OBRABOTKAMETALLOV Vol. 25 No. 3 2023 technology The operation of the new train is based on the technology of high-speed grinding of rails, which was developed at the STU in the late 2,000s [8] and underwent preliminary industrial testing [9]. The new technology was proposed based on the theory of cutting during abrasive processing [10–12], wherein an increase in the working speed of a rail-grinding train is impossible without a proportional increase in the speed of rotation of the grinding wheel. Otherwise, an increase in feed can lead to a significant deterioration in the quality parameters of the processed surface and a decrease in metal removal. Increased wear of the abrasive tool is also possible due to a violation of the optimal modes of its operation [13]. Thus, the following conditions were implemented in the high-speed grinding technology: 1) the first condition is that the abrasive wheel is located at an angle α to the surface of the rail being processed with the opening towards the rail grinding train movement direction (“angle of attack”). Due to this arrangement of the grinding wheel, a uniform allowance is achieved between the abrasive grains, while reducing the wear of the abrasive tool (fig. 3). The highest efficiency in the grinding of rails is achieved with the correct selection of angle α, since its value depends on the metal removal. The angle α is taken with provision for the size of the grinding wheel and the average value of the expected metal removal, and is 0.35 degrees in accordance with the calculations according to the equation: 0,3 sin 0.006, ( ) / 2 (250 150) / 2 t D d α= = = - - where t is the expected metal removal, mm (t = 0.3 mm); D is the outer diameter of the grinding wheel, mm (D = 250 mm); d is the inner diameter of the grinding wheel, mm (d = 150 mm). 2) the second condition is to increase the rotation speed of the grinding wheel. An increase in the rotation speed leads to an increase in the metal removal rate, while the cutting force decreases, at the same cutting depth. It has been previously established that increasing the rotation speed of the grinding wheel to 5,000 rpm will increase the working speed of the rail grinding train to 15 km/h without reducing metal removal [9]. The practical application of the adopted technological solutions requires the development of grinding modes, which should form the basis for the design of new working equipment for a rail grinding train. Setting research objectives Currently, the Kaluga Remputmash, together with the Siberian Transport University, is conducting design work on a new rail grinding train. Within the framework of the technical project, the corresponding characteristics of all control systems for the rail grinding process are laid down, which depend on the implemented operating modes of the rail grinding train. The operation of rail grinding trains is characterized by fundamental differences from grinding on machines in stationary conditions [14]. Grinding of rails is carried out due to the force closure of the kinematic pair “abrasive wheel – surface being processed” (fig. 4). Each individual grinding wheel is pressed against the rail head by a pneumatic cylinder through a drive motor mounted on a motor plate. The axes of rotation of the parallelogram suspension are fixed on the end plate of the block of the grinding trolley. This design ensures a constant perpendicularity to the axis of rotation of the circle relative to the longitudinal axis of the rail. Fig. 3. Schematic representation of interaction of an abrasive tool with a rail during high-speed grinding
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