Method for repairing a rail in a track

Abstract

The invention relates to a method for repairing a rail (4) in a track, which comprises: a) Removing a rail segment (12) between first and second portions (14, 16) of the rail (4) such that a first free end (18) of the first portion (14) is longitudinally facing a second free end (20) of the second portion (16); b) Moving the first end (18) towards an intermediate position (P11) in a direction perpendicular to the axis (X); c) Arranging, parallel to the axis (X), a replacement segment (22) comprising first and second ends (24, 26), the first end (24) of the segment (22) longitudinally facing the first end (18) of the first portion (14); d) Welding the first end (18) of the first portion (14) with the first end (24) of the segment (22); e) Positioning the second end (26) of the segment (22) so as to align it longitudinally with the second end (20) of the second portion (16) while keeping the first end (18) of the first portion (14) in the intermediate position (P11); and f) Welding the second end (20) of the second portion (16) with the second end (26) of the replacement segment (22).

Description

[0001] DESCRIPTION

[0002] TITLE: Method for repairing a rail on track

[0003] Technical field of the invention

[0004] This document concerns the execution of rail welding in railway track, particularly during construction, regeneration or maintenance work on tracks, especially when replacing a rail segment, for example, which has a defect.

[0005] Prior art

[0006] A railway track, which serves as a running and guiding track for railway vehicles, typically comprises two rails arranged parallel to each other along their length and fixed to supports or sleepers, for example, made of wood, concrete, metal, or synthetic materials, allowing for a constant gauge. The railway track rests on a base structure, ballasted or unballasted, which supports these sleepers and distributes the loads to the ground.

[0007] In the context of railway track maintenance, or the production of rail sections in the workshop, welding machines are used to weld rail sections in order to produce a continuous welded rail.

[0008] Welding can be carried out during the construction, regeneration or maintenance of railway tracks, or during the manufacture or integration of long welded rails (LWRs).

[0009] In particular, in the context of track maintenance, track welding is essential to replace rail segments, whether or not they have defects.

[0010] One of the challenges when replacing track rails is ensuring control of the thermal stresses present in the rails. For example, in France, track rails must exhibit a target thermal stress state corresponding to a reference track temperature, set between 25°C and 32°C.

[0011] Today, when track work or maintenance is carried out (preventive or corrective replacement, whether small or large-scale), the first step is to remove a rail segment. Following this removal, two rail sections are obtained, each with a free end. A replacement rail segment, intended to replace the removed segment, is then supplied and placed on the track. The replacement segment is slightly shorter than the removed rail segment. The replacement segment is then welded to the two free ends of the two rail sections using aluminothermic welding.

[0012] This aluminothermic welding process is preferred during construction and maintenance operations because it allows for the continuous joining of rails, including during the final phase of track joining, also known as track closure. This welding method involves filling the gap between the rails to be welded by pouring molten metal into a mold shaped like the rail, at the point where the two rail ends are joined.

[0013] This technique makes it possible to avoid varying the tension or compression stresses in the track during rail repairs.

[0014] However, this type of welding, which requires adding material between the two rail ends, does not offer good mechanical strength. Therefore, welding remains a weak point in the track today.

[0015] Other welding techniques allow for better mechanical strength of the rails on the track, but introduce tensile or compressive stresses within the rail. This is the case for the following welding techniques:

[0016] - electric flash butt welding (referred to as "flash butt welding" in English),

[0017] - electric induction (designated "induction welding" in English) and- gas under pressure.

[0018] Indeed, these welding techniques do not require the addition of material but involve a more or less significant consumption of part of the rail sections to be welded, thus increasing the stresses in the rail.

[0019] Induction welding proves particularly interesting, like gas pressure welding, because of the small movements of the rail ends (unlike flash welding which involves back and forth movements during the manufacturing process).

[0020] The purpose of this document is therefore to propose a complementary process to welding, adapted to track welding, while ensuring good quality of resulting weld and limiting the modification of internal stresses of the rails in the track.

[0021] Presentation of the invention

[0022] This document relates to a method for repairing a rail in track, said rail extending along a longitudinal axis, the method comprising: a) Taking a rail segment from said rail between a first portion of the rail and a second portion of the rail so as to obtain a first free end of the first rail portion arranged longitudinally opposite a second free end of the second rail portion; b) Moving said first end of the first portion to an intermediate position in a direction perpendicular to the longitudinal axis; c) Arranging, parallel to the longitudinal axis, a replacement segment comprising a first end and a second end, the first end of the replacement segment being arranged longitudinally opposite the first end of the first rail portion; d) Welding the first end of the first rail portion to the first end of the replacement segment;e) Position the second end of the replacement segment so as to align it longitudinally with the second end of the second portion while maintaining the first end of the first portion of the rail in said intermediate position.

[0023] In other words, the first end of the first section is no longer aligned longitudinally with the second end of the second rail section; f) Weld the second end of the second section with the second end of the replacement segment.

[0024] The method may include, following step f): g) Moving the first end of the first portion into the longitudinal alignment of the second end of the second portion. The first end may, in particular, be... The method allows for the replacement or insertion of a rail segment in track, for example, to replace a failed weld or a defective rail segment.

[0025] This process ensures that the stress in the rail meets the requirements set by national standards. Initially, after the segment is removed, the distance between the ends of the resulting rail sections is approximately equal to the longitudinal dimension of the removed rail.

[0026] The replacement segment used is longer than the segment removed, in preparation for the welding process which will consume material from the replacement segment. Therefore, the additional length is solely intended to compensate for material consumption during welding to the free ends of the rail sections.

[0027] The movement during step b) of the first end and the maintenance of this position of the first end after its welding with a first end of the replacement segment and during the welding of the second end of step f), ensures that the extra length of the replacement segment is consumed in the welding with the rails.

[0028] Such a process, as described in this disclosure, makes it possible to mitigate and compensate for the rail consumption required for induction, spark, or gas welding, and to limit or even prevent changes in thermal stresses in the track rails. Although under stress at the end of step f), the replacement segment is subsequently released from all stress when the first end is realigned with the second end; the repaired rail is then under a stress acceptable according to national standards.

[0029] The direction perpendicular to the longitudinal axis may be a transverse direction. The direction perpendicular to the longitudinal axis may be a vertical direction. The direction perpendicular to the longitudinal axis may have both a transverse and a vertical component.

[0030] Furthermore, step b) may be preceded by the following step:

[0031] - Place on the first rail segment a device capable of moving the first end of the segment in a direction perpendicular to the longitudinal axis and of holding said first end of the segment in said intermediate position. This involves placing a device capable of moving the first end such that the first end is no longer aligned with the second end. Thus, this device may consist of a retaining means and means, such as actuators, capable of exerting a force on the end in a direction perpendicular to the longitudinal axis. This force may be exerted in both directions. For example, the retaining means may be attached to the rail of the track not undergoing segment replacement, and actuators may be capable of moving the end of the segment away from the rail not undergoing segment replacement or moving it closer to it.

[0032] Step e) may be preceded by the following step:

[0033] - Place on the replacement segment a second device capable of moving the replacement segment in a direction perpendicular to said longitudinal axis.

[0034] The weld can be a weld with or without an insert.

[0035] Welding is preferably carried out without filler material, by consuming rail. The process can be performed on the track or in a workshop.

[0036] Welding can be performed using various methods, including induction welding, spark welding, or gas pressure welding. The removed rail segment may contain a defect.

[0037] Indeed, this rail repair method proves particularly suitable when repairing a rail following the appearance of a defect. The segment sampled can be chosen to encompass the defect(s), and since the steps of the process can be carried out on the track, it is possible to replace a defective rail segment with a replacement rail segment without defects.

[0038] Welding steps d) and f) may be followed by at least one of these two steps:

[0039] - a deburring step for the weld; and

[0040] - a grinding stage for the weld.

[0041] Indeed, these two steps allow for profiling the weld at the first and second ends with the replacement segment. During welding, excess metal appears around the weld, primarily due to material creep. The deburring step initially removes this excess metal roughly on both sides of the weld (along the longitudinal axis). Then, the grinding step eliminates surface defects, ensuring surface continuity between the first section, the replacement segment, and the second rail section. More specifically, the grinding step may include rough grinding followed by finishing grinding, often performed cold, to profile the weld according to geometric criteria defined by applicable federal, national, or regional standards.

[0042] The replacement segment may have a longitudinal dimension greater than the longitudinal dimension of the segment removed in step a). The longitudinal dimension of the replacement segment may be equivalent to the longitudinal dimension of the removed segment plus twice the longitudinal dimension of the material consumed during welding, the latter being determined based on the rail temperature immediately before welding. In other words, the longitudinal dimension of the replacement segment is greater than the longitudinal dimension between the first and second ends of the first and second sections.

[0043] The replacement segment may have a longitudinal dimension smaller than the longitudinal dimension of the segment taken in step a).

[0044] Thus, the additional dimension percentage of the replacement segment is intended for welding.

[0045] Moving the first end in a direction perpendicular to the longitudinal axis and holding it in position allows the replacement rail segment to be slightly bent during step e), so as to allow welding between the two ends.

[0046] Step a) may be preceded by the following step:

[0047] - Remove rail fixings on sleepers, arranged transversely to the rail, over a length greater than the segment taken in step a), for example greater than at least 30% than the segment taken in step a).

[0048] Step g) can be followed by a step of fixing the rail to the sleepers of the track in the same manner as the fixing present prior to step a).

[0049] Indeed, the rails that make up a track are held and fixed to sleepers, arranged transversely to the longitudinal axis. Thus, it is essential to detach the rail over a longitudinal length greater than the segment taken in step a), particularly to allow movement along the transverse direction of the first end.

[0050] This also ensures that, after electric spark welding, induction welding, or gas pressure welding, the stress in the rail meets the requirements set by the applicable standards.

[0051] Brief description of the figures

[0052] [Fig. 1] represents a railway track in which one rail has a defect; [Fig. 2] represents a preliminary step to the first step of the process in this document;

[0053] [Fig. 3] illustrates the first step of the process according to this document;

[0054] [Fig. 4] illustrates the second step of the process according to this document;

[0055] [Fig. 5] illustrates the third step of the process according to this document;

[0056] [Fig. 6] and [Fig. 7] illustrate the fourth step of the process according to this document; [Fig. 8] and [Fig. 9] illustrate the fifth step of the process according to this document; [Fig. 10] illustrates the sixth and seventh steps of the process according to this document;

[0057] [Fig. 11] illustrates a step that may follow the seventh step of the process according to this document;

[0058] [Fig. 12] represents a railway track obtained at the end of the process according to this document; [Fig. 13] represents a railway track in which one rail has a defect;

[0059] [Fig. 14] represents a preliminary step to the first step of the process in this document;

[0060] [Fig. 15] illustrates the first step of the process according to this document;

[0061] [Fig. 16] illustrates the second step of the process according to this document;

[0062] [Fig. 17] illustrates the third step of the process according to this document;

[0063] [Fig. 18] and [Fig. 19] illustrate the fourth step of the process according to this document; [Fig. 20] and [Fig. 21] illustrate the fifth step of the process according to this document; [Fig. 22] illustrates the sixth and seventh steps of the process according to this document;

[0064] [Fig. 23] illustrates a step that may follow the seventh step of the process according to this document;

[0065] [Fig. 24] represents a railway track obtained at the end of the process according to this document.

[0066] Detailed description of the invention

[0067] This document aims to propose a method for repairing a rail in track.

[0068] A track rail is a rail that makes up a railway track as illustrated by figures 1 and 13. A railway track 1 is thus made up of two rails 2, 4, arranged parallel to each other and to the longitudinal axis X, identified in figure 1.

[0069] These two rails 2 and 4 are arranged and fixed to sleepers 6. The sleepers 6 are arranged transversely to the longitudinal axis X and to the rails 2 and 4, and extend along the axis Y. These sleepers are made of wood, concrete, metal, or synthetic materials, to which the two rails of the track are fixed, thus ensuring that the rails are maintained at a constant gauge. The sleepers are arranged parallel to each other and to the axis Y, regularly spaced along the track.

[0070] Fasteners 8, such as rigid or elastic clips, are used to fix the rails 2 and 4 to the sleepers 6. Rail 4, in the illustrated example, requires the connection of a rail segment, for example, if it has a defect 10 requiring repair. This involves replacing a segment of rail 4 containing the defect 10 with a defect-free segment. This replacement requires, in addition to removing the segment with the defect, welding the replacement segment to rail 4.

[0071] Prior to the first step, a step is required to remove the rail fixings from the sleepers, as illustrated in Figures 2 and 14. As can be seen, the fixings 8 are removed over a length L1. This length L1 is chosen to allow at least partial mobility of the rail 4.

[0072] With reference to figures 3 and 15, the first step a) of the process aims to take a segment 12 of rail of said rail 4 between a first portion 14 of the rail and a second portion 16 of the rail.

[0073] The rail segment 12 is removed using a chainsaw. Thus, rail 4 is cut at the first end 18 of the first section 14 and at the second end 20 of the second section 16.

[0074] The length L2 of rail segment 12 in the illustrated example is 9m.

[0075] Preferably, the length L1, on which the fixings 8 of the rail 4 on the sleepers 6 have been removed, is greater by at least 33% than the length L2 of the segment 12 taken.

[0076] Following the sampling, we obtain a first portion 14 and a second portion 16, whose respective ends 18 and 20 are longitudinally opposite each other. Thus, the longitudinal space between the first end 18 and the second end 20 corresponds approximately to the length L2 of the sampled segment 12.

[0077] As can be seen, the segment sampled 12 includes the defect 10.

[0078] Said first 14 and second 16 rail sections extend along the longitudinal axis X, and said first end 18 and said second end 20 are opposite each other along the longitudinal axis X.

[0079] The process may include a second step aimed at arranging, parallel to the longitudinal axis X, a replacement segment 22 between the first portion 14 and the second portion 16.

[0080] The replacement segment 22 has a dimension L3 along the longitudinal axis X greater than the dimension L2 of the salvaged rail segment 12. In this example, the salvaged segment is 9.2 m long. Generally, the replacement segment 22 has a longitudinal dimension L3 greater by a certain value, defined by the rail type and the conditions at the time, than the longitudinal dimension L2 of the salvaged segment 12 in step A. Alternatively, the replacement segment 22 may have a longitudinal dimension L3 less than the longitudinal dimension L2 of the salvaged segment 12 in the first step a). The replacement segment 22 comprises a first end 24 and a second end 26 intended to be welded respectively to the first end 18 and second end 20 of the first and second rail sections, respectively.

[0081] Thus, the replacement segment 22 is arranged between rail 2 and rail 4, parallel to the longitudinal axis, such that the first end 24 of the replacement segment 22 is substantially aligned in a direction perpendicular to the longitudinal axis with the first end 18 of the first portion 14.

[0082] The next step in the process involves movements of the first and second ends in a direction perpendicular to the longitudinal axis. Specifically, this direction perpendicular to the longitudinal axis X can correspond to a transverse direction Y (as shown in Figures 4 to 10), a vertical direction Z (as shown in Figures 16 to 22), or a direction with both a transverse and a vertical component. To achieve this, as can be seen in Figures 4 and 16, devices 28 and 30 are arranged on the first rail section 14 and the replacement segment 22.

[0083] Devices 28, 30 are capable of moving a portion of rail by translation along a given direction and of maintaining the portion of rail in a desired position.

[0084] In general, the device 28, 30 may include two elements 28a, 28b and 30a, 30b on the portion or more elements if appropriate, to allow uniform translation of the rail portion.

[0085] These devices can be adapted to move the rail in order to achieve the desired curvature. This facilitates the management of the positioning of the rail ends.

[0086] Thus, a first device 28 is placed on the first section 14 of rail near the first end 18 of the first section 14.

[0087] The first device 28 is thus able to move the first end 18 of the first portion 14 along the direction perpendicular to the longitudinal axis X and to maintain said first end 18 of the first portion 14 in an intermediate position P1.

[0088] A second device 30 is arranged on the replacement segment 22. The second device 30 is thus able to move the replacement segment 22 in a direction perpendicular to the longitudinal axis X.

[0089] Each element 28a, 28b and 30a, 30b of devices 28, 30 may include an actuator, capable of exerting a force on the lateral faces of the first portion 14 of rail or of the replacement segment 22.

[0090] The force exerted can be in either direction along the perpendicular axis X, by means of a movable part. Each element 28a, 28b and 30a, 30b further includes a retaining means suitable for attachment to rail 2. Elements 28a, 28b and 30a, 30b may also include passive rail positioning control means, such as a pressure cylinder. The positioning of elements 28a, 28b and 30a, 30b and the spacing between elements 28a, 28b and 30a, 30b are adapted, in particular, according to the track configuration, such as the track's inclination and curvature, and the type of rail.

[0091] The third step b) of the process aims to move the first end 18 of the first portion 14 along the direction perpendicular to the longitudinal axis X towards an intermediate position P11.

[0092] As shown in Figures 5 and 17, the end 18 of the first portion 14 of the rail is moved to a position P11 distinct from the initial position P10. For this purpose, the actuators of the device 28 are activated so as to exert a force F1, illustrated by an arrow in Figures 5 and 17.

[0093] Since the rail remains fixed to the sleepers 6, outside the length L1, the first portion 14 curves slightly, so as to form a wave, this is visible in figures 5 and 17. Thus, the end 18 of the first portion 14 is brought closer, by means of the device 28, to the end 24 of the replacement segment 22.

[0094] The order of magnitude of the displacement of the end 18 of the first portion 14 (corresponding to the distance between position P11 and initial position P10) can be determined according to the type of rail.

[0095] Before the fourth step d), an intermediate step c) aims to move the replacement segment 22 from the initial position P20 to a position P21.

[0096] For this purpose, the actuators of the device 30 are activated so as to exert a force F2, illustrated by an arrow in figures 6 and 18. This allows, as illustrated in figures 6 and 18, that the first end 24 of the replacement segment 22 and the first end 18 of the first portion 14 are longitudinally opposite each other for the purpose of welding them.

[0097] Thus, in this position, despite the length L3 of the replacement rail 22 being greater than the space between the first end 18 of the first portion 14 and the second end 20 of the second portion 16, the replacement rail 22 can be welded to the first end 18 of the first portion without the second end 26 of the replacement segment 22 interfering with the second portion 16.

[0098] The fourth step d), illustrated in figures 7 and 19, aims to weld the first end 18 of the first portion 14 of rail with the first end 24 of the replacement segment 22.

[0099] For this purpose, a welder 32 is positioned above the ends 18 and 24. In this example, it is an induction electric welder. This welding is therefore carried out without an insert or the addition of material. Indeed, during induction welding, a portion of the replacement segment 22 is consumed, for example, a length of approximately 25 mm.

[0100] The new weld 34, illustrated in Figures 8 and 20, is then subjected to deburring operations, followed by grinding. These two steps allow the weld 34 to be deburred, in order to ensure that the weld 34 has a continuous surface with the replacement segment 22 and the first portion 14. Thus, deburring aims to remove excess molten metal present at the periphery of the weld 34, and grinding aims to reduce the asperities around and on the weld 34.

[0101] The fifth step e), illustrated in figures 9 and 21, aims to position the second end 26 of the replacement segment 22 in the direction perpendicular to the longitudinal axis X so as to align it longitudinally with the second end 20 of the second portion 16 while maintaining the first end 18 of the first portion 14 of the rail 4 in said intermediate position P11.

[0102] As can be seen, the actuators of the device 30 are activated so as to exert a force F3 on the rail and to move the end 26 of the replacement segment 22 to the position P22. This allows, as illustrated in figures 9 and 21, the second end 26 of the replacement segment 22 and the second end 20 of the second portion 16 to be longitudinally opposite each other for welding.

[0103] Maintaining the first end 18 at the intermediate position P11 allows the replacement segment 22 to be bent, so that despite the size of the replacement segment 22, there is no collision between the end 20 of the second portion 16 and the second end 26 of the replacement segment 22.

[0104] The undulation of the rail therefore makes it possible to reduce the replacement segment 22 by a length which corresponds to the length of rail to be consumed when welding the ends 20 and 26 and to the length of rail necessary to ensure zero rail stress at the reference temperature.

[0105] The sixth step f) aims to weld the second end 20 of the second portion 16 with the second end 26 of the replacement segment 22.

[0106] This sixth step is illustrated in figures 10 and 22, and as for the fourth step, an electric induction welder 32 is used, and positioned above the ends 20 and 26 to be welded.

[0107] The weld 36 obtained is subjected to the same deburring and grinding operations, as described in relation to weld 34.

[0108] Step seven (g) aims to move the first end 18 of the first section 14 into longitudinal alignment with the second end 20 of the second section. Thus, the ends 18, 20, 24, and 26 are aligned along the longitudinal axis X. As shown in Figures 10 and 22, the actuators of device 28 are activated so that the end 18 of the first section 14 is returned to its initial position P10. Rail 4 thus regains its original shape and stress, complying with applicable standards. The former position of the rail, before the activation of the actuators of device 28, can be seen in the same figures as a dashed line. Figures 11 and 23 therefore illustrate track 1 at the end of step seven (g) of the process.

[0109] Following this, the repaired rail 4 is reattached to the sleepers. The fasteners 8 are repositioned on the sleepers 6 of track 1 in the same way as the fasteners 8 were present before the steps of the process, as illustrated in Figures 12 and 24.

Claims

DEMANDS 1. Method for repairing a rail (4) in track, said rail (4) extending along a longitudinal axis (X), the method comprising: a) Taking a rail segment (12) from said rail (4) between a first portion (14) of the rail (4) and a second portion (16) of the rail (4) so ​​as to obtain a first free end (18) of the first portion (14) of rail arranged longitudinally opposite a second free end (20) of the second portion (16) of rail; b) Moving said first end (18) of the first portion (14) to an intermediate position (P11) in a direction perpendicular to the longitudinal axis (X);c) Arrange, parallel to the longitudinal axis (X), a replacement segment (22) comprising a first end (24) and a second end (26), the first end (24) of the replacement segment (22) being arranged opposite longitudinally the first end (18) of the first rail section (14); d) Weld the first end (18) of the first rail section (14) to the first end (24) of the replacement segment (22); e) Position the second end (26) of the replacement segment (22) so as to align it longitudinally with the second end (20) of the second section (16) while maintaining the first end (18) of the first section (14) of the rail (4) in said intermediate position (P11); f) Weld the second end (20) of the second section (16) to the second end (26) of the replacement segment (22).

2. A method according to claim 1, wherein step c) is preceded by step: - To place on the first section (14) of rail a first device (28) capable of moving the first end (18) of the first section (14) in the direction perpendicular to the longitudinal axis (X) and of maintaining said first end (18) of the first section (14) in said intermediate position (P11).

3. A method according to claim 1 or 2, wherein step e) is preceded by step: - To place on the replacement segment (22) a second device (30) capable of moving the replacement segment (22) in a direction perpendicular to said longitudinal axis (X).

4. A method according to any one of the preceding claims, wherein the welding is carried out without the addition of material, such as, for example, induction welding (or any other welding process with forging) 5. A method according to any one of the preceding claims, wherein the rail segment taken (12) includes a defect (10).

6. A method according to any one of the preceding claims, wherein the welding steps d) and f) are followed by at least one of these two steps: - a deburring step for the weld; and - a grinding stage for the weld.

7. A method according to any one of the preceding claims, wherein the replacement segment (22) has a longitudinal dimension (L3) greater than the longitudinal dimension (L2) of the segment taken (12) in step a).

8. A method according to any one of the preceding claims, wherein the replacement segment (22) has a longitudinal dimension (L3) less than the longitudinal dimension (L2) of the segment taken (12) in step a).

9. A method according to any one of the preceding claims, wherein step a) is preceded by the following step: - Remove fasteners (8) from the rail (4) on sleepers (6), arranged transversely to the rail (4), over a length (L1) greater than the length (L2) of the segment taken (12) in step a).

10. Method according to claim 9, wherein step g) is followed by a step of fixing the rail (4) to the sleepers (6) of the track with fixings (8) in the same manner as the fixing present prior to step a).

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