Method for repairing a railway rail by means of a repair mould

Abstract

A method for repairing a railway track running rail (1), said running rail (1) extending longitudinally along an axis (X) and vertically along an axis (Z), said running rail (1) having an upper portion (11) adapted to be in contact with a wheel of a railway vehicle, which has at least one damaged area, the method comprising: - a step of removing the damaged area so as to form a recess (4) in the upper portion (11) of the running rail (1), said recess (4) having, in a longitudinal cross-sectional plane (X, Z), a concave profile (40) comprising successively a first curved portion (41), a longitudinal portion (42) and a second curved portion (43); - a step of placing a mold around the recess (4); and - a step of filling the mold with liquid metal so as to fill said recess (4) and thus repair said running rail (1).

Description

GENERAL TECHNICAL FIELD AND PRIOR ART

[0001] The present invention relates to the field of repairing a running rail of a railway track.

[0002] A railway track conventionally comprises longitudinal running rails connected by transverse sleepers made of wood or concrete which rest on the ground. In a known manner, two consecutive running rails are connected by welded joints. A joint has the disadvantage of creating a discontinuity between the running rails, which is a source of shocks and prematurely increases the wear of the running rails. In order to eliminate this disadvantage, it has been proposed to limit the number of joints by forming very long running rails, known to those skilled in the art under the designation LRS (Long Rail Welded) rails.

[0003] As a reminder, in reference to the Figure 1, a running rail 1 comprises: a lower part 13, designated “shoe”, adapted to rest on the ground, an upper part 11, designated “mushroom”, adapted to be in contact with a wheel of a railway vehicle along an upper surface 14 designated “rolling table”, and an intermediate part 12, designated “web” which connects the upper part 11 to the lower part 13. Such a running rail 1 is known to those skilled in the art and will not be presented in more detail. As illustrated in Figure 1 , the circulation rail 1 extends longitudinally along an X axis, laterally along a Y axis and vertically along a Z axis so as to form an orthogonal reference frame (X, Y, Z).

[0004] Due to the regular passage of railway vehicles, the head 11 of a running rail 1 may comprise a damaged zone ZE (whether or not impacting the running table 14), which affects its behavior. In a known manner, the repair method depends on the size of the damaged zone. When the damaged zone ZE is large, greater than a track-keeping limit threshold known to those skilled in the art, the damaged portion of the running rail is removed and replaced by a new longitudinal portion known to those skilled in the art as a “coupon”. During the repair, the new longitudinal portion must be welded to the existing longitudinal portions of an LRS rail, which increases the number of weld joints and has the aforementioned drawbacks. The performance of the LRS rail is then degraded.

[0005] In order to avoid the systematic replacement of a longitudinal portion, a repair method using aluminothermy has been proposed in the prior art. With reference to the Figure 1 , this repair method proposes to remove a damaged area ZE located at the head 11 of the running rail 1 (impacting or not the running table 14) by making a recess 2, 3 in the running rail 1. Then, a mold (not shown) is placed around the recess 2, 3 in order to allow the pouring of liquid metal into the mold and, consequently, the filling of the recess 2, 3. The damaged area ZE of the head 11 of the running rail 1 is thus replaced by an area free of defects formed from the cast metal. In other words, the running rail 1 has a “dressing” made from the cast metal.

[0006] As is well known, always with reference to the Figure 1, the recess 2, 3 made in the head 11 of the running rail 1 is in the form of a notch which can be of different dimensions and shapes. The notch can be either circular 2 or rectangular 3 in shape. A notch is said to be “circular” when the profile of the recess 2, 3 in the longitudinal plane of the running rail 1, that is to say, the plane (X, Z), has the shape of an arc of a circle.

[0007] In practice, the circular notch 2 is obtained by cutting metal (local oxidation) using a template allowing a circular cut. Such a cut is precise but its length is limited to 90 mm, which presents a first drawback. A circular notch 2 does not allow the removal of a damaged area that is deep. Indeed, as illustrated in Figure 2, the vertical distance P2 between the rolling table 14 and the bottom of the circular notch 2 is variable over the length of the notch 2, which does not allow a damaged zone ZE of great length to be removed in the depth of the mushroom 11. In other words, the notch length is variable at a given depth.

[0008] To eliminate this inconvenience, with reference to the Figures 1 and 2, it has been proposed to produce a rectangular notch 3 in order to allow the removal of a damaged area ZE that is deep. A notch is said to be "rectangular" when the profile of the recess 3 in the longitudinal plane of the running rail 1, that is to say, the plane (X, Z), consecutively has a vertical flank 31, a horizontal flank 32 and a vertical flank 33. In practice, a rectangular notch 3 has a maximum length of 55 mm, which limits its application. In addition, a rectangular notch 3 is obtained by grinding, which is time-consuming and increases the repair cost. Furthermore, grinding defects may appear at the intersection of the flanks. Patent application GB802256 presents such a rectangular notch.

[0009] Finally, with reference to the Figure 3, during the repair of the running rail 1, very high temperature liquid metal M is poured into the rectangular notch 3, which causes the appearance of a melting zone ZF in the rail head 11 at the profile of the rectangular notch 3. Such a melting zone ZF, also called a melted zone, allows the liquid metal M added in the rectangular notch 3 to mix with the existing metal of the running rail 1 in order to form a good quality weld. In practice, the melted zone ZF must be as large as possible in order to ensure good weld strength. As illustrated in Figure 3 , for a rectangular notch 3, the melted zone ZF is not of constant width and is, in particular, thinner near the ends of the horizontal flank 32 of the profile of the rectangular notch 3, which can affect the robustness over time of such a weld.

[0010] Documents EP2808446A1 and FR2266570 also concern the repair of a running rail of a railway track.

[0011] One of the objectives of the present invention is to propose a new repair method which makes it possible to overcome the aforementioned drawbacks while being simple to implement. GENERAL PRESENTATION OF THE INVENTION

[0012] For this purpose, the invention relates to a method for repairing a railway running rail according to claim 1.

[0013] Thanks to the longitudinal portion of the recess profile, a deep and long damaged area can be removed in a manner similar to a rectangular notch. Advantageously, the curvilinear portions allow for a wide fusion zone to be obtained when filling the mold with liquid metal, which guarantees a robust weld over time. Preferably, the fusion zone has a width of at least 3 mm.

[0014] Preferably, the recess has a depth configured to maintain a residual thickness of the upper part of the rail of between 6 and 10 mm. The depth is adapted to the profile of the running rail.

[0015] Preferably, the recess has a total length of between 126 and 140 mm, preferably of the order of 130 mm. The total length is defined at the level of the upper surface, i.e., the running surface. Such a recess is suitable for removing a damaged area of ​​great depth, which avoids replacing a damaged portion of the rail with a new portion.

[0016] Advantageously, the length of the longitudinal portion of the recess is between 50 mm and 80 mm. Such a recess makes it possible to remove a damaged area which is elongated in depth in the manner of a rectangular notch.

[0017] Preferably, the radius of curvature of each curvilinear portion of the recess is between 40 mm and 44 mm, preferably of the order of 42 mm. Thus, the melted zone has a significant thickness.

[0018] Preferably, at least one curvilinear portion is a portion of a circular arc of constant radius of curvature. Such a curvilinear portion makes it possible to form a melted zone of significant and regular thickness along the curvilinear portion, which improves robustness. More preferably, each curvilinear portion is a portion of a circular arc of constant radius of curvature. Preferably, the radii of curvature of the curvilinear portions are equal.

[0019] Such removal is analogous to removal for a circular notch. Thus, the person skilled in the art can perform such removal quickly and accurately.

[0020] Preferably, the recess is symmetrical with respect to a plane transverse to the axis along which the running rail extends. Thus, the running rail is repaired homogeneously, which improves the robustness of the weld.

[0021] Preferably, the step of removing the damaged area comprises at least the following three phases: a first phase of withdrawal by means of a first template allowing a circular cut whose radius of curvature corresponds to that of the first curvilinear portion, a second phase of withdrawal by means of a second template allowing a circular cut whose radius of curvature corresponds to that of the second curvilinear portion, and a third phase of withdrawal so as to form the longitudinal portion of the profile of the recess.

[0022] The removal step makes it possible to produce the curvilinear portions in a manner analogous to a circular notch. Advantageously, the template according to the prior art can be retained. Preferably, the first two removal phases are carried out by oxycutting and then repeated by grinding. Preferably, the third removal phase is carried out by grinding. Thus, the recess has a homogeneous surface condition.

[0023] According to a preferred aspect, a single template is used to form the two curvilinear portions successively. Alternatively, a single template allows the recess to be formed in a single removal step.

[0024] Such a mold is suitable for guiding liquid metal into a recess as presented previously in order to obtain a quality repair.

[0025] This application also describes a running rail extending longitudinally along an X axis and vertically along a Z axis, said running rail comprising an upper part adapted to be in contact with a wheel of a railway vehicle, the upper part comprising at least one new zone formed by filling with liquid metal a recess in said upper part, said recess having, in a longitudinal sectional plane (X, Z), a concave profile successively comprising a first curvilinear portion, a longitudinal portion and a second curvilinear portion. PRESENTATION OF THE FIGURES

[0026] The invention will be better understood by reading the following description, given solely by way of example, and referring to the appended drawings in which: there Figure 1is a schematic perspective representation of a running rail having a damaged area, a circular notch and a rectangular notch; Figure 2 is a longitudinal sectional view of the notches of the Figure 1 ; there Figure 3 is a schematic representation of a molten zone when pouring liquid metal into the rectangular notch; Figure 4 is a schematic perspective representation of a running rail with a damaged area; Figure 5 is a schematic perspective representation of a running rail having an oblong-shaped recess; Figure 6 is a longitudinal sectional view of the recess of the Figure 5 ; there Figure 7 is a schematic representation of an example of the formation of a recess; figure 8 is a schematic representation in longitudinal section of an assembly of a running rail and a mold; the Figure 9is a schematic perspective representation of a set according to the figure 8 ; and the Figure 10 a schematic representation in longitudinal section of a running rail after repair.

[0027] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate. DESCRIPTION OF ONE OR MORE METHODS OF EMBODIMENT AND IMPLEMENTATION

[0028] A method of repairing a railway track rail according to an embodiment of the invention will now be presented.

[0029] As a reminder, in reference to the Figure 4, a running rail 1 comprises: a lower part 13, designated “shoe”, adapted to rest on the ground, an upper part 11, designated “mushroom”, adapted to be in contact with a wheel of a railway vehicle along an upper surface 14 designated “rolling table”, and an intermediate part 12, designated “web” which connects the upper part 11 to the lower part 13. Such a running rail 1 is known to those skilled in the art and will not be presented in more detail. As illustrated in Figure 4 , the circulation rail 1 extends longitudinally along an X axis, laterally along a Y axis and vertically along a Z axis so as to form an orthogonal reference frame (X, Y, Z). In this example, the circulation rail 1 comprises at least one damaged zone ZE formed in its upper part 11.

[0030] A damaged zone ZE corresponds to a portion of rail whose upper part 11 contains at least one defect (affecting or not the running surface 14) whose dimensions can reach or even exceed a value called the “track-keeping limit threshold” known to those skilled in the art. Preferably, the “track-keeping limit threshold” corresponds to a damaged zone ZE whose length is 80 mm and / or whose depth is 15 mm. The defects of a damaged zone ZE can take various forms, in particular a sagging and / or a widening of the running surface 14, localized impacts, horizontal cracks or plunging cracks propagating into the depth of a running rail 1. Step of removing the damaged area

[0031] In reference to the Figure 5, the repair method comprises a step of removing the damaged area ZE so as to form a recess 4 in the upper part 11 of the running rail 1. According to the invention and with reference to the Figure 6 , said recess 4 has, in a longitudinal sectional plane (X, Z), a concave profile 40 successively comprising a first curvilinear portion 41, a longitudinal portion 42 and a second curvilinear portion 43. By abuse of language, such a recess can be considered as an “oblong” notch. The longitudinal portion 42 extends horizontally, that is to say, parallel to the rolling table 14.

[0032] As shown in the Figure 6, the recess 4 has a total length L1 of between 126 and 140 mm, preferably of the order of 130 mm. The length L2 of the longitudinal portion 42 of the recess 4 is between 50 and 80 mm. Preferably, the ratio of the length of the longitudinal portion 42 to the total length L1 is between 36% and 64% so as to allow removal of a damaged zone ZE of significant length in depth of the running rail 1 in the manner of a rectangular notch. Preferably, the recess 4 has a depth P1 configured to retain a residual thickness of the upper part of the rail of between 6 and 10 mm.

[0033] Preferably, the radius of curvature of each curvilinear portion 41, 43 of the recess 4 is between 40 and 44 mm, preferably of the order of 42 mm. In this example, the radii of curvature of the curvilinear portions are equal so that the recess has a plane of symmetry. Each curvilinear portion 41, 43 corresponds to a portion of a circular arc of constant radius of curvature. However, the invention also applies to curvilinear portions having different radii of curvature and different angular ranges in order to be able to adapt to damaged zones ZE of different shapes.

[0034] Preferably, the recess 4 is produced, at least in part, by means of a template which makes it possible to follow the profile 40 of the recess 4. In this example, with reference to the Figure 7 , the damaged area ZE is removed in three phases: a first phase of withdrawal by means of a first template 61 allowing a circular cut whose radius of curvature R3 corresponds to that of the first curvilinear portion 41, a second phase of withdrawal by means of a second template 62 allowing a circular cut whose radius of curvature R4 corresponds to that of the second curvilinear portion 43, and a third phase of withdrawal so as to form the longitudinal portion 42 of the profile of the recess 4.

[0035] In this example, the removal phases using a template 61, 62 are carried out by an oxycutting method known to those skilled in the art in order to obtain precise and rapid removal. The removal of the material between the areas cut by oxycutting is preferably carried out by grinding in order to directly guarantee a surface condition free from impurities linked to the cutting method. The curvilinear portions 41, 43 can also be taken up by grinding.

[0036] The recess 4 is formed in a practical manner similar to a circular notch according to the prior art. Following the formation of the recess 4, with reference to the Figure 7 , the mushroom 11 of the running rail 1 advantageously comprises at least a residual height h of 8 mm, preferably between 6 and 10 mm, in order to allow the formation of a melted zone of significant width to obtain an optimal weld as will be presented later. In this example, a single and same template is used successively to produce the two curvilinear portions 41, 43.

[0037] According to one aspect of the invention, a single, suitably shaped template can be used to remove the entire damaged area, thereby speeding up the removal step. For this purpose, the template has an oblong profile. Step of setting up a mold

[0038] In reference to the figures 8 And 9, the method further comprises a step of placing a mold 5 around the recess 4. The general structure of such a mold 5 is known to those skilled in the art.

[0039] The mold 5 comprises an internal cavity 50 adapted to follow the curvature of said circulation rail 1 and ensure its sealing during the flow of the liquid metal. As illustrated in Figure 9 , the mold 5 has an upper opening 56 allowing access to said internal cavity 50.

[0040] In reference to the figure 8 , the mold 5 comprises a lower part 52, adapted to be positioned at the level of the web 12 of the circulation rail 1, an upper part 53, adapted to be positioned above the upper surface 14 of the circulation rail 1 and an intermediate part 54 adapted to be positioned at the level of the mushroom 11 in order to form a lateral envelope for the recess 4.

[0041] The intermediate part 54 of the mold 5 comprises at least one imprint 7 comprising a concave profile 70 successively comprising a first curvilinear portion 71, a longitudinal portion 72 and a second curvilinear portion 73. Such an imprint 7 advantageously makes it possible to cooperate by complementarity of shapes with the profile of the recess 4 to form an enclosure of calibrated shape to receive the liquid metal.

[0042] In this embodiment, the upper part 53 of the mold 5 further comprises a conduit 55 of generally trapezoidal shape and flared vertically upwards so as to allow optimal guidance of the liquid metal in the enclosure formed by the mold 5 and the recess 4 and to direct the solidification towards the top of the mold 5. Similarly, the intermediate part 54 of the mold 5 comprises vents 57 in order to allow the gases generated during welding to escape.

[0043] In this example, with reference to the Figure 9 , the mold 5 comprises two mold members 51 which are complementary and adapted to be positioned laterally to the circulation rail 1 to be repaired. The mold members 51 are positioned on the circulation rail 1 and locked in position, preferably, by means of a vice or the like so that the mold 5 is watertight. In this example, each mold member 51 comprises an imprint 7 as presented previously. It goes without saying that the mold 5 could have a different structure. Filling step

[0044] The repair method also includes a step of filling the mold 5 with liquid metal so as to fill said recess 4 and thus repair said circulation rail 1. In practice, the liquid metal, at very high temperature, is poured into the upper opening 56 of the mold 5 and fills the recess 4.

[0045] The liquid metal poured into the mold 5 causes the metal of the circulation rail 1 to melt, in particular, the first curvilinear portion 41, the longitudinal portion 42 and the second curvilinear portion 43 of the profile 40 of the recess 4. The metal of the parts 11, 12, 13 of the circulation rail 1 also melts, at least partially.

[0046] A fusion zone appears at the profile 40 of the recess 4 and comprises a mixture of poured liquid metal and existing liquefied metal of the running rail 1, thus forming a robust weld. Due to the shape of the recess 4 and, in particular, its curvilinear portions 41, 43, the melted zone has a significant thickness, preferably greater than 3 mm. The melted zone also makes it possible to reduce any residual defects. Preferably, the liquid metal is steel whose composition approaches the grade of the running rail 1 to be repaired. The steel has, in particular, a similar hardness.

[0047] Preferably, prior to the filling phase, the mold 5 and the circulation rail 1 are preheated so as to optimize the formation of the molten zone when pouring the liquid metal.

[0048] After cooling and hardening of the poured metal, the mold 5 is removed from the running rail 1 as shown in Figure 10 . The recess 4 thus filled was replaced by a new ZN zone containing the cooled liquid metal. In other words, the circulation rail 1 has a “dressing” made from the poured metal.

[0049] Preferably, the repair method comprises a finishing step in which the outer contour of the traffic rail 1 is restored precisely, in particular by sanding said new ZN zone. Such a finishing step makes it possible to avoid any joint defect by smoothing the profile of the traffic rail 1.

[0050] By means of the method according to the invention, it is not necessary to cut a longitudinal portion of the running rail 1 to remove a damaged area, which makes it possible to avoid the formation of weld joints in a running rail 1, in particular a very long LRS rail. A very long damaged area located deep in the running rail 1 can be repaired conveniently and quickly. In addition, the formation of an “oblong” notch makes it possible to form a fusion zone of sufficient thickness to form a robust weld compared to a “rectangular” notch.

[0051] Such a repair process can be implemented in situ on the railway track, which reduces repair time and costs. Thanks to the repair process, damaged areas of different natures, sizes and types can be advantageously repaired.

Claims

1. A method for repairing a railway circulation rail (1), said circulation rail (1) extending longitudinally along an axis (X) vertically along an axis (Z), said circulation rail (1) including an upper part (11), adapted to be in contact with a wheel of a railway vehicle, which includes at least one damaged zone (ZE), the method including: - a step of withdrawing the damaged zone (ZE) so as to form a recess (4) in the upper part (11) of the circulation rail (1), said recess (4) having, in a longitudinal section plane (X, Z), a concave profile (40) successively including a first curvilinear portion (41), a longitudinal portion (42) and a second curvilinear portion (43), characterised in that the method further includes the following steps: - a step of placing a mould (5) about the recess (4), and - a step of filling the mould (5) with liquid metal (6) so as to fill said recess (4) and thus repair said circulation rail (1), the step of withdrawing the damaged zone (ZE) including at least one step of withdrawing by means of a template by oxygen cutting.

2. The method according to claim 1, wherein the recess (4) has a depth (P1) configured to preserve a residual thickness of the upper part (11) of the circulation rail (1) between 6 and 10mm.

3. The method according to one of the preceding claims, wherein the recess (4) has a total length (L1) between 126 and 140mm, preferably, in the order of 130mm.

4. The method according to one of the preceding claims, wherein the length (L2) of the longitudinal portion (42) of the recess (4) is between 50 and 80mm.

5. The method according to one of the preceding claims, wherein the radius of curvature of each curvilinear portion (41, 43) of the recess (4) is between 40 and 44mm, preferably, in the order of 42mm.

6. The method according to one of the preceding claims, wherein at least one curvilinear portion (41, 43) is an arc-of-circle portion with a constant radius of curvature.

7. The method according to one of the preceding claims, wherein the step of withdrawing the damaged zone (ZE) includes at least the three following phases: - a first phase of withdrawing by means of a first template (61) allowing a circular cutting the radius of curvature (R3) of which corresponds to that of the first curvilinear portion (41), - a second phase of withdrawing by means of a second template (62) allowing a circular cutting the radius of curvature (R4) of which corresponds to that of the second curvilinear portion (43), and - a third phase of withdrawing so as to form the longitudinal portion (42) of the profile of the recess (4).

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