Development of the Space Gas Hollow Tungsten Arc Welding Process for the Space Development of the World

1993年，我们提出了一种独特的、安全的空间GHTA（气体空心钨弧焊）焊接技术，可以在真空中进行。我们开展了该技术的空间应用研究和开发。建立了空间环境压力10^<-5> Pa下安全可靠启动电弧放电的技术和真空去除铝合金熔池氧化膜的技术。因此，我们能够在本研究中建立应用空间GHTA焊接的基础技术。采用直流高压启动法和触摸启动法启动电弧的现象焊接电弧星采用高频启动法可能会因电磁噪声而成为放置在空间站上的电气设备的障碍。因此，我们利用空间GHTA焊机在ISS轨道前，采用直流高压启动法和触摸启动法对铝合金进行了焊接启动实验。结果表明，在真空条件下，铝合金的电弧启动是可行的，并阐明了这些电弧启动的特点。研究了直流高压和触摸两种起动方式中焊接参数对电弧起动现象的影响。我们证实触摸启动方式在性能、重量、安全性等方面都优于直流高压启动方式。铝合金熔池氧化膜的焊接现象及去除机理研究发现，在真空条件下，逆变控制脉冲直流GHTA焊机可以去除铝合金熔池氧化膜。通过高速摄像机的观察，阐明了氧化膜的去除机理。我们还证明了在铝合金对焊接头上提供填充焊丝在去除氧化膜的情况下焊接，具有足够的强度。少

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 methodThe 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 … More 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 phenomenaWe 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 alloyWe 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