FIELD OF INVENTION

The present invention relates to a metal rails repair mold, particularly railway rails.

It also relates to a method for repairing a rail that makes use of such a mold.

BACKGROUND OF THE INVENTION

Throughout this application, we will use the term "pad" to refer to the lower part of the rail which is based on a cross, while they respectively designate by "mushroom" and "soul", the path bearing and the vertical orientation thread which connects the pad to the fungus. This definition applies to all types of shoes, whether in profile "Vignola" or otherwise.

The focus here especially to the rails, the upper part of the fungus is degraded.

This degradation is often the result of wear of the rail or rolling incidents, so that the road surface is not uniform but rather presents surface irregularities that may compromise security.

In such situations, it is known to intervene on site to cut the portion of rail affected by degradation, replace it with a "rail coupon", that is, a new rail section and weld it coupon existing rail.

It is easily understood that such an operation is expensive, tedious and time-consuming. Even if it is justified when the degradation is very important, it has no real purpose when the fault has a limited scope in terms of depth and length.

However, since it is proposed to fix the rail by a thermite weld, we may face the following challenges.

A known on-site response procedure that uses a mold made entirely of sand. The mold is placed on either side

a region of the rail to which the fault has been removed, and the molten steel obtained by aluminothermic reaction is poured into the mold so as to fill the recess created by the absence of withdrawal.

I t is usually necessary to break the sand mold against the mold to adjust the better the contact surfaces in order to ensure sealing vis-à-vis the molten metal to be poured into the mold, which is a condition for success of repair. This is tedious and not always provides a perfect seal.

Furthermore, we can not exclude that the defect to be repaired is located in an area wherein, at the time of laying of the railway line, two rail sections have been welded to each other by an electrical welding ( " flash butt welding 'according to English terminology) which generates extra thicknesses which can reach up to three millimeters. Of course, the beads and other traces of solder present on the fungus were carefully removed by grinding in particular. This is not however the case in other parts of the track that are not running surfaces.

The beads resulting from the present electric welds other than on the fungus could be ground before repairing the rail. But this is difficult to envisage practical because the operators have less time for repair, the road to be closed to traffic during the shortest period possible. However, such a grinding operation should be conducted carefully so as to ensure a perfectly tight contact surface between the rail and the mold.

Under these conditions, it is understandable that these surface irregularities pose sealing problems since it is proposed to repair a damaged rail, thermite welding in a mold which encloses both sides the whole rail in the damaged area.

The present invention is precisely to fill this gap.

SUMMARY OF THE INVENTION

Thus, in a first aspect, the present invention relates to a welding mold thermite of a metal rail which has at least two substantially identical parts or shells configured to be temporarily mounted facing one another and on either side of said rail to clamp the fungus, and core pad of said rail, each part or shell having an upper opening which opens on an inner cavity

delimited by walls configured for clamping the fungus, the core and the pad of said rail, characterized in that said internal cavity comprises a compressible coating of sealing only against the wall configured to enclose said core, skate and below the fungus and excluding the rest of the fungus and below the pad.

According to one embodiment said coating is felt réfractai re.

According to one embodiment, the thickness of said coating is between 2 and 10 mm.

Particularly advantageously, the bottom of the opposite part to the cavity has a bevel cut configured to avoid contact with a fastening system of the rail-tie.

A second aspect of the invention relates to a method of repairing a rail which has a surface defect at its mushroom, characterized in that it comprises the following steps of:

- removing said defect so as to create a recess on the rail head of said rail;

- position the two parts or shells of a mold as described above on either side of said rail;

- filling said recess in said casting mold, said upper opening, a thermite weld material.

According to one embodiment, the present core, substantially at right defect to be repaired, a weld bead resulting from an electric welding and the compressible coating of the mold is closely applied on said bead.

BRIEF DESCRIPTION OF DRAWINGS

Other features and advantages of the invention will become apparent from reading the following description of a preferred embodiment of the invention. This description is made with reference to the accompanying drawings in which:

- Figure 1 is a very simplified side view of a rail section having a surface defect at its bearing portion (fungus), and a surface trace of welding at its core; - Figure 2 is a perspective view of the portion of the rail of Figure 1 having a surface defect, after removal of a portion of material which embraces this defect;

- Figure 3 is a view similar to Figure 2, the removed portion of material, however, having a different shape;

- Figure 4 is a figure similar to Figure 1 showing the rail after repair;

- Figures 5 and 6 are perspective views, in two different directions, of a portion of a mold according to the present invention;

- Figures 7 and 8 are perspective views of a rail section to be repaired, shown in relation to a mold part according to the invention, said section being visible in Figure 7 by transparency.

DETAILED DESCRIPTION OF THE INVENTION

In Figure 1 is schematically shown a metal rail section of railway.

Well known per se, this rail comprises a poppet 10, a core 11 and a pad 12. It has been referenced 2 a surface defect presented by the poppet 10 at its upper rolling surface. This default instance occupies an area of a few cm 2 .

Substantially at right of the defect 2 extends at the level of the core 11, a bead 110 of welding resulting from an electric welding. This bead form an irregularity on the surface of the core 11.

This is typically the kind of track that is proposed to repair using the mold of the invention.

To Figures 2 and 3 is shown a smaller part of the same rail, represented as one proceeded prior to removal of the surface defect 2, so that there is the presence of a recess 3 in the surface of the head 10.

The shape of the recess 3 is based on the technique that has been used for the removal operation. Thus, in Figure 2, the removed area has straight edges and perpendicular in pairs, obtained by grinding the rail, whereas in Figure 3, the recess has a bottom curve obtained by oxy-cutting. This shape has no influence on the characteristics of the mold and the method according to the present invention. Naturally, the skilled artisan can choose any other defect removal technique suitable surface without departing from the scope of the present invention.

In Figure 4 is shown which is, in some way, the object of the present invention, namely a fixed rail 1 having a void filler 30, instead of the recess 3 of Figures 2 and 3.

Referring now more specifically to Figures 5 and 6 to describe the mold according to the invention.

This mold consists of two pieces (or shells) 4 substantially identical, and preferably exclusively formed of sand. We will not go in detail on how to make such a mold, as it is known in itself and not the heart of the invention.

For clarity, only one piece 4 has been represented here. It is laterally delimited by two parallel faces 40 and 41. It has in its upper part a front face 42 which is divided into two portions disposed on either side of an opening 43 which connects the upper part of the mold with the cavity less than 44 molding it presents.

The lower part of the mold is divided into two regions: the molding cavity 44 intended to be arranged around the head of the rail which is delimited by a wall 45, and a bearing surface against the web and the rail foot, formed by walls 46, 48.

The wall 45 is configured to grip the mushroom 10 of the rail 1, while the wall 46 is intended to grip the core 11 and the wall 48 is intended to grip the pad 12 of the rail. The wall 45 includes a portion 451 which is intended to be in contact with the underside of the fungus.

According to the invention, the lower mold part comprises a compressible coating sealing 5 only against the walls 451, 46 and 48 configured to grip said core, skate and below the mushroom, and excluding the rest of the fungus and underneath the pad.

According to an advantageous embodiment, this coating is made of refractory felt. It is made integral with the walls by means of an adhesive. The coating thickness is typically between 2 and 10 mm.

According to an advantageous embodiment, the lower part of the workpiece 4 opposite to the cavity 44 has a diagonal cut 47 more pronounced than on conventional thermite welding molds to allow to place the mold at any location of the rail. Indeed, if the service is performed in line with an electric welding positioned on a cross member, fastening systems (bolts, tie screws, etc.) protrude above the rail foot. To prevent the pieces of the mold coming into contact therewith (making it impossible the implementation of the mold), said bias section 47 is designed to allow to place the mold on any fastening system.

Referring to Figures 7 and 8, it is easily understood how positioning of the two portions 4 of the mold M, on either side of the rail 1, so that the opening 43 is located vertically above the recess 3.

When this positioning is performed and which have been implemented all preparatory operations such as operation, is performed the casting of a thermite material to fill the recess 3.

Because the compressible coating lies opposite regions may have surface irregularities such as electric welding bead, the material deforms and intimately applied against these irregularities. In doing so, there is no risk that the molten material from flowing outside in the region concerned, ie that of the recess.

CLAIMS

1. A mold (M) aluminothermic welding of a metal rail (1) which comprises at least two parts or shells (4) substantially identical, configured to be temporarily mounted opposite one another and on either side of said rail (1) to clamp the head (10), core (11) and shoe (12) of this rail (1), each part or shell (4) having an upper opening (43) which opens on an internal cavity (44) bounded by walls configured (45, 46, 48) to clamp the head (10), the core (11) and the shoe (12) of said rail (1), characterized in that said internal cavity (44) comprises a compressible sealing coating (5) only against the walls (451, 46, 48) configured to grip said core (11), shoe (12) and below the head (10), and to 'except the rest of the poppet (10) and the underside of the shoe (12).

2. A mold (M) according to Claim 1, characterized in that said coating (5) is refractory felt.

3. A mold (M) according to one of claims 1 or 2, characterized in that said coating (5) is between 2 and 10 mm.

4. A mold (M) according to one of claims 1 to 3, characterized in that the lower part of the coin (4) opposite the cavity (44) has an oblique section (47) configured to prevent contact with a fastening system of the rail-tie.

5. A method of repairing a rail (1) having a surface defect (2) at its head (10), characterized in that it comprises the following steps of:

- removing said defect (2) so as to create a recess (3) on the head (10) of said rail (1);

- position the two parts or shells (4) of a mold (M) according to one of claims 1 to 4 on both sides of this rail (1);

- filling said recess (3) by pouring in said mold (M), by said upper opening (43), a thermite weld material.

6. A method according to claim 5, characterized in that the core (1 1) has, substantially at right defect (2) to be repaired, a bead (1 10) of welding resulting from an electric welding and the compressible coating (5) is closely applied on said bead.