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 based on the study of changes in the electromagnetic fi eld of eddy currents that occur in replaceable cutting inserts at a temperature change. To achieve the aim, the following tasks were set and solved. 1. To perform a literary review, as well as to analyze existing works devoted to the problems of rational choice of tool material, as well as the appointment of cutting modes. 2. To conduct experimental studies of changes in the electromagnetic fi eld of eddy currents arising in B35 hard alloys under the in fl uence of high temperatures inherent in the cutting process. 3. To research the mechanics of the cutting process during turning of hard-to-process chromium-nickel steel EI867-VD at different speeds with cutters equipped with replaceable cutting hard-alloy inserts made of hard alloy B35. Research Methodology The operability of cutting tools is considered to be the conditions under which they can perform cutting in accordance with the established requirements under certain conditions [21]. Solving the second task required conducting laboratory studies of changes in the magnetic fi eld of eddy currents arising in replaceable cutting inserts made of tungsten hard alloy B35. The experiment was carried out in the temperature range from room temperature to the temperature that occurs at the tip of the cutting edge during cutting. It is at such temperatures that the cutting process takes place when machining hard- to-process steels and alloys, such as EI867-VD. An analysis of existing solutions has shown that there are no such devices to meet our requirements. One of the requirements for the device is the possibility of using a replaceable polyhedral hard-alloy insert as a test sample in the as-delivered state for maximum approximation of the results to real conditions. A laboratory plant was built to conduct experimental studies. During the development of the laboratory plant, the literature review showed that methods of non-destructive testing of technological objects are widely used at the moment. These methods allow conducting studies of internal changes without destroying samples, which was a decisive advantage in the literary review. There are seven types of non-destructive testing, presented in Fig. 1 [22], each of them has both advantages and disadvantages. The non-destructive eddy current testing method is suitable for studies of internal changes occurring in tool materials [22]. It can also be applied for testing samples of replaceable cutting hard-alloy inserts (RCHAI) in the as-delivered state. This testing method is based on the analysis of the interaction of an external electromagnetic fi eld with the electromagnetic fi eld of eddy currents [23]. This advantage not only meets our requirements but also allows reducing the time for the production of special samples made of tungsten hard alloy B35. In addition, it makes laboratory tests similar to real conditions, which is undoubtedly a signi fi cant advantage over other types of non-destructive testing. Replaceable cutting hard-alloy inserts made of the tool hard alloy B35 in the as-delivered state were selected as the studied samples, Fig. 2. The characteristics of the selected replaceable cutting inserts are shown in Table 1. The research was carried out on a special laboratory plant and was based on the eddy current method of non-destructive testing. The scheme of the proposed plant is shown in Fig. 3. The laboratory plant is a system of devices for measuring changes in the magnetic fi eld of eddy currents arising in ferromagnets. RCHAIs in the as-deliverer state are recommended to use as objects of research since the size of the used coil with a heat-insulating coating is the limiting factor. When changing the coil, studies on samples of other form factors are allowed. Fig. 1. Types of non- destructive testing (NDT)