Laser beam welding machine

Abstract

The invention relates to a welding machine (1) for welding at least two parts to be welded (2) which is configured to be movable along said parts to be welded (2), wherein the welding machine (1) extends in a longitudinal main direction of elongation (L) and comprises at least one pair of drive wheels (26) for moving said welding machine (1) relative to the parts to be welded (2), wherein the welding machine (1) comprises at least one welding device (30) for welding the at least two parts to be welded (2), and the welding device (30) comprises at least one means (32) for channeling a laser beam so as to weld the parts to be welded (2).

Description

[0001] Description

[0002] Title: Laser beam welding machine

[0003] The present invention relates to welding machines for welding together constituent parts of a transport tank, for example for liquefied gas.

[0004] Current welding machines include drive wheels and a drive member capable of rotating at least the drive wheels along the workpieces to be welded. Welding machines usually include welding wheels to weld the workpieces. The welding wheels are supplied with electric current while the welding machine is moving by means of an electric current unit, ensuring the welding of the workpieces. Welding with welding wheels is particularly effective for welding workpieces made of Invar™.

[0005] Invar™ has interesting resistance properties, particularly for use in a transport tank, for example for liquefied gas, and allows, among other things, to guarantee optimal transport of said liquefied gas. However, although it is efficient, invar™ is expensive and its use therefore generates significant manufacturing costs for the manufacturer. Thus, new alloys are trying to be used to replace invar™. For example, a high manganese alloy can replace invar™ in tanks, and has an expansion coefficient between that of invar™ and that of stainless steel, but with a lower cost. However, such a high manganese alloy is complex to weld with current welding machines.

[0006] Therefore, the use of high manganese alloy instead of Invar™ requires the development and use of suitable welding machines.

[0007] The aim of the present invention is therefore to propose a welding machine capable of welding alloys with a high manganese content while maintaining a compact welding machine.

[0008] The invention therefore relates to a laser beam welding machine for at least two parts to be welded, configured to be movable along said parts to be welded, the welding machine extending in a longitudinal main elongation direction and comprising at least one pair of drive wheels intended to set said welding machine in motion relative to the parts to be welded, the welding machine comprising at least one device for laser beam welding of the at least two parts to be welded, the welding device comprising at least one means intended to channel a laser beam capable of welding the parts to be welded.

[0009] The welding machine according to the invention can be used for example to weld two raised edges together and / or with an anchoring wing of a waterproof membrane constituting a wall of a tank for storing and / or transporting cryogenic products such as liquefied natural gas. For example, the welding machine can weld raised edges of two adjacent parts called, first part to be welded and second part to be welded, in order to form the waterproof membrane of the wall of the tank for storing and / or transporting cryogenic product. Alternatively, the welding machine can weld at least one of the raised edges with the anchoring wing, forming a third part to be welded, arranged between the two raised edges of the two adjacent parts. It is therefore understood that the part to be welded can be one of the raised edges or the anchoring wing.

[0010] For this purpose, the welding machine comprises at least the pair of drive wheels ensuring, by means of a drive member, the movement of the welding machine along the parts to be welded in a rectilinear welding direction, otherwise called the direction of advance of the welding machine. The drive member may be, for example, an electric, hydraulic, pneumatic or even mechanical drive member. Preferably, the drive member in the context of the invention is an electric motor.

[0011] Advantages of using a laser beam to weld the parts to be welded include that it allows alloys such as high manganese alloys to be welded. Thus, the invention provides a compact welding machine capable of welding a greater variety of alloys and also allowing alloys of different types to be welded together.

[0012] According to a characteristic of the invention, the welding machine comprises at least one drive member capable of rotating at least one of the drive wheels.

[0013] According to a characteristic of the invention, the means intended to channel the laser beam comprises at least one focusing lens, a reflection member and at least one circulation conduit surrounding the laser beam.

[0014] It is understood that the focusing lens allows the laser beam conveyed, for example, to be focused by means of an optical fiber. The circulation duct also allows a circulation path of the laser beam to be protected so that the latter is not disturbed by the external environment. The reflection member allows, among other things, the laser beam to be reflected without modifying its focal length. Such an optical fiber can be a component of the welding machine in that it transports the laser beam to the focusing lens. According to an exemplary embodiment, this optical fiber is a double-core fiber. Such an optical fiber has a fiber core, otherwise called an internal fiber, which channels the high-power laser beam, and a peripheral fiber to the fiber core, otherwise called an external fiber which surrounds the internal fiber.The laser beam is channeled into this outer optical fiber and its power is lower than that carried by the inner optical fiber.

[0015] Note that the reverse is also possible, that is, a situation where the outer fiber channels the high-power laser beam, while the fiber core or inner fiber channels the laser beam of lower power than that carried by the outer fiber.

[0016] The laser beam according to the invention can be characterized in that it comprises a beam core and a ring surrounding the beam core. According to a first exemplary embodiment, the beam core channels a beam portion that is more powerful than another beam portion channeled by the ring. According to a second exemplary embodiment, the beam core channels a beam portion that is less powerful than another beam portion channeled by the ring.

[0017] Such a laser beam, having a beam core and a ring, makes it possible to limit projections near the weld bead. Such a beam has a second advantage in that it makes it possible to obtain a wider final weld bead, without having to oscillate the laser beam, such an option also tending to increase projections.

[0018] According to an optional aspect of the invention, the reflection member(s) is / are for example a mirror. Advantageously, the welding machine comprises a means for adjusting the position of the reflection member, which makes it possible to adjust the positioning of the laser beam on the parts to be welded. According to one example, the reflection member comprises at least one material resistant to the heat of the laser beam, such a material being in particular quartz. Alternatively or additionally, the reflection member may comprise a cooling system configured to maintain the temperature of the reflection member below a temperature threshold. These arrangements make it possible to avoid any deformation, which would deteriorate the quality and / or the position of the beam.

[0019] According to a characteristic of the invention, the laser beam circulation conduit extends from the focusing lens to at least one welding zone of the parts to be welded.

[0020] We understand that the welding zone corresponds to the area of ​​the parts to be welded intended to receive the laser beam. We also understand that the welding zone evolves as the welding machine advances along the parts to be welded.

[0021] According to a characteristic of the invention, the reflection member is arranged in the circulation duct between the focusing lens and the welding zone.

[0022] According to an optional characteristic of the invention, the means intended to channel the laser beam comprises a plurality of reflection members, in particular three reflection members.

[0023] In the case of three reflection members, each of them is for example arranged so as to orient the laser beam in an output direction orthogonal, or generally orthogonal, to an input direction of the laser beam, the latter being the direction along which the laser beam extends before it strikes the reflection member.

[0024] According to an optional feature of the invention, the welding machine is configured so that the focusing lens is arranged vertically above a weld bead to be produced by the laser beam welding device.

[0025] In the case of a tank which comprises at least two parts to be welded, these two parts each having an edge raised at 90°, the laser beam directly coming from the focusing member extends in a plane in which at least one of the raised edges is inscribed. Thanks to these three mirrors, the invention makes it possible to return such a laser beam so that it attacks the raised edge along a direction substantially perpendicular to a plane in which at least the raised edge is inscribed. Such an organization of the reflection members and / or the focusing lens makes it possible to provide a more compact welding machine, with improved ergonomics. This organization makes it possible to produce a welding machine which is less high and less wide than known machines.

[0026] According to a characteristic of the invention, the circulation duct is bent so as to form an angular portion of the circulation duct, the reflection member being arranged in the angular portion of the circulation duct. Thus, it is understood that the reflection member is configured so as to modify the trajectory of the laser beam in the circulation duct so that it corresponds to the shape of the circulation duct.

[0027] According to a characteristic of the invention, the welding device comprises at least one housing forming a chamber around the welding zone, the housing being arranged at one end of the circulation conduit, opposite the focusing lens.

[0028] According to a characteristic of the invention, a neutral gas is distributed in the chamber formed by the housing, at least at the level of the welding zone.

[0029] According to one characteristic of the invention, the welding device comprises at least one pair of pressure rollers intended to press the parts to be welded against each other at the welding zone.

[0030] The pressure rollers are designed to press the parts to be welded together with a maximum gap between sheets of 0.2 mm. Furthermore, the pressure rollers are arranged in the chamber delimited by the housing.

[0031] A pair of pressure rollers is defined as two pressure rollers arranged on either side of the parts to be welded along a straight line perpendicular to a plane of the parts to be welded. Optionally, the pressure rollers can be cooled.

[0032] According to a characteristic of the invention, the laser beam is inscribed in a plane in which passes an axis of rotation of the at least two pressure rollers.

[0033] According to a feature of the invention, the welding device comprises a laser beam receiving element arranged in the housing and configured to be cooled. The laser beam receiving element makes it possible to absorb the residual optical energy of the laser beam and is connected to a cooling circuit in order to cool it.

[0034] Furthermore, the parts to be welded are arranged between the reflecting member and the receiving element along the path of the laser beam. It is then understood that the receiving element absorbs the residues of the laser beam once it has crossed the welding zone.

[0035] According to one example of the invention, the receiving element is made of a metallic or ceramic material.

[0036] According to a characteristic of the invention, the laser beam receiving element is configured to absorb a residual portion of the laser beam after it has passed through the parts to be welded.

[0037] According to an example of the invention, the welding device comprises another pair of pressure rollers on the other side of the welding zone, the laser beam being inscribed in a plane in which the axis of rotation of the at least two pairs of pressure rollers passes.

[0038] According to a characteristic of the invention, the focusing lens of the welding device is connected to an optical energy source external to the welding machine, in particular by an optical fiber.

[0039] According to a characteristic of the invention, the laser beam has a power of between 1200W and 6000W.

[0040] According to an example of the invention, for an alloy with a manganese content of at least 25%, the power of the laser beam is between 1250W and 6000W. For an alloy composed of at least 36% nickel, the power of the laser beam is between 1250W and 2500W.

[0041] According to a characteristic of the invention, the drive wheels are configured to move the welding machine along the parts to be welded at a speed of between 2m / min and 8m / min.

[0042] According to an example of the invention, for an alloy with a manganese content of at least 25%, the feed rate of the welding machine is between 2m / min and 5.5m / min. For an alloy composed of at least 36% nickel, the feed rate of the welding machine is between 2m / min and 4.8m / min. According to a characteristic of the invention, the drive wheels each extend in a plane intersecting with a plane of the parts to be welded, the intersecting plane of at least one of the drive wheels being distinct from a plane perpendicular to the plane of the parts to be welded.

[0043] According to a characteristic of the invention, at least two pairs of drive wheels are arranged on either side of the housing of the welding device in a longitudinal direction of the welding machine.

[0044] According to an example of the invention, the pairs of drive wheels are desynchronized in rotation relative to each other. In other words, the two pairs of drive wheels are capable of being driven in rotation by the drive member at different speeds from each other.

[0045] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description given below for information purposes in relation to drawings in which:

[0046] [Fig 1] is a general perspective view of a welding machine according to the invention capable of welding parts to be welded;

[0047] [Fig 2] is a close-up view of a welding device of the welding machine of Fig. 1;

[0048] [Fig 3] is a close-up view of another embodiment of the means for channeling the laser beam;

[0049] [Fig 4] is a close-up view of a housing of the welding device of Figure 2.

[0050] It should first be noted that while the figures set out the invention in detail for its implementation, these figures can of course be used to better define the invention, where appropriate. It should also be noted that these figures only set out examples of embodiments of the invention. Finally, the same references designate the same elements in all the figures.

[0051] Figure 1 illustrates a welding machine 1 configured to move along at least two parts to be welded 2. More precisely, the parts to be welded 2 are for example strips and constitute a sealed membrane 6 of a wall 8 of a storage and / or transport tank for products maintained in the liquid state at a temperature below -100°C at atmospheric pressure, for example liquefied natural gas.

[0052] The welding machine 1 may for example allow a first raised edge 4 and a second raised edge 4 of a first adjacent welding part 2a and a second adjacent welding part 2b to be welded directly against each other. According to another example of the invention, the welding machine may weld at least one of the raised edges 4 of one of the first welding part 2a and / or the second welding part 2b, with an anchoring wing 12 forming a third welding part visible in FIGS. 2 and 4, said anchoring wing 12 being arranged between two adjacent raised edges.

[0053] More particularly, the anchoring wing 12, visible in Figures 2 and 4, is anchored to an insulator belonging to the tank wall and is arranged between two adjacent raised edges. Such welding of at least two of the parts to be welded 2a, 2b forms a weld bead 14, visible in Figures 2 to 4, on at least one of the first raised edge 4 and / or the second raised edge, extending along a weld axis S. The weld bead 14 formed between the at least two parts to be welded 2 makes it possible, among other things, to ensure the seal between said parts to be welded 2, and thus contributes to the seal of the membrane 6 constituting the wall 8 of the tank for storing and / or transporting cryogenic products.

[0054] The welding machine 1 illustrated in Figure 1 comprises at least one body 16 which has a substantially parallelepiped shape and which extends in a main elongation direction parallel to a longitudinal direction L of the welding machine 1. The body 16 of the welding machine 1 comprises in particular a front end 18 and a rear end 20, opposite each other in the longitudinal direction L of the welding machine 1. It is further understood that the concept of front / rear of the body 16 of the welding machine 1 refers to a direction of advancement A of the welding machine 1 along the parts to be welded 2, parallel to the welding axis S and to the longitudinal direction L of said welding machine 1.Furthermore, the body 16 of the welding machine 1 comprises an upper face 22 and a lower face 24, opposite each other in a vertical direction V of the welding machine 1, perpendicular to its longitudinal direction L, the lower face 24 being the face of the body 16 of the welding machine 1 opposite the parts to be welded 2.

[0055] The welding machine 1 according to the invention, visible in figure 1, comprises at least one pair of drive wheels 26 intended to set the welding machine 1 in motion relative to the parts to be welded 2, and at least one drive member, not visible, capable of driving the at least one pair of drive wheels 26 in rotation.

[0056] More precisely, the at least one pair of drive wheels 26 is arranged at the lower face 24 of the body 16 of the welding machine 1 so that it is in contact with at least one of the parts to be welded 2. Thus, the rotation of the at least one pair of drive wheels 26 operated by the drive member allows said pair of drive wheels 26, arranged in contact with the parts to be welded 2, to generate the movement of the welding machine 1 along the parts to be welded 2 following a rectilinear translational movement parallel to the direction of advance A of the welding machine 1.

[0057] More precisely, each of the wheels of the pair of drive wheels 26 is in contact with one of the parts to be welded 2. According to the example of the invention illustrated, the welding machine 1 comprises a first pair of drive wheels 26a and a second pair of drive wheels 26b arranged respectively at the front end 18 and at the rear end 20 of the body 16 of the welding machine 1. It is further understood that the drive wheels 26 of each pair of drive wheels 26a, 26b are opposite each other in a transverse direction T of the welding machine 1, perpendicular to the longitudinal direction L and vertical direction V. Thus, the drive wheels 26 of the same pair of drive wheels extend on either side of the parts to be welded 2.

[0058] According to another example of the invention, the drive wheels each extend in a plane intersecting with a plane of the parts to be welded 2, and for at least one of the drive wheels the plane in which it extends is perpendicular to the plane of one of the raised edges 4. Such a characteristic in particular allows the welding machine to be held alone against side walls or against the upper wall of the tank during its movement. As mentioned previously, the welding machine 1 comprises at least one drive member ensuring the rotation of the drive wheels 26 and which can take the form of an electric, hydraulic, pneumatic or even mechanical drive member. Preferably, the drive member according to the invention is an electric motor.

[0059] The welding machine 1 according to the invention comprises at least one device 30 for welding the at least two parts to be welded 2, visible in FIG. 1. The welding device 30 comprises in particular at least one means 32 intended to channel a laser beam 34 so as to weld the parts to be welded 2.

[0060] The welding device 30 will now be described in more detail by means of Figures 2 to 4.

[0061] As mentioned previously, the welding device 30 comprises the means 32 intended to channel the laser beam 34 consisting of at least one focusing lens 36, a reflection member 38 and at least one circulation conduit 40 surrounding the laser beam 34. The focusing lens 36 makes it possible, among other things, to focus the laser beam 34 which is conveyed for example by optical fiber 51 from a laser source external to the welding machine 1 and here not visible, to the means intended to channel the laser beam 34. Thus, it is understood that the laser beam 34 coming from the focusing lens 36 is surrounded by the circulation conduit 40 such that the latter protects both a user of the welding machine 1 from the laser beam 34 and the laser beam 34 itself from the external environment which may disturb its trajectory.To this end, the circulation conduit 40 of the laser beam 34 extends from the focusing lens 36 to at least one welding zone 44 of the parts to be welded 2. By welding zone 44 is meant a portion on the parts to be welded 2 on which the weld bead 14 mentioned above is to be formed.

[0062] As particularly visible in Figure 2, the circulation duct 40 is bent so as to form an angular portion 46 of the circulation duct 40. Such a structure of the circulation duct 40 makes it possible in particular to optimize the dimensions of the welding machine 1 by limiting the size of said circulation duct 40 of the laser beam 34. The reflection member 38 is then arranged in the angular portion 46 of the circulation duct 40. In other words, the reflection member 38 is arranged in the circulation duct 40 between the focusing lens 36 and the welding zone 44. It is then understood that the reflection member 38 has the function of deflecting the rectilinear trajectory of the laser beam 34 at the outlet of the focusing lens 36.According to the illustrated example of the invention, the angular portion 46 of the circulation duct 40 forms a substantially right angle to the circulation duct 40 and the reflection member 38 is arranged in the angular portion 46 of the circulation duct 40 such that it deflects the laser beam 34 by 90° in order to follow the trajectory of the circulation duct 40. According to an example of the invention, the reflection member 38 is a mirror.

[0063] According to the invention, the welding device 30 comprises at least one housing 48 delimiting a chamber 50 around the welding zone 44, the housing 48 being arranged at one end of the circulation conduit 40, opposite the focusing lens 36. As visible in FIGS. 2 and 4, the housing 48 comprises an opening 52 configured to allow the passage of the parts to be welded 2 through the housing 48.

[0064] Furthermore, according to an example of the invention, the housing may comprise a device for projecting a neutral gas towards the welding zone so as to avoid oxidation of the weld bead which results from welding by the laser beam. The device for projecting a neutral gas is then at least partly positioned in the chamber 50.

[0065] Figure 3 illustrates an exemplary embodiment of the welding machine which comprises an optical fiber 51. This optical fiber 51 extends mainly along a direction which is inscribed in the plane of one of the raised edges 4. In other words, the laser beam arrives from above the area to be welded. The focusing lens 36 is thus vertically above the welding area 44.

[0066] Since the weld bead 14 is a through weld of the raised edges 4, the means 32 which is intended to channel the laser beam 34 comprises means for channeling the laser beam so as to strike the surface of the raised edge 4 perpendicularly.

[0067] Thus, the means 32 intended to channel the laser beam 34 comprises three reflection members 38a, 38b and 38c. The first reflection member 38a is immediately downstream of the focusing lens and it returns the laser beam 34 in an exit direction perpendicular to the entry direction which strikes the first reflection member 38a. The laser beam 34 then strikes a surface of a second reflection member 38b and the latter returns the laser beam 34 in an exit direction perpendicular to the entry direction which strikes the second reflection member 38b. The direction of this intermediate portion of the beam is then parallel, or substantially parallel, to the plane in which the raised edge 4 is inscribed.

[0068] The third reflection member 38c returns the laser beam 34 so that it strikes the raised edge 4. This third reflection member 38c returns the laser beam 34 in an exit direction perpendicular to the entry direction which strikes it at the entrance.

[0069] According to the invention, the housing 48 of the welding device 30 is dimensioned such that it is capable of housing at least one pair of pressure rollers 54 intended to press the parts to be welded 2 against each other at the welding zone 44. In other words, the pressure rollers 54 of the at least one pair of pressure rollers 54 are arranged on either side of the welding zone 44 such that they press the parts to be welded 2 against each other.

[0070] According to an example of the invention, the parts to be welded 2 are pressed against each other in such a way that the welding zone 44 has a maximum clearance between sheets of 0.2 mm spacing between said parts to be welded 2. Furthermore, it is understood that the pressure rollers 54 are connected to a system for pressurizing the pressure rollers 54 belonging to the welding machine, in order to press them against the parts to be welded 2 at the welding zone 44.

[0071] Furthermore, according to the invention, the laser beam 34 is inscribed in a plane in which the axis of rotation R of the at least two pressure rollers 54 passes, visible in FIG. 4. Advantage is taken of such a characteristic in that it allows the laser beam 34 to pass through the welding zone 44 where the parts to be welded 2 are in the most contact with each other.

[0072] According to the example of the invention illustrated, the two pressure rollers 54 mentioned above are called first pair 54a of pressure rollers 54. According to this example, the welding machine 1 comprises a second pair 54b of pressure rollers 54. The first pair 54a and the second pair 54b of pressure rollers 54 are on either side of the laser beam 34. The pressure rollers 54 of the second pair of pressure rollers 54b each have an axis of rotation R which is inscribed in the common plane with the axes of rotation R of the other pressure rollers 54 of the first pair of pressure rollers 54, and optionally with the laser beam 34. It is then understood that the pressure rollers 54 of the second pair 54b of pressure rollers are arranged on the other side of the welding zone 44 relative to the first pair 54a of pressure rollers 54, according to the vertical direction V of the welding machine 1.This makes it possible to optimize the plating of the parts to be welded 2 at the welding zone 44.

[0073] According to a characteristic of the invention, the welding device 30 comprises a receiving element 56 for the laser beam 34 arranged in the housing 48 and configured to be cooled, for example by means of a cooling circuit, not visible. In other words, the receiving element 56 is configured to absorb a residual portion of the laser beam 34 at the end of its passage through the parts to be welded 2. It is then understood that the parts to be welded are arranged between the focusing lens 36 and the receiving element 56 along the trajectory of the laser beam 34. According to an example of the invention, the receiving element 56 is made of metallic material, for example copper, or of ceramic material. It is understood, however, that the receiving element 56 may be made of any material capable of being cooled.

[0074] Advantage is taken of the welding machine 1 according to the invention in that the use of a laser beam 34 to weld the parts to be welded 2 makes it possible to weld different metals with the same welding machine 1. For example, the welding machine 1 according to the invention makes it possible to weld parts to be welded 2 made of Invar™ or even of an alloy with a high manganese content. High manganese content is understood to mean a content of at least 25% in an alloy.

[0075] For example, for an alloy with a manganese content of at least 25%, the power of the laser beam 34 is between 1250W and 6000W. For an alloy composed of at least 36% nickel, the power of the laser beam 34 is between 1250W and 25000W.

[0076] Also, depending on the type of metals to be welded, the drive wheels 26 will adapt their rotation speed in order to optimize the welding of the parts to be welded 2. For example, for an alloy with a manganese content of at least 25%, the feed speed of the welding machine 1 is between 2m / min and 8m / min, advantageously 5.5m / min. For an alloy composed of at least 36% nickel, the feed speed of the welding machine 1 is between 2m / min and 4.8m / min.

[0077] The welding machine, as just described in each of the embodiments, may comprise a so-called “double core” optical fiber 51. This optical fiber thus comprises an internal fiber which forms the core of the fiber and an external fiber which surrounds the core. This organization makes it possible to focus the laser beam 34 which circulates in the core by means of the focusing lens 36 so as to deliver a beam power close to 6000W, the distance of the focusing lens 36 relative to the peripheral zone of the optical fiber 51 making it possible to deliver a laser beam 34 of power less than 6000W, which significantly limits the projection of droplets on the sides of the weld bead 14.

[0078] This choice also makes it possible to do without any laser beam oscillation device because the beam width meets the specifications. The welding machine 1 is therefore simpler and more compact.

[0079] According to one option, the welding machine may include a camera system such as a camera. Such a system makes it possible to monitor the quality of the weld. This camera system may point directly at the welding zone 44, so as to observe the creation of the weld. Alternatively, this camera system may point towards the rear of the welding machine so as to observe the weld after the welding machine has passed.

[0080] The invention as just described cannot, however, be limited to the means and configurations exclusively described and illustrated, and also applies to all equivalent means or configurations and to any combination of such means or configurations.

Claims

CLAIMS 1. Laser beam welding machine (1) for at least two parts to be welded (2), configured to be movable along said parts to be welded (2), the welding machine (1) extending in a longitudinal main elongation direction (L) and comprising at least one pair of drive wheels (26) intended to set said welding machine (1) in motion relative to the parts to be welded (2), the welding machine (1) comprising at least one device (30) for welding by laser beam the at least two parts to be welded (2), the welding device (30) comprising at least one means (32) intended to channel a laser beam (34) capable of welding the parts to be welded (2).

2. Welding machine (1) according to claim 1, comprising at least one drive member capable of driving at least one of the drive wheels (26) in rotation.

3. Welding machine (1) according to any one of claims 1 or 2, wherein the means (32) for channeling the laser beam (34) comprises at least one focusing lens (36), a reflection member (38) and at least one circulation conduit (40) surrounding the laser beam (34).

4. Welding machine (1) according to claim 3, wherein the circulation conduit (40) of the laser beam (34) extends from the focusing lens (36) to at least one welding zone (44) of the parts to be welded (2).

5. Welding machine (1) according to claim 4, wherein the reflecting member (38) is arranged in the circulation duct (40) between the focusing lens (36) and the welding zone (44).

6. Welding machine (1) according to any one of claims 3 to 5, wherein the means (32) for channeling the laser beam (34) comprises a plurality of reflection members (38), in particular three reflection members (38).

7. Welding machine (1) according to any one of claims 3 to 6, configured so that the focusing lens (36) is arranged vertically above a weld bead (14) to be produced by the laser beam welding device (30).

8. Welding machine (1) according to any one of claims 4 to 7, in which the welding device (30) comprises at least one housing (48) forming a chamber (50) around the welding zone (44), the housing (48) being arranged at one end of the circulation conduit (40), opposite the focusing lens (36).

9. Welding machine (1) according to any one of claims 1 to 8 in combination with claim 4, wherein the welding device (30) comprises at least one pair of pressure rollers (54) intended to press the parts to be welded (2) against each other at the welding zone (44).

10. Welding machine (1) according to claim 9, in which the laser beam (34) is inscribed in a plane in which an axis of rotation (R) of the at least two pressure rollers (54) passes.

11. Welding machine (1) according to claim 8, wherein the welding device (30) comprises a receiving element (56) for the laser beam (34) arranged in the housing (48) and configured to be cooled, said receiving element (56) for the laser beam (34) being configured to absorb a residual portion of the laser beam (34) after its passage through the parts to be welded (2).

12. Welding machine (1) according to any one of claims 1 to 11, in which the laser beam (34) has a power of between 1200W and 6000W.

13. Welding machine (1) according to any one of claims 1 to 12, wherein the drive wheels (26) are configured to move the welding machine (1) along the parts to be welded at a speed of between 2m / min and 8m / min.

14. Welding machine (1) according to any one of claims 1 to 13, in which the drive wheels (26) each extend in a plane intersecting with respect to a plane of the parts to be welded (2), the intersecting plane of at least one of the drive wheels (26) being distinct from a plane perpendicular to the plane of the parts to be welded (2).

15. Welding machine (1) according to any one of claims 1 to 14 in combination with claim 8, comprising at least two pairs of drive wheels (26) which are arranged on either side of the housing (48) of the welding device (30) in a longitudinal direction (L) of the welding machine (1).

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