OBRABOTKAMETALLOV Vol. 25 No. 3 2023 technology be violated [15, 16], the working conditions of the abrasive tool [17, 18] and the formation of the quality of the treated surface will be changed. In order to minimize deviations of the actual metal removal from the specified (assumed) one, for which the appropriate cutting speed and feed are specified, it is required to obtain empirical dependencies of the entire technological system, which will allow further design of technological processes for grinding rails for various conditions. In view of the foregoing, the main purpose of the research was determination of the optimal modes of rails grinding in the implementation of high-speed grinding technology, providing maximum machining performance with the formation of the specified parameters of the quality of the rail head surface being processed and determination of the main parameters of the technological equipment RSHP 2.0 specific to these modes, such as pressure in the pneumatic system pressing the grinding wheel to the rail and the current load of grinding motors. To achieve this goal, the following tasks were solved: determination of the parameters of the pneumatic system, providing the required forces of pressing the grinding wheel to the rail; determination of the dependence of the current load in the windings of the electric motor on the force of pressing the grinding wheel to the rail; determination of the rated current load of the electric motor to the specified average values of the grinding wheel pressing force against the rail; assessment of metal removal and roughness of the processed surface in various grinding modes. Research methodology Currently, there are a number of test benches [19, 20] on which it is possible to implement research program tests of rail grinding technology. At the same time, it should be noted that all the installations available today are limited to the standard operating modes of existing rail grinding trains and do not allow it to be changed in a sufficiently wide range. In order to fulfill the tasks of studying the technology of rails high-speed grinding, a special rail grinding unit – URSH – was developed and manufactured. The URSH consists of a separate section of track with a length of 100 m, a standard gauge of 1,520 mm (fig. 6a), on which a rail grinding trolley moves (fig. 6b). The trolley is driven by a winch-type drive containing a motor, a transmission (clutch, brake, single-stage gearbox) and a drum with a single-layer winding (fig. 6b). As an energy source, a diesel generator set (hereinafter referred to as a DGS) with a capacity of 200 kW is used (fig. 6d). The operation of the URSH in test mode is automatic, controlled by a control system from a personal computer. Standard rails P50, P65, P75 are used for grinding, which are installed along the axis of the track. In this case, the level of the head of the working rail (test sample) coincides with the level of the rail head of the standard track. The rail is fixed on special brackets, with the possibility of its quick change and the ability to install a working rail with imitation of various defects of the real path. Fig. 7 shows a diagram of the attachment point of the working rail to the standard track. The rail grinding trolley is a non-self-propelled structure on wheels (fig. 8a), for moving along a standard gauge rail track. The trolley consists of a main frame, a frame of transverse displacement, a frame of transverse inclination. A mobile compressor station is located on the main frame to power the pneumatic cylinder pressing the grinding wheel to the working rail. A grinding head control system is implemented on the grinding trolley as on a rail grinding train, in accordance with the patterns in figs. 4–5 (fig. 8b). A transverse tilt frame with a mechanism mounted on it allows for the possibility of tilting the frame of the grinding unit (electric motor with a circle) in the range from +70° to -20° in accordance with the pattern (fig. 1b). The tilt is carried out using a stepper motor and a screw-nut transmission, the accuracy of setting the required angle is ± 0.5°, which is provided by the kinematics of the transmission itself.
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