Takayuki Kashima

A CO2 Gas Shielded Gas Tungsten Arc and its Application to Welding of Steel Sheets

In order to develop a novel welding process with low costs and high productivity in comparison with the TIG welding process, the characteristics of a CO 2 gas shielded gas tungsten arc (GTA) are studied. A double gas shielded system which consists of CO 2 gas and inert gas is employed for the GTA welding torch due to avoiding the consumption of tungsten electrode. The arc voltage of the CO 2 gas shielded GTA in the conditions of arc current 150 A and arc gap 3 mm is about 19 V which is much higher than 12 V of TIG arc in the same conditions. The CO 2 gas clearly constricts the arc and the maximum heat intensity at the surface of a water cooled copper anode in the CO 2 gas shielded GTA becomes about 10 times larger than that of TIG arc. Furthermore, the CO 2 gas shielded GTA has very good performance in the traveling speed for welding zinc coated steel sheets in comparison with the TIG welding process.

Characteristics of Plasma Flame in Metal-Cutting Apparatus of the Transferred-Type Plasma-Jet System

Studies were made of the characteristics of the plasma flame in trial-manufactured 60-to l00-kW metal-cutting apparatus of the transferred-type nitrogen plasma-jet system. First, the enthalpy of the plasma flame was measured, and the mean temperature was sought. Next, the line spectra radiated from singly ionized ions of nitrogen were utilized to measure the temperatures of the plasma flame. The maximum temperature was about 30 000°K. The speed of flow of the plasma flame was also sought using a high-speed streak camera. The maximum speed was approximately 5000 m/s.