METHOD FOR FIXING A RAIL OF A RAIL TRACK WITH THERMAL CONDITIONING OF A RAIL PORTION, AND ASSOCIATED RAIL MACHINE

Abstract

In order to fix a rail of a rail track using a rail machine, the rail machine is moved in a working direction so that at all times a portion of the rail which is not attached to a cross-member of the rail track passes through a thermal conditioning zone of a thermal conditioning device of the rail machine, a temperature of a surface region of the portion of the rail passing through the thermal conditioning zone is modified using the thermal conditioning device by generating a non-homogeneous temperature distribution in the portion of the rail, and the portion of the rail is fixed to a cross-member of the rail track, after modification of the temperature of the surface region of the portion of the rail, without waiting for the temperature distribution in the portion of the rail to be homogenized.

Claims

1. A method of immobilizing a rail of a railway track by means of a rail machine, comprising: moving the rail machine in a work direction, such that, at each moment, a portion of the rail not fixed to a sleeper of the railway track passes through a thermal conditioning zone of a thermal conditioning device of the rail machine; a temperature of a surface region of the portion of the rail passing through the thermal conditioning zone is changed by means of the thermal conditioning device, by generating a non-homogenous temperature distribution in the portion of the rail; wherein the portion of the rail is fixed on a sleeper of the railway track after the temperature of the surface region of the portion of the rail has been changed, but without waiting for the temperature distribution in the portion of the rail to be homogenized.

2. The method of claim 1, wherein the portion of the rail is fixed to the sleeper less than 50 seconds after the portion of the rail has left the thermal conditioning zone.

3. The method of claim 1, wherein the change in the temperature in a surface region of the portion of the rail passing through the thermal conditioning zone is such that an average temperature of the portion of the rail at an outlet of the thermal conditioning zone is within +/−5° C. of a predetermined setpoint temperature of a laying location.

4. The method of claim 1, wherein the change in the temperature in a surface region of the portion of the rail passing through the thermal conditioning zone results in a transfer of an amount of heat equal to the amount of heat required for bringing a section of rail, under adiabatic conditions, to a homogenization temperature equal to a temperature in a predetermined tolerance range of −5° C. around a predetermined setpoint temperature.

5. The method of claim 1, wherein the portion of the rail passing through the thermal conditioning zone is raised with respect to the railway track.

6. The method of claim 1, wherein the portion of the rail passing through the thermal conditioning zone rests on a sleeper of the railway track.

7. The method of claim 1, wherein the temperature of a surface region of the portion of the rail passing through the thermal conditioning zone is changed by means of heat exchange with a heat source, hot or cold, by thermal radiation, thermal conduction, and/or convection.

8. A rail machine, comprising: at least one thermal conditioning device comprising at least one thermal conditioning zone; traction means for moving the rail machine in a work direction at a predetermined operating speed, said predetermined operating speed being in a range between 100 and 1200 m/hour, such that, at each moment, a portion of the rail that is not fixed to a sleeper passes through the thermal conditioning zone; the thermal conditioning device being capable of changing a temperature in a surface region of the portion of the rail passing through the thermal conditioning zone by means of the thermal conditioning device, by generating a non-homogeneous temperature distribution in the portion of the rail; an immobilization zone of the portion of the rail on a sleeper of a railway track, located behind the thermal conditioning zone in the work direction, wherein the immobilization zone is positioned such that, at the predetermined operating speed, a distance between the immobilization zone and the thermal conditioning zone is travelled in less than 170 seconds.

9. The rail machine of claim 8, wherein the thermal conditioning device is capable of supplying to the portion of the rail passing through the thermal conditioning zone, and/or extracting from the portion of the rail passing through the thermal conditioning zone, a higher amount of heat which is sufficient for increasing and/or decreasing, by at least 5° C., an average temperature of the portion of the rail, for a U1C60 rail, when the rail machine advances in the work direction at the predetermined operating speed.

10. The rail machine of claim 8, wherein the rail machine comprises means for changing the temperature of a surface region of the portion of the rail passing through the thermal conditioning zone, via an alternating electrical current induced or conducted in the portion of the rail.

11. The rail machine of claim 8, wherein the rail machine comprises means for changing the temperature of a surface region of the portion of the rail passing through the thermal conditioning zone by heat exchange with a heat source, hot or cold.

12. The method of claim 1, wherein the temperature of a surface region of the portion of the rail passing through the thermal conditioning zone is changed by means of heat exchange with a heat source, by thermal radiation, thermal conduction, and/or convection.

13. The method of claim 1, wherein the temperature of a surface region of the portion of the rail passing through the thermal conditioning zone is changed by means of an alternating electrical current induced or generated in the portion of the rail.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0056] Other features and advantages of the invention will become clear from the following description, given with reference to the accompanying drawings, in which:

[0057] FIG. 1 is a schematic view of a site for laying a rail of a railway track according to the method of the invention;

[0058] FIG. 2 is a schematic detailed view of the site of FIG. 1, showing the thermal conditioning and the fixing of a portion of rail according to the method of the invention;

[0059] For reasons of improved clarity, identical or similar elements are indicated by identical reference signs in all the figures.

DETAILED DESCRIPTION OF EMBODIMENTS

[0060] FIG. 1 is a global view of a site for replacing a railway track 2, a site on which, by means of a replacing train 4 (shown in part), old rails 6 (front sector) and old sleepers 8 are deposited and are replaced by new sleepers 10 and new rails 12, all this being carried out continuously as the replacing train 4 advances, at a constant speed in a work direction 100. The replacing train 4 comprises wagons 16 resting on bogies 18, 20 which roll on the old rails 6 in the front part of the replacing train 4 and on the new rails 12 in the rear part of the replacing train 4. A mid-part of the replacing train 4 in turn rests on caterpillar tracks 22 which, in the absence of rails on the track 2 in this part of the site, roll directly on the ballast 24 and the old sleepers 8 before they are deposited.

[0061] On a front portion of the site, tools make it possible to separate the old rails 6 from the sleepers 8. Gradually, during their disassembly, the old rails 6 are raised and placed down on the ballast 24 on the sides of the track. On the front portion of the site, the old sleepers 8 are exposed, which makes it possible to continue to the deposition thereof by means of a group of deposition tools, and to the replacement thereof by the new sleepers 10 by means of a group of laying tools. The new rails 12 which, prior to the passage of the replacing train 4, were arranged on the ground on either side of the track 2, on wheels in order to allow for thermal dilation of the rail free of stress towards the front of the train, are raised and positioned, adhering to the desired geometry of the track 2, before being laid on the new sleepers 10. The immobilization of the new rails 12 is achieved by the weight of the rail machine in the region of the immobilization zone 26, also referred to as the anchoring zone, located in the region of a bogie 20, in the rear part of the replacing train 4. In a known manner, the actual fixing of the new rails 12 is performed downstream, by means of fasteners.

[0062] In order to prevent or limit the risk of deterioration of the track under the effect of variations of climatic or meteorological conditions, it is provided for the new or restored rails 12 to be fixed on the sleepers, by bringing said metal profiles to a setpoint temperature, referred to as “neutral.”

[0063] For this purpose, the portion of new or restored rail to be laid 12 is brought to a setpoint temperature in a thermal conditioning zone 30 of a thermal conditioning device 32, the thermal conditioning zone 30 being located upstream of and close to the immobilization zone 26 of the rail on one or more sleepers 10, or even directly adjacently to the immobilization zone 26. If applicable, the actual immobilization zone 26 can be preceded by a rail positioning zone which may be located between the thermal conditioning zone 30 and the immobilization zone 26 (in the event of the rail being raised in the thermal conditioning zone) or upstream of the thermal conditioning zone (in the event of the rail already resting on the new sleepers 10 in the thermal conditioning zone 30). Alternatively, the positioning zone of the rail coincides with the immobilization zone 26 or the thermal conditioning zone 30.

[0064] When the intervention on the site takes place at a moment when the ambient temperature is lower than the setpoint temperature referred to as “neutral,” the thermal conditioning comprises heating of the rail, the thermal conditioning device 30 is converted into a heating device, the thermal conditioning zone 30 thus being a heating zone. Said heating can be carried out by the means typically used, which have in common the characteristic that they do not generate a homogeneous distribution of the temperature in the rail, but on the contrary bring about a significant temperature difference between particular heated zones at the surface of the rail or in the vicinity of the surface of the rail, and the less heated zones located in the center of the rail. The heating can in particular be achieved by electrical induction into the rail, by spraying of hot water, by infrared radiation, or by exposure to heat transfer fluid (water, air, vapor, combustion gas, flame).

[0065] Vice versa, when the ambient temperature is greater than the setpoint temperature referred to as “neutral,” the thermal conditioning comprises cooling of the rail, the thermal conditioning device 30 is converted into a cooling device, the thermal conditioning zone 30 thus being a cooling zone. Said cooling can in particular be achieved by means of exposure to a heat transfer fluid.

[0066] Notably, the immobilization zone 26 is positioned, with respect to the thermal conditioning device 32, such that when the replacing train 4 advances in the work direction 100 at a nominal operating speed, the portion of the rail that left the thermal conditioning device 32 having a non-homogeneous temperature distribution reaches its immobilization position on the sleeper in the immobilization zone 26 before homogenization of the temperature distribution, in a transverse cross section of the rail portion, has taken place.

[0067] By way of example, the immobilization zone 26 is located at least five meters form the thermal conditioning zone 30, for a replacing train travelling at a nominal speed of 500 m/hour, such that a portion of the rail reaches the immobilization zone 26 less than 36 seconds after emerging from the thermal conditioning zone 30.

[0068] In practice, it is of interest to reduce, as far as possible, the distance between the output of the thermal conditioning zone 30 and the immobilization zone 26, in order to simplify the restarting of the replacing train 4 after a period of stoppage, by reducing the rail portion of which the temperature is no longer in the tolerance interval allowing the anchoring thereof, and located between the thermal conditioning zone 30 and the immobilization zone 26. It is thus provided in particular for the output of the thermal conditioning zone 30 to be able to coincide, spatially, with the immobilization zone 26.

[0069] Thermometers 34 are positioned at the input of the thermal conditioning zone 30, inside the thermal conditioning zone 30, at the output of the thermal conditioning zone 30, and, if applicable, directly in the vicinity of the immobilization zone 26. Said thermometers 34 are connected to a control unit 36 which receives signals of other sensors 38 such as, for example: a speed sensor of the replacing train 4, a speed sensor of the rail to be processed, an ambient temperature sensor, an atmospheric pressure sensor, and/or an ambient humidity sensor. The control unit 36 is thus capable of measuring, estimating or calculating one or more of the following parameters: an average temperature of the portion of the rail to be processed prior to thermal conditioning, an average temperature of the portion of the rail after the thermal conditioning, a temperature of the portion of the rail during the thermal conditioning, a temperature of the portion of the rail after anchoring thereof, an external ambient temperature, a movement speed of the replacing train 4, a movement speed of the rail with respect to the thermal conditioning device, an amount of heat transmitted to the portion of the rail by the thermal conditioning device.

[0070] Furthermore, the control unit 36 contains, in a memory, a setpoint temperature which may have been acquired or programmed, and is representative of the neutral temperature sought in the immobilization zone 26, which makes it possible, if applicable, to determine a deviation between the setpoint temperature and an average temperature of the portion of the rail to be processed, before thermal conditioning, a deviation between the setpoint temperature and an average temperature of the portion of the rail after thermal conditioning, or a deviation between the setpoint temperature and an average temperature of the portion of the rail during the thermal conditioning. In a known manner, the control unit 36 is suitable for modulating the power of the thermal conditioning device.

[0071] When the replacing train 4 advances in a work direction 100, the rail to be processed 12 moves, with respect to the thermal conditioning device 30, in the opposite direction, and is guided such that, at every moment, a raised portion of the rail to be processed 12 passes through the thermal conditioning zone 30. If applicable, the positioning of the thermal conditioning device is adjusted by means of actuators or a positioning mechanism.

[0072] It is thus ensured that, at every moment and depending on the advancement of the replacing train 4, a portion of the rail to be processed 12 passes through the thermal conditioning zone 30 where, according to the extreme conditions, it is heated or cooled by the thermal conditioning device 32 such that the average temperature in the portion of the rail at the output of the thermal conditioning zone is equal to the setpoint temperature. The control unit 36 determines, by means of a calculation algorithm, on the basis of all or some of the parameters discussed above, the thermal energy which has to be transferred to the rail to be processed 12 or which has to be extracted, in order to obtain said average temperature.

[0073] From the output of the thermal conditioning zone 30, and although the temperature thereof is very inhomogeneous, the portion of the rail 12 has reached the extension corresponding to the extension of a rail at a homogeneous temperature that is equal to the setpoint temperature. The portion of the rail to be processed 12 penetrates, immediately or almost immediately, into the immobilization zone 26, where it is subsequently fixed onto a sleeper 10 of the railway track, less than 50 seconds, and preferably less than 30 seconds after emerging from the thermal conditioning zone 30. In this short time lapse, the losses due to convective exchange with the ambient air are negligible.

[0074] Of course, the examples shown in the drawings and discussed above are given merely by way of example and are non-limiting.

[0075] The mode of thermal conditioning of the rails which has been described for a renovation of the railway track, replacing rails, also applies for a renovation of the track replacing old rails, or for first laying, or indeed for thermal maintenance treatment.

[0076] What has been describe for a replacing train can be transferred to an autonomous rail machine or a laying train.