RU110378U1 - SLEEPER - Google Patents

Abstract

 A sleeper containing an upper and lower bed, covered on top with a metal strip rigidly fixed on it with two linings fixed at the points of support of the rails, and fasteners for connecting these elements to each other, characterized in that the sleeper is facing upwards and the metal strip is divided into two identical parts, each of which has a width of at least the width of the sleepers, and their length L and thickness H are determined from the following relations:! ! ! where Pmax is the maximum vertical force transmitted to the sleeper from the rolling stock, n; ! b is the width of the sleepers, mm; ! [σd] - permissible compression stress of the sleepers, MPa; ! Mmax is the maximum bending moment that occurs in a dangerous section during joint bending of the lining together with the strip, N mm; ! bn is the width of the metal strip, mm; ! [σC] - allowable tensile stresses during steel bending, MPa; ! h is the thickness of the lining in a dangerous section, mm

Description

The utility model relates to the field of railway construction, namely, to the construction of rail track foundations of technological tracks laid in areas of industrial enterprises that handle rolling stock with increased train loads.

A known design of sleepers (RU No. 102621, ЕВВ 3/42, 03/10/2011), containing the upper and lower beds, made of reinforced concrete, but equipped with damping elements made of wood installed in the places of support of the rails on it to mitigate the dynamic loads transmitted from the wheels of the rolling stock to the base. A decrease in the level of dynamic interaction between the crew’s wheels and the rail-sleeper grid reduces the wear rate of metal elements of the track and rolling stock, which is especially important for tracks on reinforced concrete sleepers, where, due to the rigidity of the rail base, this level of dynamic interaction is especially high.

Lack of design makes itself felt on the factory tracks, on which crews turn with axle loads 2-2.5 times higher than the loads of public roads. Under these loads, residual deformations of the rail linings occur. Curved linings cut into wood. Its short pieces are not just frayed. They split and crumble, losing their damping properties in the very first days of operation.

The disadvantage of the design, limiting the scope of its application, is the extremely low wear resistance of the damping elements due to their relatively small geometric dimensions.

Closest to the proposed technical solution is the design of the sleepers (RU No. 2340716, ЕВВ 3/02, December 10, 2008), containing the upper and lower beds, covered on top by a metal strip with two linings fixed to it fixed on the rail supports , and fasteners for connecting these elements together. The sleeper made of solid timber allows more fully use the strength and durability characteristics of wood than short wooden fragments inserted into the recesses of the concrete sleepers of the analog structure. A metal strip distributes the load from the rails to almost the entire length of the sleepers. This minimizes the compressive stresses in the sleepers and the rate of wear of the wood. In addition, the strip together with the linings reliably resists bending. The absence of permanent deformations of the strip and lining also contributes to the preservation of wood.

However, the very presence of metal strips is the cause of negative factors that reduce the efficiency of the sleepers and its technical and economic indicators in comparison with traditional wooden sleepers. These factors are as follows:

1. During operation under the metal strip, the wear of the wood occurs with the formation of a recess in the sleeper, corresponding to the size and shape of the strip itself in plan. During precipitation, this depression is filled with water, which is absorbed into the walls and bottom of the depression. Increasing the moisture content of wood leads to a decrease in its characteristics of strength and wear resistance. A similar process occurs in sleepers that are not covered by a strip. Only there, indentations form within small areas - under the lining. And in our case, the strip extends to almost the entire length of the sleepers. Moistening of wood occurs not only at the ends, but also in its middle part, where a decrease in the strength properties for a sleeper working in bending under increased loads is especially dangerous for its bearing capacity.

2. The sleeper, in which the rail threads are not isolated from each other, cannot be used on tracks intended for inclusion in the system of electric centralization and self-locking. In the structure under consideration, a metal strip violates this insulation, which excludes the possibility of its use in the field of automatic control of transportation processes. This contradicts modern trends in vehicle automation.

3. Elementary calculations show that even under increased loads, the metal strip has excessive safety margins, which, with a rational distribution of the material of the structure, will allow one to obtain savings by reducing its metal consumption.

Thus, the design drawback is that one of its elements, the metal strip, does not fully meet its functional purpose of increasing the service life of wooden sleepers, excludes the possibility of using the design in automated transport control systems and reduces the overall design efficiency .

When developing a utility model, the problem was solved of creating a design of wooden sleepers of increased wear resistance and cost-effectiveness in manufacturing, suitable for laying on the way, designed to be included in electrical centralization and auto-lock systems.

The technical result is achieved by the fact that the sleeper containing the upper and lower beds, covered from above by a metal strip rigidly fixed on it with two linings fixed at the points of support of the rails, and fasteners for connecting these elements together, the sleeper is turned upside down, and the metal the strip is divided into two identical parts, each of which has a width of at least the width of the sleepers, and the length L and thickness H are determined from the following relationships:

where P _max is the maximum vertical force transmitted to the railway sleepers from rolling stock, n;

b is the width of the sleepers, mm;

[σ _D ] - permissible compression stress of the sleepers, MPa;

M _max - maximum bending moment that occurs in a dangerous section during joint bending of the lining together with the strip, n mm;

b _n is the width of the metal strip, mm;

[σ _C ] - allowable tensile stresses when bending steel, MPa;

h is the thickness of the lining in a dangerous section, mm

The essence of the proposed technical solution is explained using the drawings:

figure 1. General view of the wooden sleepers of the proposed design.

figure 2. Its cross section is AA.

Sleepers 1 contains the upper 2 and lower 3 beds. Its widest face, which is its lower bed 3, is facing upwards to enable any part of the strip 4 resting on it to interact with it as much as possible of the contact area 5. Unlike the prototype, in this design, strip 4 does not extend to the entire length of the sleepers 1, but is divided into two sections 6 and 7. The width b _{n of} each of them is not less than the width b of the sleepers 1. Experience shows that when the rail 8 rests on the sleepers 1 only through the lining 9, the width of which b _{0 is} less than the width b of the sleepers 1, then the wear of the wood occurs with the formation of a recess 10 having a width b _u equal to the width b _{0 of the} lining 9. It is shown in dotted lines in FIG. The walls 11 constantly hold inside this recess 10 water that accumulates during rains. Water gradually impregnates the wood, reducing its characteristics of strength and wear resistance in the under-rail zone, where sleepers 1 experience the greatest compressive stresses and undergo the most intense mechanical wear. This process is well studied on public roads, but there it occurs in short sections within the rails 9, and in the prototype design, the recess 10 extends over almost the entire length of the railroad tie, including its middle part 12 between the rails 8 and reduces the bearing capacity of the railroad tie 1 when bending work. In the proposed design, the metal strip 4 is divided into two identical parts 6 and 7, the width b _p , each of which is not less than the width b of the sleepers 1, so that the wear of the wood does not lead to the formation of a recess 10. The remaining sizes of parts 6 and 7 are made optimal from the point of view strength and metal consumption. The length L of each of them along the sleepers 1 is determined from the condition of compressive strength of wood:

Where - maximum compressive stress in the rail track area of the sleepers, MPa;

- permissible compression stress of the sleepers, MPa.

where P _max - the maximum vertical force transmitted to the sleepers 1 from the rolling stock, n;

L is the length of each part 6 and 7 of the strip 4, mm;

b is the width of the sleepers 1, mm;

In accordance with (1):

where from

The thickness of the metal strip 4 is determined from the condition of its bending strength:

Where - the maximum tensile stress of the strip 4 in bending, MPa;

[σ _C ] - allowable tensile stresses during steel bending, MPa.

where M _max - the maximum bending moment that occurs in a dangerous section BB in the joint bending of the lining 9 together with the strip 4, n mm;

W is the moment of resistance to bending of the lining 9 together with the strip 4, mm ³ ;

where b _n is the width of the metal strip 4, mm;

H is the thickness of the metal strip, mm;

h is the thickness of the lining 9 in a dangerous section BB, mm.

At the lining 9 with a bend, the thinnest section BB is located inside the track at the edge of the supporting platform 12 under the rail 8. This is a dangerous section BB.

In accordance with (5):

After substituting (7) in (8), we obtain:

where from

When choosing a steel strip 4 from the assortment, its width b and thickness H can be taken as the closest to the calculated one without subsequent adjustment to the nominal dimensions. This will allow you to do without additional labor costs for machining the strip.

The device operates as follows:

During the operation of wooden sleepers 1 of the proposed design on their surfaces will not be formed recesses 10 that hold water. On the contrary, when passing through the sleeper 1 of each wheelset (not shown in Fig.), Excess moisture contained in the annual layers of wood will be squeezed out on both sides from under the metal strip. This will prevent the saturation of wood with moisture and will help preserve its physical and mechanical characteristics of strength and wear resistance. Changing the conditions for the interaction of the sleepers 1 with the metal strip 4 and the optimization of the ratios of strength and metal intensity of the latter will increase the economy of the structure, and the separation of the metal strip 4 into two independent parts 6 and 7 ensures mutual isolation of the rails 8 from each other and will enable the use of sleepers 1 of the proposed design on ways intended for entry into the systems of electric centralization and self-locking.

Claims (1)

A sleeper containing an upper and lower bed, covered on top with a metal strip rigidly fixed on it with two linings fixed at the points of support of the rails, and fasteners for connecting these elements to each other, characterized in that the sleeper is facing upwards and the metal strip is divided into two identical parts, each of which has a width of at least the width of the sleepers, and their length L and thickness H are determined from the following relationships:

where P _max is the maximum vertical force transmitted to the railway sleepers from rolling stock, n; b is the width of the sleepers, mm; [σ _d ] - permissible compression stress of the sleepers, MPa; M _max - the maximum bending moment that occurs in a dangerous section during joint bending of the lining together with the strip, N mm; b _n is the width of the metal strip, mm; [σ _C ] - allowable tensile stresses when bending steel, MPa; h is the thickness of the lining in a dangerous section, mm