| Abstrakt: |
Results of mathematical modeling of an argon arc with refractory cathode in case of a deformed surface of the weld pool (arc anode) are described. It is assumed that there is a depression (crater) on the anode surface, the shape and size of which are preset; arc plasma has axial symmetry, and it is in a stationary state; metal evaporation from the anode surface is ignored. A mathematical model of the processes of energy, momentum, mass and charge transfer in the arc column and anode region is briefly described. A numerical study was conducted of thermal, electromagnetic and gas-dynamic processes in the arc column with a curved surface of the anode, as well as conditions of electric, thermal and force interaction of the arc with the anode surface, depending on the crater depth. Results of computational experiments are illustrated by the fields of isotherms, isobars and current lines in an arc with a curved surface of the anode, which are compared with similar fields in the case of an anode with a plane surface. A procedure for calculation of normal components of the vectors of electric current density and specific heat flux into the anode with a curved surface is described, and results of calculation of radial distributions of these characteristics, depending on the depth of the crater on the anode surface, are given. These results are complemented by numerical studies of the influence of the crater depth on arc pressure distribution over the anode surface. A conclusion was made that sagging of the weld pool surface in TIG welding can significantly change the conditions of electric and thermal interaction of the arc with the metal being welded, namely it can influence the thermal and hydrodynamic processes in the liquid metal, which determine the penetrability of the arc with the refractory cathode. [ABSTRACT FROM AUTHOR] |
