WO1999020840A1

WO1999020840A1 - Rail for railway line with reinforced railhead

Info

Publication number: WO1999020840A1
Application number: PCT/FR1998/002201
Authority: WO
Inventors: Jean-Luc Perrin
Original assignee: Sogerail
Priority date: 1997-10-20
Filing date: 1998-10-14
Publication date: 1999-04-29
Also published as: FR2769928B1; AU9545498A; FR2769928A1; ZA989444B; AR015974A1; EG21994A

Abstract

The invention concerns a rail, preferably a flanged rail comprising, cast integral by reduction rolling of a semi-finished product coated on its face designed to form the flange (8) with a coat of material for reinforcement against wear, a coating made of said material continuously covering at least the active surface (7) of the railhead (3) rolling surface (6) and rail shoulder (13), and preferably also the fillet (16) connecting the outer flank (10) of the flange (8) with the edge strip (11). Such a rail is preferably used for constructing railway lines for urban transport vehicles such as tramways or light rail rapid transit, for reducing wear and noise pollution.

Description

REINFORCED MUSHROOM RAIL

The present invention, relating to the field of transport, relates to a railway rail, more particularly a grooved rail. The grooved rails of the type under consideration are rails intended to be buried and the use of which is carried out essentially in an urban environment to provide support and guidance for city rail vehicles, such as the tramway or light metropolitan trains.

It will be recalled that the head of a grooved rail of the type of the invention comprises a tread table intended to support the vehicle on wheels, and which adjoins a guide groove receiving the flange of the wheel, this groove being bordered by a bib which serves as a lateral slide in curves and which prevents the throat from being buried by the ground.

We know that the use in urban areas of buried rails poses in a particularly increased way two problems, which exist in general in rail transport: the problem of noise and that of rail wear, which moreover can be itself even the cause of noise pollution.

The noise problem affects aspects related to the comfort of local residents and for which partial responses have already been attempted, or are to be deepened, in particular in terms of anti-noise or anti-creak coating of surfaces in mutual contact during driving.

That of rail wear is much more technical, because it irreparably leads to the decommissioning of the transmission line if appropriate answers are not provided. As we have been able to show, we can distinguish two types of wear:

"wear on curves" caused on the edges of the groove by the lateral thrust of the wheel flanges in tight curves and which can, in extreme conditions, cause derailments, and so-called "striated" wear, including the exact mechanisms of training are still only partially elucidated. The phenomenon of wear by streaks, which mainly characterizes frequent stop-start journeys specific to urban transport, mainly affects the tread in contact with the wheel treads. It can be the cause of damage to vehicle chassis, as well as the source of noise caused by wheel vibrations. As described for example in GB n ° 591 8 (AD 1 91 1), the usual solution consists in removing material on new rail by surface machining, at the level of the most vulnerable regions which are the top of the rolling table at the point of contact with the tire as well as the rolling leave of the mushroom, namely, in the particular case of grooved rails, the connecting leave of the groove with the rolling table on one side and of the flap on the other. Then, a sacrificial reloading of these areas is carried out by welding with a reinforcement material, therefore more resistant than the steel of the rail (conventionally an alloy of Cr-Ni with Mo). A resumption of rectification is then necessary to find the nominal profile of the rail before setting it into track. During use, the rail is regularly recharged and rectified at these locations to compensate for the loss of the reinforcing material due to wear due to friction.

The advantage of the method is that it is not necessary to remove the buried rail to recondition it. However, its cost is obviously very high, even prohibitive. In addition, there is inevitably created a thermally affected zone (ZAC) suitable for any welding, which requires a final reheating in an attempt to restore the mechanical properties, which are in any case difficult to achieve due to the relatively high carbon content. steel from which the rails are usually made. In addition, welding-heating inevitably creates thermal deformations which, given the rather complex geometrical shape of the groove rail head, are difficult to recover even by a new rail straightening operation.

The object of the present invention is to provide an answer to the problem of the wear of the rails, in particular grooved rails, which overcomes the disadvantages of the aforementioned known remedies

To this end, the subject of the invention is a railway rail, the head of which is reinforced against wear and which is characterized in that, in order to reinforce the head, the rail is obtained directly from rolling, according to the usual process of rolling railway tracks, of a metallurgical semi-finished product, advantageously constituted by a bloom resulting from continuous casting, having a face filled with a reinforcing material at least over part of its width, said face being that intended for forming the mushroom during rolling, and in that it comprises, in the laminated state, a continuous layer formed by said reinforcing material which extends over the entire length of the rail and completely covers the width of the working table as well as its working leave. Preferably, the object of the invention is a grooved rail intended to be buried and used in an urban environment for the transport and guidance of railway vehicles, such as light railways and metropolitan trains, and whose reinforced mushroom against wear comprises a tread, a side flap and, between the two, a guide groove having the edge of its flanks formed by connecting leaves with the tread (the rolling leave), on the one hand and, on the other hand, with the side flap, this grooved rail being characterized in that, in order to reinforce the mushroom, the rail is obtained directly by rolling, according to the usual process of rolling the grooved rails, of a semi-finished product metallurgical, advantageously a bloom from continuous casting and having a face filled with a reinforcing material at least over part of its width, said face being that intended for splitting during rolling. e for making the groove, and in that it comprises, in the laminated state, a continuous layer formed by said reinforcing material which extends over the entire length of the rail and completely covers the width of the table turnover as well as the rotation leave.

Preferably, the connecting fillet of the groove with the lateral flap is also coated with a continuous layer of said reinforcing material.

More preferably, the reinforcing coating layer has a thickness which decreases from the rolling leave. As we understand, the solution. proposed by the invention consists in making the rail reinforced directly by rolling. A ready-to-use rail is thus obtained by rolling with the reinforcing materials where it is needed, with the right profile and the right straightness without requiring rework, and without zone affected by heat (ZAC) since the reheating before rolling. erases on the coated semi-finished product to be laminated the ZAC possibly created when the reinforcement material is added. Similar techniques have already been reported for the installation of an anticorrosion coating for rails of railway lines that are not very used (for example: FR 2 697 452).

The invention thus also relates to a method of manufacturing such a railroad, according to which the rail is rolled from a metallurgical semi-finished product of rectangular steel section for rail, characterized in that l '' is applied to one side of the semi-finished product, a layer of reinforcing material which completely covers it, then laminates said semi-finished product in the usual way of rolling a grooved rail, but performing the mushroom forming operation on the coated face.

Preferably, the naked semi-finished product is a bloom resulting from continuous casting.

The application of the layer of reinforcing material on one face of the bare semi-finished product can be done in various ways, for example by hot-filling of a molten filler metal, by welding a strip, by co -lamination of the semi-finished product and of such a strip, or by any other known or future technique allowing the production of a composite semi-finished product, formed by the superposition of a steel bloom for rail with a surface layer single-sided material resistant to wear by friction, such as an alloy of Ni-Cr-Mo for example, and which is already known and used for the same purposes. The invention will be well understood and other aspects and advantages will appear more clearly in the light of the description which follows, given by way of nonlimiting example, with reference to the accompanying sheet of drawings in which:

- Figure 1 shows, seen in cross section, a finished grooved rail ready for use according to the invention;

- Figure 2 is a block diagram showing the steps in a method of manufacturing a grooved rail according to the invention.

In Figure 1, we recognize the profile of a grooved rail with its shoe 1, its vertical core 2 which ends in a mushroom 3. This mushroom constitutes the active part of the rail, since it is intended to come into contact with the wheels of the railway vehicle (not shown) placed above, once the railway line constructed from a parallel double row of rails according to FIG. 1 placed end to end. Such a railway line is conventionally buried in soil 4 up to a level 5 leaving the fungus 3 flush.

This mushroom is itself conventionally formed of three functional parts, juxtaposed from left to right in the figure: the tread table 6 first, the top 7 of which constitutes the active surface of the rail in contact with the wheels of the support vehicle, the groove 8 next, intended to receive the wheel flange to guide it in curves by coming into abutment against its sidewalls 9 and 10, and finally the flap 1 1 serving as lateral anti-derailment slide by its internal blank 10 as well as a partition preventing the burial of the groove 8. The mushroom 3, the core 2 and the shoe 1 are usually obtained in one piece by rolling a steel bloom for rails from a continuous casting machine producing blooms or slabs to be split into blooms. As can be seen, the tread table is coated with a layer

1 2, coming from rolling of the rail, in material resistant to wear by friction, such as an alloy based on Nickel-Chromium, doped with Molybdenum, or such as an austenitic steel. The thickness of the layer 1 2 is preferably at least 2 mm at the most stressed place that is the rolling leave 13 connecting the inner blank 9 of the groove 8 with the top of the rolling table 6.

This layer can be of constant thickness over the entire table 6. It can also preferably be reduced progressively from the fillet 13 on either side of it, to the outer edge 14 of the table and along the flank 9 of the throat. In any case, it must imperatively be continuous, therefore without uncovered zones, even local ones, over the entire width of the active surface 7 of the fungus and extend towards the bottom of the groove on the inner flank 9 thereof covering the leave of rolling 13. Preferably, as can be seen in FIG. 1, the flank 10 of the groove formed on the flap 1 1 can also have its top edge covered by a layer 1 5 of reinforcement material with constant or progressive thickness from of the connection leave 1 6 between the groove and the flap. We will see with reference to FIG. 2 how the layers 1 2 and 1 5 come jointly from the same initial layer on the semi-finished product to be laminated, from which they come directly from rolling, while the bottom 17 of the groove is found, him, bare of any reinforcement coating, which turns out to be an economic advantage by saving material since an anti-wear reinforcement at this location would be useless.

Referring now precisely to Figure 2, one can chronologically follow the main stages of manufacturing the process of a rail according to the invention.

A bloom 20, made of usual steel for rail tracks, comes from a continuous casting installation 21 and directed into a coating station 22 so as to be covered on one side by a layer 23 of an anti-reinforcing material. wear (Ni-Cr alloy, doped with Mo, for example). After reheating in an oven 24 to bring it to its rolling temperature, the semi-finished product 20-23, coming from station 22, is rolled in a rolling train 25 of the usual type for the manufacture of grooved rails. The grooved rail 26 obtained is then brought to ambient temperature by staying in a cooler 27, before being cold dressed in a straightening machine 28 which ensures the straightness of the product. The latter then undergoes quality control in an inspection unit 29 before finishing its manufacturing process in a finishing station 30, where it is in particular cut to length and perforated in the places provided for then mounting it on the track. It will be noted that the rolling train 25 is a train entirely in accordance with those conventionally used or usable for the rolling of grooved rails, namely a train whose successive cages are provided with grooved cylinders, which gradually print on the blank passing through the cages, the desired final profile in shape and dimensions.

However, care will be taken to orient the coated bloom 20-23 at the entrance to the train 25 so that the throat formation operation, known as the "splitting operation") which is carried out by depressing a face of the roughing by rolling rolls provided with a rib for this purpose, is carried out well on the face of the semi-finished product filled with the reinforcing layer 23.

This filling is carried out, as has been said, in the coating station 22. Different application techniques are possible, such as explosion, co-lamination of a filler strip with the bare bloom to be coated , metallization by projection on the face to be coated, reloading of this face by arc welding of flats or wires of reinforcing material placed one next to the other according to the width of the face to be filled. Any metal coating technique may be suitable in this regard if it allows, as already mentioned, to coat with a continuous layer 23 the entire face of the semi-finished product to be laminated, or only part of its width.

By way of tests, which proved to be conclusive, this coating was carried out by hot reloading using austenitic steel wires deposited and arc welded until forming by spreading the material a constant layer. filling the entire affected side of the bloom to be laminated.

It is useful to emphasize, at this stage of the presentation, the two essential aspects underlying the industrial feasibility of a coated mushroom-grooved rail according to the invention: the effect of "front splitting" for the formation of the groove, and the possibility of having an initial coating layer 23 continues on the semi-finished product to be laminated, which is of variable thickness depending on the width of the face to be filled.

We were able to discover in fact that it is the "splitting" operation itself which naturally made it possible to separate the initial layer 23 into two continuous zones each, but separated on the finished product, one 1 2 covering the table bearing 6 and the bearing leave 1 3, the other 1 5 covering the connection leave 1 6 of the flap 1 1, and at the same time creating a groove bottom 1 7 free of any coating (which would be there superfluous), whereas this place, on which the rib of the rolling rolls is positioned, was however initially lined.

In addition, we have been able to show that this place on the face coated with the semi-finished product to be laminated, not only had to be filled to ensure the desired end result mentioned above, but filled with a layer thickness preferably higher there than elsewhere. . One could thus by this only particularity obtain on finished rail a thickness of layer of reinforcing more important on the leaves 1 3 and 1 6 (the most requested by the wear in curve) and going gradually decreasing when one moves away of these leaves. In other words, it will be advantageous to retain a technique of metallic coating, current or to come which, like that already mentioned with reloading by welding of wires or flats, makes it possible to achieve initial layer thicknesses 23 variable on the width of the face to be trimmed. It goes without saying that the invention is not limited to the embodiment described above, but extends to multiple variants or equivalents insofar as its definition given by the claims which follow is respected.

In particular, the covering layer 23 may relate to only part of the face to be trimmed so that only the active surface 7 of the finished rail is reinforced. Here too, the technique by reloading by welding appears to be well suited.

Likewise, many alloys may be suitable for constituting the reinforcing material. Preferably, austenic steels, or ferrous alloys, or not, having, by weight, at least 10% of Cr or Ni or Mn, or a combination of the three reaching at least these 10% by weight, and Mo in a quantity by weight of 3% at most, or conventionally between 0.5% and 1%. Likewise, by "a reinforcing layer" is meant at least one layer, it being understood that it would indeed be perfectly feasible to coat the face concerned with the semi-finished product to be laminated by several superimposed layers of different materials, or by a single layer but with a gradient of properties depending on its thickness.

It will also be recalled that, although the invention was originally conceived for grooved rails, it nonetheless remains applicable also to the "T" rails of conventional railways, the head of which is only formed by a tread table. bordered on each side by a rolling fillet and on one or the other of which rubs the wheel flange in the curves, depending on whether the curve turns right or left.

In addition to the top of the tread table which will be reinforced, the reinforcing layer will then preferably cover the two leaves so that the rail can be placed either on the left line or the right line when it is being laid. However, it can be limited to covering only one leave, if the symmetry of the geometric shape of the rail makes it possible to reverse its direction of deposition on the track.

Claims

1) Railway rail, the mushroom of which is reinforced against wear, characterized in that, in order to reinforce the mushroom, the rail is obtained, according to the usual rolling process of railway rails, directly by rolling a metallurgical semi-finished product (20) having a face filled with a reinforcing material (23) at least over part of its width, said face being that intended for forming the mushroom (3) during rolling, and that said semi-finished product comprises, in the laminated state, a continuous layer (12) formed by said reinforcing material (22) which extends over the entire length of the rail and completely covers the width of the tread table ( 6), as well as his rollover leave (9).

2) Rail according to claim 1, of the "grooved rail" type intended to be buried for use in an urban environment for the support and guidance of railway vehicles such as light metropolitan trams, and the reinforced head of which comprises a tread, a side flap and, between the two, a guide groove having the edge of its flanks formed by connecting leaves with the tread on the one hand (the rolling leave), and, on the other hand, with the side flap, grooved rail, characterized in that, in order to reinforce the mushroom (3), the rail is obtained directly by rolling, according to the usual process of rolling the grooved rails, by a half product (20) having a face filled with a reinforcing material (23) at least over part of its width, said face being that intended, during rolling, for splitting to produce the groove (8) of the raii, and in what it entails, to the laminated state, a continuous layer (12) formed by said reinforcing material and which extends over the entire length of the rail, completely covering the width of the active surface (7) of the tread table (6), as well as the turnover leave (9).

3) Grooved rail according to claim 2, characterized in that the side flap (1 1) is also coated with a continuous layer (15) of reinforcing material on the connecting fillet (16) with the outer flank (10) throat (8). 4) Grooved rail according to claim 2 or 3, characterized in that the coating (12, 15) has a thickness at least equal to 2 mm at the connection fillets (13, 16).

5) Rail according to claim 1 or 4, characterized in that the tread (6) has a layer (12) of reinforcing material whose thickness is decreasing from the rolling leave (13, 14)).

6) Rail according to claim 1 or 2, characterized in that the reinforcing material constituting the coating comprises at least 10

% by weight of one or more elements chosen from Cr, Ni and Mn, and at most about 3% of Mo.

7) Rail according to claim 1 or 2, characterized in that the semi-finished product (20) from which it is derived is a bloom obtained by continuous casting.

8) A method of manufacturing a railway rail according to claim 1 or 2, according to which the rail is laminated from a semi-metallurgical product of rectangular section, characterized in that it is deposited on one side of the semi-finished product to be laminated (20) a layer (23) of reinforcing coating which covers at least partially said face and in a continuous manner, then the semi-finished product thus coated is laminated in the usual way of rolling track rails iron, but by performing the mushroom forming operation on said coated face.

9) Method according to claim 8, characterized in that is deposited on one side of the semi-finished product (20) a layer (23) of coating of variable thickness depending on the width of the face.

10) Method according to claim 8, characterized in that one carries out the deposition of the layer (23) on one side of the semi-finished product (20) by co-rolling a strip and the semi-finished product (20) , or by reloading by welding wires or flats on said face.