EP0864015B1 - Sleeper for a railway track - Google Patents

Description

The invention relates to sleepers for railway.

The traditional sleepers for railways are usually made of wood. next a more recent design, they are made of concrete armed mono-block or double block. We also know metal sleepers, used mainly in tropical countries.

The wooden sleepers are from a point of view very interesting technique as long as we stay in the elastic range of wood. Wood offers in particular excellent vibration damping qualities caused by the passage of vehicles on the rails.

However, the wooden sleepers pose currently an environmental issue. We demand, in fact, to make the sleepers, a wood of high quality (old oak or beech). This poses, in view of the extremely large quantities required, problems with availability and preservation of the environment.

In addition, this wood must be treated so that it withstands atmospheric conditions, which poses other problems (duration of treatment, nature of products but above all strike the unit price of the sleepers. If we lower these demands on treatment, we faced with a sustainability problem, so that despite its high cost, the crosspiece must be periodically replaced.

US Patent 1,418,708 shows that, very early on, we sought to improve the cost and longevity of sleepers a railway. The cross member described in this patent has a wooden body enclosed by straps metallic. It is coated with a composite layer asphalt and asbestos. This cross shape classic parallelepiped, has a coating layer vulnerable to outside agents and is ultimately polluting. This cross is not particularly resistant to mechanical stress.

Concrete sleepers are currently very widespread as a substitute for wooden sleepers. We use generally sleepers made up of two blocks in reinforced concrete, also called blocks, connected by a metal spacer. The essential advantage of these sleepers lies in their relatively low cost price.

However, concrete sleepers provide generally poor amortization performance of vibrations and their mechanical qualities are degraded enough quickly, making it necessary for the sake of safety, quick replacement of track sleepers rail, and this all the more frequently as convoys railways run there at high speed.

There is therefore a problem of medium cost and long term. The relatively low cost, upon purchase, of concrete sleepers cannot compensate for the increase the cost of replacement operations and equipment specific used for this purpose.

The metal sleepers, meanwhile, are noisy at high speed and the electrical insulation of rails can only be made at the cost of special equipment. The metal crosspiece is more expensive than the wood.

These considerations have led to an increasing number of researchers to move towards making sleepers made of synthetic or composite materials, with results so far very unsatisfactory.

In addition, high synthetic materials quality have a very high cost price.

Document EP-A-0 560 580 describes sleepers of epoxy resin railway in which were incorporated fragments from recycled tires, which therefore contain rubber, steel wire, fibers various unsorted synthetics. This type of material, for not very homogeneous, and containing particles may rust, cannot be used as a base for long-lived railway sleepers.

The document EP-A-0 154 259 describes a sleeper railway track which has a metal frame coated with resin containing in addition to rubber fragments, a mixture of sand and stony debris.

Such a cross especially takes up the stresses by its frame; there are problems of connection between the body and the reinforcement and it cannot therefore also not be considered for long sleepers lifetime.

We also know from EP-A-0 486 465 a crosspiece with chipboard panels and a metal frame in box, coated with foam polyurethane. The rigidity is mainly due to the metal box structure, the chipboard having here a role of filling material. The upper side of the cross is flat. The structure of this cross is very different from the one considered here.

US-A-4,105,159 describes a cross composed of high density wooden elements made of particles of agglomerated wood, and wooden elements of frame, joined, sandwiched between the elements of high density made up of agglomerated wood particles. The preservation of such a cross is dependent on the incorporation of toxic and polluting preservatives.

The sleepers described in the patent US-A-4,286,753 have a wooden body possibly composed of several elements of wood, lying flat on the entire length of the crosspiece. A plurality of sheets plates are arranged above and below the body and possibly between the different elements of the body. These sheets are composed of chipboard and resin. A resin is used as a bonding medium, to bond the leaves to the body of the crosspiece.

Resin sheets prevent wooden body to split into pieces and thus prolongs the service life of the crossing. But the problem of processing the wood itself persists.

In US-A-1,623,185 is described a sleeper made using old recycled sleepers. The cross is made up of layers of shredded wood, saturated with a binder and a waterproofing material such as asphalt; metal reinforcements, in the form of metal nets are arranged between each of these layers of wood. The crossmember also has a plate made of metal on its upper face and on its lower face. These sleepers have the known disadvantages of metal apparent such as the need for protection against rust, noise and the need for insulation electric.

In patent FR-2,134,930, there is described a railway sleeper which includes an elongated body of synthetic resinous composition molded from a single room. This one-piece molded crosspiece has inclined portions, constituting seats for the rails. The synthetic resinous composition is very expensive despite the possible incorporation of fillers such as shavings Of wood.

We tried to develop track sleepers new type of rail, particularly resistant to mechanical and aging stresses, which must not therefore more to be replaced than at very long intervals and / or which resist stresses particularly high for large convoy traffic speed.

One of the aims of the invention is to reduce the pressure on the forest environment by reducing the felling of noble species.

The subject of the present invention is a cross-member for railway track, which includes a core and a outer casing. The core of this crosspiece includes at least one blade of wood (By blade of wood, we mean a solid or natural wood blade as opposed to a material reconstituted from particles or shavings of agglomerated wood). This cross has two shoulders concrete or polymer concrete, located at the ends longitudinal of the cross member above the core. The part upper of these shoulders is able to receive rail fasteners. The outer envelope at least partially surrounds the crosspiece.

According to a first embodiment of the invention the core consists of a single blade of wood, for example from an old railway cross traditional in high quality wood, downgraded.

According to another embodiment of the invention, the core consists of several blades of wood, preferably laid on edge.

The shoulder comprises, according to a mode particular embodiment of the invention, concrete polymer, made up, in particular, of sand and gravel, as filler and of a binder chosen from polyurethane, epoxy and polyester.

According to another preferred embodiment of the invention, the shoulder comprises concrete (sand and cement).

According to a particular embodiment of the invention, the shoulder comprises a sole which can be, for example, a T-shaped steel plate. ethyl vinyl acetate (EVA) plate is then advantageously, placed between the sole and the rail.

In particular, the upper side of each shoulder is located in an inclined plane with respect to the plane in which the nucleus is located, the highest point of each inclined plane being located at the ends of the crosses.

According to a particular embodiment, the sleeper core has filler material between certain wooden boards. This filling material can be, for example, a composite material comprising a resin.

According to particular embodiments, the core blades are joined to each other by gluing and / or stapling. This has the advantage of allowing manipulation of the nucleus as a single object, without running the risk that the wooden slats do not move compared to others.

According to an advantageous embodiment of the invention, the cross member comprises, in the part under the shoulder and between the wooden boards that extend over the entire length of the core, end blocks which have a height greater than the so-called wooden blades.

Advantageously, the cross member comprises, between the shoulders, a central part having, in section vertical, in essence the shape of a convex pentagon. In particular, this pentagon has a bottom side in essence horizontal, and is symmetrical with respect to the perpendicular bisector longitudinal of said lower side.

The cross member may advantageously include a layer of polymer between the core and the shoulder.

According to particular embodiments of the invention, the envelope comprises a polymer which is chosen, for example, from polyester, polyurethane or epoxy. The envelope may also include filler, chosen, for example, from rubber vulcanized or recycling products such as debris recycled tires. The envelope can be further reinforced by reinforcing fibers, chosen, for example, from glass fibers, carbon fibers, or fibers aramid.

According to an advantageous embodiment of the invention, the crosspiece has a finishing layer applied to the outer surface of the envelope polymer. This top coat may include a dye.

la Fig. 1 est une vue en perspective d'une traverse suivant l'invention;

la Fig. 2 est une coupe longitudinale partielle d'une traverse selon la ligne II-II de la Fig. 1;

la Fig. 3 est une coupe transversale selon la ligne III-III de la Fig. 1;

la Fig. 4 est une coupe transversale selon la ligne IV-IV de la Fig. 1;

les Figs. 5 et 6 sont des vues en perspective de deux variantes d'exécution du noyau de la traverse;

la Fig. 7 est une coupe transversale similaire à celle de la Fig. 3, le noyau étant réalisé selon la variante d'exécution représentée à la Fig. 6;

la Fig. 8 est une coupe similaire à celle des Figs. 3 et 7, d'une variante d'exécution;

la Fig. 9 est une coupe longitudinale partielle similaire à celle de la Fig. 2, d'une variante d'exécution.

La figure 10 est une vue en coupe longitudinale partielle d'une variante de la traverse suivant l'invention.

La figure 11 est une vue en coupe transversale suivant le plan XI-XI de la figure 10.

Different examples of execution are described below, reference being made to the appended drawings in which:

Fig. 1 is a perspective view of a crosspiece according to the invention;

Fig. 2 is a partial longitudinal section of a cross member along the line II-II of FIG. 1;

Fig. 3 is a cross section along line III-III of FIG. 1;

Fig. 4 is a cross section along the line IV-IV of FIG. 1;

Figs. 5 and 6 are perspective views of two alternative embodiments of the core of the crosspiece;

Fig. 7 is a cross section similar to that of FIG. 3, the core being produced according to the alternative embodiment shown in FIG. 6;

Fig. 8 is a section similar to that of FIGS. 3 and 7, of an alternative embodiment;

Fig. 9 is a partial longitudinal section similar to that of FIG. 2, of an alternative embodiment.

Figure 10 is a partial longitudinal sectional view of a variant of the crosspiece according to the invention.

FIG. 11 is a cross-sectional view along the plane XI-XI of FIG. 10.

Figure 1 shows a cross 1 according to the invention. It has two shoulders 2 located at longitudinal ends of the cross member 1. These shoulders 2 have a sole 9 at their upper part suitable for receiving rail fasteners (not represented). Between the two shoulders 2, a part central 3 is provided; its height is less than that that the cross member 1 has at the shoulders 2.

Figures 2 and 3 show in more detail the shoulder 2 of a cross member 1 according to the invention. It is made of concrete or polymer concrete 8, which incorporates as filling material for gravel and sand, and as binding a resin. This resin is preferably polyurethane, it can also be epoxy or polyester. We will preferably choose a resin with rapid hardening, which advantageously accelerates the making sleepers 1.

These shoulders 2 have as essential function the capture and distribution of compression tensions which are transmitted to the body of the sleeper.

The shoulder 2 has an upper face inclined in the longitudinal direction; its lowest point is on the side of the central part 3 and its point the higher is on the side of the end of the cross-member 1. In most European countries, the inclination recommended is 1/20; sometimes (for example in Germany) it is 1/40. Nothing prevents to choose another tilt as it would be required by the regulations railways. This inclination has the advantage of promote good wheel-rail contact and get the best part of the structure of the crosspiece according to the invention.

As seen in Figures 2, 3 and 4, the cross member 1 has a core 4 composed of wooden blades 5 laid on edge which extend over the entire length of the said crosspiece 1 with their fibers parallel to the axis of said cross member 1. These blades 5 preferably have a dimension of about 5 centimeters wide and about 12 centimeters in height. Thus, the core 4, having a total width of about 30 centimeters, is composed of five wooden blades 5 (Figs. 3 and 4).

The association of wooden core 4 and shoulder 2 in concrete plays a decisive role in increasing performance achieved by the crosspiece according to the invention.

When cross member 1 is subjected to stresses resulting from the passage of a vehicle rail, the core-shoulder junction zone merges practically with a neutral fiber, above which the shoulder 2 resumes the compressive stresses (ideal characteristic for concrete), however the wooden core 4 is stressed in tension.

An advantage is, moreover, that one can use less expensive types of wood (i.e. young wood either wood from old downgraded sleepers) than in a classic cross member, and for a good service life bigger.

The wood used for this core 4 is in principle made up of species considered, a priori, to be of lesser quality. Indeed, it is not necessary to resort to high quality wood (old oak or beech). The mechanical characteristics of pine, for example, are more than enough to absorb the stresses mechanical (tension in elongation and resistance to bending) which are distributed in a distributed way to the nucleus 4 by the shoulders 2. The core 4 in turn ensures good damping of oscillations, which is also one of the advantages of the present invention. The next cross 1 the invention has, in fact, characteristics better damping than conventional sleepers solid wood or concrete.

We can obviously also depending on the course and market availability use sustainable wood as old oak or beech. We can also use for core 4 of the old downgraded sleepers of which cut the impregnated outer part (see figs 10 and 11). In this case we do a special recycling interesting for the environment. Only the layer exterior, impregnated, cut, should be treated as industrial waste. Furthermore, the noble wood recovered resumes a new career for which he is particularly suitable, without new punctures are necessary on the forest mass.

As seen in Fig. 4, the part central 3 of the cross member 1 present, in cross section, the shape of a convex pentagon. This one has a side lower horizontal, and is symmetrical with respect to the mediator of said lower side. The central part 3 has two slopes at its upper part which avoid stagnation of water (rain or runoff).

The whole of sleeper 1, except the sole 9, is coated with a polymer envelope 6 (Figs. 2, 3, 4, 7, 9). The envelope 6 has substantially the same thickness everywhere (about 2 to 4 cm). Can also consider making it a little thicker at the party crosspiece 1, to reduce the risk of perforation by the ballast on which the sleepers are placed or on the contrary interrupt the envelope in this part which is not subjected to the aging effect of UV.

In an alternative embodiment shown in FIGS. 8, 10, 11, the envelope 6 is not complete at the level of the shoulders 2. The upper part of shoulder 2 is not not covered by the envelope 6.

The envelope 6 has the function of protecting, from effectively and almost unlimited in time, the structure [core 4 + shoulder 2] and more particularly nucleus 4, atmospheric conditions and effects of pressure on the track ballast. She'll have advantageously a practically elastic behavior.

It is possible to strengthen the envelope of polymer 6 by adding fibers to the resin enhancement.

The envelope 6 comprises a polymer, preferably polyurethane, for example polyurethane called "gelcoat". It is possible to strengthen possibly envelope 6 by adding to the polymer reinforcing fibers.

Filler, such as rubber vulcanized, in irregularly shaped pieces (coming from example of recycled tires, stripped of their threads can also be added to the polymer. Outraged its insulating qualities, rubber has the advantage in particular increase the flexibility of the envelope 6.

Here, we also recycle a raw material into making the best use of its intrinsic qualities.

Given the dissociation of mechanical functions respective shoulders and core it is important that we have excellent adhesion between these two parts of the sleeper.

In Figures 2 and 3, there is shown also a sole 9, partially buried in the envelope 6 and in the concrete or polymer concrete 8. The face upper of the sole 9 is preferably located in the same plane as that of the upper face of the shoulder 2. The sole 9 is not in contact with the wood. She presents, in cross section, the shape of a T (Figs. 3 and 7).

In the variant shown in Fig. 8, the sole 9 is buried directly in the concrete 8, so that the upper face of the sole 9 is located in the same plane as that of the face upper shoulder 2.

The sole 9 is suitable for receiving organs of fixing a rail. These fasteners can be chosen from all available types.

The sole 9 serves, in concert with the shoulder 2 corresponding, to distribute the pressures exerted by the rails on sleeper 1 when a train is passing. The sole 9 is larger here than the soles classics.

We can predict, but this is not shown in the figures, put between the sole 9 and the rail a ethyl vinyl acetate (EVA) plate to muffle noise produced by the rail / sole contact.

The presence of such soles is however optional. We can also replace them with fixings for rails which are then embedded in the concrete of shoulders (see Figs 10, 11).

FIG. 5 shows an alternative embodiment of the core 4 of the cross member 1. One in two of the wooden blades which make up the core 4, are made in one piece, and extend over the entire length of the core 4. These blades then bear the reference 5. These blades 5 allow ensure good resistance of the cross member 1 to traction and bending.

The intermediate blades, located between the blades 5, consist of three parts: two blocks end 10, the length of which corresponds substantially to the length of the shoulders 2, and a complementary blade 11, the length of which corresponds substantially to that of the central part 3. In the case illustrated in FIG. 5, the height of the end blocks 10 and of the blade complementary 11 is equal to that of the blades 5.

According to another variant, shown in Figs. 6 and 7, the end blocks 10 are replaced by blocks 12 of the same width and length as blocks 10, but whose height is greater than the height of the blades 5. This embodiment gives good joining between the shoulder 2 and the core 4.

According to an alternative embodiment, shown in FIG. 6, the interval between two end blocks 12 is occupied by a filling material. According to a mode advantageous in execution, this filling material is a composite material incorporating a resin, which is preferably the same resin as that of the envelope polymer 6. It is obvious that a filling material will be advantageous if, with mechanical performance equal, it is cheaper than wood.

It goes without saying that the different variants of execution may be combined. Material filling could also replace the blade complementary 11, in the case of FIG. 5.

Blocks 10 or 12 and additional boards 11 or the filling material, are introduced if necessary primarily to lower the price return cost of cross member 1.

According to another embodiment of the crosspiece 1 shown in FIG. 9, shoulder 2 and core 4 are separated by a layer 13 comprising a polymer identical to the polymer used for envelope 6. The upper face of the shoulder 2 always has the same inclination.

The advantage of this embodiment is the the concrete 8 and the core 4 are completely separated. The water which would penetrate into the concrete 8, for example by the place where the sole 9 is fixed, will not attack the core 4 since it is protected by layer 13. This mode advantageously can be combined with that of the Fig. 8 where the casing 6 does not extend to the upper face shoulder 2.

Figs 10 and 11 show an embodiment comparable to that of FIG. 9: the shoulders 2 are there separated from the core 4 by a layer of polymer material 13. Fastening means for rail 14 other than the flanges 9 (here, threaded studs) are partially embedded in the concrete of the shoulders 2. These fixing means 14 could in particular be "pig tails" or the like.

The core 4 is formed here from a piece of wood unique, for example, as described above top, of a classic recycled crosspiece.

The sleepers according to the invention can be manufactured by means known to those skilled in the art and in particularly by molding. Molding can be done advantageously in a vacuum or pressure mold.

The cross-member can be made, for example, by two stages: the core and the shoulder are made in first and then the envelope is die casting.

The trapezoidal shape of the crosspiece allows, in addition, an easy release.

Claims (17)

1. Railway sleeper (1) which comprises a core comprising at least one wooden strip (5) and an outer casing (6), characterized in that the sleeper (1) has two concrete or polymer concrete shoulders (2) located at the longitudinal ends of the sleeper (1) above the core (4), the upper part of these shoulders (2) being capable of taking members for attaching a rail, and in that the casing (6) at least partially surrounds the sleeper (1).
2. Sleeper (1) according to the preceding claim, characterized in that the upper face of each shoulder (2) is in a plane which is inclined with respect to the plane in which the core (4) is located, the uppermost point of each inclined plane being at the ends of the sleeper (1).
3. Sleeper (1) according to the preceding claim, characterized in that the shoulder (2) includes a T-shaped steel plate (9).
4. Sleeper (1) according to any one of the preceding claims, characterized in that between the shoulders (2) it includes a central part (3) which, in vertical section, is substantially in the shape of a convex pentagon, having a substantially horizontal bottom face and being symmetric with respect to the longitudinal mid-point of the said bottom face.
5. Sleeper (1) according to any one of the preceding claims, characterized in that it includes a layer (13) of polymer between the core (4) and the shoulder (2).
6. Sleeper (1) according to any one of the preceding claims, characterized in that the casing (6) includes a polymer chosen from polyester, polyurethane and epoxy.
7. Sleeper (1) according to Claim 6, characterized in that the casing (6) furthermore contains filler material.
8. Sleeper (1) according to Claim 7, characterized in that the filler material is chosen from vulcanized rubber or recycling products such as recycled tyre debris.
9. Sleeper (1) according to any one of Claims 6 to 8, characterized in that the casing (6) also includes reinforcing fibres chosen from glass fibres, carbon fibres and aramid fibres.
10. Sleeper (1) according to any one of the preceding claims, characterized in that the core (4) is made up of several wooden strips (5), at least one in two of which span the entire length of the core (4).
11. Sleeper (1) according to Claim 10, characterized in that the wooden strips (5) of which the core (4) is composed, are laid edge-on.
12. Sleeper (1) according to either one of Claims 10 and 11, characterized in that the core (4) includes packing material between certain wooden strips (5).
13. Sleeper (1) according to any one of Claims 10 to 12, characterized in that the strips of the core (4) are joined together with adhesive bonding.
14. Sleeper (1) according to any one of Claims 10 to 13, characterized in that the strips of the core (4) are joined together by stapling.
15. Sleeper (1) according to any one of Claims 10 to 14, characterized in that, in the part under the shoulder (2) and between the wooden strips (5) which span the entire length of the core (4), the sleeper includes end blocks (12) which are taller than the said wooden strips (5).
16. Sleeper (1) according to any one of Claims 1 to 9, characterized in that the core (4) is made of an old conventional wooden railway sleeper, the impregnated outer part of which has been removed.
17. Sleeper (1) according to any one of the preceding claims, characterized in that it includes a finishing coat.

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