OBRABOTKAMETALLOV Vol. 24 No. 3 2022 TECHNOLOGY running bogies of the carriages between the wheelsets (Fig. 1, b). Thus, when the carriages were moving, the rolling surface of the rail head was polished. This grinding technology assumed the working movement of the RGC at suffi ciently high speeds – up to 60 km/h and did not require closing tracks for maintenance. At the same time, there were a number of signifi cant drawbacks, such as the rapid salting loading of abrasive bars and the need to break-in it to a specifi c transverse profi le of the rail. In addition, during the grinding process, only longitudinal risks were formed on the processed surface of the rail, which reduced the effi ciency of metal removal. а b Fig. 1. Railgrinder RShV: a – grinding schematic diagram; b – general view of the grinding equipment Due to the above-mentioned drawbacks and the low effi ciency of the process of bar passive grinding, by the mid 90s this was almost completely replaced by the technology of grinding using “active” working bodies – rotating grinding wheels. But, as it was noted earlier, the RGTs implementing the active grinding technology are signifi cantly limited by the maximum speed of the working movement and require tracks to be closed for the maintenance. As a rule, these trains are used for maintenance and reconstruction grinding. Thus, achieving the preventive grinding of rails was complicated by the lack of appropriate equipment capable of grinding rails at high speeds. With the growing density and speed of freight and passenger transportation, and the development of high-speed transportation, the need for preventive grinding without disrupting train movements has only increased. In this regard, in the early 2000s the German company Stahlberg-Rönsch (SRL) proposed a method of high-speed passive grinding of rails with the periphery of the grinding wheel – High Speed Grinding (HSG). This method to some extent eliminated the disadvantages of the known bar passive grinding [13–14] (hereinafter referred to as the HSG method). Using the HSG method, the upper and lateral working surfaces of the rail head are simultaneously ground using cylindrical grinding wheels. These wheels have the ability to freely rotate around its axis and, using the appropriate corresponding mechanism, are pressed against the rail head at a given angle to the direction of movement. The grinding wheels rotate due to the frictional forces between the surfaces of the rail and the wheel that occur during the longitudinal movement of the abrasive tool (Fig. 2, a). Thus, in the course of spontaneous turning of the grinding wheel, continuous renewal of the working surface of the abrasive tool is ensured and, as a result, its salting loading is excluded [14, 15]. In 2007, SRL built a machine that uses the HSG method. The new RC-01 rail grinding train included 96 grinding wheels (Fig. 2, b) and could grind at speeds up to 80 km/h, while removing a layer of metal with a thickness of about 0.05 mm per pass. At that time, the RC-01 was the fi rst and the only rail grinding train in the world that was used to grind rails without the need to stop train movements on the section of rail and without any disruption to freight and passenger trains schedules. The RC-01 operated on the main lines and high-speed lines of Deutsche Bahn Netz AG [14, 15].
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