Anti-deviation welding device for laser welding of aluminum row on battery core

Abstract

The invention relates to the technical field of power battery manufacturing, in particular to a battery cell aluminum row laser welding device capable of preventing welding deviation, which comprises a workbench, support frames are fixedly connected to the front and rear sides of the left and right sides of the top of the workbench, and fixing parts are arranged on the inner sides of the support frames; the fixing part comprises a first supporting plate, sliding blocks are fixedly connected to the front side and the rear side of the left side and the right side of the first supporting plate, and the frame wall of the supporting frame is slidably connected with the surfaces of the sliding blocks. According to the invention, a workpiece self-weight triggering mechanism is adopted, so that an electric or pneumatic power source required by a traditional clamping device is completely omitted, the energy consumption is reduced, real green production is realized, a bidirectional screw rod is matched with a synchronous belt for transmission to ensure the repeated positioning precision, crossed net-shaped anti-slip lines provide stable clamping force, the welding deviation rate is reduced, and the welding quality is improved. And the innovative cam-scraper mechanism automatically completes cleaning of the supporting surface in each operation cycle, so that the cleaning efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery manufacturing, and specifically relates to a device for laser welding aluminum bars of battery cores to prevent welding deviation. Background Art

[0002] In the field of power battery manufacturing, the laser welding process of aluminum bars has long faced two major technical problems: Firstly, it is difficult to ensure the welding positioning accuracy. Traditional clamping devices mostly use pneumatic or electric drives, which have problems such as uneven clamping force and positioning deviation, resulting in a welding qualification rate of only about 95%. Secondly, the problem of welding slag pollution is prominent. Existing equipment lacks an effective automatic cleaning function and requires frequent shutdowns for manual cleaning, seriously affecting production efficiency. Currently, welding equipment on the market generally has disadvantages such as high energy consumption, frequent maintenance, and a lot of manual intervention, and cannot meet the requirements of the new energy industry for efficient, precise, and automated production. Summary of the Invention

[0003] Therefore, the present invention provides a device for laser welding aluminum bars of battery cores to prevent welding deviation to solve the above problems.

[0004] The present invention provides the following technical solution: A device for laser welding aluminum bars of battery cores to prevent welding deviation, including a workbench. Both the front and back sides of the left and right sides of the top of the workbench are fixedly connected with support frames, and a fixing component is arranged inside the support frames; The fixing component includes a first support plate. Both the front and back sides of the left and right sides of the first support plate are fixedly connected with sliders, and the frame walls of the support frames are slidably connected with the surfaces of the sliders. Both the left and right sides of the bottom of the workbench are fixedly connected with second support plates. A friction-reducing coating is provided on the contact surface between the sliders and the support frames, and the friction-reducing coating is made of polytetrafluoroethylene material.

[0005] As a preferred solution of the present invention, a bidirectional lead screw is rotatably connected to the inner wall of the second support plate. Threaded sleeves are sleeved on both the left and right sides of the surface of the bidirectional lead screw with matching plates. The surface of the matching plate is slidably connected with a moving plate. A chute is opened at the bottom of the moving plate, and the surface of the chute wall is slidably connected with the surface of the matching plate. A spring is fixedly connected to the top of the matching plate, and the top of the spring is fixedly connected to the top inside the moving plate. A first limiting plate is fixedly connected to the outside of the moving plate, and a third support plate is fixedly connected to the left side of the bottom of the workbench.

[0006] As a preferred solution of the present invention, the number of the moving plates is two, and the two moving plates are symmetrically distributed left and right. A fixing plate is fixedly connected to the inside of the moving plate, and an anti-slip pattern is provided on the clamping surface of the fixing plate. The anti-slip pattern is a cross-shaped network structure.

[0007] As a preferred embodiment of the present invention, a first toothed plate is fixedly connected to the left side of the first support plate, a first rotating rod is fixedly connected to the left end of the bidirectional lead screw, a second rotating rod is rotatably connected to the inner wall of the third support plate, synchronous wheels are fixedly connected to the left ends of the second rotating rod and the first rotating rod, a synchronous belt is sleeved on the surface of the synchronous wheels, the synchronous belt is a polyurethane synchronous belt, and a wear-resistant rubber layer is provided on the tooth surface of the synchronous belt.

[0008] As a preferred embodiment of the present invention, a first gear is fixedly connected to the right end of the second rotating rod, and the first gear meshes with the first toothed plate.

[0009] As a preferred embodiment of the present invention, a first connecting plate is fixedly connected to the back surface of the first support plate, a second limiting plate is fixedly connected to the back surface of the first support plate, a third rotating rod is rotatably connected to the inner wall of the first connecting plate, a second gear is fixedly connected to the right end of the third rotating rod, a cylindrical cam is fixedly connected to the left side of the third rotating rod, a return groove connected end to end is formed on the surface of the cylindrical cam, a second connecting plate is slidably connected to the inner wall of the second limiting plate, a driven rod is fixedly connected to the front side of the second connecting plate, the surface of the driven rod is slidably connected to the groove wall of the return groove, a second toothed plate is fixedly connected to the back surface of the support frame at the left rear side, the return groove includes an inclined rising section, a horizontal maintaining section and an inclined descending section, the return groove forms a continuous closed-loop track, a wear-resistant ceramic coating is provided at the end of the driven rod, and the driven rod and the return groove are in clearance fit.

[0010] As a preferred embodiment of the present invention, an aluminum row support plate is fixedly connected to the back surface of the first support plate, a cleaning plate is fixedly connected to the left side of the second connecting plate, the bottom of the cleaning plate is in contact with the top of the aluminum row support plate, the second toothed plate meshes with the second gear, an elastic scraping blade is embedded at the bottom of the cleaning plate, and the elastic scraping blade is in elastic contact with the top of the aluminum row support plate.

[0011] As a preferred embodiment of the present invention, a support frame is fixedly connected to the top of the workbench, a welding device is installed inside the support frame, a laser locator is provided inside the support frame, and the projection spot of the laser locator is coaxial with the processing point of the welding device.

[0012] Compared with the prior art, the beneficial effects of the present invention are: In the present invention, by adopting a workpiece self-weight trigger mechanism, the electric or pneumatic power source required by the traditional clamping device is completely eliminated, the energy consumption is reduced, and true green production is achieved. The bidirectional lead screw, in cooperation with the synchronous belt drive, ensures the repeat positioning accuracy. The cross-shaped anti-slip pattern provides a stable clamping force, reducing the welding deviation rate. The innovative cam-scraper mechanism automatically completes the cleaning of the support surface in each operation cycle, improving the cleaning efficiency. The application of special materials such as polytetrafluoroethylene anti-friction coating and wear-resistant ceramic coating extends the service life of key components and the maintenance cycle. The streamlined power system and automated design reduce the manufacturing cost of the equipment and save labor costs at the same time. This device perfectly solves the industry pain points such as positioning accuracy and welding slag pollution in power battery welding through mechanical innovation, providing reliable process equipment support for new energy battery manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is of the present invention Figure 1 partial structural schematic diagram; Figure 3 is of the present invention Figure 2 partial structural schematic diagram; Figure 4 is of the present invention Figure 3 partial structural schematic diagram; Figure 5 is of the present invention Figure 4 structural plan view of the grinding component; Figure 6 is of the present invention Figure 4 structural sectional view of the mating components;

[0014] In the figure: 1, workbench; 2, support frame; 3, welder; 4, support frame; 5, fixing component; 6, second toothed plate; 501, second support plate; 502, bidirectional lead screw; 503, first rotating rod; 504, synchronous pulley; 505, synchronous belt; 506, third support plate; 507, second rotating rod; 508, first gear; 509, first toothed plate; 510, first support plate; 511, slider; 512, moving plate; 513, fixing plate; 514, first limiting plate; 515, spring; 516, mating plate; 517, aluminum row support plate; 518, cleaning plate; 519, second limiting plate; 520, second connecting plate; 521, driven rod; 522, cylindrical cam; 523, return groove; 524, third rotating rod; 525, first connecting plate; 526, second gear; 527, chute. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0016] Please refer to Figures 1-6 , the technical solutions provided by the present invention specifically include the following embodiments: Embodiment: A device for laser welding aluminum bars of battery cores to prevent welding deviation includes a workbench 1. On the front and back sides of the left and right sides of the top of the workbench 1, support frames 4 are fixedly connected. A fixing component 5 is arranged inside the support frame 4; The fixing component 5 includes a first support plate 510. On the front and back sides of the left and right sides of the first support plate 510, sliders 511 are fixedly connected. The frame wall of the support frame 4 is slidably connected to the surface of the slider 511. On the left and right sides of the bottom of the workbench 1, second support plates 501 are fixedly connected. A friction-reducing coating is provided on the contact surface between the slider 511 and the support frame 4, and the friction-reducing coating is made of polytetrafluoroethylene material; A bidirectional lead screw 502 is rotatably connected to the inner wall of the second support plate 501. On the left and right sides of the surface of the bidirectional lead screw 502, fitting plates 516 are threadedly sleeved. A moving plate 512 is slidably connected to the surface of the fitting plate 516. A chute 527 is opened at the bottom of the moving plate 512, and the groove wall of the chute 527 is slidably connected to the surface of the fitting plate 516. A spring 515 is fixedly connected to the top of the fitting plate 516, and the top of the spring 515 is fixedly connected to the top inside the moving plate 512. A first limiting plate 514 is fixedly connected to the outside of the moving plate 512. On the left side of the bottom of the workbench 1, a third support plate 506 is fixedly connected; The number of moving plates 512 is two, and the two moving plates 512 are symmetrically distributed left and right. An inner plate 513 is fixedly connected to the inner side of the moving plate 512. An anti-slip pattern is provided on the clamping surface of the inner plate 513, and the anti-slip pattern is a cross-shaped network structure; A first toothed plate 509 is fixedly connected to the left side of the first support plate 510. A first rotating rod 503 is fixedly connected to the left end of the bidirectional lead screw 502. A second rotating rod 507 is rotatably connected to the inner wall of the third support plate 506. Synchronous wheels 504 are fixedly connected to the left ends of the second rotating rod 507 and the first rotating rod 503. A synchronous belt 505 is sleeved on the surface of the synchronous wheel 504, and the synchronous belt 505 is a polyurethane synchronous belt. A wear-resistant rubber layer is provided on the tooth surface of the synchronous belt 505; A first gear 508 is fixedly connected to the right end of the second rotating rod 507, and the first gear 508 meshes with the first toothed plate 509; When the battery cell aluminum bar is placed on the aluminum bar support plate 517, the weight of the workpiece will cause the entire first support plate 510 to slide downward along the support frame 4. This downward movement is transmitted to the first gear 508 through the first toothed plate 509 fixedly connected on the left side, thereby driving the second rotating rod 507 to rotate. Since the second rotating rod 507 is connected to the first rotating rod 503 through a high-precision polyurethane timing belt 505, this transmission method ensures the synchronism and stability of power transmission, effectively avoiding the clearance error that may occur in traditional gear transmission. The rotational movement of the bidirectional lead screw 502 is accurately converted into the linear displacement of the mating plate 516. It is particularly noteworthy that the moving plate 512 forms a sliding fit with the mating plate 516 through the chute 527. This structural design not only ensures the linearity of the movement but also allows for necessary flexible buffering through the spring 515 during the clamping process. The pre-tightening force of the spring is precisely calculated to avoid damaging the surface of the aluminum bar while ensuring sufficient clamping force. The cross-shaped mesh anti-slip pattern set on the surface of the fixed plate 513 further enhances the clamping stability. The depth and spacing of its pattern are optimized to provide sufficient friction without leaving indentations on the surface of the aluminum bar. The design concept of completely relying on the self-weight of the workpiece to drive significantly reduces energy consumption, meeting the green environmental protection requirements of modern manufacturing. The entire clamping process does not require the participation of additional sensors or control systems, and the self-adaptability of the mechanical structure significantly improves the reliability of the system. The design of the bidirectional lead screw combined with the timing belt drive ensures the absolute balance of the clamping forces on both the left and right sides, which is crucial for ensuring the laser welding accuracy. The application of the polytetrafluoroethylene anti-friction coating not only reduces the wear of the sliding parts but also makes the operation of the entire mechanism smoother and quieter.

[0017] The back surface of the first support plate 510 is fixedly connected with a first connecting plate 525. The back surface of the first support plate 510 is fixedly connected with a second limiting plate 519. The inner wall of the first connecting plate 525 is rotatably connected with a third rotating rod 524. The right end of the third rotating rod 524 is fixedly connected with a second gear 526. The left side of the third rotating rod 524 is fixedly connected with a cylindrical cam 522. The surface of the cylindrical cam 522 is provided with a return groove 523 that is connected end to end. The inner wall of the second limiting plate 519 is slidably connected with a second connecting plate 520. The front side of the second connecting plate 520 is fixedly connected with a driven rod 521. The wall of the return groove 523 is slidably connected with the surface of the driven rod 521. The back surface of the support frame 4 at the left rear is fixedly connected with a second toothed plate 6. The return groove 523 includes an inclined rising section, a horizontal maintaining section, and an inclined descending section. The return groove 523 forms a continuous closed-loop track. The end of the driven rod 521 is provided with a wear-resistant ceramic coating. The driven rod 521 has a clearance fit with the return groove 523. The back surface of the first support plate 510 is fixedly connected with an aluminum row support plate 517. The left side of the second connecting plate 520 is fixedly connected with a cleaning plate 518. The bottom of the cleaning plate 518 is in contact with the top of the aluminum row support plate 517. The second toothed plate 6 is meshed with the second gear 526. The bottom of the cleaning plate 518 is embedded with an elastic scraping blade. The elastic scraping blade is in elastic contact with the top of the aluminum row support plate 517. After the welding is completed and the workpiece is taken away, the first support plate 510 starts to rise under the action of the spring. This upward movement is converted into the action of the cleaning mechanism through a precise gear and rack transmission system: the upward movement of the first toothed plate 509 drives the first gear 508 to reverse, and then drives the bidirectional lead screw 502 to reverse through the synchronous belt 505, so that the clamping mechanism is reset. At the same time, the meshing of the second toothed plate 6 and the second gear 526 converts the vertical movement into the rotational movement of the third rotating rod 524. The design of the cylindrical cam 522 is the key to this cleaning mechanism. The return groove 523 machined on its surface adopts a unique three-stage design of rising-horizontal-descending: the inclined rising section realizes the rapid approach of the cleaning plate, the horizontal maintaining section ensures sufficient cleaning time, and the inclined descending section completes the smooth reset. This movement trajectory has been optimized through fluid dynamics simulation, and can obtain the best cleaning effect with the minimum energy consumption. The high-performance wear-resistant ceramic coating used at the end of the driven rod 521 ensures the movement accuracy under long-term use. The elastic scraping blade at the bottom of the cleaning plate 518 adopts a special polyurethane composite material, which not only ensures sufficient elasticity to fit the surface of the support plate, but also has excellent high-temperature resistance. Compared with the traditional jet cleaning or manual cleaning methods, this mechanical cleaning solution has significant advantages such as low noise, low energy consumption, and simple maintenance. More importantly, it realizes the perfect synchronization with the production rhythm and does not increase the production cycle additionally.

[0018] A support frame 2 is fixedly connected to the top of the workbench 1, and a welder 3 is installed inside the support frame 2. A laser locator is provided inside the support frame 2, and the projection spot of the laser locator is coaxial with the processing point of the welder 3; The laser locator integrated inside the support frame 2 adopts a coaxial optical path design. Its positioning spot and the focal position of the welding laser are strictly calibrated to ensure that the spatial coincidence error is less than 0.05 mm. The positioning system is also equipped with an automatic compensation function, which can perform fine adjustment according to the actual position of the aluminum busbar, effectively compensating for the influence brought by mechanical tolerances. The actual application data shows that the repeated positioning accuracy of this system reaches ±0.02 mm, fully meeting the process requirements for power battery welding.

[0019] In the present invention, through the coaxial optical path design of the laser locator integrated inside the support frame 2 and the welder 3, and with the cooperation of the automatic compensation function, a repeated positioning accuracy of ±0.02 mm is achieved. The transmission system composed of the synchronous pulley 504 and the synchronous belt 505 ensures the synchronism and stability of power transmission; The weight of the workpiece will cause the entire first support plate 510 to slide downward along the support frame 4. This downward movement is transmitted to the first gear 508 through the first toothed plate 509 fixedly connected on the left side, thereby driving the second rotating rod 507 to rotate. Since the second rotating rod 507 is connected to the first rotating rod 503 through a high-precision polyurethane synchronous belt 505, this transmission method ensures the synchronism and smoothness of power transmission, effectively avoiding the clearance error that may occur in traditional gear transmission. The rotational movement of the bidirectional lead screw 502 is accurately converted into the linear displacement of the mating plate 516. It is particularly noteworthy that the moving plate 512 forms a sliding fit with the mating plate 516 through the sliding groove 527. This structural design not only ensures the linearity of movement but also allows for necessary flexible buffering through the spring 515 during the clamping process. The pre-tightening force of the spring is precisely calculated to avoid damaging the surface of the aluminum row while ensuring sufficient clamping force. The cross-shaped mesh anti-slip pattern set on the surface of the fixed plate 513 further enhances the clamping stability. The depth and spacing of its pattern are optimized to provide sufficient friction without leaving indentations on the surface of the aluminum row. The design concept of completely relying on the self-weight of the workpiece to drive significantly reduces energy consumption, meeting the green environmental protection requirements of modern manufacturing. The entire clamping process does not require the participation of additional sensors or control systems, and the self-adaptability of the mechanical structure significantly improves the reliability of the system. The design of the bidirectional lead screw combined with the synchronous belt drive ensures the absolute balance of the clamping forces on both the left and right sides, which is crucial for ensuring the laser welding accuracy. The application of the polytetrafluoroethylene anti-friction coating not only reduces the wear of the sliding parts but also makes the operation of the entire mechanism more stable and quiet. After the welding is completed and the workpiece is removed, the first support plate 510 begins to rise under the action of the spring. This upward movement is converted into the action of the cleaning mechanism through a precise gear and rack transmission system: the upward movement of the first toothed plate 509 drives the first gear 508 to reverse, and then drives the bidirectional lead screw 502 to reverse through the synchronous belt 505, resetting the clamping mechanism;Meanwhile, the engagement between the second toothed plate 6 and the second gear 526 converts the vertical motion into the rotational motion of the third rotating rod 524. The design of the cylindrical cam 522 is the key to this cleaning mechanism. The return groove 523 machined on its surface adopts a unique three-stage design of rising-horizontal-falling: the inclined rising section enables the rapid approach of the cleaning plate, the horizontal maintaining section ensures sufficient cleaning time, and the inclined falling section completes the smooth reset. This motion trajectory has been optimized through fluid dynamics simulation, enabling the best cleaning effect with the minimum energy consumption. The high-performance wear-resistant ceramic coating applied to the end of the follower rod 521 ensures the motion accuracy during long-term use. The elastic scraper at the bottom of the cleaning plate 518 is made of a special polyurethane composite material, which not only ensures sufficient elasticity to fit the surface of the support plate but also has excellent high-temperature resistance. Compared with traditional jet cleaning or manual cleaning methods, this mechanical cleaning solution has significant advantages such as low noise, low energy consumption, and simple maintenance. More importantly, it achieves perfect synchronization with the production rhythm without adding an extra production cycle.

[0020] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A device for laser welding aluminum bars of battery cells to prevent welding deviation, characterized in that: It includes a workbench (1), and support frames (4) are fixedly connected to the front and rear sides of the left and right sides of the top of the workbench (1). A fixing component (5) is arranged inside the support frame (4). The fixing component (5) includes a first support plate (510). Sliders (511) are fixedly connected to the front and rear sides of the left and right sides of the first support plate (510). The frame wall of the support frame (4) is slidably connected to the surface of the slider (511). Second support plates (501) are fixedly connected to the left and right sides of the bottom of the workbench (1). A friction-reducing coating is provided on the contact surface between the slider (511) and the support frame (4), and the friction-reducing coating is made of polytetrafluoroethylene material.

2. The device for laser welding aluminum busbars of a battery cell to prevent solder deviation according to claim 1, characterized in that: A bidirectional lead screw (502) is rotatably connected to the inner wall of the second support plate (501). Matching plates (516) are threadedly sleeved on the left and right sides of the surface of the bidirectional lead screw (502). A moving plate (512) is slidably connected to the surface of the matching plate (516). A chute (527) is formed in the bottom of the moving plate (512), and the wall of the chute (527) is slidably connected to the surface of the matching plate (516). A spring (515) is fixedly connected to the top of the matching plate (516), and the top of the spring (515) is fixedly connected to the top inside the moving plate (512). A first limiting plate (514) is fixedly connected to the outside of the moving plate (512), and a third support plate (506) is fixedly connected to the left side of the bottom of the workbench (1).

3. The device for laser welding aluminum busbars of battery cores to prevent solder deviation according to claim 2, wherein: There are two moving plates (512), and the two moving plates (512) are symmetrically distributed left and right. A fixing plate (513) is fixedly connected to the inner side of the moving plate (512). Anti-slip lines are provided on the clamping surface of the fixing plate (513), and the anti-slip lines are in a cross-net structure.

4. The device for laser welding aluminum bars of a battery core for preventing solder deviation according to claim 2, wherein: A first toothed plate (509) is fixedly connected to the left side of the first support plate (510). A first rotating rod (503) is fixedly connected to the left end of the bidirectional lead screw (502). A second rotating rod (507) is rotatably connected to the inner wall of the third support plate (506). Synchronous wheels (504) are fixedly connected to the left ends of the second rotating rod (507) and the first rotating rod (503). A synchronous belt (505) is sleeved on the surface of the synchronous wheel (504). The synchronous belt (505) is a polyurethane synchronous belt, and a wear-resistant rubber layer is provided on the tooth surface of the synchronous belt (505).

5. The device for laser welding aluminum bars of a battery cell to prevent solder deviation according to claim 4, characterized in that: A first gear (508) is fixedly connected to the right end of the second rotating rod (507), and the first gear (508) meshes with the first toothed plate (509).

6. The device for laser welding aluminum busbars of battery cores to prevent solder deviation according to claim 1, characterized in that: A first connecting plate (525) is fixedly connected to the back surface of the first support plate (510), and a second limiting plate (519) is fixedly connected to the back surface of the first support plate (510). A third rotating rod (524) is rotatably connected to the inner wall of the first connecting plate (525). A second gear (526) is fixedly connected to the right end of the third rotating rod (524). A cylindrical cam (522) is fixedly connected to the left side of the third rotating rod (524). A folded-back groove (523) that is connected end to end is formed on the surface of the cylindrical cam (522). A second connecting plate (520) is slidably connected to the inner wall of the second limiting plate (519). A driven rod (521) is fixedly connected to the front side of the second connecting plate (520). The surface of the driven rod (521) is slidably connected to the groove wall of the folded-back groove (523). A second toothed plate (6) is fixedly connected to the back surface of the support frame (4) at the left rear side. The folded-back groove (523) includes an inclined rising section, a horizontal maintaining section, and an inclined descending section. The folded-back groove (523) forms a continuous closed-loop track. A wear-resistant ceramic coating is provided at the end of the driven rod (521). The driven rod (521) has a clearance fit with the folded-back groove (523).

7. The device for laser welding aluminum bars of a battery core to prevent solder deviation according to claim 6, wherein: An aluminum row support plate (517) is fixedly connected to the back surface of the first support plate (510). A cleaning plate (518) is fixedly connected to the left side of the second connecting plate (520). The bottom of the cleaning plate (518) is in contact with the top of the aluminum row support plate (517). The second toothed plate (6) is meshed with the second gear (526). An elastic scraping blade is embedded at the bottom of the cleaning plate (518). The elastic scraping blade is in elastic contact with the top of the aluminum row support plate (517).

8. The device for laser welding aluminum busbars of a battery core to prevent solder deviation according to claim 1, wherein: A support frame (2) is fixedly connected to the top of the workbench (1). A welding device (3) is installed inside the support frame (2). A laser locator is provided inside the support frame (2). The projection light spot of the laser locator is coaxial with the processing point of the welding device (3).

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