NL2024484B1

NL2024484B1 - Welding torch assembly

Info

Publication number: NL2024484B1
Application number: NL2024484A
Authority: NL
Inventors: Wilhelmus Elisabeth Lafleur William
Original assignee: Sif Netherlands B V
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2021-09-02

Abstract

The invention provides A welding torch assembly for a welding device, the welding torch assembly comprising a frame, a proximal part, coupled to the frame, comprising an electrode wire feeder, a distal part, comprising a welding torch holder, the welding 5 torch holder conﬁgured to hold a welding torch to the distal part, a hinge for moveably coupling the distal part to the proximal part, and an actuator coupled to the distal part and the proximal part conﬁgured to move the distal part of the welding torch assembly with respect to the proximal part, wherein the electrode wire feeder is conﬁgured to feed two electrode wires to the welding torch through the welding torch holder, and the 10 welding torch is conﬁgured to weld a groove, connecting two metal sheets, when a current is applied through the two electrode wires fed to the welding torch.

Description

Welding torch assembly Field of the invention

[0001] The present invention relates to a welding torch assembly for a welding device. Background art

[0002] Known welding torch assembly includes a welding torch, into which two wires are fed through to form two electrodes that are used to generate a welding arc for the deposition of molten metal in a narrow gap between two metal parts, in order to join the metal parts together.

[0003] The welding torch assembly can be used for welding large cylindrical, conical or tubular structures, such as shells for assembling piles. The piles can be used in, for example, oil and gas platforms or wind turbines.

[0004] A shell can be formed by rolling a steel plate into a curved shape and welding the ends of the rolled plate together to form a cylindrical or conical shape. Typically, the diameter of the shell is 8 meters (m) and the length of the shell is between 2 to 4 m, and the thickness of the steel plates of the shell is typically between 60 and 120 millimetres (mm). By adjusting the rolling, it is possible to weld the steel plates to form shells of varying sizes.

[0005] In order to produce a weld between the steel plates, each plate is fabricated with grooves on the connecting side of the plate. The grooves allow the welding torch to gradually deposit welding material along the thickness of the plate, welding the ends of the rolled plate together to form the shell.

[0006] In order to obtain welds of good quality, the welding torch must be positioned close to the welding material deposited at the inside of the groove. For thick plates, the groove is also deep, wherein the weld material deposited in the valley of the groove. The groove opening must be sufficiently large to accommodate the welding torch in order for the welding torch to be positioned close to the deposited welding material inside the groove. Since the groove must be able to accommodate the weld torch, more welding must be performed — using more weld material — in the groove, which may lead to inaccurate welding resulting in a low quality weld.

[0007] Such a welding device is known from EP3505288.

Summary of the invention °

[0008] It 1s an object of the invention to provide a welding torch assembly for a welding device that enables more efficient welding of the shells. This object is achieved by the welding torch in accordance with the present invention, the welding torch comprising a frame, a proximal part, coupled to the frame, comprising an electrode wire feeder, a distal part, comprising a welding torch holder, the welding torch holder configured to hold a welding torch to the distal part, a hinge for moveably coupling the distal part to the proximal part; and an actuator coupled to the distal part and the proximal part configured to move the distal part of the welding torch assembly with respect to the proximal part, wherein the electrode wire feeder is configured to feed two electrode wires to the welding torch through the welding torch holder, and the welding torch is configured to weld a groove, connecting two metal sheets, when a current is applied through the two electrode wires fed to the welding torch. In this assembly, the welding torch in the welding torch assembly is movable, allowing for a more precise orientation within the groove and reduction of material for filling the groove weld/seal. Furthermore, the distal end can be more compact may be configured to perform movement in smaller increments.

[0009] In a further embodiment, the proximal part comprises a connecting bar and the distal part comprises an axial thread, wherein the hinge comprises a barrel section mounted on the connecting bar and a pivot configured to rotate the axial thread. This arrangement allows the distal part to move with respect to the proximal part, which is fixed onto the frame of the welding torch assembly. This assembly allows the welding torch, in the distal part of the welding torch assembly, to freely move inside the groove, allowing for a more improved manoeuvrability of the welding torch between the two metal plates. This allows for a more accurate milling along the thickness of the metal plates.

[0010] In a further embodiment, the torch assembly further comprise a controller arranged to control the actuator to move the distal part in the groove between the two metal sheets. This arrangement allows welding torches to be able to be electronically controlled. Furthermore, this allows the controller to set the incremental movement of the welding torches in the groove, allowing for further fine-tuning of the movement of the welding torches.

[0011] In an advantageous embodiment, the welding torch is further configure to hold a second welding torch to the distal part, the electrode wire feeder is further configured to feed two electrode wires to the second welding torch through the welding torch holder,

and the second welding torch is configured to oy the groove, connecting the two metal sheets, when a current is applied through the two electrode wires of the second welding torch. By being able to weld two separate locations simultaneously, it is possible to mill more efficiently inside the groove by, for example, being able to apply two welding torches along the same melting path, or welding at two separate layers inside the groove.

[0012] In a further embodiment, the welding torch holder comprises a block-like body for positioning the first and the second welding torches apart by a predetermined distance. By comprising of a block-like structure, it is possible to customize position — and thereby the spacing — of the two welding torches through the insertion or replacement of blocks, without the need for manufacturing different welding torch holders for holding the welding torches in different positions.

[0013] In an advantageous embodiment, the welding torch holder is further configured to hold a welding powder distributor, configured to deposit welding powder, between the first and second welding torches. In this assembly, if the first welding torch exhausts the molten metal supply available in the groove, the welding powder distributor is able to deposit welding powder between the welding torches and replenishing the molten metal supply in the groove and allowing the second welding torch to maintain its welding operation.In a further embodiment, the welding powder distributor is connected to a powder container configured to transport weld powder to the welding powder distributor.

This allows for the weld powder to be supplied to the welding torches without the need to manually introduce additional weld powder into the melting path in the groove.

[0014] In a further embodiment, the welding powder distributor is connected to a powder container configured to transport weld powder to the welding powder distributor. In this assembly, the welding powder distributor is connected to a powder container to supply the groove with weld powder.

[0015] In a further embodiment, the first and the second welding torches are coupled onto the welding torch holder at different angles. This assembly allows for different configurations of welding operations to be performed by the welding torches, while maintaining a melting path.

[0016] In a further embodiment, the first and the second welding torches are aligned in series. This assembly allows for welding along the thickness of the plate while maintaining a melting path.

[0017] In a further embodiment, wherein an alternating current, AC, is applied to the first welding torch, and a direct current, DC is applied to the second welding torch. This assembly allows for one of the welding torches to perform DC welding whilst the other welding torch to perform AC welding to avoid mutual forces on the welding torches of the magnetic fields due to the DC currents. This assembly in the welding torch holder prevents unwanted short circuiting or electrical arcing between the welding torches.

[0018] In a further embodiment, the welding torch holder, the first welding torch and the second welding torch is partially covered with at least one non-magnetic insulation panel. This assembly prevents unwanted short circuiting and arcing of the welding torch holder.

[0019] In a further embodiment, the welding torch comprises a block-like body provided with two-parallel channels in a longitudinal direction of the block-like body for guiding the electrode wires through the block-like body. This assembly of the welding torch prevents unwanted short circuiting and/or arcing inside the welding torch by keeping the electrode wires apart from another until they are required for the welding process.

[0020] The invention further provides a welding device comprising a welding torch assembly according to any of the claims 1 to 12. Brief description of the drawings

[0021] The present invention will be discussed in more detail below, with reference to the attached drawings, in which:

[0022] Fig. 1 depicts a welding device.

[0023] Fig. 2 depicts a cross section of a partially welded joint.

[0024] Fig. 3 depicts a cross section of a welding torch.

[0025] Fig. 4 depicts the welding torch assembly.

[0026] Fig. 5a depicts a side view of the hinge connecting the proximal and distal parts of the welding torch assembly.

[0027] Fig 5b depicts a front view of the hinge connecting the proximal and distal parts of the welding torch assembly.

[0028] Fig. 6a depicts a front view of the angled welding torches.

[0029] Fig. 6¢ depicts a side view of the angled welding torches.

[0030] Fig. 7 depicts the welding powder distributor for the welding torch assembly.

[0031] Fig. 8 depicts a non-magnetic insulation material 900 on the surface of the distal part 100 of the welding torch assembly. Description of embodiments

[0032] The welding torch assembly is described with reference to Figures 1 — 8. In the figures like reference signs indicate like parts.

[0033] The welding torch assembly can be so for welding large cylindrical, conical or tubular structures, such as shells for assembling piles for wind generators and for off- shore platforms. Typically, the diameter of the shell is 8 meters (m) and the length of the shell is between 2 to 4 m, and the thickness of the steel plates of the shell is typically between 60 and 120 millimetres (mm).

[0034] A shell can be formed by rolling a steel plate into a curved shape and welding the ends of the rolled plate together to form a cylindrical or conical shape. By adjusting the rolling, it 1s possible to weld the steel plates to form shells of varying sizes.

[0035] After the shell formed, two grooves are milled on the side of the steel plate that will be welded — one groove on the inside of the shell, and one groove on the outside of the shell. Firstly, the welding is performed on the groove inside of the shell. Thereafter, the welding is performed on the groove outside of the shell using the welding device as described with reference to Figure 1.

[0036] Figure 1 shows an embodiment of a welding device 1 for welding a groove on a shell 14. The welding device 1 comprises a frame 2, a welding torch assembly 10, and electrode wire turntables for providing electrode wires 5, 6 to the welding torch assembly

10. The welding device 1 further comprises a transport device 15 for moving the shell

14.

[0037] The welding torch assembly 10 comprises an electrode wire feeder that receives the electrode wires 5, 6 from the electrode wire turntables and a welding torch holder. The electrode wires are then fed through the welding torch holder, to the welding torch

9. The welding torch is mounted onto the welding torch holder.

[0038] The welding torch holder is configured to hold at least one welding torch 9. When more welding torches are attached to the welding torch holder, a body may be placed between the welding torches to keep the torches apart. Furthermore, the welding torch holder may be arranged to hold the welding torches at different angles.

[0039] Furthermore, the welding device is provided with a controller 310. The controller 310 is arranged to feed the electrode wires 5, 6 from the electrode wire turntables to the electrode wire feeders in the welding torch assembly 10 at a transport speed of the electrode wires is between 2 — 10 m/min, preferably 3 — 6 m/min, more preferably about 4 m/min.

[0040] Furthermore, the welding torch assembly is provided with power sources (not shown) which can be programmed to provide an alternating current (AC), a direct current (DC) or both currents through the welding torches and the shell, where the shell acts as the ground to the two currents. The welding currents can range between 600 to 900A for DC welding and in the range between 700 to 950 A for AC welding. In order to prevent unwanted mutual forces (e.g. short circuits), when an AC is applied to a first welding torch, a DC current is applied to any other welding torches in the welding torch holder.

[0041] In general, the welding of the shell 14 is performed such that the grooves are asymmetrically positioned with respect to the centre of the steel plate in such a way that the groove at the inner side is less deep than the groove at the outer side of the shell.

[0042] Figure 2 shows schematically a cross-section of a partly welded joint 20 in the shell 14. Figure 2 shows a first welded groove 22 and the second non welded groove or gap 13. In this embodiment, the thickness of the steel plate of the shell is 20mm — 120mm, preferably 40 — 100mm, most preferably 80mm and the first welded groove 22 has a depth of 10mm — 30mm, preferably 20mm and the second non-welded groove 13 has a depth of 50 — 100mm, preferably 60 — 80mm, most preferably 65mm. The joints can be any type of joint, for example, a V-joint or a U-joint. The inner joint may be a V joint, whereas the outer joint may be a U-joint. Both joints can be positioned on the same edge and thereby forming, for example, a single V, single U joint type.

[0043] The welding process is first performed on the inner surface of the steel plate. The welding of the two edges of the inner surface is performed at the first weld groove 22.

[0044] Weld material is deposited at one edge of the valley of the weld groove 22. A welding torch then applies an electric current across the weld material in order to generate a weld layer. Then, weld material is deposited at the opposite edge of the groove, and the welding torch generates a new weld layer. This new weld layer overlaps with the previously generated weld layer. This process is repeated until the groove is filled with stacked overlapping weld layers 24.

[0045] The second welding process is performed on the second weld groove 13. In order tor the weld torch to fit inside the weld groove 13, the weld groove must be angled such that the side walls of the groove 13 converges to a trough at the bottom of the groove. For example in the second (non-)welded groove 13 the angle between a side wall and the normal on the plate is for example 4° and the radius R of the bottom part of the second non-welded groove or gap 13 is 7 mm. In another example the angle between the side wall and the normal on the plate is 6.5° and the radius R of the bottom part of the second non-welded groove or gap 13 is 8 mm.

[0046] In order to weld the gap 13 of the joint, the welding torches 11, 12 should initially be positioned close to the bottom in the gap 13.

[0047] Similarly to the first welding process, welding is performed by welding layers of electrode material on top of each other. For applying the subsequent layers the welding torches are moved upwards out of the groove 13.. The small dimension of the welding torch enables a smaller gap than conventionally is used. So, less metal should be milled away to form the gap 13 in the plate or shell. The welding torches according to this description can be advantageously applied in the field of narrow-gap welding.

[0048] A further advantage is that the reduced gap dimension can provide a reduction in design thickness of the wall of the shell, to obtain a shell having an equal strength compared to the strength of a shell welded by a conventional welding torch.

[0049] Figure. 3 shows schematically a cross-section of the welding torch 9 that can be applied in the welding device. Figure 3 shows one of two elongated parts 30 forming a block-like body provided with two parallel channels 31, 32 in a longitudinal direction. Furthermore, the elongated part is provided with the parallel grooves in the longitudinal direction such that when the elongated first and second parts are connected the channels 31, 32 are formed. The channels 31, 32 are configured to guide the electrode wires 5, 6 through the block-like body. Each channel has a first part 33, 34 at the entry side 35 and a second part 36, 37 at the outlet side 38. The second parts 36, 37 of the channels 31, 32 has a slightly smaller diameter than the diameter of the first parts 33, 34 of the channels 31, 32. The diameter of the second part 35, 36 of the channel 31, 32 is such that it tightly fits around the electrode wires 5, 6 for forming an electrical contact for conducting an electric welding current to the electrode wires 5, 6.

[0050] Figure. 4 shows the welding torch assembly 10 of Figure. 1. The welding torch assembly further comprises a frame 2, a proximal part 100, a distal part 200, and an actuator 300 connected to the proximal and distal parts. The proximal part 100 is movably coupled to the distal part 200 by a hinge 402. In a further embodiment, the proximal and distal parts may be connected by additional hinges 403. The proximal part 200 is coupled to the frame 2, and comprises an electrode wire feeder 210, 220 that receives the electrode wires 5, 6 from the electrode wire turntables. The electrode wires 5, 6 are then fed through to the distal part 100 of the welding torch assembly 10. The electrode wires are then fed through the welding torch holder 110 in the distal part 100, to the welding torch 9, 90. Furthermore, the distal part comprises a welding torch holder

110. The welding torch is held onto the distal part by the welding torch holder 110.

[0051] In order to accommodate at least one welding torch to the distal part 100, the welding torch holder 110 comprises blocks 111 and 112. By comprising of a block-like structure, it is possible to customize position We the two welding torches through the insertion or replacement of blocks 111, 112, without the need for manufacturing different welding torch holders for holding the welding torches in different positions.

[0052] An actuator 300, is connected to the proximal and distal parts of the welding torch assembly through a connection rod 500. The connection rod 500 is fixed at both ends, where one end is fixed to the proximal part 200 and the other end is connected to the distal part 100. When the actuator 300 is in operation, the actuator 300 moves the connection rod 500. As the distal and proximal parts are coupled to the connection rod 500, and the proximal part is coupled to the frame, the movement of the connection rod 500 displaces the distal part 100, thereby moving the distal part 100 of the welding torch assembly. The hinges 402, 403 coupled to the distal part 100 allows the actuator 300 to rotationally displace the distal part 100, i.e. the distal part 100 rotates due to the operation of the actuator 300. The actuator 300 may further be connected to a controller configured to control the actuator.

[0053] The coupling between the distal part 100 and the proximal part 200 is done by using the hinge 402 or a rotating joint. This allows only the distal part 100 to move independently from the proximal part 100. The hinge 402 can be fixed onto the distal part 100 using the axial thread 400, but can also be fixed onto the proximal part 200 using a connecting bar 401. The hinge is coupled to at least one side of the distal part 100.

Preferably, two hinges 402, 403 are used, fixed at opposite sides of the distal part 100, for rotational stability between the proximal and distal parts. The hinges 402, 403 at the distal part 100 are connected to the connecting bar 401 from the proximal part 200.

[0054] Figure 5 shows the hinge 402 of Figure 4. The Figure Sa shows the side view of the hinge system, with respect to the surface of the welding torch assembly, and Figure 5b shows the front view of the hinge system. The hinge 402 comprises a barrel section mounted on the connecting bar 401 of the proximal part 200. The hinge 402 comprises an opening, or a pivot, to allow the axial thread 400, connected to the distal part 100, to freely rotate around the pivot. Preferably, the axial thread is cylindrical such that the thread can be easily rotated around its axis to move the distal part 100.

[0055] The pivot of the hinge 402 may be an opening for the axial thread 400 to rotate in, or may be configured to restrict the rotation of the axial thread 400 such that the rotation is only performed incrementally. Furthermore, the rotation may be controlled by the actuator 300.

[0056] In another embodiment of the present fvention, the hinges can be positioned between the distal part and the proximal part. This has the advantage of maintaining the width, as adding hinges at the sides of the distal part results in a wider distal part. The hinges, however, must be positioned in a manner where it does not impede the supply of electrode wires to the welding torch.

[0057] The rotational motion of the distal part is transverse to the direction of the groove. This allows the distal part to move from side wall to side wall along the groove during the welding process.

[0058] In another embodiment, more than one hinge is used to stabilize the motion of the distal part in the groove. For example, the intervals that the hinge is able to rotate is finer, or more hinges can be used to stabilize and reduce the increment intervals of rotation. This allows for a finer positioning of the welding torch, resulting in an accurate placement of the weld inside the groove.

[0059] Furthermore, when the welding torch holder 110 comprises of more than one welding torch, 9, 90 both torches at the distal part may be rotationally movable with respect to the proximal part as shown in Figure 4. Furthermore, the welding torch assembly may be configured to independently rotate the two welding torches by using separate hinges.

[0060] The controller 310, as shown in Figure 1, is arranged to control the actuator 300 to move the distal part of the welding torch inside the groove through in the sidewall. By only moving the distal part, and not moving the remaining components of the welding torch assembly, the welding torches may be moved at smaller and finer increments. This may result in an increased accuracy in the melt paths in the grooves due to the better positioning of the welding torch inside the groove.

[0061] Another advantageous effect of the present invention is that, due to fewer components being in motion during the operation of the welding torch assembly, there is less wear and tear on the equipment. Since the only moving component of the welding torch assembly is the distal part, only the distal part may be inspected during maintenance, thereby reducing the costs of the overall operation.

[0062] Another advantageous effect of the present invention is that the non-moving components of the welding assembly 2, such as the proximal part 200, can perform checks (such as diagnostic checks) while still in operation. Previously, the proximal part was also moving, making the checking of the components of the proximal part to also be in motion. This may lead to inaccurate diagnostic checks of said components.

[0063] In an embodiment of the present invention the welding torch assembly comprises a second welding torch 90. The second welding torch 90 is configured to weld, using weld material in the groove, at the same time the first welding torch 9 is welding in the groove. The first and second welding torches may be configured to weld the same melting path, or separate melting paths, and produce separate stacked layers. Using a second welding torch greatly reduces the time taken to weld the grooves between the steel plates.

[0064] In Figure 6a and 6b, the two welding torches may be orientated at a fixed angle apart from each other in the distal part 100 of the welding torch assembly 2 in Figure 4. This assembly allows for different configurations of welding operations to be performed by the welding torches, while maintaining a melting path.

[0065] Figure 6a shows a welding torch holder comprising two welding torches 9, 90 at different angles. The wire feeding units 601, 602 on the distal part 100 feed the wires supplied from the wire feeder in the proximal part 200. As shown in Figure 3, the channels inside the welding torches feed the wires to the welding area. In addition to the welding torches 9, 90, the wire feeding units 601, 602 may also be at an angle to each other. This allows for the wires, being fed to the welding torches, to run in a linear path (at an angle) in the distal part 100. The wires will be angled in the space between the distal part and the proximal part. When the two welding torches are angled towards one another, the paths of the electrode wires intersect at an angle theta (9) as shown in Figure 6a.

[0066] Figure 6b shows a side view of Figure 6a. According to an embodiment of the present invention, not only are the welding torches 9, 90 at an angle with respect to the face of the welding torch holder, but also at an angle with respect to the vertical axis of the welding torch holder. This allows for two separate welding areas inside the groove.

[0067] In an embodiment of the present invention, the two welding torches in the welding torch holder may be orientated in series, i.e. one torch behind the other. This allows for both welding torches to weld the same electrode wire in separate stages. As the two weld torches are aligned and welding the same electrode wire, a problem arises where the first weld torch expends the weld powder first, leaving the second welding material with little to no weld powder.

[0068] Figure 7 shows an embodiment of the present invention where the weld torch assembly comprises a weld powder distributor 700 placed between the two welding torches 9, 90 in the distal part 100, configured to distribute weld powder between the first and second weld torches. By depositing ditional weld powder, the second weld torch is able to sufficiently weld the electrode wire.

[0069] The weld powder distributor 700 is connected to a powder container 702 via a weld powder transporter 701 that is configured to transport weld powder to the welding powder distributor.

[0070] Figure 8 shows the distal part 100 of the welding torch assembly wherein the welding torch holder, the first welding torch and the second welding torch is partially covered with at least one non-magnetic insulation material 900. Due to the large currents that can be fed to the welding torches, it is necessary to prevent a short-circuiting between the first and second welding torches during the operation of the welding torch assembly. This is overcome by introducing non-magnetic insulation material on the surfaces of the distal part of the welding torch assembly where such mutual forces may arise. The non-magnetic insulation material may comprise of more than one piece.

[0071] The method of operation of the welding torch assembly is described below using Figures 1 - 8 as reference.

[0072] Upon placement of the rolled steel shell 14 on the transport device 15, the welding torch assembly is configured to position the welding torch assembly comprising the distal part in the groove between the edges of the shell. The shell is connected to a grounding terminal. The electrode wire feeders supply the welding torch assembly with electrode wires. The electrode wires pass through the proximal part of the welding torch assembly which is fixed onto the frame 1 to the distal part of the welding torch assembly. Power sources connected to the welding torches apply a current to the welding torch to create a melting path of the electrode wires, resulting in a weld layer within the groove. The distal part is then repositioned to another region of the groove, and performs a weld process to produce a layer that is stacked (and overlaps) above the previous layer.

[0073] When two welding torches are present in the welding torch assembly, both torches may perform welding on the same electrode wire (melting path). A welding powder distributor is placed to replenish the weld powder inside the groove for the second welding torch, as the welding torch travels along the groove, along the melting path of the weld.

[0074] When both torches are configured to be at different angles, the welding process is performed on two separate electrode wires and generate two melt paths, resulting in a simultaneously overlapping and stacked layers.

[0075] In the description of the figures, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the scope of the invention as summarized in the attached claims.

[0076] In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

Conclusions

1. Welding torch assembly for a welding device, wherein the welding torch assembly comprises: - a frame; - a proximal portion coupled to the frame, comprising an electrode wire feeder, - a distal portion, comprising a welding torch holder, the welding torch holder being configured to hold a welding torch to the distal portion, - a hinge for movably coupling from the distal portion to the proximal portion; and an actuator coupled to the distal portion and the proximal portion and configured to move the distal portion of the welding torch assembly relative to the proximal portion, the electrode wire feeder being configured to feed two electrode leads to the welding torch through the welding torch holder, and the welding torch is configured to weld a groove connecting two metal plates when a current is applied through the two electrode wires supplied to the welding torch.

The welding torch of claim 1, wherein the proximal portion includes a connecting rod and the distal portion includes an axial thread, the hinge comprising: a barrel section mounted on the connecting rod and a pivot pin configured to rotate the axial threads.

The welding torch assembly of any preceding claim, wherein the welding assembly further comprises a control unit adapted to control the actuator to move the distal portion through the two metal plates in the groove.

The welding torch assembly of any preceding claim, wherein the welding torch is further configured to hold a second welding torch to the distal portion, the electrode wire feeder being further configured to supply two electrode wires to the second welding torch through the welding torch holder and the second welding torch is configured to weld the groove connecting the two metal plates when a current is applied through the two electrode wires of the second welding torch.

A welding torch assembly according to claim 4, wherein the welding torch holder comprises a block-shaped body for positioning the first and second welding torches at a predetermined distance from each other.

The welding torch assembly of claims 4 or 5, wherein the welding torch holder is further configured to hold a welding powder distributor configured to apply welding powder through the first and second welding torches.

The welding torch assembly of claim 6, wherein the welding powder distributor is connected to a powder reservoir configured to transport welding powder to the welding powder distributor.

A welding torch assembly according to any one of claims 4 to 7, wherein the first and second welding torches are coupled to the welding torch holder at different angles.

The welding torch assembly of any one of claims 4 to 8, wherein the first and second welding torches are aligned in series.

The welding torch assembly of any one of claims 4 to 9, wherein an alternating current, AC, is applied to the first welding torch, and a direct current, DC, is applied to the second welding torch.

A welding torch assembly according to any one of claims 4 to 10, wherein the welding torch holder, the first welding torch and the second welding torch are partially covered with at least one non-magnetic insulation panel.

A welding torch assembly according to any one of the preceding claims, wherein the welding torch comprises a block-like body provided with two parallel channels in a longitudinal direction of the block-like body for guiding the electrode wires through the block-shaped body.

A welding device comprising a welding torch assembly according to any one of claims 1 - 12.

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