阅读说明：本技术 用于铝热焊接轨道的模制组件以及用于铝热焊接轨道的方法 (Molded assembly for thermite welded rail and method for thermite welded rail ) 是由 尼古拉斯·德蒙 克莱芒·梅雷斯 蒂亚戈·桑托斯 于 2018-10-08 设计创作，主要内容包括：本发明涉及一种用于金属轨道(30)的铝热焊接的模制组件,所述模制组件包括至少一个模具部件(1,50),所述至少一个模具部件被构造成与至少一个其它模具部件(1,50)以及待焊接的轨道(30)接触,以便形成模具腔体(102),待焊接的金属轨道的端部(31)布置在所述模具腔体中,并且熔融金属被浇铸到所述模具腔体中以便焊接所述金属轨道(30),所述模制组件表征为,每个模具部件(1,50)包括支撑表面(13),所述支撑表面构造为被放置成与所述轨道(30)中的至少一个接触,所述支撑表面(13)包括凹槽(60),由膨胀材料制成的密封产品(40)被施加到所述凹槽中。(The invention relates to a molded assembly for thermite welding of a metal rail (30), comprising at least one mold part (1, 50), the at least one mould part being configured to be in contact with at least one other mould part (1, 50) and a rail (30) to be welded, so as to form a mould cavity (102) in which an end (31) of a metal track to be welded is arranged, and molten metal is poured into the mould cavity for welding the metal track (30), the moulding assembly being characterized in that each mould part (1, 50) comprises a support surface (13), the support surface is configured to be placed in contact with at least one of the rails (30), the support surface (13) comprises a groove (60) into which a sealing product (40) made of an intumescent material is applied.)

1. A moulding assembly for thermite welding of a metal track (30), said moulding assembly comprising at least one mould part (1, 50), the at least one mould part being configured to be in contact with at least one other mould part (1, 50) and a rail (30) to be welded, so as to form a mould cavity (102) in which an end (31) of a metal track to be welded is arranged, and molten metal is poured into the mould cavity for welding the metal track (30), the moulding assembly being characterized in that each mould part (1, 50) comprises a seat (13), the seat is configured to be placed in contact with at least one of the rails (30), the seat (13) comprises a groove (60) into which a sealing product (40) made of an intumescent material is applied.

2. Moulding assembly according to claim 1, wherein the groove (60) comprises:

-an inner edge (11) configured to close the mould cavity (102);

-an outer edge (61) configured to separate the groove (60) from the outside of the mould;

-a bottom extending facing a rail (30) to be welded and connecting the inner edge (11) with the outer edge (61).

3. Moulding assembly according to any of claims 1 or 2, wherein the sealing product (40) is recessed with respect to the seat (13) with respect to the rail (30).

4. Moulding assembly according to any of the preceding claims, wherein the mould part (1, 50) comprises a bottom part (50).

5. Moulding assembly according to any of the preceding claims, wherein the sealing product (40) is in the form of a strip (41).

6. Moulding assembly according to claim 5, wherein the strip is a thermoformed strip or a strip obtained by moulding.

7. The molding assembly of any of claims 5 or 6, wherein the strip is conformable to the mold member.

8. The moulding assembly according to any of the preceding claims, wherein the expanding material is selected from one or more of the following chemicals: sodium silicate, calcium silicate, ammonium phosphate and co-extruded graphite.

9. A method for thermite welding of a metal rail (30), wherein an end (31) of the metal rail to be welded is arranged in a mould cavity (102) of a thermite welding mould (100), the mould (100) comprising at least two mould parts (1, 50) configured to be in contact with each other and with a rail (30) to be welded so as to form the mould cavity (102), each mould part (1, 50) comprising a seat (13) configured to be placed in contact with at least one of the rails (30), the seat (13) comprising a groove (60), the method comprising the step of casting molten metal into the mould cavity (102), the method is characterized in that it comprises a step of applying a sealing product (40) made of an intumescent material into the groove (60) before the step of casting metal into the mould cavity (102).

10. The method of claim 9, comprising the step of preheating the mold (100) prior to the step of casting metal into the mold cavity (102), the sealed product (40) being applied prior to the preheating step.

11. The method of claim 9, wherein the sealed product (40) is applied before assembling the components (1, 50) of the mold with the rail (30) to form the mold cavity (102).

12. Method according to claim 9, wherein the sealing product (40) is applied so as to be recessed with respect to the seat (13) with respect to the rail (30).

13. A method according to any one of claims 9 to 12, wherein the sealed product (40) is in the form of a strip (41), the method comprising the step of shaping the strip (41) before it is applied on the mould parts (1, 50).

14. The method according to claim 13, wherein the strip is a thermoformed strip or a strip obtained by moulding.

15. The method of any one of claims 13 or 14, wherein the strip conforms to the mold component during application of the strip.

16. Method according to any one of claims 9 to 12, wherein the sealing product (40) is in the form of a liquid, preferably selected from an adhesive or a sealant.

17. The method according to claim 16, further comprising the step of applying the liquid on the at least one surface (21, 22) of the mould part (1, 50) facing the rail (30) before casting the molten metal into the mould cavity (102).

18. The method of claim 17, wherein the applying of the liquid is performed by means of a brush, a knife, a squeeze gun, or a high pressure piston.

19. The method of any one of claims 9 to 18, wherein the intumescent material comprises sodium silicate.

Technical Field

The present invention relates to a moulded assembly for thermite welding and a method for implementing such a moulded assembly for thermite welding of metal sections, in particular rails.

Prior Art

Thermite welding of two metal sections consists of: aligning the two metal sections so that their ends face each other; molten metal is then cast into the spaces separating the ends to weld the segments.

For performing the welding, a mould is used comprising a plurality of parts closing the metal sections, so as to form a mould cavity which accommodates the ends of the metal sections to be welded and is intended to receive the molten metal.

This type of welding is usually carried out for the welding of metal rails, in particular railway rails.

Due to the structure of the parts of the mould, and the dimensional differences existing between the metal track to be welded and the mould, the coupling between the parts of the mould on the one hand and the coupling between the parts of the mould and the metal track on the other hand is not perfect, and therefore the mould must be closed before casting the metal.

This operation (known as "sealing") is usually performed by applying a paste or sealant, sand or, alternatively, an adhesive applied by a squeeze gun, into the gap to be filled, before or after placing the mould in place around the metal track to be welded. These sealing products have refractory properties, that is to say they are able to withstand contact with the molten metal when it is cast into the mould cavity and generally give good sealing results.

However, applying these sealing products is lengthy and laborious, since they need to be deposited with great precision to ensure optimal tightness of the mould. This also creates additional financial costs for performing the welding due to the purchase and transport of the sealed product (sometimes representing up to several kilograms per weld).

Furthermore, the sealed product generates a certain amount of waste which must be removed and disposed of, which has a negative impact on the environment.

Disclosure of Invention

The object of the present invention is therefore to overcome the drawbacks of the prior art by proposing a molding assembly comprising a mold for thermite welding of metal rails, the sealing of which is easy and quick to perform.

It is also an object of the invention to propose such a molding assembly, the sealing of the mold of which is carried out with reduced financial costs and results in a reduced amount of waste compared to the molds of the prior art.

Another object of the invention is to propose a method for thermite welding of metal rails implementing such a moulded assembly.

To this end, the invention relates to a molding assembly for thermite welding of metal rails, comprising at least one mold part configured to be in contact with at least one other mold part and a rail to be welded, so as to form a mold cavity in which an end of the metal rail to be welded is arranged and into which molten metal is poured so as to weld the metal rail, the molding assembly being mainly characterized in that each mold part comprises a seat configured to be placed in contact with at least one of said rails, said seat comprising a groove into which a sealing product made of an intumescent material is applied.

Optionally, the moulding assembly according to the invention may comprise the following features:

the recess includes:

an inner edge configured to close the mold cavity,

an outer edge configured to separate the groove from an exterior of the mold,

a bottom which extends facing the track to be welded and which connects the inner edge with the outer edge.

The sealing product is recessed with respect to the track with respect to the seat;

the seat is provided with a compressible refractory lining, which can be brought into contact with the rail during installation of the mould, on which compressible refractory lining the sealing product is applied;

the mold part comprises a bottom part;

the sealed product is in the form of a strip;

the strip is a thermoformed strip or a strip obtained by moulding;

the strip may conform to the mold member;

the intumescent material is selected from one or more of the following chemicals: sodium silicate, calcium silicate, ammonium phosphate and co-extruded graphite (co-extruded graphite).

The invention also relates to a method for thermite welding of metal rails, wherein the ends of a metal rail to be welded are arranged in a mould cavity of a thermite welding mould, said mould comprising at least two mould parts configured to be in contact with each other and with the rail to be welded so as to form said mould cavity, each mould part comprising a seat configured to be placed in contact with at least one of said rails, said seat comprising a groove, the method comprising a step of casting molten metal into the mould cavity, the method being mainly characterized in that it comprises a step of applying a sealed product made of expanded material into the groove before the step of casting metal into the mould cavity.

Optionally, the method according to the invention may comprise the following features:

the method comprises the steps of preheating the mould prior to casting metal into the mould cavity, the sealing product being applied prior to said preheating step;

applying a sealed product prior to assembling the components of the mold with the rail to form the mold cavity;

the sealing product is applied recessed with respect to the seat relative to the rail;

the seat is provided with a compressible refractory lining, which can be brought into contact with the rail during installation of the mould, on which compressible refractory lining the sealing product is applied;

the sealed product is in the form of a strip, the method comprising the step of shaping the strip before it is applied to the mould parts.

The strip is a thermoformed strip or a strip obtained by moulding;

the strip conforms to the mold member during its application;

the sealing product is in the form of a liquid, preferably selected from an adhesive or a sealant;

the method further comprises the step of applying a liquid on said at least one surface of the mould part facing the rail, prior to casting said molten metal into said mould cavity;

the application of the liquid is performed by means of brushes, knives, squeeze guns or high-pressure pistons;

the intumescent material comprises sodium silicate.

Drawings

Further advantages and characteristics of the invention will become clear from the following description, given as an illustrative and non-limiting example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of components of a mold for thermite welding of metal rails according to an embodiment of the present invention;

FIG. 2 is a perspective view of the mold part shown in FIG. 1, equipped with a sealed product made of an intumescent material, the sealed product being in the form of a thermoformable strip;

FIG. 3 is a schematic view of a thermoformable strip made of an intumescent material;

FIG. 4 is a side cross-sectional view of a mold formed by assembling two components identical to the two components of FIG. 2 on each side of the ends of two rails to be welded so as to close the rail ends, according to an embodiment of the invention;

FIGS. 5A to 5C are schematic illustrations of successive steps of placing a mold part equipped with a compressible refractory lining of the felt type in position on a rail;

FIGS. 6A to 6D are schematic illustrations of successive steps of placing a mould part without a compressible refractory lining in position on a rail;

FIGS. 7A to 7D are schematic views of successive steps of placing in position a mould part without a compressible refractory lining, the seat of the mould part comprising a recess;

fig. 8A to 8D are illustrations of grooves having different shapes;

fig. 9 is a perspective view of a mold component whose seat includes a groove such as shown in fig. 7A-7D.

Detailed Description

The present invention relates firstly to a moulded assembly comprising a mould for thermite welding metal sections (and in particular metal rails).

Such a mould 100 consists of two mould parts 1, which have substantially the same structure, and a bottom part 50, one of which is shown in fig. 1 according to one embodiment. The two parts 1 are adapted to be assembled with each other and with the base part 50 in order to form a mould 100 accommodating the ends 31 of the rails 30 to be welded.

Referring to fig. 1, each mold part 1 comprises an upper face 2, a lower face 3 and lateral faces 4, 5 joining the upper face 2 and the lower face 3. The mould part 1 consists of an upper part 6 and a lower part 7, the upper part 6 being configured to be assembled to the upper part corresponding to the second mould part, the lower part 7 being configured to be in contact with the rail ends 31 in order to close them.

The mould parts 1 and 50 are made of a rigid refractory material, that is to say a material which has good mechanical strength and is able to withstand very high temperatures (and in particular the temperature of the metal to be welded in the liquid state with which it comes into contact).

The mould part 1 is hollowed out over its entire length from its upper face 2 to its lower face 3 so as to define two inner lateral surfaces 9 facing each other with respect to a longitudinal plane P1 and connected by a bottom 10. The inner lateral surface 9 is itself hollowed out so as to form, together with the bottom 10, one half of a casting chamber 101 (represented in figure 4) for the liquid weld metal, usually coming from a crucible made of refractory material arranged above the casting channel.

According to the conventional use of the mould, the directional and positioning terms such as in particular "above" and "below", "high", "low", "upper" or "lower" refer to the arrangement of the different constituent elements of the mould part or elements cooperating with the mould part, wherein the mould part is mounted on rails, the feet of which rest on a support (generally the ground) transversely to the longitudinal plane P1 of the mould part.

The front face 4 of the mould part 1 is provided with two contact surfaces 8 for contacting two corresponding contact surfaces of the second mould part 1 during mounting of the mould 100.

The lower part 7 of the mould part 1 comprises two edges 11, called inner edges, which extend from the lower end of the contact surface 8 (where they form a sloping interruption 12) to the lower end of the mould part 1. The inner edge 11 is laterally delimited by the inner lateral surface 9 and the outer lateral surface 5 of the mould part.

Each inner edge 11 comprises a seat 13 extending along said edge, configured to come into contact with the rail end 31 during mounting of the mould 100. Once the mould is assembled as represented in fig. 4, the seat 13 delimits, through the inner lateral surface 9 and the bottom 10 of the mould, a mould cavity 102 or a mould chamber which accommodates the space between the end 31 of the rail to be welded and the rail 30 and is intended to receive the liquid metal from the casting chamber 101.

The seat may be covered by felt. Felts are known per se, which consist of compressible refractory fibres and are bonded by a refractory binder, applied on the seat of the mould part by means of a suitable adhesive in order to close the mould cavity. Reference may be made to document WO 2007/031528 for describing such a mould provided with felt.

In the remainder of the description, P2 specifies a longitudinal plane of symmetry separating the rail 30 on both sides of the rail on either side of this plane over the length of the rail, the plane P2 being perpendicular to the plane P1 and transverse to the plane of the supports of the rail 30.

Each of the two seats 13 is hollowed out so as to define a high seat 14, a medium seat 15, the shape of which corresponds to the shape of one side of the head 33 of the rail 30, and a low seat 16, the shape of which corresponds to the shape of one side of the web 34 of the rail.

The upper seat 14 is in the form of a recess. It comprises a high portion 14a, shaped to correspond to the top of the head 33 of the rail 30, a middle portion 14b, shaped to correspond to the lateral edges of the head 33, and a lower portion 14c, shaped to correspond to the base of the head 33.

The middle seat 15 is in the form of a protrusion, the shape of which corresponds to the shape of the web 34 of the rail 30.

The lower seat 16 is in the form of a depression. It comprises an upper portion 16a, shaped to correspond to the top of the foot 35 of the rail 30, and a lower portion 16b, shaped to correspond to the lateral edges of the foot 35.

The inner edge 11 delimits an outer recess 20 which is located in the corresponding outer lateral surface 5 of the mould part 1 at the level of said edge 11. The outer recess 20 extends along the edge 11, that is to say from the lower end of the contact surface 8 to the lower face 3 of the mould part 1.

The outer recess 20 is itself formed by a first outer surface 21, which extends perpendicularly from the seat 13, and by a second surface 22, which extends perpendicularly from the first surface 21, and therefore substantially parallel to the seat 13.

The chamfer 23 is formed as an angle of the upper seat 14 and the surface of the upper part 6 of the coupling part. The chamfer 23 has a shape corresponding to the top of the head 33 of the rail end.

The mould part 1 further comprises a cooling pipe 24, one of the ends of which emerges on the upper face 3 of the mould part towards the outside of the mould 100 and the other end emerges in the mould cavity 102 at the level of the upper seat 14. The cut-outs are advantageously formed in the contact surface 8 and the inner lateral surface 9 and constitute a passage for the circulation of the weld metal in the liquid state between the metal casting chamber 101 and the cooling duct 24.

For mounting on the mould 100 shown in fig. 4 and performing welding of the two ends of the rail, two mould parts 1 such as previously described are assembled on the bottom part 50.

The contact surfaces 8 of the two mould parts 1 contact each other on either side of the plane P2, thereby forming a metal casting chamber 101.

For each part of the mould, the seat 13 of the lower part 7 is placed in contact with one side of the two ends 31 of the rail 30 to be welded.

In this configuration, the bottom 10 of the mould part is positioned facing the space between the two rail ends.

In detail, the first seat 13 covers a first side of the first rail end, the second seat 13 covers a first side of the second rail end in a similar way to the first seat.

For the second mould part mounted on the second side of the two rail ends, the same holds correspondingly.

When two mould parts 1 are mounted on a rail end 31 to be welded, the two seats 13 of a first mould part mounted on a first side of the rail against each of the two rail ends and the two seats of a second mould part mounted on a second side of the rail against each of the two rail ends, form a mould cavity 102 extending around the rail end 31 and the space separating the rail ends. The mould cavity 102 is preferably closed by a bottom part 50 connectable to the inner surface 3 of each mould part 1 such that the seat of said bottom part 50 is connected to the respective seats 13 of the first and second mould parts 1.

During casting of metal in liquid form into the mould 100, the metal flows along the casting chamber 101 to the mould cavity 102, where it fills the space between the ends 31 in order to weld the rails 30 by thermite reaction. The metal vapor and thermite reaction products are exhausted from the mold via cooling tubes 24.

A sealing product 40 made of an intumescent material is applied to one or both mould parts 1. It may be applied to the mold parts before their assembly on the rails to be welded, or directly to the assembled mold 100.

This material is called "expanded" in that it can be expanded under the effect of the heat brought about by the increase in temperature of the mould, in particular in the mould cavity, in order to form an expansion system, for example in the form of a foam or conversely in the form of a solid shell. In practice, the expanding material is configured to expand during the implementation of a so-called preheating step, performed before the metal is cast into the mould, which allows a gradual increase in the temperature of the mould and the rail, in order to facilitate the melting of the metal and the removal of moisture from the mould. The expansion of the expanding material is triggered when said material is subjected to a so-called "threshold temperature", which depends on its physical and chemical properties. It is therefore to be noted that the threshold temperature is made close to the preheating temperature of the mould, preferably lower than said preheating temperature.

Preferably, the intumescent material is selected from one or more of the following chemicals: sodium silicate, calcium silicate, ammonium phosphate and co-extruded graphite (co-extruded graphite).

According to a first embodiment, the sealed product 40 is in the form of a strip 41 shown in fig. 3. The strip 41 is shaped so that its shape corresponds to the shape of the surface of the mould part onto which it must subsequently be applied.

The strip 41 may be thermoformable in which it sets at an elevated temperature before it is mounted on the mould part 1 or 50, the setting temperature of the strip being a function of the physical and chemical characteristics of the intumescent material and, in practice, well below its threshold temperature.

Alternatively, the strip 41 may be molded so as to have a desired shape and then applied on a mold part.

The strip 41 may be flexible or rigid, depending on the nature of its constituent material and its dimensions. However, a flexible strip would be preferred in order to conform the strip to the mould parts.

This first embodiment offers the advantage of providing a "ready to use" sealed product, in which it is sufficient to apply the strips 41 already formed on the surface concerned, in particular by means of, for example, gluing, which is simple and quick to perform.

According to a second embodiment, the sealing product 40 is in the form of a liquid product for application on the mould parts. The term "liquid" refers to a low viscosity (e.g., a viscosity close to that of water, i.e., about 1 x 10^-3Pa.s), or a liquid of high viscosity (e.g., a viscosity close to that of engine oil, i.e., about 0.2 pa.s). However, a sufficiently high viscosity would be preferred to enable easy application of the product to the surface(s) involved, while avoiding product flow to other surfaces not arranged to have product applied thereon. It is also noted that a liquid product is selected that requires a reduced drying time compared to the drying time of the moulding operation.

The liquid product is preferably an adhesive or sealant.

This second embodiment offers the advantage of providing a sealing product 40 that can be applied on areas of complex shape, without however leaving the area to be protected uncovered with product.

The sealed product may isolate mold cavity 102 from the outside environment while preventing liquid metal from exiting the mold cavity during the molding operation.

The sealing product is positioned on at least one surface of the mould part 1 or 50 which is configured to be placed facing the rail 30 to be welded.

When the sealed product is exposed to excessive heat, particularly over a long period of time, the sealed product has a tendency to deteriorate. Therefore, the sealing product is preferably positioned at a distance from the end of the rail so that it expands during the preheating step, while avoiding that it is too exposed to heat and deteriorates. Too rapid a degradation of the physico-chemical structure of the expanded material constituting the sealed product will in fact result in a loss of the ability of the sealed product to guarantee the tightness of the mould until the solidification of the metal.

The sealing product is applied on the mould part so as to be placed in the vicinity of the mould cavity 102, and preferably outside said mould cavity. The tightness of the mould cavity 102 is thus ensured, while avoiding direct contact between the metal and the sealed product during casting of the metal into the mould 100, which may cause burrs at the level of the junction between the rail and the bearing surface of the mould against the rail.

However, it may be provided to position the sealed product at the level of the junction between the rail and the bearing surface of the mould against the rail (in particular on the seat 13, possibly covered with felt). In this case, the sealing product can enter into and come into contact with the molten metal. A sealing product is therefore selected which is able to withstand structurally contact with the molten metal.

The sealing product expands in the joint during the preheating step and then fills the joint, and then the metal enters into contact with the expanded sealing product during the molding step.

When the seat is covered by the felt, the expansion of the sealing product compresses the felt even more. This provides the following advantages: allowing the felt to compensate for shrinkage of the sealed product as it approaches the end of its life.

According to this embodiment, the structural and mechanical characteristics of the mould parts (and when they are felt present) are adapted to avoid any detachment of the seat with respect to the rail that could cause a poor tightness of the mould.

According to a preferred embodiment of the invention, with reference to fig. 2 and 3, the sealing product 40 is applied in an outer recess 20 delimited by the inner edge 11 of the mould part. Which is applied on the recessed second surface 22 so as to cover said second surface. Furthermore, it also covers at least partially the first surface 21 of the recess, depending on the thickness of the applied product. In the case where the sealed product is a thermoformable strip 41 such as represented in figure 3, the high portion 42 of the strip has a shape corresponding to the shape of the high seat 14 and is applied thereto. Similarly, the middle portion 43 and the low portion 44 of the strap 41 have a shape corresponding to the shape of the middle seat 15 and the low seat 16, respectively, and are applied thereto.

Obviously, the sealing product 40 can be applied in the outer recess 20, if necessary, so as to cover only a portion of the second surface 22, that is to say a portion of its length extending from the oblique interruption 12 to the lower face 3 of the part and/or a portion of its width extending from the first surface 21 to the outer lateral surface 5 of the mould part. This may prove suitable if the sealing product is intended to isolate only a portion of the mold cavity 102 and thus reduces the time required to apply the sealing product and the amount of product required.

During the step of preheating the mould 100, the temperature inside the mould increases up to a preheating temperature close to the temperature of the subsequently cast molten metal. The preheating temperature may in particular be equal to the temperature of the liquid metal. The increase in temperature of the mold during preheating causes an increase in temperature inside and outside of the mold cavity 102, particularly in the vicinity of the mold cavity. When the threshold temperature is reached, the sealing product 40 expands and then occupies the entire volume of the outer recess 20, preventing the metal from coming out of the mold cavity 102 via the junction between the seat 13 of the mold component and the rail 30.

What has been described previously in relation to the application of the sealing product on the surface of the mould part 1 also applies to the bottom part 50. According to what has been described, the sealing product can thus be applied, in particular, on the seat 18 of the bottom part 50, which seat 18 can comprise felt.

Fig. 5A-C and 6A-D show the behavior of the sealed product during its application on a mold part and during subsequent molding operations according to the previous embodiments. The sealing product 40 is applied in the outer recess 20 delimited by the inner edge 11 of the mould part.

Referring to fig. 5A, 5B and 5C, the mold 100 is a mold with felt. The presence of the felt 17 makes it possible to eliminate the sometimes laborious step of reducing the thickness of the inner edge 11 in order to adjust the distance between the mould part 1 and the rail 30, in particular by scraping the excess sand, when the part is made of agglomerated sand.

According to fig. 5A, a quantity of sealing product 40 is applied in the outer recess 20 before the mould is mounted. The felt 17 constitutes the edge of the mould part, the seat 13 of which is intended to come into contact with the rail 30 to be welded. The felt 17 is in a free state (not compressed) and has the reference E_F0A predetermined thickness. The seat 11 of the felt 17 and the rail-facing surface 45 of the sealing product are offset with respect to each other by a depression (denoted R)₀)。

According to fig. 5B, the mounting of the mould parts on the rails causes a compression of the felt 17, the thickness of which is reduced from E_F0To become E_F1. Recess R₀Decreases according to the compression of the felt up to a value R₁. The preheating of the mold prior to casting the metal causes expansion of the sealing product 40 which then fills the volume of the recess 20 and slightly overflows the outside of the recess as shown in fig. 5C.

In addition to preserving its structural integrity, the presence of the inner edge 11, which positions the sealing product 40 outside the mold cavity 102 and is equipped with felt that separates it from the mold cavity, makes it possible to avoid the sealing product 40 from expanding into the junction between the seat 13 and the rail 30, which could lead to the opposite effect to that expected, namely a slight detachment of the seat 13 with respect to the rail 30 and a poor tightness of the mold.

Depression R between seat 13 of felt 17 and surface 45 of the sealed product₀Is advantageously chosen so as to enable good compression of the felt. In other words, the felt 17 must be able to be compressed to the desired compression state without the sealing product 40 coming into contact with the rail 30 before expansion. When the felt 17 is compressed, the sealing product 40 is thus kept separated from the rail 30 by a recess R₁。

Continued depression R after compression of the felt₁The sealing product is allowed to expand properly into the entire volume of the recess 20 without overflowing too much outside the recess.

Referring to fig. 6A, 6B, 6C, and 6D, the mold is a mold without felt. The inner edge 11 is thus composed of the same material as the rest of the mould part 1.

According to fig. 6A, a quantity of sealing product 40 is applied in the recess 20 before the mould is mounted.

According to fig. 6B, the inner edge 11 is then shortened (for example by scraping excess sand when the part 1 is made of agglomerated sand) in order to adjust the contact between the mould part 1 and the rail 30 in a desired manner. In so doing, the thickness of the edge 11 is from E_B0Is changed into E_B1And a recess R between the seat of the edge and the rail-facing surface of the recess 20₀Down to the value R₁。

In a similar manner to the previous embodiment with felt moulds, the inner edge 11 separates the sealing product 40 from the mould cavity 102, avoiding any direct contact between the metal and the sealing product during the subsequent step of casting the metal into the mould.

Furthermore, a depression R between the seat 13 and the surface 45 of the sealed product₀Advantageously chosen so as to allow a predetermined shortening of the inner edge 11 in order to position the mould part 1 at a desired distance from the rail 30. In other words, the edge 11 must be able to be shortened as desired without the sealing product 40 coming into contact with the rail before expansion. When the edge 11 is shortened, the sealing product 40 is thus kept separated from the rail 30 by a recess R₁。

It goes without saying that the invention is not limited to the illustrated mould structure, but that it is applicable to any thermite welding mould, regardless of the number and shape of the mould parts constituting the mould. Furthermore, the expansion sealing product may be applied on all mould parts or only a part thereof.

Fig. 7A, 7B, 7C, and 7D illustrate the behavior of a sealed product such as described above during its application on a mold part and during subsequent molding operations. Unlike the previous embodiment described by the support of fig. 6A to 6D, the seat 13 comprises a groove 60 spaced from the outer part of the mould. According to the embodiment represented, the groove 60 is delimited both by the inner edge 11 and also by the outer edge 61, which is arranged in an adjacent manner and at a distance from the inner edge with respect to the length of the track and which separates said groove 60 from the outside of the mould.

According to fig. 7A, a quantity of sealing product 40 is applied in the groove 60 before the mould is mounted. The sealing product may be applied on one or more of the surfaces of the groove 60, which are the first surface 21, the second surface 22 forming the bottom of the groove and the third surface 63 of the outer edge 61.

According to fig. 7B, the inner edge 11 and the outer edge 61 are subsequently shortened (for example by scraping excess sand when the part 1 is made of agglomerated sand) in order to adjust the contact between the mould part 1 and the rail 30 in a desired manner. In so doing, the thickness of the inner edge 11 and the outer edge 61 is from E_B0To become E_B1And a recess R between the seat 13 and the rail-facing surface 45 of the sealing product 40₀Down to the value R₁. For good adjustment of the mould with the track, the inner edge 11 and the outer edge 61 are shortened to the same thickness E_B1。

Referring to fig. 7C and 7D, the mould part 1 is next mounted on the rail 30 and preheating the mould before casting the metal causes expansion of the sealing product 40 which then fills the volume of the groove 60.

The outer edge 61 separates the sealing product 40 from the outside of the mould, avoiding any overflow of the sealing product to the outside of the groove 60 to the outside of the mould during the expansion of the sealing product.

The inner edge 11 separates the sealing product 40 from the mould cavity 102, avoiding any direct contact between the metal and the sealing product during the subsequent step of casting the metal into the mould.

Depression R between seat 13 and surface 45 of the sealed product₀Advantageously chosen so as to allow a predetermined shortening of the inner edge 11 and the outer edge 61 so as to position the mould part 1 at a desired distance from the rail 30. In other words, the inner edge 11 and the outer edge 61 must be able to be shortened as desired without compromising the densityThe package 40 contacts the track before expanding. When the inner edge 11 and the outer edge 61 are shortened, the sealing product 40 is thus kept spaced apart from the rail 30 by the recess R₁。

With reference to figures 8A, 8B, 8C and 8D, the groove 60 may be of different shapes as long as there is continuity of the inner and outer edges 11, 61 delimiting the groove, it being understood that the height of said edges may vary along the groove according to the thickness of the sand to be removed to adjust the mould.

The grooves 60 may be, for example, circular, polygonal, or alternatively angled.

Fig. 9 shows a mold component whose seat 13 includes two grooves 60, each separated from the mold cavity by an inner edge 11 and from the exterior of the mold by an outer edge 61.

Prior to mounting the mould, the sealing product 40 is applied in the groove 60. The sealing product 40 covers the bottom 22 of the groove and partly the first surface 21 of the inner edge 11 and the third surface 63 of the outer edge 61.