LOW FLOW ARC HEAD VACUUM WELDING

ON-ORBIT WELDING FOR EITHER ASSEMBLY OR REPAIR OF FUTURE SPACE STATIONS AND PLATFORMS WILL REQUIRE NOVEL APPROACHES TO THE DESIGN OF THE ARC-TYPE WELDING HEADS, TO ENSURE THAT THIS VERY SUCCESSFUL FORM OF METAL JOINING CAN BE APPLIED IN THE VACUUM OF SPACE. IN PARTICULAR, THE CLEAN WELDS ACCOMPLISHED USING THE TUNGSTEN INERT-GAS (TIG) AND PLASMA WELDING APPROACHES MAKE THESE COMMON AND FAIRLY WELL UNDERSTOOD TECHNIQUES HIGHLY DESIRABLE FOR SPACE APPLICATION. ALTHOUGH AIR CONTAMINATION IS NOT A PROBLEM IN SPACE, EXISTING COMMERCIALLY AVAILABLE TIG AND PLASMA WELDING HEADS REQUIRE LARGE INERT-GAS FLOW RATES (APPROX. 1-10 LITERS/MIN.) FOR ARC STABILITY. THIS GAS-CONSUMPTION REQUIREMENT IS UNACCEPTABLE FOR A PRACTICAL SPACE-BASED WELDING TECHNIQUE. A NOVEL METHOD OF LOWERING THIS GAS CONSUMPTION WILL BE DEVELOPED BY USING A HOLLOW CATHODE IN PLACE OF A SOLID TUNGSTEN CATHODE ELECTRODE TO REDUCE THE INERT-GAS FLOW REQUIREMENT TO APPROX. 0.02 LITERS/MIN. FOR WELD CURRENTS OF HUNDREDS OF AMPERES. ON-ORBIT WELDING FOR EITHER ASSEMBLY OR REPAIR OF FUTURE SPACE STATIONS AND PLATFORMS WILL REQUIRE NOVEL APPROACHES TO THE DESIGN OF THE ARC-TYPE WELDING HEADS, TO ENSURE THAT THIS VERY SUCCESSFUL FORM OF METAL JOINING CAN BE APPLIED IN THE VACUUM OF SPACE. IN PARTICULAR, THE CLEAN WELDS ACCOMPLISHED USING THE TUNGSTEN INERT-GAS (TIG) AND PLASMA WELDING APPROACHES MAKE THESE COMMON AND FAIRLY WELL UNDERSTOOD TECHNIQUES HIGHLY DESIRABLE FOR SPACE APPLICATION. ALTHOUGH AIR CONTAMINATION IS NOT A PROBLEM IN SPACE, EXISTING COMMERCIALLY AVAILABLE TIG AND PLASMA WELDING HEADS REQUIRE LARGE INERT-GAS FLOW RATES (APPROX. 1-10 LITERS/MIN.) FOR ARC STABILITY. THIS GAS-CONSUMPTION REQUIREMENT IS UNACCEPTABLE FOR A PRACTICAL SPACE-BASED WELDING TECHNIQUE. A NOVEL METHOD OF LOWERING THIS GAS CONSUMPTION WILL BE DEVELOPED BY USING A HOLLOW CATHODE IN PLACE OF A SOLID TUNGSTEN CATHODE ELECTRODE TO REDUCE THE INERT-GAS FLOW REQUIREMENT TO APPROX. 0.02 LITERS/MIN. FOR WELD CURRENTS OF HUNDREDS OF AMPERES.