Welding machine

Abstract

To provide a welding machine in which the difference in tangential speed between the drive wheels and welding wheels due to the wear of the welding wheels does not affect the quality of the welding of the parts to be welded and which requires a longer replacement time for the welding wheels.SOLUTION: The invention relates to a welding machine (1) configured to move along at least two parts to be welded, the welding machine (1) comprises: at least one drive wheel (20) intended to move the welding machine (1) relative to the parts to be welded; at least one actuator (22) capable of rotating the drive wheel (20); and at least one welding wheel (26) capable of welding the parts to be welded by rolling against at least one of the parts to be welded, with the welding wheel (26) being free to rotate relative to the drive wheel (20).SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The field of the present invention is the field of welding machines comprising an electrode in the form of a welding wheel for welding weld parts together.

Background Art

[0002] Current welding machines comprise a drive wheel, a welding wheel for welding weld parts together, and an actuator capable of rotating the drive wheel and the welding wheel along the weld parts. More specifically, the actuator can rotate the welding wheel and the drive wheel at the same rotational speed, and as a result, the welding machine moves along the weld parts while performing the welding operation.

[0003] One problem with such welding machines is, in particular, the fact that the welding wheel wears when welding the weld parts and, in particular, loses those constituent materials located around, i.e., in the vicinity of the contact area with the weld parts. In other words, the diameter of the welding wheel decreases as the welding machine advances and thus as the weld parts are welded. Therefore, the decrease in the diameter of the welding wheel causes a significant difference in the tangential speed between the welding wheel and the drive wheel.

[0004] Such a difference in the tangential speed between the welding wheel and the drive wheel can cause a slipping phenomenon in which the welding wheel slides along the weld parts. And such slipping of the welding wheel along the weld parts can cause a sealing problem due to the lack of welding in the vicinity of the slipping area. Furthermore, due to the problem of slipping of the welding wheel, it is necessary to regularly replace the welding wheel when using the welding machine.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, the object of the present invention is to overcome the aforementioned problems by designing a welding machine in which the difference in tangential velocity between the drive wheel and the welding wheel due to wear of the welding wheel does not affect the quality of the weld on the part to be welded, and which requires a longer replacement interval for the welding wheel. [Means for solving the problem]

[0006] Accordingly, the present invention relates to a welding machine configured to move along at least two parts to be welded, the welding machine comprising at least one drive wheel intended to move the welding machine relative to the parts to be welded, at least one actuator capable of rotating the drive wheel, and at least one welding wheel capable of welding the parts to be welded by rolling against at least one of the parts to be welded, the welding machine characterized in that the welding wheel rotates freely relative to the drive wheel.

[0007] The welding machine according to the present invention can be used, for example, to weld two weldable parts of a sealing membrane that forms part of the wall of a tank for storing and / or transporting cryogenic products such as liquefied natural gas. More specifically, the welding machine enables welding of raised edges of two adjacent weldable parts, called a first weldable part and a second weldable part, to form a sealing membrane of the wall of a tank for storing and / or transporting cryogenic products. For this purpose, the welding machine is equipped with at least a drive wheel, which uses an actuator to ensure that the welding machine moves along the weldable parts in a linear welding direction, also called the direction of travel of the welding machine. The actuator may be, for example, a hydraulic, pneumatic, or mechanical actuator. Preferably, the actuator within the scope of the present invention is an electric actuator.

[0008] The welding wheel enables welding by contacting one of the parts to be welded. More specifically, when welding parts, the movement of the welding machine relative to the parts rotates the welding wheel relative to one of the parts, and the current passing through the welding wheel allows a weld bead to form on the parts. In more detail, the welding wheel rotates independently of the rotation of the drive wheel driven by the actuator.

[0009] According to one feature of the present invention, the welding wheel is rotated as the welding machine moves by bringing the welding wheel into contact with one of the parts to be welded.

[0010] In this case, the actuator ensures that the drive wheel rotates, allowing the welding machine to move relative to the parts to be welded, and this movement of the welding machine helps to rotate the welding wheel when it is in contact with at least one of the parts to be welded.

[0011] According to one feature of the present invention, the welding machine comprises at least two drive wheels and two actuators separate from each other, wherein each drive wheel is driven by one of the actuators.

[0012] The front and rear ends of the welding machine are defined, facing each other in the direction of travel of the welding machine. According to one example of the present invention, one of the drive wheels can be positioned at the front end of the welding machine and the other drive wheel can be positioned at the rear end of the welding machine. Furthermore, according to another example of the present invention, both of at least two drive wheels can be positioned at either the front or rear end of the welding machine.

[0013] According to one feature of the present invention, one of the drive wheels is rotated at a first rotational speed by one actuator, and the other drive wheel is rotated at a second rotational speed by another actuator, wherein the first and second rotational speeds are different from each other. Alternatively, the first and second rotational speeds of the drive wheels are the same.

[0014] According to one example of the present invention, one drive wheel, for example, a drive wheel located at the front end of a welding machine, is rotated at a first speed by one of the actuators, and this first speed is faster than the second rotational speed of the other drive wheel, for example, a drive wheel located at the rear end of a welding machine, under the influence of the other actuator. In this example, the speed of one drive wheel located at the front end of the welding machine and the other drive wheel located at the rear end of the welding machine are restricted.

[0015] Another possibility covered by the present invention is that one drive wheel, for example, a drive wheel located at the front end of a welding machine, is rotated at a speed determined by one actuator, while the other drive wheel, for example, a drive wheel located at the rear end of a welding machine, is controlled based on the torque of the other actuator. In this example, the drive wheel located at the front end of the welding machine and the other drive wheel located at the rear end of the welding machine are torque-regulated.

[0016] These two configurations advantageously allow tension to be applied to the raised edge of the part to be welded, which is positioned between the drive wheels, and then facilitate welding of the part by the welding wheels. The second configuration allows for sensing the sliding of the actuator to confirm that the part to be welded is under tension. This second configuration is also more reliable.

[0017] According to an alternative embodiment of the present invention, the welding machine comprises at least two drive wheels that are separate from each other, and an actuator, the two drive wheels being rotated by an actuator common to these two drive wheels.

[0018] In this alternative embodiment of the present invention, both drive wheels can be located at the front or rear end of the welding machine and can be rotated by the same actuator. According to another alternative embodiment of the present invention, one drive wheel can be located at the front end of the welding machine and the other drive wheel can be located at the rear end of the welding machine, and the drive wheels are rotated by the same actuator.

[0019] According to one feature of the present invention, the welding wheel is positioned in the welding machine in the longitudinal direction of the welding machine, between one of the drive wheels and another drive wheel.

[0020] It is understood that the longitudinal direction of a welding machine corresponds to its direction of travel, i.e., the welding direction. It is understood that this characteristic applies when at least one of the drive wheels is located at the front end of the welding machine and the other drive wheel is located at the rear end of the welding machine.

[0021] According to one feature of the present invention, the welding wheel is positioned in a plane common to at least one of the drive wheels of the welding machine. According to a preferred embodiment, the welding wheel is positioned in a plane common to all of the drive wheels of the welding machine.

[0022] Alternatively, the welding wheels are positioned in a plane different from the plane on which the welding machine's drive wheels extend. According to one example of the present invention, each drive wheel is positioned in a plane intersecting the plane on which the welding machine's welding wheels extend, thereby improving the holding ability of the welding machine with respect to the part to be welded.

[0023] According to one feature of the present invention, the welding machine comprises at least one component for pressing at least one welding wheel against one of the parts to be welded.

[0024] The pressing component can take the form of a cylinder capable of pressing at least one welding wheel against one of the parts to be welded. Such a pressing component can compensate for any play between one of the parts to be welded and the welding wheel resulting from wear of the welding wheel when welding the parts to be welded. According to another example of the present invention, the pressing component can take the form of a piston or an elastic spring.

[0025] According to one feature of the present invention, the welding machine can include at least one component for pressing the drive wheel. In such a configuration, the purpose of the component for pressing the drive wheel is, on the one hand, to ensure that the welding machine is locked at a predetermined position on the welding target component, and on the other hand, to ensure that the drive wheel is pressed against the welding target component, thereby ensuring the movement of the welding machine by opening and closing on the welding target component.

[0026] According to one feature of the present invention, the welding machine includes a first welding wheel and a second welding wheel that face each other in the lateral direction of the welding machine.

[0027] More specifically, the lateral direction of the welding machine is perpendicular to the longitudinal direction of the welding machine. Therefore, it is understood that the first welding wheel and the second welding wheel are arranged on both sides of the welding target component. More specifically, the first welding wheel is configured to face the first raised edge of the first welding target component, and the second welding wheel is configured to face the second raised edge of the second welding target component. Thus, a more reliable welded joint can be formed between the first welding target component and the second welding target component, and therefore, the sealing between them is strengthened.

[0028] According to an alternative form of the present invention, the first welding wheel and the second welding wheel rotate when the welding machine moves, and the welding machine includes at least one component for synchronizing the rotation of the first welding wheel with the rotation of the second welding wheel.

[0029] According to one feature of the present invention, the first welding wheel and the second welding wheel rotate at the same tangential speed when the welding machine moves.

[0030] According to an alternative feature, the welding wheels have different diameters from each other, and the tangential speeds of the first welding wheel and the second welding wheel are different from each other.

[0031] According to one feature of the present invention, a welding machine can weld at least two raised edges of two weldable parts of a sealed membrane that forms part of a tank for storing and / or transporting cryogenic products. More specifically, the tank may be a tank for storing and / or transporting liquefied natural gas. It is also understood that the two weldable parts are the first weldable part and the second weldable part described above.

[0032] Further features, details, and advantages of the present invention will become more clearly apparent from the description provided below as an example, with reference to the drawings. [Brief explanation of the drawing]

[0033] [Figure 1] This is a schematic perspective view of a tank for storing and / or transporting cryogenic products, including at least two weldable parts that form part of the tank's sealing membrane. [Figure 2] This is a perspective view of a welding machine according to the present invention, which can weld the raised edges of two parts to be welded. [Figure 3] Figure 2 is a partial side view of a welding machine comprising at least one drive wheel and at least one welding wheel. [Figure 4] This is a schematic diagram of the welding machine shown in Figure 2 according to the first embodiment. [Figure 5] This is a schematic diagram of the welding machine shown in Figure 2 according to the second embodiment. [Figure 6] This is a schematic diagram of the welding machine shown in Figure 2 according to the third embodiment. [Modes for carrying out the invention]

[0034] First, it should be noted that while the drawings disclose the invention in detail for its implementation, these drawings can also be clearly used to better define the invention where applicable. It should also be noted that these drawings only disclose embodiments of the invention. Finally, the same reference numerals indicate the same elements throughout the drawings.

[0035] Figure 2 shows a welding machine 1 configured to move along at least two weldable parts 2, each having at least one raised edge 4. More specifically, the weldable parts 2 form part of a sealing membrane 6 of the wall 7 of a tank 8 for storing and / or transporting cryogenic products, such as liquefied natural gas.

[0036] The welding machine 1 then welds the adjacent first weldable part 2a and second weldable part 2b at the first raised edge 4a and second raised edge 4b, respectively. Preferably, the welding is performed by a fixed wing fixed to an insulator that belongs to the wall 7 of the tank 8 and is positioned between the two adjacent raised edges. Such welding of the first weldable part 2a and the second weldable part 2b forms a weld bead 10, as shown in Figure 3, on the first raised edge 4a and the second raised edge 4b ​​extending along the welding axis S. The weld bead 10 formed between the two weldable parts 2, in particular, allows for a seal between the weldable parts 2 and thus helps to seal the membrane 6 that forms part of the wall 7 of the tank 8 for storing and / or transporting cryogenic products.

[0037] In particular, the welding machine 1 shown in Figures 2 and 3 has a substantially parallelepiped shape and extends in a main extension direction P parallel to the longitudinal direction L of the welding machine 1. The welding machine 1 comprises a front end 12 and a rear end 14 that face each other in the longitudinal direction L of the welding machine 1. The front / rear concept of the welding machine 1 can also be understood as referring to the direction of travel A of the welding machine 1, which is parallel to the welding axis S and the longitudinal direction L of the welding machine 1. Furthermore, the welding machine 1 comprises an upper surface 16 and a lower surface 18 that face each other in the vertical direction V of the welding machine 1 perpendicular to its longitudinal direction L, with the lower surface 18 being the surface of the welding machine 1 facing the part to be welded 2.

[0038] The welding machine 1 according to the present invention comprises at least one drive wheel 20 intended to move the welding machine 1 relative to a part 2 to be welded, and at least one actuator 22, as shown in Figures 4 to 6, which can rotate at least one drive wheel 20.

[0039] More specifically, the drive wheel 20 is positioned on the underside 18 of the welding machine 1 so as to contact at least one of the parts to be welded 2. Thus, the rotation of the drive wheel 20 performed by the actuator 22 allows the drive wheel 20, positioned in contact with one of the parts to be welded 2, to generate the movement of the welding machine 1 along the parts to be welded 2 in a linear translational motion parallel to the direction of travel A of the welding machine 1. More specifically, the drive wheel 20 is in contact with one of the raised edges 4 on one of the parts to be welded 2. According to an illustrated example of the present invention, the welding machine 1 comprises four drive wheels 20 as shown in Figures 4 to 6.

[0040] Then, a first pair 20a of drive wheels 20 located at the front end 12 of the welding machine 1 and a second pair 20b of drive wheels 20 located at the rear end 14 of the welding machine 1 are defined.

[0041] In this configuration, each of the first pair of drive wheels 20a faces each other in the lateral direction T of the welding machine 1, which is perpendicular to the longitudinal direction L and the vertical direction V. It is understood that each of the first pair of drive wheels 20a is configured to be positioned on both sides of the raised edge of the part to be welded. More specifically, according to the example of the present invention shown in Figures 2 to 6, the first front drive wheel 201 of the first pair of drive wheels 20a is positioned facing the first raised edge 4a of the first part to be welded 2a, and the second front drive wheel 202 of the first pair of drive wheels 20a is positioned facing the second raised edge 4b ​​of the second part to be welded 2b.

[0042] The welding machine 1 includes at least one pressing component 24 positioned between the first pair of drive wheels 20a of the drive wheels 20. The pressing component 24, in particular, enables the first pair of drive wheels 20a of the drive wheels 20 to be pressed against the workpiece to be welded, more specifically, against a raised edge. More specifically, the purpose of the pressing component 24 is to move the first front drive wheel 201 and the second front drive wheel 202 away from and toward the first raised edge of the first workpiece to be welded and the second raised edge of the second workpiece to be welded, respectively. This thus enables the welding machine 1 to be positioned on the raised edge and ensures that the drive wheels 20 are pressed against the raised edge in order to lock the welding machine 1 in place relative to the workpiece to be welded. It is understood that such pressing of the first pair 20a of the drive wheels 20 against the raised edge of the part to be welded helps to ensure the movement of the welding machine 1 while the first pair 20a of the drive wheels 20 are rotating.

[0043] Furthermore, the pressing component 24 ensures that the welding machine 1 is held against the workpiece when the welding machine 1 is stationary, i.e., when the drive wheel 20 is not being rotated by at least one actuator 22. According to an example of the present invention, the pressing component 24 can take the form of a piston, cylinder, or spring. Thus, in order to move the welding machine 1 away from the workpiece, it is understood that the drive wheel 20 is moved away from the workpiece, particularly by stopping the operation of the pressing component 24.

[0044] According to one feature of the present invention, the first front drive wheel 201 and the second front drive wheel 202 of the first pair 20a of the drive wheel 20 are arranged in a common plane L, T, which is hereafter referred to as plane R.

[0045] According to an alternative embodiment of the present invention not shown, each of the first front drive wheel and the second front drive wheel of the first pair of drive wheels extends into a plane that intersects the main longitudinal plane and the main transverse plane on which the welding machine extends. In this way, the grip of the welding machine on the part to be welded is increased.

[0046] It is understood that each of the features of the first front drive wheel 201 and the second front drive wheel 202 of the first pair 20a of drive wheels 20 can be applied, with necessary modifications, to the second pair 20b of drive wheels 20, in particular the first rear drive wheel 203 and the second rear drive wheel 204 of the second pair 20b of drive wheels 20, which are located at the rear end 14 of the welding machine 1.

[0047] Accordingly, according to one example of the present invention, the first pressing component 24a is positioned between the first front drive wheel 201 and the second front drive wheel 202 of the first pair 20a of the drive wheel 20, and the second pressing component 24b is positioned between the first rear drive wheel 203 and the second rear drive wheel 204 of the second pair 20b of the drive wheel 20.

[0048] Furthermore, advantageously, the drive wheels of the second pair 20b of the drive wheels 20 extend in a plane R together with the first pair 20a of the drive wheels 20. According to an alternative embodiment of the present invention not shown, the drive wheels of the second pair of drive wheels extend in a plane different from the plane in which the first pair of drive wheels extend.

[0049] As described above, the welding machine 1 is equipped with at least one actuator 22 to ensure the rotation of the drive wheel 20, and the actuator 22 can be in the form of a hydraulic, pneumatic, or mechanical actuator 22. Preferably, the actuator 22 according to the present invention is an electric motor. In this case, it is understood that the actuator 22 helps to move the welding machine 1 along the part to be welded 2 in the direction of travel A of the welding machine 1.

[0050] According to the first example of the present invention shown in Figure 4, the first actuator 22a rotates the first pair 20a of the drive wheels 20, and the second actuator 22b rotates the second pair 20b of the drive wheels 20. More specifically, the drive wheels 20 of the first pair 20a of the drive wheels 20 are rotated at a first rotational speed by the first actuator 22a, and the drive wheels 20 of the second pair 20b of the drive wheels 20 are rotated at a second rotational speed by the second actuator 22b.

[0051] According to one embodiment, the first rotational speed of the first pair 20a of the drive wheels 20 and the second rotational speed of the second pair 20b of the drive wheels 20 are different from each other. More specifically, the first rotational speed of the first pair 20a of the drive wheels 20 is faster than the second rotational speed of the second pair 20b of the drive wheels 20. The advantage of this feature is that it allows tension to be applied to the raised edge of the part to be welded, which is positioned between the first pair 20a of the drive wheels 20 and the second pair 20b of the drive wheels 20, and thus facilitates welding by at least one welding wheel 26 of the welding machine 1.

[0052] Alternatively, the first rotational speed of the first pair 20a of the drive wheels 20 is the same as the second rotational speed of the second pair 20b of the drive wheels 20.

[0053] According to a second embodiment of the present invention shown in Figure 5, the welding machine 1 may be equipped with four actuators 22 that are separate from each other, and each actuator 22 may rotate one of the four drive wheels 20 of the welding machine 1. Thus, it is understood that the first front drive wheel 201 of the first pair 20a of the drive wheels 20 may rotate at a rotational speed equal to or different from that of the second front drive wheel 202 of the first pair 20a of the drive wheels 20. Similarly, it is understood that the first rear drive wheel 203 of the second pair 20b of the drive wheels may rotate at a rotational speed equal to or different from that of the second rear drive wheel 204 of the second pair 20b of the drive wheels.

[0054] The advantage of this configuration of the welding machine 1 is that the rotational speed of each drive wheel 20 of the welding machine 1 can be more precisely matched, independently of the other drive wheels 20. This allows for more effective tensioning of the raised edges of the two parts to be welded, thereby facilitating welding by the welding wheel 26, and thus enabling more reliable welds between the two parts. Furthermore, this configuration of the welding machine 1 allows for the absence of bearings in the actuator 22, thus resulting in a lighter weight and reduced footprint of the welding machine 1.

[0055] At least one welding wheel 26 of the welding machine can weld the first raised edge 4a and the second raised edge 4b ​​of the first part to be welded 2a and the second part to be welded 2b, respectively, to form the weld bead 10 described above in Figures 2 and 3. To perform the welding operation, the welding wheel 26 is configured to receive current when the welding machine 1 is in operation. According to one feature of the present invention, the welding wheel 26 can rotate freely with respect to at least one drive wheel 20 of the welding machine 1. More specifically, according to an example of the present invention, the welding wheel 26 rotates freely with respect to each of the drive wheels 20 of the first pair 20a and the second pair 20b of the drive wheels 20.

[0056] At this time, as the welding machine 1 moves toward one of the parts to be welded, more specifically toward one of the raised edges of one of the parts to be welded, via direct contact of the welding wheel 26, the welding wheel 26 rotates. Therefore, it is understood that the actuator 22 of the drive wheel 20 of the welding machine 1 does not directly act on the rotation of the welding wheel 26. In other words, the rotation of the welding wheel 26 depends, on the one hand, on contact with one of the parts to be welded, and on the other hand, on the other hand, on the movement of the welding machine 1 along the part to be welded, generated by the drive wheel 20 and actuator 22 of the welding machine.

[0057] When the welding machine 1 is used, the rotation of the welding wheel 26 relative to one of the parts to be welded causes material loss around the welding wheel 26, i.e., in the contact area 28 between the welding wheel 26 and one of the parts to be welded 2. The material loss in the contact area 28 is a function of the material of the welding wheel 26 and the temperature of the contact area 28 when the welding machine 1 is in operation. At this time, it is understood that the contact area 28 forms the active surface of the welding wheel 26. Furthermore, the material loss around the welding wheel 26 tends to gradually decrease the diameter D of the welding wheel 26, as shown in Figure 3. To compensate for this material loss from the welding wheel 26 when the welding machine 1 is used, the welding machine is equipped with a third pressing component 24c for the welding wheel 26. The third pressing component 24c ensures contact between the welding wheel 26 and one of the raised edges of the parts to be welded, regardless of the diameter of the welding wheel 26. Therefore, it is understood that the third pressing component 24c allows for adjustment of the clearance between the welding wheel 26 and one of the parts to be welded, which is caused by circumferential wear of the welding wheel 26 when the welding machine 1 is in operation, and thus allows for the formation of a weld by the effective resistance of the parts to be welded.

[0058] As shown in the illustrated example of the present invention, the welding wheel 26 is positioned longitudinally on the welding machine 1 between one of the first pair of drive wheels 20a and one of the second pair of drive wheels 20b, which are arranged facing each other in the longitudinal direction L of the welding machine 1. Furthermore, the welding wheel is positioned in a plane R together with the first pair of drive wheels 20a and the second pair of drive wheels 20b, which are positioned between them.

[0059] Alternatively, according to an example not shown in the present invention, the welding wheel is positioned in the welding machine in a longitudinal and transverse plane different from at least one of the planes on which at least one of the driving wheels of the welding machine extends.

[0060] According to an illustrated example of the present invention, the welding machine 1 comprises a first welding wheel 26a and a second welding wheel 26b, depending on the features of the at least one welding wheel 26 described above. The first welding wheel 26a and the second welding wheel 26b face each other in the lateral direction T of the welding machine 1. In other words, the first welding wheel 26a and the second welding wheel 26b face each other so as to clamp the parts to be welded, in particular the two raised edges of two parts to be welded. More specifically, the first welding wheel 26a is positioned facing the first raised edge of the first part to be welded, and the second welding wheel 26b is positioned facing the second raised edge of the second part to be welded.

[0061] In this case, it is understood that the third pressing component 24c of the welding machine 1 is positioned between the first welding wheel 26a and the second welding wheel 26b so that the welding wheels 26a and 26b are reliably pressed against the raised edges of the parts to be welded. Thus, regardless of the material loss of the welding wheels 26a and 26b in use, a sealed weld is provided between the two parts to be welded, particularly their raised edges.

[0062] According to one feature of the present invention not shown, the welding machine comprises a system for cooling at least one of the welding wheels. More specifically, each of the first and second welding wheels is cooled by a welding machine cooling system which involves active cooling by circulating a fluid inside the welding wheel. This limits the heating of the welding wheel when welding the parts to be welded. Furthermore, the drive wheels of a second pair of drive wheels can be cooled by a cooling system similar to the welding wheels, and the second pair of drive wheels are positioned downstream of the welding wheels in the direction of travel of the welding machine, i.e., in contact with the weld bead formed by the welding wheels.

[0063] According to an example of the present invention shown in Figure 6, the welding machine 1 includes at least one component 30 for synchronizing the rotation of a first welding wheel 26a with the rotation of a second welding wheel 26b. In other words, the welding machine 1 includes a synchronization component 30 that enables the first welding wheel 26a and the second welding wheel 26b to rotate simultaneously and at the same rotational speed as the welding machine 1 moves. In other words, the synchronization component rotatably connects the first welding wheel 26a and the second welding wheel 26b, and the initial rotation is imparted by the movement of the machine and contact between at least one of the two welding wheels 26a, 26b.

[0064] However, the present invention described above should not be limited to the means and configurations described and illustrated exclusively, but is equally applicable to any equivalent means or configurations and any combination thereof.

Claims

1. A welding machine (1) configured to move along at least two parts to be welded (2, 2a, 2b), the welding machine (1) having at least one drive wheel (20) intended to move the welding machine (1) relative to the parts to be welded (2, 2a, 2b), at least one actuator (22) capable of rotating the drive wheel (20), and at least one welding wheel (26) capable of welding the parts to be welded (2, 2a, 2b) by rolling against at least one of the parts to be welded (2, 2a, 2b), wherein the welding wheel (26) rotates freely relative to the drive wheel (20), the welding machine (1) having at least two drive wheels (20) and two separate actuators (22), and each drive wheel (20) being driven by one of the actuators (22). The welding machine (1) is characterized by this.

2. The welding machine (1) according to claim 1, wherein the welding wheel (26) is rotated when the welding machine (1) moves by bringing the welding wheel (26) into contact with one of the parts to be welded (2, 2a, 2b).

3. One of the drive wheels (20) is rotated at a first rotational speed by one of the actuators (22), and the other drive wheel (20) is rotated at a second rotational speed by the other actuator (22), the first rotational speed and the second rotational speed being different from each other. The welding machine (1) according to claim 2.

4. The welding machine (1) according to any one of claims 1 to 2, wherein one of the drive wheels (20) is rotated at a speed determined by one of the actuators (22), and the other drive wheel (20) is controlled based on the torque of the other actuator (22).

5. The welding machine (1) according to any one of claims 1 to 3, wherein the welding wheel (26) is arranged on the welding machine (1) between one of the drive wheels (20) and the other drive wheel (20) in the longitudinal direction (L) of the welding machine (1).

6. The welding machine (1) according to any one of claims 1 to 3, comprising at least one part (24c) for pressing the at least one welding wheel (26) against one of the parts to be welded (2, 2a, 2b).

7. The welding machine (1) according to any one of claims 1 to 3, comprising a first welding wheel (26a) and a second welding wheel (26b) facing each other in the lateral direction (T) of the welding machine (1).

8. The welding machine (1) according to claim 7, wherein the first welding wheel (26a) and the second welding wheel (26b) rotate when the welding machine (1) moves, and the welding machine (1) comprises at least one part (30) for synchronizing the rotation of the first welding wheel (26a) with the rotation of the second welding wheel (26b).

9. The welding machine (1) according to claim 7, wherein the first welding wheel (26a) and the second welding wheel (26b) rotate at the same rotational speed when the welding machine (1) moves.

10. The welding machine (1) according to any one of claims 1 to 3, capable of welding at least two raised edge portions (4) of two parts to be welded (2, 2a, 2b) of a sealing film (6) forming part of a tank (8) for storing and / or transporting cryogenic products.

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