An automatic laser welding device for dissimilar metals on cathode steel rods in aluminum electrolysis cells.

Abstract

This invention discloses an automatic laser welding device for dissimilar metal cathode steel rods in aluminum electrolysis cells, belonging to the technical field of welding equipment. It includes a welding base and a welding mechanism. A first welding zone and a second welding zone are formed on opposite sides of the top of the welding base. A first pusher plate is provided in the first welding zone, and a driving mechanism is provided on one side of the first pusher plate. The welding mechanism is located between the first and second welding zones and includes a vertical guide rail. The vertical guide rail is annular with its central opening facing both the first and second welding zones. A welding slider is provided on one side of the vertical guide rail and slides along it. An electric push rod is provided on one side of the welding slider. The electric push rod has a movable rod that moves towards the annular center of the vertical guide rail. The end of the movable rod is equipped with a welding gun and a ranging element. This automatic welding device can improve the welding efficiency and quality of dissimilar metals.

Description

Technical Field

[0001] This invention relates to the field of welding equipment technology, and specifically to an automatic laser welding device for dissimilar metals, specifically a cathode steel rod for an aluminum electrolysis cell. Background Technology

[0002] The cathode steel rod in the aluminum electrolysis cell needs to be electrically connected to the aluminum busbar. Currently, the mainstream connection method is to set an explosive block between the cathode steel rod and the aluminum busbar, which achieves an indirect connection between the cathode steel rod and the aluminum busbar. However, the explosive block introduces additional resistance into the connection system, resulting in additional energy loss during the operation of the aluminum electrolysis cell. Since the cathode steel rod is usually made of low-carbon steel, while the aluminum busbar is made of aluminum alloy, directly connecting the cathode steel rod and the aluminum busbar using dissimilar metal welding technology can ensure the reliability of the conductive connection and reduce energy loss. Currently, dissimilar metal welding of cathode steel rods and aluminum busbars is usually carried out manually. However, manual welding is inefficient and brittle iron-aluminum intermetallic compounds are prone to form during the welding process, making welding difficult. It is necessary to precisely control the position of the molten pool during the welding process to ensure the strength of the connection between the cathode steel rod and the aluminum busbar after welding. Summary of the Invention

[0003] To address the technical deficiencies in the background art, this invention proposes an automatic laser welding device for dissimilar metals on cathode steel rods in aluminum electrolysis cells, which solves the aforementioned technical problems and meets practical needs. The specific technical solution is as follows: An automatic laser welding device for dissimilar metal cathode steel rods in an aluminum electrolysis cell includes a welding base and a welding mechanism. The top of the welding base forms a first welding area and a second welding area on opposite sides. A first pusher plate is provided on the side of the first welding area away from the second welding area. A driving mechanism is provided on one side of the first pusher plate to move the first pusher plate toward the second welding area. The welding mechanism is located between the first welding area and the second welding area. The welding mechanism includes: a vertical guide rail, which is circular with its central opening facing the first welding area and the second welding area respectively; a welding slider that slides along the vertical guide rail on one side; an electric push rod on one side of the welding slider; a movable rod that moves toward the circular center of the vertical guide rail; and a welding gun and a ranging element at the end of the movable rod.

[0004] As a further technical solution of the present invention, the driving mechanism includes: a driving motor, the driving end of the driving motor is provided with a pusher screw extending toward the second welding area, a pusher slider that slides along the top of the welding base is sleeved on the outside of the pusher screw, the center of the pusher slider has a threaded hole matching the pusher screw, and the side of the pusher slider abuts against the first pusher plate.

[0005] As a further technical solution of the present invention, a support plate is provided on the side of the first welding area away from the second welding area, and two push screws are provided, both of which are movably connected to the support plate. A push slider is sleeved on the outside of each push screw. A drive belt is wound around the outer side of both pusher screws, and each end of the two pusher screws is provided with a pulley that matches the drive belt.

[0006] As a further technical solution of the present invention, a pushing spring is provided between the first pushing plate and the support plate, and a pushing block is provided on one side of the pushing slider that abuts against the side of the first pushing plate near the second welding area.

[0007] As a further technical solution of the present invention, a second pusher plate and a support plate are provided on the side of the second welding area away from the first welding area, a driving mechanism for moving the second pusher plate toward the first welding area is provided on one side of the second pusher plate, and a pusher compression spring is provided between the second pusher plate and the support plate.

[0008] As a further technical solution of the present invention, the welding base is movably connected to sliding rollers in both the first welding area and the second welding area, and the sliding rollers rotate from the first welding area toward the second welding area or from the second welding area toward the first welding area.

[0009] As a further technical solution of the present invention, the second welding area is provided with two busbar baffles on the side near the welding mechanism, and a welding area located on the side of the welding mechanism is formed between the two busbar baffles.

[0010] As a further technical solution of the present invention, the welding base is provided with two first guide inclined plates in the first welding area, and a first guide channel is formed between the two first guide inclined plates. The width of the first guide channel gradually decreases on the side closer to the welding mechanism.

[0011] As a further technical solution of the present invention, the welding base is provided with two second guide inclined plates in the second welding area, and a second guide channel is formed between the two second guide inclined plates. The width of the second guide channel gradually decreases on the side closer to the welding mechanism.

[0012] The beneficial effects of this invention are as follows: This invention discloses an automatic welding device for dissimilar metal welding of cathode steel rods and aluminum busbars in an aluminum electrolysis cell. The cathode steel rod and aluminum busbar are placed in a first welding zone and a second welding zone, respectively, for welding. Under the pushing action of the pusher plate, the cathode steel rod and aluminum busbar abut against each other at the welding mechanism, thus positioning them at the welding position. The welding slider drives the welding gun to move along the vertical guide rail while welding at the welding position. Through the cooperation of the electric push rod and the distance measuring element, the movement path of the welding gun is adjusted from a circle to a rectangle, so that the welding gun can form a rectangular weld at the welding position between the cathode steel rod and the aluminum busbar, thereby firmly welding and fixing the cathode steel rod and the aluminum busbar. The automatic welding device of this invention can automatically weld dissimilar metals of cathode steel rods and aluminum busbars, improving welding efficiency while ensuring welding quality. Attached Figure Description

[0013] Figure 1 A schematic diagram of the structure of an automatic laser welding device for dissimilar metal cathode steel rods in an aluminum electrolysis cell. Figure 1 .

[0014] Figure 2 A schematic diagram of the structure of an automatic laser welding device for dissimilar metal cathode steel rods in an aluminum electrolysis cell. Figure 2 .

[0015] Figure 3 yes Figure 1 A partial schematic diagram of point A in the middle.

[0016] Wherein: 1-Welding base, 11-First welding area, 12-Second welding area, 13-First pusher plate, 14-Support plate, 15-Second pusher plate, 16-Sliding roller, 17-Busline baffle, 18-First guide plate, 19-Second guide plate, 2-Welding mechanism, 21-Vertical guide rail, 22-Welding slider, 23-Electric push rod, 24-Modular rod, 25-Welding gun, 26-Distance measuring element, 3-Drive mechanism, 31-Drive motor, 32-Pusher screw, 33-Pusher slider, 34-Transmission belt, 35-Pulley, 36-Pusher spring, 37-Pusher stop block. Detailed Implementation

[0017] The embodiments of the present invention will be described below with reference to the accompanying drawings and examples. The embodiments of the present invention are not limited to the following examples, and the present invention relates to the relevant necessary components in this technical field, which should be regarded as well-known technology in this technical field and can be known and mastered by those skilled in this technical field.

[0018] An automatic laser welding device for dissimilar metal cathode steel rods in an aluminum electrolysis cell includes a welding base 1 and a welding mechanism 2. A first welding area 11 and a second welding area 12 are formed on opposite sides of the top of the welding base 1. A first pusher plate 13 is provided on the side of the first welding area 11 away from the second welding area 12. A drive mechanism 3 is provided on one side of the first pusher plate 13 to move the first pusher plate 13 toward the second welding area 12. The welding mechanism 2 is located between the first welding area 11 and the second welding area 12. The welding mechanism 2 includes: a vertical guide rail 21, which is circular with its central opening facing the first welding area 11 and the second welding area 12 respectively. A welding slider 22 is provided on one side of the vertical guide rail 21 and slides along the vertical guide rail 21. An electric push rod 23 is provided on one side of the welding slider 22. The electric push rod 23 is provided with a movable rod 24 that moves toward the circular center of the vertical guide rail 21. A welding gun 25 and a distance measuring element 26 are provided at the end of the movable rod 24.

[0019] This invention discloses an automatic welding device for dissimilar metal welding of cathode steel rods and aluminum busbars in aluminum electrolysis cells. The device precisely positions the cathode steel rods and aluminum busbars during automatic welding, improving welding efficiency while ensuring smooth dissimilar metal welding. (Refer to...) Figure 1 , Figure 2 The automatic welding device mainly consists of a welding base 1, a welding mechanism 2, and a driving mechanism 3. The welding base 1 serves as the outer frame of the automatic welding device, and is used as the installation support structure for the automatic welding device and the structure for fixing the welding mechanism 2 and the driving mechanism 3. The top of the welding base 1 is provided with a first welding area 11 for placing the cathode steel rod and a second welding area 12 for placing the aluminum busbar. Since the cathode steel rod is usually small in size and the aluminum busbar is large in size, it has higher stability after being placed on the top of the welding base. The first pusher plate 13 is moved toward the second welding area 12 by the drive mechanism 3. During the movement of the first pusher plate 13, it will push the cathode steel rod toward the aluminum busbar until the cathode steel rod and the aluminum busbar come into contact. The position of contact between the two matches the position of the welding mechanism 2. The welding mechanism 2 welds the position of contact between the two, thereby realizing the dissimilar metal welding operation between the cathode steel rod and the aluminum busbar. Since both the cathode steel rod and the aluminum busbar have rectangular cross-sections, the contact surface at the connection point between them is usually also rectangular. Welding mechanism 2 needs to weld the cathode steel rod and the aluminum busbar along the edge of the rectangular contact surface, and the weld path formed after welding is rectangular. In welding mechanism 2, the welding gun 25 adopts a common laser welding gun, and the cathode steel rod and the aluminum busbar are laser welded by the welding gun 25. The vertical guide rail 21 and the welding slider 22 together form a common electric ring guide rail structure. The vertical guide rail 21 is equipped with a synchronous belt. The welding slider 22 is fixedly connected to the synchronous belt. The synchronous belt is driven by the motor to rotate cyclically, thereby driving the welding slider 22 to move along the vertical guide rail 21. The ranging element 26 adopts a common distance sensor, which is used to measure the distance between the welding gun 25 and the surface of the cathode steel rod. Reference Figure 1 , Figure 2 , Figure 3 During the welding process of the welding mechanism 2, the welding slider 22 moves along the vertical guide rail 21 and drives the welding gun 25 to move synchronously. If welding is performed directly at this time, the weld path formed by the welding gun 25 is circular, not the rectangular weld path required in practice. However, through the cooperation of the distance measuring element 26 and the electric push rod 23, the distance measuring element 26 will measure the distance between the welding gun 25 and the cathode steel rod in real time during the movement of the welding slider 22 and the welding gun 25, and set an appropriate value for the distance. When the distance between the welding gun 25 and the surface of the cathode steel rod changes during the movement, the movable rod 24 of the electric push rod 23 will extend and retract to keep the distance between the welding gun 25 and the surface of the cathode steel rod constant. That is, through the cooperation of the electric ring guide rail structure and the electric push rod 23, the movement path of the welding gun 25 is made rectangular, so that the welding gun 25 can weld a rectangular weld at the contact position between the cathode steel rod and the aluminum busbar, which meets the requirements for dissimilar metal welding of the cathode steel rod and the aluminum busbar. It should be noted that the end of the welding gun 25 that generates the welding laser beam is tilted toward the second welding area 12. So, during the dissimilar metal welding process of the welding mechanism 2, the laser beam generated by the welding gun 25 will act on the surface of the aluminum busbar, causing the aluminum alloy with a lower melting point to melt and form a molten pool. The aluminum alloy that is re-solidified after melting will connect the aluminum busbar and the cathode steel rod together.

[0020] As one of the preferred embodiments of the present invention, refer to Figure 1 , Figure 2 The drive mechanism 3 includes: a drive motor 31, the drive end of the drive motor 31 is provided with a pusher screw 32 extending toward the second welding area 12, the pusher screw 32 is sleeved on the outside of the pusher slider 33 that slides along the top of the welding base 1, the center of the pusher slider 33 is provided with a threaded hole matching the pusher screw 32, and the side of the pusher slider 33 abuts against the first pusher plate 13. The drive mechanism 3, in cooperation with the first pusher plate 13, can make the cathode steel rod move toward the aluminum busbar. When the drive motor 31 is working, it will cause the pusher screw 32 to rotate. The rotating pusher screw 32 meshes with the threaded hole of the pusher slider 33, causing the pusher slider 33 to move along the pusher screw 32. At the same time, it drives the first pusher plate 13 to move. During the movement of the first pusher plate 13, it will come into contact with the cathode steel rod and push the cathode steel rod toward the aluminum busbar.

[0021] As one of the preferred embodiments of the present invention, refer to Figure 1 , Figure 2 A support plate 14 is provided on the side of the first welding area 11 away from the second welding area 12. Two pusher screws 32 are provided and both are movably connected to the support plate 14. A pusher slider 33 is sleeved on the outside of each pusher screw 32. A transmission belt 34 is wound around the outside of the two pusher screws 32. A pulley 35 matching the transmission belt 34 is provided at the end of each of the two pusher screws 32. The support plate 14 is movably connected to the pusher screw 32 via bearings, allowing the pusher screw 32 to rotate smoothly and steadily. When the drive motor 31 directly drives one of the pusher screws 32 to rotate, the pusher screw 32 will drive the pulley 35 on its surface to rotate. The rotating pulley 35 will cause the transmission belt 34 to rotate synchronously and drive the pulley 35 on the surface of the other pusher screw 32 to rotate, thereby causing the two pusher screws 32 to rotate synchronously. The two synchronously rotating pusher screws 32 will cause the two pusher sliders 33 to move synchronously, so that the first pusher plate 13 and the two pusher sliders 33 have two points of force application. The two pusher sliders 33 are located at the two ends of the length direction of the first pusher plate 13, which can make the force on the first pusher plate 13 more balanced, so that the first pusher plate 13 can smoothly push the cathode steel rod to move.

[0022] As one of the preferred embodiments of the present invention, refer to Figure 1 , Figure 2A pusher spring 36 is provided between the first pusher plate 13 and the support plate 14. A pusher block 37 is provided on one side of the pusher slider 33, abutting against the side of the first pusher plate 13 near the second welding area 12. When the cathode steel rod contacts the aluminum busbar and during the welding process, the drive motor 31 needs to pause to prevent the first pusher plate 13 from continuously exerting a pushing force on the cathode steel rod. However, when the first pusher plate 13 pushes the cathode steel rod into contact with the aluminum busbar, the reaction force generated by the collision between the cathode steel rod and the aluminum busbar may cause them to separate. To ensure continuous contact between the cathode steel rod and the aluminum busbar, the first pusher plate 13 moves toward the cathode steel rod under the elastic force of the pusher spring 36, while the pusher slider 33 restricts the position of the first pusher plate 13 by the pusher stop 37. When the pusher slider 33 moves toward the second welding area 12, the pusher spring 36 continuously pushes the first pusher plate 13 to push the cathode steel rod through its elastic force. After the cathode steel rod contacts the aluminum busbar, the elastic force of the pusher spring 36 continues to act on the cathode steel rod, keeping the cathode steel rod in contact with the aluminum busbar.

[0023] As one of the preferred embodiments of the present invention, refer to Figure 1 , Figure 2 The second welding area 12 is provided with a second pusher plate 15 and a support plate 14 on the side away from the first welding area 11. A drive mechanism 3 is provided on one side of the second pusher plate 15 to move the second pusher plate 15 toward the first welding area 11. A pusher spring 36 is provided between the second pusher plate 15 and the support plate 14. The second pusher plate 15, in cooperation with the support plate 14, the pusher spring 36, and the drive mechanism 3, can push the aluminum busbar toward the cathode steel rod. The drive end of the drive motor 31 is provided with a pusher screw 32 extending toward the first welding area 11. A pusher slider 33 that slides along the top of the welding base 1 is sleeved on the outside of the pusher screw 32. A threaded hole matching the pusher screw 32 passes through the center of the pusher slider 33. A pusher stop 37 that abuts against the side of the second pusher plate 15 near the first welding area 11 is provided on one side of the pusher slider 33. The working principle of the second pusher plate 15 pushing the aluminum busbar is similar to the working principle of the first pusher plate 13 pushing the cathode steel rod, and will not be described in detail here. Furthermore, referring to Figure 1 , Figure 2Two busbar baffles 17 are provided on the side of the second welding area 12 near the welding mechanism 2. The two busbar baffles 17 form a welding area on the side of the welding mechanism 2. The second pusher plate 15 pushes the aluminum busbar toward the cathode steel rod under the elastic force of the pusher spring 36 until the aluminum busbar abuts against the busbar baffle 17. Since the cross-sectional size of the aluminum busbar on the welding position side is usually larger than that of the cathode steel rod, the aluminum busbar needs to be blocked by the busbar baffle 17 when positioning it to achieve the positioning of the aluminum busbar and prevent the aluminum busbar from intruding into the welding mechanism 2. The cathode steel rod passes through the welding mechanism 2 and abuts against the aluminum busbar in the welding area. The welding position where the aluminum busbar and the cathode steel rod abut against each other is in the welding area on the side of the welding mechanism 2. The welding mechanism 2 performs welding operation on the welding position by tilting the welding gun 25 toward the welding area. It should be noted that the elastic force generated by the pusher spring 36 between the second pusher plate 15 and the support plate 14 needs to be greater than the elastic force generated by the pusher spring 36 between the first pusher plate 13 and the support plate 14, so as to avoid the elastic force on the cathode steel rod side being greater than the elastic force on the aluminum busbar side, thereby keeping the aluminum busbar and the busbar baffle 17 in contact.

[0024] As one of the preferred embodiments of the present invention, refer to Figure 1 , Figure 2 The welding base 1 is movably connected to the sliding rollers 16 in both the first welding area 11 and the second welding area 12. The ends of the sliding rollers 16 are movably connected to the welding base 1 via shafts. The sliding rollers 16 rotate from the first welding area 11 toward the second welding area 12 or from the second welding area 12 toward the first welding area 11. The cathode steel rod and the aluminum busbar are both placed on the surface of the sliding rollers 16 for sliding. During the movement of the cathode steel rod and the aluminum busbar, the sliding rollers 16 will be driven to rotate to improve the smoothness of the movement.

[0025] As one of the preferred embodiments of the present invention, refer to Figure 1 , Figure 2 The welding base 1 is provided with two first guide inclined plates 18 in the first welding area 11, and a first guide channel is formed between the two first guide inclined plates 18. The width of the first guide channel gradually decreases on the side closer to the welding mechanism 2. The first guide channel formed between the two first guide inclined plates 18 can accurately enter the welding mechanism 2, ensuring that the cathode steel rod and the aluminum busbar can contact each other at the welding mechanism 2 and perform subsequent welding operations.

[0026] As one of the preferred embodiments of the present invention, refer to Figure 1 , Figure 2The welding base 1 is provided with two second guide plates 19 in the second welding area 12. A second guide channel is formed between the two second guide plates 19. The width of the second guide channel gradually decreases on the side closer to the welding mechanism 2. The second guide channel with a gradually decreasing width is formed between the two second guide plates 19. The width of the second guide channel is greater than the width of the first guide channel. This second guide channel can make the end of the aluminum busbar accurately approach the welding mechanism 2, ensuring that the cathode steel rod and the aluminum busbar can contact each other at the welding mechanism 2 and perform subsequent welding operations.

[0027] In summary, this invention discloses an automatic welding device for dissimilar metal welding of cathode steel rods and aluminum busbars in an aluminum electrolysis cell. The cathode steel rod and aluminum busbar are placed in the first welding zone 11 and the second welding zone 12, respectively, for welding operation. Under the pushing action of the pusher plate, the cathode steel rod and aluminum busbar abut against each other at the welding mechanism 2 and are positioned to be welded. The welding slider 22 drives the welding gun 25 to move along the vertical guide rail 21 while welding the position to be welded. Through the cooperation of the electric push rod 23 and the distance measuring element 26, the movement path of the welding gun 25 is adjusted from circular to rectangular, so that the welding gun 25 can form a rectangular weld at the position to be welded between the cathode steel rod and the aluminum busbar, thereby firmly welding and fixing the cathode steel rod and the aluminum busbar. The automatic welding device of this invention can automatically weld dissimilar metals of cathode steel rods and aluminum busbars, improving welding efficiency while ensuring welding quality.

[0028] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An automatic laser welding device for dissimilar metal cathode steel rods in an aluminum electrolysis cell, comprising a welding base (1) and a welding mechanism (2), characterized in that, The welding base (1) has a first welding area (11) and a second welding area (12) formed on opposite sides of its top. A first pusher plate (13) is provided on the side of the first welding area (11) away from the second welding area (12). A drive mechanism (3) is provided on one side of the first pusher plate (13) to move the first pusher plate (13) toward the second welding area (12). The welding mechanism (2) is located between the first welding area (11) and the second welding area (12). The welding mechanism (2) includes: a vertical guide rail (21), which is circular and has its central opening facing the first welding area (11) and the second welding area (12) respectively. A welding slider (22) is provided on one side of the vertical guide rail (21) and slides along the vertical guide rail (21). An electric push rod (23) is provided on one side of the welding slider (22). The electric push rod (23) is provided with a movable rod (24) that moves toward the circular center of the vertical guide rail (21). A welding gun (25) and a distance measuring element (26) are provided at the end of the movable rod (24).

2. The automatic laser welding device for dissimilar metals of cathode steel rods in aluminum electrolysis cells according to claim 1, characterized in that, The driving mechanism (3) includes a driving motor (31), the driving end of the driving motor (31) is provided with a pusher screw (32) extending toward the second welding area (12), the outside of the pusher screw (32) is provided with a pusher slider (33) that slides along the top of the welding base (1), the center of the pusher slider (33) is provided with a threaded hole that matches the pusher screw (32), and the side of the pusher slider (33) abuts against the first pusher plate (13).

3. The automatic laser welding device for dissimilar metal cathode steel rods in aluminum electrolysis cells according to claim 2, characterized in that, A support plate (14) is provided on the side of the first welding area (11) away from the second welding area (12). There are two push screws (32) and both are movably connected to the support plate (14). A push slider (33) is sleeved on the outside of each push screw (32). A drive belt (34) is wound around the outer side of both pusher screws (32), and each end of the two pusher screws (32) is provided with a pulley (35) that matches the drive belt (34).

4. The automatic laser welding device for dissimilar metal cathode steel rods in aluminum electrolysis cells according to claim 3, characterized in that, A pusher spring (36) is provided between the first pusher plate (13) and the support plate (14), and a pusher block (37) is provided on one side of the pusher slider (33) to abut against the side of the first pusher plate (13) near the second welding area (12).

5. The automatic laser welding device for dissimilar metal cathode steel rods in aluminum electrolysis cells according to claim 1, characterized in that, The second welding area (12) is provided with a second pusher plate (15) and a support plate (14) on the side away from the first welding area (11). A drive mechanism (3) is provided on one side of the second pusher plate (15) to move the second pusher plate (15) toward the first welding area (11). A pusher spring (36) is provided between the second pusher plate (15) and the support plate (14).

6. The automatic laser welding device for dissimilar metal cathode steel rods in aluminum electrolysis cells according to claim 1, characterized in that, The welding base (1) is movably connected with sliding rollers (16) in both the first welding area (11) and the second welding area (12). The sliding rollers (16) rotate from the first welding area (11) toward the second welding area (12) or from the second welding area (12) toward the first welding area (11).

7. The automatic laser welding device for dissimilar metals of cathode steel rods in aluminum electrolysis cells according to claim 1, characterized in that, The second welding area (12) is provided with two busbar baffles (17) on the side near the welding mechanism (2), and a welding area is formed between the two busbar baffles (17) on the side of the welding mechanism (2).

8. The automatic laser welding device for dissimilar metal cathode steel rods in aluminum electrolysis cells according to claim 1, characterized in that, The welding base (1) has two first guide plates (18) in the first welding area (11), and a first guide channel is formed between the two first guide plates (18). The width of the first guide channel gradually decreases on the side closer to the welding mechanism (2).

9. The automatic laser welding device for dissimilar metal cathode steel rods in aluminum electrolysis cells according to claim 1, characterized in that, The welding base (1) has two second guide plates (19) in the second welding area (12), and a second guide channel is formed between the two second guide plates (19). The width of the second guide channel gradually decreases on the side closer to the welding mechanism (2).

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