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 Ta b l e 2 Comparative analysis of the results with the results obtained by the method based on toughness (KCV) Material The method of determining the maximum operability temperature based on impact toughness (KCV) (research by V. M. Kostiv D. S. Vasilega [1]) Authors ‘ methodology to determine the maximum operability temperature by changing the magnetic fi eld of eddy currents (research by the authors) В 35 (92 %WC+8 %Co) 520…730° С 460…730° С operability. This is con fi rmed by the study of the mechanics of the cutting process during the turning of the chromium-nickel alloy EI867-VD. The results obtained correlate with the results of research on increasing the service life of cutting tools, Table 2. The comparative analysis proves the possibility of using this technique to determine the maximum operability temperature of replaceable hard-alloy cutting inserts based on the study of changes in electromagnetic properties. The maximum allowable temperature of the interval is proposed as the resulting temperature since it provides the maximum service life of the tool and eliminates the possibility of its premature failure. Thus, changes in the electromagnetic properties of hard alloys for tools react to changes in the state of the material and can be used to determine the maximum operability temperature of replaceable cutting hard- alloy inserts. In production conditions, the cutting speed is easily determined according to this temperature range; the chosen speed provides the longest service life of replaceable cutting inserts using the method of a natural thermocouple or a thermal imager. Conclusion The research included experimental studies on changing the electromagnetic fi eld of eddy currents arising in hard alloys of the B35 grade under the in fl uence of high temperatures typical of the cutting process. The experimental studies allowed obtaining a temperature range of 460...730 °C characterized by changes in electromagnetic properties. Studies also comprised testing the mechanics of the cutting during turning of hard-to-process chromium-nickel steel EI867-VD at different cutting modes (speeds) by cutters equipped with replaceable cutting B35 hard-alloy inserts. These studies allowed fi nding the cutting speed that ensures the maximum service life of the cutting tool. The study showed that for turning the chromium-nickel alloy EI867-VD, the cutting speed of 18 m/min provides the maximum service life of the tungsten hard alloy B35. This is con fi rmed by the minimum value (0.225 mm) of the wear chamfer on the fl ank surface of replaceable cutting plates, and the minimum value of the relative surface wear on the fl ank surface h rsw 211.97 μ m/10 3 cm, obtained at a cutting temperature of 730°C. This temperature is included in the temperature range obtained in the laboratory when studying changes in the electromagnetic fi eld of eddy currents occurring in hard alloys of the B35 brand. Thus, these studies on measuring the structural changes of hard alloys enable identifying cutting speeds that ensure each hard alloy’s maximum service life or maximum operability based on a scienti fi c methodology. References 1. Artamonov E.V. Prochnost’ i rabotosposobnost’ smennykh tverdosplavnykh plastin sbornykh rezhushchikh instrumentov [Durability and working capacity of retro fi ttable hard alloy blades of assembly cutting tools]. Tyumen, Vektor Buk Publ., 2003. 190 p. ISBN 5-88465-416-2. 2. Zorev N.N., Uteshev M.H. Untersuchung der Kintakt-spannunger auf den Arbeits- fl achen des Werkzeugs miteiner Schneidenabrundung. Berichte der Internationalen Forschungesgemein-schaft fur mechanische produktionstechniktionstechnik , 1971, vol. 20-1, pp. 31–32.