EP0837969B1 - Method and device for mounting track rails - Google Patents

Abstract

PCT No. PCT/BE97/00055 Sec. 371 Date Dec. 30, 1997 Sec. 102(e) Date Dec. 30, 1997 PCT Filed Apr. 30, 1997 PCT Pub. No. WO97/42376 PCT Pub. Date Nov. 13, 1997In a device for fixing a rail resting on a support by means of an anti-vibration pad, a prestress is applied to this pad so that the operating point of the anti-vibration pad (2) always remains in the region of linear behaviour of the said anti-vibration pad in order to limit the static rail deflections while providing the desired anti-vibration isolation.

Description

The present invention is in the field of support devices for railroad tracks. She relates more particularly to a fixing method of rail.

Current rail fasteners include at least one sole made of elastic material which gives elasticity to the wheel / rail assembly so that either obtained a certain vibration isolation from the forces dynamic towards the environment.

There is almost always an elastic stage (sole fairly rigid) directly below the rail. There is often a second, softer sole below a metal saddle or cross member. This last sole provides anti-vibration insulation.

The first bending resonance frequency of the wheel / rail assembly is conditioned by the stiffness dynamic soles. This resonant frequency is inversely proportional to the anti-vibration performance of the rail fastening system: a frequency low resonance gives better insulation anti-vibration than a high resonant frequency.

With soles that have low dynamic stiffness, we reduce the first resonant frequency of the whole wheel / rail, which gives a good filter anti-vibration. The best filter is therefore obtained with the lowest dynamic stiffness of the soles.

There is, however, a lower physical limit than this dynamic stiffness of the soles used in the systems rail fasteners. Dynamic stiffness is directly related to the static stiffness of soles. The static stiffness of the soles cannot be too weak because it directly influences rail deflection when passing vehicles on rails. This deflection of the rails is generally limited to approximately 3 mm. For most devices the current resonant frequency is between 35 Hz and 60 Hz.

This limit of static deflection of the rail imposes a minimum static stiffness, and thus dynamic stiffness minimum of the sole. This phenomenon limits anti-vibration isolation performance of systems rail fasteners.

To achieve superior insulation performance to that obtained with conventional fastening systems, we have to completely decouple the functions of fixing and insulation: this is done in floating type systems where the rails are fixed on a slab which itself is isolated from the environment by anti-vibration pads between the slab and write it off (or ground). For a floating slab, the resonance frequency is between 10 Hz and 25 Hz approximately, which gives a better anti-vibration filter. These latter systems are however very expensive, and difficult to maintain.

The object of the present invention is to provide devices fixing rail insulation performance anti-vibration close to those obtained with a floating slab and at the same time ensuring good rail stability.

This objective is achieved according to the invention by a rail fixing method and device such as defined in the claims. We apply to the anti-vibration sole elastic preload which changes the operating point of the anti-vibration soleplate so that it is always kept in the linear behavior zone of said sole anti-vibration under the effect of a charge circulating on the rail. When a wheel passes over the rail above of a fixing device, the load becomes greater, but the anti-vibration sole continues to operate in its linear behavior zone. The static deflections of the rail are thus limited while ensuring the desired anti-vibration insulation. The process according to the invention thus provides for fixing of the rail a high apparent static stiffness with low dynamic stiffness.

In the device according to the invention, the sole anti-vibration is pre-stressed using springs so that the operating point of the anti-vibration soleplate is always kept in the linear behavior zone of said sole anti-vibration under the effect of a charge circulating on the rail.

The invention is explained in more detail in the description which follows with reference to the accompanying drawings.

Figure 1 shows a typical rail fixing device.
Figure 2 shows a static deflection curve typical of an anti-vibration sole.

1. selle métallique

2. semelle anti-vibratoire sous selle (éventuellement sous traverse)

3. semelle anti-vibratoire sous rail

4. crapaud d'attache

5. bouton d'ancrage

6. ressort

7. isolation électrique

8. rail

9. béton, bois, acier, etc.

Referring to FIG. 1, a typical rail fixing device with two elastic stages comprises the following members:

1.metal saddle

2. anti-vibration sole under saddle (possibly under cross member)

3. anti-vibration sole under rail

4. attachment toad

5. anchor button

6. spring

7. electrical insulation

8. rail

9. concrete, wood, steel, etc.

1. une zone non-linéaire de mise en charge (A),

2. une zone linéaire dans laquelle le produit doit fonctionner (B),

3. une zone non linéaire, non exploitable (C).

The anti-vibration soles have a static deflection curve as shown in Figure 2. On this curve there are three areas:

1. a non-linear loading area (A),

2. a linear zone in which the product must operate (B),

3. a non-linear, non-exploitable area (C).

It is important to work continuously in the area linear product of the fact that the real charge is quasi-static and fast (wheel arch). Of this way we avoid to pass each time in the zone not linear loading.

According to the invention, when fixing a rail on gives the anti-vibration sole 2 a preload such that sole 2 always works in its zone linear behavior (area B in Figure 1).

Significant prestressing (some ten thousand N) applied to the sole is created by two or four springs that apply preload to the sole anti-vibration between the saddle or cross member and the raft. This prestress can also be created by the toads in the case of a fastening system to a single elastic stage.

It should be noted that there are already fixing systems of elastic two-stage rail with springs but whose sole purpose is to mechanically hold the saddle or crosses it in place and allow deflection from the saddle. Prestressing on these springs is only a few thousand N.

According to the invention, on the basis of the data track and rolling stock techniques, the rail fixing device is defined in primarily taking into account insulation performance anti-vibration (or resonant frequency wheel / rail) requested. These performances require generally a weak dynamic stiffness.

From this dynamic stiffness we derive the static stiffness requested (depending on the material of the sole). With this static stiffness, we generally arrive at large static rail displacements, not tolerated. We give a prestress to the sole which is such that the difference between moving the front rail prestressing and after prestressing remains less than tolerated movement of the rail (generally 3 mm). Preferably, the sole is chosen in such a way that it works in its linear zone with prestressing and the extra load that comes on when passage of a wheel.

For a rail fixing system type UIC 60 on concrete, 60 cm travel, unsprung mass vehicle weight of 1000 kg, an axle load of 180 kN and a resonant frequency of the wheel assembly / 22 Hz rail (insulation similar to floating slab), we need a dynamic stiffness of the sole elastic in the fastening system of about 10 kN / mm (calculation by the finite element method).

Using a product with equal static stiffness at dynamic stiffness, we get a deflection of the 4.5 mm rail with the axle load considered.

If a prestress of the order of 30 kN is given to the sole, which corresponds to about 3 mm of deflection, rail deflection when passing the wheel is of the order of 1.5 mm, which is entirely acceptable. The system nevertheless remains very flexible dynamically.

Claims (4)

1. A method for mounting a track rail on a support structure (9), the rail (8) being fixed on a metal sole-plate (1) resting on an anti-vibration pad (2), characterized by placing under the metal sole-plate (1) an anti-vibration pad made of a compound having a static stiffness and a dynamic stiffness substantially equal, fixing the sole-plate (1) and the anti-vibration pad (2) on the support structure (9) by means of adjustable spring fastening devices comprising each a spring (5, 6), and adjusting the adjustable fastening devices to apply to the anti-vibration pad (2) a preload stress of at least 10kN approximately, the pad being subjected to a preload so that the operating point of the anti-vibration pad (2) always remains in the region of linear behaviour of said anti-vibration pad under the effect of a load running over the rail.
2. A method according to claim 1, characterized in that the adjustable spring fastening devices (5, 6) are adjusted to apply to the anti-vibration pad (2) a preload stress equal to about 30 kN.
3. A support device for track rail comprising a metal sole-plate (1) resting on an anti-vibration pad (2), first fastening means (4) fixing the rail (8) on the sole-plate (1) and second fastening means (5, 6) fixing the sole-plate (1) and the anti-vibration pad (2) on the support structure (9), characterized in that the anti-vibration pad (2) is made of a compound having a static stiffness and a dynamic stiffness substantially equal, and in that the second fastening means (5, 6) are adjustable spring fastening devices comprising each a spring, the adjustable spring fastening devices (5, 6) applying a preload stress of at least 10 kN approximately, the pad being subjected to a preload so that the operating point of the anti-vibration pad (2) always remains in the region of linear behaviour of said anti-vibration pad under the effect of a load running over the rail.
4. A support device for track rail according to claim 3, characterized in that a second anti-vibration pad (3) is placed between the rail (8) and the metal sole-plate (1).

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