| 摘要 |
<p>In this method, both plasma gas (PG) and protective gas (SG) are used. The entire workpiece thickness is penetrated by the plasma jet. Weld metal held in place by surface tension forces, flows together to form the seam. The novel feature is repeated variation in the gas flow(s) resulting in dynamic pressure variation on the melt, causing it to oscillate. An additional focus gas (FG) causes further constriction or necking of the plasma gas, both of these gases being surrounded by the protective gas. Volumetric flowrates of the plasma gas (VSpg), the focus gas (VSfg) and/or the protective gas (VSsg) are varied over time. These gases are each selected from argon, helium, nitrogen or hydrogen or their mixtures. The volumetric flowrates of plasma gas and focus gas are varied synchronously or out of phase, over time. The welding current is pulsated. Each period is composed of an impulse- or high current phase and a base- or lowest current phase. Volumetric flowrates of plasma gas and/or focus gas are varied in synchronism or out of phase with the current pulse profile. Variation of the gas volumetric flowrate with time, is described at least partially by a square wave.</p> |
