Influence of Technological Parameters of High-Precision Plasma Cutting on the Position of the Anode Spot on the Cut Edge

Abstract

The paper is devoted to investigating the position of the anode spot on the cut edge during high-precision plasma processing and studying the trajectory of the melting products flowing from the cut edge. The material of samples is structural steel of St3 (<strong>GOST 14637-89)</strong> having the thickness of 3, 4, 5, 6 and 8 mm. The formation of the cut edge was carried out according to the HiFocus technological scheme of cutting by using the equipment manufactured by the Kjellberg firm (Germany). It was found that among technological parameters such as current, cutting speed, pressure and flow rate of cutting and swirl gases considered in the paper the greatest influence on the position of the anode spot on the cut edge is made by the cutting speed. For the investigated technological scheme of cutting the ratio between the anode spot and the thickness of the cut material lies in the range from 0.42 to 0.47. The optimization of the processing speed is based on studying the trajectory of the melting products outflow from the cut edge.

Determining the processing modes of the low carbon steel by high-precision plasma cutting based on dimensionless complexes

“…The limit value of pressure and gas rate is determined by the chosen size type of a set of the plasmotron changeable parts. So, in determining technological parameters which influence the forming of the cut sides, it is possible to consider only the cutting speed as a controlling parameter [14,15]. At the preliminary stage before the description of the process, a number of experiments were conducted for determining the optimal value of the cutting speed at which the value of deviation from the cut perpendicularity is close to zero.…”

Detecting patterns of structure formation at various types of metal machining

“…As shown in paper [6], quality of the separating plasma cutting is characterized by the cut width, the magnitude of the non-perpendicular character of the lateral surfaces of the cut cavity, the roughness of the latter, the existence and size of a lattice, etc. From the point of view of thermophysics, the separating cutting of metals is the process of local heating, melting, and blowing of a metal from the frontal edge of the cut under exposure to the high temperature plasma jet [6]. In this case, the heat flow into a metal is predetermined by the radiant and convective heat exchange from the arc column, the arc spot, and a plasma jet behind the arc spot.…”

“…The disadvantages of these studies are the lack of examining the impact of process parameters on structural transformations in the cutting zone. Research reported in [5][6][7][8][9] was also aimed at determining the influence of technological characteristics of the process on such quality indicators as the width of cutting and a thermal impact zone.…”

“…The above indicators of thermal cutting quality are certainly important for determining the efficiency of a metal machining process. However, the process of metal crystallization after cutting is accompanied by many undesirable phenomena, including the formation of chemical heterogeneity [6,7], which exerts significant effect on the performance characteristics of the material being cut. The formation of cutting edges is also characterized by the depth of a thermal impact zone and structure formation in this zone after thermal cutting.…”

“…This necessitates subsequent machining of a material and affects the resulting cost of articles. The microscopic chemical heterogeneity, which emerges in a thermal cutting zone, is defined primarily by the character of primary crystallization of steel and depends on the amount and nature of alloying elements, impurities, and cooling conditions [5][6][7][8]. Therefore, it is important to study the influence of parameters for different methods of thermal cutting on regularities of structure formation for steels of varying degree of doping.…”