OBRABOTKAMETALLOV Vol. 27 No. 1 2025 technology alloy indenter was soldered to the working end of the emitter. The indenter is a 6 mm thick plate in the shape of a circle segment with a diameter of 16 mm. The edge of the plate is rounded. The oscillating system was powered by a generator UZG2-22 (Afalina LLC, Moscow, Russia) with a maximum output power of 2 kW. The generator has automatic frequency control (AFC) and amplitude control functions, which allows changing the resonant frequency when the mechanical load at the end of the emitter changes. An electrodynamic vibrometer was used to measure the amplitude of oscillatory displacements ξm. This consists of a magnetic system comprising an annular permanent magnet (TU 48-1301-16–73), a measuring coil on a plexiglass frame containing 800 turns of PEV2-0.1 wire, and disc-shaped magnetic cores. The vibrometer was positioned on a waveguide of a rod oscillating system. To evaluate the maximum vibration amplitude ξm, the vibrometer was calibrated optically using a microscope. During operation of the oscillating system, the signal from the electrodynamic vibrometer was fed to a voltmeter, the scale of which was calibrated using the microscope. The specimen was secured in the lathe chuck on one end and supported by the lathe center on the other. To prevent the transmission of high-frequency vibrations to the chuck and center, they were equipped with PTFE (Teflon) vibration isolation pads. The lathe spindle speed was set to n = 560 rpm, which provides a processing speed of approximately Vr ≈ 1.2 m/s for the chosen specimen. Literature analysis [25, 26] and preliminary experiments indicate that changes in spindle speed have a negligible effect on changes in hardness and roughness. When varying the speed over a wide range, the roughness, with all other parameters held constant, changed by no more than 8–12 %, and the change in hardness did not exceed 10 %. Moreover, increasing the speed significantly increases the indenter temperature. Based on an analysis of SPD studies and preliminary experimental data, the following ultrasonic processing parameters were selected: longitudinal feed SX, oscillation amplitude ξmax and clamping force FN. For the given material and processing conditions, decreasing the feed rate Sx of the tool increases the technological effect, but significantly reduces the processing productivity. Therefore, a value of SX = 0.24 mm/rev was selected. The vibration amplitude was selected within the range of ξmax = 8–10 μm, since the most significant reduction in surface roughness is observed at these amplitudes. Increasing the clamping force above FN = 100–120 N does not lead to a significant result, so processing was performed at FN = 100 N. The study of the influence of the oscillating systems’ inclination angle on the properties of the deformed layer was carried out as follows: When processing the specimen according to the scheme shown in Fig. 4, the oscillating system with the working tool (indenter) was installed in the tool holder at an angle of α = 90° to the specimen surface in section 1. After processing section 1, the position of the oscillating system was changed by rotating the tool holder. During processing of section 2, the inclination angle α of the oscillating system was 75°; during processing of section 3 it was 60°, and during processing of section 4 it was 45°. Section 5 was retained as a control specimen. An example of processing the specimen sections at the oscillating systems’ inclination angles of 75° and 45° is shown in Fig. 5. Assessment of surface microgeometry The standard surface roughness parameters according to GOST 2789–73 were assessed on the control and processed samples: arithmetic mean deviation of the profile Ra, height of irregularities over 10 points Rz, maximum height of the profile irregularities Rmax, mean spacing of profile irregularities Sm, mean spacing of local peaks S, and relative bearing length of the profile tp, where p is the level of the profile section. The level of the profile section p was taken to be 30 % during measurements. The surface roughness parameters were measured on a profilometer Model 130 (Proton JSC, Zelenograd, Russia).
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