Method for rehabilitating rail fixing blades known as “Nabla®” and device for rehabilitating said blades

Abstract

Method for the rehabilitation of rail fixing blades known as “Nabla®”, comprising the following steps: (a) selection of the Nabla® blades from a set of railway parts, (b) identification of the unbroken blades and selection of these blades, (c) control of the thickness and the curve of the blades, (d) determination of the stiffness of the blades; (e) detection of cracks in the blades; (f) restoration of the blades selected at the end of steps a) to e) with a view to their reuse. Installation for implementing the method

Description

Title of the invention: Method for rehabilitating rail fixing blades known as “Nabla®” and device for rehabilitating said blades Technical field

[0001] The invention relates to the technical field of rail fastening parts, used in the railway industry. More particularly, the invention relates to a so-called "Nabla®" rail fastening blade, constituting the Nabla® elastic rail fastening system.

[0002] In the context of the invention, the terms “rail fixing blade”, “Nabla blade” and “Nabla toad” are synonymous and can be used interchangeably. Prior art

[0003] The Nabla® fastening system is one of the most widely used rail fastening systems in France. It allows the rail to be fixed to a sleeper. In practice, this system comprises a plastic stop, a rail base and a Nabla® blade, fixed together using an anchoring system, generally consisting of a lag screw and an insulating sheath. The blades are made of metal, particularly spring steel, and can withstand a significant clamping force.

[0004] Today, fastening systems are replaced every 30 years. After that, the used blades are discarded and discarded. However, as part of a sustainable economy, there is a general need to reuse used products. Applied to the field of the invention, it would be necessary to develop a process for rehabilitating used Nabla® blades.

[0005] The NF F 50-015 standard establishes the physical, mechanical and geometric characteristics that Nabla® blades must meet in order to be used on tracks.

[0006] These characteristics are listed exhaustively below: surface presenting no external defects (fold, crack, lack of material), geometry having to present the dimensions as defined in the standard, resistance to salt spray, resistance to fatigue, high elasticity with a specific stiffness, specific hardness, resistance to tightening.

[0007] To the applicant's knowledge, there is no method for measuring the capacity of a Nabla® blade to be reused on the tracks despite its theoretical end of life, a period of approximately 30 years.

[0008] In other words, the problem that the invention sets out to solve is that of developing a process for rehabilitating used Nabla® blades. Statement of the invention

[0009] The Applicant has developed a process for rehabilitating blades, after having identified the major criteria that Nabla® blades must meet in order to, if not comply, at least come as close as possible to the NF F 50-015 standard.

[0010] These include: the general appearance of the blade (absence of breaks or cracks in the blade), the geometry of the blade and the stiffness of the blades.

[0011] The invention also consists of having developed means for measuring these criteria.

[0012] In other words, the invention consists of a method for rehabilitating Nabla® blades, comprising several control steps making it possible to determine whether the blades comply with at least 3 geometric, physical and mechanical requirements described in standard NF F 50-015 with a view to being reused in a rail attachment system.

[0013] More specifically, the present invention relates to a method for rehabilitating used rail fixing blades known as “Nabla®”, comprising the following steps, which are advantageously successive: (a) selection of Nabla® blades from a set of railway parts, (b) identification of unbroken blades and selection of these blades; (c) control of the thickness and curve of the blades; (d) determination of the stiffness of the blades; (e) detection of cracks in the blades; (f) restoration of the blades selected at the end of steps a) to e) with a view to their reuse.

[0014] In a particular embodiment, steps a) and b) are carried out successively and before the rest of the steps while the order of carrying out steps c), d) and e) is interchangeable and the latter systematically precede step f).

[0015] Preferably, steps a) and b) of selecting the parts and identifying the unbroken parts are carried out using artificial intelligence. This selects only the Nabla® blades and excludes other railway parts, for example the Nabla® griffon type fasteners.

[0016] In addition, artificial intelligence identifies the appearance of the blades and selects only those that are not broken.

[0017] The artificial intelligence was trained on a sample of around a hundred parts to identify Nabla® blades from other types of fasteners and to recognize unbroken parts. During this training, each part was classified as "compliant" or "non-compliant" to establish a reference model. Thus, the artificial intelligence only selects blades similar to this model.

[0018] For example, blades broken in two, with missing parts or with significant cracks are considered non-compliant and are discarded.

[0019] The blades not presenting these defects are selected and are subjected to control of thickness and curve of the blades.

[0020] For each blade, the thickness and curve control includes the following steps: - modeling of the profile of a used blade by laser scanning; - comparison of the digital profile obtained from the used blade with the profile of a reference blade conforming to standard NF F 50-015, - selection of blades whose numerical profile and thickness are substantially identical to those of the reference blade.

[0021] Preferably, at least five points on the blade are scanned using a laser scanner. At each point, the geometry of the blade is determined on both sides of the blade. This makes it possible to model the blade curve and determine its thickness. From these measurements, software creates a digital profile of the blade.

[0022] This profile is superimposed with the profile of a reference blade and the software calculates the differences in shape and thickness between the digital profiles of the two blades.

[0023] In practice, the geometry of the reference blade is fixed from the measurements defined in the NF F 50-015 standard. Thus, by comparing the curve and thickness of the used blades with those of the reference blade, it is possible to determine whether the used blades have the regulatory dimensions.

[0024] Thus, only the blades having a profile similar to that of the reference blades and a conforming thickness are kept, while the others are discarded.

[0025] The selected blades are subjected to the stiffness determination step.

[0026] Preferably, the determination of the stiffness of the blades is carried out according to the following steps: - progressive application of a force of 25 kN on a blade, - measurement of the deformation at a point on the blade, - selection of blades whose deformation curve is included in the taper of the clamping force-deformation curve as defined by standard NF F 50-015.

[0027] The protocol for determining the stiffness of the blades is described in standard NF F 50-015 in the “tightening force-deformation curve” section.

[0028] In practice, the blades are placed on a rigid assembly, reproducing the normal geometric positioning of the fastener. A load of 25 kN is applied in steps of 2.5 kN and the deformation is measured at a precise point of the fastener at each step.

[0029] The displacement values ​​of the point as a function of the applied force are plotted on a graph, including a spindle as defined by standard NF F 50-015. Only the blades having a curve included in the spindle are kept, then subjected to the crack detection step.

[0030] In principle, the detection of cracks in blades comprises the following steps: - making an impact at the end of one of the faces of a blade; - laser vibrometer measurement of vibrations generated by impact, to identify the presence of cracks.

[0031] A laser vibrometer is used to capture vibration measurements generated by an impact. It generally consists of a laser source and an interferometer. The vibration spectrum obtained is compared to a reference spectrum, measured on a new blade. In general, cracked parts include peaks not present in the spectrum of the new part. Similarly, some peaks in the spectrum of the new blade do not appear in the spectra of the cracked parts.

[0032] Only parts that do not contain any cracks are selected.

[0033] In a particular embodiment, the restoration of the blades comprises cleaning, stripping and applying a coating to the blades. Once stripping is completed, the corrosion protection coating is applied.

[0034] According to one embodiment of the invention, the blades are subjected to marking between step e) and step f). This makes it possible to ensure unit traceability.

[0035] Another object of the invention relates to a Nabla® blade rehabilitation installation comprising: - a means of selecting Nabla® blades from a set of railway parts, - a means of identifying unbroken blades, - a carousel including: - a unit for controlling the thickness and curve of the blades, - a unit for determining the stiffness of the blades, - a unit for detecting cracks in the blades, - a storage unit for selected blades, and - a storage unit for unselected blades.

[0036] Advantageously, the means for selecting Nabla® blades and the means for identifying unbroken blades are each artificial intelligence.

[0037] According to a characteristic of the invention, the thickness and curve control unit comprises a laser scanner, which makes it possible to digitize the profile of the blades and to measure their thickness.

[0038] According to another characteristic of the invention, the blade stiffness control unit comprises a compression machine, a stiffness test bench and a position sensor. The compression machine is, for example, an electric jack.

[0039] Preferably, the blade crack detection unit comprises a laser vibrometer.

[0040] According to one embodiment of the invention, the installation further comprises a blade marking unit. Brief description of the drawings

[0041] [Fig.l] is a diagram of a Nabla® attachment system.

[0042] [Fig.2] is a photo of a Nabla® blade showing the area in which the thickness and curve are determined according to a particular embodiment of the invention.

[0043] [Fig.3] is a diagram of a Nabla® blade rehabilitation installation.

[0044] [Fig.4] is a graph representing the spindle of the stress-strain curve according to the technical specification CT IGEV 533A which supplements the NF 50-015 standard. Detailed description of the drawings

[0045] Referring to [Fig.l], the Nabla® attachment system 1 comprises a Nabla® blade 2a, a stop 2b, and a lag screw 2c for fixing a rail 4 to a sleeper 3.

[0046] Referring to [Fig.2], the Nabla® 5 blade is in a trapezoidal shape, comprising a small base 6, a large base 7 and an opening 8. The large base 7 measures 160 mm, the small base 6.73 mm and the opening 8 has a diameter of 28 mm. The height of the blade 5 is approximately 120 mm. The blade 5 has a zone 9 located between the opening 8 and the large base 7, the width of which, measured between the center of the opening 8 and the center of the large base 7, is 50 mm. The thickness and curve of the blade 5 are controlled at this zone 9, as will be detailed later.

[0047] Referring to [Fig. 3], the Nabla® blade rehabilitation installation 10 comprises an automated rotating carousel 11 comprising four working units arranged in a circle.

[0048] In practice, used railway parts are transported to a sorting line 12. An artificial intelligence 13 selects the Nabla® blades 13 and identifies those which are not broken. A loading gripper robot 14 then places the selected blades one by one at the entrance to the carousel 11.

[0049] Each blade passes through a stiffness determination unit 15. They are first arranged in a suitable manner on a stiffness test bench located under an electric jack. A compressive force of 25 kN is gradually applied, and the displacement of a characteristic point, called H, located in zone 9 of the blade (with reference to [Fig.2]), approximately 5 mm from the center of the large base 7, using a position sensor. The curve of the point displacement (mm) is plotted as a function of the applied compressive force (kN). The blades with a curve included in the spindle as shown in [Fig.4] are transferred to the blade thickness and curve control unit 16. Non-compliant blades are sent to the blade discharge conveyor 19, after having gone around the carousel. They will be transferred to a storage unit for unselected blades (not shown).

[0050] Subsequently, each blade passes through a unit 16 for controlling the thickness and curve of the blades. This includes a laser scanner which digitally reconstructs a profile of the geometry of each blade and measures the thickness. For this, a sampling of five points is used, measured on both faces of the blade and located in zone 9 of the blade, with reference to [Fig.2]. In total, ten measurements are taken. The profile of the part is superimposed on that of the reference part and software measures their deviations. Parts with a non-compliant profile and a significant deficit in thickness remain on the carousel but will be directed at the end to the storage unit for unselected blades.

[0051] At the crack detection unit 17, the analyzed blade is placed on rubber pads, in order to isolate the blade from ambient vibrations. An impact is made at one end of zone 9 of the blade (with reference to [Fig.2]) and the vibrations of the part are measured using a laser vibrometer. The vibration frequency spectrum obtained is compared to a reference spectrum at specific frequencies. This comparison makes it possible to identify the presence of a crack with the appearance or disappearance of characteristic peaks.

[0052] The blades free of cracks and having been selected following the checks carried out are engraved by a marking unit 18.

[0053] Subsequently, they are unloaded from the carousel 11 using the unloading gripping robot 20 and sent to the blade evacuation conveyor 19 to be stored in the storage units for selected or non-selected blades, then packaged.

[0054] Finally, the selected blades are cleaned, stripped and a corrosion protection coating is applied to the blades so that they can be reused on the railways.

Claims

Claims

1. 1. Method for rehabilitating used rail fixing blades known as “Nabla”, comprising the following steps: (a) selection of Nabla® blades from a set of railway parts, (b) identification of unbroken blades and selection of these blades; (c) control of the thickness and curve of the blades; (d) determination of the stiffness of the blades; (e) detection of cracks in the blades; (f) restoration of the blades selected at the end of steps a) to e) with a view to their reuse.

2. 2. Method according to claim 1, characterized in that steps a) and b) are carried out using artificial intelligence.

3. 3. Method according to claim 2, characterized in that the control of the thickness and the curve of the blades comprises the following steps: - modeling the profile of a used blade by laser scanning; - comparison of the digital profile obtained from the used blade with the profile of a reference blade conforming to standard NF F 50-015; - selection of the blades whose digital profile and thickness are substantially identical to those of the reference blade.

4. 4. Method according to one of claims 1 to 3, characterized in that the determination of the stiffness of the blades is carried out according to the following steps: - progressive application of a force of 25 kN on a blade, - measurement of the deformation at a point of the blade, - selection of the blades whose deformation curve is included in the taper of the force-deformation curve as defined by standard NF F 50-015.

5. 5. Method according to any one of claims 1 to 4, characterized in that the detection of cracks in the blades comprises the following steps: - carrying out an impact at the end of one of the faces of a blade; - measuring by laser vibrometer the vibrations generated by the impact, to identify the presence of cracks, - selecting the blades not showing cracks.

6. 6. A method according to any one of claims 1 to 5, characterized in that the restoration of the blades comprises cleaning, stripping and applying a coating to the blades.

7. 7. Method according to any one of claims 1 to 6, characterized in that the blades are subjected to marking between step e) and step f).

8. 8. Nabla® blade rehabilitation installation, implementing the method according to one of claims 1 to 7, comprising: - a means for selecting Nabla® blades from a set of railway parts, - a means for identifying unbroken blades, - a carousel comprising: - a unit for controlling the thickness and curve of the blades, - a unit for determining the stiffness of the blades, - a unit for detecting cracks in the blades, - a unit for storing selected blades, and - a unit for storing unselected blades.

9. 9. Installation according to claim 8, characterized in that the means for selecting the Nabla blades and the means for identifying the unbroken blades are each an artificial intelligence.

10. 10. Installation according to claim 8 or 9, characterized in that the unit for controlling the thickness and curve of the blades comprises a laser scanner.

11. 11. Installation according to any one of claims 8 to 10, characterized in that the unit for determining the stiffness of the blades comprises a compression machine, a stiffness test bench and a position sensor.

12. 12. Installation according to any one of claims 8 to 11, characterized in that the unit for detecting cracks in the blades comprises a laser vibrometer.

13. 13. Installation according to any one of claims 8 to 12, characterized in that the installation further comprises a blade marking unit.

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