OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 4 No. 3 2022 is much greater, therefore, in further studies, tools equipped with inserts made of T15K6 alloy were not used. Fig. 2 shows the results of a study of the wear of carbide inserts T5K10 and VK8, where curve refl ects the dynamics of wear under normal cutting conditions (V = 10 m/min, t = 3 mm; Sl = 0.31 mm/rev); 2-2ʹ – during plasma-assisted machining (V = 20 m/min, t = 6 mm; Sl = 0.31 mm/rev; İ = 250 A; U = 150 V); 3-3ʹ – when cutting with plasma-ultrasonic-assisted machining (V = 20 m/min, t = 6 mm; Sl = 0.31 mm/rev; İ = 250 A; U = 150 V; f = 18 kHz; А = 4 μm): 1, 2, 3 – when machining with T5K10 grade hard alloy inserts: 1ʹ, 2ʹ, 3ʹ –whenmachining with VK8 grade hard alloy inserts. The wear of the inserts in the normal mode of machining was studied at V = 10 m/min, Sl = 0.31 mm/rev. When the cutting modes increase from the specifi ed value, the cutting tool loses its cutting ability within 2-3 minutes. Plasma-machining and plasma-machining with the use of ultrasound were carried out in the same mode of mechanical cutting. When processing high-temperature steel grade 20Cr13Ni18 under various cutting conditions, it was found that Т5K10 carbide inserts compared to VK8 wear faster on the back surface in all types of processing. It was revealed that when turning steel 20Cr13Ni18, both single-carbide carbide inserts and doublecarbide ones wear out signifi cantly more with the usual turning method than with other processing methods [16–23]. Results and discussion Analysis of the results obtained made it possible to fi nd out that during plasma-assisted turning of steel 20Cr13Ni18, despite the fact that the depth of cut is 2 times greater (curves 2, 2ʹ, Fig. 2) than during the conventional turning, (curves 1, 1ʹ, Fig. 2), wear of the end fl ank of the straight turning tool is 1.5–2 times less, subjected to the cutting speed. And during plasma-assisted machining with the use of ultrasound, the wear of inserts (curves 3, 3ʹ, Fig. 2) is 5–10 times less than the wear of inserts during conventional turning (curves 1, 1ʹ). For example, during conventional turning of high-temperature steel 20Cr13Ni18 with a T5K10 carbide insert for 5 minutes of cutting, wear of the insert is achieved within 0.5–0.6 mm (curves 1 in Fig. 2), and when turning the same steel by plasma-assisted machining using ultrasound, wear of the T5K10 cutter up to 0.4 mm is achieved within 52 minutes, which indicates a decrease in insert wear by 10 times. In the current study, fi ve experiments were performed to plot each point. Experiments have shown that, both with the conventional method and with plasma-assisted machining along the slag, turning tools equipped with VK8 single-carbide carbide inserts have a number of advantages compared to turning tools equipped with two-carbide carbide inserts. In particular, studies have shown that the nature of the wear of the end fl ank of the cutting edge of the VK8 hard alloy inserts is more uniform, the intensity and rate of wear are slowed down, no catastrophic damage is observed, which favorably affects the process of turning steels. And when turning high-temperature steels with T5K10 carbide inserts, the wear of the end fl ank of the cutting edge of the insert is uneven, there are traces of microchipping and a wear groove, which leads to a rapid loss of its cutting ability. Studies have established that the most favorable condition arises when turning high-temperature steels by plasma-ultrasonic machining, both when turning with single-carbide and two-carbide inserts (curves 3, 3ʹ, Fig. 2). Fig. 2. Wear on the back surface of the cutter under various processing conditions when turning steel 20Cr13Ni18 slag
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