OBRABOTKAMETALLOV Vol. 26 No. 4 2024 TECHNOLOGY Fig. 1. Scheme of the reverse polarity plasma torch operation (a); the appearance of the plasma jet at start (b) and in the operating mode (c); an increase in the density of the “water mist” around the plasma jet (d); and the appearance of the cutting zone (d): 1 – plate; 2 – plasma jet; 3 – gas fl ow; 4 – starting arc; 5 – working arc; 6 – fl ow of plasma-forming and protective gas; 7 – nozzle; 8 – external nut; 9 – vortex fl ows of gas and plasma; 10 – swirler; 11 – water supply to the hollow electrode; 12 – supply of cooling water to the plasma torch body; 13 – water cooling channels; 14 – electrode; 15 – solenoid; 16 – inner casing made of PTFE; 17 – outer steel casing; 18 – “water mist” b c d e to the design features of the plasma torch, the water fl ow (13) fi rst passed through the nozzle and electrode, and then partially exited the torch body and partially entered the discharge chamber. Current was supplied to the electrode via a copper solenoid (15), which also generated a magnetic fi eld to focus the plasma jet and electric arc. The inner torch body (16), with water and air supply channels, was made of fl uoroplastic, while the outer body (17) was made of steel. The working electrode (14) and nozzle (7) were made of M1-grade copper (Cu-ETP). At the start of the process, the distance between the plasma torch and the plate was increased (Fig. 1, b), and after arc stabilization, it was reduced (Fig. 1, c). During cutting, the “water mist” around the plasma jet varied signifi cantly due to pressure pulsations in the discharge chamber (Fig. 1, c, d). A large amount of
RkJQdWJsaXNoZXIy MTk0ODM1