OBRABOTKAMETALLOV technology Vol. 26 No. 3 2024 Introduction Grinding of railway rails is one of the operations for the current maintenance of the track top structure, which forms the rail profile and removes defects that occur during operation. Special rail grinding trains are used for rail grinding. These trains are equipped with abrasive wheels, which process the surface of the rail head according to the flat grinding scheme [1–4]. For the work of rail grinding trains on the railway system, special “technological windows” are organised, when running lines are closed for the movement of any types of rolling stock, which leads to financial losses for transport companies. The organisation of such “windows” is caused by the fact that the speed of a rail grinding train is very low and reaches 4–8 km/h at the grinding wheel rotation speed of 3,600 rpm [5–7]. Therefore, the task of reducing the operating time of a rail grinding train by increasing the operating speed is a priority for the development of the railway industry. To solve this problem, the RSHP 2.0 project is being implemented by the Siberian Transport University and Kaluga Remputmash (KRPMS). Within the framework of this project the rail grinding train RSHP 2.0 is being developed. Its operating speed will be increased up to 15 km/h, while the metal removal rate will remain unchanged at 0.2 mm. In accordance with the previously conducted studies on high-speed rail grinding [8–10] and the theory of cutting [11–13], an increase in the operating speed of the rail grinding train can be achieved by increasing the grinding wheel speed [14]. Preliminary industrial and laboratory tests [15, 16] have shown the possibility of increasing the working speed of the RGP 2.0 up to 15 km/h at the grinding wheel rotation speed of 5,000 rpm, and in the future up to 20–30 km/h at 6,000–7,000 rpm. At the same time, the amount of metal removed from the rail remains unchanged and averages 0.2 mm. Fundamentally, the working equipment of the RSHP 2.0 does not differ from the used rail grinding trains and is characterised by force closure of the kinematic chain “abrasive wheel - machined surface” [17]. Due to the pneumatic cylinder, grinding wheels are pressed against the surface of the rail head. The pneumatic cylinder acts on the electric motor, which is installed in the lever mechanism of the working equipment (Fig. 1). The pressure in the pneumatic cylinder is regulated depending on the load on the electric motor, which is characterised by the current in the stator. The scheme of controlling the grinding wheel pressure force is shown in Figure 2. During rail grinding, a certain metal removal should be achieved to obtain the required rail profile. However, grinding with a certain metal removal rate is not possible due to the elastic suspension of the grinding head. In addition, deviations of metal removal from the expected values will lead to violations of the accuracy of the formation of the rail transverse profile [18,19], as well as to changes in the operating conditions of the abrasive tool [20] and deterioration of the quality parameters of the machined surface. Reducing the difference between the specified metal removal during grinding and obtained can be achieved by establishing empirical dependencies of technological parameters of grinding modes. The main element that determines the modes of grinding is the drive of the grinding wheel, i.e. the electric motor. The characteristics of the electric motor determine the settings of the grinding wheel pressure control system (Fig. 2). The crucial task in the development of the RGP 2.0 is the availability of an industrial model of a highspeed electric drive of the grinding wheel with increased shaft speed. During preliminary studies of modes of high-speed rail grinding [15, 16], the required technical characteristics of the high-speed electric drive were determined to ensure the required productivity of the rail grinding train, which are presented in Table 1. In Fig. 1. Grinding head mounting pattern: 1 – abrasive wheel; 2 – electric motor; 3 – motor-mounting plate; 4 – parallelogram suspension; 5 – pneumatic cylinder; 6 – block plate; 7 – axis
RkJQdWJsaXNoZXIy MTk0ODM1