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17Scientific Journal Impact Factor
EXTEND THE SERVICE LIFE OF THE RAILS WITH THE HELP OF
GRINDING
Abstract: This article discusses the lengthening of the service life of rails. Technologies of rail grinding in the conditions of the railway track, which allowed to form technical and technological solutions, the introduction of which makes a significant contribution to the development of the railway industry and the economy of the country as a whole by increasing the efficiency of operation. Rail defects of their appearance on the head, measuring the wear of the rail head and ego elimination.
Key words. Rails, grinding wheels, indicator, rail-grinding train.
Аннотация: В статье рассматривается вопрос увеличения срока службы рельсов. Технологии шлифования рельсов в условиях железнодорожного пути, позволившие сформировать технические и технологические решения, внедрение которых вносит значительный вклад в развитие железнодорожной отрасли и экономики страны в целом за счет повышения эффективности операция. Дефекты рельса, их появление на головке, измерение износа головки рельса и устранение эго.
Ключевые слова. Рельсы, круги шлифовальные, индикатор, рельсошлифовальный поезд.
The most expensive element of the construction of the upper structure of the railway track is the rails, which are purchased at the cost of foreign currency. In this regard, the maximum extension of the service life of rails from the moment of their laying to replacement is relevant. One of the most effective methods of extending the service life of rails is rail grinding.
In the system of track management, rail grinding is currently becoming one of the priority areas. Rail grinding is a necessary part of the economical maintenance of the upper structure of the track. Preventive grinding allows you to prevent the appearance of defects on the rolling surface, prevent (or significantly delay) the development of contact fatigue defects in the rails. The list of rail defects eliminated and reduced by grinding includes the following types: undulating wear, saddles,
Abdualiyev Elyorbek Begaliyevich, Mirzaxidova Ozoda Mirabdullayevna,
Khamidov Maqsud Kamalovich. Tashkent State Transport University
INTRODUCTION
MATERIAL AND METHODS
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corking, mechanical damage, flattening, crumpling, plastic deformations of the head, peeling and chipping of metal on the working edge of the head, knocked down ends of rails in joints, irregularities in welded joints, defects due to violations of manufacturing technology[1].
As a result of the removal of surface defects, vertical dynamic forces, noise and vibrations are reduced, the service life of rails, rail fasteners and sleepers is increased, and the track alignment cycle is significantly lengthened in plan and profile. In addition, the cost of maintenance and repair of rolling stock is reduced and its service life is increased due to the reduction of wear and fatigue of parts and components.
Grinding is required to be carried out with the help of special technical means, and the volume of the removed material and the resulting transverse profile must be regulated by special documentation.
There are three types of rail grinding:
* preventive, providing for regular removal of the most damaged metal layer at the stage of slow growth of irregularities and surface cracks, which allows to prevent their accelerated development;
* profile grinding, in which the rail head is ground along the entire perimeter in order to eliminate significant surface defects and recreate the desired profile;
* grinding, designed to eliminate undulating wear and short irregularities of other types on the rolling surface of the rails.
The service life of the rails is a function of their operation under the rolling stock, the type and capacity of the rails, the characteristics of the upper structure and rolling stock, the operating conditions of the track and the manufacturing technology of the rails. Rails fail due to wear and defects. They should be removed from the track when worn to a certain permissible value; this factor determines the service life of the rails. Since the rail head is worn by the wheels passing through it, the wear is measured by the wear area ® of the cross-section of the rail head (Fig. 1).
s £
CO
Fig. 1 of the cross-section of the rail head. ®=ßT<[®] . ®=hpr*bg-s . Here ß is the specific wear of the rail head, mm2 /mmt gross; T-past gross tonnage;
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[®]-permissible wear area, mm2; hpr - width of the rail head; bg-normalized limit wear of the rail head;
e-takes into account the difference in the shape of the head and the imaginary rectangle, which is assumed to be 70 mm2.
On the curved sections, ® depends on the depth hpr of the reduced wear -vertical and lateral (vertical wear h vertical is measured along the axis of the rail head, lateral h lateral horizontally at a distance of 13 mm from the rolling surface of the head).
hpr hver +n* hhor
Transverse fatigue cracks in the head in the form of a light or dark spot, which arose from an internal or external longitudinal crack formed due to insufficient contact fatigue strength of the metal, and led to the failure of the rail after passing the warranty tonnage (Fig. 2).
Fig. 2 Schematic representation of the rail defect [2].
Important measures to extend the service life of rails in transit are the grinding of their heads with rail-grinding trains to remove unevenness and surface damaged metal layer from the rolling surface. Based on many years of experience, German railway workers claim that grinding rails can significantly extend the service life of metal elements of the railway track. In addition, the search is still ongoing for the grade of rail steel that will require the least frequent grinding, which will reduce the running costs of both workers and the life cycle of the rails.
Employees of DB (the national railway company of Germany) are constantly trying to extend the" life " of German rails. The new high-speed trains put a serious strain on the places where the rails and wheels of the train come into contact. Another problem is the small number of technological interruptions in the movement of trains, which limits the time of work. Therefore, railway workers are engaged in research that will be able to stop or slow down the appearance of defects on the rails. Experience suggests that most of the damage occurs not because of the actual contact of the wheel and rails, but due to the rocking of the train to the left and right in the
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course of movement. As a result, there are dents and grids of cracks. Scientists aim to increase the operational life of rails (Fig. 3).
ft, pcs/km
Q 2 GO 400 800 O I OO 200 3QO 400 500 60Q 700
7", mln .tonna.T^m-tto mln.totina ."b>;ni1rt:c>
Fig. 3 Scientists aim to increase the operational life of rails.
a — on straight lines and curves (for medium conditions-link track, unpolished rails); b — polished rails of group I: 1, 2, 3-on the 2nd main track, respectively, in the middle of the whip, general withdrawal, on equalizing spans; 4, 5, 6 — the same on the 1st main track.
A special feature of the Vossloh rail grinding train is the high-speed grinding (HSG) method, which allows you to maintain the quality for a long time at low costs.
The grinding process is economical and accurate: purposeful removal of the hardened layer from the rail surface prevents the appearance of transverse cracks of the rail head and corrugation. The smooth adjustment of the grinding unit parameters allows you to optimize the cross-section of the rail-at an operating speed of up to 80 km/h. Exhaust devices capture the removed material, dust containers can hold up to 6 tons. Thanks to the modular design of the HSG-2 (Fig. 1), the coupling of two grinding trains is possible. As a result, the performance or range of the train is doubled, which saves time and costs.
The length of the HSG-2 is 45 m, the axle load is 20 t, grinding is carried out by four units, which are equipped with 96 grinding stones.
The performance of the HSG-2 train per shift is up to 100 km.
Material removal: 0.1-0.3 mm.
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Fig. 4 HSG-2 grinding train. [3].
Technologies of rail grinding in the conditions of the railway track, which allowed to form technical and technological solutions, the introduction of which makes a significant contribution to the development of the railway industry and the economy of the country as a whole by increasing the efficiency of operation, maintenance and repair of the railway track by ensuring the quality of rail profiling[4,5].
Fig. 5 Rail grinding. a) before grinding the rails, b) after grinding the rails[6,7].
CONCLUSION
If the average service life of the rails is 20 years, then as a result of grinding, it will be extended to 28 years. The cost of purchasing new rails will be deferred for 8 years. Thus, profile grinding of rails using special equipment requires accelerated implementation at JSC "Uzbekistan Railways" from a technical and economic point of view.
REFERENCES
1) G. M. Shakhunyants /Iron road/ Moscow "Transport" 1987
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2)Instruction rail defects. Classification, catalog and parameters of defective and strodefect rails 10.02.2015 g No. 17.
3) www.howlingpixel.com Highspeed Grinding HSG-RC-01 Germany 2018
4)https://cyberleninka.ru/article/n/elimination-of-impulse-irregularities-on-the-rail-head-with-the-help-of-grinding
5)https://uziournals.edu.uz/cgi/viewcontent.cgi?article=1059&context=tashiit
6) https://uzjournals.edu.uz/cgi/viewcontent.cgi?article=1036&context=tashiit
7)https://cyberleninka.ru/article/n/condition-of-culverts-on-the-high-speed-section-of-the-tashkent-syrdarya-railway-line
