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 plant includes a self-oscillating circuit (SOC) and an instrument panel (a multi-voltmeter is used to measure the quantitative complex characteristics of changes in the EC (eddy currents) magnetic fi eld, and a digital thermometer was used to measure the temperature state during the entire experiment). The electronic part of the device is an electronic circuit consisting of two series-connected condensers, a resistance, a transistor, and a power supply. The SOC is made in the form of a self-transformer, as the excitation winding of an eddy current converter. The winding is coated to prevent the harmful effects of heating and the destruction of the winding itself. The samples were tested during heating of replaceable cutting inserts made of tungsten hard alloy B35, Fig. 4. The heating temperature range was chosen in accordance with the temperature regime of the cutting process during blade machining of hard-to-process materials. Thus, the heating was carried out in the range up to 1000  C. The heating itself was carried out by the gas- fl ame method manually. The studies stages were: the sample was heated, in our case, the sample is a replaceable cutting hard-alloy insert in the as-delivered state, then a magnetic fi eld was induced on the sample under study by a non-contact method. Changes in the values indicating internal changes in the hard alloy were recorded on the measuring device (voltmeter) of the developed plant. The results were displayed on the screen of a computer monitor. Results and discussion The experimental studies results were compiled in the tables where the corresponding values of the eddy currents magnetic fi eld induced in replaceable cutting inserts made of tungsten hard alloy B35 were indicated with an interval of 10  C. The polynomial dependences of the obtained data on the heating temperature were constructed using the capabilities of the mathematical apparatus of the MS Excel software, Fig. 5. The temperature range 12 of Fig. 5, in which experimental studies were carried out, corresponds to the temperature range characteristic of the cutting process. Fig. 4. Heating of replaceable hard alloy cutting insert: 1 – sample, replaceable carbide insert from hard alloy B35 (92 %WC + 8 %Co); 2 – heat- ing device Fig. 5. The obtained one-parameter dependence of change of EMF values under the in fl uence of temperatures during the experiment on replaceable alloy cutting insert В 35 (92 %WC + 8 %Co)