Bonded electrically insulated joint system for railway rails, method for fabricating such, method of modifying at least one starting type switch rail and use of two switch rails modified in accordance with said modifying method

Abstract

A bonded, electrically insulated rail joint (IRJ) assembly for railways or subways is realized by machining two standard switch rails and subsequently coupling them by use of a lower bolted cover plate.

Claims

1. A bonded insulated rail joint (IRJ) system comprising: a first switch rail (1); a second switch rail (2); wherein both said first and said second switch rails (1, 2) have a first portion (1; 2) of predetermined longitudinal length with a standard rail structure that connects to a second portion, lowered with respect to the first portion, said second portion comprising, at one of its sides, a conjugate coupling surface (S) and having, on an opposite side, a portion of a switch blade structure; and wherein said conjugate coupling surfaces (S) are such that, when said first and said second switch rails are coupled together by said two conjugate coupling surfaces (S) placed in contact with each other, the structure of a switch blade or rail is restored in a coupling section, said switch blade or rail having a foot, a web and a head; and further comprising a bolted cover plate (8) forming a second foot, to which at least part of said foot of the switch blade or of the rail restored as a result of said coupling is fixed.

2. The bonded insulated rail joint system, according to claim 1, wherein, following their coupling, said conjugate coupling surfaces (S) generate a transition line (L) which forms, for at least a section of its length or for several sections of its entire length or for its entire length, a predetermined angle with respect to a longitudinal axis of the switch rail on which said transition line is provided.

3. The bonded insulated rail joint system, according to claim 1, wherein said first and second switch rails (1, 2) are of standard type and said conjugate coupling surface (S) is a surface obtained by choice of: chip removal of said second portion of a starting standard switch rail; forging said second portion of the starting standard switch rail; or a combination of both of the preceding options.

4. The bonded insulated rail joint system, according to claim 1, further comprising a first layer of electrically insulating material (15) inserted between the conjugate coupling surfaces (S) which couple together, and a second layer (11, 11) of the electrically insulating material inserted between the bolted cover plate and said second foot which connects to the bolted cover plate.

5. The bonded insulated rail joint system, according to claim 1, further comprising first connecting means (3, 4, 5, 6, F) for connecting said first switch rail with said second switch rail through said conjugate coupling surfaces.

6. The bonded insulated rail joint system, according to claim 1, further comprising second connecting means for connecting said second portions to each other coupled to said plate (8).

7. The bonded insulated rail joint system, according to claim 6, wherein said second connecting means further comprise one or more blocking elements (10, 10) shaped so as to overlap for a part thereof with the foot of the rail restored by the coupling of said conjugate coupling surfaces (S) and, for another part thereof, abutting plate (8) so as to be fixed to said cover plate by bolts or screws.

8. The bonded insulated rail joint system, according to claim 1, wherein said first and said second switch rails comprising said conjugate coupling surfaces (S) are arbitrary and mutually identical.

9. The bonded insulated rail joint system, according to claim 1, wherein said conjugate coupling surface (S) extends longitudinally for a predetermined length so as to form, following coupling, a transition (L) having a longitudinal length extending further for a full height of said second portion.

10. A method for fabricating a bonded, electrically insulated rail joint (IRJ) assembly comprising: providing a first starting standard type switch rail (1) having a first portion (1) of a predetermined longitudinal length with a standard rail structure that connects to a subsequent second blade portion that is asymmetrical and lowered with respect to the first portion; providing a second starting standard type switch blade bar (2) having a first (2) portion of a predetermined longitudinal length with the standard rail structure that connects to a subsequent second blade portion that is asymmetrical and lowered with respect to the first portion; machining at least part of said second portion for both said first and second starting switch rails in such a way as to modify said second portion by obtaining on one side of said second portion a conjugate coupling surface (S) and maintaining an original structure on an opposite side; jointing of said first and second switch rails together by bringing said two conjugate coupling surfaces (S) into contact with each other in such a way as to restore, following coupling, a structure of a switch blade or rail, said switch blade or rail having a foot, a web and a head; and fastening the foot relative to the said restored switch blade or restored rail with a bolted cover plate (8) arranged underneath said foot.

11. The method, according to claim 10, wherein said machining is: a machining operation on machine tools for chip removal; machining by forging; or a combination of both.

12. The method, according to claim 10, wherein, as a result of coupling said two conjugate coupling surfaces (S), a transition line (L) is generated which forms, for at least a section of its length or for several sections of its entire length or for its entire length, a predetermined angle with respect to a longitudinal axis of the switch rails on which said transition line is provided.

13. The method, according to claim 12, wherein the jointing of said first and said second switch rails is performed by drilling the two conjugate coupling surfaces with one or more holes passing transversely through an entire thickness and applying first connecting means.

14. The method, according to claim 10, wherein said coupling conjugate surface (S) extends longitudinally for a predetermined length so as to form, following the coupling, a transition of a longitudinal length extending over an entire height of said second portion from the head to the foot of said second portion.

15. The method according to claim 10, wherein the jointing provides a joint that is electrically insulated and bonded at least by insertion of a layer of electrically insulating material and assisted with adhesive material at least between the two conjugate coupling surfaces (S) and between the foot and the bolted cover plate.

16. A method of modifying a starting standard type switch rail (1) having a first portion (1) of predetermined longitudinal length with a standard rail structure which connects to a subsequent second portion asymmetrical and lowered with respect to said first portion, said method comprising: machining at least one portion of said second portion of said starting switch rail in such a manner as to modify a side of said at least one portion of said second portion by obtaining on said side a conjugate coupling surface (S) and maintaining an original structure on an opposite side.

17. The method according to claim 16, further comprising a step of coupling said first portion and said second portion together by bringing the conjugate coupling surfaces (S) into contact with each other to form a bonded insulated rail joint (IRJ) assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0121] The invention, in one or more of its embodiments, will be detailed below in accordance with the following drawings:

[0122] FIGS. 1A, 1B, 1C, 2, 3 and 4 show solutions in the known art, described above;

[0123] FIG. 5 shows, in order to appreciate the differences in web thickness, the cross-section of a standard rail and the cross-section of a switch rail; The Figure shows the nomenclature normally used in the technical field and highlights how the web of a switch rail is thicker than the web of the standard rail;

[0124] FIG. 6 shows in isometric views the solution indicated here as heavy and therefore preferable in case of high external and thermal loads; In FIG. 6 the very low angle of inclination of the coupled surfaces with respect to the rail axis (indicated as the longitudinal axis) through the machining and coupling of two standard forged switch rails (bars) may be appreciated; In particular, the Figure highlights precisely the small angle formed between the longitudinal axis and the L line joining the two parts;

[0125] FIG. 7 shows isometric views of the adopted solution;

[0126] FIG. 8 shows an exploded view of the adopted solution in which all its components are visible;

[0127] FIG. 9 shows a cross-section at an end nail;

[0128] FIG. 10 shows an isometric view of a track in the section where the IRJs are provided developed according to the heavy solution adopted, which allows to appreciate how it is compatible with ordinary couplings and sleepers, without requiring any modification to the current track;

[0129] FIG. 11 shows a light version, therefore suitable for lower thermal and mechanical loads and therefore preferable for applications such as subways where thermal expansion is lower, for example;

[0130] FIG. 12 shows variants in which the coupling surface formed on the side of the switch blade portion is not necessarily flat but can also have other profiles.

DETAILED DESCRIPTION OF SOME INVENTION CONFIGURATIONS

[0131] In accordance with the invention, the proposed solution sees, in fact, the use of the well-known railway switch (turnout) rails however used following their structural modification, to create bonded and electrically insulated rail junction systems (or simply joint as the case may be) to replace those currently known.

[0132] Thus, in an advantageous embodiment of the invention, the solution comprises the arrangement of at least two switch rails which are machined (e.g. milled and/or forged) according to a sloped direction with respect to the longitudinal direction of the switch rails so as to obtain in each switch rail a conjugate coupling surface (S) (also referred to for simplicity in the remainder of this description as coupling surface) which allows the two switch rails to be coupled together, thereby restoring following coupling, a blade or rail structure with a head on which the convoy wheel can normally roll. The foot of the restored blade is fixed to an underlying plate (a bolted cover plate).

[0133] It is well known that switch rails, with a low, asymmetrical cross-section, are partially forged to take the shape of a normal rail at one end, so that they can be jointed to the remaining parts of the track.

[0134] More specifically, it is known that the switch rail is obtained from a rail of a predetermined length whose cross-section, with reference to FIG. 5, corresponds entirely to the one on the left indicated as switch rail section.

[0135] It is lower than the standard height of a normal rail as well as asymmetrical while the head, which forms the convoy wheel running surface, is the same in both the switch blade and the normal rail.

[0136] In a switch rail production process, starting from a long bar with a section like the one in FIG. 5 on the left switch rail section, a forging step is carried out on an end portion of the bar in order to shape it like a standard rail and thus according to the sectional shape in FIG. 5 on the right standard rail section.

[0137] This provides a transition from the low, asymmetrical, switch blade shape to the standard rail to be jointed with the rest of the rails.

[0138] The standard rail structure is easily achieved by heating this portion in an induction furnace to bring the material to a plastic state and deforming it through passages in special die presses (thus performing a forging process). Through such passes in moulds, the end of the bar takes on the desired normal rail shape (i.e., higher than the remaining blade section and with a thinner web). This means the modified end part is used to create the junction of the switch rail to the normal rail.

[0139] That being said, as introduced above, the present invention sees the use of the well-known switch rail which, however, in its non-forged part (i.e., the lowered asymmetrical part) is instead machined and/or forged.

[0140] In fact, the use of two forged standard switch rails with a 60E1A2 section and suitably shaped (see European standard EN 13674-2), each with a web thickness (d) of 40 mm, makes it possible to achieve a total web of no less than 54 mm after coupling (as better described below), compared to a web thickness (d1) of 16.5 mm of a standard 60E1 rail (see European standard EN 13674-1).

[0141] These switch rail web dimensions allow for an extremely small angle of less than 3 and a correspondingly large coupling length of more than 500 mm.

[0142] This implies, as further explained below and with reference to FIG. 6, that the angle formed by the longitudinal axis of the IRJ obtained from the two coupled switch blades and the cut-off line L, which represents the coupling line, is an angle that may be equal to or even less than 3.

[0143] The thickness of the web therefore allows cuts that extend for a good length (l), therefore equal to or even greater than 500 mm, as shown for clarification (but not limitation) in FIG. 6, without risking weakening and the creation of sharp bodies.

[0144] The length of the coupling is limited by the need to fit the proposed solution into a current track without any constraints on the type of couplings and spacing of the sleepers.

[0145] More specifically, therefore, the concept of the invention consists mainly in exploiting the standard switch rail, in particular the un-forged part (with reference to FIG. 5 the left-hand side switch rail section) to carry out a machining process which can be, for example, on machine tools, by forging or by other equivalent systems, in order to obtain, on one side of the switch blade, a coupling surface S (also called in the present description face S or flat surface S in an equivalent manner) which couples with a twin.

[0146] The side opposite the S-coupling surface is not machined but is instead retained in its original structure.

[0147] In this way, the coupling restores the switch blade or rail shape.

[0148] The fact that the switch blade is lowered, in accordance with the proposed solution, also allows for a lower counter plate, which makes the entire system structurally stable.

[0149] Briefly, the invention, which shows in FIG. 6 a heavy solution with preferably five holes as an example only, consists in using standard switch rails (1, 2), forged as customary, as starting elements for the subsequent switch blade creation to obtain the standard rail shape.

[0150] More specifically, as is evident from FIG. 6, a coupling line (L) can be seen which presents a small angle to the switch blade longitudinal axis.

[0151] FIG. 8 in fact shows the two separate switch blades in an exploded view and shows that at their end, which is not forged, these switch blades are machined on one side so as to obtain a coupling surface (S).

[0152] The two switch blades are machined in such a way as to obtain mirror-image twins which, when coupled, restore the original head of a rail (which is equivalent (said head) in size and structure to that of an original switch blade).

[0153] The machining, in fact, affects one side in order to generate the coupling surface S (see also FIG. 12, for example) while the opposing side remains unchanged (i.e., is not modified).

[0154] Thus, the coupling of said two portions regenerates a rail or switch blade structure in which, in addition to the foot and web, the head on which the convoy wheel rolls is provided.

[0155] The above-mentioned machining is carried out on two switch rails, which are not only a standard component but also a component with a web of increased thickness compared to a standard rail (please note here, with reference to FIG. 5, that a switch rail web has a thickness of 40 mm compared to 16.5 mm for the standard rail). This allows the realisation of a coupling surface S that follows a development direction at a small angle to the longitudinal direction (even less than 3), without the inconveniences that were experienced in the known art when working on a standard rail, thus with too small a web thickness.

[0156] The coupling of the two parts, as then shown in a section of FIG. 9, restores an original head size and with a web section that can even be much higher than the known art solutions.

[0157] The coupling surfaces (S) affect one side of the switch blade, for a certain length and small slope in relation to the longitudinal axis of the switch blade being machined.

[0158] This coupling surface (S) also extends across the full height of the switch blade in its un-forged part, from the foot to the head, therefore removing material from the foot to the head or, in case of forging, flattening and modifying the shape from the foot to the head as can be seen clearly from both FIG. 8 and FIG. 9.

[0159] In a possible variant of the invention, then, the coupling surface (S) can easily be obtained by material removal on machine tools, e.g., by milling.

[0160] For example, two switch blades can be placed side by side as shown in FIG. 8 on a milling cutter table and held in position on a work base, e.g., by means of a magnetic system that holds the two switch blades in position.

[0161] The two switch blades, placed next to each other at a certain distance, rest with their foot on the magnetic base and are therefore held in place by the magnetic force. This keeps the area subject to material removal free with a firm hold.

[0162] The milling cutter, preferably of the numerically controlled type, lowers itself and rotating at a certain speed removes material, thus creating the two surfaces (S) in the two switch blades. The two switch blades will be practically twins (therefore identical), so that by inverting one of them relative to the other (i.e., one rotated 180 relative to the other with rotation on an axis orthogonal to the plane of support) the two machined parts can couple to produce the structure of FIG. 9 or FIG. 6 or 7.

[0163] It is worth noting here that the creation of surface (S) can also be achieved by a method similar to that already in use for the creation of the standard switch rail, i.e., by forging.

[0164] In particular, the unforged end section of the switch blade (i.e., for clarity, the left-hand section in FIG. 5 switch rail section, which in accordance with the first configuration is machined by milling) can also be forged to yield the desired final shape, i.e., surface (S).

[0165] According to this variant, therefore, starting from a switch rail with one forged and one unforged part, the unforged part is now forged. This involves a process in which the part to be modified is heated to a temperature that brings the metal to a condition where it can be machined by plastic deformation and then said deformation is performed using, for example, die presses with one or more passes.

[0166] In all of the above cases, a surface (S) is obtained like the one in FIG. 8 or FIG. 12 whose line of development in the longitudinal direction (i.e., along the longitudinal length) forms a certain angle to the longitudinal direction of the switch blade.

[0167] The length along the direction of longitudinal development of the surface S, as mentioned, can even exceed 500 mm, and this processing affects the entire height from the foot to the head.

[0168] When the twin parts are thus coupled (see, for example, FIG. 6), the joint line (L) has a certain angle to the longitudinal direction of development, the angle being, however, small. This angle can advantageously be less than 4.5 degrees, for example, preferably less than or equal to 3.

[0169] However, those skilled in the art will be able to assess the most suitable angles according to his or her needs.

[0170] Going further into the structural description of the invention, switch rails (1, 2) are preferably coupled by means of screws or nails (3, 7), (see e.g., FIG. 6), although other mechanical connection systems are not excluded.

[0171] The coupling, therefore, requires through holes (F) in the surfaces (S), as shown by the exploded view in FIG. 8. Holes F are transverse holes that from surface S pass through the entire thickness of the remaining web.

[0172] In this regard, in order to produce holes that will be precisely aligned with each other, it is preferable to work on switch rails already machined and coupled with each other.

[0173] In this way, it is possible to cancel errors resulting from tolerances otherwise present in the standard solution in which switch rails are machined separately.

[0174] Once the two surfaces (S) have been realised, the two switch blades thus modified are preferably coupled, bringing the two surfaces (S) into alignment as shown in FIG. 6 for example, and drilling is carried out on axis, which then allows the connection systems to be inserted.

[0175] This also makes it possible to drill small-diameter holes that cause less weakening of the section and allow the use of thinner insulators. The number and size of nails, screws or other connection systems can be optimised according to the loads to be transmitted; for example, up to at least six of the usual 25.4 mm diameter nails can be used.

[0176] Of course, a drilling solution without necessarily coupling the two switch blades together is not excluded.

[0177] Since the height of the 60E1A2 switch rail is 134 mm compared to 172 mm for a 60E1 rail (see also FIG. 5), this difference in height (38 mm) is advantageously exploited by implementing a bolted cover plate 8 with a high coupling surface, which contributes significantly to both the structural strength and the vertical flexural rigidity of the IRJ, the latter being much more uniform than in traditional IRJs.

[0178] FIG. 5, for the sake of clarity, shows with delta of height the difference in height between the forged portion of the right standard rail and the left switch rail showing precisely how the section of the un-forged switch blade is lowered compared to the forged portion.

[0179] This difference in height (delta of height which is approximately 38 mm as mentioned) is used to install, as clearly shown in FIG. 9, the bolted cover plate, which is nothing more than a plate, preferably metal, with flat surfaces on which the foot resulting from the coupling of the two surfaces (S) abuts and is fixed. FIG. 9, reproduced below, clearly shows a cross-section of the coupling between bolted cover plate 8 and the two switch blades machined as described and placed on the bolted cover plate.

[0180] The bolted cover plate 8 can be secured with normal screws 12, bolts in general or similar.

[0181] Screws or bolts generally penetrate through the cover plate and intercept the foot, completing the connection.

[0182] If necessary, additional elements (10, 10, 11, 11, 14) cooperating with the screws or bolts in general may be provided.

[0183] For example, FIG. 8 shows in the exploded view that screws 12 penetrate through blocks (10, 10) that overlie the foot.

[0184] More specifically, a larger detail is shown by the exploded view in FIG. 8 in which, assuming that all connections are obtained with the help of the usual high-strength adhesives, all the elements required to realise the proposed solution are observed:

[0185] First of all, switch rail 1 with profile 60E1A2 is highlighted, which is commercially available with a forged transition 1 and ending with a rail profile (1) 60E1 also concurrently obtained by forging. The originally unforged portion involves processing to create the above-described sloped surface (S), which can be obtained, as mentioned, by machining (on machine tools, e.g., with a milling machine) or by forging.

[0186] Holes (F) on the web (in particular through-holes through the surface (S)) for subsequent assembly are highlighted.

[0187] FIG. 8 also shows an additional hole (F) for connection to the bolted cover plate (8).

[0188] FIG. 8 shows, of course, an entirely identical second switch rail 2 (i.e., the twin) for which what has already been described applies;

[0189] A template 15 is then provided made of electrically insulating material, preferably GRP, shaped to mimic surface (S) and with holes matching holes (F).

[0190] Given the particular length and smoothness of the coupling that develops longitudinally (preferably for more than 500 mm), which drastically reduce shocks and the associated plastic deformations of the rail head, said template can be made particularly thin compared to conventional IRJ head templates, virtually eliminating surface damage to the rails and guaranteeing a particularly durable geometry.

[0191] FIG. 8 then shows irreversible locking nails 3, including steel shimming washers 4 and insulators 6.

[0192] Locking collar 7 and insulating sleeve 5, which are used to lock the elements (1, 2, 15) just described together, are then highlighted.

[0193] Again, the exploded view in FIG. 8 shows bolted cover plate 8, which is provided with suitably machined surfaces (8) to allow easy mounting on standard cross beams and with a series of threaded holes required for subsequent locking.

[0194] Also shown is a corresponding insulating template 9 which is intended to isolate bolted cover plate 8 from switch rails (1, 2).

[0195] One or more screws 12, including steel shimming washers (12) and insulating washers (12) are additionally fitted with an insulating sleeve 13. They are designed to connect switch rails (1, 2) with bolted cover plate (8) with insulating template (9) therebetween.

[0196] A number of additional elements may further be provided, specific to heavy solutions, also referred to in this description as sleepers (10, 10). They are provided with appropriate insulating templates (11, 11) and further bind, by means of screws 14, bolted cover plate 8 with switch rails (1, 2) while maintaining the electrical insulation. Preferably, so called sleepers can be implemented in those joints that are particularly mechanically stressed.

[0197] FIG. 9 allows viewing the insulating elements between nail and switch rails 5, between lock washers and switch rail 6, between sleepers and switch rails and between bolted cover plate 8 and bars 9. Of particular interest is the fact that both insulators 15 and 5 can be manufactured in much smaller thicknesses than standard solutions, the former due to the softness in the wheel-rail contact that avoids plasticisation and the latter due to the possible simultaneous machining of the bars.

[0198] They can therefore be fabricated below the aforementioned 5 mm thickness of known art, so having thicknesses in the order of 1.5 mm, for example.

[0199] The light solution, shown as an example with only three nails in FIG. 11, is essentially identical to the previous one but is obtained by eliminating the cross-pieces and simplifying the bolted cover plate. This results in a version optimised for rigid rails, low loads, low temperature ranges, and small rail cross-sections.

[0200] With reference to the coupling surface obtained in the switch blade portion, as mentioned above, this is preferably flat as the flat shape is obviously the easiest to fabricate.

[0201] However, as also sketched in FIG. 12, nothing precludes that the coupling surface be conveniently fabricated in any shape (obviously either by forging or milling).

[0202] By way of example, therefore, four possible variants of the coupling surface are shown in FIG. 12, from right to left: [0203] A flat surface; [0204] A surface fabricated with a split profile (preferably with 10 mm fittings); [0205] A surface fabricated with a split profile (preferably with 40 mm fittings); [0206] A surface fabricated of circular areas (preferably 500 mm in radius);

[0207] It can be seen that in the last three conditions, a self-centring shape coupling (so-called

[0208] positive) is advantageously obtained, which locks the IRJ by binding its surfaces mechanically and not by friction, greatly increasing the resistance of the IRJ.

[0209] It can also be seen that while in the flat solution transition (L) is obviously a straight line in the last three conditions of the cases in FIG. 12 (i.e., broken profile or with circular arcs), transition sections are determined.

[0210] Each transition section preferably has small angles, i.e., angles that are preferably less than or equal to 10 and even more preferably less than or equal to 3.