Optimization of plasmotron construction for surface modification of steel products

A technique for calculating the design parameters of an indirect action plasmotron for surface modification of complex shape parts has been proposed. The plasma modification process parameters characteristics, their mutual influence, the possibility of regulation have been given. The qualitative parameters of the plasmotron are influenced, first of all, by the parameters due to which the plasmotron is formed – arc current, the kind of the plasma-forming gas and its flow rate, the speed of the plasmotron movement and the parts. The diameter of the plasmotron channel and the nozzle apertures provide compression and stabilization of the plasma arc. The length of the channel and the distance to the surface being treated provide the maximum thermal efficiency and plasma temperature. The outer dimensions of the plasmotron are obtained from its design, proceeding from the necessity to be sufficiently cooled. It is necessary to take into account not only the requirements imposed on the hardened workpiece surface, but also on the mutual influence of these parameters. When changing the hardening parameters, it is important to save the service life of the plasmotron. This is possible with the correct choice of the cooling mode. A calculation of the liquid flow rate through the cavity of the plasmotron that is necessary to fulfil the given conditions and secure the proper heat exchange has been made. Tests of plasmatrons of various designs. confirmed the data of the calculations