Determination of temperature of maximum operability of replaceable cutting hard-alloy inserts based on study of electromagnetic properties change

OBRABOTKAMETALLOV Vol. 23 No. 1 2021 TECHNOLOGY The resulting graphical dependence, where a polynomial is chosen as the approximating curve, is processed according to the rules of engineering research in accordance with the 5 % error allowed for such calculations. A special technique is used to determine the boundary of the temperature range. The 5 percent interval is laid off from the value of the maximum magnetic fi eld. A line parallel to the temperature axis is drawn through this point, through the entire fi eld of the graph. The points where the line intersects with the graph line are taken as the boundaries of the desired interval. From the obtained points, we draw projection lines on the temperature axis. The resulting temperature range is taken as the interval of the maximum service life of replaceable cutting inserts made of hard alloy B35. The tool can be used in the entire temperature range. However, from a technological point of view, it is preferable to adhere to the maximum temperature since it provides the maximum permissible cutting speed. Figure 6 shows the dependencies of the cutting temperature, the cutting path, and the relative surface wear of the tool. By the nature of these dependencies, we can say that in a certain temperature range there is a minimum of relative surface wear and a maximum of the cutting path, which proves the adequacy of the developed technique. Each point on the graphs represents the arithmetic mean of the obtained values, as a result, at least 3 measurements are carried out. Based on the obtained dependences (Fig. 6), the change in the EMF values direction corresponds to the structural changes of the fi rst phase transition of cobalt under laboratory conditions. Up to these values, there is an increase in the strength values of the hard alloy, which provides conditions for maximum tool Fig. 6. Dependencies of cutting temperature ( θ ), cutting path to failure ( L ), relative surface wear ( h tw ), cutting speed ( V ), (material to be treated EI867-VD (57 %Ni9 %Mo10 %Cr6 %W4,2 %Al4 %Co), tool material B35 (92 %WC+8 %Co), Feed ( S ) = 0,39 mm/n, Time ( t ) = 1 mm)