OBRABOTKAMETALLOV technology Vol. 26 No. 3 2024 The research of the new high-speed electric drive for the realization of high-speed rail grinding technology was carried out in the following sequence: 1. The air pressure of 0.5 atm was set in the pneumatic system for pressing the grinding wheel to the rail. 2. At the specified pressure, three grinding passes were made in each of the following grinding modes: – speed 15 km/h at a grinding wheel rotation speed of 5,000 rpm; – speed 20 km/h at a grinding wheel rotation speed of 6,000 rpm; – speed 30 km/h at a grinding wheel rotation speed of 7,000 rpm. 3. During the grinding process, the current load readings on the stator windings of the grinding wheel were recorded. 4. After each pass, the transverse profile of the rails was measured with the evaluation of metal removed from the rail and determination of the average value of removed metal based on the results of three passes. 5. After changing the air pressure in the pneumatic system of pressing the grinding wheel to the rail, points 2–4 were repeated. The following pressure values in the pneumatic system were set during the tests: 0.5; 0.8; 1.0; 1.2; 1.5; 1.8; 2.0; 2.5; 2.8; 3 and 3.5 atm. Results and its discussion The summarized results of the study of high-speed electric drive operation modes are shown in Table 2. Based on the measurement results (Table 2), the dependences of changes in the average values of metal removed from the rail head depending on the current load in the stator windings of the high-speed electric motor are established, which are presented in Figure 5. The graphs (Fig. 5) show that there is a tendency for metal removal to increase with increasing current load in the electric motor windings to certain values, after which the metal removal values begins to decrease. This pattern is characteristic for all investigated modes of grinding. It can be assumed that such dependence characterizes the efficiency of abrasive tool operation with the established grinding modes. So, the minimum current load is characterized by an insignificant pressure force of the grinding wheel to the rail. This leads to insufficient embedding of abrasive grains into the machined surface with the formation of chips of minimum cross-section and gradual blunting of abrasive grains at minimum cutting forces. Ta b l e 2 Results of a study of the operating modes of a high-speed electric drive Pressure in the pneumatic cylinder (pressing force), atm Grinding modes 15 km/h (5,000 rpm) 20 km/h (6,000 rpm) 30 km/h (7,000 rpm) Current load, А Average value of removed metal, mm Current load, А Average value of removed metal, mm Current load, А Average value of removed metal, mm 0.5 72 0.15 78 0.11 74 0.10 0.8 86 0.21 81 0.12 82 0.11 1.0 94 0.26 91 0.21 86 0.15 1.2 102 0.33 95 0.22 96 0.21 1.5 105 0.35 101 0.30 99 0.24 1.8 115 0.20 103 0.32 104 0.17 2.0 119 0.19 110 0.20 106 0.14 2.5 123 0.19 115 0.18 110 0.12 2.8 131 0.12 125 0.14 115 0.10 3.0 140 0.10 130 0.10 125 0.05 3.5 140 0.10 140 0.05 130 0.03
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