result, we were able to establish the basic technology for applying the space GHTA welding in this research.
1. Phenomena of arc start by DC high-voltage starting method and touch starting method
The high-frequency starting method which was employed for the arc star of welding may be obstacle for electric devices placed on the ISS due to electromagnetic noise. Therefore, we conducted the start experiments of welding on an aluminum alloy by the DC high-voltage starting method and touch starting method with the space GHTA welding machine at the ISS orbital pre
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ssure. The arc starts of welding on aluminum alloy were shown to be possible by use of these starting methods, and the characteristics of these arc starts in a vacuum were clarified.
2. Effects of welding parameters in DC high-voltage and touch starting methods on arc starting phenomena
We investigated the effects of the welding parameters in these starting methods on the starting phenomena. We confirmed that the touch starting method excels the DC high-voltage starting method in performance, weight, safety.
3. Welding phenomena and removal mechanism of oxide films on molten pool in aluminum alloy
We discovered that the oxide films on molten pool in aluminum alloy could be removed by using the inverter-controlled pulsed DC GHTA welding machine in a vacuum. The removal mechanism of oxide films was clarified by the observation with high-speed video camera. We also demonstrated that the butt welding joints on aluminum alloy welded by supplying a filler wire under removing the oxide film, having the enough strength. Less
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