EP0698147B1 - Resilient rail fastening device - Google Patents

Abstract

A resilient rail fastening device (4) has an elastic intermediate layer (8) arranged between a rail foot (2) and a hard support, for example a sleeper (6), provided with a profile. The compression surface (17, 18) which faces the support (6) has substantially closed marginal strips (10-13) which in turn enclose a depressed surface (17, 18) from which project individual small-surface compression point (11). Such a geometric design of the elastic intermediate layer (8) allows a certain elastic rigidity of the intermediate layer (8) to be adjusted by modifying the compression surfaces (17, 18). A thermoplastic elastomer of non-crosslinked rubber or an ethylene-vinyl acetate copolymer are preferably used for the intermediate layers (8). Such intermediate layers are particularly suitable for highly stressed railways with a W-shaped superstructure. A special injection molding tool with exchangeable plates for shaping compression surfaces of different sizes is also disclosed.

Description

The invention relates to a resilient rail fastening with an elastic intermediate layer.

Modern rail fastenings on sleepers of a railway track are usually equipped with intermediate layers between the rail foot and the sleeper to ensure an elastic train run. It does not matter whether concrete sleepers, e.g. the usual size B 70 or wooden or steel sleepers, as a trough sleeper or Y sleeper with two supports per sleeper for each rail.

As a rule, the rails are also elastically tensioned by spring elements that act on the rail foot and in turn are anchored to the support, the sleepers or a bridge substructure or other solid substrates by screws or eyelets. Such a resilient fastening arrangement for rails on sleepers with an elastic intermediate layer is disclosed in DE-A 32 43 895 for a track in ballast bedding.

Such elastic intermediate layers are also known for height-adjustable rail fastenings, in particular to be used in a ballastless superstructure (DE-A 26 00416), which at the same time can have an electrical insulating effect, provided that the bracing on the support itself is insulated from the rail. Otherwise, the bracing must be provided with insulation separately. Lateral rail guidance is usually ensured by angle guide plates, which in turn can be made of plastic or steel.

Instead of such angle guide plates and a screw connection that presses on a spring element holding the rail foot, the spring element itself can also be mounted in a special support, e.g. a ribbed plate, be locked and hold the rail foot on the ribbed plate. In such a rail fastening intended for ballastless superstructure according to CH 396 960, a rubber plate was chosen as the elastic rail underlay, which is equipped with continuous groove profiling in the longitudinal direction of the rail both on the rail foot side and on the support side. This obviously gives the intermediate rubber plate increased elasticity, although this is not disclosed in the CH patent.

From DE-AS 1 014 139, in addition to a two-sided, an intermediate layer made of rubber, which is provided on one side with a network of compression surfaces with integrated compression points, and which protrude as cylindrical or angular columns from a recess surface is known. This intermediate layer is to be manufactured as an endless belt, possibly with a border, and cut on site. A specific application or other material parameters are not disclosed.

From DD-PS 64 820 and DE-A 23 47 991 intermediate layers made of rubber or poplar wood or rubber or unspecified plastic are known, which are provided on the side facing the threshold with grooves for changing the spring stiffness.
The design principle is that the intermediate layer is more flexible / less stiff in the longitudinal direction of the rail than in the transverse direction. The edge pressure on the threshold is to be reduced in this way so as not to destroy the intermediate layer. Both publications therefore focus on a problem specific to rubber or poplar wood.

A large number of further rail supports are known from practice, which consist of polyethylene or polyurethane, i.e. thermoplastic plastics, the compression surfaces, i.e. the surfaces of the intermediate layer, which face the support or the rail foot, can be smooth or can also be provided with a profiling from the rail foot side.

It has been found that such elastic intermediate layers must be constructed from the materials mentioned for the respective special application or their material composition must be specially modified in order to meet the demand for smooth running of the train, low noise emissions into the environment and as constant as possible spring properties at high and low To ensure outside temperatures. In practice, however, this has never been achieved optimally, and especially in the case of high-speed railway lines, it turns out that the elasticity of the track is inadequate and has a negative effect on the service life of both the roadway and the vehicles. A particular disadvantage of the intermediate layer according to the prior art is extreme hardening at temperatures of −20 ° C. and lower, which is intensified by the accumulation of dirt between the lower surface of the rail foot and the intermediate layer, especially if the intermediate layer does not have a smooth surface. Due to the elastic rail fastenings to be used today and the unavoidable tilting of the sleepers during the rollover and the prevailing air suction, fine dust and water can accumulate on the surface of the intermediate layers. In winter in particular, freezing water and stiffening pollution can then cause a significant change in the spring characteristics both in the static and dynamic load condition. The initially conceived resilient property of the rail fastening is thereby negatively changed to an unpredictable extent.

In addition, it is known from the prior art that when the cross sleepers are tilted, in particular rubber intermediate layers, but also conventional plastic intermediate layers made of polyurethane or polyethylene, are squeezed in such a way that the intermediate layer is destroyed. The same can be seen for the threshold-side edge areas of the intermediate layers, if corresponding transverse forces cause the rail foot to tip and load the intermediate layer beyond the designed surface pressure.
Although polyurethane is suitable in principle as a material, it is either not resistant to hydrolysis or, if modified accordingly, is expensive. Vulcanized rubber liners can be totally destroyed, in particular crushed, by tearing the molecular crosslinking.

Therefore, the invention is based on the problem of proposing a resilient rail fastening with an elastic intermediate layer, in which the environmental and load-related, destructive conditions can be largely compensated, the type of elastic intermediate layer should be adaptable to the special applications and inexpensive to manufacture.

The problem is solved according to the invention by the features specified in claim 1. Further features of the invention are covered in the subclaims.

Such intermediate layers can be used in the conventional K superstructure with a spring washer; However, their full effect can only be achieved with modern resilient rail fastenings, e.g. the so-called W superstructure, with a w-shaped steel spring, which is fixed by a screw to the support, the sleepers, and thus tensions the rail foot.

The new intermediate layer prevents contamination of the rail support or the penetration of water into the gap between the rails and the threshold or the solid surface characterized in that the intermediate support is provided with a smooth surface on the rail foot side and the setting of the spring index variable for the various application surfaces by a corresponding variation of the compression surfaces facing the support, the threshold. The corresponding surface of the intermediate layer is provided with a continuous, closed edge strip which encloses a depression surface from which further portions of the compression surface rise in the form of small-area compression points and serve as a support surface. This - with the threshold formed - closed space is kept essentially tight by the usual compression of the skirting due to rail deflection or rail foot tilt when appropriate vertical and lateral forces occur, so that the depression is not affected by air suction or similar environmental conditions with water or fill dirt.

In the alternative, the edge strip is interrupted transversely to the longitudinal direction of the rail by drainage channels which are connected to the recessed surfaces. When the fastening points are rolled over, the elastic intermediate layer is compressed and air or, exceptionally, water or other foreign bodies are displaced from the area of the bearing surface.

The spring stiffness of the intermediate documents, ie their spring number adapted to the specific conditions, can be adjusted for each individual case by the choice of size and the number of small-area compression points in combination with a possibly variable width of the edge strip. The type of sub-swelling, e.g. ballast bed or solid carriageway, as well as the load spectrum, e.g. a high-speed route or route with high tonnage loads (cumulative rolling load), small or large curve radii and the like should be considered as an individual case.

It is initially assumed that the sum of the load-bearing compression points within the depression area is less than half of the area portion of the depression area, so that there is a sufficiently large space in which possibly accumulating dirt can remain for so long without supporting the compression areas surrounding it .

The proportions of the stiffness behavior and the overall stiffness attributable to the compression points can be varied in addition to the above-mentioned parameters size and number by further properties. This includes the size distribution of points of different sizes over the depression surface, the surface shape, for example angular or round, the effective recess depth and the material.
For reasons of manufacturing technology, each compression point is designed as a truncated cone or truncated pyramid, ie its top surface effective at the start of loading is smaller than its base surface coinciding with the recess surface. This area difference, which changes continuously with the recess depth, or the corresponding slope steepness of the compression points can be included in the calculation of the spring stiffness. In particular, the ratio between the minimum and maximum loading of the intermediate layer and their desired effects on the spring stiffness of the entire rail fastening can be set in this way. The spring stiffness also includes the material used for the intermediate layer and its behavior at the occurring temperatures from - 30 ° C to + 80 ° C.

In the invention, thermoplastic elastomers from the group of uncrosslinked rubbers (TPE) and ethylene-vinyl acetate copolymers (PE copolymers) are used. Carbon black is added for UV stabilization.
The statistical load is usually taken into account when setting the spring stiffness, e.g. at 50 kN - secant stiffness between the load levels 18 - 68 kN - as well as at room temperature, and the dynamic behavior, for example as a result of the rollover frequency caused by the railway operation. Ideally, the spring stiffness should be constant under variable conditions; however, this cannot be realized. For these reasons, an adaptation to the most frequent traffic loads is made.

The invention solves a particular problem to which the prior art has hitherto not given sufficient attention. Calculations of the executives attacking the rail head and vertical load forces have been known for a long time, the results of which act as surface pressure on parts of the rail support. The vertical loading forces result from the weight of the rolling vehicles, while the executives attacking the rail head horizontally to a lesser extent from the sinusoidal movement of the vehicles on the track and the consequent striking of the wheel flanges on the rail head, to a greater extent by centrifugal forces corresponding to an arc radius of the track , the weight of the heaviest vehicle and any existing rail superelevation. The forces on a rail support can easily reach the value of 6 MP. Depending on the load, e.g. slow-moving or stationary train or fast-moving train of high weight in a tight curve, this results in a surface pressure of the rail foot, with the rail fastening means prestressing the rail, from 0 to approximately 1 kN / cm ² . When the train is stationary, up to 400 N / cm ² can occur on the rail foot towards the middle of the track, for example with the S 54 rail, but only 10% of this load can occur on the opposite side of the rail foot, due to the usual inclination given to the rail towards the middle of the rail of, for example, 1:40. The continuous edge strips on the rail foot edges take this load into account because there is a larger load-bearing area portion of the elastic intermediate layer. A similar compression pattern for the elastic intermediate layer results in the longitudinal direction of the rail due to the rail deflection and the play in the elastic rail foot bracing. Here too, the edge strips of homogeneous thickness provide appropriate support for the rail foot.

The intermediate layers according to the invention have shown in practice that, with the dynamic load present, they show only slight changes in the characteristics of their elasticity which lie within the permissible tolerances for such rail bearings, and thus prevent the elastic intermediate layer from being destroyed in the specific applications. The closed edge strips also prevent the rail from sloping with larger lateral guiding forces, because the locally greater spring stiffness brings about a corresponding reaction force.

The underside of the intermediate layer is provided at the edges lying in the longitudinal direction of the rail with a wrap-around strip or rib, which provides a positive locking of the intermediate layer on the threshold. This wrap-around strip preferably does not extend over the entire width of the intermediate layer, but is limited to a length of 10-60% of the width of the intermediate layer.
In a preferred embodiment, the wrap-around bar is recessed in the central area and is only pronounced at corners of the intermediate layer over a length of approximately 20% of the total width. There are several technical reasons for this. In this way, a concentrated accumulation of material with corresponding flow problems during production is avoided. In addition, when the intermediate layer is installed, its seat can be checked more easily from the threshold side, since the rail seat or the threshold support is not covered in the central region.

In a special embodiment for concrete sleepers or other sleepers which are provided with angle guide pieces for fastening the rails, the elastic intermediate layers in the rail transverse direction have a protruding rib on which the angle guide pieces can be placed. In order to the elastic intermediate layer is fixed in its target position at the same time as the rail foot is braced.

In practical tests, it has been found that with ballast bedding for load frequencies> 50 Hz to over 100 Hz, in particular for the rapid transit of the railways, a static spring rate of approximately 50 kN / mm or higher to approximately 90 kN / mm at room temperature is favorable. On a solid carriageway, a static spring rate of <30 kN / mm is preferred at Deutsche Bahn, calculated for an area of 148 x 165 mm reference size of the intermediate layer, with the larger recess depths of the intermediate layer required for elastic train travel.
These values can be easily achieved with TPE material at recess depths of 0.5 - 1 mm (ballast bedding) and about 2 mm (solid roadway). For higher spring stiffness and recess depths of up to 0.5 mm, PE copolymers are preferred, which in the long run deliver twice as high values. In contrast, the intermediate layers used according to the prior art were, as a rule, many times more rigid.

The different design of the surface support elements, in particular the compression points within the recess surface, can expediently be achieved by arranging an exchangeable tool plate within the injection molding tool. Such plates can be kept in stock for a different number of compression points and / or different sizes and shapes such as round or angular or truncated pyramid or truncated cone-shaped compression points with different slope, also for different or the same total surfaces. This makes it possible to produce intermediate layers of different overall spring stiffness with one and the same tool.

Fig. 1

eine federnde Schienenbefestigung des W-Oberbaues mit elastischer Zwischenlage im Teilschnitt;

Fig. 2

eine Draufsicht gemäß Ansicht A in Fig. 1 auf die elastische Zwischenlage;

Fig. 3

einen Schnitt B - B gemäß Fig. 2 durch eine elastische Zwischenlage;

Fig. 4

eine zweite Ausführungsform einer Zwischenlage gemäß Ansicht A in Fig. 1.

The invention will be explained in more detail with the aid of schematic drawings. Show it

Fig. 1

a resilient rail fastening of the W superstructure with elastic intermediate layer in partial section;

Fig. 2

a plan view according to view A in Figure 1 of the elastic intermediate layer.

Fig. 3

a section BB according to Figure 2 by an elastic intermediate layer.

Fig. 4

a second embodiment of an intermediate layer according to view A in Fig. 1st

On a concrete sleeper 6 of category B 70, a rail 1 of size UIC 60 with an inclination 1:40 to the middle of the track (to the left) is shown at its attachment point. (Fig. 1) The foot 2 of the rail 1 is tensioned by angle guide plates 5 in the lateral direction and from above by a resilient rail fastening 4. An elastic intermediate layer 8 is arranged between the bearing surface 21 of the concrete sleeper 6 and the rail foot sole 3, the lateral ribs 7, 9 of which are held by angle guide pieces 5.

The bottom view (arrow A) of the elastic intermediate layer is shown in Fig. 2. The upper side of the elastic intermediate layer, not shown, is flat and therefore has full contact with the rail foot sole 3.
The elastic intermediate layer 8 has within a largely closed edge strip, in the longitudinal direction of the rail with the parts 12, 13 and the transverse direction of the rail with the parts 10, 11, which enclose a recess surface 17. 42 compression points 18, which present themselves as elevations within the depression surface 17, are arranged within the depression surface 17. The total compression area between the rail foot sole 3 and the threshold 6, not shown, results from the total area of the edge strips 10-13 and the total area of the compression points 18. A thermoplastic, uncrosslinked elastomer was used as the material for the intermediate layer. The spring index achieved with a dimension of the intermediate layer of nominally 165 x 148 mm and a total thickness of 7 mm and a recess of 5 mm in this case is approx. 60 kN / mm at room temperature. On one side of the recess surface 10 drainage channels 20, 22 are guided across the edge strip, which allow air and / or water that has got into the recess surface to be pressed out of the recess surface 17 when the elastic intermediate layer is compressed. The drainage channels 20, 22 are arranged transversely to the rail, so that the suction from rolling vehicles cannot enter dust or water into the depression surface. If necessary, additional drainage channels can be arranged, for example, on the opposite edge strip. The radii 16 of the ribs 15, 40 encompass the sleeper body 6 and thus ensure a positive locking of the elastic intermediate layer 8 in the longitudinal direction of the rail. In the transverse direction of the rail, ie on the surface 21 of the sleeper 6, the lateral edge strips 10, 11 are protruded by ribs 9, 7 which, as shown in FIG. 1, can be clamped under the angle guide pieces 5. The protected fields 23 serve to identify the manufacturer and the date of manufacture of the intermediate layer.

FIG. 3 shows a section B-B according to FIG. 2, which in part leads through the edge strip 13 and the recess surface 17 with the knobs 18 and then (on the right partial image) shows a side view of the elastic intermediate layer 8. The ribs 14, 15 with the radii 16 serve to abut the threshold. The recess 17 extends from the edge strip 13, from which truncated pyramid-shaped compression points 18 with an inclined flank 19 protrude. The rib 9 in front of the edge strip 10 serves to fix the elastic intermediate layer, while the drainage channel 22 extends from the outer edge of the edge strip 10 to the recess surface 17 within the elastic intermediate layer.

FIG. 4 shows a second embodiment of an intermediate layer 25 analogous to FIG. 2, likewise in the position of view A according to FIG. 1. Instead of the compression points 18, here compression points 34, 30 of different sizes are used as truncated cones distributed over the recess surface 37. The intermediate layer 25 made of PE copolymers otherwise also has continuous edge strips 28, 29 for supporting the rail foot edges and reinforced, widened edge strips 26, 27 for reducing the specific edge pressure of the intermediate layer. The wrap-around strips 24 are reduced here to a minimum for fixing the intermediate layer on the threshold, for example to largely avoid an accumulation of material that is undesirable in terms of production technology. The compression points 30, 34 have a head surface 31, 37 which is reduced compared to their base surface 33, 35, so that an oblique flank 32, 36 results.
When the head surface 31, 37 is loaded, it increases in accordance with the flank angle and the compression path or the recess depth of the rail, not shown. The amount of depression, given the load and the nominal total compression area, can also be adjusted by the flank angle or thus influencing the spring stiffness.
With the size of the head surfaces 31, 37, number and distribution of the head surfaces over the intermediate layer 25, further parameters for setting the rigidity of the rail fastening are provided, the spring characteristic curve being relatively linear when using tapered compression points and progressive with pyramid-shaped points.

Claims (9)

1. Resilient rail fastening device with an elastic intermediate layer, located between a rail foot and a hard support, in which one surface is profiled, and the rail foot is clamped by a spring member, characterised in that only the surface (21) of the intermediate layer facing the support (6) is formed with a closed lateral strip (10-14; 26-29) which surrounds a recess surface (17, 37) from which a plurality of individual small-area compression points (18,30,34) project, the lateral strip and the compression points forming surface portions to be compressed.
2. Rail fastening device according to claim 1, characterised in that the resilient rigidity of the intermediate layer may be altered by altering the size of the respectively active compression surface (21,31,37), particularly of the compression points (18,30,34).
3. Rail fastening device according to claim 1 or 2, characterised in that the recess surface (17) of the intermediate layer is connected to at least one drain channel (20,22) in the lateral strip (10,11).
4. Rail fastening device according to one of claims 1 to 3, characterised in that the sum of the areas of the compression points (18,30,34) of the intermediate layer is less than half the recess surface (17,37).
5. Rail fastening device according to one of claims 1 to 4, characterised by compression points (18,30,34) whose head area (31,37) is smaller than their base area (33,35).
6. Rail fastening device according to one of the preceding claims, characterised in that the lateral strips (10-14; 26-29) of the intermediate layer are provided with ribs (7,9,14,15,24) for positive or frictional fixing on the support (6).
7. Rail fastening device according to one of the preceding claims, characterised in that there is used as a material for the intermediate layer (8,25) a thermoplastic elastomer (TPE) from the group of non-crosslinked rubbers, or an ethylene vinyl acetate copolymer (PE copolymer).
8. Rail fastening device according to claim 7, characterised in that the static resilience number of the intermediate layer is roughly 20 to 70 kN/mm when TPE is used, and roughly 130 kN/mm when PE copolymers are used at ambient temperature, for a loading frequency of > 50 Hz, preferably > 100 Hz.
9. Rail fastening device according to claim 8, characterised in that the static resilience number of the intermediate layer is < 30 kN/mm when TPE is used, and roughly 70 kN/mm when PE copolymer is used at ambient temperature, for a loading frequency of < 40 Hz.

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